JP2023104101A - image forming device - Google Patents

Abstract

To always form an image on the sheet under an optimum image forming condition.SOLUTION: An image forming device 101 includes the steps of: determining the interruption time from the occurrence of the interruption during the formation of an adjustment image by image forming parts 304, 305, 306, 307 or during the reading of the adjustment image by an image reading part 231 to the return based on the time measurement result of a timer 251; and controlling whether or not to form the adjustment image in the image forming parts 304, 305, 306, 307 before starting a print job after return from interruption based on the interruption time.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine of these.

2. Description of the Related Art Conventionally, for a product produced by an image forming apparatus such as a commercial printing machine, stabilization of print position accuracy on the front and back surfaces of a sheet is required. Conventionally, such an image forming apparatus performs automatic adjustment (hereinafter referred to as "front/back auto adjustment") in order to automatically stabilize print position accuracy on the front and back surfaces of a sheet. By the front/back auto adjustment, for example, correction values for image forming positions on the front/back sides are set for each paper feeding deck. During image formation, the image forming apparatus adjusts the image forming position by adjusting the image writing position according to the correction value set in the sheet 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.

Japanese Patent Application Laid-Open No. 2002-200001 discloses an image forming apparatus that stabilizes printing position accuracy. The image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200002 prints an adjustment image as a mark of the print position on the sheet to create an adjustment chart for stabilizing the print position accuracy. The image for adjustment of the chart for adjustment is read by the sensor. Then, the image forming apparatus of Patent Document 1 feeds back the result of reading the adjustment image to the image forming conditions, and adjusts the geometric characteristics of the image such as the printing position or the inclination of the image.

In general, the optimum correction value for the geometric characteristics of the images on the front and back surfaces of the sheet changes depending on the environmental conditions such as the internal temperature of the image forming apparatus during printing, or the sheet conditions such as moisture absorption of the sheet. Therefore, it is preferable that the front/back automatic adjustment be performed at an appropriate timing using a plurality of adjustment charts. Therefore, in Patent Document 1, a predetermined number of adjustment charts are printed and read every time the number of sheets in the set adjustment interval is printed, and the read result is fed back to the image forming conditions of the subsequent job to determine the print position or A method of adjusting the geometric properties of the image is conceivable.

Japanese Patent Application Laid-Open No. 2006-11285

However, when the above method is adopted in Patent Document 1, printing or reading of the adjustment chart may be interrupted due to running out of paper or running out of toner before completing printing and reading of the predetermined number of adjustment charts. . In this case, since the reading data of the predetermined number of adjustment charts has not been obtained, the correction values for the front/back automatic adjustment cannot be created. Therefore, in this case, printing is continued using the adjustment result of the previous front/back automatic adjustment, and there is a problem that the front/back automatic adjustment for each number of sheets set by the user is not properly performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can always form an image on a sheet under optimum image forming conditions.

An image forming apparatus according to the present invention is an image forming apparatus that forms an image on a sheet based on image forming conditions, and includes: image forming means for forming an adjustment image on the sheet; reading means for reading the adjustment image; control means for generating the image forming conditions based on the reading result of the adjustment image read by the reading means; and timer means for measuring time; The control means controls an interruption time from an interruption during the formation of the image for adjustment by the image forming means or the reading of the image for adjustment by the reading means until recovery based on the time measurement result of the time measurement means. and whether or not the image forming unit forms the adjustment image before starting the print job after returning from the interruption is controlled based on the interruption time.

According to the present invention, it is possible to always form an image on a sheet under optimum image forming conditions.

1 is a schematic diagram of an image processing system according to an embodiment of the present invention; FIG. 1 is a block diagram showing the configuration of an image processing system according to an embodiment of the present invention; FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a schematic diagram of a CIS of an image forming apparatus according to an embodiment of the invention; FIG. FIG. 4 is a diagram showing an example of an image displayed on the display of the image forming apparatus according to the embodiment of the invention; FIG. 5 is a diagram showing an example of job information when a print job is executed by the image forming apparatus according to the embodiment of the present invention; 4 is a diagram showing an example of front/back automatic adjustment information of the image forming apparatus according to the embodiment of the present invention; FIG. FIG. 5 is a diagram showing an example of an adjustment chart formed by the image forming apparatus according to the embodiment of the invention; FIG. 3 is a schematic diagram showing front/back automatic adjustment performed by the image forming apparatus according to the embodiment of the present invention; 4 is a flowchart of image forming processing executed by the image forming apparatus according to the embodiment of the present invention; FIG. 4 is a flow diagram of front/back automatic adjustment processing executed by the image forming apparatus according to the embodiment of the present invention; FIG. FIG. 7 is a flow diagram of interruption time interval determination processing executed by the image forming apparatus according to the embodiment of the present invention;

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

<Configuration of image processing system>
A configuration of an image processing system 1 including an image forming apparatus 101 according to an embodiment of the present invention will be described in detail with reference to FIG.

The image processing system 1 has an image forming apparatus 101 , an external controller 102 , and a client personal computer (hereinafter referred to as “client PC”) 103 .

The image forming apparatus 101 is, for example, a multi-function peripheral (MFP) or the like. The image forming apparatus 101 is configured by connecting a plurality of apparatuses having different functions, including a printing apparatus 107, and performs complicated print processing such as bookbinding. Devices having multiple different functions are exemplified here by the printing device 107 and the finisher 109 .

The printing device 107 forms an image using a developer (for example, toner) on a sheet fed from a paper feeding unit (not shown in FIG. 1) provided at the bottom of the device main body. The printing device 107 superimposes yellow (Y), magenta (M), cyan (C), and black (K) images on a sheet to form a full-color image on the sheet. The printing apparatus 107 conveys the image-formed sheet to the finisher 109 .

A finisher 109 stacks sheets on which images are formed and conveyed from the printing apparatus 107 . A finisher 109 staples sheets conveyed from the printing apparatus 107, for example.

The external controller 102 is, for example, an image processing controller, a digital front end (DFE), or a print server. The external controller 102 is connected to the client PC 103 via the external LAN 104 . The external controller 102 receives a print job including image data from the client PC 103, performs data analysis and rasterization processing based on the received print job, and performs printing (image formation) based on the image data to the image forming apparatus 101. instruct.

Details of the configuration of each of the external controller 102, client PC 103, printing apparatus 107, and finisher 109 will be described later.

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 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 . When the user executes various applications, the client PC 103 transmits a print job including image data to the external controller 102 via the printer driver and instructs printing.

Note that the image processing system 1 having the above configuration has a configuration in which the external controller 102 is connected to the image forming apparatus 101, but the configuration is not limited to this, and the external controller 102 is not necessarily required. For example, the image forming apparatus 101 and the external controller 102 may be integrated, and the image forming apparatus 101 may acquire print jobs 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 .

The external controller 102 and the image forming apparatus 101 are connected by the internal LAN 105 and the video cable 106, but they may be connected only by the video cable 106, for example, as long as they can transmit and receive data necessary for printing. may

<External controller configuration>
A configuration of the external controller 102 connected to the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

The external controller 102 includes a CPU 208, a memory 209, a storage 210, a keyboard 211, a display 212, a LAN interface (hereinafter referred to as "I/F") 213, a LAN I/F 214, and a video I/F 215. and have. The CPU 208 , memory 209 , storage 210 , keyboard 211 , display 212 , LAN I/F 213 , LAN I/F 214 and video I/F 215 are communicably connected to each other via a system bus 216 .

The CPU 208 controls operations of the external controller 102 based on print jobs input from the LAN I/F 213 by executing computer programs stored in the storage 210 . Specifically, the CPU 208 performs RIP processing on image data included in a print job input from the LAN I/F 213 , outputs the RIP-processed image data to the video I/F 215 , and outputs the RIP-processed image data to the image forming apparatus 101 . It performs processing such as transmission of image data to The CPU 208 outputs to the LAN I/F 214 print settings set based on the print job input from the LAN I/F 213 .

The memory 209 functions as a work area when the CPU 208 executes various processes. The memory 209 can use, for example, a volatile RAM (Random Access Memory), a nonvolatile ROM (Read Only Memory), a storage, or a USB (Universal Serial Bus) memory. The memory 209 is not limited to the above, and may be any storage device for holding data or programs.

The storage 210 stores computer programs in advance.

The keyboard 211 is a user interface and an input device that receives inputs or operations for various settings from the user.

The display 212 is a user interface, and 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.

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 . LAN I/F 213 acquires a print job from client PC 103 and outputs the acquired print job to CPU 208 .

A LAN I/F 214 is connected to the printer 107 via the internal LAN 105 and controls communication with the printer 107 . A LAN I/F 214 transmits print settings set by the CPU 208 to the printing apparatus 107 .

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 . A video I/F 215 transmits image data input from the CPU 208 to the printing device 107 .

<Configuration of client PC>
A configuration of the client PC 103 connected to the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

The client PC has a CPU 201 , a memory 202 , a storage 203 , a keyboard 204 , a display 205 and a LAN I/F 206 . The CPU 201 , memory 202 , storage 203 , keyboard 204 , display 205 and LAN I/F 206 are connected via a system bus 207 so as to be able to communicate with each other.

The CPU 201 controls operations of the client PC 103 by executing computer programs stored in the storage 203 . Specifically, the CPU 201 creates image data based on electrical signals input from the keyboard 204 . The CPU 201 creates a print job according to the user's operation of the keyboard 204 and outputs the created print job together with the image data to the LAN I/F 206 .

The memory 202 functions as a work area when the CPU 201 executes various processes. The memory 202 can use, for example, a volatile RAM (Random Access Memory), a nonvolatile ROM (Read Only Memory), a storage, or a USB (Universal Serial Bus) memory. Note that the memory 202 is not limited to the above, and may be any storage device for holding data or programs.

The storage 203 stores computer programs in advance.

The keyboard 204 is a user interface and an input device that receives instructions from the user. The keyboard 204 outputs an electrical signal to the CPU 201 according to the user's instruction.

A display 205 is a user interface, and is an output device that displays information of 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 LAN I/F 206 transmits the print job input from the CPU 201 including the image data input from the CPU 201 .

<Configuration of printing device>
A configuration of the printing device 107 of the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIGS. 2 and 3. FIG.

The printing device 107 includes a communication I/F 217 , a LAN I/F 218 , a video I/F 220 , a storage 221 , a CPU 222 , a memory 223 , an operation section 224 and a display 225 . The printing apparatus 107 also includes an exposure unit 227, an image forming unit 228, a fixing unit 229, a paper feeding unit 230, an image reading unit 231, an image processing unit 232, a timer 251, a temperature sensor 252, It has

The printing device 107 also includes a first paper feeding deck 301 , a second paper feeding deck 302 , a primary transfer roller 310 , a first fixing device 311 and a second fixing device 313 . Further, the printing device 107 includes a contact image sensor (hereinafter referred to as “CIS”) 321 , CIS 322 , flapper 324 and discharge tray 328 .

A communication I/F 217 is connected to the finisher 109 via a communication cable 249 and controls communication with the finisher 109 . The communication I/F 217 transmits information or data to or receives information or data from the finisher 109 when the printing apparatus 107 and the finisher 109 operate cooperatively.

LAN I/F 218 is connected to external controller 102 via internal LAN 105 and controls communication with external controller 102 . LAN I/F 218 receives print settings from external controller 102 and outputs them to CPU 222 .

Video I/F 220 is connected to external controller 102 via video cable 106 and controls communication with external controller 102 . Video I/F 220 receives image data representing an image to be formed from external controller 102 and outputs the data to CPU 222 .

The storage 221 stores computer programs in advance.

A CPU 222 as a control unit comprehensively controls image processing or printing by executing a computer program stored in the storage 221 . The CPU 222 executes an image forming process, which will be described later, based on the print settings input from the LAN I/F 218 and the image data input from the video I/F 220, so that the exposure unit 227, image forming unit 228, It controls the fixing unit 229 and the paper feeding unit 230 .

The CPU 222 executes front/back automatic adjustment processing, which will be described later, to control the image reading unit 231 to read the adjustment image formed on the sheet, and based on the result of reading the adjustment image by the image reading unit 231 . Generate image forming conditions. The CPU 222 functions as generating means for generating image forming conditions based on the result of reading the adjustment image read by the image reading section 231 .

The CPU 222 acquires the current date and time from the count value input from the timer 251 . The timer 251 functions as time measuring means for measuring time. The CPU 222 acquires the internal temperature, which is one of the environmental conditions, from the measurement result input from the temperature sensor 252 . In addition, CPU222 may acquire humidity other than temperature as an environmental condition.

The memory 223 functions as a work area when the CPU 222 executes various processes. The memory 223 can use, for example, a volatile RAM (Random Access Memory), a nonvolatile ROM (Read Only Memory), a storage, or a USB (Universal Serial Bus) memory. The memory 223 is not limited to the above, and may be any storage device for holding data or programs.

The operation unit 224 is a user interface and an input device that receives input of various settings or operation instructions from the user. The operation unit 224 is, for example, various input keys or a touch panel.

A display 225 is a user interface, and is an output device that displays setting information of the image forming apparatus 101 or the processing status (status information) of a print job. A display 225 is provided on the top of the printing device 107 .

The exposure unit 227 includes an image forming unit 304 , an image forming unit 305 , an image forming unit 306 and an image forming unit 307 .

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 image forming units 304, 305, 306, and 307 each include a photoreceptor, a charging wire, and a light source (not shown).

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.

A charging wire charges the surface of the photoreceptor to a uniform negative potential to form an electrostatic latent image on the photoreceptor. A charging roller may be provided instead of the charging wire.

The light source outputs laser light based on image data input from the image processing unit 232, and scans and exposes the surface of the photosensitive member uniformly charged by the charging wire with the laser light. An electrostatic latent image is formed on the surface of the photoreceptor by varying the potential at the position irradiated with the laser beam. The photoreceptor is a photoreceptor belt in which a photoreceptor layer is formed on the surface of a belt-like elastic member, or a photoreceptor drum in which a photoreceptor layer is formed on the surface of a cylinder.

The image forming unit 228 transfers the toner image formed on the photosensitive member of the exposure unit 227 onto a sheet. The image forming section 228 includes an intermediate transfer belt 308, a secondary transfer roller 309, and a developing device, transfer unit, and toner supply section, all of which are not shown.

The intermediate transfer belt 308 rotates clockwise in FIG. Toner images are transferred onto the intermediate transfer belt 308 from the image forming unit 307 , the image forming unit 306 , the image forming unit 305 and the image forming unit 304 in this order. are superimposed and transferred. A full-color toner image is formed on the intermediate transfer belt 308 by superimposing and transferring the toner images. 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 synchronization with the timing at which the toner image is conveyed. The secondary transfer roller 309 transfers the full-color toner image on the intermediate transfer belt 308 to the conveyed sheet by applying a positive potential.

The developing device attaches negatively charged toner from the developing cylinder to 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 fixing unit 229 heats and presses the toner image on the sheet conveyed from the image forming unit 228 to melt and fix the toner image on the sheet, thereby forming an image on the sheet.

The fixing section 229 includes a first fixing device 311 and a second fixing device 313 .

The first fixing device 311 heats and presses the sheet on which the toner image has been transferred to melt and press the toner image onto the sheet, thereby performing a fixing process of fixing the toner image onto the sheet. The first fixing device 311 conveys the sheet on which the toner image is fixed to the second fixing device 313 or the conveying path 312 .

The second fixing device 313 has the same configuration as the first fixing device 311 and is arranged downstream of the first fixing device 311 in the sheet conveying direction. The second fixing device 313 applies gloss to the image on the sheet and ensures fixability of the sheet conveyed from the first fixing device 311, and performs gloss addition and fixability on the sheet. are transported to the transport path 314 . The second fixing device 313 may not be used depending on the type of sheet or the contents of the image forming process.

The sheet feeding unit 230 includes a first sheet feeding deck 301, a second sheet feeding deck 302, and a transport path 303, and controls sheet feeding operations.

The first sheet feeding deck 301 can accommodate sheets.

The second sheet feeding deck 302 can accommodate different types of sheets than the first sheet feeding deck 301 .

The uppermost sheet among the sheets accommodated in the first sheet feeding deck 301 or the second sheet feeding deck 302 is separated and fed to the conveying path 303 .

An image reading unit 231 serving as reading means reads an image formed on a conveyed sheet based on an instruction from the CPU 222 and outputs image data of the read image to the image processing unit 232 . The image reading unit 231 has a CIS 321 and a CIS 322 .

The CIS 321 is an optical sensor that is provided on the conveying path 323 and reads an image of the upper surface of the sheet conveyed on the conveying path 323 .

The CIS 322 is provided on the transport path 323 and arranged to face the CIS 321 with the transport path 323 interposed therebetween. 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 details of the configuration of the image reading unit 231 will be described later.

Image data is input from the image reading unit 231 to the image processing unit 232 . The image processing unit 232 converts the image data from the RGB color space to the YMCK color space, and performs screen processing on the image data converted to the YMCK color space. The image processing unit 232 outputs the screen-processed image data to the exposure unit 227 .

The timer 251 counts time and outputs a count value to the CPU 222 .

A temperature sensor 252 measures the internal temperature of the printing apparatus 107 and outputs the measurement result to the CPU 222 .

A primary transfer roller 310 is provided at a position facing the photosensitive member with the intermediate transfer belt 308 interposed therebetween. The primary transfer roller 310 is applied with a positive potential to superimpose and transfer the toner images from the four photoreceptors onto the intermediate transfer belt 308 .

The flapper 324 switches between sheet transport from the transport path 323 to the downstream transport path 325 and transport from the transport path 323 to the discharge path 326 .

The sheet conveyed to the discharge path 326 is discharged to the discharge tray 328 .

The printing apparatus 107 is provided with a transport path 315 and a reversing path 316 on the downstream side of the sheet transport direction where the transport paths 314 and 312 merge. A transport path 323 is arranged downstream of the transport path 315 in the sheet transport direction.

In the printing apparatus 107 having the above configuration, the sheet is conveyed to the conveying path 315 in the case of single-sided printing or in the case of double-sided printing in which images are formed on both sides.

When double-sided printing is instructed, the sheet is conveyed to a reversing path 316 where the conveying direction is reversed and conveyed to a double-sided conveying path 317 . As a result, the surface (first surface) on which the image is formed on the sheet is reversed. Then, the sheet is conveyed to the conveying path 303 via the double-sided conveying path 317 and passes through the secondary transfer roller 309 and the fixing section 229 . As a result, an image is formed on the second side of the sheet, which is different from the first side.

<Finisher configuration>
The configuration of the finisher 109 of the image forming apparatus 101 according to the embodiment of the invention will be described in detail with reference to FIGS. 2 and 3. FIG.

The finisher 109 includes a communication I/F 241 , a CPU 242 , a memory 243 , a paper ejection control unit 244 , a stack tray 332 , a transport sensor 333 , a transport sensor 334 , a transport sensor 335 , and a transport sensor 336 . I have. The communication I/F 241 , CPU 242 , memory 243 and paper ejection control unit 244 are connected via a system bus 245 so as to be able to communicate with each other.

A communication I/F 241 is connected to the printer 107 via a communication cable 249 and controls communication with the printer 107 . The communication I/F 241 transmits information or data input from the CPU 242 to the printing device 107 and receives information or data from the printing device 107 when the finisher 109 and the printing device 107 operate cooperatively. Output to the CPU 242 .

The CPU 242 executes control programs stored in the memory 243 . By executing the control program, the CPU 242 performs various controls necessary for paper discharge based on electrical signals input from the transport sensor 333, the transport sensor 334, the transport sensor 335, and the transport sensor 336. It directs H.244 operations.

The memory 243 stores control programs and functions as a work area when the CPU 242 executes various processes. The memory 243 can use, for example, a volatile RAM (Random Access Memory), a nonvolatile ROM (Read Only Memory), a storage, or a USB (Universal Serial Bus) memory. The memory 243 is not limited to the above, and may be any storage device for holding data or programs.

The sheet ejection control unit 244 performs control to eject the conveyed sheet based on an instruction from the CPU 242 .

A stack tray 332 stacks sheets conveyed through the conveying path 331 and discharged.

The conveying sensor 333 , the conveying sensor 334 , the conveying sensor 335 , and the conveying sensor 336 detect passage of the sheet conveyed on the conveying path 331 and output an electric signal according to the detection result to the CPU 242 .

<Configuration of Image Reading Unit>
A configuration of the image reading unit 231 of the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIGS. 2 to 4. FIG.

The image reading unit 231 has a CIS 321 and a CIS 322 .

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.

In the reading sensor 351, a plurality of light receiving elements (photoelectric conversion elements) (not shown) are arranged along the main scanning direction of the CIS 321, which is perpendicular to the sheet conveying direction. The reading sensor 351 receives light emitted from the LED 350 onto the sheet and reflected by the sheet using a plurality of light receiving elements. The plurality of light receiving elements of the reading sensor 351 read the image formed on the sheet by outputting to the CPU 222 an output value (electrical signal) corresponding to the intensity of the received reflected light.

A white reference plate 352 is a calibration member (reference member) used for shading correction of the CIS 321 .

In the CIS 321 having the above configuration, the LED 350 and the reading sensor 351 move to positions where the white reference plate 352 can be read during shading correction. Alternatively, the white reference plate 352 moves to the reading position of the LED 350 and the reading sensor 351 during shading correction. Shading correction is performed on the CIS 321 based on the reading result of the white reference plate 352 by the reading sensor 351 . Therefore, the CIS 321 cannot read the image formed on the sheet during shading correction.

The CIS 322 includes an LED 353 that serves as a light source, a reading sensor 354 that serves as a light receiving portion, and a white reference plate 355 .

The LED 353 irradiates the lower surface of the sheet with light at the timing when the sheet conveyed on the conveying path 323 reaches the reading position.

In the reading sensor 354, a plurality of light receiving elements (photoelectric conversion elements) (not shown) are arranged along the main scanning direction of the CIS 322, which is perpendicular to the sheet conveying direction. The reading sensor 354 receives light emitted from the LED 353 onto the sheet and reflected by the sheet using a plurality of light receiving elements. The plurality of light receiving elements of the reading sensor 354 read the image formed on the sheet by outputting to the CPU 222 an output value (electrical signal) corresponding to the intensity of the received reflected light.

A white reference plate 355 is a calibration member (reference member) used for shading correction of the CIS 322 .

In the CIS 322 having the above configuration, the LED 353 and the reading sensor 354 move to positions where the white reference plate 355 can be read during shading correction. Alternatively, the white reference plate 355 moves to the reading position of the LED 353 and reading sensor 354 during shading correction. Shading correction is performed on the CIS 322 based on the reading result of the white reference plate 355 by the reading sensor 354 . Therefore, the CIS 322 cannot read the image formed on the sheet during shading correction.

Note that the image reading unit 231 is not limited to being configured by the CIS 321 and CIS 322, and can be implemented by a CCD or CMOS sensor.

<Operation of Image Forming Apparatus>
The operation of the image forming apparatus 101 according to the embodiment of the invention will be described in detail.

The printing device 107 forms adjustment images for adjusting image forming conditions on both sides of the sheet. Here, the sheet on which the 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 read image of the adjustment image by the CIS 321 and CIS 322 is stored in the memory 223 . The CPU 222 refers to the memory 223, analyzes the images read by the CIS 321 and the CIS 322, feeds back the analysis results to the image forming conditions, and generates the image forming conditions.

Here, the generated image forming conditions include parameters for adjusting geometric characteristics, parameters for adjusting image density, and parameters for adjusting color misregistration. The parameters for adjusting the geometric properties of the image are, for example, the perpendicularity or the printing position of the image with respect to the sheet. Further, the adjustment image formed on the adjustment chart is an image for detecting geometric characteristics, an image for detecting image density, or an image for detecting color misregistration.

When generating parameters for adjusting the geometrical characteristics, the CPU 222 refers to the memory 223 and analyzes the images read by the CIS 321 and the CIS 322 to detect the geometrical characteristics. Then, the CPU 222 generates parameters based on the detected geometric characteristics and the ideal geometric characteristics, and performs image processing on the image data based on the generated parameters to determine the geometric characteristics of the image formed on the sheet. adjust.

Specifically, 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.

In such a case, the CPU 222 performs affine transformation on the image data so that the detected geometric characteristics become ideal geometric characteristics, and adjusts correction values for optimally correcting the geometric characteristics of the front and back images. do. The CPU 222 controls the geometric characteristics of the image formed on the sheet by forming the image on the sheet using the correction values. As a result, the printing apparatus 107 can suppress variations in geometric characteristics of images caused by variations in the internal temperature.

Further, the CPU 222 generates image forming conditions for suppressing variations in image density based on the reading result of the CIS 321 or CIS 322 when forming an adjustment image for detecting image density. The CPU 222 adjusts the image density to an ideal image density by controlling the intensity of the light source of the exposure unit 227 based on the generated 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 of the CIS 321 or CIS 322 . The CPU 222 converts the image data based on the generated gradation correction table. The printing apparatus 107 adjusts the image density to an ideal image density by forming an image on a sheet based on the image data converted by the CPU 222 .

Further, the CPU 222 generates an image forming condition for suppressing color shift based on the reading result of the CIS 321 or CIS 322 when an adjustment image for detecting color shift is formed. The CPU 222 corrects the color misregistration by controlling the position of the image formed on the photosensitive member by the exposure unit 227 based on the generated image forming conditions.

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. Here, the user image is an image included in image data transferred from the client PC 103 .

When printing the adjustment chart, the CPU 222 inserts the adjustment chart between the user image of the Nth page and the user image of the (N+1)th page each time the number of printed sheets reaches a predetermined number N from the received image data. create the image data. Further, when forming the adjustment image on the same sheet as the user image, the CPU 222 preferably forms the adjustment image in the cutting area of the sheet. By forming the adjustment image in the cutting area, the cutting area is cut by the cutting process, so the adjustment image can be easily removed from the product.

In addition, in the case of printing as an adjustment chart, the printing apparatus 107 excludes the adjustment chart from the output so that the adjustment chart is not included in the output according to the print job.

Specifically, the printing apparatus 107 switches the flapper 324 from the transport path 323 to the ejection path 326 . Then, the printing apparatus 107 discharges the adjustment chart from which the adjustment images are read by the CIS 321 and CIS 322 to the discharge tray 328 via the transport path 323 and the discharge path 326 . Further, the printing apparatus 107 switches the flapper 324 so that the sheet is conveyed from the conveying path 323 to the downstream conveying path 325 when the sheet is not the adjustment chart. The printing apparatus 107 then conveys the sheet from the conveying path 323 to the downstream conveying path 325 .

The sheet conveyed to the downstream conveying path 325 is delivered to the finisher 109 .

The finisher 109 stacks the sheets delivered from the printing apparatus 107 on the stack tray 332 via the transport path 331 . The CPU 242 determines that a transport jam occurs when the transport sensor 333, the transport sensor 334, the transport sensor 335, or the transport sensor 336 does not detect the leading edge or the trailing edge of the sheet in the transport direction even after a predetermined time has elapsed since the start of sheet transport. judge that it did. In this case, the CPU 242 notifies the printing apparatus 107 that a transport jam (transport error) has occurred in the finisher 109 .

When the printing apparatus 107 receives a notification of the occurrence of a transport jam from the finisher 109, it switches the flapper 324 to the side of the discharge path 326 regardless of whether it is an adjustment chart or not, and prints all the sheets (remaining sheets) in the machine. paper) is ejected to the ejection tray 328 . By discharging the residual paper to the discharge tray 328, the user's load of jam processing can be reduced.

<How to set both sides auto adjustment>
A setting method for front/back automatic adjustment in the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

5, FIG. 5(a) is an initial screen, FIG. 5(b) is an application mode selection screen, FIG. 5(c) is a front/back auto adjustment setting screen, and FIG. 5d) is an adjustment frequency selection screen, FIG. 5(e) is an adjustment interval setting screen, and FIG. 5(f) is an initial screen.

The image forming apparatus 101 can automatically set the correction values of the image forming conditions during printing by executing the front/back automatic adjustment process and performing the front/back automatic adjustment. A setting screen for front/back auto adjustment is displayed on the display 225 under the control of the CPU 222 . The user can set front/back auto adjustment from the setting screen using the operation unit 224 . The user can set the front/back auto adjustment before instructing execution of printing.

Specifically, when the user selects the soft key "applied mode" from the initial screen shown in FIG. 5(a), the CPU 222 displays the application mode selection screen shown in FIG. indicate.

When the user selects the soft key “Adjustment” from the application mode selection screen, the CPU 222 displays the front/back auto adjustment setting screen shown in FIG. 5C on the display 225 .

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 displays the adjustment interval setting screen shown in FIG.

When the user inputs the number of sheets for the adjustment interval using the ten keys on the adjustment interval setting screen and presses the soft key "OK", the CPU 222 enables the front/back auto adjustment. In the case of FIG. 5E, the number of sheets in the adjustment interval is set to 10 sheets. The CPU 222 adjusts the image forming conditions by creating an adjustment chart for each number of sheets in the set adjustment interval and performing front/back auto adjustment.

Note that when the user selects the soft key "cancel" from the front/back auto adjustment setting screen shown in FIG. 5(c), the CPU 222 disables the front/back auto adjustment.

When front/back auto adjustment is set, the CPU 222 displays an initial screen shown in FIG. This initial screen has 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. Further, when the front/back automatic adjustment is disabled, the CPU 222 does not perform the front/back automatic adjustment.

Such automatic front/back adjustment can also be set for an interrupt print job, which is an interrupt process. If the user presses the interrupt button 602 during printing, an interrupt print job is set. After pressing the interrupt button 602 , the user activates the front/back auto adjustment, sets the adjustment interval to a predetermined number of sheets (for example, 5), and presses the print button 601 . As a result, an adjustment chart is created every predetermined number of sheets (for example, every five sheets) during printing by an interrupt print job.

<Information when executing a print job>
Information when executing a print job in the image forming apparatus 101 according to the embodiment of the present invention will be described in detail.

Information for executing a print job includes job information and front/back auto adjustment information. First, job information will be described in detail with reference to FIG.

Job information is stored in the memory 223 by the CPU 222 in response to input of a print job or an interrupt print job to the printing apparatus 107 .

The job information is managed by a job ID, and 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, as shown in FIG.

The paper feed deck ID indicates a paper feed deck that feeds sheets according to the input print job. The number of sheets in the adjustment interval is the number of sheets in the adjustment interval set on the adjustment interval setting screen shown in FIG. 5(e). The front/back automatic adjustment flag indicates a setting state such as whether the front/back automatic adjustment is enabled or disabled. For example, the front/back automatic adjustment flag is set to "1" when the front/back automatic adjustment is enabled, and is set to "0" when the front/back automatic adjustment is disabled.

The interrupt print flag indicates whether or not an interrupt print job has been input. For example, the interrupt print flag is set to "1" when an interrupt print job is input, and is set to "0" when no interrupt print job is input. The previous job ID is the job ID of the interrupted print job when the interrupt print job is input.

Next, the front/back automatic adjustment information will be described in detail with reference to FIG.

The front/back auto adjustment information includes front/back auto adjustment information for the first paper feed deck 301 to front/back auto adjustment information for the n-th (n is an integer equal to or greater than 2) paper feed deck. In the case of the printing device 107 shown in FIG. 3, n is two.

The front/back automatic adjustment information of the first paper feeding deck 301 includes a first paper feeding deck ID 801, a front/back registration main scanning offset value 802, a front/back registration sub-scanning offset value 803, an adjustment execution number of sheets 804, an adjustment execution time 805, and an adjustment execution temperature 806. contains.

The first paper feed deck ID 801 indicates that the front/back auto adjustment information is for the first paper feed deck 301 .

A front/back registration main scanning offset value 802 and a front/back registration sub-scanning offset value 803 are correction values for each paper feed deck. The front/back registration main scanning offset value 802 and the front/back registration sub-scanning offset value 803 are correction values for adjusting (offset) the image writing position for each of the front and back surfaces of the sheet when they are correction values for geometric characteristics. The correction value adjusted by the front/back automatic adjustment is set for each paper feeding deck from the front/back automatic adjustment information of the first paper feeding deck 301 to the front/back automatic adjustment information of the n-th paper feeding deck. The correction value for each paper feed deck is stored in the memory 223 as front/back auto adjustment information, for example.

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 first paper feed deck 301, the CPU 222 reads out 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 from the memory 223. . Then, the CPU 222 offsets the image writing position based on the front/back registration main scanning offset value 802 and the front/back registration sub-scanning offset value 803 that have been read. The readout front/back registration main scanning offset value 802 and front/back registration subscanning offset value 803 are updated based on the result of reading the adjustment image.

The number of sheets to be adjusted 804 is the total cumulative number of printed sheets at the time when the front/back auto adjustment is executed.

The CPU 222 counts the total number of printed sheets of the printing apparatus 107 and sets the counted total number of printed sheets as the adjusted number of sheets 804 .

The adjustment execution time 805 holds the time that the CPU 222 acquired from the timer 251 when the front/back automatic adjustment was executed.

The adjustment execution temperature 806 holds the measurement result of the internal temperature obtained by the CPU 222 from the temperature sensor 252 when the front/back automatic adjustment is executed.

Note that the front/back automatic adjustment information for the n-th paper feeding deck is the same as the front/back automatic adjustment information for the first paper feeding deck 301, so a detailed description thereof will be omitted.

<Adjustment image>
An adjustment image formed by the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG. The adjustment image shown in FIG. 8 is an adjustment image for adjusting geometric characteristics.

When the front/back auto adjustment is enabled, the CPU 222 creates an adjustment chart by printing an adjustment image on a sheet every number of sheets set in the adjustment interval. The adjustment images of the adjustment chart are formed at the four corners of the adjustment chart, as shown in FIG. 8, for example. Note that the adjustment images formed together with the user image are also formed at the four corners of the user image as shown in FIG.

The CIS 321 reads the adjustment image of the adjustment chart, and the CIS 322 reads the backside adjustment image of the adjustment chart. The CPU 222 calculates the displacement amount of the adjustment image from the reference position based on the reading result of the adjustment image by the CIS 321 and CIS 322, and determines the geometric characteristic correction value for correcting the calculated displacement amount.

The CPU 222 updates the front/back automatic adjustment information stored in the memory 223 with the determined correction value of the geometric characteristic. For example, when paper is fed from the first 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 of the front/back auto adjustment information stored in the memory 223 .

<Both sides auto adjustment>
The automatic front/back adjustment performed by the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 9, FIG. 9(a) shows a general case in which there is no interruption when performing front/back auto adjustment during printing of print job A for which front/back auto adjustment is enabled. FIG. 9B shows that when printing of the adjustment chart is interrupted during execution of front/back auto adjustment after printing job A for which front/back auto adjustment is enabled, the time required to return from the interruption is predetermined. Indicates the case of more than an hour. FIG. 9C shows that when printing of the adjustment chart is interrupted during execution of front/back auto adjustment after printing job A for which front/back auto adjustment is enabled, the time required to return from the interruption is predetermined. Less than hours are indicated.

FIG. 9 illustrates an example in which three adjustment charts (interruption adjustment charts) to be interrupted between print jobs are inserted and subsequent print jobs are executed. Note that the number of adjustment charts to be inserted is not limited to three, and can be any number of sheets as long as the correction value (front/back correction value) obtained as a result of the front/back auto adjustment using the adjustment chart is reflected in the product. It's okay.

First, a general case in which there is no interruption when executing front/back auto adjustment during printing of print job A for which front/back auto adjustment is enabled will be described with reference to FIG. 9(a).

When the user looks at the display 225 and sets the adjustment interval to 100 sheets using the operation unit 224, three adjustment charts are inserted before the execution of the printing of the 101st page from the previous adjustment of print job A. , and then the 101st and subsequent pages are printed.

Here, when the correction value up to the 100th page is "3", the correction value calculated using the three adjustment charts is applied to the 101st page and thereafter. In FIG. 9A, the correction value calculated using the three adjustment charts is "5", and the calculated correction value "5" is applied to the correction value of the 101st page. By using such correction values, printing of the product is performed under optimum image forming conditions.

In FIG. 9A, the correction values are applied from the 101st page immediately after adjustment. However, if it is difficult to apply the correction value from the sheet immediately after adjustment, such as when the sheet conveying path is long and there are a plurality of sheets being conveyed inside the machine, the A correction value may be applied.

Next, the operation after returning from the interruption caused by the device during the front/back auto adjustment using the adjustment chart that is interrupted in the middle of the print job is shown in the figure. 9(b) and FIG. 9(c).

Here, the interruption caused by the apparatus occurs when the sheets accommodated in the first sheet feeding deck 301 or the second sheet feeding deck 302 run out, or when the toner, which is the developer, runs out. Alternatively, interruption caused by the device occurs when the discharge tray 328 or the stack tray 332 is full of sheets, or when a jam occurs during sheet conveyance. Note that the interruption caused by the apparatus is not limited to the above case, and any event that causes printing to be interrupted may be used.

First, when the printing of the adjustment chart is interrupted during the execution of both sides auto adjustment after printing job A for which both sides auto adjustment is enabled, and the time from interruption to recovery is longer than a predetermined time. This will be explained with reference to FIG. 9(b).

When the front/back auto adjustment after printing the 100th page of print job A is interrupted during calculation of the correction value, the CPU 222 determines the interruption time from the time of interruption to the time of recovery based on the timing result of the timer 251. . Specifically, the CPU 222 calculates and determines the interruption time from the difference between the interruption time saved in the memory 223 and the return time obtained from the timer 251 .

When the determined interruption time is longer than or equal to the predetermined time, the CPU 222 inserts the adjustment chart again before printing the 101st page of the print job A after returning, performs front/back auto adjustment from the beginning, and then executes the print job. The 101st page of A is printed. The predetermined time is exemplified here as one hour. In this case, the CPU 222 performs front/back auto adjustment using the adjustment chart according to the configuration of the image processing system 1, printing conditions such as the environmental temperature or job type, or interruption conditions such as no paper in the paper feed deck. You can decide whether or not

In FIG. 9B, the correction value calculated using the three adjustment charts inserted after returning is "6", and the calculated correction value "6" is used as the correction value for the 101st page. Apply. By using such correction values, printing of the product is performed under optimum image forming conditions.

Next, when the printing of the adjustment chart is interrupted during the execution of the front/back auto adjustment after printing the print job A for which the front/back auto adjustment is enabled, and the time taken to return from the interruption is less than the predetermined time. This will be explained with reference to FIG. 9(c).

When the determined interruption time is less than the predetermined time, the CPU 222 executes printing of the 101st page of print job A using the correction value obtained from the result of the front/back automatic adjustment performed immediately before the interruption. The predetermined time is exemplified here as one hour. The interruption time can be calculated by the same method as in the case of FIG. 9(b).

In FIG. 9C, the correction value calculated using the adjustment chart in the front/back auto adjustment performed immediately before the interruption is "5", and the calculated correction value "5" is Applies to correction values. By using such a correction value, printing of a product is performed under optimum image forming conditions while suppressing downtime.

In the above operation, the CPU 222 holds the correction value, execution time of the last adjustment execution, the total number of printed sheets, and the internal temperature in the memory 223 for each paper feed deck. Then, the CPU 222 determines the elapsed time from the previous front/back automatic adjustment for each paper feed deck.

It should be noted that the CPU 222 may determine the elapsed time since the previous front/back auto adjustment in common for each paper feed deck in the case of a correction value that does not depend on the paper feed deck. In addition, when a plurality of paper feed decks are dependent on each other, the CPU 222 may determine the elapsed time from the previous front/back auto adjustment in consideration of the dependency.

Further, when the paper feed deck can be set for each print job, the CPU 222 determines whether or not to insert the adjustment chart at the beginning of the print job. In this case, the CPU 222 may determine whether or not to insert the adjustment chart each time the paper feed deck for the sheet to be printed is switched when the correction value is different for each paper feed deck.

<Image forming processing>
Image forming processing executed by the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

The image forming process shown in FIG. 10 is started when the printing apparatus 107 receives a print job start instruction from the operation unit 224 or the client PC 103 .

First, the CPU 222 starts printing according to the content of the print job (S1).

Next, the CPU 222 increments an adjustment execution counter (not shown) (S2). Here, the adjustment execution counter value counted by the adjustment execution counter represents the accumulated number of printed user images after the front/back automatic adjustment is executed.

Next, the CPU 222 determines whether or not the adjustment execution counter value has reached the adjustment execution number of sheets for which adjustment should be executed (S3).

When the adjustment execution counter value reaches the adjustment execution number (S3: Yes), the CPU 222 executes the front/back auto adjustment process (S4). When the front/back auto adjustment process is interrupted during the formation of the adjustment image or the reading of the adjustment image, the print job starts after returning from the interruption according to the interruption time from the time of interruption to the time of return. This is processing for determining whether or not to adjust the image forming conditions before. The details of the front/back automatic adjustment process will be described later.

Next, the CPU 222 clears the adjustment execution counter (S5).

Next, the CPU 222 determines whether or not there is an interruption factor (S6). Here, the interruption factor is, for example, when there are no more sheets accommodated in the first sheet feeding deck 301 or the second sheet feeding deck 302, or when toner, which is developer, runs out. Alternatively, the interruption factor is, for example, when the discharge tray 328 or the stack tray 332 is full of sheets, or when a jam occurs during sheet conveyance. Note that the interruption factor is not limited to the above, and may be any event as long as it causes printing to be interrupted.

If there is an interruption factor (S6: Yes), the CPU 222 interrupts the print job (S7).

Next, the CPU 222 determines whether or not the interruption factor has been resolved (S8). Here, elimination of the cause of interruption means that a response corresponding to the cause of interruption has been implemented and completed. For example, when the cause of interruption is that the sheets contained in the first sheet supply deck 301 or the second sheet supply deck 302 have run out, the interruption factor can be resolved by the user. This is the supply of sheets to the paper deck 302 . Further, when the cause of interruption is that the stack tray 332 is full of sheets, the cancellation of the cause of interruption is removal of the sheets from the stack tray 332 by the user.

CPU222 repeats the process of step S8, when the interruption factor is not eliminated (step S8: No).

On the other hand, when the interruption factor has been eliminated (step S8: Yes), the CPU 222 determines whether printing based on the print job has been completed (S9).

When the printing is completed (step S9: Yes), the CPU 222 ends the print job and ends the image forming process.

On the other hand, in step S3, when the adjustment execution counter value has not reached the adjustment execution number (S3: No), the CPU 222 skips to the process of step S6.

Further, in step S6, the CPU 222 skips to the process of step S9 when there is no interruption factor (S6: No).

Further, in the processing of step S9, if the printing is not completed (step S9: No), the CPU 222 returns to the processing of step S1 to execute the next printing based on the content of the print job.

<Both sides auto adjustment processing>
The front/back automatic adjustment process executed by the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

The front/back auto adjustment process shown in FIG. 11 is started when the adjustment execution counter value reaches the adjustment execution number in the process of step S3 in FIG. 10 (step S3: Yes).

First, the CPU 222 prints an adjustment chart on a sheet (S11).

Next, the CIS 321 and CIS 322 of the image reading unit 231 read the adjustment image of the printed adjustment chart (S12).

Next, the CPU 222 records the read data of the adjustment image of the adjustment chart read by the CIS 321 and CIS 322 in the memory 223 (S13).

Next, the CPU 222 increments a read number counter (not shown) (S14). The number-of-reads counter counts the number of adjustment charts on which read data is recorded.

Next, the CPU 222 determines whether or not there is an interruption factor (S15).

If there is an interrupt factor (step S15: Yes), the CPU 222 interrupts the front/back auto adjustment operation (S16).

Next, the CPU 222 saves the interruption time when the interruption was made in the memory 223 (S17).

Next, the CPU 222 determines whether or not the interruption factor has been resolved (S18). At this time, the CPU 222 issues a release instruction to the user through the display 225 according to the interruption factor. The CPU 222 prompts the first sheet feeding deck 301 or the second sheet feeding deck 302 to replenish the sheets when, for example, the cause of the interruption is that the first sheet feeding deck 301 or the second sheet feeding deck 302 runs out of sheets. The display is caused to appear on the display 225 . Further, the CPU 222 causes the display 225 to display a display prompting the user to remove the sheets when, for example, the interruption factor is that the stack tray 332 is full of sheets.

CPU222 repeats the process of step S18, when the interruption factor is not eliminated (S18:No).

On the other hand, when the cause of interruption has been resolved (S18: Yes), the CPU 222 performs an interruption time interval determination process for determining the time from the start of interruption to the cancellation of interruption (S19). Details of the interruption time interval determination process will be described later.

Next, the CPU 222 determines whether or not the read number counter clear flag set by executing the interruption time interval determination process is "1" (S20). The number-of-reads counter clear flag determines whether or not it is necessary to perform front/back auto adjustment using an adjustment chart before executing a print job, or whether or not a correction value is to be calculated from the result of front/back auto adjustment performed before interruption. is a flag for

When the read number counter clear flag is "0" (step S20: No), the CPU 222 calculates a correction value using the read data and reflects the calculated correction value (S21).

Next, the CPU 222 clears the number-of-reads counter (S22), and then ends the front/back auto adjustment process. After that, the CPU 222 executes the process of step S5 in FIG.

On the other hand, in the process of step S15, if there is no interrupting factor (step S15: No), the CPU 222 determines whether the read number counter value counted by the read number counter (not shown) has reached the reading completion number (S23). . The number of read-completed sheets is the number of sheets determined for performing the front/back auto adjustment, and 3 sheets are exemplified here.

If the number of read sheets counter value has not reached the number of sheets that have been read (S23: No), the CPU 222 returns to the process of step S11 to print the next adjustment chart.

On the other hand, when the number of read sheets counter value reaches the read number of sheets (S23: Yes), the CPU 222 calculates a correction value using the read data and reflects the calculated correction value (S21).

If the number-of-reads counter clear flag is "1" (step S20: Yes), the CPU 222 clears the number-of-reads counter (S24). return to the process of

<Interruption time interval determination processing>
Interruption time interval determination processing executed by the image forming apparatus 101 according to the embodiment of the present invention will be described in detail with reference to FIG.

The interruption time interval determination process shown in FIG. 12 is started when the cause of printing interruption is eliminated in the process of step S18 of FIG.

First, the CPU 222 clears (initializes) the number-of-reads counter clear flag (S31).

Next, as described with reference to FIG. 9B, the CPU 222 acquires from the memory 223 the time information of the time when the interruption occurred, and acquires the current time from the timer 251 ( S32).

Next, the CPU 222 determines whether or not the time difference between the acquired time information at the time of interruption and the current time is greater than or equal to a predetermined threshold (predetermined time or longer) (S33). Thereby, the CPU 222 determines whether or not a predetermined time interval or more has passed since the interruption occurred.

If the time difference is equal to or greater than the predetermined threshold (S33: Yes), the CPU 222 sets the number-of-reads counter clear flag to "1" (clears the number-of-reads counter because front/back auto adjustment is required before starting the print job). Flag=1) (S34). After that, the CPU 222 ends the interruption time interval determination process and executes the process of step S20 in FIG.

On the other hand, if the time difference is less than the predetermined threshold value (S33: No), the CPU 222 sets the number-of-reads counter clear flag to "0" (the Counter clear flag=0) (S35). After that, the CPU 222 ends the interruption time interval determination process and executes the process of step S20 in FIG.

As described above, according to the present embodiment, even if an interruption occurs during the execution of the front/back auto adjustment, the necessary number of adjustment charts is used to perform the optimum adjustment at the optimum printing interval. can be used to calculate the correction value. As a result, it is possible to perform printing under optimum image forming conditions (correction values).

In the present embodiment, when an interruption occurs during the formation of an adjustment image or during the reading of an adjustment image, a print job is started after recovery from the interruption according to the interruption time from the time of interruption to the time of return. It is determined whether or not to adjust the image forming conditions before. This makes it possible to always form an image on the sheet under optimum image forming conditions.

It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the gist of the present invention.

Specifically, in the above-described embodiment, the interruption time interval is used as a determination condition. It may be determined whether or not to perform front/back automatic adjustment using the adjustment chart.

Further, in the above-described embodiment, front/back auto adjustment is performed, but the present invention is not limited to this, and adjustment such as image gradation correction using a plurality of gradation images, for example, may be performed.

1 image processing system 101 image forming apparatus 102 external controller 103 client PC
107 Printer 109 Finisher 221 Storage 222 CPU
223 memory 224 operation section 225 display 227 exposure section 228 image forming section 229 fixing section 230 paper feeding section 231 image reading section 232 image processing section 251 timer 252 temperature sensor 301 first paper feeding deck 302 second paper feeding deck 304 image forming section 305 image forming unit 306 image forming unit 307 image forming unit 308 intermediate transfer belt 309 secondary transfer roller 310 primary transfer roller 350 LED
351 reading sensor 352 white reference plate 353 LED
354 reading sensor 355 white reference plate

Claims (3)

An image forming apparatus that forms an image on a sheet based on image forming conditions,
an image forming means for forming an adjustment image on a sheet;
reading means for reading the adjustment image formed on the sheet by the image forming means;
control means for generating the image forming conditions based on the reading result of the adjustment image read by the reading means;
a clocking means for clocking time;
has
The control means is
determining an interruption time from an interruption during the formation of the adjustment image by the image forming means or the reading of the adjustment image by the reading means to recovery based on the time measurement result of the time measurement means; controlling whether or not the image forming means forms the adjustment image before starting the print job after returning from the interruption, based on the interruption time;
An image forming apparatus characterized by: The control means is
2. The image forming apparatus according to claim 1, wherein the image forming device is caused to form the adjustment image when the interruption time is equal to or longer than a predetermined time. The control means is
generating the image forming condition based on the reading result before the interruption without causing the image forming means to form the adjustment image when the interruption time is less than a predetermined period of time;
3. The image forming apparatus according to claim 1, wherein:

Images