Image forming apparatus

Abstract

To provide line sensors common between a plurality of models for use in determination of quality of an output image.SOLUTION: A plurality of line sensors 3 is arranged along a width direction intersecting a sheet conveyance direction and the line sensors partially overlap each other at positions in the width direction, and read images of a plurality of partial areas each including a non-superimposed area not overlapping an adjacent area and a superimposed area overlapping the adjacent area, each of which is a part of a sheet passage area in the width direction. An image determination unit 8c determines whether a pieces of data of a plurality of read images obtained from the plurality of line sensors 3 satisfy permission conditions based on a plurality of pieces of reference image data. An error processing unit 8d executes predetermined error processing when any one of the pieces of data of the plurality of read images is determined not to satisfy the permission conditions.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus capable of determining the quality of an image formed on a sheet. [Background technology]

[0002] An image forming apparatus includes a printing device that forms an image on a sheet. It is known that the image forming apparatus reads the output image formed on the sheet and determines whether or not there is an abnormality in the output image based on the read image (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-78366 A Summary of the Invention [Problem to be solved by the invention]

[0004] The output image formed on the sheet is read by a line sensor. Generally, the line sensor has a length corresponding to the maximum width of the sheet that can be used.

[0005] When line sensors of different lengths are used for different models with different maximum sheet widths, it is necessary to manage many types of line sensors. On the other hand, it is desirable to be able to standardize parts among a plurality of models.

[0006] An object of the present invention is to provide an image forming apparatus in which a line sensor used for determining the quality of an output image can be standardized among a plurality of models. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus includes a printing device, a plurality of line sensors, an image determination unit, and an error processing unit. The printing device forms an image on a sheet transported along a transport path. The plurality of line sensors are arranged downstream of the printing device in a sheet transport direction, along a width direction intersecting the sheet transport direction, with the respective line sensors partially overlapping each other in the width direction, and read images of a plurality of partial areas from the sheet, each of which includes a non-overlapping area that is a part of a sheet passing area in the width direction and does not overlap with an adjacent area, and an overlapping area that overlaps with an adjacent area. The image determination unit determines whether data of each of a plurality of read images obtained by the plurality of line sensors satisfies or does not satisfy an allowable condition based on a plurality of reference image data representing images of the plurality of partial areas. The error processing unit executes a predetermined error process when it is determined that any of the data of the plurality of read images does not satisfy the allowable condition. Effect of the Invention

[0008] According to the present invention, it is possible to provide an image forming apparatus in which a line sensor used for determining the quality of an output image can be standardized among a plurality of models. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a control device in the image forming apparatus according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of an arrangement state of a plurality of line sensors in the image forming apparatus according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of a procedure of an image inspection process in the image forming apparatus according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing an example of a procedure of a first error process which is a part of an image inspection process in the image forming apparatus according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a procedure of a second error process which is a part of the image inspection process in the image forming apparatus according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing an example of an arrangement state of a plurality of line sensors in an image forming apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0011] [First embodiment: configuration of image forming apparatus 10] The image forming apparatus 10 according to the first embodiment includes a sheet storage unit 1, a sheet conveying device 2, and a printing device 5 (see FIG. 1).

[0012] The image forming apparatus 10 further includes a human interface device 800 and a control device 8. The control device 8 controls the sheet transport device 2 and the printing device 5.

[0013] The sheet conveying device 2 sends out the sheets 9 accommodated in the sheet accommodating unit 1 one by one to the conveying path 200. The sheet conveying device 2 further conveys the sheets 9 along the conveying path 200.

[0014] In this embodiment, the sheet conveying device 2 includes a primary conveying device 21, a belt conveying device 22, and a secondary conveying device .

[0015] The primary transport device 21 includes a sheet feeding mechanism 211 and a plurality of primary transport roller pairs 212 .

[0016] The sheet feeding mechanism 211 feeds the sheet 9 from the sheet storage unit 1 to the conveying path 200. The primary conveying roller pair 212 conveys the sheet 9 along the conveying path 200, and further sends the sheet 9 to the belt conveying device 22.

[0017] The belt conveying device 22 takes over the conveyance of the sheet 9 from the primary conveying device 21. The belt conveying device 22 conveys the sheet 9 along the conveying path 200, and further sends the sheet 9 to the secondary conveying device 23.

[0018] The belt conveying device 22 includes a conveying belt 221 and a plurality of support rollers 32. The belt conveying device 22 further includes a motor (not shown) that rotates one of the plurality of support rollers 32.

[0019] The conveyor belt 221 is an endless belt member. The conveyor belt 221 is rotatably supported by a plurality of support rollers 32. When one of the plurality of support rollers 32 rotates, the conveyor belt 221 rotates.

[0020] The belt conveying device 22 conveys the sheet 9, which has been sent out onto the conveying belt 221 by the primary conveying device 21, along the upper surface of the conveying belt 221. The belt conveying device 22 sends out the sheet 9 from the upper surface of the conveying belt 221 to the secondary conveying device 23. The area along the upper surface of the conveying belt 221 is a part of the conveying path 200.

[0021] The secondary conveying device 23 takes over the conveying of the sheet 9 from the belt conveying device 22. The secondary conveying device 23 conveys the sheet 9 along the conveying path 200, and further sends the sheet 9 from the conveying path 200 to a downstream part (not shown). For example, the downstream part is a discharge tray, a post-processing device, an intermediate conveying device, or the like.

[0022] The printing device 5 executes a printing process. The printing process is a process of forming an image on a sheet 9 conveyed along a conveying path 200.

[0023] In this embodiment, the printing device 5 forms an image on the sheet 9 conveyed by the belt conveying device 22. In the example shown in Fig. 1, the printing device 5 executes the printing process by an inkjet method.

[0024] In the example shown in FIG. 1, the printing device 5 includes a plurality of inkjet units 51 corresponding to a plurality of colors, and a plurality of ink supply units 52.

[0025] The ink supply units 52 each supply ink of a different color to the inkjet units 51. The inkjet units 51 form an image on the sheet 9 by ejecting ink onto the sheet 9.

[0026] The printing device 5 may be a device that executes the printing process using a method other than the inkjet method, such as an electrophotographic method.

[0027] [Human interface device 800] The human interface device 800 includes an operation device 801 and a display device 802 .

[0028] The operation device 801 is a device that detects operations by a person. For example, the operation device 801 includes one or both of a touch panel and operation buttons.

[0029] The display device 802 is a device that displays various types of information. For example, the display device 802 is a panel display device such as a liquid crystal display panel.

[0030] [Control device 8] The control device 8 includes a central processing unit (CPU) 81, a random access memory (RAM) 82, a secondary storage device 83, a signal interface 84, a communication device 85, and the like.

[0031] The secondary storage device 83 is a computer-readable non-volatile storage device. The secondary storage device 83 can store and update computer programs and various data. For example, one or both of a flash memory and a hard disk drive are adopted as the secondary storage device 83.

[0032] The signal interface 84 converts signals output by various sensors into digital data, and transmits the converted digital data to the CPU 81. Furthermore, the signal interface 84 converts control commands output by the CPU 81 into control signals, and transmits the control signals to the devices to be controlled.

[0033] The communication device 85 executes communication with other devices such as the host device 7. The CPU 81 communicates with the other devices through the communication device 85. The host device 7 is an information processing device such as a personal computer.

[0034] The host device 7 includes a human interface device 70 including an operation unit 71 and a display unit 72 (see FIG. 2). For example, the operation unit 71 includes one or more of a touch panel, a keyboard, and a mouse. The display unit 72 is a liquid crystal display or the like.

[0035] The CPU 81 is a processor that executes the computer program to perform various data processing and control operations. The control device 8 including the CPU 81 controls the sheet transport device 2, the printing device 5, and the like.

[0036] The RAM 82 is a computer-readable volatile storage device that temporarily stores the computer programs executed by the CPU 81 and data output and referenced by the CPU 81 in the course of executing various processes.

[0037] The CPU 81 includes a plurality of processing modules that are realized by executing the computer programs, and the plurality of processing modules include a main processing unit 8a and a print control unit 8b.

[0038] The main processing unit 8a executes processes to start various processes in response to the occurrence of various processing events, such as an operation event and a reception event.

[0039] The operation event is an event that various processing request operations are detected by the operation device 801. The reception event is an event that various processing request commands are received through the communication device 85. The processing request includes a print request for requesting execution of the print process.

[0040] The print control unit 8b controls the sheet transporting device 2 and the printing device 5. The print control unit 8b controls the sheet transporting device 2 to thereby control the transport of the sheet 9.

[0041] Furthermore, the print control unit 8b causes the printing device 5 to execute the print process in synchronization with the conveyance of the sheet 9 by the sheet conveying device 2.

[0042] For example, when the print request is received by the communication device 85, the print control section 8b causes the sheet conveying device 2 to convey the sheet 9 and causes the printing device 5 to execute the print process.

[0043] The image forming apparatus 10 is capable of executing an image inspection process, which will be described later. The image inspection process is a process for reading an output image formed on a sheet 9 and judging the presence or absence of an abnormality in the output image based on the read image.

[0044] The output image formed on the sheet 9 is read by a line sensor. In general, the line sensor has a length corresponding to the maximum width of the sheet 9 that can be used.

[0045] When line sensors of different lengths are used for different models of seat 9 with different maximum widths, it is necessary to manage many types of line sensors. On the other hand, it is desirable to be able to standardize parts among a plurality of models.

[0046] The image forming apparatus 10 has a configuration suitable for standardizing the line sensor used to determine the quality of an output image among a plurality of models. The configuration will be described below.

[0047] In the following description, the direction in which the sheet 9 is conveyed along the conveying path 200 is referred to as a sheet conveying direction D1 (see FIGS. 1 and 3). Also, the direction intersecting the sheet conveying direction D1 is referred to as a width direction D2 (see FIGS. 1 and 3).

[0048] The width direction D2 corresponds to the main scanning direction in the printing device 5. Moreover, the sheet transport direction D1 is a direction along the sub-scanning direction in the printing device 5. In this embodiment, the width direction D2 is a direction perpendicular to the sheet transport direction D1.

[0049] The image forming apparatus 10 further includes a plurality of line sensors 3 (see FIGS. 1 and 3). The plurality of line sensors 3 are disposed downstream in the sheet conveying direction D1 with respect to the printing device 5. For example, each of the line sensors 3 is a CIS (Contact Image Sensor).

[0050] In this embodiment, the multiple line sensors 3 are disposed facing an area between the belt conveying device 22 and the secondary conveying device 23 in the conveying path 200 (see FIG. 1). The multiple line sensors 3 are disposed at two positions offset from each other in the sheet conveying direction D1.

[0051] The multiple line sensors 3 are arranged along the width direction D2 with their positions in the width direction D2 partially overlapping each other (see FIG. 3). The multiple line sensors 3 read images of multiple partial areas A1, which are each part of the sheet passing area in the width direction D2, from the sheet 9 (see FIG. 3). The sheet passing area is an area that corresponds to the maximum width of the sheet 9 that can be used.

[0052] Each of the partial regions A1 includes a non-overlapping region A2 and an overlapping region A3. The non-overlapping region A2 is a region that does not overlap with an adjacent region in the partial regions A1. On the other hand, the overlapping region A3 is a region that overlaps with an adjacent region in the partial regions A1.

[0053] The image forming apparatus 10 further includes a plurality of white reference members 4 (see FIGS. 1 and 3) disposed opposite the plurality of line sensors 3. Each of the white reference members 4 has a white surface.

[0054] The plurality of line sensors 3 output data of a white image by executing a process of reading an image when the sheet 9 is not being conveyed. The white image is an image representing the surfaces of the plurality of white reference members 4.

[0055] The white image data is used in a sensitivity adjustment process for adjusting the sensitivity of each line sensor 3. A description of the sensitivity adjustment process will be omitted.

[0056] In this embodiment, the image forming apparatus 10 includes two rotatably supported roller-shaped white reference members 4. The two white reference members 4 are disposed at positions facing two locations in the sheet conveying direction D1 where the multiple line sensors 3 are disposed (see FIGS. 1 and 3).

[0057] Since the two white reference members 4 are roller-shaped, the sheet 9 is smoothly transported along the circumferential surfaces of the two white reference members 4.

[0058] In this embodiment, the image forming apparatus 10 includes two line sensors 3. In this case, the sheet passing area is divided into two non-overlapping areas A2 and one overlapping area A3. One of the two non-overlapping areas A2 and the overlapping area A3 is one of two partial areas A1. The other of the two non-overlapping areas A2 and the overlapping area A3 is the other of the two partial areas A1.

[0059] The plurality of processing modules of the CPU 81 further includes an image determination unit 8c and an error processing unit 8d (see FIG. 2).

[0060] The image determination unit 8c executes image quality determination processing based on data of each of a plurality of read images obtained by a plurality of line sensors 3. The image quality determination processing is processing for determining whether or not data of each of the plurality of read images satisfies an allowable condition based on each of a plurality of reference image data.

[0061] The plurality of reference image data are data representing images of the plurality of partial regions A1 in the image formed on the sheet 9. Each of the plurality of reference image data is data representing an image to be formed in each of the plurality of partial regions A1 on the sheet 9.

[0062] An error processing unit 8d executes a predetermined error process when it is determined that any of the data of the plurality of read images does not satisfy the permissible condition.

[0063] [Image inspection processing] An example of the procedure of the image inspection process will be described below with reference to the flowchart shown in Fig. 4. The image inspection process is executed by the print control unit 8b, the image determination unit 8c, and the error processing unit 8d.

[0064] For example, the print control unit 8b starts the image inspection process every time the print process is executed on a preset reference number of sheets 9.

[0065] In addition, the print control unit 8b may start the image inspection process when an inspection request is input via the operation device 801 or the communication device 85.

[0066] In the following description, S101, S102, ... represent identification codes of a plurality of steps in the image inspection process. In the image inspection process, the process of step S101 is executed first.

[0067] <Process S101> In step S101, the print control unit 8b causes the sheet conveying device 2 and the printing device 5 to execute a test print process for forming a test image G1 on a sheet 9 (see FIG. 3).

[0068] The test image G1 is a predetermined pattern image. The test image G1 is formed across all of the non-overlapping area A2 and the overlapping area A3 on the sheet 9 (see FIG. 3). The test image G1 is an example of an output image formed on the sheet 9.

[0069] The sheet conveying device 2 passes the sheet 9 on which the test image G1 is formed through an area facing the multiple line sensors 3.

[0070] After executing the process of step S101, the print control unit 8b shifts the process to step S102.

[0071] <Process S102> In step S102, when the sheet 9 passes through an area facing the line sensors 3, the image determination unit 8c causes the line sensors 3 to execute a process of reading the test image G1.

[0072] By executing the process of step S102, data of a plurality of scanned images corresponding to the images of the plurality of partial regions A1 in the test image G1 is obtained. In this embodiment, data of two scanned images is obtained.

[0073] The image determination unit 8c acquires data of the two read images from the two line sensors 3, and moves the process to step S103.

[0074] <Process S103> In step S103, the image determination unit 8c executes the image quality determination process based on the data of the plurality of read images obtained in step S102.

[0075] In the image quality determination process, the image determination unit 8c classifies the data of each of the plurality of read images into first read image data and second read image data. The first read image data is data of the non-overlapping area A2 in each of the plurality of partial areas A1. The second read image data is data of the overlapping area A3 in each of the plurality of partial areas A1.

[0076] Furthermore, the image determination unit 8c determines the permissible conditions for the first read image data and the second read image data for each partial area A1 individually.

[0077] For example, the tolerance conditions include conditions such as the tolerance of the positional deviation of the multiple element images included in the test image G1 and the tolerance of the difference in values ​​of the multiple pixel data constituting each of the multiple element images.

[0078] In the present embodiment, the image determination unit 8c classifies each of the plurality of reference image data into first reference image data corresponding to the non-overlapping area A2 and second reference image data corresponding to the overlapping area A3. Each of the plurality of reference image data may be classified into the first reference image data and the second reference image data in advance.

[0079] Furthermore, the image determination unit 8c determines, for each partial area A1, whether or not the first read image data satisfies the permissible condition based on the first reference image data.

[0080] Furthermore, the image determination unit 8c determines, for each partial area A1, whether or not the second read image data satisfies the permissible condition based on the second reference image data.

[0081] The image determination unit 8c determines whether the non-overlapping region A2 and the overlapping region A3 in each of the partial regions A1 are in a normal image state in which the permissible condition is satisfied, or an abnormal image state in which the permissible condition is not satisfied.

[0082] After executing the process of step S103, the image determination unit 8c shifts the process to step S104.

[0083] <Process S104> In step S104, the image determination unit 8c selects the next process to be executed depending on whether or not there is an area determined to be an image abnormality among the partial areas A1.

[0084] The image determination unit 8c shifts the process to step S105 when the partial regions A1 include an area determined to be an image abnormality. On the other hand, the image determination unit 8c ends the image quality determination process when the partial regions A1 include no area determined to be an image abnormality.

[0085] <Process S105> In step S105, the image determination unit 8c selects the next process to be executed depending on whether or not there is a contradiction in the determination result of the allowable conditions for the overlapping area A3.

[0086] A contradiction in the judgment results of the tolerance conditions is a situation in which only one of the data of two adjacent partial areas in the multiple partial areas A1 is judged to not satisfy the tolerance conditions for the overlapping area A3 common to the two adjacent partial areas.

[0087] A first example of a situation in which there is no contradiction in the judgment results of the tolerance conditions is a situation in which both of the data for the two adjacent partial regions are judged to not satisfy the tolerance conditions for the overlapping area A3 common to the two adjacent partial regions.

[0088] A second example of a situation where there is no contradiction in the determination results of the allowable conditions is a situation where both of the data of the two adjacent partial areas are determined to satisfy the allowable conditions for the overlapping area A3 common to the two adjacent partial areas. In the second example, it is determined that any of the first read image data does not satisfy the allowable conditions.

[0089] The image determination unit 8c shifts the process to step S106 when there is no contradiction in the determination result of the allowable conditions for the overlapping area A3. On the other hand, the image determination unit 8c shifts the process to step S107 when there is a contradiction in the determination result of the allowable conditions for the overlapping area A3.

[0090] That is, when it is determined that neither of the data of the two adjacent partial regions in the multiple partial regions A1 satisfies the tolerance condition for the overlapping region A3 common to the two adjacent partial regions, the processing of step S106 is executed.

[0091] On the other hand, if it is determined that only one of the data of the two adjacent partial regions in the multiple partial regions A1 does not satisfy the tolerance condition for the overlapping region A3 common to the two adjacent partial regions, processing of step S107 is executed.

[0092] <Process S106> In step S106, the error processor 8d executes a predetermined first error process. A specific example of the first error process will be described later. After executing the first error process, the error processor 8d ends the image quality determination process.

[0093] <Process S107> In step S107, the error processor 8d executes a second error process different from the first error process. A specific example of the second error process will be described later. After executing the second error process, the error processor 8d ends the image quality determination process.

[0094] [First error handling] Next, an example of a procedure for the first error process will be described with reference to the flowchart shown in FIG.

[0095] In the following description, S201, S202, ... represent identification codes of a plurality of steps in the first error processing. In the first error processing, the processing of step S201 is executed first.

[0096] <Process S201> In step S201, the error processor 8d prohibits new printing processes.

[0097] For example, if the image inspection process is executed in the middle of a continuous printing process, the subsequent printing process is not executed until the prohibition of the printing process is released.

[0098] After executing the process of step S201, the error processing unit 8d shifts the process to step S202.

[0099] <Process S202> In step S202, the error processor 8d executes a first inquiry process, which includes a process of notifying the state in which the image abnormality is detected.

[0100] Furthermore, the first inquiry process includes a process of inquiring whether to re-execute the image inspection process or to release the prohibition of the print process.

[0101] For example, the error processor 8d executes the first inquiry process through the human interface device 800 of the image forming apparatus .

[0102] Moreover, the error processing unit 8d may transmit inquiry information to the host device 7 through the communication device 85, thereby executing the first inquiry process through the human interface device 70 of the host device 7.

[0103] The user checks the notification information from the first inquiry process and then performs an adjustment selected from a plurality of adjustment candidates. For example, the plurality of adjustment candidates include performing an operation on the operation device 801 to cause the image forming apparatus 10 to execute various adjustment processes such as a head cleaning process or a print density correction process.

[0104] Furthermore, the plurality of adjustment suggestions include cleaning of the sheet transport device 2 or the transport path 200.

[0105] After executing the process of step S202, the error processing unit 8d shifts the process to step S203.

[0106] <Process S203> In step S203, the error processor 8d selects the next process depending on whether or not a re-examination instruction has been input in response to the first inquiry process. The re-examination instruction is an instruction requesting re-execution of the image inspection process.

[0107] Usually, the user performs an operation corresponding to the re-inspection instruction on the human interface device 800 of the image forming apparatus 10 or the human interface device 70 of the host device 7 after carrying out the adjustment measures.

[0108] The error processing unit 8d shifts the process to step S204 if the reexamination instruction has not been input, and shifts the process to step S205 if the reexamination instruction has been input.

[0109] <Process S204> In step S204, the error processor 8d selects the next process depending on whether or not a release instruction has been input in response to the first inquiry process. The release instruction is an instruction requesting the release of the prohibition of the print process.

[0110] When the user visually determines that the image quality of the test image G1 is acceptable, the user performs an operation corresponding to the release instruction on the human interface device 800 of the image forming apparatus 10 or the human interface device 70 of the host device 7 .

[0111] The error processing unit 8d shifts the process to step S203 if the release instruction has not been input, and shifts the process to step S206 if the release instruction has been input.

[0112] <Process S205> In step S205, the error processor 8d starts the image inspection process. As a result, the processes from step S101 onward shown in Fig. 4 are executed again. The error processor 8d ends the first error process when the image inspection process starts.

[0113] <Process S206> In step S206, the error processor 8d releases the prohibition of the print process, so that the image forming apparatus 10 transitions to a state in which the print process can be executed.

[0114] After executing the process of step S206, the error processing section 8d ends the first error process.

[0115] [Second error handling] Next, an example of a procedure for the second error process will be described with reference to the flowchart shown in FIG.

[0116] In the following description, S301, S302, ... represent identification codes of a plurality of steps in the second error processing. In the second error processing, the processing of step S301 is executed first.

[0117] <Process S301> In step S301, the error processor 8d prohibits new printing processes, similarly to step S201.

[0118] After executing the process of step S301, the error processing unit 8d shifts the process to step S302.

[0119] <Process S302> In step S302, the error processor 8d executes a second inquiry process, which includes a process of notifying a state in which the image abnormality is detected and a state in which a contradiction occurs in the determination result of the allowable condition.

[0120] Furthermore, the second inquiry process includes a process of inquiring whether to re-execute the image inspection process or to execute an invalid sensor setting.

[0121] The invalid sensor setting is to set one of the two adjacent line sensors corresponding to the overlap area A3 where the conflict occurs as an invalid sensor.

[0122] The two adjacent line sensors are the two that correspond to the overlapping area A3 where the contradiction occurred among the multiple line sensors 3. In other words, the two adjacent line sensors are the two that correspond to the overlapping area A3 that caused the second error processing among the multiple line sensors 3.

[0123] When the contradiction occurs regarding the overlapping area A3, there is a possibility that one of the two adjacent line sensors is abnormal. The user checks the notification information by the second inquiry process and then judges the status of the two adjacent line sensors.

[0124] In this embodiment, the image forming apparatus 10 includes two line sensors 3. In this case, these two line sensors 3 are the two adjacent line sensors.

[0125] For example, the error processor 8d executes the second inquiry process through the human interface device 800 of the image forming apparatus .

[0126] Moreover, the error processing unit 8d may transmit inquiry information to the host device through the communication device 85, thereby executing the second inquiry processing through the display unit of the host device.

[0127] The user confirms the notification information from the second inquiry process, and then performs the adjustment action selected from the multiple adjustment candidates.

[0128] After executing the process of step S302, the error processing unit 8d shifts the process to step S303.

[0129] <Process S303> In step S303, similarly to step S203, the error processing unit 8d selects the next process depending on whether or not the re-examination instruction has been input in response to the second inquiry process.

[0130] Usually, the user performs an operation corresponding to the re-inspection instruction on the human interface device 800 of the image forming apparatus 10 or the human interface device 70 of the host device 7 after carrying out the adjustment measures.

[0131] The error processing unit 8d shifts the process to step S304 if the reexamination instruction has not been input, and shifts the process to step S305 if the reexamination instruction has been input.

[0132] <Process S304> In step S304, the error processing unit 8d selects the next process depending on whether or not an invalid setting instruction has been input in response to the second inquiry process.

[0133] The invalid setting instruction is an instruction to request to set one of the two adjacent line sensors corresponding to the overlap area A3 where the conflict has occurred as an invalid sensor. Input of the invalid setting instruction is an example of input of invalid instruction information.

[0134] When the user determines that one of the two adjacent line sensors corresponding to the discrepancy regarding the overlap area A3 is abnormal, the user performs an operation corresponding to the invalid setting instruction on the human interface device 800 of the image forming device 10 or the human interface device 70 of the host device 7.

[0135] The error processing unit 8d shifts the process to step S303 if the invalid setting instruction has not been input, and shifts the process to step S306 if the invalid setting instruction has been input.

[0136] <Process S305> In step S305, the error processor 8d starts the image inspection process. As a result, the processes from step S101 onward shown in Fig. 4 are executed again. The error processor 8d ends the second error process when the image inspection process starts.

[0137] <Process S306> In step S306, the error processing unit 8d sets one of the two adjacent line sensors as the invalid sensor in accordance with the invalid setting instruction.

[0138] In the image quality determination process in step S103, the image determination unit 8c determines the permissible condition only for data corresponding to valid line sensors that are not set as the invalid sensors among the multiple line sensors 3 (see FIG. 4).

[0139] After executing the process of step S306, the error processing unit 8d shifts the process to step S307.

[0140] <Process S307> In step S307, the error processor 8d releases the prohibition of the print process, so that the image forming apparatus 10 transitions to a state in which the print process can be executed.

[0141] After executing the process of step S307, the error processing section 8d ends the second error process.

[0142] By adopting the image forming apparatus 10, the line sensor 3 used to determine the quality of an output image can be standardized among a plurality of models.

[0143] Furthermore, by determining whether or not there is a contradiction in the overlapping area A3, it is possible to grasp whether or not an abnormality has occurred in some of the line sensors 3.

[0144] Furthermore, by setting the invalid sensor, even if an abnormality occurs in one of the multiple line sensors 3, the image inspection process can be executed using the valid line sensor until the abnormal part is replaced.

[0145] [Second embodiment] Next, an image forming apparatus 10A according to a second embodiment will be described with reference to Fig. 7. In Fig. 7, the same components as those shown in Fig. 3 are denoted by the same reference numerals.

[0146] The following describes the image forming apparatus 10A in terms of the differences from the image forming apparatus 10. The image forming apparatus 10A is different from the image forming apparatus 10 in that it includes three line sensors 3.

[0147] In the image forming apparatus 10A, the three line sensors 3 are arranged along the width direction D2 with their positions in the width direction D2 partially overlapping each other. The three line sensors 3 read images of three partial areas A1, which are parts of the sheet passing area in the width direction D2, from the sheet 9.

[0148] Each of the three partial areas A1 includes a non-overlapping area A2 and an overlapping area A3. In the image forming apparatus 10A, the sheet passing area is divided into three non-overlapping areas A2 and two overlapping areas A3.

[0149] In the image forming device 10A, one of the two white reference members 4 is arranged opposite two of the three line sensors 3, and the other of the two white reference members 4 is arranged opposite the remaining one of the three line sensors 3.

[0150] In the image forming apparatus 10A as well, the print control unit 8b, the image determination unit 8c, and the error processing unit 8d execute the image inspection process (see FIGS. 4 to 6).

[0151] When the image forming apparatus 10A is employed, the same effects as when the image forming apparatus 10 is employed can be obtained.

[0152] [Application example] The image forming apparatus 10A may include four or more line sensors 3. [Explanation of symbols]

[0153] 2: Sheet transport device 3: Line sensor 4: White reference material 5: Printing device 7: Host device 8: Control device 10, 10A: Image forming apparatus 70: Human interface devices 800: Human interface devices A1: Partial area A2: Non-overlapping area A3: Overlapping area

Claims

1. a printing device for forming an image on a sheet conveyed along a conveying path; a plurality of line sensors disposed downstream in a sheet conveying direction with respect to the printing device, along a width direction intersecting the sheet conveying direction, with each line sensor reading images of a plurality of partial areas from the sheet, each of which includes a non-overlapping area that is a part of a sheet passing area in the width direction and does not overlap with an adjacent area, and an overlapping area that overlaps with an adjacent area; an image determination unit that determines whether data of each of a plurality of read images obtained by the plurality of line sensors satisfies or does not satisfy an allowable condition based on each of a plurality of reference image data representing images of the plurality of partial regions; an error processing unit that executes a predetermined error process when it is determined that any of the data of the plurality of read images does not satisfy the permissible condition.

2. the image determination unit determines the permissible condition individually for the data of the non-overlapping region and the data of the overlapping region in each of the plurality of partial regions; the error processing unit executes a first error process when it is determined that neither of data of two adjacent partial regions in the plurality of partial regions satisfies the allowable condition for the overlapping region common to the two adjacent partial regions; The image forming device of claim 1, wherein the error processing unit executes a second error processing different from the first error processing when it is determined that only one of the data of the two adjacent partial areas does not satisfy the tolerance condition for the overlapping area common to the two adjacent partial areas.

3. The second error processing includes: a process of inquiring through a human interface device to set one of the two adjacent line sensors corresponding to the overlapping region that caused the second error process as an invalid sensor among the plurality of line sensors; and when invalid instruction information instructing the setting of the invalid sensor is input through the human interface device, a process of setting one of the two adjacent line sensors as the invalid sensor in accordance with the invalid instruction information, The image forming apparatus according to claim 2 , wherein the image determination section determines the permissible condition only for data corresponding to an effective line sensor that is not set as the ineffective sensor among the plurality of line sensors.

Images