JP2023084509A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that, even when processing is interrupted during adjustment of an image forming condition, constantly maintains the optimal correction value for the adjustment.SOLUTION: An image forming apparatus 101 comprises: a printing device 107 that forms an image on a sheet based on an image forming condition; an image reading unit 231 that reads a chart for adjustment on which images for adjustment of the image forming condition are formed on the sheet; and a CPU 222 that causes the printing device 107 to create a predetermined number of charts for adjustment necessary for adjustment, causes the image reading unit 231 to read the predetermined number of charts for adjustment, and performs adjustment processing of adjusting the image forming condition based on a result of reading of the predetermined number of charts for adjustment performed by the image reading unit 231. When the cause of interruption occurs during the adjustment processing, the CPU 222 interrupts the adjustment processing, and after the cause of interruption is solved, resumes the interrupted adjustment processing.SELECTED DRAWING: Figure 2

Description

The present invention relates to image forming apparatuses such as printers, copiers, facsimiles, and multi-function machines.

Outputs produced by commercial printers require stable print position accuracy on the front and back surfaces of sheets. Therefore, in the image forming apparatus, automatic adjustment (hereinafter referred to as "front/back auto adjustment") is performed to automatically stabilize the print position accuracy on the front and back surfaces of the sheet. By the front/back auto adjustment, for example, a correction value for the front/back printing position (image forming position) is set for each paper feeding deck. At the time of printing, the image writing position is adjusted according to the correction value set for the paper feeding deck that fed the sheet. The start position of the image is adjusted by, for example, offsetting by an amount corresponding to the correction value. The printing position is adjusted by adjusting the writing position.

Japanese Unexamined Patent Application Publication No. 2002-200001 discloses an image forming apparatus that stabilizes printing position accuracy. This image forming apparatus creates an adjustment chart by printing an adjustment image serving as a print position mark on a sheet in order to stabilize print position accuracy. The image for adjustment is read from the adjustment chart by an image reading sensor provided in the sheet conveying path. The image forming apparatus feeds back the reading result of the adjustment image to the image forming conditions, and adjusts the geometric characteristics of the image such as the printing position and the inclination of the image.

Japanese Patent Application Laid-Open No. 2006-11285

The optimum correction value for the geometric characteristics of the images on the front and back surfaces of the sheet varies depending on the environmental conditions such as the temperature in the image forming apparatus during printing (machine temperature) and the sheet conditions such as moisture absorption of the sheet. For this reason, it is preferable that the front/back automatic adjustment be performed using a plurality of adjustment charts at an appropriate timing. In the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200011, the user sets the number of sheets in the adjustment interval at which the front/back auto adjustment is performed. The image forming apparatus prints and reads a predetermined number of adjustment charts each time the set number of sheets is printed. The image forming apparatus feeds back the correction value acquired using the reading result of the adjustment chart to the image forming conditions of the subsequent job. In this way, the correction values for the print positions and the geometric characteristics of the complementary front and back images are adjusted.

Before the printing and reading of a predetermined number of adjustment charts are completed, front/back auto adjustment may be interrupted due to lack of sheets or toner in the image forming apparatus. In this case, an accurate correction value cannot be obtained because the front/back automatic adjustment using the predetermined number of adjustment charts has not been completed. Therefore, the printing is continued using the previous adjustment result of the front/back automatic adjustment instead of the interrupted adjustment result of the front/back automatic adjustment, and the front/back automatic adjustment is not properly performed for each number of sheets set by the user. This will interfere with proper correction of the geometric properties of the front and back images. Such an interruption of the operation during the adjustment process interferes with proper adjustment of other image forming conditions such as geometric characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image forming apparatus that always maintains optimum correction values for adjustment even when processing is interrupted during adjustment of image forming conditions. for the purpose.

An image forming apparatus of the present invention comprises: image forming means for forming an image on a sheet based on image forming conditions; reading means for reading an adjustment chart in which an image for adjusting the image forming conditions is formed on the sheet; A predetermined number of the adjustment charts required for adjustment are created by the image forming means, the predetermined number of the adjustment charts are read by the reading means, and the predetermined number of the adjustment charts read by the reading means are read. a control means for performing an adjustment process for adjusting the image forming conditions based on the reading result, wherein the control means interrupts the adjustment process when an interruption factor occurs during the adjustment process, and the adjustment process is interrupted when the interruption factor occurs. It is characterized in that the interrupted adjustment process is restarted after the problem is resolved.

According to the present invention, even when processing is interrupted during adjustment of image forming conditions, it is possible to perform printing while always maintaining optimal correction values for adjustment.

1 is a configuration diagram of an image processing system; FIG. system configuration diagram. 1 is a configuration diagram of an image forming apparatus; FIG. Explanatory drawing of CIS. (a) to (f) are explanatory diagrams of setting screens. FIG. 4 is an exemplary view of job information; Illustrative diagram of front/back auto adjustment information FIG. 4 is an exemplary diagram of an adjustment chart; FIG. 4 is an explanatory diagram of front/back automatic adjustment using an adjustment chart; FIG. 4 is an explanatory diagram of front/back automatic adjustment using an adjustment chart; 4 is a flowchart representing image forming processing. 5 is a flowchart showing front/back auto adjustment processing;

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

(Image processing system)
FIG. 1 is a configuration diagram of an image processing system including an image forming apparatus of 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 multi-function peripheral (MFP) or the like. The external controller 102 is, for example, an image processing controller, a digital front end (DFE), a print server, or the like.

The image forming apparatus 101 and the external controller 102 are communicably 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 acquires a print instruction (print job) from the client PC 103 .

The client PC 103 is installed with a printer driver having a function of converting image data into a print description language that can be processed by the external controller 102 . A user can instruct printing via a printer driver using various applications. The printer driver transmits image data to the external controller 102 based on a print job from the user. The external controller 102 receives a print job including image data from the client PC 103, performs data analysis and rasterization processing, and instructs the image forming apparatus 101 to perform printing (image formation) based on the image data.

The image forming apparatus 101 is configured by connecting a plurality of apparatuses having different functions, including a printing apparatus 107, and is capable of performing complicated print processing 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 using a developer (for example, toner) on a sheet fed from a paper feeding unit provided at the bottom of the main body. The printing device 107 forms yellow (Y), magenta (M), cyan (C), and black (K) images. A full-color image is formed on the sheet by superimposing images of respective colors. A sheet on which an image is formed is conveyed from the printing device 107 to the finisher 109 . A finisher 109 stacks sheets on which images are formed.

This image processing system has a configuration in which 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 acquire a print job including image data directly from the client PC 103 via the external LAN 104 . In this case, the image forming apparatus 101 performs the data analysis and rasterization processing performed by the external controller 102 . That is, the image forming apparatus 101 and the external controller 102 may be integrated.

(System configuration)
FIG. 2 is a system configuration diagram for controlling the operation of the image processing system. Controllers that control the operations of the image forming apparatus 101, the external controller 102, and the client PC 103 will be described here.

-Printing Device The printing device 107 includes a communication interface (I/F) 217, a LAN I/F 218, and a video I/F 220 in order to communicate with other devices. The printing apparatus 107 includes a CPU (Central Processing Unit) 222 , a memory 223 , a storage 221 , an image reading section 231 and an image processing section 232 to control operations of the printing apparatus 107 . The printing device 107 includes an exposure unit 227, an image forming unit 228, a fixing unit 229, and a paper feeding unit 230 for forming an image. The printing device 107 includes an operation unit 224 and a display 225 as user interfaces. The printing apparatus 107 includes a timer 251 and a temperature sensor 252 for adjusting correction values for optimally correcting the geometric characteristics of the front and back images. Here, the geometric characteristics of the image are, for example, the perpendicularity, the print position of the image on the sheet, and the like. These components are communicatively connected to each other via a system bus 233 .

A 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 apparatus 107 and the finisher 109 operate cooperatively, information and data are transmitted and received via the communication I/F 217 . LAN I/F 218 is connected to external controller 102 via internal LAN 105 and controls communication with external controller 102 . The printing device 107 receives print settings from the external controller 102 via the LAN I/F 218 . Video I/F 220 is connected to external controller 102 via video cable 106 and controls communication with external controller 102 . The printing device 107 receives image data representing an image to be formed from the external controller 102 via the video I/F 220 .

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 when the CPU 222 executes various processes. When performing image forming processing, the CPU 222 controls the exposure unit 227 , the image forming unit 228 , the fixing unit 229 and the paper feeding unit 230 .

The exposure unit 227 includes a photoreceptor, a charging wire for charging the photoreceptor, and a light source for exposing the photoreceptor charged by the charging wire to form an electrostatic latent image on the photoreceptor. The photosensitive member is, for example, a photosensitive belt having a photosensitive layer formed on the surface of a belt-like elastic member, or a photosensitive drum having a photosensitive layer formed on the surface of a cylinder. Also, a charging roller may be used instead of the charging wire. The exposure unit 227 charges the surface of the photoreceptor to a uniform negative potential with a charging wire. The exposure unit 227 outputs laser light based on image data from the light source. A laser beam scans the surface of a uniformly charged photoreceptor. As a result, the potential of the photoreceptor at the position irradiated with the laser light is changed, and an electrostatic latent image is formed on the surface of the photoreceptor. Four photoreceptors are provided corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). Electrostatic latent images corresponding to images of different colors are formed on the four photoreceptors.

The image forming unit 228 transfers the toner image formed on the photoreceptor onto a sheet. The image forming section 228 includes a developing device, a transfer unit, and a toner supply section. The developing device deposits negatively charged toner from a developing cylinder onto the electrostatic latent image formed on the surface of the photoreceptor to form a toner image. Four developing devices are provided corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). The developer visualizes the electrostatic latent image on the photoreceptor with toner of the corresponding color.

The transfer unit has an intermediate transfer belt, and transfers the toner image from the photoreceptor to the intermediate transfer belt. A primary transfer roller is provided at a position facing the photosensitive member with the intermediate transfer belt interposed therebetween. By applying a positive potential to the primary transfer roller, toner images are superimposed and transferred onto the intermediate transfer belt from each of the four photoreceptors. Thereby, a full-color toner image is formed on the intermediate transfer belt. A toner image formed on the intermediate transfer belt is transferred onto a sheet by a secondary transfer roller, which will be described later. The secondary transfer roller transfers a full-color toner image from the intermediate transfer belt to the sheet by being applied with a positive potential.

A fixing unit 229 fixes the transferred toner image on the sheet. The fixing section 229 has a heater and a roller pair. The fixing unit 229 heats and presses the toner image on the sheet with a heater and roller pair to melt and fix the toner image on the sheet. As a result, a product in which an image is formed on a sheet is generated. The paper feeding unit 230 includes a conveying roller and various sensors on a conveying path, and controls the sheet feeding operation.

The image reading unit 231 reads an image formed on the conveyed sheet based on an instruction from the CPU 222 . For example, when adjusting the image forming conditions, the CPU 222 uses the image reading unit 231 to read an image for adjusting the image forming conditions formed on the sheet. The operation unit 224 is an input device that receives various setting inputs and operation instructions from the user. The operation unit 224 is, for example, various input keys and a touch panel. A display 225 is an output device that displays setting information of the image forming apparatus 101 and the processing status (status information) of a print job.

Timer 251 counts time. The CPU 222 acquires the current date and time from the count value of the timer 251 . A temperature sensor 252 measures the internal temperature of the printing apparatus 107 . The CPU 222 acquires the internal temperature, which is one of the environmental conditions, from the measurement result of the temperature sensor 252 . Humidity may be acquired as an environmental condition in addition to temperature.

Finisher The finisher 109 staples a product output from the printing device 107, for example. The finisher 109 has a communication I/F 241 , a CPU 242 , a memory 243 , and a paper ejection control section 244 . These components are communicatively connected to each other via system bus 245 . A 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 apparatus 107 operate cooperatively, 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 necessary for paper ejection. The memory 243 stores control programs. Also, the memory 243 provides a work area when the CPU 242 executes various processes. A paper ejection control unit 244 ejects the conveyed sheet based on an instruction from the CPU 242 .

- External Controller The external controller 102 is provided with a LAN I/F 213, a LAN I/F 214, and a video I/F 215 in order to communicate with other devices. The external controller 102 comprises a CPU 208 , memory 209 and storage 210 to control the operation of the external controller 102 . The external controller 102 has a keyboard 211 and a display 212 as user interfaces. These components are communicatively connected to each other via system bus 216 .

A 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 a print job from the client PC 103 via the LAN I/F 213 . A LAN I/F 214 is connected to the printer 107 via the internal LAN 105 and controls communication with the printer 107 . The external controller 102 transmits print settings to the printer 107 via the LAN I/F 214 . A 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 to the printing device 107 via the video I/F 215 .

By executing a computer program stored in the storage 210 , the CPU 208 comprehensively performs processing such as reception of image data transmitted from the client PC 103 , RIP processing, and transmission of image data to the image forming apparatus 101 . A memory 209 provides a work area when the CPU 208 executes various processes. The keyboard 211 is an input device that receives input of various settings and operation instructions from the user. The display 212 is an output device that displays information on the application executed by the external controller 102 in the form of still images or moving images.

・Client PC
The client PC 103 has a CPU 201 , memory 202 , storage 203 , keyboard 204 , display 205 and LAN I/F 206 . These components are communicatively connected to each other via a system bus 207 .

The CPU 201 controls operations of the client PC 103 by executing computer programs stored in the storage 203 . In this embodiment, the CPU 201 performs image data creation and print job transmission processing. The memory 202 provides a work area when the CPU 201 executes various processes. Keyboard 204 and display 205 are user interfaces. The keyboard 204 is an input device that receives instructions from the user. A display 205 is an output device that displays information about an application executed by the client PC 103 in the form of still images or moving images. LAN I/F 206 is connected to external controller 102 via external LAN 104 and controls communication with external controller 102 . The client PC 103 transmits a print job including image data to the external controller 102 via the LAN I/F 206 .

The external controller 102 and the image forming apparatus 101 are connected by the internal LAN 105 and the video cable 106, but any configuration is sufficient as long as the data required for printing can be transmitted and received. may have been The memory 202, the memory 209, the memory 223, and the memory 243 may each be a storage device for holding data and programs. For these memories, for example, volatile RAM (Random Access Memory), nonvolatile ROM (Read Only Memory), storage, USB (Universal Serial Bus) memory, and the like can be used.

(Configuration of image forming apparatus)
FIG. 3 is a configuration diagram of the image forming apparatus 101. As shown in FIG. A display 225 is provided on the top of the printing device 107 . A display 225 displays the printing status of the image forming apparatus 101 and information for setting. A sheet (result) on which an image has been formed by the printing device 107 is conveyed to a finisher 109 provided at a subsequent stage.

The printing apparatus 107 includes a plurality of paper feed decks 301 and 302 and a transport path 303 as a paper feed unit 230 . Each sheet feeding deck 301, 302 can accommodate different types of sheets. Sheets accommodated in each of the sheet feeding decks 301 and 302 are separated and fed to the conveying path 303 . The printing apparatus 107 includes image forming units 304 , 305 , 306 , and 307 for forming images as an exposure unit 227 . The printing device 107 forms color images. Therefore, 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).

The printing device 107 includes an intermediate transfer belt 308 and a secondary transfer roller 309 to which toner images are transferred from the image forming units 304 , 305 , 306 , and 307 as the image forming unit 228 . The intermediate transfer belt 308 rotates clockwise in FIG. Thereby, 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. The 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 . A secondary transfer roller 309 transfers the toner image on the intermediate transfer belt 308 to the conveyed sheet.

The printing apparatus 107 includes a first fixing device 311 and a second fixing device 313 as the fixing unit 229 . The first fixing device 311 and the second fixing device 313 have the same configuration, and fix the toner image on the sheet. Therefore, the first fixing device 311 and the second fixing device 313 are provided with a pressure roller and a heating roller, respectively. The sheet is heated and pressed by passing between the pressure roller and the heating roller, and the toner image is fused and pressed. A sheet that has passed through the second fixing device 313 is conveyed to a conveying path 314 . The second fixing device 313 is arranged downstream of the first fixing device 311 in the sheet conveying direction, and is used to add gloss to the image on the sheet fixed by the first fixing device 311 and improve fixability. Used for securing. Therefore, the second fixing device 313 may not be used depending on the type of sheet and the contents of image forming processing. A conveying path 312 is provided to convey the sheet fixed by the first fixing device 311 without passing through the second fixing device 313 .

After the transport path 314 and the transport path 312 merge, a transport path 315 and a reverse path 316 are provided. When double-sided printing is instructed, the sheet is conveyed to the reversing path 316 . The sheet conveyed to the reversing path 316 is reversed in the conveying direction by the reversing path 316 and conveyed to the double-sided conveying path 317 . The image-formed surface (first surface) of the sheet is reversed by the reversing path 316 and the double-sided conveying path 317 . The sheet is conveyed to the conveying path 303 by the double-sided conveying path 317, passes through the secondary transfer roller 309 and the fixing unit 229, and an image is formed on the second side different from the first side.

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 the conveying path 315 . A transport path 323 is arranged downstream of the transport path 315 in the sheet transport direction. CISs (Contact Image Sensors) 321 and 322 as an image reading unit 231 are arranged on the transport path 323 so as to face each other with the transport path 323 interposed therebetween. FIG. 4 is an explanatory diagram of the CISs 321 and 322. As shown in FIG. The CIS 321 is an optical sensor that reads an image of the upper surface of the sheet conveyed on the conveying path 323 . The CIS 322 is an optical sensor that reads the image of the bottom surface of the sheet conveyed on the conveying path 323 .

The CIS 321 includes an LED (Light Emitting Diode) 350 as a light source, a reading sensor 351 as a light receiving portion, and a white reference plate 352 . The LED 350 irradiates the upper surface of the sheet with light at the timing when the sheet conveyed on the conveying path 323 reaches the reading position. The reading sensor 351 includes a plurality of light receiving elements (photoelectric conversion elements) in a direction perpendicular to the sheet conveying direction. Therefore, the direction orthogonal to the sheet conveying direction is the main scanning direction of the CIS 321 . The reading sensor 351 receives light reflected by the sheet. A plurality of light receiving elements of the reading sensor 351 output an output value (electrical signal) based on the intensity of the received reflected light. Output values (electrical signals) output from the plurality of light receiving elements are transmitted to the CPU 222 . The image formed on the sheet in this manner is read.

A white reference plate 352 is a calibration member (reference member) used for shading correction of the CIS 321 . During shading correction, the LED 350 and reading sensor 351 move to positions where the white reference plate 352 can be read. Alternatively, the white reference plate 352 moves to the reading position of the LED 350 and reading sensor 351 during shading correction. Shading correction of the CIS 321 is performed based on the reading result of the white reference plate 352 . Therefore, the CIS 321 cannot read the image formed on the sheet during shading correction.

The CIS 322 has an LED 353 , a reading sensor 354 and a white reference plate 355 like the CIS 321 . The CIS 322 operates in the same manner as the CIS 321 and reads the image formed on the bottom surface of the sheet at the timing when the sheet conveyed on the conveying path 323 reaches the reading position. In addition to the CISs 321 and 322, the image reading unit 231 can also be realized by a CCD or CMOS sensor.

The printing apparatus 107 of this embodiment can form adjustment images for adjusting image forming conditions on both sides of a sheet. A sheet on which an adjustment image is formed is called an adjustment chart. The printing device 107 prints the adjustment image on a sheet to create an adjustment chart, and the CIS 321 and CIS 322 read the adjustment image. The reading result (reading data) of the adjustment chart by the CIS 321 and CIS 322 is stored in the memory 223 . The CPU 222 refers to the memory 223, analyzes the data read by the CIS 321 and the CIS 322, feeds back to the image forming conditions, and adjusts the image forming conditions.

For example, when the temperature inside the printing apparatus 107 rises, the geometric characteristics of the image formed on the sheet fluctuate compared to when the temperature inside the printing apparatus 107 is low. The printing apparatus 107 creates a geometric characteristic adjustment chart and detects the geometric characteristic based on the reading results (read data) of the CISs 321 and 322 . The CPU 222 performs affine transformation on the image data so that the detected geometrical characteristics become ideal geometrical characteristics. By forming an image on a sheet based on the image data converted by the CPU 222, the printing apparatus 107 can control the geometric characteristics of the image formed on the sheet. As a result, the printing apparatus 107 can suppress variations in geometric characteristics of images caused by variations in the internal temperature.

The adjustment image formed on the adjustment chart may be an image for detecting image density or an image for detecting color misregistration, in addition to the image for detecting geometric characteristics. When an adjustment image for detecting image density is formed, the CPU 222 generates image forming conditions for suppressing variations in image density based on the read result (read data) of the CIS 321 (or CIS 322). The image density of the printing device 107 is adjusted to an ideal image density by the CPU 222 controlling the intensity of the light source of the exposure unit 227 based on the image forming conditions. Alternatively, the CPU 222 generates a one-dimensional gradation correction table for suppressing variations in image density based on the reading result (read data) of the CIS 321 (or CIS 322). The CPU 222 converts the image data based on the gradation correction table. The printing apparatus 107 forms an image on a sheet based on the image data converted by the CPU 222, thereby adjusting the image density of the printing apparatus 107 to an ideal image density.

Further, when an adjustment image for detecting color misregistration is formed, the CPU 222 detects color misregistration based on the reading result (read data) of the CIS 321 (or CIS 322). Based on the detected color shift, the CPU 222 corrects the color shift by controlling the position of the image formed on the photosensitive member by the exposure unit 227 .

The adjustment image may be printed as an adjustment chart on a sheet different from the user image, or may be printed on the same sheet as the user image. When printing as an adjustment chart, the CPU 222 uses the image data acquired from the client PC 103 and every time the number of printed sheets reaches a predetermined number N, a chart for adjustment is added between the user image for the Nth page and the user image for the (N+1)th page. Create image data with a chart inserted. When the adjustment image is formed on the same sheet as the user image, the adjustment image is preferably formed in the cutting area of the sheet. This is because the trimming process removes the adjustment image from the product. Here, the user image is an image included in image data transferred from the client PC 103 .

Adjustment charts are excluded so as not to contaminate the deliverables for the print job. For this purpose, the printing apparatus 107 includes a flapper 324 , an ejection path 326 , a transport sensor 327 and an ejection tray 328 . The chart for adjustment whose images (images for adjustment) are read by the CISs 321 and 322 is conveyed to a discharge path 326 by a flapper 324 . The sheet conveyed to the discharge path 326 is discharged to the discharge tray 328 .

If the sheet is not the adjustment chart, the sheet is conveyed from the conveying path 323 to the downstream conveying path 325 by the flapper 324 . The sheet conveyed to the downstream conveying path 325 is delivered to the finisher 109 . When the printer 107 receives a notification of the occurrence of a transport jam from the finisher 109, the printer 107 switches the flapper 324 to the discharge path 326 side to print all the sheets in the machine regardless of whether the chart is for adjustment. (remaining paper) is discharged to the discharge tray 328 . By discharging the residual paper to the discharge tray 328, the user's load of jam processing is reduced.

A finisher 109 can stack sheets transferred from the printing apparatus 107 . The finisher 109 includes 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 conveyed from the printing apparatus 107 are stacked on a stack tray 332 via a conveying path 331 . Conveyance sensors 333 , 334 , 335 , and 336 detect passage of sheets conveyed through the conveyance path 331 . If the leading edge or trailing edge of the sheet in the transport direction is not detected by the transport sensors 333, 334, 335, and 336 even after a predetermined time has passed since the start of sheet transport, the CPU 242 detects a transport jam (transport error) in the finisher 109. ) has occurred. In this case, the CPU 242 notifies the printing apparatus 107 that a transport jam has occurred.

(How to set both sides auto adjustment)
The image forming apparatus 101 of the present embodiment is capable of setting front/back auto adjustment for automatically adjusting correction values of image forming conditions (geometric characteristics) during printing. FIG. 5 is an explanatory diagram of a setting screen for setting front/back auto adjustment. The setting screen is displayed on the display 225 by the CPU 222 . The user can set front/back auto adjustment from the setting screen using the operation unit 224 . The user sets the front/back auto adjustment before instructing execution of printing.

FIG. 5(a) shows the initial screen. When the user selects the soft key "application mode" from the initial screen, the CPU 222 displays the application mode selection screen shown in FIG. When the user selects the soft key "adjustment" from the application mode selection screen, the CPU 222 causes the display 225 to display the front/back auto adjustment setting screen shown in FIG. 5(c). When the user selects the soft key "Set" from the front/back auto adjustment setting screen, the CPU 222 causes the display 225 to display the adjustment frequency selection screen shown in FIG. 5(d).

When the user selects the soft key "real time" from the adjustment frequency selection screen, the CPU 222 sets an operation mode for forming adjustment images on all pages. When the user selects the soft key "adjustment interval" from the adjustment frequency selection screen, the CPU 222 causes the display 225 to display the adjustment interval setting screen shown in FIG. When the user inputs the number of sheets using the ten keys on the adjustment interval setting screen and presses the soft key "OK", the front/back auto adjustment is enabled. In the example of FIG. 5(e), the number of sheets in the adjustment interval is set to 10 sheets. An adjustment chart is created for each number of sheets set in the adjustment interval. That is, the front/back auto adjustment is performed using the adjustment chart for each number of sheets set in the adjustment interval, and the image forming conditions (geometric characteristics) are adjusted. Note that when the user selects the soft key "cancel" from the front/back auto adjustment setting screen in FIG. 5(c), the front/back auto adjustment is disabled.

When front/back auto adjustment is set, the CPU 222 displays an initial screen on the display 225 . FIG. 5F shows the display 225 displaying the initial screen, which includes a print button 601 and an interrupt button 602 . When the user presses the print button 601, the CPU 222 executes printing. When the front/back auto adjustment is enabled, the CPU 222 creates an adjustment chart for each number of sheets set in the adjustment interval. When front/back auto adjustment is disabled, front/back auto adjustment is not performed.

Even in the case of an interrupt print job, which is interrupt processing, front/back auto adjustment can be set. When the user presses the interrupt button 602 during printing, an interrupt print job is set. After pressing the interrupt button 602 , the user activates front/back auto adjustment, sets the adjustment interval to a predetermined number of sheets (for example, 100 sheets), and presses the print button 601 . As a result, an adjustment chart is created every 100 sheets during printing by an interrupt print job.

(Information when executing a print job)
FIG. 6 is an exemplary diagram of job information stored in the memory 223 when a print job is executed. Job information is stored in the memory 223 by the CPU 222 in accordance with the input of a print job or an interrupt print job.

Job information is managed by a job ID. The job information includes the paper feed deck ID, the number of sheets in the adjustment interval, the front/back auto adjustment flag, the interrupt print flag, and the previous job ID. The paper feed deck ID indicates a paper feed deck that feeds sheets in the print job. The number of sheets in the adjustment interval is the number set on the adjustment interval setting screen. The front/back auto adjustment flag indicates the setting state (valid/invalid) of the front/back auto adjustment. For example, if the front/back auto adjustment is enabled, the front/back auto adjustment flag is set to "1", and if disabled, the front/back auto adjustment flag is set to "0". The interrupt print flag indicates whether or not the job is an interrupt print job. For example, if it is an interrupt print job, the interrupt print flag is set to "1", and if it is not an interrupt print job, the interrupt print flag is set to "0". The previous job ID is the job ID of the interrupted print job when the job is an interrupt print job.

Correction values for geometric characteristics that are adjusted in front/back automatic adjustment are set for each paper feed deck. The geometric characteristic correction value for each paper feed deck is stored in the memory 223 as front/back auto adjustment information, for example. FIG. 7 is an exemplary diagram of front/back auto adjustment information.

The paper feed deck ID (first paper feed deck ID 801 to n-th paper feed deck ID) identifies which paper feed deck the front/back auto adjustment information is for. The front/back auto adjustment information includes a front/back registration correction value for each paper feed deck. The front/back registration correction value is a value that adjusts (offsets) the writing position of each image on the front/back side. The CPU 222 reads the front/back auto adjustment information at the timing of starting the printing process. For example, in the case of a print job that feeds sheets from the paper feed deck 301 (first paper feed deck), the CPU 222 sets the front/back registration main scanning offset value 802 and the front/back registration sub-scanning offset value 803 of the first paper feeding deck ID 801 to Read to offset the writing position of the image. The front/back registration main scanning offset value 802 and the front/back registration sub-scanning offset value 803 are updated based on the reading result (reading data) of the adjustment image.

The CPU 222 counts the total number of printed sheets of the printing apparatus 107 . The number of sheets to be adjusted 804 holds the total accumulated number of printed sheets at the time when the front/back auto adjustment is executed. The adjustment execution time 805 holds the time acquired by the CPU 222 from the timer 251 when the front/back automatic adjustment is executed. The adjustment execution temperature 806 holds the internal temperature obtained by the CPU 222 from the temperature sensor 252 when the front/back automatic adjustment is executed.

(Adjustment image)
FIG. 8 is an exemplary diagram of an adjustment chart. When front/back auto adjustment is enabled, an adjustment chart is created by printing an adjustment image on a sheet every number of sheets set in the adjustment interval. As for the adjustment chart, the CIS 321 reads the adjustment image on the front side, and the CIS 322 reads the adjustment image on the back side. The CPU 222 calculates the displacement amount of the adjustment image from the reference position based on the reading result (read data) of the adjustment image by the CISs 321 and 322 . The CPU 222 determines correction values (front/back registration main scanning offset value and front/back registration sub-scanning offset value) for each of the main scanning direction and the sub-scanning direction based on the calculated deviation amount. In this embodiment, the correction values of the three adjustment charts are calculated, and the average value thereof is used as the correction value (front and back registration main scanning offset value and front and back registration sub-scanning offset value). good. The CPU 222 updates the automatic adjustment information in the memory 223 with the determined correction value. For example, when paper is fed from the paper feed deck 301, the CPU 222 updates the front/back registration main scanning offset value 802 and the front/back registration sub-scanning offset value 803 with the determined correction value.

Note that the adjustment image formed together with the user image is also the adjustment image shown in FIG. Adjustment images are formed at the four corners of the user image. As for the adjustment image formed together with the user image, the correction value is determined based on the reading result (read data) by the CIS 321 and 322 in the same manner as the adjustment chart.

(Both sides auto adjustment)
9 and 10 are explanatory diagrams of the front/back automatic adjustment process using the adjustment chart for the front/back automatic adjustment. 9 and 10, the operation up to recovery when print processing is interrupted due to the image forming apparatus 101 during front/back auto adjustment will be described. Interruption of print processing caused by the image forming apparatus 101 includes no sheets in the paper feed decks 301 and 302, no developer (toner), full sheets on the discharge tray 328 and stack tray 332, occurrence of jams during sheet conveyance, and the like. caused by Note that the event that causes the print processing to be interrupted is not limited to this. A case will be described below in which three sheets of adjustment charts are interrupted and printed while a plurality of sheets (a plurality of pages) are being continuously printed by a print job, and then the subsequent print job is performed. In subsequent print jobs, printing is performed under the image forming conditions adjusted by the front/back auto adjustment. Note that the number of adjustment charts to be printed may be any number as long as the correction values obtained as a result of the front/back automatic adjustment are accurately reflected in the product.

FIG. 9 illustrates a case where automatic front/back adjustment is executed during print processing of job A for which front/back automatic adjustment is enabled. Here, the print processing of job A is not interrupted. When the adjustment interval of front/back auto adjustment is set to 100 sheets on the setting screen, three adjustment charts are printed when the number of printed sheets reaches the adjustment interval number (100 sheets) from the previous adjustment. That is, before printing the 101st page of job A, three sheets of adjustment charts are printed and automatic front/back adjustment is performed. The three adjustment charts are prepared one by one and read one by one.

The correction value (front/back correction value) up to the 100th page of job A is "3". When the correction values are calculated using the three adjustment charts, the calculated correction values are applied to the printing process for pages after the restart. When the number of printed sheets reaches the adjustment interval number of sheets, the correction value is calculated using the adjustment chart before the printing of the 101st page of job A is started. Here, correction values of "4", "5", and "6" are calculated from the read results (read data) of the three adjustment charts. The finally calculated correction value is "5", which is the average value of the three correction values. This front/back correction value "5" is applied to the front/back correction value of the 101st page of job A. By using such correction values, an image is printed on the product with optimum geometric characteristics.

Note that the front/back correction value calculation method may be another method. For example, a maximum value, a minimum value, an intermediate value, or the like of a plurality of correction values obtained from a plurality of adjustment charts may be used as the front and back correction values. Further, in the present embodiment, the front/back correction values are applied from the printing of the 101st page immediately after adjustment, but another application method may be used. For example, in a machine having a long sheet conveying path and a plurality of sheets being conveyed inside the machine, it is difficult to apply the correction value adjusted from the sheet immediately after the adjustment chart. In such a case, the adjusted correction value may be applied not immediately after the adjustment sheet but from the sheet after a predetermined number of sheets (such as the 105th page).

FIG. 10 illustrates a case where the process is interrupted during the execution of the front/back automatic adjustment during the printing process of job A for which the front/back automatic adjustment is enabled. As described with reference to FIG. 9, after printing of the 100th page in job A is completed, correction values are calculated using three adjustment charts. In FIG. 10, the image forming apparatus 101 suspends the printing process after two adjustment charts are printed. Before the interrupted state is canceled and the print processing of the 101st page of job A is started, the remaining adjustment charts that were not printed due to the interruption are printed. In FIG. 10, the remaining one adjustment chart is printed. As a result, correction values are calculated using the three adjustment charts, and the 101st and subsequent pages of job A are printed using the correction values.

Here, correction values of "7", "5", and "6" are calculated from the read results (read data) of the three adjustment charts. The final calculated correction value is "6", which is the average value of the three correction values. This front/back correction value "6" is applied to the front/back correction value of the 101st page of job A. By using such a correction value, printing of the product is performed with optimum geometric characteristics.

In the present embodiment, the case in which printing is interrupted before the printing of a plurality of adjustment charts is completed has been described as an example. For example, if the process is interrupted due to a jam while printing and reading one adjustment chart, the adjustment process may be restarted from the creation of the adjustment chart.

Conventionally, when the front/back correction value of the 100th page of job A is "3", the same "3" as that of the 100th page is used as the front/back correction value of the 101st page if calculation of the correction value has not been completed. . In order to prevent this, in the present embodiment, when returning from the interruption, the processing resumes from the interrupted printing of the adjustment chart. By calculating the correction value before the start of printing of the 101st sheet of job A, it becomes possible to correct the image forming conditions at an appropriate timing.

(Image formation processing with front/back auto adjustment)
FIG. 11 is a flow chart showing the image forming process of this embodiment. This processing is started when the printing apparatus 107 receives a print job start instruction from the operation unit 224 or the client PC 103 .

Upon receiving the print job start instruction, the CPU 222 starts print processing corresponding to the print job (S1201). The CPU 222 increments the adjustment execution counter by 1 each time one page is printed (S1202). The adjustment execution counter represents the cumulative number of sheets printed with images corresponding to the job after the previous front/back auto adjustment was executed. The CPU 222 determines whether or not the adjustment execution counter has reached the adjustment interval number of sheets for executing the front/back auto adjustment (S1203).

When the adjustment execution counter reaches the adjustment interval number of sheets (S1203: Y), the CPU 222 executes front/back auto adjustment (S1204). The CPU 222 that has executed the front/back automatic adjustment clears the adjustment execution counter (S1205). After that, the CPU 222 determines whether or not there is a cause for interrupting the printing process (S1206). If the adjustment execution counter has not reached the adjustment interval number of sheets (S1203: N), the CPU 222 determines whether or not there is a cause for interrupting the printing process without performing front/back auto adjustment and clearing the adjustment execution counter (S1206). ).

If there is an interrupt factor (S1206: Y), the CPU 222 interrupts the print processing corresponding to the print job (S1207). The CPU 222 that interrupted the process waits until the cause of interruption is eliminated (S1208: N). During this time, the CPU 222 instructs the user to eliminate the interrupt factor through the display 225 . Dissolution of the cause of interruption indicates that a response has been taken according to the cause of the interruption. For example, if the cause of interruption is that there are no sheets in the sheet feeding decks 301 and 302, the cause of interruption is resolved by supplying sheets to the sheet feeding decks 301 and 302 by the user. In this case, an instruction is displayed on the display 225 to prompt the sheet supply to the sheet feeding decks 301 and 302 until the cause of interruption is resolved. If the cause of interruption is that the stack tray 332 is full of sheets, the cause of interruption is resolved by removing the sheets from the stack tray 332 by the user. In this case, an instruction prompting removal of the sheet from the stack tray 332 is displayed on the display 225 until the cause of interruption is resolved.

When determining that the cause of interruption has been resolved (S1208: Y), the CPU 222 determines whether or not print processing based on the print job has ended (S1209). If the print process has not ended (S1209: N), the CPU 222 returns to the process of S1201 and prints the next page. If the printing process has ended (S1209: Y), the CPU 222 ends the image forming process.

If there is no interruption factor (S1206: N), the CPU 222 determines whether or not the print processing based on the print job has ended without performing the processing of S1207 and S1208 regarding interruption of processing (S1209). If the print process has not ended (S1209: N), the CPU 222 returns to the process of S1201 and prints the next page. If the printing process has ended (S1209: Y), the CPU 222 ends the image forming process.

FIG. 12 is a flow chart showing the front/back automatic adjustment processing in S1204. Also in the front/back auto adjustment process, the process may be interrupted due to the same factor as in S1206.

When the front/back auto adjustment is started, the CPU 222 prints an adjustment image on a sheet to create an adjustment chart (S1301). The CPU 222 reads the adjustment image of the adjustment chart using the CIS 321 and 322 of the image reading unit 231 (S1302). The CPU 222 acquires the reading result (reading data) of the adjustment image from the image reading unit 231 and stores it in the memory 223 (S1303). The CPU 222 increments a read number counter indicating the number of read adjustment charts by one (S1304).

Next, the CPU 222 determines whether or not there is a cause for interrupting the printing process (S1305).
If there is an interrupt factor (S1305: Y), the CPU 222 interrupts the front/back auto adjustment process (S1306). The CPU 222 that interrupted the process waits until the cause of interruption is resolved (S1307: N). During this time, the CPU 222 instructs the user to eliminate the interrupt factor through the display 225 . Resolving the cause of interruption indicates that a response has been made according to the cause of interruption, and is the same as the processing in S1208.

If it is determined that the interruption factor has been resolved (S1307: Y), the CPU 222 determines whether or not the read number counter has reached a predetermined number required for adjustment (S1308). In this embodiment, the predetermined number is "3". That is, read data is generated from the three adjustment charts and stored. If the predetermined number has not been reached (S1308: N), the CPU 222 returns to the process of S1301 to create the next adjustment chart.

If there is no interruption factor (S1305: N), the CPU 222 determines whether or not the read number counter has reached a predetermined number necessary for adjustment without performing the processing of S1306 and S1307 regarding interruption of processing (S1308). ). If the predetermined number has not been reached (S1308: N), the CPU 222 returns to the process of S1301 to create the next adjustment chart.

If the read number counter has reached the predetermined number (S1308: Y), the CPU 222 generates a correction value based on the predetermined number of read data and reflects it in the image forming conditions (S1309). The CPU 222 clears the number-of-reads counter (S1310). Thus, the front/back auto adjustment processing is completed.

As described above, according to the present embodiment, even if the processing is interrupted during execution of the image forming condition adjustment processing such as front/back auto adjustment, it is possible to perform the optimum adjustment. The adjustment is performed using the number adjustment chart. Therefore, printing can be performed under optimum image forming conditions. The present embodiment is effective for image forming conditions that are adjusted using a plurality of adjustment charts, such as image forming conditions such as gradation correction, image density, and color misregistration.

In the above processing, an example has been described in which the number of read sheets is counted, and the adjustment chart creation processing and reading processing are repeated until the number of read sheets reaches the predetermined number required for adjustment. The above processing may be performed by counting the number of created adjustment charts in addition to the number of read sheets. Alternatively, the above process may be performed by counting the number of read results (read data) saved in the memory 223 . In either case, the adjustment chart creation processing and reading processing are repeatedly performed until a predetermined number (three in this embodiment) of reading results required for adjustment are acquired.

Further, in the above process, whether or not to perform front/back auto adjustment according to the number of sheets printed by the print job is determined, but this may be determined based on time. For example, when a predetermined time elapses after the previous front/back automatic adjustment is performed, image forming condition adjustment such as front/back automatic adjustment may be performed. Further, if the environmental conditions (temperature, humidity) at the time of the previous automatic front/back adjustment have changed by a predetermined amount or more, adjustment of image forming conditions such as front/back automatic adjustment may be performed. In this case, the image forming apparatus 101 is equipped with a measuring device such as a sensor for measuring environmental conditions.

Claims (10)

image forming means for forming an image on a sheet based on image forming conditions;
reading means for reading an adjustment chart in which an image for adjusting the image forming conditions is formed on the sheet;
A predetermined number of the adjustment charts required for adjustment are created by the image forming means, the predetermined number of the adjustment charts are read by the reading means, and the predetermined number of the adjustment charts read by the reading means are read. a control means for performing adjustment processing for adjusting the image forming conditions based on the reading result of
The control means interrupts the adjustment process when an interruption factor occurs during the adjustment process, and resumes the interrupted adjustment process after the interruption factor is resolved.
Image forming device. The control means is characterized in that, during the period from the occurrence of the interruption factor until the interruption factor is removed,
The image forming apparatus according to claim 1. The control means causes the image forming means to create the adjustment chart, causes the reading means to read the adjustment chart, and stores the reading result of the adjustment chart by the reading means in a predetermined storage means. , determining the presence or absence of the interruption factor after saving the reading result in the saving means,
3. The image forming apparatus according to claim 1. The control means counts the number of sheets of the adjustment chart read by the reading means, and when the counted number of sheets to be read reaches the predetermined number, the control means adjusts the image forming conditions based on the reading result of the predetermined number. characterized by adjusting
The image forming apparatus according to any one of claims 1 to 3. The control means counts the number of adjustment charts created by the image forming means, and when the counted number of created adjustment charts reaches the predetermined number, the control means adjusts the image forming conditions based on the reading result of the predetermined number. characterized by adjusting
The image forming apparatus according to any one of claims 1 to 3. The control means stores the reading result of the adjustment chart in a predetermined storage means by the reading means, counts the number of stored reading results stored in the storage means, and determines whether the counted number of stored data is When the predetermined number is reached, the image forming conditions are adjusted based on the predetermined number of reading results,
The image forming apparatus according to any one of claims 1 to 3. The control means adjusts the image forming conditions based on the average value of the predetermined number of reading results,
The image forming apparatus according to any one of claims 1 to 6. The image forming means forms an image on a sheet according to a print job,
The control means executes the adjustment process when the number of sheets on which images have been formed according to the print job since the previous adjustment of the image forming conditions reaches a predetermined adjustment interval number of sheets.
The image forming apparatus according to any one of claims 1 to 7. The control means executes the adjustment process when a predetermined time has passed since the previous adjustment process,
The image forming apparatus according to any one of claims 1 to 7. further comprising measuring means for measuring changes in environmental conditions of the image forming apparatus;
The control means executes the adjustment process when the environmental condition has changed by a predetermined amount or more from the previous adjustment process,
The image forming apparatus according to any one of claims 1 to 7.

Images