JP2017107014A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an increase in time and effort for jam processing work.SOLUTION: An image forming apparatus comprises: a main conveyance path 2A; a paper feeding part 3; a conveyance part 9; a fixing part 6; an inverted conveyance path 2B; an inversion part 8 that performs switchback processing; and a control part that, when a jam error occurs, specifies in which of processing parts including the paper feeding part, conveyance part, fixing part, and inversion part the jam error occurs. When the jam error occurs, the control part does not cause the processing part where the jam error occurs to operate, and causes the processing parts other than the processing part where the jam error occurs to perform an ejection operation to eject sheets.SELECTED DRAWING: Figure 6

Description

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

  Some image forming apparatuses such as copiers and multifunction machines can execute a double-sided print job, which is a print job for printing an image on both sides of a sheet. Such an image forming apparatus is disclosed in Patent Document 1, for example.

  The image forming apparatus disclosed in Patent Document 1 includes a reversing unit and a reversing conveyance unit. In this image forming apparatus, when a double-sided print job is executed, first, the paper feed unit feeds paper to the main transport path and transports the paper along the main transport path. The image forming unit prints an image on one side. Thereafter, the reversing unit switches back the single-sided printing paper and supplies the switched back single-sided printing paper to the reverse conveyance path. The reverse conveyance unit conveys the single-sided printing paper supplied to the reverse conveyance path along the reverse conveyance path.

  The reverse conveyance path joins the main conveyance path at a position upstream of the image forming unit in the sheet conveyance direction. For this reason, the single-sided printing paper conveyed along the reverse conveying path returns to the main conveying path and enters the image forming unit again. At this time, since the front and back sides of the single-sided printing paper are reversed, an image is printed on the back side (unprinted side) of the single-sided printing paper.

JP 2007-93930 A

  In the image forming apparatus disclosed in Patent Document 1, if a jam error occurs during the execution of a double-sided print job, the user can use a sheet in order to simplify a jam processing operation (an operation for removing paper remaining in the image forming apparatus). The discharge operation is performed. Specifically, the reversing unit performs an operation of supplying paper to the reversing conveyance path or an operation of discharging the paper to the discharge unit. The reverse conveyance unit, the paper feeding unit, and the image forming unit perform an operation of conveying the paper in the same direction as the paper conveyance direction at the time of job execution. As a result, the paper remaining in the image forming apparatus is discharged to the discharge unit.

  Here, it is assumed that a jam error has occurred in the inverting unit. A jam error in the reversing portion occurs when a sheet in the middle of switchback is caught by a guide on the sheet conveyance path, etc., and the sheet stops traveling. For this reason, when a jam error occurs in the reversing unit, if the reversing unit performs a discharge operation, the paper may be damaged in the paper transport path (the paper may be bent or torn). Note that when a jam error occurs in a processing unit other than the reversing unit and the processing unit performs a discharging operation, the paper may be similarly damaged in the paper transport path.

  In this way, when the paper is damaged in the paper transport path, the paper is not discharged. In this case, the paper can be taken out by performing a jam processing operation. However, if the paper is damaged in the paper conveyance path, it becomes difficult to take out the paper, which causes a disadvantage that the time and labor of the jam processing work increase.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing an increase in the time and labor of a jam processing operation.

  In order to achieve the above object, an image forming apparatus of the present invention includes a paper discharge tray for discharging paper, a paper feed nip for feeding paper, a transfer nip for transferring an image to paper, and paper A main conveyance path that leads to a paper discharge tray via a fixing nip for fixing an image transferred to the paper, and a paper feeding rotator that forms a paper feeding nip. A sheet feeding unit that conveys the paper along the transfer path, and a transfer rotator that forms a transfer nip, a conveyance unit that transfers the image along the main conveyance path, and a fixing that forms the fixing nip. A fixing unit that includes a rotating body and fixes the image transferred onto the paper while transporting the paper along the main transport path; and a branch from the main transport path at a position downstream of the fixing nip in the paper transport direction. On the output tray On both sides of the sheet, and a reverse conveyance path including a first conveyance path, a second conveyance path branched from the first conveyance path and joined to the main conveyance path at a position upstream of the transfer nip in the sheet conveyance direction. When executing a double-sided print job, which is a print job for printing an image, the single-sided printed paper sent from the fixing unit is drawn into the first conveyance path, and the single-sided printed paper is temporarily moved in one direction toward the paper discharge tray. The single-sided printing paper is conveyed in the other direction opposite to the one direction at the timing when the trailing edge of the single-sided printing paper passes through the branch position between the first conveyance path and the second conveyance path. (2) a reversing unit that performs a switchback process for feeding into the conveyance path, a paper sensor for detecting the presence or absence of paper in a predetermined position on each of the main conveyance path and the reversal conveyance path, a paper feeding unit, and a conveyance Part A paper feeding unit that controls the operation of the printing unit and the reversing unit, detects whether a jam error has occurred based on the output value of the paper sensor, and is a processing unit that is responsible for transporting the paper when the jam error occurs A control unit that specifies which of the processing unit among the conveyance unit, the fixing unit, and the reversing unit has a jam error. Then, when a jam error occurs in any one of the paper feeding unit, the conveyance unit, the fixing unit, and the reversing unit, the control unit does not operate the processing unit in which the jam error has occurred, and the jam error has occurred. For the processing units other than the processing unit, a discharge operation for discharging the paper is performed.

  In the configuration of the present invention, when a jam error occurs, the processing unit in which the jam error has occurred is not operated, so that it is possible to prevent the sheet from being damaged in the main conveyance path or the conveyance path of the reverse conveyance path. In addition, when a jam error occurs, a processing unit other than the processing unit in which the jam error has occurred performs a discharging operation. Therefore, if paper remains in a processing unit other than the processing unit in which the jam error has occurred, Is discharged. As a result, it is possible to reduce the number of papers (papers to be removed) that are the target of the jam processing operation. As a result, it is possible to suppress an increase in the time and labor of the jam processing work, and the convenience for the user is improved.

  Further, when a jam error occurs, by causing a processing unit other than the processing unit in which the jam error has occurred to perform a discharge operation, the paper remaining in the processing unit other than the processing unit in which the jam error has occurred is discharged. Therefore, it is possible to suppress the occurrence of the inconvenience that the sheet is left in the image forming apparatus.

  With the configuration of the present invention, it is possible to suppress an increase in the time and labor of the jam processing work.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a sheet conveyance path of the image forming apparatus according to the embodiment of the present disclosure. 1 is a diagram illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a state of a sheet conveyance path when a jam occurs in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram illustrating a state of a sheet conveyance path when a jam occurs in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram for explaining a discharge operation performed when a jam occurs in the fixing unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram for explaining a discharge operation performed when a jam occurs in the fixing unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 9 is a diagram for explaining a discharge operation performed when a jam occurs in the conveyance unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 9 is a diagram for explaining a discharge operation performed when a jam occurs in the conveyance unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram for explaining a discharge operation performed when a jam occurs in the paper feeding unit in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram for explaining a discharge operation performed when a jam occurs in the reversing unit in the image forming apparatus according to the embodiment of the present disclosure. 7 is a flowchart for explaining a control flow when a jam occurs in the image forming apparatus according to the embodiment of the present disclosure. FIG. 6 is a diagram illustrating a state of a sheet conveyance path when a jam occurs in the image forming apparatus according to the embodiment of the present disclosure.

<< Configuration of Image Forming Apparatus >>
As shown in FIG. 1, the image forming apparatus 100 includes an image reading unit 1 and a printing unit 2. The image reading unit 1 reads a document and generates image data of the document. The printing unit 2 includes a paper feeding unit 3, an image forming unit 4, a transfer unit 5, and a fixing unit 6. Then, the printing unit 2 transports the paper P along the paper transport path 20, prints an image on the paper P being transported, and finally discharges the printed paper P to the paper discharge tray 20T.

  The paper feed unit 3 includes a pickup roller 31 and a paper feed roller pair 32. The paper feed roller pair 32 forms a paper feed nip PN for feeding the paper P to the paper transport path 20. That is, the paper feed roller pair 32 corresponds to a “paper feed rotator”. The paper feeding unit 3 pulls out the paper P from the paper cassette 30 and enters the paper feeding nip PN, and supplies the paper P to the paper transport path 20 (performs primary paper feeding).

  The image forming unit 4 is classified into mechanism units 40Bk, 40Y, 40C, and 40M corresponding to the respective colors of black (Bk), yellow (Y), cyan (C), and magenta (M). Each of the mechanism units 40Bk, 40Y, 40C, and 40M includes a photosensitive drum 41, a charging device 42, a developing device 43, and a cleaning device 44 so that the photosensitive drum 41 contacts the intermediate transfer belt 51 described later. Be placed. The image forming unit 4 includes an exposure device 45 that is used in common for each color. Then, the image forming unit 4 forms each color toner image on the surface of the corresponding photosensitive drum 41.

  The transfer unit 5 includes an intermediate transfer belt 51, a primary transfer roller 52, and a secondary transfer roller 53. The intermediate transfer belt 51 is stretched by a driving roller 54 and a driven roller 55. The primary transfer roller 52 is disposed inside the intermediate transfer belt 51 and sandwiches the intermediate transfer belt 51 with the photosensitive drum 41. The secondary transfer roller 53 is disposed so as to face the driving roller 54 with the intermediate transfer belt 51 interposed therebetween, and forms a transfer nip TN with the intermediate transfer belt 51. The transfer nip TN is a nip for transferring a toner image onto the paper P. That is, the intermediate transfer belt 51 and the secondary transfer roller 53 correspond to a “transfer rotator”. The transfer unit 5 primarily transfers the toner image formed by the image forming unit 4 onto the surface of the intermediate transfer belt 51 and then transfers the toner image 2 onto the sheet P while conveying the sheet P entering the transfer nip TN. Next transfer.

  The fixing unit 6 includes a fixing roller pair 61. One roller of the fixing roller pair 61 incorporates a heat source. The other roller is in pressure contact with the one roller, and forms a fixing nip FN with the one roller. The fixing nip FN is a nip for fixing the toner image transferred onto the paper P. That is, the fixing roller pair 61 corresponds to a “fixing rotating body”. The fixing unit 6 fixes the toner image on the paper P by heating and pressurizing the paper P that has entered the fixing nip FN while being conveyed.

  Here, the sheet conveying path 20 provided in the image forming apparatus 100 includes a main conveying path 2A and a reverse conveying path 2B as shown in FIG. In FIG. 2, the main conveyance path 2A is indicated by a solid line, and the reverse conveyance path 2B is indicated by a broken line.

  The main conveyance path 2A reaches the paper discharge tray 20T via the paper feed nip PN (paper feed unit 3), the transfer nip TN (transfer unit 5), and the fixing nip FN (fixing unit 6). When the print job is executed, the paper P fed to the main transport path 2A is transported through the paper feed nip PN, the transfer nip TN, and the fixing nip FN in this order. Hereinafter, a description will be given by adding a symbol D to the transport direction of the paper P at this time.

  The reverse conveyance path 2B is a conveyance path (conveyance path for conveying a single-sided printing paper P, which is a paper P on which an image is printed on one side) used during duplex printing. The reverse conveyance path 2 </ b> B has a first conveyance path 21 and a second conveyance path 22. In FIG. 2, the first transport path 21 and the second transport path 22 are indicated by different broken lines.

  The first transport path 21 branches from the main transport path 2A at a position downstream of the fixing nip FN in the transport direction D of the paper P and reaches the paper discharge tray 20T. The second conveyance path 22 branches from the first conveyance path 21 at a predetermined branch position P1, and at a predetermined merge position P2 (a position on the upstream side in the conveyance direction D of the paper P from the transfer nip TN). Merge into the main transport path 2A. Note that during double-sided printing, one side in a first direction D1 (corresponding to “one direction”) that is a direction toward the paper discharge tray 20T and a second direction D2 (corresponding to “other direction”) opposite to the first direction D1. The printing paper P is conveyed. Details will be described later.

  The paper transport path 20 is provided with a plurality of transport roller pairs 71 to 77 for transporting the paper P along the paper transport path 20.

  Between the paper feed nip PN and the transfer nip TN of the main transport path 2A, transport roller pairs 71 and 72 are provided in this order in the transport direction D of the paper P. Among these, the transport roller pair 72 located downstream in the transport direction D of the paper P temporarily stops the paper P that has reached the transport roller pair 72 and then sends the paper P to the transfer nip TN (secondary feeding). Do paper). Hereinafter, the conveyance roller pair 72 is referred to as a registration roller pair 72.

  A pair of transport rollers 73 is provided on the paper discharge tray 20T side of the main transport path 2A (the most downstream side in the transport direction D of the paper P). The transport roller pair 73 transports the paper P that has passed through the fixing nip FN along the main transport path 2A, and finally discharges the paper P to the paper discharge tray 20T. Hereinafter, the conveyance roller pair 73 is referred to as a discharge roller pair 73.

  A pair of transport rollers 74 is provided on the first transport path 21 on the paper discharge tray 20T side. As will be described in detail later, the transport roller pair 74 switches back the paper P at the time of duplex printing (reverses the traveling direction of the paper P). Hereinafter, the conveyance roller pair 74 is referred to as a reverse roller pair 74. Further, between the branch position P1 and the merge position P2 of the second transport path 22, transport roller pairs 75, 76, and 77 are provided in this order toward the second direction D2.

  A switching claw 78 for switching the transport path of the paper P is provided at a branch position between the main transport path 2A and the reverse transport path 2B (first transport path 21). The switching claw 78 is supported so as to be able to rotate. By rotating, the switching claw 78 blocks or opens the conveyance path from the main conveyance path 2A to the reverse conveyance path 2B. The reversing unit 8 is configured by the transport roller pair 74, the transport roller pair 75, and the switching claw 78.

  The paper transport path 20 is provided with a plurality of paper sensors PS (PS1 to PS6) for detecting the presence or absence of the paper P at a predetermined position on the transport path. Note that the paper sensor PS is an optical sensor that changes an output value according to the presence or absence of the paper P at a corresponding detection position, for example.

  The paper sensor PS1 is a sensor having a detection position in the vicinity of the installation position of the paper feed roller pair 32 (a position downstream of the paper feed nip PN in the transport direction D of the paper P). The paper sensor PS2 is a sensor having a detection position in the vicinity of the installation position of the transport roller pair 71 (a position on the upstream side in the transport direction D of the paper P from the installation position of the transport roller pair 71). The sheet sensor PS3 is a sensor having a detection position in the vicinity of the installation position of the registration roller pair 72 (a position upstream of the installation position of the registration roller pair 72 in the transport direction D of the paper P). The paper sensor PS4 is a sensor having a detection position in the vicinity of the installation position of the fixing roller pair 61 (a position on the downstream side in the conveyance direction D of the paper P from the fixing nip FN).

  The sheet sensor PS5 is a sensor having a detection position in the vicinity of the branch position P1 (downstream in the second direction D2 from the branch position P1). The sheet sensor PS6 is a sensor having a detection position in the vicinity of the installation position of the conveyance roller pair 77 (upstream in the second direction D2 from the installation position of the conveyance roller pair 77). Note that a paper sensor PS having a detection position near the installation position of the transport roller pair 76 may be provided.

  Returning to FIG. 1, the image forming apparatus 100 includes an operation panel 200. Operation panel 200 includes a touch panel display 201. The touch panel display 201 displays a screen for accepting various settings from the user. The operation panel 200 is provided with a plurality of hard keys 202. Examples of the hard keys 202 provided on the operation panel 200 include a start key for accepting a job execution instruction from the user and a numeric keypad for accepting numerical input from the user.

<< Hardware Configuration of Image Forming Apparatus >>
As shown in FIG. 3, the image forming apparatus 100 includes a control unit 110 that controls the entire apparatus. The control unit 110 includes a CPU 111 that executes various processes, a memory 112 that stores a control program for operating the CPU 111, and the like.

  The control unit 110 is connected to the image reading unit 1 and the printing unit 2 and controls the reading operation of the image reading unit 1 and the printing operation of the printing unit 2. The control unit 110 is connected to the operation panel 200 and controls the display operation of the operation panel 200 and detects an operation performed on the operation panel 200.

  Here, the control unit 110 controls the transport operation of a plurality of processing units (rotating bodies for transporting the paper P) responsible for transporting the paper P as control of the printing operation. That is, the control unit 110 controls driving of the motors M1, M2, M3, and M4 for causing each processing unit to perform a transport operation. Further, the control unit 110 controls on / off of the clutches C1, C2, and C3.

  The processing unit that performs the transport operation by the driving force of the motor M <b> 1 includes a pickup roller 31 and a paper feed roller pair 32. That is, the processing unit that performs the transport operation by the driving force of the motor M1 is the paper feeding unit 3. The pickup roller 31 and the paper feed roller pair 32 rotate by receiving the driving force of the motor M1, and feed (convey) the paper P.

  The pickup roller 31 is connected to the motor M1 via the clutch C1. Thereby, connection and cancellation | release of connection between the motor M1 and the pick-up roller 31 can be switched by controlling ON / OFF of the clutch C1. That is, only the paper feed roller pair 32 can be rotated.

  The processing unit that performs the transport operation by the driving force of the motor M2 includes an intermediate transfer belt 51, a secondary transfer roller 53, a drive roller 54, a transport roller pair 71, a registration roller pair 72, and transport roller pairs 76 and 77. In the following description, the processing unit that performs the transport operation by the driving force of the motor M2 is referred to as a transport unit 9. Each rotating body of the transport unit 9 rotates by receiving the driving force of the motor M2 and transports the paper P.

  The driving roller 54 rotates upon receiving the driving force of the motor M2. When the driving roller 54 rotates, the intermediate transfer belt 51 rotates, and the secondary transfer roller 53 rotates following the rotation of the intermediate transfer belt 51. Thereby, the paper P is conveyed.

  When the transport unit 9 performs an operation of transporting the paper P in the same direction as the transport direction D of the paper P when the job is executed, the transport roller pairs 76 and 77 rotate so that the paper P advances toward the merging position P2. When the transport unit 9 performs an operation of transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of executing the job, the paper P rotates so as to advance toward the branch position P1.

  The registration roller pair 72 is connected to the motor M2 through the clutch C2. Thereby, the connection and disconnection between the motor M2 and the registration roller pair 72 can be switched by controlling on / off of the clutch C2. That is, during the rotation of the transport roller pair 71, only the registration roller pair 72 can be rotated or the rotation can be stopped (secondary paper feeding can be performed at an appropriate timing).

  The processing unit that performs the conveying operation by the driving force of the motor M <b> 3 includes a fixing roller pair 61. That is, the processing unit that performs the transport operation by the driving force of the motor M3 is the fixing unit 6. The fixing roller pair 61 receives the driving force of the motor M3 and rotates to convey the paper P.

  The processing unit that performs the transport operation by the driving force of the motor M4 includes a reverse roller pair 74 and a transport roller pair 75. That is, the processing unit that performs the transport operation by the driving force of the motor M4 is the reversing unit 8. The reverse roller pair 74 and the transport roller pair 75 rotate by receiving the driving force of the motor M4 and transport the paper P.

  The discharge roller pair 73 is also configured to rotate by the driving force of the motor M4. In the case of this configuration, for example, the reverse roller pair 74 and the transport roller pair 75 are connected to the motor M4 via the clutch C3. Thereby, the connection and disconnection between the motor M4 and the reverse roller pair 74 (conveyance roller pair 75) can be switched by controlling on / off of the clutch C3. That is, only the discharge roller pair 73 can be rotated while the rotation of the reverse roller pair 74 (conveyance roller pair 75) is stopped. In addition, you may provide the motor for rotating the discharge roller pair 73 separately.

  Further, the control unit 110 detects the presence or absence of the paper P at the corresponding detection position based on the output values of the plurality of paper sensors PS in order to control the printing operation. In other words, the control unit 110 detects the arrival of the leading edge of the paper P and the passage of the trailing edge of the paper P at each detection position. For example, when executing a print job (including a double-sided print job), the control unit 110 determines whether or not a jam error has occurred based on the detection result. Details will be described later.

<< Single-sided printing and duplex printing >>
The conveyance path on the downstream side in the conveyance direction D of the paper P from the fixing nip FN varies depending on whether a single-sided print job or a double-sided print job is executed. Hereinafter, a specific description will be given with reference to FIG.

  First, when executing a single-sided print job, the control unit 110 discharges the single-sided printing paper P (paper P that has passed through the fixing nip FN) to the paper discharge tray 20T as it is. That is, the control unit 110 blocks the conveyance path from the main conveyance path 2 </ b> A to the reverse conveyance path 2 </ b> B by the switching claw 78. As a result, the single-sided printing paper P that has passed through the fixing nip FN is guided to the paper discharge tray 20T.

  When executing a duplex printing job, the control unit 110 uses the reversing unit 8 to perform switchback processing (processing to switch back the paper P). Specifically, the controller 110 opens the transport path from the main transport path 2A to the reverse transport path 2B by rotating the switching claw 78. As a result, the single-sided printing paper P that has passed through the fixing nip FN is drawn from the main transport path 2A to the reverse transport path 2B (first transport path 21).

  At this time, the control unit 110 rotates the pair of reverse rollers 74 so that the single-sided printing paper P drawn into the first transport path 21 proceeds in the first direction D1. And the control part 110 reversely rotates the inversion roller pair 74 at the timing when the rear end of the single-sided printing paper P passes the branch position P1. For example, when the control unit 110 detects the passage of the trailing edge of the single-sided printing paper P at the detection position of the paper sensor PS4, the control unit 110 starts measuring time, and after detecting the passage of the trailing edge of the single-sided printing paper P, a predetermined transport time When the time has elapsed, the reverse roller pair 74 is rotated in the reverse direction. As a result, the single-sided printing paper P travels in the second direction D2 and is fed into the second transport path 22.

  Thereafter, the control unit 110 continues to rotate the reverse roller pair 74 and the transport roller pair 75 as they are. As a result, the single-sided printing paper P sent to the second transport path 22 travels in the second transport path 22 in the second direction D2, and enters the main transport path 2A from the joining position P2 (returns to the main transport path 2A). ).

  The single-sided printing paper P that has returned to the main transport path 2A is transported along the main transport path 2A, so that it again passes through the transfer nip TN and the fixing nip FN in this order. At this time, since the front and back sides of the single-sided printing paper P are reversed, an image is printed on the back side (unprinted side) of the single-sided printing paper P. Then, the sheet P on which images are printed on both sides is conveyed as it is along the first conveyance path 2A and is discharged to the sheet discharge tray 20T.

<< Jam error occurrence detection >>
When executing a print job (including a double-sided print job), the control unit 110 detects the arrival of the leading edge of the paper P at a detection position of a certain paper sensor PS (referred to as a first sensor) among the plurality of paper sensors PS. Start timing from. Then, when a predetermined time has elapsed since the control unit 110 detects the arrival of the leading edge of the paper P at the detection position of the first sensor, the paper sensor PS ( It is confirmed whether or not the leading edge of the paper P has reached the detection position of the second sensor. As a result, if the arrival of the leading edge of the paper P cannot be confirmed, the control unit 110 determines that a jam error (paper jam in the paper transport path 20) has occurred. The predetermined time in this case is the time required for the paper P to travel between the detection position of the first sensor and the detection position of the second sensor, and the detection position of the first sensor and the detection position of the second sensor. Is a time that can be preliminarily calculated based on the distance between and the paper conveyance speed.

  Alternatively, the control unit 110 detects the trailing edge of the paper P at the detection position of a certain paper sensor PS among the plurality of paper sensors PS, and the rear end of the paper P at the same detection position even after a predetermined time has elapsed. If the passage cannot 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 paper P to pass through the same detection position after the leading edge of the paper P reaches the detection position of a certain paper sensor PS. It is a time that can be calculated in advance based on the length of the direction) and the sheet conveyance speed.

  When the control unit 110 detects that a jam error has occurred, the control unit 110 interrupts the print job being executed. Then, the control unit 110 causes the operation panel 200 to display an error message indicating that a jam error has occurred. That is, the control unit 110 notifies the user that a jam error has occurred (the operation panel 200 functions as a notification unit).

  In a jam processing operation performed by a user (operation for removing the jammed paper P, which is the jammed paper P), the side cover (not shown) of the image forming apparatus 100 is opened. When the side cover is opened, the sheet conveyance path 20 is exposed. As a result, the jammed paper P can be removed from the paper transport path 20. Alternatively, when the paper cassette 30 is pulled out from the image forming apparatus 100, the paper feeding unit 3 is exposed. Therefore, when the jammed paper P remains in the paper feeding unit 3, the jammed paper P can be removed by pulling out the paper cassette 30.

  After detecting the occurrence of a jam error, the control unit 110 determines whether or not the jam processing operation by the user has been completed. For example, when the control unit 110 detects that the side cover opened after the occurrence of the jam error is closed, the control unit 110 determines that the jam processing operation is finished. Further, when the control unit 110 detects that the paper cassette 30 pulled out after the occurrence of the jam error has been returned to its original state, the control unit 110 determines that the jam processing operation has been completed.

  When the jam processing operation is completed, the control unit 110 determines whether the paper P remains in the paper transport path 20 based on the output values of the plurality of paper sensors PS (whether the jammed paper P has been removed). Or). For example, if all the output values of the plurality of paper sensors PS are values indicating the absence of the paper P, the control unit 110 determines that the paper P does not remain in the paper transport path 20. If the paper P does not remain in the paper transport path 20, the control unit 110 resumes the print job that was interrupted when the occurrence of a jam error was detected. At this time, the control unit 110 stops displaying the error message.

  Note that if the paper P remains in the paper transport path 20, the control unit 110 does not resume the print job. In this case, the display of the error message is continued.

  Here, when the control unit 110 detects that a jam error has occurred, the processing unit among the paper feeding unit 3, the conveyance unit 9, the fixing unit 6, and the reversing unit 8 determines which jam error has occurred. Identify. Hereinafter, a specific description will be given with reference to FIG.

  First, a jam error in the reversing unit 8 will be described. For example, when the leading end of the paper P cannot be detected at the detection position of the paper sensor PS5 even after a predetermined time has elapsed since the rear end passage of the paper P is detected at the detection position of the paper sensor PS4, the control unit 110 detects the occurrence of a jam error. In this case, the control unit 110 determines that a jam error has occurred in the reversing unit 8. Note that the predetermined time here is that after the trailing edge of the paper P passes the paper sensor PS4, the leading edge of the paper P after the switchback (the trailing edge of the paper P before the switchback) reaches the paper sensor PS5. It takes time to complete.

  As another example, when the passage of the trailing edge of the paper P cannot be detected at the detection position of the paper sensor PS5 even after a predetermined time has passed since the front end of the paper P was detected at the detection position of the paper sensor PS5. (When a predetermined time has passed with the paper sensor PS5 outputting a value indicating the presence of the paper P), the control unit 110 detects the occurrence of a jam error. Also in this case, the control unit 110 determines that a jam error has occurred in the reversing unit 8.

  Next, a jam error in the fixing unit 6 will be described. For example, when the passage of the trailing edge of the paper P cannot be detected at the detection position of the paper sensor PS4 even after a predetermined time has elapsed since the arrival of the leading edge of the paper P at the detection position of the paper sensor PS4 (paper sensor). When a predetermined time has passed with PS4 outputting a value indicating the presence of paper P), control unit 110 detects the occurrence of a jam error. In this case, the control unit 110 determines that a jam error has occurred in the fixing unit 6.

  Next, a jam error in the transport unit 9 will be described. For example, when the passage of the trailing edge of the paper P cannot be detected at the detection position of the paper sensor PS3 even after a predetermined time has elapsed since the arrival of the leading edge of the paper P at the detection position of the paper sensor PS3 (paper sensor). When a predetermined time elapses while PS3 outputs a value indicating the presence of paper P), control unit 110 detects the occurrence of a jam error. In this case, the control unit 110 determines that a jam error has occurred in the transport unit 9. Note that the predetermined time here also takes into account the time for which the progress of the paper P is temporarily stopped.

  As another example, when the passage of the trailing edge of the paper P cannot be detected at the detection position of the paper sensor PS6 even after a predetermined time has elapsed since the front end of the paper P is detected at the detection position of the paper sensor PS6. (When a predetermined time has elapsed with the paper sensor PS6 outputting a value indicating the presence of the paper P), the control unit 110 detects the occurrence of a jam error. Also in this case, the control unit 110 determines that a jam error has occurred in the transport unit 9.

  Next, a jam error in the paper feeding unit 9 will be described. For example, when the passage of the trailing edge of the paper P cannot be detected at the detection position of the paper sensor PS1 even after a predetermined time has elapsed since the arrival of the leading edge of the paper P at the detection position of the paper sensor PS1 (paper sensor). When a predetermined time elapses while PS1 outputs a value indicating the presence of paper P), control unit 110 detects the occurrence of a jam error. In this case, the control unit 110 determines that a jam error has occurred in the paper feeding unit 3. Even when the leading edge of the paper P cannot be detected at the detection position of the paper sensor PS1 after the paper feeding by the paper feeding unit 3 is started, the control unit 110 causes the jamming (non-feed) in the paper feeding unit 3. Judge that paper jam has occurred.

<< Paper Ejection >>
In the present embodiment, the main transport path 2A and the reverse transport path 2B are used when executing a duplex printing job. Depending on the size (length in the transport direction) of the paper P to be printed, the main transport of another paper P while switching the paper P or transporting the paper P along the reverse transport path 2B. It is conveyed along the path 2A (see FIGS. 4 and 5).

  For example, it is assumed that a jam error occurs when the paper P exists at the position shown in FIGS. In this case, it is necessary to remove the paper P from the main transport path 2A and also remove the paper P from the reverse transport path 2B. However, depending on the user, only the removal operation of the paper P from one of the main conveyance paths 2A and the reverse conveyance path 2B may be performed, and the removal of the paper P from the other conveyance path may be forgotten. . Alternatively, the user may not be aware that the paper P remains on the other conveyance path.

  In the example illustrated in FIG. 4, the control unit 110 detects the end of the jam processing operation in a state where the paper P remains in the reversal conveyance path 2 </ b> B (a state where the paper P is removed from the main conveyance path 2 </ b> A). Suppose that At this time, the paper sensor PS5 outputs a value indicating the presence of the paper P. For this reason, even if the control unit 110 detects the end of the jam processing operation, the control unit 110 determines that the paper P remains in the paper transport path 20 and does not resume the interrupted print job (the operation panel 200 displays an error message). Continue to display). In this case, the jam processing operation must be performed again, which is troublesome for the user.

  In the example shown in FIG. 5, the control unit 110 detects the end of the jam processing operation in a state where the paper P remains in the reversal conveyance path 2B (a state where the paper P is removed from the main conveyance path 2A). Suppose that At this time, the output values of the plurality of paper sensors PS are values indicating the absence of the paper P. For this reason, the control unit 110 determines that the sheet P does not remain in the sheet conveyance path 20, and resumes the interrupted print job (the operation panel 200 stops displaying the error message). However, since the sheet P actually remains in the reverse conveyance path 2B, the sheet sensor PS6 immediately outputs a value indicating the absence of the sheet P after restarting the print job. That is, the output value of the paper sensor PS6 changes to a value indicating the absence of the paper P at an inappropriate timing. Therefore, the control unit 110 determines that a jam error has occurred and interrupts the print job. Also in this case, the jam processing operation must be performed again, which is troublesome for the user.

  For this reason, when the occurrence of a jam error is detected, the control unit 110 shifts to a discharge mode that is a mode for discharging the paper P remaining on the paper transport path 20. Then, the control unit 110 causes the printing unit 2 to perform an operation for discharging the paper P (hereinafter referred to as a discharge operation).

<First to third discharge modes>
When a jam error occurs in a processing unit other than the reversing unit 8, the control unit 110 shifts to one of the first to third discharge modes. In other words, when the jam error is not generated in the reversing unit 8, the paper P is discharged in any one of the first to third discharge modes.

  When shifting to any one of the first to third discharge modes, the control unit 110 causes the reversing unit 8 to perform a discharge operation. At this time, the reversing unit 8 performs an operation of transporting the paper P in the first direction D1 as a discharge operation. In addition, the control unit 110 causes the processing units other than the processing unit in which the jam error has occurred to perform the discharging operation. Note that the control unit 110 does not operate a processing unit in which a jam error has occurred.

  First, when the processing unit in which the jam error has occurred is the fixing unit 6, the control unit 110 shifts to the first discharge mode. When shifting to the first discharge mode, the control unit 110 causes the transport unit 9 and the sheet feeding unit 3 to perform a discharge operation without operating the fixing unit 6. At this time, the transport unit 9 and the paper feed unit 3 perform an operation of transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of job execution as a discharge operation. Note that the control unit 110 releases the connection between the pickup roller 31 and the motor M1 when the sheet feeding unit 3 performs the discharging operation. For this reason, only the paper feed roller pair 32 rotates when the paper feed unit 3 is performing a discharge operation.

  For example, it is assumed that a jam error occurs in the fixing unit 6 when the sheet P exists at the position shown in FIG. In this case, when the transport unit 9 performs a discharge operation (operation for transporting the paper P in the direction opposite to the transport direction D of the paper P during job execution), the paper P on the reverse transport path 2B is transported in the first direction D1. Then, it reaches the conveying roller pair 75 of the reversing unit 8. At this time, the reversing unit 8 performs a discharge operation (operation for transporting the paper P in the first direction D1). Accordingly, the paper P that has reached the pair of transport rollers 75 is transported in the first direction D1 as it is and is discharged to the paper discharge tray 20T.

  As another example, it is assumed that a jam error occurs in the fixing unit 6 when the sheet P exists at the position shown in FIG. In this case, when the transport unit 9 and the paper feed unit 3 perform a discharge operation (operation for transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of job execution), it exists on the downstream side of the main transport path 2A. The sheet P to be conveyed is conveyed in a direction opposite to the conveyance direction D of the sheet P at the time of executing the job, and reaches the sheet feeding nip PN. The paper P that has reached the paper feed nip PN is being ejected by the paper feed unit 3 (the operation of transporting the paper P in the direction opposite to the transport direction D of the paper P during job execution). At that time, the paper P is transported in a direction opposite to the transport direction D and returned (discharged) to the paper cassette 30.

  Next, when the processing unit in which the jam error has occurred is the transport unit 9, the control unit 110 shifts to the second discharge mode. When shifting to the second discharge mode, the control unit 110 causes the fixing unit 6 and the paper feed unit 3 to perform a discharge operation without operating the transport unit 9. At this time, the fixing unit 6 performs an operation of transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution as a discharge operation, and the paper feed unit 3 performs the transport direction D of the paper P at the time of job execution. The operation of conveying the paper P in the opposite direction is performed as a discharge operation (the connection between the pickup roller 31 and the motor M1 is released).

  For example, it is assumed that a jam error occurs in the transport unit 9 when the sheet P exists at the position shown in FIG. In this case, the fixing unit 6 performs a discharging operation (operation for transporting the paper P in the same direction as the transporting direction D of the paper P at the time of job execution), and the reversing unit 8 also performs a discharging operation (the first paper P is removed from the first direction). The sheet P in the fixing nip FN is discharged to the sheet discharge tray 20T. Although not shown, if the sheet P is present in the sheet feeding nip PN, the discharging operation by the sheet feeding unit 3 (operation for conveying the sheet P in the direction opposite to the conveying direction D of the sheet P during job execution). As a result, the paper P in the paper feed nip PN is returned to the paper cassette 30.

  If the processing unit in which the jam error has occurred is not the fixing unit 6, the control unit 110 rotates the discharge roller pair 73 so that the sheet P advances in the same direction as the conveyance direction D of the sheet P at the time of job execution. As a result, as shown in FIG. 9, when the paper P in the fixing nip FN has advanced toward the discharge tray 20T, the paper P can be discharged to the paper discharge tray 20T.

  Assume that a jam error has occurred in the fixing unit 6 in the state shown in FIG. In this case, if the discharge roller pair 73 is rotated without operating the fixing unit 6, there arises a disadvantage that the paper P in the fixing nip FN is torn. Therefore, when a jam error occurs in the fixing unit 6, the discharge roller pair 73 is not rotated.

  Next, when the processing unit in which the jam error has occurred is the sheet feeding unit 3, the control unit 110 shifts to the third discharge mode. When shifting to the third discharge mode, the control unit 110 causes the fixing unit 6 and the transport unit 9 to perform a discharge operation without operating the paper feed unit 3. At this time, the fixing unit 6 and the transport unit 9 perform an operation of transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution as a discharge operation. Further, the discharge roller pair 73 rotates so that the paper P advances in the same direction as the conveyance direction D of the paper P at the time of job execution.

  For example, it is assumed that a jam error occurs in the paper feeding unit 3 when the paper P exists at the position shown in FIG. In this case, the transport unit 9 is performing a discharge operation (operation for transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution), and the fixing unit 6 is also performing a discharge operation. The paper P in the transfer nip TN is transported in the same direction as the transport direction D of the paper P during job execution. At this time, if the transport path from the main transport path 2A to the reverse transport path 2B is open, the paper P that has passed through the fixing nip FN is discharged to the paper discharge tray 20T by the reversing unit 8. If the conveyance path from the main conveyance path 2A to the reverse conveyance path 2B is blocked, the sheet P that has passed through the fixing nip FN is discharged to the discharge tray 20T by the discharge roller pair 73.

<Fourth discharge mode>
When a jam error occurs in the reversing unit 8, the control unit 110 shifts to the fourth discharge mode. When shifting to the fourth discharge mode, the control unit 110 causes the fixing unit 6, the transport unit 9, and the paper feed unit 3 to perform a discharge operation without operating the reversing unit 8. Specifically, the control unit 110 causes the paper P to be transported in the same direction as the transport direction D of the paper P at the time of job execution as the discharge operation in the fourth discharge mode. When the fixing unit 6, the transport unit 9, and the paper feed unit 3 perform the discharge operation in the fourth discharge mode, the control unit 110 blocks the transport path from the main transport path 2 </ b> A to the reverse transport path 2 </ b> B. Further, the control unit 110 rotates the discharge roller pair 73 so that the paper P travels in the same direction as the transport direction D of the paper P at the time of job execution.

  For example, it is assumed that a jam error occurs in the reversing unit 8 when the paper P exists at the position shown in FIG. In this case, the transport unit 9 is performing a discharge operation (operation for transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution), and the fixing unit 6 is also performing a discharge operation. The paper P in the transfer nip TN is transported in the same direction as the transport direction D of the paper P during job execution. At this time, the conveyance path from the main conveyance path 2A to the reverse conveyance path 2B is blocked, and the discharge roller pair 73 rotates so that the sheet P advances in the same direction as the conveyance direction D of the sheet P at the time of job execution. Therefore, the paper P that has passed through the fixing nip FN is discharged to the paper discharge tray 20T. Although not shown, if the sheet P is present in the sheet feeding nip PN, the sheet feeding unit 3 performs a discharge operation (an operation for conveying the sheet P in the same direction as the sheet conveying direction D during job execution). The paper P in the paper feed nip PN is transported in the transport direction D of the paper P when the job is executed, and is finally discharged to the paper discharge tray 20T.

  Note that the operation of transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of executing the job may be performed by the paper feeding unit 3 as a discharge operation in the fourth discharge mode. In this case, the paper P in the paper feed nip PN is returned to the paper cassette 30. However, when the paper P exists so as to straddle the transport unit 9 and the paper feed unit 3, the operation of transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution is performed on the transport unit 9. Therefore, if the paper feeding unit 3 performs an operation of transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of executing the job, the paper P may be torn.

  Therefore, when the sheet P exists so as to straddle the conveying unit 9 and the sheet feeding unit 3, the operation of conveying the sheet P in the same direction as the conveying direction D of the sheet P at the time of executing the job is performed. It is preferable to cause both of the paper feeding units 3 to perform the process. For example, if the output values of the paper sensor PS1 and the paper sensor PS2 are values indicating the presence of the paper P, the control unit 110 indicates that the paper P exists across the transport unit 9 and the paper feeding unit 3. Judge that In other words, if the output value of the paper sensor PS1 is a value indicating the presence of the paper P and the output value of the paper sensor PS2 is a value indicating the absence of the paper P, the conveyance of the paper P at the time of job execution is performed. An operation of conveying the paper P in the direction opposite to the direction D may be performed by the paper feeding unit 3.

  If the print job is a single-sided print job, the conveyance path from the main conveyance path 2A to the reverse conveyance path 2B is blocked (the paper P is not supplied to the reverse conveyance path 2B). Therefore, if a jam error occurs during execution of a single-sided print job, the reversing unit 8 does not need to perform a discharge operation.

  The control flow when a jam error occurs during execution of a print job will be described below with reference to the flowchart shown in FIG. The flowchart shown in FIG. 12 starts when a jam error occurs during execution of a print job.

  In step S1, the control unit 110 interrupts the print job being executed. In step S2, the control unit 110 identifies a processing unit in which a jam error has occurred.

  In step S <b> 3, the control unit 110 determines whether the processing unit in which the jam error has occurred is the reversing unit 8. As a result, when the control unit 110 determines that a jam error has occurred in a processing unit other than the reversing unit 8, the process proceeds to step S4.

  In step S4, the control unit 110 determines whether the processing unit in which the jam error has occurred is the fixing unit 6. As a result, when the control unit 110 determines that a jam error has occurred in the fixing unit 6, the process proceeds to step S5. In step S5, the control unit 110 discharges the paper P in the first discharge mode.

  In step S4, when the control unit 110 determines that a jam error has occurred in a processing unit other than the fixing unit 6, the process proceeds to step S6. In step S6, the control unit 110 determines whether or not the processing unit in which the jam error has occurred is the transport unit 9. As a result, when the control unit 110 determines that a jam error has occurred in the transport unit 9, the process proceeds to step S7. In step S7, the control unit 110 discharges the paper P in the second discharge mode.

  In step S6, when the control unit 110 determines that the processing unit in which the jam error has occurred is not the transport unit 9, the process proceeds to step S8. In step S8, the control unit 110 discharges the paper P in the third discharge mode.

  In step S3, when the control unit 110 determines that a jam error has occurred in the reversing unit 8, the process proceeds to step S9. In step S9, the control unit 110 discharges the paper P in the fourth discharge mode.

  By the way, depending on the size (length in the transport direction) of the paper P to be printed, when a jam error occurs in the fixing unit 6, the leading edge of the paper P in the fixing nip FN is shown in FIG. May have been reached. At this time, if the reversing unit 8 performs the discharging operation (the operation of rotating the reversing roller pair 74 so that the paper P advances in the first direction D1) without operating the fixing unit 6, the paper P may be torn. . For this reason, when a jam error occurs in the fixing unit 6, the reversing unit 8 may not be operated, and only the conveying unit 9 and the sheet feeding unit 3 may perform the discharging operation. In this case, as the discharge operation, the transport unit 9 and the paper feed unit 3 are caused to transport the paper P in the direction opposite to the transport direction D of the paper P when the job is executed.

  In the present embodiment, as described above, when a jam error occurs, the processing unit in which the jam error has occurred is not operated. Thereby, it is possible to prevent the paper P from being damaged in the transport path of the paper transport path 20. In addition, when a jam error occurs, the processing unit other than the processing unit in which the jam error has occurred performs the discharging operation. Therefore, if the paper P remains in the processing unit other than the processing unit in which the jam error has occurred, The paper P is discharged to the paper discharge tray 20T (or the paper cassette 30). As a result, it is possible to reduce the number of papers P (papers P to be removed) that are the target of the jam handling operation. As a result, it is possible to suppress an increase in the time and labor of the jam processing work, and the convenience for the user is improved.

  Further, when a jam error occurs, by causing a processing unit other than the processing unit in which the jam error has occurred to perform a discharge operation, the paper P remaining in the processing unit other than the processing unit in which the jam error has occurred is discharged. Therefore, it is possible to suppress the occurrence of the inconvenience that the paper P is left in the paper conveyance path 20 while remaining.

  Further, in the present embodiment, when a jam error occurs in a processing unit other than the reversing unit 8, the reversing unit 8 performs a discharging operation. Thereby, when the paper P remains in the reversing unit 8, the paper P can be easily discharged to the paper discharge tray 20T.

  Further, in this embodiment, when a jam error occurs in the fixing unit 6, the operation of conveying the paper P in the direction opposite to the conveyance direction D of the paper P at the time of executing the job is set as the discharge operation, and the conveying unit 9 and the paper feeding unit 3 to do. As a result, when the paper P remains in the transport unit 9 or the paper feed unit 3, the paper P can be discharged (re-contained) into the paper cassette 30 without operating the fixing unit 6.

  Further, in the present embodiment, when a jam error occurs in the transport unit 9, the fixing unit 6 performs the operation of transporting the paper P in the same direction as the transport direction D of the paper P at the time of executing the job as a discharge operation. An operation for transporting the paper P in the direction opposite to the transport direction D of the paper P at the time of execution is performed by the paper feed unit 3 as a discharge operation. Thereby, when the paper P remains in the fixing unit 6, the paper P can be discharged to the paper discharge tray 20T without operating the transport unit 9. Further, when the paper P remains in the paper feeding unit 3, the paper P can be discharged (re-contained) into the paper cassette 30 without operating the transport unit 9.

  Further, in the present embodiment, when a jam error occurs in the paper feeding unit 3, the fixing unit 6 and the transport unit 9 are configured to discharge the operation of transporting the paper P in the same direction as the transport direction D of the paper P at the time of job execution. Let me do it. Thereby, when the paper P remains in the fixing unit 6 and the transport unit 9, the paper P can be discharged to the paper discharge tray 20T without operating the paper feed unit 3.

  Further, in the present embodiment, when a jam error occurs in the reversing unit 8, the conveyance path from the main conveyance path 2A to the reverse conveyance path 2B (first conveyance path 21) is blocked, and the sheet P is conveyed during job execution. An operation for conveying the paper P in the same direction as the direction D is caused to be performed by the fixing unit 6, the conveyance unit 9, and the paper feeding unit 3 as a discharge operation. As a result, when a jam error occurs in the reversing unit 8, the paper P conveyed by the fixing unit 6, the conveying unit 9, and the paper feeding unit 3 that performs the discharging operation enters the reverse conveying path 2B and is discharged. It is possible to suppress the occurrence of inconvenience that it is not performed.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the description of the above-described embodiment but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

2A Main transport path 2B Reverse transport path 3 Paper feed section 6 Fixing section 8 Reverse section 9 Transport section 20T Paper discharge tray 110 Control section

Claims (6)

A paper exit tray that ejects paper,
A paper feed nip for feeding paper, a transfer nip for transferring an image to the paper, and a main conveyance path to the paper discharge tray via a fixing nip for fixing the image transferred to the paper;
A paper feed rotator that forms the paper feed nip, and feeds paper to the main transport path and transports the paper along the main transport path;
A transfer unit that includes a transfer rotator that forms the transfer nip, and transfers an image onto a sheet while conveying the sheet along the main transfer path;
A fixing unit that includes a fixing rotator that forms the fixing nip, and fixes the image transferred onto the sheet while conveying the sheet along the main conveyance path;
A first conveyance path branched from the main conveyance path to the discharge tray at a position downstream of the fixing nip in the sheet conveyance direction, and a sheet conveyance direction branched from the first conveyance path and from the transfer nip. A reversing conveyance path including a second conveyance path that merges with the main conveyance path at an upstream position;
When a double-sided print job, which is a print job for printing an image on both sides of the paper, is executed, the single-sided printed paper sent from the fixing unit is drawn into the first conveyance path, and the single-sided printed paper is discharged. The paper is once transported in one direction toward the paper tray, and the one-sided printing paper is opposite to the one-way at a timing when the rear end of the one-sided printing paper passes through a branch position between the first transport path and the second transport path. A reversing unit that performs a switchback process for feeding the single-sided printing paper into the second transport path by transporting in the other direction;
A paper sensor for detecting the presence or absence of paper at a predetermined position on each conveyance path of the main conveyance path and the reverse conveyance path;
Controlling the operation of the paper feed unit, the transport unit, the fixing unit, and the reversing unit, and detecting whether or not a jam error has occurred based on the output value of the paper sensor. And a control unit for identifying which one of the processing unit among the sheet feeding unit, the conveyance unit, the fixing unit, and the reversing unit, which is a processing unit responsible for conveying the sheet, the jam error has occurred. ,
The control unit does not operate the processing unit in which the jam error has occurred when the jam error has occurred in any one of the paper feeding unit, the transport unit, the fixing unit, and the reversing unit, An image forming apparatus, wherein a processing unit other than the processing unit in which the jam error has occurred performs a discharge operation for discharging a sheet.   When the jam error occurs in the fixing unit, the control unit causes the reversing unit to perform an operation of conveying the paper in the one direction as the discharge operation, and also conveys the paper when the print job is executed. 2. The image forming apparatus according to claim 1, wherein an operation of conveying a sheet in a direction opposite to the direction is performed by the conveying unit and the sheet feeding unit as the discharging operation.   When the jam error occurs in the transport unit, the control unit causes the reversing unit to perform the operation of transporting the paper in the one direction as the discharge operation, and the transport direction of the paper when the print job is executed. An operation for conveying the paper in the same direction is performed by the fixing unit as the discharge operation, and an operation for conveying the paper in a direction opposite to the paper conveyance direction at the time of execution of the print job is set as the discharge operation. The image forming apparatus according to claim 1, wherein the image forming apparatus is performed.   The control unit causes the reversing unit to perform the operation of conveying the paper in the one direction as the discharge operation when the jam error occurs in the paper feeding unit, and the paper conveyance direction when the print job is executed. The image forming apparatus according to claim 1, wherein the fixing unit and the transport unit perform an operation of transporting a sheet in the same direction as the discharge operation as the discharge operation.   When the jam error occurs in the reversing unit, the control unit blocks a conveyance path from the main conveyance path to the first conveyance path, and is in the same direction as the sheet conveyance direction when the print job is executed. 5. The image forming apparatus according to claim 1, wherein an operation of conveying a sheet is performed by the fixing unit, the conveying unit, and the paper feeding unit as the discharging operation. 6. The transport unit includes a pair of transport rollers for supplying paper of the second transport path to the main transport path,
When the transport unit performs an operation of transporting the sheet in the same direction as the sheet transport direction when the print job is executed, the pair of transport rollers moves toward the joining position of the main transport path and the second transport path. When the sheet is rotated so that the sheet advances, and the conveyance unit performs an operation of conveying the sheet in a direction opposite to the sheet conveyance direction when the print job is executed, the first conveyance path, the second conveyance path, The image forming apparatus according to claim 1, wherein the image forming apparatus rotates so that the sheet advances toward the branch position.

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