JP2021133547A - Image forming device - Google Patents

Abstract

An object of the present invention is to have means for switching whether or not to perform an inspection process, and to improve both the inspection accuracy of print jobs that are inspected and the throughput of print jobs that are not inspected. [Solution] The image forming apparatus includes a printing means, a conveyance means for conveying paper on which an image is printed, a reading means for reading the image on the paper conveyed from the printing means, and an image obtained by reading the image with the reading means. an inspection means for executing an inspection process for inspecting the presence or absence of printing defects based on the image data obtained, paper that has undergone the inspection process and has not been determined to have a printing defect, paper that has undergone the inspection process and has been determined to have a printing defect; , a paper ejecting unit including a plurality of ejection trays for ejecting sheets for which the inspection process has not been performed; and a paper conveyance speed in a print job in which the inspection process is not performed is set to a print job in which the inspection process is performed. and control means for controlling the conveyance speed of the conveyance means to be higher than the conveyance speed of the paper in the paper conveyance speed. [Selection diagram] Figure 10

Description

The present invention relates to an image forming apparatus.

In the field of commercial printing, there is known a system in which an inspection device is connected downstream in the transport direction of an image forming unit that forms an image on paper, and the printed matter on which the image is formed is inspected by the inspection device. The inspection device reads the image formed on each paper by the reading unit, and inspects whether stains or printing defects have occurred, so that the inspection process is performed by comparing with the abnormality reference image. When a printing defect is found in such an inspection process, the paper is discharged to a paper destination different from the original paper discharge destination (see Patent Document 1).

Generally, in the field of commercial printing, various post-processing such as staples, punches, and bookbinding are required. At the same time, higher throughput is also required. When performing post-processing, the space between papers is increased in order to secure time for performing post-processing. Therefore, in order to widen the paper spacing while maintaining high throughput, it is effective to increase the paper transport speed as much as possible when transporting the paper from the image forming apparatus to the apparatus connected downstream thereof.

By the way, the inspection process by the inspection device tends to require higher accuracy. The inspection device often uses a sensor such as CIS as a reading unit for reading an image of a product, but the higher the reading resolution, the finer the stains and printing defects can be detected. Further, it is possible to improve the inspection accuracy by reading with a high reading resolution and performing resolution conversion processing on the obtained image data to remove moire. As described above, in order to improve the inspection accuracy of the inspection apparatus, it is preferable to read the image with a higher resolution.

Japanese Unexamined Patent Publication No. 2013-166296

As described above, it is effective from the viewpoint of improving the throughput that the paper transport speed at the time of transporting from the image forming apparatus to the device downstream thereof is as high as possible. However, the higher the paper transport speed, the greater the amount of image data read by the reading unit in the inspection device per unit time. As the amount of data increases, the inspection device must be equipped with a high-performance CPU having a high clock frequency, which causes an increase in cost.

Further, when the reading resolution is increased in order to improve the inspection accuracy, the inspection apparatus handles a large amount of data, which requires a large-capacity memory and registers and circuits associated with them, which also causes an increase in cost.

By the way, in the field of commercial printing, it is not always necessary to inspect the deliverables, and there are cases where a certain number of printed matter that does not require inspection is handled. For users who handle both printed matter that requires inspection and printed matter that does not require inspection, an expensive inspection device that can read at high resolution even at a high transport speed is not worth the cost performance. ..

The present invention has been made in view of the above problems, and an object of the present invention is to provide a means for improving the throughput of a print job that does not perform inspection processing while suppressing an increase in cost of an inspection apparatus. It is in.

In order to achieve the above object, the image forming apparatus according to one aspect of the present invention includes a printing means for printing an image on paper and a transport for transporting the paper on which the image is printed by the printing means along a transport path. The means, a reading means arranged downstream of the printing means in the paper conveying direction and reading an image on the paper conveyed from the printing means at a predetermined reading resolution, and the reading means obtained by reading the image. The inspection means that inspects the presence or absence of printing defects based on the image data and the transport speed when transporting the paper in the transport path in the print job that does not perform the inspection process are determined in the print job that performs the inspection process. A control means for controlling the transfer means so as to be faster than the transfer speed when the paper is conveyed in the transfer path.
It is characterized by having.

According to the present invention, it is possible to improve the throughput of a print job that does not perform inspection processing while suppressing an increase in cost of an inspection apparatus.

Overall configuration of the printing system The figure which shows the hardware configuration of an image forming apparatus Cross-sectional view of the image forming apparatus Example of setting screen for setting whether to perform inspection Flow chart showing the operation of the image forming apparatus A flowchart showing an operation of determining a transport speed in an image forming apparatus and an inspection apparatus. Flow chart showing the printing process of the image forming apparatus Flow chart showing the operation of the inspection device Flow chart showing the inspection process of the inspection device A flowchart showing the operation of the image forming apparatus in the second embodiment. Flow chart for determining whether or not to set the transport speed in the second embodiment Flow chart for determining the transport speed in the second embodiment Flow chart showing the operation of the inspection device in the second embodiment The figure which shows the paper transport interval before and after switching the presence or absence of inspection processing The figure which shows the paper transport interval before and after switching the presence or absence of inspection processing in Example 2. The figure which shows the operation when the presence / absence of inspection processing is switched in a comparative example. The figure which shows the operation when the presence / absence of inspection is switched in Example 2.

Hereinafter, the image forming apparatus 101 of the embodiment included in the present disclosure will be described with reference to the drawings.

[Outline configuration of image processing system]
FIG. 1 is a diagram showing an overall configuration of the image processing device 101. The image forming apparatus 101 includes a printing apparatus 107, an inspection apparatus 108, and a large-capacity stacker 109. The printing device 107 prints an image on a sheet of paper, and conveys the sheet on which the image is printed to an inspection device 108 arranged downstream in the conveying direction. The inspection device 108 reads the image formed on the paper conveyed from the printing device 107 by the CIS units 321 and 322, which are examples of the image reading means. Then, the presence or absence of printing defects is inspected by comparing the image data obtained by reading with the reference image registered in advance. Then, the paper is conveyed to the large-capacity stacker 109 arranged further downstream in the conveying direction. The large-capacity stacker 109 is a paper ejection device having two ejection trays, a stack tray 331 which is an example of a first ejection tray and an escape tray 324 which is an example of a second ejection tray. The large-capacity stacker 109 ejects paper that is not determined to be printing defective in the inspection process, that is, a product that is determined to be OK in the inspection result, to the stack tray 331. On the other hand, the large-capacity stacker 109 ejects the paper determined to be printing defective, that is, the paper determined to be NG in the inspection result, to the escape tray 324. The image forming apparatus 101 shown in FIG. 1 will be described as an example of a configuration including a printing apparatus 107, an inspection apparatus 108, and a large-capacity stacker 109. A post-processing device having a post-processing function may be further connected.

The image forming apparatus 101 is communicably connected to the external controller 102 via the internal LAN 105 or the video cable 106. The image forming apparatus 101 receives image data from the external controller 102, and prints an image on paper based on the received image data. The external controller 102 is communicably connected to the client PC 103 via the external LAN 104, and the client PC 103 issues a print instruction to the external controller 102.

A printer driver having a function of converting document data into a print description language (PDL) that can be processed by the external controller 102 is installed in the client PC 103. The user can issue print instructions from various applications via the printer driver. The printer driver transmits the print data described in PDL to the external controller 102 based on the print instruction from the user. When the external controller 102 receives the print data from the client PC 103, the external controller 102 performs data analysis and rasterization processing, and transmits the image data to the image forming apparatus 101.

The configuration of the image forming apparatus 101 will be described with reference to FIGS. 2 and 3. In this embodiment, the image forming apparatus using the electrophotographic method will be described as an example, but an image forming apparatus using an inkjet method or an image forming apparatus of another type may be used.

First, the printing device 107 in the image forming device 101 will be described. The printing apparatus 107 includes a laser exposure unit 227, an image forming unit 228, a fixing unit 229, and a transport unit 23. The laser exposure unit 227 is a unit that performs primary charging for irradiating a photosensitive drum with laser light to transfer a toner image and laser exposure. The laser exposure unit 227 first performs primary charging to charge the surface of the photosensitive drum to a uniform negative potential. Next, the laser driver irradiates the photosensitive drum with the laser beam while adjusting the reflection angle with the polygon mirror. As a result, the negative charge of the irradiated portion is neutralized, and an electrostatic latent image is formed. The image forming unit 228 is a device for transferring toner to paper, and is composed of a developing unit, a transfer unit, a toner replenishing unit, and the like, and transfers toner on a photosensitive drum to paper. The developing unit attaches negatively charged toner from the developing cylinder to the electrostatic latent image on the surface of the photosensitive drum to make it a visible image. The transfer unit performs primary transfer by applying a positive potential to the primary transfer roller and transferring the toner on the surface of the photosensitive drum to the transfer belt. Further, the transfer unit performs secondary transfer by applying a positive potential to the secondary transfer outer roller and transferring the toner on the transfer belt to the paper. The fixing unit 229 is a device for melting and fixing the toner on the paper to the paper by heat and pressure, and is composed of a heater, a fixing belt, a pressure belt, and the like. The transport unit 230 is a device for feeding and transporting paper, and the paper feeding operation and the transport operation are controlled by rollers and various sensors. The transport unit 230 includes transport rollers such as transport rollers 314-1, 314-2, and 314-3, and the transport speed is controlled by the CPU 222 depending on whether or not an inspection process described later is performed.

Next, the inspection device 108 will be described. The inspection device 108 reads the image on the paper conveyed from the printing device 107, and compares the read image with the pre-registered reference image. As a result, it is inspected whether there are any streaks on the paper or misalignment of the image. The inspection device 108 is arranged so that the CIS unit 321 and the CIS unit 322 face each other. The CIS unit 321 is a reading means for reading an image formed on the upper surface of the paper. The CIS unit 322 is a reading means for reading an image formed on the lower surface of the paper. The inspection device 108 uses the CIS unit 321 and the CIS unit 322 to read the image on the paper at the timing when the paper conveyed along the transfer path 323 reaches a predetermined position, and determines whether or not there is a printing defect. The CIS unit is an example of an image reading means, and may be another optical system sensor such as a CCD or CMOS.

The inspection device 108 further includes a display unit 236 for displaying the inspection result in the inspection process. The inspection result is, for example, information on inspection OK / NG in a print job, the number of pages determined to be printing defects, the number of pages, the number of inspection results NG for each inspection item, and the like. The inspection device 108 displays these inspection results on the display unit 236. Further, the inspection device 108 has transfer rollers 323-1, 323-2, 323-3, 323-4, and the transfer speed is controlled by the CPU 233 depending on whether or not the inspection process described later is performed.

The large-capacity stacker 109 is an ejection device for ejecting the inspected paper by the inspection apparatus 108. The large-capacity stacker 109 has a stack tray 331 and an escape tray 324, and ejects the deliverables determined to be OK in the inspection result to the stack tray 331, and ejects the paper determined to be printing defective to the escape tray 324.

The printing system described with reference to FIG. 1 has a configuration in which an external controller 102 is connected to the image forming apparatus 101, but the present invention is not limited to a configuration in which the external controller 102 is connected. For example, the image forming apparatus 101 may be connected to the external LAN 104 and the print data may be directly received from the client PC 103. In this case, the image forming apparatus 101 performs data analysis and rasterization processing, and executes printing processing.

[Image processing system block diagram]
FIG. 2 is a control block diagram of the image forming apparatus 101, the external controller 102, and the client PC 103.

First, the control configuration of the printing apparatus 107 will be described. The printing device 107 includes a communication I / F217, a LANI / F218, a video I / F220, an HDD221, a CPU222, a memory 223, an operation unit 224, and a display 225. Further, the printing apparatus 107 includes a laser exposure unit 227, an image forming unit 228, a fixing unit 229, and a paper feeding unit 230. Each component is connected via the system bus 231.

The communication I / F 217 is connected to the inspection device 108 and the large-capacity stacker 109 via the communication cable 249, and communication for controlling each device is performed. The LANI / F218 is connected to the external controller 102 via the internal LAN 105, and communication such as print data is performed. The video I / F 220 is connected to the external controller 102 via the video cable 106, and communication such as image data is performed.

HDD 221 is a storage device that stores programs and data. The CPU 222 executes a program stored in the HDD 221 to control image processing and printing. The memory 223 stores programs and image data required when the CPU 222 performs various processes, and also operates as a work area. The operation unit 224 receives input of various settings and operation instructions from the user. The display 225 displays the setting information of the image forming apparatus 101, the processing status of the print job, and the like. The laser exposure unit 227 is a device that performs primary charging for irradiating a photosensitive drum with laser light to transfer a toner image and laser exposure. In the laser exposure unit 227, first primary charging is performed to charge the surface of the photosensitive drum to a uniform negative potential. Next, the laser driver irradiates the photosensitive drum with the laser beam while adjusting the reflection angle with the polygon mirror. As a result, the negative charge of the irradiated portion is neutralized, and an electrostatic latent image is formed. The image forming unit 228 is a device for transferring toner to paper, and is composed of a developing unit, a transfer unit, a toner replenishing unit, and the like, and transfers toner on a photosensitive drum to paper. In the developing unit, the negatively charged toner from the developing cylinder is attached to the electrostatic latent image on the surface of the photosensitive drum to make it a visible image. In the transfer unit, a positive potential is applied to the primary transfer roller to transfer the toner on the surface of the photosensitive drum to the transfer belt, and a positive potential is applied to the secondary transfer outer roller to transfer the toner on the transfer belt to the paper. The next transcription is performed. The fixing unit 229 is a device for melting and fixing the toner on the paper to the paper by heat and pressure, and is composed of a heater, a fixing belt, a pressure belt, and the like. The paper feeding unit 230 is a device for feeding paper, and the paper feeding operation and the paper feeding operation are controlled by rollers and various sensors.

Next, the configuration of the inspection device 108 will be described. The inspection device 108 of the image forming device 101 is composed of a communication I / F 232, a CPU 233, a memory 234, an image reading unit 235, a display unit 236, an operation unit 237, and an image processing unit 250, and each component is via a system bus 238. Is connected. The communication I / F 232 is connected to the printing device 107 via the communication cable 249, and the communication required for control is performed. The CPU 233 performs the control necessary for the inspection according to the program stored in the memory 234. The memory 234 is a storage device for storing a program. The image reading unit 235 reads the image on the conveyed paper based on the instruction of the CPU 233. The CPU 233 compares the image read by the image reading unit 235 with the pre-registered reference image stored in the memory 234, and determines whether the printed image is normal or not.

The reference image is separately printed before starting the print job, and the printed image is read and registered by the inspection device 108. Regarding this, a configuration using an image obtained by RIP processing the print job input from the client PC 103 may be used.

The display unit 236 displays the inspection result and the setting screen. The operation unit 237 is operated by the user and receives instructions such as changing the setting of the inspection device 108 and registering the reference image. The image processing unit 250 sets the gain adjustment value by reading the image of the image reading unit 235 and reflects it in the image reading result.

Next, the configuration of the large-capacity stacker 109 will be described. The large-capacity stacker 109 is composed of a communication I / F 239, a CPU 240, a memory 241 and a paper ejection control unit 242, and each component is connected via a system bus 243. The communication I / F 239 is connected to the printing device 107 via the communication cable 249, and the communication required for control is performed. The CPU 240 executes a program stored in the memory 241 and performs various controls necessary for paper ejection. The memory 241 is a storage device that stores a computer-readable program. The paper ejection control unit 242 controls to eject the conveyed paper to the stack tray 331 or the escape tray 334 based on the instruction from the CPU 240.

Next, the configuration of the external controller 102 will be described. The external controller 102 is composed of a CPU 208, a memory 209, an HDD 210, a keyboard 211, a display 212, a LANI / F213, a LANI / F214, and a video I / F215, and is connected through a system bus 216. The CPU 208 comprehensively executes processing such as reception of print data from the client PC 103, RIP processing, and transmission of print data to the image forming apparatus 101 based on the programs and data stored in the HDD 210. The memory 209 stores programs and data necessary for the CPU 208 to perform various processes, and operates as a work area. The HDD 210 stores programs and data necessary for operations such as printing processing. The keyboard 211 is a device for inputting an operation instruction of the external controller 102. Information such as an execution application of the external controller 102 is displayed on the display 212 by video signals of a still image or a moving image. The LANI / F213 is connected to the client PC 103 via the external LAN 104, and communication such as a print instruction is performed. The LANI / F214 is connected to the image forming apparatus 101 via the internal LAN 105, and communication such as printing instructions is performed. The video I / F 215 is connected to the image forming apparatus 101 via a video cable 106, and communication such as print data is performed.

Next, the configuration of the client PC 103 will be described. The client PC 103 is composed of a CPU 201, a memory 202, an HDD 203, a keyboard 204, a display 205, and a LANI / F 206, and is connected via the system bus 207. The CPU 201 creates print data and executes print instructions based on a document processing program or the like stored in the HDD 203. Further, the CPU 201 comprehensively controls each device connected to the system bus. The memory 202 stores programs and data required when the CPU 201 performs various processes, and operates as a work area. The HDD 203 stores programs and data necessary for operations such as printing processing. The keyboard 204 is a device for inputting operation instructions of the client PC 103. Information such as an execution application of the client PC 103 is displayed on the display 205 by video signals of a still image or a moving image. The LANI / F206 is connected to the external LAN 104, and communication such as printing instructions is performed.

In the above description, the external controller 102 and the image forming apparatus 101 are connected to the internal LAN 105 and the video cable 106. However, any configuration may be used as long as the data required for printing can be transmitted and received, and for example, only the video cable may be connected. .. Further, the memory 202, the memory 209, the memory 223, the memory 234, the memory 241 and the memory 246 may be storage devices for storing data or programs, respectively. For example, a configuration may be substituted with a volatile RAM, a non-volatile ROM, an internal HDD, an external HDD, a USB memory, or the like.

[Basic image forming operation of image forming apparatus]
FIG. 3 is a cross-sectional view of the image forming apparatus 101. The printing device 107 has a paper feed deck 301 and a paper feed deck 302 for storing paper. Of the papers accommodated in the paper feed decks 301 and 302, only one of the topmost sheets is separated and conveyed to the transfer path 303. The developing stations 304 to 307 form a toner image using colored toners of Y, M, C, and K, respectively, in order to form a color image. The formed toner image is first transferred to the intermediate transfer belt 308, the intermediate transfer belt 308 rotates clockwise in the figure, and the toner image is transferred from the transfer path 303 at the secondary transfer position 309 at the process speed. Is transcribed. The display 225 displays information for the print status and settings of the image forming apparatus 101. The fixing unit 311 fixes the toner image on the paper. The fixing unit 311 includes a pressure roller and a heating roller, and the paper passes through a nip portion formed by the pressure roller and the heating roller to melt and crimp the toner and fix the toner image on the paper. The paper that has passed through the fixing unit 311 is conveyed to the transfer path 315 through the transfer path 312. When transporting a type of paper that needs to be further melted and crimped for fixing, such as thick paper with a large basis weight, the paper that has passed through the fixing unit 311 is transferred to the second fixing unit 313 using the upper transport path. Will be transported to. Then, the paper that has passed through the second fixing unit and has been additionally melted and crimped is conveyed to the transfer path 315 through the transfer path 314. When the image formation mode is double-sided, the paper is conveyed to the inversion path 316, inverted at 316, and then the paper is conveyed to the double-sided transfer path 317, and the image transfer of the second surface is performed at the secondary transfer position 309.

While the paper that has passed through the secondary transfer position 309 passes through the fixing unit 311 (or the second fixing unit 313), the paper is conveyed according to the process speed. The process speed is an example of the third transport speed, which is 464 mm / s in this embodiment. The printing apparatus 107 of the present embodiment has only a single process speed, but may have a configuration having a plurality of process speeds. Then, different process speeds may be set according to the paper attributes such as the basis weight, surface quality, and shape of the paper. However, even in that case, these plurality of process speeds are 750 mm or less, which is the first transport speed.

When transporting the paper in the transport path 315 to the outside of the printing apparatus 107, the paper transport speed is increased when the rear end of the paper passes through the fixing unit 311 (or the second fixing unit 313) to increase the speed of the paper and the paper. Widen the interval and secure the post-processing time of the post-processing equipment (not shown) connected downstream. In this embodiment, the paper transport speed is increased up to 1000 mm / s.

The paper that has passed through the printing device 107 is conveyed to the inspection device 108. CIS units 321 and 322 are arranged in the inspection device 108 so as to face each other. The CIS unit 321 reads an image formed on the upper surface of the paper. The CIS unit 322 reads an image formed on the lower surface of the paper. The inspection device 108 uses the CIS units 321 and 322 to read the image on the paper at the timing when the paper conveyed to the transfer path 323 reaches a predetermined position, and determines whether or not a printing defect has occurred. The display unit 236 displays the inspection results and the like performed by the inspection device 108. The CIS unit may be another optical system sensor such as a CCD or CMOS.

In this embodiment, the paper transport speed when reading an image by the CIS units 321 and 322 is 750 mm / s. That is, when the paper is conveyed through the transfer path 315 of the printing apparatus 107 for performing the inspection process, the transfer speed of the paper is changed from the process speed of 464 mm / s to 750 mm / s, which is an example of the first transfer speed. Increase the transport speed. Then, the printing device 107 is transported to the outside of the machine (downstream device, inspection device 108 in this embodiment). The timing for increasing the speed from the process speed to the first transport speed is after the rear end of the paper has passed through the fixing unit 311 or the second fixing unit 313 of the printing apparatus 107.

On the other hand, when the inspection device 108 does not perform the inspection process, that is, when the images are not read by the CIS units 321 and 322, the transport speed of the paper transported through the transport path 315 is 1000 mm /, which is an example of the second transport speed. s. That is, in this case, the paper transport speed is adjusted from the process speed of 464 mm / s to the second transport speed of 1000 mm after the rear edge of the paper has passed through the fixing unit 311 or the second fixing unit 313 of the printing apparatus 107. Speed up to / s. There is no difference in the throughput of discharging the paper between the case of transporting at 1000 mm / s and the case of transporting at 750 mm / s.

The large-capacity stacker 109 is a paper ejection device that is connected downstream of the inspection device 108 in the transport direction and ejects a large amount of printed paper. The large-capacity stacker 109 has a stack tray 331 as an example of a first discharge tray for loading paper. The paper that has passed through the inspection device 108 is conveyed to the large-capacity stacker 109 through the transfer path 332. The paper conveyed to the large-capacity stacker 109 is loaded on the stack tray 331 from the transfer path 332 via the transfer path 333. Further, the large capacity stacker 109 has an escape tray 334 as an example of the second discharge tray. The escape tray 334 is a paper ejection tray used for ejecting paper that is determined to be defective printing, that is, defective paper by the inspection device 108. When the defective paper is discharged to the escape tray 334, the paper received from the inspection device 108 is discharged from the transport path 332 to the escape tray 334 via the transport path 335. When the post-processing device (not shown) in the subsequent stage of the large-capacity stacker 109 executes post-processing such as bookbinding and binding processing, the paper received from the inspection device 108 is transported via the transport path 336. The reversing unit 337 is a mechanism for reversing the front and back sides of the paper. The reversing unit 337 is used when the printed paper is loaded on the stack tray 331. When loading on the stack tray 331, the front and back sides of the paper are once reversed by the reversing unit 337 so that the orientation of the received paper and the orientation of the paper at the time of output are the same. When the paper is transported to the escape tray 334 or the subsequent post-processing device, the paper is ejected as it is without flipping at the time of loading, so that the reversing operation at the reversing unit 337 is not performed.

[Instruction on whether or not to carry out inspection]
FIG. 4 is an example of a setting screen displayed on the display 225 of the printing device 107. FIG. 4A is a setting screen for performing default (standard) inspection settings set for the entire image forming apparatus 101. The inspection standard setting 401 is a setting item for setting whether or not to execute the inspection process by default (standard). When the button 403 in the inspection standard setting 401 is pressed (touched), the pull-down menu 402 is displayed. If the inspection process is not performed by default (standard), "No" (402a) is selected. On the contrary, when the inspection process is performed by default (standard), "Yes" (402b) is selected.

4 (b) and 4 (c) are setting screens for displaying a list of print jobs submitted from the client PC 103 in a list. The job list 411 in FIG. 4B and the job list 421 in FIG. 4C show a list of print jobs input from the client PC 103, respectively. Here, a situation in which three print jobs entitled Sample Jobs 1 to 3 are input to the image forming apparatus 101 is shown as an example.

The inspection 412 and the inspection 422 in the figure are check buttons for instructing each print job to carry out or not carry out the inspection process. When the check button is pressed, a check mark (check) is added to the corresponding print job, and when the check button is pressed again, the check mark (check) is removed and the mark returns to unmarked.

In this embodiment, the print job input from the client PC 103 does not start printing immediately after being received, but is started by selecting a print job from the job list 411 and 421 and pressing the start buttons 414 and 424. do.

The states 413 and 423 in the figure indicate the execution status of the print job, the print job that has already been started is displayed as "executing", and the job that has not yet started is displayed as "waiting".

When the inspection standard setting 401 is set to "No" on the screen of FIG. 4A, the inspection is not performed when the check button of the inspection 412 is not marked as shown in FIG. 4B. It is a setting, and the state where the check button is marked with a check mark is the setting for inspection.

In the example of FIG. 4B, the check buttons of sample jobs 1 and 3 are unmarked, and the check buttons of sample job 2 are marked with a check mark. That is, the sample jobs 1 and 3 do not perform the inspection, and the sample jobs 2 perform the inspection.

When the inspection standard setting 401 is set to "Yes" on the screen of FIG. 4A, the check button of the inspection 422 is not marked with a check mark as shown in FIG. 4C. It is set to inspect, and the state where the check button is marked with a check mark is the setting not to inspect.

In the example of FIG. 4C, the check buttons of the sample job 1 and the sample job 3 are unmarked, and the check buttons of the sample job 2 are marked with a check mark. That is, the sample job 1 and the sample job 3 perform the inspection process, and the sample job 2 does not perform the inspection process.

The relationship between the inspection standard setting 401 of FIG. 4 (a) and the state of the check buttons of inspections 421 and 422 shown in FIGS. 4 (b) and 4 (c) is shown in the table (table) as shown in FIG. 4 (d). ) Can be summarized.

In this embodiment, the table corresponding to FIG. 4D is stored in the memory 223 of the printing apparatus 107 as a part of the program. Then, based on the settings of the check buttons of the inspection standard setting 401 and the inspections 421 and 422, the execution / non-execution of the inspection process for each print job is determined.

Users who handle a relatively large number of print jobs that do not perform inspections can set the inspection standard setting 401 to "No", and users who handle a relatively large number of print jobs that perform inspections can set the inspection standard setting to "Yes". It is possible to reduce the trouble of setting the check button of the inspections 421 and 422.

It should be noted that, unlike the inspections 421 and 422 shown in FIGS. 4 (b) and 4 (c), the item for setting the execution / non-execution of the inspection process is not provided for each print job, and the entire inspection device 108 is covered. The configuration may be such that only the presence / absence of the inspection process is set. That is, the inspection standard setting 401 of FIG. 4A may be used to directly determine whether or not the inspection is to be performed, and the setting may be made when necessary.

[Reading performance of inspection equipment]
In this embodiment, the reading resolution of the inspection device 108 in the CIS units 321 and 322 is set to 400 dpi in order to detect fine print defects such as streaks and spots in the printed image formed on the paper.

The maximum transport speed when transporting the transport path 315 of the printing apparatus 107 is 1000 mm / s. On the other hand, due to the performance limitation of the line sensor, it is necessary to set the reading resolution to 750 mm / s in order to read the image at a reading resolution of 400 dpi.

This is because using a line sensor that can read at 1000 mm / s leads to an increase in cost, and cost performance is not good for users who handle both printed matter that requires inspection and printed matter that does not necessarily require inspection. be.

Therefore, in this embodiment, the print job without inspection is transported to the outside of the printing device 107 at 1000 mm / s, and the print job to be inspected is transported to the outside of the printing device 107 at 750 mm / s. , Suppress the cost increase of the line sensor.

[Switching of transport speed]
The image forming apparatus 101 can start the next print job while the print job is being executed. In this case, printing of the next print job is started as soon as the previous print job is completed.

When switching from a print job to a job to be inspected from a job not to be inspected, the transfer speed is changed from 1000 mm / s to 750 mm / s. On the contrary, when switching from the job to be inspected to the job not to be inspected, the transport speed is changed from 750 mm / s to 1000 mm / s.

It usually takes a certain amount of time to change the transport speed, that is, to change the rotation speed of the motor. Further, when switching from a job with a slow transfer speed to a job with a high transfer speed, it is necessary to prevent the paper of the later job from catching up with the paper of the previous job and colliding with each other.

Therefore, in this embodiment, when the job to be inspected is switched to the job not to be inspected, the printing apparatus 107 is spaced by a predetermined time.

Specifically, as shown in FIG. 14, the paper of the next job having a high transport speed is prevented from colliding with the paper of the next job having a high transport speed by the time the paper of the previous job having a slow transport speed is ejected to the output tray.

The horizontal axis of the graph of FIG. 14 represents time, and the vertical axis represents position on the transport path. The straight line A shows how the rear end of the paper conveyed at the speed V1 (750 mm / s) moves toward the output tray 331 with the passage of time. The straight line C shows how the tip of the paper transported at the transport speed V2 (1000 mm / s) moves toward the output tray 331 with the passage of time. In order to prevent the paper having the transport speed V2 from colliding with the paper having the transport speed V1, the straight line C may be located on the right side of the graph from the line shown by the alternate long and short dash line B in the drawing. That is, the interval may be opened by the time Ta represented by the following equation 1.

Ta ≧ La / V1-La / V2 ... (Equation 1)
In this embodiment, the time required to change the rotation speed of the motor is not considered because it is sufficiently small with respect to the paper transport interval, but if necessary, such time may be taken into consideration to allow an interval.

[Printing device control flow]
FIG. 5 is a flowchart showing a printing operation of the printing device 107. Each process shown in the flowchart of FIG. 5 is executed by the CPU 222 of the printing apparatus 107. Further, the printing device 107 receives information about the printing job such as an inspection necessity instruction, a printing job ID, and a paper size from the external controller 102 via the internal LAN 105.

First, in step S501, the CPU 222 determines the paper transfer speed in the reading units 321 and 222 of the inspection device 108, and in the next step S502, the printing process is performed. The processing of S501 will be described in detail with reference to FIG. 6, and the processing of S502 will be described in detail with reference to FIG.

The process shown in FIG. 5 is executed for each page constituting the print job. When the processing shown in FIG. 5 is completed for all the pages, the processing of the flowchart of FIG. 5 is completed.

[Determination of transport speed in the reading unit]
FIG. 6 is a process of determining the transport speed in the reading units 321 and 322, and shows the details of step S501 in FIG.

First, in step S601, the CPU 222 confirms whether or not the inspection process set is performed via the setting screen of FIG. If step S601 is true, that is, if it is set to perform the inspection process on the print job, the transfer speed V in the reading units 321 and 322 is determined to be V1 in the next step S602. V1 is an example of the first transport speed, and in this embodiment, V1 is 750 mm / s.

If step S602 is false, that is, if it is set not to perform the inspection process on the print job, the transfer speed V in the reading units 321 and 322 is determined to be V2 in the next step S603. V2 is an example of the second transfer speed, and a value higher than V1 which is at least the first transfer speed is set. In this embodiment, V2 is 1000 mm / s.

[Printing process of printing device]
FIG. 7 shows the details of step S502 of FIG. First, in step S701, the CPU 222 determines whether or not the paper transfer speed V of the page of interest is different from the paper transfer speed of the immediately preceding page. If step S701 is true, the transfer speed is switched. Therefore, in the next step S702, the distance from the previous paper is increased by a predetermined time.

Here, the predetermined time is the time Ta shown in (Equation 1) when the transfer speed is changed from V1 (750 mm / s) to the transfer speed V2 (conveyed at 1000 mm / s), and V2 to V1. It is 0 when switching to. If step S701 is false, the process proceeds to the next step.

In the next step S703, an image is formed on paper. The process speed (third transport speed) at this time is 452 mm / s. Then, in step S704, the transport speed after the rear end of the paper has passed through the fixing unit 311 (or the second fixing unit 313) is set to V, and the paper is discharged to the inspection device 108.

[Control flow of inspection equipment]
As the external controller 102 receives the print job from the client PC 103 and the printing device 107 starts printing, the inspection device 108 also starts the inspection process.

FIG. 8 shows an inspection operation performed by the inspection device 108 based on a print job. This process is executed by the CPU 233 of the inspection device 108. Further, information about the print job, such as an instruction as to whether or not inspection is necessary, a print job ID, and a paper size, is transmitted from the external controller 102 to the inspection device 108 via the internal LAN 105 and the communication cable 249.

First, in step S801, the transfer speed of the paper to be conveyed by the reading units 321 and 322 of the inspection device 108 is determined, and in the next step S802, the inspection process is performed. The details of step S801 are the same as the process shown in FIG. In this embodiment, the same flowchart is individually executed by the CPU 222 of the printing device 107 and the CPU 233 of the inspection device 108. Another method, for example, the transfer speed V determined by the CPU 222 of the printing device 107 is notified to the CPU 233 of the inspection device 108 via the communication cable 249, and the inspection device 108 uses the notified transfer speed. The configuration may be different.

The process shown in FIG. 8 is executed for all the pages constituting the print job. When the processing shown in FIG. 8 for all the pages is completed, the inspection device 108 is stopped.

[Inspection processing of inspection equipment]
FIG. 9 is a flowchart showing the inspection process in the inspection device 108, and shows the details of step S802 of FIG. In step S901, it is determined whether or not the paper transport speed V of the page of interest is different from the paper transport speed of the immediately preceding page. If step S901 is true, the transfer speed is switched, so that the next step S902 waits for a predetermined time.

Here, the predetermined time is the time Ta shown in (Equation 1) when the transfer speed is changed from V1 (750 mm / s) to the transfer speed V2 (transport at 1000 mm / s), and the transfer speed is V2. It is 0 when the transfer speed is switched to V1. If step S901 is false, the process proceeds to the next step.

In step S903, the inspection device 108 pulls the paper from the printing device 107 at a transport speed V. The transport speed of the paper drawn from the printing device 107 here means the paper transport speed when transporting the transport path 323 in the inspection device 108. In this embodiment, the transport speed of the paper conveyed through the transport path 323 is the same as the transport speed of the paper conveyed through the transport path 315 of the printing apparatus 107.

In the next step S904, it is confirmed whether or not the inspection process is performed. If step S904 is true, that is, if an inspection is to be performed, the inspection process is executed in the next step S905. Specifically, the CIS units 321 and 322 read the image on the paper conveyed at the first transfer speed at a predetermined reading resolution (400 dpi). Then, the image data obtained by reading is analyzed by the CPU 233 that functions as an inspection means, and the presence or absence of printing defects is inspected. For example, inspection processing such as comparison between the image data obtained by reading and the reference image, calculation of the amount of print position deviation, and detection of color shift, streaks, spots, etc. is executed. If step S904 is false, the process proceeds to the next step without performing the inspection process. In step S906, the paper ejection operation is executed. The inspection device 108 determines the paper ejection destination according to whether or not the inspection process is performed and the result of the inspection process. Specifically, when the inspection process is set to be performed and the paper is not determined to be printing defective in the inspection process, the stack tray 331, which is the first discharge tray, is determined as the discharge destination. Further, when the inspection process is set to be performed and the paper is determined to be poorly printed in the inspection process, the escape tray 334, which is the second discharge tray, is determined as the discharge destination. When it is set not to carry out the inspection process, the inspection device 109 is transported to a post-processing device (not shown) connected downstream in the transport direction at a second transport speed via the transport path 336. The paper is delivered and discharged to a third discharge tray provided in the aftertreatment device. When the aftertreatment device is not connected downstream of the inspection device 109, the printed matter that is not inspected may be discharged to the first discharge tray or the second discharge tray.

The first embodiment has been described above. According to this embodiment, for the print job that performs the inspection process, the paper transfer speed after passing through the fixing unit 311 in the printing apparatus 107 is set to the first transfer speed. As a result, for the print job that performs the inspection process, the paper transport speed is set to be relatively low, so that the amount of image data read by the reading unit per unit time can be suppressed. Therefore, even a CPU having a low processing capacity can execute the inspection process. Further, by reducing the paper transport speed, high-resolution image data can be obtained, minute streaks and spots can be detected, and inspection accuracy can be improved.

Further, according to the present embodiment, on the other hand, for the print job in which the inspection process is not performed, the paper transfer speed after passing through the fixing unit 311 is set to the second transfer speed higher than the first transfer speed. As a result, the throughput can be improved. In particular, when performing post-processing with a post-processing device connected downstream in the transport direction of the inspection device, the space between papers can be widened by transporting at a transport speed faster than the process speed. Post-processing time can be secured.

[Restrictions on post-processing equipment]
Next, Example 2 will be described. In the second embodiment, each roller for transporting paper arranged on the transport path of the large-capacity stacker 109 is driven by the same drive source (motor (not shown)). In such a case, the transport speed cannot be switched until all the paper in the machine is ejected.

That is, as shown in FIG. 15, when switching from the print job to be inspected to the print job not to be inspected, the transfer speed can be switched with all the paper in the large-capacity stacker 109 ejected. It is necessary to leave a transport interval. Similarly, when switching from a job that does not perform inspection to a print job that performs inspection, it is necessary to leave a paper transfer interval as shown in FIG.

The horizontal axis of the graph of FIG. 15 represents time, and the vertical axis represents position on the transport path. The straight line A in FIG. 15A shows how the rear end of the paper conveyed at the speed V1 (750 mm / s) moves toward the output tray 331 with the passage of time. The straight line C shows how the tip of the paper transported at the transport speed V2 (1000 mm / s) moves toward the output tray 331 with the passage of time.

In order to transport the paper having the transport speed V2 after all the paper having the transport speed V1 in the large-capacity stacker 109 is ejected, the straight line C may be located on the right side of the graph from the alternate long and short dash line B in the figure. .. That is, the interval is set by the time Tb represented by the following equation 2.

Tb ≧ Lb / V1 ... (Equation 2)
Similarly, the straight line A in FIG. 15B shows how the rear end of the paper being conveyed at a speed V2 (1000 mm / s) moves toward the output tray 331 with the passage of time. The straight line C shows how the tip of the paper transported at the transport speed V1 (750 mm / s) moves toward the output tray 331 with the passage of time.

In order for the paper having the transport speed V1 to be transported after all the paper having the transport speed V2 in the large-capacity stacker 109 has been ejected, an interval of time Tc represented by the following formula 3 is required.

Tc ≧ Lb / V2 ... (Equation 3)
Therefore, the throughput decreases every time the print job to be inspected and the print job not to be inspected are switched. For example, as shown in FIG. 16, when a print job of a small number of pages not to be inspected is sent between print jobs to be inspected, the paper interval is twice in a short period of time (Tb and Tc in the figure). ) It will be vacant. Therefore, it tends to lead to a decrease in throughput. In FIG. 16, the widths of the paper with inspection and the paper without inspection are different. This is because the horizontal axis in the figure represents time, and even if the length of the paper is the same, the transport speed of the paper without inspection is high, and it becomes shorter when converted to time.

In order to avoid such a decrease in throughput, in this embodiment, in order to prevent fine speed switching from occurring, when a print job that performs inspection processing is switched to a print job that does not perform inspection processing, The transport speed is not switched.

When switching from a print job that does not perform inspection to a print job that performs inspection, the transport speed is switched and inspection is performed.

[Printing device control flow]
When the external controller 102 receives the print job from the client PC 103, the printing device 107 starts printing. FIG. 10 shows the printing operation performed by the printing apparatus 107 in the second embodiment. The processing of the flowchart of FIG. 10 is executed by the CPU 222 of the printing device 107. Further, information about the print job such as an instruction of inspection necessity, a print job ID, and a paper size is transmitted from the external controller 102 to the printing device 107 via the internal LAN 105.

First, in step S1001, the reading units 321 and 322 of the inspection device 108 perform a process of determining whether or not it is necessary to change the paper transport speed when the job is switched. In step S1002, the determination result in step S1001 is confirmed. If it is determined that step S1002 is true, that is, the transfer speed is changed, the transfer speed is determined in the next step S1003. If it is determined that step S1002 is false, that is, the transfer speed is not changed, the process proceeds to the next step. In step S1004, a printing process is performed. The details of the printing process in step S1004 are as described with reference to FIG. 7, but the paper spacing to be widened in step S702 is different. In the second embodiment, when the transfer speed is changed from V1 (750 mm / s) to the transfer speed V2 (conveyed at 1000 mm / s), the time Tb shown in (Equation 2) is used. On the contrary, in the case of switching from V2 to V1, it is the time Tc shown in (Equation 3).

The process shown in FIG. 10 is executed for each page constituting the print job. When the processing shown in FIG. 10 for all the pages is completed, the printing apparatus 107 is stopped.

[Judgment of print job switching]
FIG. 11 is a flowchart showing a process of determining whether or not it is necessary to change the paper transport speed in the reading units 321 and 322 of the inspection device 108 when the print job is switched, and shows the details of step S1001 of FIG. ..

First, in step S1101, it is determined whether or not the print job being processed is the first page of the first job. Here, the head job refers to a job submitted when the printing device 107 is in the standby state.

If step S1101 is true, that is, if it is the first page of a print job submitted when the printing apparatus 107 is in the standby state, it is determined that the speed change is "performed".

If step S1101 is false, in the next step S1102, it is confirmed whether or not it is the first page of the next job. Here, the next job refers to a print job newly submitted while the printing device 107 is already performing the printing operation.

If step S1102 is false, it is determined in the next step S1108 that the speed change is not performed, and the already set transfer speed is maintained.

If step S1102 is true, that is, if the print job is switched to the next print job, it is confirmed in the next step S1103 whether the preceding print job is inspected and the subsequent next print job is not inspected. do.

If step S1103 is true, it is determined in the next step S1106 that the speed change is "not". As a result, the transport speed V is maintained at V1 instead of becoming V2.

If step S1103 is false, in the next step S1104, it is confirmed whether or not the previous job is not inspected and the next job is inspected.

If step S1104 is true, it is determined that the speed change is "performed" in order to set the transport speed to V1 for reading by the inspection device 108.

If step S1104 is false, it is determined in the next step S1108 that the speed change is not performed, and the already set transfer speed is maintained.

[Determination of transport speed in the reading unit]
FIG. 12 is a process of determining the transport speed in the reading units 321 and 322, and shows the details of step S1003 of FIG. First, in step S1201, it is confirmed whether or not the inspection process set by the setting screen of FIG. 4 is performed. If step S1201 is true, that is, if it is set to perform the inspection process on the print job, the transfer speed V in the reading units 321 and 322 is determined to be V1 in the next step S1202.

If step S1202 is false, that is, if it is instructed not to inspect the print job, the transfer speed V in the reading units 321 and 322 is determined to be V2 in the next step S1203. In this embodiment, V1 is 750 mm / s and V2 is 1000 mm / s.

[Control flow of inspection equipment]
As the external controller 102 receives the print job from the client PC 103 and the printing device 107 starts printing, the inspection device 108 also starts the inspection process.

FIG. 13 shows an inspection operation performed by the inspection device 108 based on the print job in the second embodiment. This process is executed by the CPU 233 of the inspection device 108.

Further, information about the print job such as an instruction of inspection necessity, a print job ID, and a paper size is transmitted from the external controller 102 to the printing device 107 via the internal LAN 105 and the communication cable 249.

First, in step S1301, it is determined whether or not it is necessary to set the paper transport speed in the reading units 321 and 322 of the inspection device 108 when the print job is switched.

In step S1302, the determination result in step S1301 is confirmed. If it is determined that step S1302 is true, that is, the transfer speed is set, the transfer speed is determined in the next step S1303.

If it is determined that step S1302 is false, that is, the transfer speed is not set, the process proceeds to the next step S1304, and the inspection process is performed.

The details of steps S1301 and S1303 are the same as the flows shown in FIGS. 11 and 12, respectively. In this embodiment, the same flow is individually executed by the CPU 222 of the printing device 107 and the CPU 233 of the inspection device 108.

Another method, for example, the transfer speed V determined by the CPU 222 of the printing device 107 is notified to the CPU 233 of the communication cable 249 inspection device 108, and the inspection device 108 uses the notified transfer speed. You may.

The details of the printing process in step S1304 are as described with reference to FIG. 9, but the waiting time in step S902 is different. In the second embodiment, when the transfer speed is changed from V1 (750 mm / s) to the transfer speed V2 (conveyed at 1000 mm / s), the time Tb shown in (Equation 2) is used. On the contrary, in the case of switching from V2 to V1, it is the time Tc shown in (Equation 3).

The process shown in FIG. 13 is executed for each page constituting the print job. When the processing shown in FIG. 13 for all the pages is completed, the inspection device 108 is stopped.

[Switching from a print job that is inspected to a print job that is not inspected]
FIG. 17 shows a state when the print job to be inspected and the print job not to be inspected are switched in the second embodiment. FIG. 17 (a) is an operation of a comparative example, and FIG. 17 (b) is an operation according to the second embodiment.

In the second embodiment, when switching from the print job of "with inspection" to the print job of "without inspection", the paper is continuously passed without changing the transport speed. As a result, the total printing time is shortened as shown by X in the figure because the papers are not spaced apart.

The second embodiment has been described above. According to this embodiment, when a print job that performs inspection processing and a print job that does not perform inspection processing are executed in succession, an example in which a print job that does not perform inspection processing is also conveyed at the first transfer speed. Was explained. As a result, the entire printing time can be shortened.

<Modification example>
In the above-described embodiment, an example in which the control unit in the inspection device 108 executes the inspection process has been described. However, the printing device 107 may execute the inspection process. The form may be performed by the external controller 102. In that case, the communication I / F 232 transmits the image data obtained by reading the image by the CIS units 321 and 322 to the printing device 107 via the communication cable 249. Then, the CPU 222 of the printing device 107 that has received the image data compares the received image data with the reference image registered in advance, and executes the inspection process.

Further, the inspection process may be executed by the external controller 102. In that case, the communication I / F 232 that functions as the transmission means transmits to the external controller 102 via the communication cable 249 or the internal LAN 105. The external controller 102 that has received the image data compares the received image data with the reference image registered in advance, and executes the inspection process. Similarly, the inspection process may be executed by an external device connected to the external LAN 104.

Further, in the image forming apparatus 101 according to the above-described embodiment, the printing apparatus 107 and the inspection apparatus 108 are directly connected to each other. However, even in a configuration in which another optional device or the like is interposed between the printing device 107 and the inspection device 108. For example, an optional device such as a cooling device for cooling the paper, an inserter device for inserting the preprinted paper, and a punching device for punching the paper may be interposed between the printing device 107 and the inspection device 108. .. When the optional device is arranged between the printing device 107 and the inspection device 108 in this way, the paper transport speed when the paper is delivered between the printing device 107 and the optional device is determined by whether or not the inspection process is performed. It is preferable to make them different according to the situation.

(Other Examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

101 Image forming device 102 External controller 103 Client PC
104 External LAN
105 Internal LAN
106 Video cable 107 Printing device 108 Inspection device 109 Large capacity stacker 208 CPU
209 Memory 212 Display 214 LANI / F
215 Video I / F
217 Communication I / F
218 LAI / F
220 Video I / F
222 CPU
223 memory 232 communication I / F
233 CPU
234 Memory 235 Image reader 236 Display unit 237 Operation unit 250 Image processing unit 321 CIS unit 322 CIS unit 236 Display unit 331 Stack tray 334 Escape tray

Claims (10)

A printing method for printing images on paper,
A transport means for transporting paper on which an image is printed by the printing means along a transport path, and a transport means.
A reading means that is arranged downstream of the printing means in the paper conveying direction and reads an image on the paper conveyed from the printing means at a predetermined reading resolution.
An inspection means that performs an inspection process for inspecting the presence or absence of printing defects based on the image data obtained by reading an image by the reading means, and an inspection means.
The transport speed of the paper in the print job that does not perform the inspection process when the paper is transported along the transport path is higher than the transport speed of the paper in the print job that performs the inspection process. , The control means for controlling the transport means, and
An image forming apparatus characterized by having. It has a setting means for setting whether or not to perform the inspection process in the inspection means.
The control means
When the setting means is set to perform the inspection process, the paper is conveyed at the first transfer speed, and when the setting means is set not to perform the inspection process, the first transfer speed is increased. The image forming apparatus according to claim 1, wherein the transporting means is controlled so as to transport the paper at a high second transport speed. The image forming apparatus according to claim 2, wherein the setting means sets whether or not to perform the inspection process for a print job. The printing means
It has a transfer means to transfer the image to the paper transported at the process speed.
The image forming apparatus according to claim 2, wherein the first transport speed and the second transport speed are higher than the process speed. The image forming apparatus according to any one of claims 1 to 4, wherein the reading means is provided in the transport path. A plurality of ejection trays from which the paper that has been subjected to the inspection process and has not been determined to be printing defective, the paper that has been subjected to the inspection process and has been determined to be printing defective, and the paper that has not been subjected to the inspection process are ejected. The image forming apparatus according to any one of claims 1 to 5, further comprising a paper ejection means provided. The plurality of discharge trays
The first discharge tray from which the paper that has been inspected and is not determined to be defective in printing is discharged,
A second discharge tray from which paper that has been subjected to the above inspection process and is determined to be printing defective is discharged,
A third discharge tray from which paper that has not been inspected is discharged, and
The image forming apparatus according to claim 6, wherein the image forming apparatus comprises. The image forming apparatus according to any one of claims 1 to 7, further comprising a display unit for displaying an inspection result in the inspection process. When the control means continuously processes a preceding print job that performs the inspection process and a subsequent print job that does not perform the inspection process, the control means does not switch the transfer speed, and the preceding print job and the subsequent print job. The image forming apparatus according to claim 2, wherein the transfer means is controlled so as to transfer the paper at the first transfer speed for any of the print jobs to be performed. An image forming device capable of communicating with an inspection device.
A printing method for printing images on paper,
A transport means for transporting paper on which an image is printed by the printing means along a transport path, and a transport means.
A reading means that is arranged downstream of the printing means in the paper conveying direction and reads an image on the paper conveyed from the printing means at a predetermined reading resolution.
A transmission means for transmitting the image data to the inspection device in order to execute an inspection process for inspecting the presence or absence of printing defects based on the image data obtained by reading the image by the reading means.
The transport speed of the paper in the print job that does not perform the inspection process when the paper is transported along the transport path is higher than the transport speed of the paper in the print job that performs the inspection process. , The control means for controlling the transport means, and
An image forming apparatus characterized by having.

Images