JP2019072893A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus capable of prohibiting only execution of double-sided printing when a double-sided printing abnormality easily occurs.SOLUTION: An image forming apparatus includes: a printing section; a notification section; and a control section which recognizes the normal number of times in which printing can be performed without the occurrence of an abnormality as for double-sided printing for the latest prescribed number of sheets, recognizes the abnormal number of times in which printing cannot be performed because of the occurrence of a double-sided printing abnormality to be an abnormality which does not occur during execution of one-sided printing, determines a value that the abnormal number of times is divided by the total number of times of the normal number of times and the abnormal number of times as a generation rate of the double-sided printing abnormality, and causes the notification section to notify the generation rate when the generation rate is a predetermined threshold or more.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus that prints an image on a sheet.

  Conventionally, an image forming apparatus capable of detecting the degree of abnormality occurring in an image forming apparatus is known. Such an image forming apparatus is disclosed, for example, in Patent Document 1.

  The image forming apparatus (printing system) of Patent Document 1 performs a process of detecting the degree of abnormality during printing. Then, if the degree of the detected abnormality is large (if it is larger than a predetermined first degree), the image forming apparatus of Patent Document 1 cancels the printing in progress.

JP, 2009-78886, A

  If an abnormality such as a jam occurs while printing is being performed by the image forming apparatus, problems such as breakage of the sheet may occur. Therefore, depending on the image forming apparatus, when the abnormality frequently occurs, the user may be notified that the image forming apparatus is in the abnormal state. For example, the user who has received the notification prohibits execution of printing in the image forming apparatus and performs operations such as requesting maintenance of the image forming apparatus.

  Here, some image forming apparatuses can execute single-sided printing and double-sided printing. In an image forming apparatus capable of single-sided printing and double-sided printing, double-sided printing abnormality may occur which is an abnormality that does not occur when single-sided printing is performed at the time of double-sided printing.

  If the frequently occurring abnormality is only a double-sided printing abnormality, even if single-sided printing is performed, the possibility of the abnormality being generated is low. However, in this case, if the user is notified that the image forming apparatus is in an abnormal state, there is a possibility that execution of single-sided printing as well as double-sided printing may be prohibited. Therefore, it is disadvantageous for the user who wants to perform single-sided printing.

  The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an image forming apparatus capable of prohibiting only execution of double-sided printing when double-sided printing abnormality is likely to occur. I assume.

  In order to achieve the above object, an image forming apparatus according to one aspect of the present invention is abnormal in a printing unit capable of performing single-sided printing and double-sided printing, a notifying unit performing notification, and double-sided printing for a predetermined number of nearest sheets. Recognizes the number of normals that could be printed without occurrence of a problem, and recognize the number of abnormal times that could not be printed because a double-sided printing abnormality occurred which is an abnormality that does not occur when single-sided printing is performed. Control to have the notification unit report the occurrence rate if the occurrence rate is equal to or greater than a predetermined threshold, and calculates the occurrence rate of double-sided printing as a value obtained by dividing the value by the total number of And a unit.

  In the configuration of the present invention, the control unit performs abnormality occurrence rate calculation processing for obtaining a value obtained by dividing the number of abnormalities by the total number of normal times and the number of abnormalities as the incidence rate of double-sided printing abnormality. Here, the number of times of normal operation is the number of times of printing without occurrence of abnormality. The number of times of abnormality is the number of times printing can not be performed because a double-sided printing abnormality that is an abnormality that does not occur when single-sided printing is performed has occurred. That is, in the abnormality occurrence rate calculation process by the control unit, the number of times printing can not be performed because an abnormality that may occur even when single-sided printing is performed is not reflected. This makes it possible to accurately determine the incidence rate of double-sided printing abnormality.

  Further, the control unit causes the notification unit to notify the occurrence rate of the both-side printing abnormality when the occurrence rate of the both-side printing abnormality is equal to or more than a predetermined threshold. The user who has received the notification recognizes that double-sided printing abnormality is likely to occur. This makes it possible to prohibit only the execution of double-sided printing when double-sided printing abnormality is likely to occur (the execution of single-sided printing is not unnecessarily prohibited).

  According to the configuration of the present invention, only the execution of double-sided printing can be prohibited when double-sided printing abnormality is likely to occur.

FIG. 1 is a block diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view showing the configuration of a printing unit of the image forming apparatus according to the embodiment of the present invention. It is a flowchart which shows the flow of the process (process which updates double-sided printing information) which the control part of the image forming apparatus by one Embodiment of this invention performs. It is a flowchart which shows the flow of abnormality incidence rate calculation processing which the control part of the image forming apparatus by one Embodiment of this invention performs. It is a flowchart which shows the flow of the execution / non-execution judgment processing which the control part of the image forming apparatus by one Embodiment of this invention performs. It is a figure which shows the 1st alerting | reporting screen which the operating panel of the image forming apparatus by one Embodiment of this invention displays. It is a figure which shows the 2nd alerting | reporting screen which the operating panel of the image forming apparatus by one Embodiment of this invention displays. It is a figure which shows the 3rd alerting | reporting screen which the operating panel of the image forming apparatus by one Embodiment of this invention displays.

<Configuration of Image Forming Apparatus>
As shown in FIG. 1, the image forming apparatus 100 of the present embodiment includes a control unit 1. The control unit 1 includes a CPU 11, a memory 12 and an image processing module 13. The CPU 11 operates based on control programs and data, and performs processing for controlling each part of the image forming apparatus 100. The memory 12 stores control programs and data for operating the CPU 11. The image processing module 13 includes a dedicated circuit and memory for performing image processing. The control unit 1 uses the image processing module 13 to perform image processing on image data of an image to be printed.

  The image forming apparatus 100 further includes an image reading unit 2 and a printing unit 3. The image reading unit 2 and the printing unit 3 are connected to the control unit 1. The control unit 1 controls the reading operation of the image reading unit 2 and controls the printing operation of the printing unit 3.

  The image reading unit 2 includes an optical system member (not shown) that optically reads an original such as a light source or an image sensor. The image reading unit 2 reads a document and generates image data of the document.

  The printing unit 3 has a configuration as shown in FIG. When printing is performed, the printing unit 3 conveys the sheet P, forms an image to be printed, and prints the image on the sheet P being conveyed. For example, the printing unit 3 performs printing based on the image data of the document read by the image reading unit 2.

  The printing unit 3 includes the sheet conveyance path 30 (the main conveyance path 30A and the reverse conveyance path 30B), and includes a plurality of conveyance roller pairs 31 for conveying the sheet P along the sheet conveyance path 30. The printing unit 3 further includes a sheet feeding roller pair 32, an image forming unit 33, and a fixing roller pair 34.

  The sheet feeding roller pair 32 feeds the sheet P accommodated in the sheet cassette 35 to the sheet conveyance path 30. For example, a plurality of sheet cassettes 35 are attached to the image forming apparatus 100. In this case, one sheet feed roller pair 32 is assigned to each of the plurality of sheet cassettes 35. The sheet sizes that can be accommodated in the plurality of sheet cassettes 35 may be the same or different.

  The sheet cassette 35 is slidably provided with a restriction guide 351 that abuts on the side surface of the sheet P and positions the sheet P. The restriction guide 351 has a first cursor that can slide in the sheet conveyance direction (sheet feeding direction) and a second cursor that can slide in the width direction (direction perpendicular to the sheet of FIG. 2) orthogonal to the sheet conveyance direction. including. By sliding the first cursor in the sheet conveyance direction, the size (sheet length in the sheet conveyance direction) of the sheet P which can be accommodated in the sheet cassette 35 can be changed. By sliding the second cursor in the width direction, it is possible to change the size in the width direction of the sheets P that can be accommodated in the sheet cassette 35 (the sheet length in the width direction).

  The sheet P fed from the sheet cassette 35 to the sheet conveyance path 30 is conveyed along the sheet conveyance path 30. The sheet P conveyed along the sheet conveyance path 30 passes through the printing position PP (transfer nip) and the fixing position FP (fixing nip) in this order. The transport roller pair 31 transports the sheet P in the sheet transport path 30. The printed sheet P is finally discharged to the discharge tray 36.

  Among the plurality of conveyance roller pairs 31, the conveyance roller pair 31 (the registration roller pair 31R in the following description) is installed at a registration position that is a position upstream of the printing position PP of the sheet conveyance path 30 in the sheet conveyance direction. Is called rotation and rotation stop when printing is performed. The registration roller pair 31R stops rotating when the leading end of the sheet P reaches the registration position. That is, the registration roller pair 31R temporarily stops the progress of the sheet P conveyed toward the printing position PP at the registration position.

  Further, among the plurality of transport roller pairs 31, the transport roller pair 31 installed at the discharge position which is the most downstream position of the paper transport direction of the paper transport path 30 (hereinafter referred to as discharge roller pair 31D) When the sheet P is discharged to the discharge tray 36, it rotates forward. Then, the discharge roller pair 31D reversely rotates when the sheet P is switched back. Details will be described later.

  The image forming unit 33 includes a photosensitive drum 331 and a transfer roller 332. Although not shown, the image forming unit 33 includes a charging device for charging the circumferential surface of the photosensitive drum 331, an exposure device for forming an electrostatic latent image on the circumferential surface of the photosensitive drum 331, and the photosensitive drum 331. And a developing device for developing the electrostatic latent image on the circumferential surface of the toner into a toner image. The photosensitive drum 331 and the transfer roller 332 are in pressure contact with each other to form a transfer nip (the position of the transfer nip is the printing position PP). The image forming unit 33 transfers the toner image to the sheet P passing the printing position PP.

  The fixing roller pair 34 includes a heating roller and a pressure roller. The heating roller incorporates a heater. The pressure roller is in pressure contact with the heating roller and forms a fixing nip with the heating roller (the position of the fixing nip is the fixing position FP). The fixing roller pair 34 fixes the toner image on the sheet P by heating and pressing the sheet P (the sheet P sent from the printing position PP) passing through the fixing position FP.

  The printing unit 3 is configured to be capable of single-sided printing and double-sided printing. The printing unit 3 prints an image only on one side of the sheet P when single-sided printing is performed. On the other hand, the printing unit 3 prints an image on both sides of the sheet P when performing double-sided printing.

  Only the main conveyance path 30A is used for single-sided printing, and both the main conveyance path 30A and the reverse conveyance path 30B are used for double-sided printing. The main conveyance path 30A passes the printing position PP and the fixing position FP in this order from the installation position of the sheet cassette 35, and reaches the installation position of the discharge tray 36. The reverse conveyance path 30B connects the downstream position DP of the main conveyance path 30A and the upstream position UP. In the main conveyance path 3A, the downstream position DP is a position downstream of the fixing position FP (print position PP) in the sheet conveyance direction, and the upstream position UP is a position upstream of the print position PP in the sheet conveyance direction.

  When single-sided printing is performed, the printing unit 3 conveys the sheet P fed to the main conveyance path 30A toward the printing position PP, and prints an image on one side of the sheet P being conveyed. Then, the printing unit 3 conveys the sheet P on which the image is printed on one side as it is along the main conveyance path 30A, and discharges the sheet P to the discharge tray 36.

  When double-sided printing is performed, the printing unit 3 conveys the sheet P fed to the main conveyance path 30A toward the printing position PP as in the single-sided printing, and prints an image on one side of the sheet P being conveyed. Do. Thereafter, the printing unit 3 uses the reverse conveyance path 30B to make a single-sided printing sheet after the paper P on which the image is printed on one side (here, referred to as single-sided printing paper P) passes the downstream position DP of the main conveyance path 30A. A process of returning P to the upstream position UP of the main conveyance path 30A is performed. By performing the processing, the orientation of the front and back of single-sided printing paper P is reversed. In the following description, the process of returning the single-sided print sheet P from the downstream position DP of the main conveyance path 30A to the upstream position UP (a process of reversing the direction of front and back of single-sided print sheet P) is referred to as a reverse process.

  Specifically, in the printing unit 3, after the rear end of the single-sided printing paper P passes the downstream position DP, before the rear end of the single-sided printing paper P passes the discharge position (the installation position of the discharge roller pair 31D) , The discharge roller pair 31D is reversely rotated. That is, the printing unit 3 switches back the single-sided printing paper P (reverses the front and back of the single-sided printing paper P). Thereby, the single-sided printing paper P is drawn into the reverse conveyance path 30B from the downstream position DP.

  After pulling the single-sided printing paper P into the reverse conveyance path 30B, the printing unit 3 conveys the single-sided printing paper P along the reverse conveyance path 30B, and returns the single-sided printing paper P from the upstream position UP to the main conveyance path 30A. Thereafter, the printing unit 3 transports the single-sided printing sheet P returned to the main transport path 30A to the printing position PP. Thereby, the single-sided printing paper P passes through the printing position PP. At this time, since the orientation of the front and back of single-sided printing paper P is reversed, an image is printed on the unprinted side of single-sided printing paper P. The printing unit 3 conveys the sheet P on which the image is printed on both sides along the main conveyance path 30A and discharges the sheet P to the discharge tray 36.

  Returning to FIG. 1, the size sensor 111 is connected to the control unit 1. The size sensor 111 is a sensor that changes the output value according to the position of the restriction guide 351. The control unit 1 detects the size (the length of each sheet in the sheet conveyance direction and the width direction) of the sheet P stored in the sheet cassette 35 based on the output value of the size sensor 111.

  Further, a conveyance sensor 112 is connected to the control unit 1. The conveyance sensor 112 is installed in the sheet conveyance path 30. The installation number of the conveyance sensor 112 is plural, and a plurality of predetermined positions of the sheet conveyance path 30 are respectively set as detection positions of the conveyance sensor 112. Each of the plurality of conveyance sensors 112 changes the output value according to the presence or absence of the sheet P at the corresponding detection position. Based on the output values of the plurality of conveyance sensors 112, the control unit 1 detects the conveyance state of the sheet P in the sheet conveyance path 30 (the arrival of the leading end and the trailing end of the sheet P at each detection position).

  Here, reference numerals 112a to 112g are attached to the plurality of conveyance sensors 112 installed in the sheet conveyance path 30, and installation positions (detection positions) of the conveyance sensors 112 will be described. In addition, the installation position of each conveyance sensor 112 demonstrated below is an example, the conveyance sensor 112 does not need to be installed in the position mentioned here, and the conveyance sensor 112 may be installed in another position.

  As shown in FIG. 2, the conveyance sensor 112 a is installed at a position downstream of the installation position of the paper feed roller pair 32 (near the installation position of the paper feed roller pair 32). When the plurality of sheet cassettes 35 are attached to the image forming apparatus 100, that is, when the plurality of sheet feeding roller pairs 32 are disposed in the image forming apparatus 100, the number of the conveyance sensors 112a is plural.

  The conveyance sensor 112b is installed at a position upstream of the installation position of the registration roller pair 31R in the sheet conveyance direction (near the installation position of the registration roller pair 31R). The conveyance sensor 112 c is installed at a position downstream of the fixing position FP in the sheet conveyance direction (near the installation position of the fixing roller pair 34). The conveyance sensor 112 d is installed at a position upstream of the installation position of the discharge roller 31 D in the sheet conveyance direction (near the installation position of the discharge roller pair 31 D).

  The conveyance sensor 112e is installed at a position near the downstream position DP of the reverse conveyance path 30B. The conveyance sensor 112 f is disposed between the downstream position DP and the upstream position UP of the reverse conveyance path 30 </ b> B. The installation number and installation position of the paper transport path 112f are appropriately changed according to the installation number and installation position of the transport roller pair 31 installed in the reverse transport path 30B, the length of the transport path of the reverse transport path 30B, and the like. The transport sensor 112g is installed at a position near the upstream position UP of the reverse transport path 30B.

  Returning to FIG. 1, the image forming apparatus 100 includes the operation panel 4. The operation panel 4 corresponds to a "notification unit".

  Operation panel 4 includes touch panel display 41. The touch panel display 41 displays a setting screen on which the software button is arranged, and receives a touch operation on the software button from the user. The operation panel 4 also includes a plurality of hardware buttons 42. The hardware button 42 includes, for example, a start button for receiving a print instruction from the user.

  The operation panel 4 is connected to the control unit 1. Control unit 1 controls the display operation of operation panel 4 (touch panel display 41). Further, the control unit 1 detects an operation (a touch operation on the touch panel display 41 and a press operation on the hardware key 42) performed on the operation panel 4.

  The image forming apparatus 100 further includes a storage unit 5. The storage unit 5 includes, for example, a non-volatile storage device such as a ROM (EEPROM or the like) or an HDD. That is, even if the main power supply of the image forming apparatus 100 is shut off, the information stored in the storage unit 5 does not disappear.

  The storage unit 5 is connected to the control unit 1. The control unit 1 writes information to the storage unit 5 and reads information from the storage unit 5. For example, control unit 1 causes storage unit 5 to store double-sided printing information 10 to be referred to when performing an abnormality occurrence rate calculation process described later. The double-sided printing information 10 will be described in detail later.

  The image forming apparatus 100 further includes a communication unit 6. The communication unit 6 is an interface for connecting the image forming apparatus 100 to a network NT such as a LAN, and includes a communication circuit, a communication memory, a communication connector, and the like. A user terminal 200 used by a user of the image forming apparatus 100 is connected to the network NT. The user terminal 200 is, for example, a personal computer. Further, connected to the network NT is a server 300 (hereinafter, referred to as a maintenance server 300) of a maintenance provider who performs maintenance of the image forming apparatus 100.

  The communication unit 6 is connected to the control unit 1. The control unit 1 controls the communication performed by the communication unit 6. The control unit 1 communicates with the user terminal 200 and the maintenance server 300 using the communication unit 6. For example, when the image forming apparatus 100 is used as a printer, a print instruction including print data and print conditions (for example, a sheet size used for printing) is transmitted from the user terminal 200. The communication unit 6 receives the print instruction from the user terminal 200 (accepts the print instruction from the user).

<Control during printing>
When the control unit 1 receives a print instruction from the user, the control unit 1 recognizes the sheet size designated by the user. For example, the specification of the paper size is accepted from operation panel 4 from the user. When the image forming apparatus 100 is used as a printer, the print instruction from the user terminal 200 includes the sheet size designated by the user.

  When recognizing the sheet size designated by the user, the control unit 1 sets the sheet cassette 35 containing the sheet P of the recognized size as a sheet feed source, and gives a print execution instruction to the printing unit 3. When the printing unit 3 receives the print execution instruction, the printing unit 3 feeds the sheets P stored in the sheet cassette 35 of the sheet feed source to the sheet conveyance path 30. Then, the printing unit 3 conveys the sheet P along the sheet conveyance path 30, and prints an image on the sheet P being conveyed.

  The control unit 1 performs jam error detection to detect whether or not a jam error has occurred in the sheet conveyance path 30 during execution of single-sided printing and double-sided printing by the printing unit 3. The jam error detection by the control unit 1 is performed based on each output value of the plurality of conveyance sensors 112. A non-feed error in which the sheet P is not fed from the sheet cassette 35 to the sheet conveyance path 30 is also detected as a jam error.

  For example, the control unit 1 starts timing after detecting the arrival of the leading end of the sheet P at a detection position of a certain conveyance sensor 112 (here, referred to as a first conveyance sensor 112) among the plurality of conveyance sensors 112. Then, the control unit 1 detects the arrival of the leading end of the sheet P at the detection position of the first conveyance sensor 112, and when a predetermined time has elapsed, the conveyance sensor located downstream of the first conveyance sensor 112 in the sheet conveyance direction It is detected whether or not the leading end of the sheet P has reached the detection position of 112 (here, referred to as a second conveyance sensor 112). As a result, if arrival of the leading edge of the sheet P can not be detected, the control unit 1 determines that a jam error has occurred. The predetermined time in this case is the time required for the sheet P to advance between the detection position of the first conveyance sensor 112 and the detection position of the second conveyance sensor 112, and the detection position of the first conveyance sensor 112 and the second position It can be previously determined based on the sheet conveyance distance between the detection position of the conveyance sensor 112 and the sheet conveyance speed.

  The control unit 1 detects that the leading edge of the sheet P is detected at a detection position of a conveyance sensor 112 among the plurality of conveyance sensors 112, and then detects the trailing edge of the sheet P at the same detection position even after a predetermined time has elapsed. If the passage can not be detected, it is determined that a jam error has occurred. The predetermined time in this case is the time required for the trailing edge of the sheet P to pass the same detection position after the leading edge of the sheet P reaches the detection position of a certain conveyance sensor 112, and the sheet size (the length in the conveyance direction) And the sheet conveyance speed in advance.

  The control unit 1 interrupts printing by the printing unit 3 when a jam error occurs. Then, the control unit 1 causes the operation panel 4 to display an error message indicating that a jam error has occurred. As a result, the user performs a jam processing operation (operation for removing the jammed sheet P from the sheet conveyance path 30).

  For example, in a jam handling operation by the user, the side cover (not shown) of the image forming apparatus 100 is opened. When the side cover is open, the sheet conveyance path 30 is exposed. Thus, the jammed sheet P can be removed from the sheet conveyance path 30. Alternatively, when the sheet cassette 35 is pulled out of the image forming apparatus 100, the sheet feeding roller pair 32 is exposed. Therefore, when the jammed sheet P remains on the sheet feeding roller pair 32, the jammed sheet P can be removed by pulling out the sheet cassette 35.

  After the jam error occurs, the control unit 1 determines whether the user has finished the jam processing operation. When the control unit 1 detects that the side cover opened after the occurrence of the jam error is closed, it determines that the jam processing operation is completed. Alternatively, when it is detected that the sheet cassette 35 pulled out after the occurrence of the jam error is returned, the control unit 1 determines that the jam processing operation is completed. After the jam processing operation by the user is completed, the control unit 1 resumes the printing by the printing unit 3.

<Prohibition of double-sided printing>
The control unit 1 determines whether or not an abnormality such as a jam error has occurred each time double-sided printing is performed by the printing unit 3. When an abnormality occurs, the control unit 1 determines whether the generated abnormality is an abnormality that does not occur when performing single-sided printing, that is, an abnormality that can occur only when performing double-sided printing (hereinafter referred to as an abnormal both-side printing). To judge. In other words, the control unit 1 determines whether or not the generated abnormality is an abnormality (hereinafter, referred to as a common abnormality) that can also be generated when performing single-sided printing. Then, when the occurrence frequency of the double-sided printing abnormality is high, the control unit 1 performs a predetermined countermeasure process.

  The control unit 1 recognizes the printing result of double-sided printing each time one double-sided printing by the printing unit 3 is performed in order to determine whether or not the countermeasure process should be performed. The control unit 1 causes the storage unit 5 to store print result information indicating the print result.

  Here, the control unit 1 includes, in the duplex printing information 10, the printing result information of the latest predetermined number of sheets executed by the printing unit 3. For example, the predetermined number is ten. In a state where the number (10) of print result information corresponding to the predetermined number is already included in the duplex printing information 10, that is, in a state where the number of printed sheets of duplex printing by the printing unit 3 has already reached the predetermined number. When the printing unit 3 newly executes double-sided printing, the control unit 1 deletes the oldest print result information from the double-sided printing information 10. Then, the control unit 1 adds, to the double-sided printing information 10, print result information indicating the print result of the newly executed double-sided printing.

  The storage unit 5 stores the double-sided printing information 10 for each of a plurality of predetermined sheet length ranges (ranges of lengths in the sheet conveyance direction). For example, the sheet length range is classified into three of a first sheet length range, a second sheet length range, and a third sheet length range. In this example, three double-sided printing information 10 corresponding to the first sheet length range, the second sheet length range, and the third sheet length range are stored in the storage unit 5. The number of classifications of the sheet length range is not particularly limited, and the sheet length range may be classified into two or four or more.

  For example, the first sheet length range is 297 mm (corresponding to the length in the longitudinal direction of A4 size) or more, and the second sheet length range is not less than 297 mm (corresponding to the length in the longitudinal direction of A5 size) The third sheet length range is less than 210 mm.

  This will be specifically described below with reference to the flowchart shown in FIG. The flowchart illustrated in FIG. 3 starts when the printing unit 3 starts double-sided printing (when the printing unit 3 starts feeding the sheet P from the sheet cassette 35 to the sheet conveyance path 30). The printing unit 3 feeds the sheet P of the sheet cassette 35 set as the feed source by the control unit 1 to the sheet conveyance path 30. Then, the control unit 1 recognizes that the sheet P of the size corresponding to the sheet cassette 35 of the sheet feed source is conveyed.

  In step S1, the controller 1 prints an image on both sides of the sheet P fed from the sheet cassette 35 to the sheet conveyance path 30 without occurrence of abnormality, and discharges the sheet P on which the image is printed on both sides. It is determined whether the tray 36 has been properly discharged. In the case where no abnormality occurs during double-sided printing (when double-sided printing in progress is not interrupted), the sheet P on which images have been printed on both sides is the conveyance sensor 112d (see FIG. 2). It passes the detection position and is discharged to the discharge tray 36. Therefore, upon detecting that the trailing edge of the sheet P on which images have been printed on both sides has passed the detection position of the conveyance sensor 112d without occurrence of an abnormality, the control unit 1 determines that the sheet P has been discharged normally. Do.

  In step S1, when the control unit 1 determines that the sheet P is discharged normally, the process proceeds to step S2. In step S2, the control unit 1 recognizes the sheet length range corresponding to the size of the sheet P discharged normally among the three sheet length ranges, and performs double-sided printing of the recognized sheet length range. The information 10 is recognized as an update target. Then, the control unit 1 adds, as print result information, first information indicating that the sheet P has been discharged normally to the update target double-sided print information 10 (updates the update target double-sided print information 10).

  In step S1, when the control unit 1 determines that the sheet P is not discharged normally (an abnormality has occurred), the process proceeds to step S3. When the process proceeds to step S3, the control unit 1 determines whether the generated abnormality is a double-sided printing abnormality. Here, a method of determining whether or not an abnormality that occurs during execution of double-sided printing is double-sided printing abnormality will be described.

  In single-sided printing, the main conveyance path 30A is used but the reverse conveyance path 30B is not used. In duplex printing, both the main transport path 30A and the reverse transport path 30B are used. Therefore, when an abnormality occurs in the sheet P being conveyed along the main conveyance path 30A, the generated abnormality can not be said to be an abnormality in double-sided printing (an occurred abnormality also occurs when performing single-sided printing) Can) On the other hand, when an abnormality occurs in the sheet P being conveyed along the reverse conveyance path 30B, it can be said that the generated abnormality is a double-sided printing abnormality (the occurred abnormality can not occur when performing single-sided printing) ). Further, the sheet P is not switched back when performing single-sided printing, but is switched back when performing double-sided printing.

  From this, the control unit 1 causes an abnormality in a period from when the printing unit 3 switches back the single-sided printing paper P to when returning the single-sided printing paper P to the main conveyance path 20A (herein referred to as a reverse period). Then, it is determined that the abnormality is a duplex printing abnormality. For example, during the reversing period, when the rear end of the single-sided printing paper P on the way back to the main conveyance path 30A passes the detection position of the paper sensor 112g (see FIG. 2) from when the discharge roller pair 31D starts reverse rotation. Period until

  If the control unit 1 determines in step S3 that the generated abnormality is a duplex printing abnormality, the process proceeds to step S4. In step S4, the control unit 1 determines the sheet length corresponding to the size of the sheet P (the sheet P causing the occurrence of the double-sided printing abnormality) which has been conveyed at the occurrence of the double-sided printing abnormality among the three sheet length ranges. The double-sided printing information 10 in the recognized paper length range is recognized as an update target. Then, the control unit 1 adds, as the printing result information, the second information indicating that the double-sided printing abnormality has occurred to the double-sided printing information 10 to be updated (updates the double-sided printing information 10 to be updated).

  When the control unit 1 determines that the generated abnormality is not a double-sided printing abnormality but a common abnormality in step S3, the process proceeds to step S5. In step S5, the control unit 1 determines the sheet length corresponding to the size of the sheet P (the sheet P causing the common abnormality) being conveyed at the time of the common abnormality among the three sheet length ranges. The double-sided printing information 10 in the recognized paper length range is recognized as an update target. Then, the control unit 1 adds, as printing result information, third information (information indicating that the generated abnormality is not the double-sided printing abnormality) indicating the occurrence of the common abnormality to the update target double-sided printing information 10 (update Update the target duplex printing information 10).

  After the double-sided printing information 10 is updated, the process proceeds to step S6. In step S6, the control unit 1 determines whether a job involving double-sided printing has ended (whether double-sided printing for the number of sheets to be printed has ended). As a result, when the control unit 1 determines that the job has ended, the present flow ends, and when the control unit 1 determines that the job has not ended, the process proceeds to step S1. The control unit 1 also determines that the job has ended, even when an instruction to cancel the job has been received from the user. The operation panel 4 receives the cancel instruction. For example, a job may be canceled if an error occurs during double-sided printing (when double-sided printing in progress is interrupted).

  The double-sided printing information 10 obtained in this manner is referred to when the control unit 1 determines whether or not the countermeasure process should be performed. When determining whether or not the countermeasure process should be performed, the control unit 1 performs an abnormality occurrence rate calculation process for obtaining the incidence rate of the both-side printing abnormality based on the both-side printing information 10. The abnormality occurrence rate calculation process by the control unit 1 is performed for each of a plurality of sheet length ranges.

  The flow of the abnormality occurrence rate calculation process performed by the control unit 1 will be described below with reference to the flowchart shown in FIG. The flowchart shown in FIG. 4 starts when the control unit 1 determines that a predetermined check time has come. The control unit 1 determines that the check time has come when the job involving double-sided printing is completed. Alternatively, when the main power is turned on to the image forming apparatus 100, the control unit 1 determines that the check time has come. In the following description, the sheet length range currently targeted is referred to as a target sheet length range.

  In step S11, the control unit 1 extracts double-sided printing information 10 corresponding to the target paper length range. Then, based on the double-sided printing information 10 of the target paper length range, the control unit 1 can print without occurrence of an abnormality in double-sided printing for the nearest predetermined number of sheets using the paper P of the target paper length range. Recognize the number of times (hereinafter referred to as the normal number). At this time, the control unit 1 counts the number of pieces of first information included as printing result information in the double-sided printing information 10 of the target sheet length range, and recognizes the counted number as the number of times of normality.

  Thereafter, the process proceeds to step S12. The order of the processes in steps S11 and S12 is not particularly limited.

  When the process proceeds to step S12, the control unit 1 generates double-sided printing abnormality in double-sided printing for a predetermined number of sheets immediately using the sheet P of the target sheet length range based on the double-sided print information 10 of the target sheet length range. The number of times printing can not be performed (hereinafter referred to as an abnormal number) is recognized. At this time, the control unit 1 counts the number of pieces of second information included as printing result information in the double-sided printing information 10 of the target sheet length range, and recognizes the counted number as the number of abnormalities.

  After recognizing the number of normal times and the number of abnormal times, the process proceeds to step S13. In step S13, the control unit 1 obtains a value obtained by dividing the number of abnormal times by the total number of normal times and abnormal times as the incidence rate of double-sided printing abnormality (the incidence may be obtained as a percentage). The control unit 1 associates and holds the target sheet length range and the occurrence rate.

  For example, in double-sided printing for a predetermined number of sheets immediately before using sheet P of the target sheet length range, the number of times of normal discharge is two, the number of occurrences of double-sided printing abnormality is seven times, and common abnormality Assume that the number of occurrences is one. In this case, since the number of normal times is 2 and the number of abnormal times is 7, the incidence of double-sided printing abnormality is 0.78 (= 7 / (2 + 7)). For example, the control unit 1 rounds off the third decimal place of the value obtained by dividing the number of abnormalities by the total number.

  After calculating the incidence rate of the double-sided printing abnormality for each of the plurality of sheet length ranges, the control unit 1 performs an execution / non-execution determination process to determine whether or not the countermeasure process should be performed. The execution / non-execution determination process by the control unit 1 is performed for each of a plurality of sheet length ranges.

  Here, the first threshold, the second threshold, and the third threshold are stored in advance in the storage unit 5 as the threshold used in the execution / non-execution determination process by the control unit 1. The first threshold is the smallest value, the third threshold is the largest value, and the second threshold is a value between the first threshold and the second threshold. For example, the first threshold is 0.1 (10%), the second threshold is 0.5 (50%), and the third threshold is 0.9 (90%).

  The flow of the execution / non-execution determination process performed by the control unit 1 will be described below with reference to the flowchart shown in FIG. The flowchart illustrated in FIG. 5 starts when the control unit 1 ends the calculation of the incidence rate of double-sided printing abnormality. In the following description, the sheet length range currently targeted is referred to as a target sheet length range.

  In step S21, the control unit 1 recognizes the incidence rate of double-sided printing abnormality corresponding to the target sheet length, and determines whether the recognized double-sided printing abnormality incidence rate (Er) is equal to or greater than a first threshold (Th1). To judge. As a result, if the control unit 1 determines that the double-sided printing abnormality occurrence rate is equal to or more than the first threshold, the process proceeds to step S22.

  In step S22, the control unit 1 determines whether the double-sided printing abnormality occurrence rate (Er) is equal to or higher than a second threshold (Th2). As a result, when the control unit 1 determines that the double-sided printing abnormality occurrence rate is less than the second threshold, the process proceeds to step S23.

  If it transfers to step S23, the control part 1 will judge that countermeasure processing should be performed. In this case, the control unit 1 selects the first countermeasure process as the countermeasure process to be executed. That is, when the incidence rate of the double-sided printing abnormality is equal to or more than the first threshold and less than the second threshold, the control unit 1 executes the first countermeasure process. The first countermeasure process will be described later.

  If the control unit 1 determines in step S22 that the double-sided printing abnormality occurrence rate (Er) is equal to or higher than the second threshold (Th2), the process proceeds to step S24. In step S24, the control unit 1 determines whether the double-sided printing abnormality occurrence rate (Er) is equal to or higher than a third threshold (Th3). As a result, if the control unit 1 determines that the double-sided printing abnormality occurrence rate is less than the third threshold, the process proceeds to step S25.

  When the process proceeds to step S25, the control unit 1 determines that the countermeasure process should be performed. In this case, the control unit 1 selects the second countermeasure process as the countermeasure process to be executed. That is, when the incidence rate of the double-sided printing abnormality is equal to or more than the second threshold and less than the third threshold, the control unit 1 executes the second countermeasure process. The second countermeasure process will be described later.

  If the control unit 1 determines in step S24 that the double-sided printing abnormality occurrence rate (Er) is equal to or higher than the third threshold (Th3), the process proceeds to step S26. In step S26, the control unit 1 determines that the countermeasure process should be performed. In this case, the control unit 1 selects the third countermeasure process as the countermeasure process to be executed. The third countermeasure process will be described later.

  If the control unit 1 determines in step S21 that the double-sided printing abnormality occurrence rate (Er) is less than the first threshold (Th1), the process proceeds to step S27. When the process proceeds to step S27, the control unit 1 does not execute the countermeasure process.

  The control unit 1 causes the operation panel 4 to receive a reset instruction. For example, after the user or the maintenance contractor performs an operation (such as part replacement) for eliminating a double-sided printing abnormality, a reset instruction is issued to the operation panel 4.

  When operation panel 4 receives a reset instruction, control unit 1 performs reset processing for resetting double-sided printing information 10. When the reset process is performed by the control unit 1, all the print result information is deleted from the duplex printing information 10. Thereafter, the control unit 1 does not perform the abnormality occurrence rate calculation process until the predetermined number of double-sided printing using sheets P of any of the sheet length ranges among the plurality of sheet length ranges is reached. If the abnormality occurrence rate calculation process is not performed, the countermeasure process is not performed.

  When the incidence rate of double-sided printing abnormality in the target paper length range is equal to or more than the first threshold and less than the second threshold, the control unit 1 performs the first countermeasure process. As a first countermeasure process, the control unit 1 performs a notification process of notifying the user that the incidence rate of the double-sided printing abnormality in the target sheet length range is equal to or more than a first threshold. The notification is performed by the operation panel 4.

  The operation panel 4 displays a first notification screen 410 as shown in FIG. 6 to notify the user. On the first notification screen 410, a first message MG11 including the incidence rate of double-sided printing abnormality in the target paper length range is displayed. Further, on the first notification screen 410, a warning message MG12 is displayed. FIG. 6 illustrates the first notification screen 410 in the case where the incidence rate of double-sided printing abnormality in the first sheet length range (297 mm or more) is equal to or more than a first threshold.

  Here, when the incidence rate of double-sided printing abnormality in the target paper length range is equal to or more than the first threshold and less than the second threshold, the control unit 1 receives an instruction as to whether or not to prohibit double-sided printing. The operation panel 4 is operated. For example, operation panel 4 displays reception buttons B11 and B12 on first notification screen 410. When detecting a touch operation on the reception button B11, the control unit 1 determines that an instruction to prohibit the execution of double-sided printing is received from the user. On the other hand, when detecting a touch operation on the reception button B12, the control unit 1 determines that an instruction to prohibit the execution of double-sided printing is received from the user.

  When the control unit 1 receives an instruction to prohibit the execution of the double-sided printing, the control unit 1 performs a prohibition process for prohibiting the execution of the double-sided printing by the printing unit 3. When the prohibition process by the control unit 1 is performed, the operation panel 4 does not receive an instruction to execute double-sided printing. That is, the user can not instruct execution of double-sided printing.

  When the incidence rate of double-sided printing abnormality in the target paper length range is equal to or greater than the first threshold and less than the second threshold, the control unit 1 uses the communication unit 6 to transmit the target sheet length to the maintenance server 300. A notification process is performed to notify that the incidence rate of the double-sided printing abnormality in the printing range is equal to or higher than the first threshold. Thus, the current state of the image forming apparatus 100 can be recognized by the maintenance company.

  When the incidence rate of double-sided printing abnormality in the target paper length range is equal to or more than the second threshold and less than the third threshold, the control unit 1 performs the second countermeasure process. As the second countermeasure process, the control unit 1 performs a process of notifying the user that the incidence rate of the double-sided printing abnormality in the target paper length range is equal to or more than the second threshold. The notification is performed by the operation panel 4.

  The operation panel 4 displays a second notification screen 420 as shown in FIG. 7 to notify the user. On the second notification screen 420, a second message MG21 including the incidence of double-sided printing abnormality in the target paper length range is displayed. Further, on the second notification screen 420, a warning message MG22 is displayed. Note that FIG. 7 illustrates a second notification screen 420 in the case where the incidence rate of double-sided printing abnormality in the second sheet length range (210 mm or more and less than 297 mm) is equal to or more than a second threshold.

  Here, when the incidence rate of the double-sided printing abnormality in the target paper length range is equal to or more than the second threshold and less than the third threshold, the control unit 1 is the same as the case of being equal to or more than the first threshold and less than the second threshold. The operation panel 4 is made to receive an instruction as to whether or not to prohibit double-sided printing. That is, the operation panel 4 displays, on the second notification screen 420, a reception button B21 for receiving an instruction to prohibit the execution of double-sided printing and a reception button B22 for receiving an instruction not to prohibit the execution of double-sided printing. Then, when detecting the touch operation on the reception button B21, the control unit 1 performs a prohibition process for prohibiting the printing unit 3 from performing double-sided printing.

  The control unit 1 also performs notification processing when the incidence rate of double-sided printing abnormality in the target sheet length range is equal to or greater than the second threshold and less than the third threshold. In the notification process performed at this time, the maintenance server 300 is notified that the incidence rate of double-sided printing abnormality in the target paper length range is equal to or greater than the second threshold.

  If the incidence rate of double-sided printing abnormality in the target sheet length range is equal to or greater than the third threshold, the control unit 1 performs the third countermeasure process. As a third countermeasure process, the control unit 1 performs a process of notifying the user that the incidence rate of the double-sided printing abnormality in the target paper length range is equal to or more than the third threshold. The notification is performed by the operation panel 4.

  The operation panel 4 displays a third notification screen 430 as shown in FIG. 8 to notify the user. On the third notification screen 430, a third message MG31 including the incidence of double-sided printing abnormality in the target paper length range is displayed. FIG. 8 illustrates the third notification screen 430 in the case where the incidence rate of double-sided printing abnormality in the third sheet length range (less than 210 mm) is equal to or higher than the third threshold.

  Here, when the incidence rate of the double-sided printing abnormality in the target paper length range is equal to or higher than the third threshold, the control unit 1 forcibly (automatically) prohibits execution of the double-sided printing. Do. In this case, the control unit 1 causes the operation panel 4 to display a prohibition message MG32 for prohibiting the execution of double-sided printing.

  The control unit 1 also performs notification processing when the incidence rate of double-sided printing abnormality in the target paper length range is equal to or greater than the third threshold. In the notification process performed at this time, the maintenance server 300 is notified that the incidence rate of double-sided printing abnormality in the target paper length range is equal to or higher than the third threshold. Further, a maintenance request for requesting maintenance of the image forming apparatus 100 may be notified to the maintenance server 300.

  After prohibiting the execution of the double-sided printing, the control unit 1 causes the operation panel 4 to receive an instruction as to whether or not the prohibition of the double-sided printing is released. Then, when the operation panel 4 receives an instruction from the user for canceling the prohibition of double-sided printing, the control unit 1 cancels the prohibition of double-sided printing. This allows the user to issue an instruction to execute double-sided printing.

  However, in this case, when an abnormality in double-sided printing occurs until the number of sheets printed in double-sided printing reaches a predetermined threshold number of sheets after the execution of double-sided printing is prohibited, the control unit 1 prohibits the process again. I do. The threshold number of sheets is less than the predetermined number, for example, five.

  As described above, the image forming apparatus 100 according to the present embodiment, the printing unit 3 capable of executing single-sided printing and double-sided printing, the operation panel 4 (notifying unit) for notifying, and the nearest predetermined number (10) For minute double-sided printing, while recognizing the number of normal times that could be printed without occurrence of abnormality, recognize the number of abnormal times that could not be printed due to the occurrence of double-sided printing abnormality which is an abnormality that does not occur when performing single-sided printing An abnormality occurrence rate calculation process is performed in which the value obtained by dividing the number of times by the total number of normal times and abnormality times is calculated as the incidence rate of double-sided printing abnormality. And a control unit that causes the operation panel to perform notification of the incidence rate of double-sided printing abnormality.

  In the configuration of the present embodiment, the control unit 1 performs abnormality occurrence rate calculation processing for obtaining a value obtained by dividing the number of abnormalities by the total number of times of normality and the number of abnormalities as the incidence of double-sided printing abnormality. Here, the number of times of normal operation is the number of times of printing without occurrence of abnormality. The number of times of abnormality is the number of times printing can not be performed because a double-sided printing abnormality that is an abnormality that does not occur when single-sided printing is performed has occurred. That is, in the abnormality occurrence rate calculation process by the control unit 1, the number of times printing can not be performed because an abnormality that may occur even when single-sided printing is performed is not reflected. This makes it possible to accurately determine the incidence rate of double-sided printing abnormality.

  Further, the control unit 1 causes the operation panel 4 to notify the occurrence rate of the both-side printing abnormality when the occurrence rate of the both-side printing abnormality is equal to or more than a predetermined threshold. The user who has received the notification recognizes that double-sided printing abnormality is likely to occur. This makes it possible to prohibit only the execution of double-sided printing when double-sided printing abnormality is likely to occur (the execution of single-sided printing is not unnecessarily prohibited).

  Further, in the present embodiment, the control unit 1 obtains the incidence rate of double-sided printing abnormality for each of a plurality of predetermined paper length ranges, and the paper length range of which the incidence rate of double-sided printing abnormality becomes equal to or more than the threshold. The notification is given to the operation panel 4. In this configuration, the user who has received the notification can recognize the sheet length range in which the double-sided printing abnormality is likely to occur. Therefore, it is possible to prohibit only the execution of double-sided printing using the sheet P in the sheet length range in which double-sided printing abnormality is likely to occur.

  Further, in the present embodiment, when the double-sided printing abnormality occurrence rate is equal to or higher than the third threshold (maximum threshold), the control unit 1 automatically performs the prohibition process for prohibiting the execution of the double-sided printing. Here, if the incidence rate of double-sided printing abnormality is equal to or higher than the third threshold, there is a high possibility that double-sided printing abnormality will occur, so it is preferable to prohibit the execution of double-sided printing. However, some users may forget to perform an operation to prohibit double-sided printing. Therefore, in the configuration in which the prohibition process is automatically performed when the double-sided printing abnormality occurrence rate is equal to or higher than the third threshold, the convenience for the user is improved.

  Further, in the present embodiment, the control unit 1 prohibits the execution of double-sided printing when the incidence rate of double-sided printing abnormality is equal to or greater than the first threshold (minimum threshold) and less than the third threshold (maximum threshold). If the operation panel 4 receives an instruction to prohibit the execution of double-sided printing, the prohibition process is performed. In this configuration, the user can select whether to prohibit double-sided printing, thereby improving user convenience.

  Further, in the present embodiment, the control unit 1 causes the operation panel 4 to receive an instruction as to whether or not the execution inhibition of the double-sided printing is to be canceled, and instructs the operation panel 4 to cancel the inhibition of the double-sided printing execution. Cancels the prohibition of double-sided printing when accepted. In this configuration, it is possible for the user to select whether or not to cancel the execution of double-sided printing, thus improving user convenience.

  Further, in the present embodiment, when the double-sided printing abnormality occurs after the control unit 1 cancels the double-sided printing execution prohibition until the number of double-sided printed sheets reaches a predetermined threshold number, the prohibition process is performed. Do it automatically. In this configuration, although double-sided printing abnormality is likely to occur, it can be suppressed that the double-sided printing can be performed as it is.

  Further, in the present embodiment, when the incidence rate of the double-sided printing abnormality is equal to or more than the threshold value, the control unit 1 uses the communication unit 6 to the maintenance server 300 (server) to set the incidence rate of the double-sided printing abnormality to the threshold value. Notify that it is above. In this configuration, from the user's point of view, there is no need to perform the work of requesting maintenance from the maintenance company, which is convenient.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is indicated not by the description of the above embodiment but by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

1 control unit 3 printing unit 4 operation panel (notification unit)
30A main conveyance path 30B reverse conveyance path 100 image forming apparatus 300 maintenance server (server)
DP downstream position PP printing position UP upstream position

Claims (9)

A printing unit capable of performing single-sided printing and double-sided printing;
A notification unit that performs notification;
The double-sided printing for the most recent predetermined number of sheets recognizes the number of normal times that printing can be performed without occurrence of an abnormality, and the double-sided printing abnormality that is an abnormality that does not occur at the time of single-sided printing The occurrence rate is determined in advance by performing an abnormality occurrence rate calculation process of recognizing the number of occurrences and dividing the number of occurrences of abnormality by the total number of the number of occurrences of normality and the number of occurrences of occurrence as the occurrence rate of the double sided printing abnormality. An image forming apparatus comprising: a control unit that causes the notification unit to perform notification of the occurrence rate if the threshold value is exceeded. The printing unit includes a main conveyance path passing a printing position for printing an image on a sheet, a downstream position downstream of the printing position of the main conveyance path in the sheet conveyance direction, and the printing position of the main conveyance path Also includes a reverse conveyance path connecting the upstream position on the upstream side in the sheet conveyance direction, and when the double-sided printing is performed, the sheet fed to the main conveyance path is conveyed to the printing position, and one side at the printing position A single-sided printing sheet on which an image is printed is switched back and drawn from the downstream position to the reverse conveyance path, and the single-sided printing sheet is returned from the upstream position to the main conveyance path and conveyed to the printing position Yes,
The control unit causes an abnormality that occurs between the printing unit switching back the single-sided printing sheet and returning the single-sided printing sheet to a position downstream of the printing position of the main conveyance path in the sheet conveyance direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is detected as a double-sided printing abnormality.   The control unit obtains the incidence rate of the double-sided printing abnormality for each of a plurality of predetermined paper length ranges, and reports the paper length range in which the incidence rate of the double-sided printing abnormality becomes equal to or more than the threshold. The image forming apparatus according to claim 1, wherein the notification unit causes the notification unit to There are a plurality of threshold values,
The said control part performs the prohibition process for prohibiting execution of the said double-sided printing, when the incidence rate of the said double-sided printing abnormality is more than the said threshold value of the largest, It is characterized by the above-mentioned. An image forming apparatus according to claim 1. It has an operation panel that accepts instructions,
When the incidence rate of the double-sided printing abnormality is equal to or higher than the minimum threshold value and is less than the maximum threshold value, the control unit instructs the operation panel whether to prohibit execution of the double-sided printing. 5. The image forming apparatus according to claim 4, wherein the prohibition process is performed when the operation panel receives an instruction to prohibit execution of the double-sided printing. It has an operation panel that accepts instructions,
The control unit causes the operation panel to receive an instruction as to whether or not to cancel the execution inhibition of the double-sided printing, and when the operation panel receives an instruction to cancel the execution inhibition of the double-sided printing, the duplex operation is performed The image forming apparatus according to claim 4, wherein execution prohibition of printing is canceled.   The control unit performs the prohibition process when the double-sided printing abnormality occurs before the number of printed sheets of the double-sided printing reaches a predetermined threshold number of sheets after canceling the double-sided printing execution prohibition. The image forming apparatus according to claim 6, wherein It has an operation panel that accepts reset instructions,
8. The apparatus according to claim 1, wherein the control unit does not perform the abnormality occurrence rate calculation process until the number of printed sheets of the double-sided printing reaches the predetermined number after the operation panel receives the reset instruction. An image forming apparatus according to any one of the items. And a communication unit communicably connected to the server of the maintenance company,
The control unit notifies the server that the incidence rate of double-sided printing abnormality is equal to or more than the threshold value, using the communication unit, when the occurrence rate of the double-sided printing abnormality is equal to or more than the threshold value. The image forming apparatus according to any one of claims 1 to 8, wherein

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