Image forming apparatus and method for controlling image forming apparatus

Abstract

To reduce the time until resumption of printing.SOLUTION: An image forming apparatus comprises: an image forming unit that is provided on a conveyance path and forms a developer image on a medium; a fixing unit that is provided on the downstream side of the image forming unit in a medium conveyance direction on the conveyance path, and fixes the developer image to the medium; a control unit that controls warm-up of the fixing unit; and a medium detection unit that, when paper jam occurs, identifies a remaining position of a remaining medium remaining on the conveyance path and different from a jamming medium that is the cause of the paper jam. The control unit is configured to perform an ejection operation of ejecting the remaining medium after removal of the jamming medium, and before the ejection operation, determines whether to perform warm-up of the fixing unit on the basis of the remaining position of the remaining medium.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and a control method thereof.

Background Art

[0002] In an electrophotographic image forming apparatus, for example, when printing a plurality of pages, while conveying a plurality of media (e.g., printing paper) along a conveyance path at intervals, images are sequentially formed on each medium, and then, after the images are fixed on each medium by a fixing device, they are discharged. In a conventional image forming apparatus, when a jam (paper jam) is detected during such printing, the printing is once interrupted. Then, among the media remaining on the conveyance path other than the medium that caused the jam (hereinafter referred to as the jam medium) (hereinafter referred to as the remaining medium), the remaining media that can be discharged are automatically discharged, and then, the user is made to remove the jam medium and the remaining media that could not be discharged, and then the printing is resumed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional image forming apparatus, when a jam occurs, there is a possibility that a medium on which an image has been formed but not yet fixed remains as a remaining medium. Therefore, it is necessary to warm up the fixing device before automatically discharging the remaining medium, and there is a problem that the time until printing resumes when a jam occurs becomes long.

[0005] The present invention has been made in consideration of the above points, and proposes an image forming apparatus and a control method thereof that can shorten the time until printing resumes.

Means for Solving the Problem

[0006] The image forming apparatus of the present invention includes a conveyance unit that conveys a medium along a conveyance path, an image forming unit that is provided in the conveyance path and forms a developer image on the medium, a fixing unit that is provided on the downstream side of the image forming unit in the medium conveyance direction in the conveyance path and fixes the developer image on the medium, a control unit that controls the warm-up of the fixing unit, and a medium detection unit that specifies the residual position of residual media remaining in the conveyance path separately from the jammed media that caused the jam when a jam occurs on the conveyance path during printing in which the developer image is formed on the medium and fixed. The control unit is configured to perform a discharging operation of discharging the residual media by the conveyance unit after removing the jammed media, and further determines whether to perform the warm-up of the fixing unit based on the residual position of the residual media specified by the medium detection unit before the discharging operation.

[0007] The control method of the present invention is a control method for an image forming apparatus including a conveyance unit that conveys a medium along a conveyance path, an image forming unit that is provided in the conveyance path and forms a developer image on the medium, a fixing unit that is provided on the downstream side of the image forming unit in the medium conveyance direction in the conveyance path and fixes the developer image on the medium, a control unit that controls the warm-up of the fixing unit, and a medium detection unit that specifies the residual position of residual media remaining in the conveyance path separately from the jammed media that caused the jam when a jam occurs on the conveyance path during printing in which the developer image is formed on the medium and fixed. The control unit is configured to perform a discharging operation of discharging the residual media by the conveyance unit after removing the jammed media, and further determines whether to perform the warm-up of the fixing unit based on the residual position of the residual media specified by the medium detection unit before the discharging operation.

[0008] In this way, based on the residual position of the residual medium when jam occurs, by determining whether to perform warm-up of the fixing unit, for example, if the residual position of the residual medium is a position after developer fixing, it can be determined not to perform warm-up of the fixing unit and the time required for warm-up can be omitted.

Advantages of the Invention

[0009] According to the present invention, it is possible to realize an image forming apparatus and a control method for the image forming apparatus that can shorten the time until printing restart.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.

[0012] [1. First Embodiment] [1-1. Configuration of Image Forming Apparatus] FIG. 1 shows the configuration of the mechanism unit of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is an electrophotographic printer having a duplex printing function. This image forming apparatus 100 has a substantially box-shaped apparatus housing 20. Here, the right side in the figure of the apparatus housing 20 is the front side of the image forming apparatus 100, the left side in the figure is the rear side of the image forming apparatus 100, the front side in the figure is the left side of the image forming apparatus 100, the back side in the figure is the right side of the image forming apparatus 100, the upper side in the figure is the upper side of the image forming apparatus 100, and the lower side in the figure is the lower side of the image forming apparatus 100.

[0013] Inside the apparatus housing 20, there are provided a media feed tray 1, a media feed roller 2, a feed intermediate roller 3, a first registration roller 4, an entrance sensor 5, a second registration roller 6, a writing sensor 7, an image forming unit 8, a fixing unit 9, a discharge sensor 10, a discharge roller 11, a first conveyance roller 12, a second conveyance roller 13, and a main motor 14 which is a drive source for each roller and the photosensitive drum 22 described later.

[0014] The media paper feed tray 1 is provided at the lower part of the apparatus housing 20 and is adapted to store a plurality of media P. Further, a stacker 21 for discharging the media P is provided on the upper surface of the apparatus housing 20. Inside the apparatus housing 20, a main conveyance path R1 connecting the media paper feed tray 1 and the stacker 21 is provided. Along this main conveyance path R1, in order from the upstream side in the media conveyance direction (the side closer to the media paper feed tray 1), a media paper feed roller 2, a paper feed intermediate roller 3, a first registration roller 4, an entrance sensor 5, a second registration roller 6, a writing sensor 7, an image forming unit 8, a fixing unit 9, a discharge sensor 10, and a discharge roller 11 are provided.

[0015] In the image forming apparatus 100, at the time of single-sided printing, the media paper feed roller 2 feeds the media P one by one from the media paper feed tray 1 to the main conveyance path R1. The media P fed to the main conveyance path R1 is conveyed to the image forming unit 8 in a direction with the surface facing upward after the skew is corrected by the paper feed intermediate roller 3, the first registration roller 4, and the second registration roller 6.

[0016] The image forming unit 8 includes a photosensitive drum 22 and a transfer roller 23 that are arranged to face each other with the main conveyance path R1 therebetween. While conveying the media P with the media P sandwiched between the photosensitive drum 22 and the transfer roller 23, the developer image (image developed with the developer) formed on the photosensitive drum 22 is transferred to the surface of the media P by the transfer roller 23 to which a voltage of the opposite polarity to that of the developer is applied. The image forming unit 8 is configured to form (transfer) the developer image on the surface of the media P in this way.

[0017] The media P on which the developer image is formed is conveyed to the fixing unit 9. The fixing unit 9 includes a heating roller (which may be a belt) 24 and a pressure roller 25 that are arranged to face each other with the main conveyance path R1 therebetween. While conveying the media P with the media P sandwiched between the heating roller 24 and the pressure roller 25, the media P is heated and pressurized to fix the developer image formed on the media P to the media P. The media P on which the developer image is fixed is discharged to the stacker 21 by the discharge roller 11.

[0018] In the image forming apparatus 100, during single-sided printing, for example, when printing a plurality of pages, a plurality of (for example, up to two) media P are fed out at intervals on the main conveyance path R1, and images are sequentially formed on each media P.

[0019] The entrance sensor 5, the writing sensor 7, and the discharge sensor 10 are sensors that detect the media P at their respective detection positions. Note that no other media detection sensors are provided between the writing sensor 7 and the discharge sensor 10, and the distance between the writing sensor 7 and the discharge sensor 10 is longer than the length in the conveyance direction of the smallest size media P handled by the image forming apparatus 100. Also, in FIG. 1, the image forming unit 8 has a single-color configuration including a set of photoreceptor drums 22 and transfer rollers 23, but it may have a color configuration including a plurality of sets of photoreceptor drums 22 and transfer rollers 23.

[0020] Furthermore, inside the apparatus housing 20, a sub-conveyance path R2 is provided separately from the main conveyance path R1. The sub-conveyance path R2 connects a first point Pt1 between the discharge sensor 10 and the discharge roller 11 in the main conveyance path R1 (that is, on the downstream side in the media conveyance direction from the fixing unit 9) and a second point Pt2 between the paper feed intermediate roller 3 and the first registration roller 4 (that is, on the upstream side in the media conveyance direction from the image forming unit 8). This sub-conveyance path R2 is a conveyance path for turning over the media P that has passed through the fixing unit 9 and returning it to the upstream side of the image forming unit 8 in order to form an image on the back surface of the media P, and a first conveyance roller 12 and a second conveyance roller 13 are provided.

[0021] Here, the discharge sensor 10, which is an example of the first media detection sensor, is located between the fixing unit 9 and the first point Pt1 in the main conveyance path R1, and the entrance sensor 5, which is an example of the second media detection unit, is located between the second point Pt2 and the image forming unit 8 in the main conveyance path R1. Also, the writing sensor 7, which is an example of the third media detection unit, is located between the entrance sensor 5 and the image forming unit 8 in the main conveyance path R1. Furthermore, no media detection sensors are provided on the sub-conveyance path R2, and no media detection sensors are provided on the upstream side in the media conveyance direction from the entrance sensor 5 in the main conveyance path R1.

[0022] In the image forming apparatus 100, during double-sided printing, the medium P with the developer image fixed on its surface by the fixing device 9 is conveyed by the discharge roller 11 until the rear end passes through the first point Pt1. At the timing when the rear end of the medium P passes through the first point Pt1, the image forming apparatus 100 temporarily stops the rotation of the discharge roller 11 and reverses the rotation direction of the discharge roller 11 to convey the medium P in the reverse direction.

[0023] At this time, the medium P enters the sub-conveying path R2 from the first point Pt1, is conveyed by the first conveying roller 12 and the second conveying roller 13, and enters the main conveying path R1 again from the second point Pt2. Then, the medium P is conveyed to the image forming unit 8 with the back surface facing upward after the skew is corrected by the first registration roller 4 and the second registration roller 6, and a developer image is formed on the back surface by the image forming unit 8. After that, the medium P passes through the fixing device 9 and is discharged from the stacker 21.

[0024] Note that in the image forming apparatus 100, even during double-sided printing, for example, when printing a plurality of pages, a plurality of (for example, a maximum of two) media P are fed out at intervals on the conveying path composed of the main conveying path R1 and the sub-conveying path R2, and images are formed on each medium P in order. The configuration of the mechanism part of the image forming apparatus 100 is as described above.

[0025] Next, the configuration of the functional parts of the image forming apparatus 100 will be described with reference to the block diagram shown in FIG. 2. The image forming apparatus 100 includes a system control unit 101, a connection I / F unit 102, an image data storage unit 103, a print control unit 104, a medium feeding control unit 105, a medium conveyance control unit 106, an automatic discharge control unit 107, a fixing control unit 112, an operation / display unit 113, and a memory unit 114.

[0026] The connection I / F unit 102 receives a command from a host device (not shown) connected via a network such as a LAN, analyzes the command, and when the command is a print request command, notifies the system control unit 101 that a print request command has been received.

[0027] Upon receiving the notification that a print request command has been received, the system control unit 101 generates print image data based on the print information specified in the header of the print data received by the connection I / F unit 102 following the print request command, stores the image data in the image data storage unit 103, and instructs the print control unit 104 to start printing. Note that the print information includes information indicating single-sided printing or double-sided printing, information indicating the printing speed, information indicating the media type, etc. The system control unit 101 issues instructions to the print control unit 104 such as an instruction for single-sided printing or double-sided printing, an instruction for the printing speed, and an instruction for the set temperature of the fuser 9 according to the media type based on the print information.

[0028] The print control unit 104 that has received the instruction to start printing performs a printing operation together with the media paper feed control unit 105, the media conveyance control unit 106, and the fixing control unit 112. Specifically, the print control unit 104 controls the image forming operation by the image forming unit 8 based on the image data stored in the image data storage unit 103. The media paper feed control unit 105 controls the media paper feed operation by the media paper feed roller 2. The media conveyance control unit 106 controls the media conveyance operation by the paper feed intermediate roller 3, the first registration roller 4, the second registration roller 6, the discharge roller 11, the first conveyance roller 12, and the second conveyance roller 13. The fixing control unit 112 controls the fixing operation by the fuser 9.

[0029] Also, the system control unit 101 uses the printing information extracted from the header of the print data (i.e., information indicating single-sided printing or double-sided printing) and the detection results of each sensor (the entrance sensor 5, the writing sensor 7, the discharge sensor 10) to detect the occurrence of a jam (paper jam) and identify the occurrence position. Further, the system control unit 101 uses the printing information and the detection results of each sensor to identify the remaining position of the medium (i.e., the remaining medium) P remaining on the main conveyance path R1 and the sub-conveyance path R2, apart from the medium (i.e., the jam medium) P that caused the jam at the time of jam occurrence. Then, the system control unit 101 notifies the automatic discharge control unit 107 of the fact that a jam has occurred, the jam occurrence position, and the remaining position of the remaining medium P.

[0030] Furthermore, when the system control unit 101 detects the occurrence of a jam, it displays, on the operation and display unit 113 that functions as an operation unit and a display unit, a message indicating that a jam has occurred and a message prompting the removal of the jam medium, and stores the printing information extracted from the print data in the jam detection-time printing information storage unit 117 provided in the memory unit 114. In addition, when the occurrence of a jam is detected, the system control unit 101 may display, on the operation and display unit 113, a message or an image indicating the jam occurrence position in addition to the above-described messages.

[0031] When the automatic discharge control unit 107 receives a notification from the system control unit 101 that a jam has occurred, it determines whether to execute the automatic discharge of the remaining medium P based on the printing information stored in the jam detection-time printing information storage unit 117, the jam occurrence position, and the remaining position of the remaining medium P, and if it determines to perform the operation, it performs the automatic discharge of the remaining medium P.

[0032] Specifically, the automatic discharge control unit 107 includes an automatic discharge execution determination unit 108, a main conveyance path automatic discharge control unit 109, a warm-up (hereinafter abbreviated as W.U) control unit 110, and a sub-conveyance path automatic discharge control unit 111.

[0033] When a jam occurs, the automatic discharge execution determination unit 108 determines whether to execute the automatic discharge of the remaining medium P based on the print information, the jam occurrence position, and the remaining position of the remaining medium P. Here, for example, when the remaining medium P remains on the main conveyance path R1 during single-sided printing, the automatic discharge execution determination unit 108 determines to execute the automatic discharge of the remaining medium P, and rewrites the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 provided in the memory unit 114 from not executing the automatic discharge to executing the automatic discharge.

[0034] Also, for example, when the remaining medium P remains on the sub-conveyance path R2 during double-sided printing, the automatic discharge execution determination unit 108 determines to execute the automatic discharge of the remaining medium P, and rewrites the content of the sub-conveyance path automatic discharge execution information stored in the sub-conveyance path automatic discharge execution information storage unit 116 provided in the memory unit 114 from not executing the automatic discharge to executing the automatic discharge.

[0035] When the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 indicates that the automatic discharge is to be executed, the main conveyance path automatic discharge control unit 109 causes the W.U control unit 110 to execute the warm-up of the fuser 9, and then executes the automatic discharge of the remaining medium P remaining on the main conveyance path R1. Note that the operation of automatically discharging the remaining medium P remaining on the main conveyance path R1 is an operation of conveying the remaining medium P along the main conveyance path R1 and discharging it from the main conveyance path R1 to the stacker 21. Hereinafter, this operation is also referred to as the main conveyance path automatic discharge operation.

[0036] When the sub-conveyor automatic discharge control unit 111 determines that the sub-conveyor automatic discharge execution information stored in the sub-conveyor automatic discharge execution information storage unit 116 indicates that automatic discharge is to be executed, it performs automatic discharge of the residual medium P remaining in the sub-conveyor path R2. Note that the operation of automatically discharging the residual medium P remaining in the sub-conveyor path R2 is an operation of conveying the residual medium P from the sub-conveyor path R2 to the main conveyor path R1 and discharging it from the main conveyor path R1 to the stacker 21. Hereinafter, this operation is also referred to as the sub-conveyor automatic discharge operation. In the image forming apparatus 100, during the main conveyor automatic discharge operation and the sub-conveyor automatic discharge operation, the transfer of the developer image to the residual medium P to be automatically discharged is not performed. The configuration of the functional units of the image forming apparatus 100 is as described above.

[0037] [1-2. Operations of the Image Forming Apparatus] Next, the operations of the image forming apparatus 100 will be described. Here, as the operations of the image forming apparatus 100, the operations at the time of jam occurrence will be described using the flowchart shown in FIG. 3. Note that this operation is mainly performed by the system control unit 101 and the automatic discharge control unit 107. As shown in FIG. 3, after causing the print control unit 104 to start printing in step SP301, the system control unit 101 detects a jam in the subsequent step SP302.

[0038] At this time, assume that the image forming apparatus 100 is in the state shown in FIG. 4, for example. That is, when performing single-sided printing, it is assumed that the leading end portion of the medium P1 forms a bellows shape in front of the discharge roller 11, causing a jam, and the subsequent medium P2 has reached in front of the fixing device 9. In this case, after the medium P1 reaches the detection position of the discharge sensor 10 and the discharge sensor 10 is turned on, the system control unit 101 detects the occurrence of a jam because the discharge sensor 10 does not turn off even after a predetermined time has elapsed. Also at this time, the system control unit 101 specifies that a jam has occurred at the detection position of the discharge sensor 10 on the main conveyance path R1. Further at this time, since the medium P2 has passed through the detection position of the write sensor 7 and the write sensor 7 is off, the system control unit 101 specifies that the medium P2 remains as a residual medium between the write sensor 7 and the discharge sensor 10 on the main conveyance path R1.

[0039] In addition, not only the detection results of each sensor but also the elapsed time since the detection results changed may be used to more accurately specify the residual position of the medium P2.

[0040] On the other hand, assume that the image forming apparatus 100 is in the state shown in FIG. 5, for example. That is, when performing double-sided printing, it is assumed that the medium P3 on which printing on the front surface has been completed forms a bellows shape in front of the fixing device 9, causing a jam, and the subsequent medium P4 is located on the sub-conveyance path R2. In this case, after the medium P3 passes through the detection position of the write sensor 7 and the write sensor 7 turns off from on, the system control unit 101 detects the occurrence of a jam because the discharge sensor 10 does not turn on even after a predetermined time has elapsed. Also at this time, the system control unit 101 specifies that a jam has occurred between the write sensor 7 and the discharge sensor 10 on the main conveyance path R1. Further at this time, since the medium P4 has passed through the detection position of the discharge sensor 10 and the discharge sensor 10 is off, and the entrance sensor 5 is not yet on, the system control unit 101 specifies that the medium P4 remains as a residual medium on the sub-conveyance path R2.

[0041] In the image forming apparatus 100, after the medium P4 passes through the discharge sensor 10, the rotation direction of the discharge roller 11 is switched to the reverse direction, so that the medium P4 is conveyed to the sub-conveying path R2. Therefore, not only the detection result of the discharge sensor 10 but also the elapsed time after the rotation direction of the discharge roller 11 is switched to the reverse direction may be used to more accurately specify the residual position of the medium P4.

[0042] The system control unit 101 that has detected the jam as described above stops the main motor 14 to interrupt printing, and notifies the automatic discharge control unit 107 of the printing information at this time, the occurrence position of the jam, and the position of the residual medium P (the medium P2 shown in FIG. 3 and the medium P4 shown in FIG. 4).

[0043] In the subsequent step SP303, the automatic discharge control unit 107 determines whether to execute automatic discharge of the residual medium P by the automatic discharge execution determination unit 108.

[0044] Here, if the image forming apparatus 100 at this time is in the state shown in FIG. 4, for example, that is, a jam occurs during single-sided printing and the residual medium P (for example, the medium P2 shown in FIG. 4) remains on the main conveyance path R1, the automatic discharge execution determination unit 108 determines to execute automatic discharge of the residual medium P on the main conveyance path R1, and as shown in FIG. 8(A), the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 is rewritten to indicate that automatic discharge is to be executed.

[0045] On the other hand, if the image forming apparatus 100 at this time is in the state shown in FIG. 5, for example, that is, a jam occurs during double-sided printing and the residual medium P (for example, the medium P4 shown in FIG. 5) remains on the sub-conveyance path R2, the automatic discharge execution determination unit 108 determines to execute automatic discharge of the residual medium P on the sub-conveyance path R2, and as shown in FIG. 8(C), the content of the sub-conveyance path automatic discharge execution information stored in the sub-conveyance path automatic discharge execution information storage unit 116 is rewritten to indicate that automatic discharge is to be executed. Here, it is assumed that one of the main conveyance path automatic discharge execution information and the sub-conveyance path automatic discharge execution information is rewritten to indicate that automatic discharge is to be executed.

[0046] In the subsequent step SP304, the system control unit 101 displays, on the operation and display unit 113, a message indicating that a jam has occurred and a message prompting to remove the jammed medium P. The user who has confirmed the message displayed on the operation and display unit 113 removes the jammed medium P from the image forming apparatus 100.

[0047] Here, for example, when the medium P1, which is a jammed medium, is removed from the image forming apparatus 100 in the state shown in FIG. 4, the image forming apparatus 100 assumes the state shown in FIG. 6, for example. That is, at this time, the image forming apparatus 100 is in a state where the medium P2 remains between the writing sensor 7 and the discharge sensor 10 on the main conveyance path R1.

[0048] On the other hand, for example, when the medium P3, which is a jammed medium, is removed from the image forming apparatus 100 in the state shown in FIG. 5, the image forming apparatus 100 assumes the state shown in FIG. 7, for example. That is, at this time, the image forming apparatus 100 is in a state where the medium P4 remains on the sub-conveyance path R2.

[0049] In the subsequent step SP305, the system control unit 101 starts an initial operation to perform recovery printing (that is, to resume the interrupted printing). The initial operation is a preliminary operation for checking whether each part of the image forming apparatus 100 operates normally. Also at this time, when either or both of the entrance sensor 5 and the writing sensor 7 are on, the system control unit 101 displays, on the operation and display unit 113, a message prompting the user to remove the medium P that is turning on either or both of the entrance sensor 5 and the writing sensor 7, so as to cause the user to remove the medium P.

[0050] When starting the initial operation, in step SP306, the automatic discharge control unit 107 determines, by the automatic discharge execution presence / absence determination unit 108, whether the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 indicates that automatic discharge is to be executed.

[0051] Here, when the main conveyance path automatic discharge execution information indicates that automatic discharge is to be executed, this means that automatic discharge of the main conveyance path R1 is to be executed. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP306 by the automatic discharge execution determination unit 108 and moves to step SP307.

[0052] In step SP307, since the residual medium P on the main conveyance path R1 has a developer image attached (that is, the developer image has been transferred) and there is a possibility of non-fixing, the automatic discharge control unit 107 determines that in order to fix the developer image on the residual medium P, the fuser 9 is to be warmed up, and the fuser 9 is warmed up by the W.U. control unit 110 based on the set temperature at the time of printing before the jam (that is, the set temperature corresponding to the medium type indicated in the print information).

[0053] In the subsequent step SP308, the automatic discharge control unit 107 starts the main conveyance path automatic discharge operation. At this time, the automatic discharge control unit 107 operates the main motor 14 by the main conveyance path automatic discharge control unit 109, starts the conveyance of the residual medium P on the main conveyance path R1 at a conveyance speed matching the printing speed at the time of printing before the jam (that is, the printing speed indicated in the print information), and starts the detection of the residual medium P by each sensor, then moves to step SP309.

[0054] On the other hand, when the main conveyance path automatic discharge execution information indicates that automatic discharge is not to be executed, this means that the main conveyance path automatic discharge operation is not to be executed. In this case, the automatic discharge control unit 107 obtains a negative result in step SP306 by the automatic discharge execution determination unit 108, skips steps SP307 and SP308, and moves to step SP309.

[0055] In step SP309, the automatic discharge control unit 107 determines whether the sub-conveyance path automatic discharge execution information stored in the sub-conveyance path automatic discharge execution information storage unit 116 by the automatic discharge execution determination unit 108 indicates that automatic discharge is to be executed.

[0056] Here, when the sub-conveyor automatic discharge execution information indicates that automatic discharge is to be executed, this means that the sub-conveyor automatic discharge operation is to be performed. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP309 by the automatic discharge execution determination unit 108 and moves to step SP310.

[0057] In step SP310, since the residual medium P on the sub-conveyor R2 has a developed image that has been fixed, the automatic discharge control unit 107 determines that the warm-up of the fuser 9 is not performed and immediately starts the sub-conveyor automatic discharge operation. At this time, the automatic discharge control unit 107 operates the main motor 14 by the sub-conveyor automatic discharge control unit 111, starts conveying the residual medium P on the sub-conveyor R2 at a conveying speed corresponding to the printing speed during printing, and causes each sensor to start detecting the residual medium P by the system control unit 101, and then moves to step SP311.

[0058] On the other hand, when the sub-conveyor automatic discharge execution information indicates that automatic discharge is not to be executed, this means that the sub-conveyor automatic discharge operation is not to be performed. In this case, the automatic discharge control unit 107 obtains a negative result in step SP309 by the automatic discharge execution determination unit 108, skips step SP310, and moves to step SP311.

[0059] In step SP311, when the main-conveyor automatic discharge execution information indicates that automatic discharge is to be executed, the automatic discharge control unit 107 determines whether the discharge sensor 10 is turned on while operating the main motor 14 for a predetermined time. The predetermined time at this time is set to the longest time required for the residual medium P remaining on the main-conveyor R1 to reach the discharge sensor 10. For example, as shown in FIG. 6, when the residual medium P (medium P2) on the main-conveyor R1 is located between the write sensor 7 and the discharge sensor 10, the time obtained by dividing the distance obtained by subtracting the length in the conveying direction of the residual medium P from the distance between the write sensor 7 and the discharge sensor 10 by the conveying speed of the residual medium P may be set as the predetermined time.

[0060] Here, when the discharge sensor 10 is turned on within a predetermined time, this means that the residual medium P has reached the discharge sensor 10. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP311 and proceeds to step SP312. In step SP312, the automatic discharge control unit 107 continues the main conveyance path automatic discharge operation and conveys the residual medium P on the main conveyance path R1 toward the stacker 21, and then proceeds to the next step SP313.

[0061] On the other hand, when the discharge sensor 10 is not turned on within a predetermined time, this means that it is highly likely that the user has removed the residual medium P together with the jammed medium P. In this case, the automatic discharge control unit 107 obtains a negative result in step SP311, skips step SP312, and proceeds to step SP313. Also, when the main conveyance path automatic discharge execution information indicates that automatic discharge is not to be performed, the automatic discharge control unit 107 obtains a negative result in step SP311 and proceeds to step SP313.

[0062] Here, when the automatic discharge control unit 107 continues the main conveyance path automatic discharge operation in step SP312, at the timing after the residual medium P on the main conveyance path R1 has passed the detection position of the discharge sensor 10 and has been discharged to the stacker 21, the main conveyance path automatic discharge operation is terminated, and the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 is rewritten to indicate that automatic discharge is not to be performed. Also, when the discharge sensor 10 is not turned on within a predetermined time, the automatic discharge control unit 107 terminates the main conveyance path automatic discharge operation and rewrites the content of the main conveyance path automatic discharge execution information to indicate that automatic discharge is not to be performed.

[0063] In step SP313, when the sub-conveyor automatic discharge execution information is stored in the sub-conveyor automatic discharge execution information storage unit 116, the automatic discharge control unit 107 determines whether the inlet sensor 5 is turned on while operating the main motor 14 for a predetermined time. The predetermined time at this time is set to the longest time required for the residual medium P remaining on the sub-conveyor R2 to reach the inlet sensor 5. For example, the predetermined time may be obtained by dividing the distance between the tip of the medium P (the tip closer to the first point Pt1) and the inlet sensor 5 when the discharge roller 11 is once stopped and rotated reversely by the conveyance speed of the residual medium P.

[0064] Here, if the inlet sensor 5 is turned on within the predetermined time, this means that the residual medium P has reached the inlet sensor 5. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP313 and proceeds to step SP314. In step SP314, the automatic discharge control unit 107 continues the sub-conveyor automatic discharge operation and conveys the residual medium P on the sub-conveyor R2 toward the stacker 21, and then proceeds to the next step SP315.

[0065] On the other hand, if the inlet sensor 5 is not turned on within the predetermined time, this means that it is highly likely that the user has removed the residual medium P together with the jammed medium P. In this case, the automatic discharge control unit 107 obtains a negative result in step SP313, skips step SP314, and proceeds to step SP315. Also, when the sub-conveyor automatic discharge execution information indicates that automatic discharge is not to be performed, the automatic discharge control unit 107 obtains a negative result in step SP313 and proceeds to step SP315.

[0066] Here, when the automatic discharge control unit 107 continues the sub-conveyor path automatic discharge operation in step SP314, at the timing after the residual medium P on the sub-conveyor path R2 passes through the detection position of the discharge sensor 10 and is discharged to the stacker 21, the sub-conveyor path automatic discharge operation is terminated, and the content of the sub-conveyor path automatic discharge execution information stored in the sub-conveyor path automatic discharge execution information storage unit 116 is rewritten to indicate that automatic discharge is not to be executed. Also, when the entrance sensor 5 does not turn on within a predetermined time, the automatic discharge control unit 107 also terminates the sub-conveyor path automatic discharge operation and rewrites the content of the sub-conveyor path automatic discharge execution information to indicate that automatic discharge is not to be executed.

[0067] In step SP315, the automatic discharge control unit 107 waits until all the started automatic discharge operations are completed. Then, when all the started automatic discharge operations are completed, the automatic discharge control unit 107 obtains an affirmative result in this step SP315 and moves to step SP316.

[0068] In step SP316, when the automatic discharge operation is completed, the system control unit 101 performs process operations such as current measurement of the image forming unit 8 and developer disposal.

[0069] In step SP317, the system control unit 101 terminates the initial operation. In the subsequent step SP318, a recovery print is performed to resume the printing interrupted by jam detection and perform the remaining printing. In the subsequent step SP319, the system control unit 101 terminates a series of printing. The operation of the image forming apparatus 100 when a jam occurs is as described above.

[0070] [1-3. Summary and effects] As described above, in the first embodiment, the image forming apparatus 100 includes rollers (media supply roller 2, intermediate paper feed roller 3, first registration roller 4, second registration roller 6, discharge roller 11, first conveyance roller 12, second conveyance roller 13, pressure roller 25) and a photosensitive drum 22 as a conveyance unit that conveys the medium P along the main conveyance path R1 and the sub-conveyance path R2, which are examples of a conveyance path; an image forming unit 8 provided on the main conveyance path R1 that forms a developer image on the medium P; a fixing device 9, which is an example of a fixing unit, provided on the downstream side in the medium conveyance direction from the image forming unit 8 in the main conveyance path R1 that fixes the developer image on the medium P; an automatic discharge control unit 107, which is an example of a control unit that controls the warm-up of the fixing device 9; and a system control unit 101 as a medium detection unit that specifies the residual position of the residual medium P remaining on the main conveyance path R1 and the sub-conveyance path R2 separately from the jammed medium P that caused the jam when a jam occurs on the main conveyance path R1 and the sub-conveyance path R2.

[0071] In the image forming apparatus 100, the automatic discharge control unit 107 performs a discharge operation (main conveyance path automatic discharge operation or sub-conveyance path automatic discharge operation) to discharge the residual medium P after removing the jammed medium P. Further, before the discharge operation, based on the residual position of the residual medium P detected by the system control unit 101, it is determined whether to perform the warm-up of the fixing device 9.

[0072] Specifically, when the residual position of the residual medium P is within the main conveyance path R1 (specifically, between the detection position of the discharge sensor 10, which is an example of the first medium detection unit, and the detection position of the writing sensor 7, which is an example of the third medium detection unit, and is a position before the completion of developer fixing), the automatic discharge control unit 107 determines to perform the warm-up of the fixing device 9, and after performing the warm-up of the fixing device 9, performs the main conveyance path automatic discharge operation to discharge the residual medium P. By doing so, the image forming apparatus 100 can prevent the unfixed developer image from adhering to the fixing device 9, the discharge roller 11, etc. and soiling them.

[0073] On the other hand, when the residual position of the residual medium P is within the sub-conveying path R2 (i.e., when it is the position after the developer fixing is completed), the automatic discharge control unit 107 determines not to perform the warm-up of the fixing device 9, and performs the sub-conveying path automatic discharge operation without performing the warm-up of the fixing device 9, thereby discharging the residual medium P. By doing so, in the image forming apparatus 100, when the residual position of the residual medium P is within the sub-conveying path R2, the time until printing restart at the time of jam occurrence can be shortened by the amount of not performing the warm-up of the fixing device 9.

[0074] [2. Second Embodiment] Next, the second embodiment will be described. This second embodiment is an embodiment in which a jam can be detected even during the automatic discharge operation of the residual medium P. Here, mainly the parts different from the first embodiment will be described, and the description of the same parts will be omitted as appropriate.

[0075] [2-1. Configuration of Image Forming Apparatus] The configuration of the functional units of the image forming apparatus 200 will be described with reference to FIG. 9. Note that the configuration of the mechanical units of the image forming apparatus 200 is the same as that of the first embodiment, and thus the description thereof is omitted. As is clear from a comparison between FIGS. 2 and 9, the functional units of the image forming apparatus 200 have a configuration in which a jam detection unit 118 during automatic discharge execution is added to the automatic discharge control unit 107 of the image forming apparatus 100.

[0076] The jam detection unit 118 during automatic discharge execution detects that a jam has occurred when an abnormality is found in the detection results of each sensor during the automatic discharge operation (for example, when it turns on at a timing when it should not originally turn on).

[0077] [2-2. Operation of Image Forming Apparatus] Next, the operation of the image forming apparatus 200 will be described. Here, as the operation of the image forming apparatus 200, the operation at the time of jam occurrence will be described using the flowcharts shown in FIGS. 10 and 11. Note that the flowcharts shown in FIGS. 10 and 11 are flowcharts in which an operation of detecting a jam during automatic discharge is added to the flowchart shown in FIG. 3, and here, the operation of the added part will be mainly described.

[0078] Note that FIG. 10 shows the operation when the image forming apparatus 200 is in the state shown in FIG. 12, for example, and FIG. 11 shows the operation when the image forming apparatus 200 is in the state shown in FIG. 13, for example. Here, first, the operation when the image forming apparatus 200 is in the state shown in FIG. 12 will be described using the flowchart shown in FIG. 10. In the image forming apparatus 200, for example, when a user performs an operation of opening and closing a cover (not shown) provided on the apparatus housing 20, the state shown in FIGS. 12 and 13 can be obtained.

[0079] Specifically, the state shown in FIG. 12 is a state in which, during double-sided printing, the medium P5 on which printing on the front surface has been completed has reached before the fixing device 9, and the subsequent medium P6 has jammed on the sub-conveying path R2. In this case, after the medium P6 passes through the detection position of the writing sensor 7 and the writing sensor 7 turns off, and the entrance sensor 5 does not turn on even after a predetermined time has elapsed, the system control unit 101 detects the occurrence of a jam in step SP302 shown in FIG. 10. At this time, the system control unit 101 also specifies that a jam has occurred on the sub-conveying path R2. Further, at this time, since the writing sensor 7 turns off when the medium P5 passes through the detection position of the writing sensor 7 and the discharge sensor 10 is not yet on, the system control unit 101 specifies that the medium P5 remains as a remaining medium between the writing sensor 7 and the discharge sensor 10 on the main conveying path R1.

[0080] In the subsequent step SP303, the automatic discharge control unit 107 determines whether to execute the automatic discharge of the residual medium P by the automatic discharge execution presence / absence determination unit 108. Here, since the image forming apparatus 100 at this time is in the state shown in FIG. 12, that is, a jam has occurred during double-sided printing and the residual medium P (medium P5) remains on the main conveyance path R1, the automatic discharge execution presence / absence determination unit 108 determines to execute the automatic discharge of the residual medium P on the main conveyance path R1, and as shown in the table of FIG. 8(A), rewrites the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 to indicate that the automatic discharge is to be executed.

[0081] Thereafter, the process proceeds to steps SP304, SP305, SP306, SP307, and SP308. In step SP308, the automatic discharge control unit 107 starts the main conveyance path automatic discharge operation.

[0082] In the subsequent step SP601, the automatic discharge control unit 107 determines whether the sub-conveyance path automatic discharge execution information stored in the sub-conveyance path automatic discharge execution information storage unit 116 indicates that the automatic discharge is to be executed by the automatic discharge execution presence / absence determination unit 108. At this time, as shown in the table of FIG. 8(A), since the sub-conveyance path automatic discharge execution information indicates that the automatic discharge is not to be executed, the automatic discharge control unit 107 moves to step SP311 without executing the sub-conveyance path automatic discharge operation.

[0083] In step SP311, as shown in the table of FIG. 8(A), since the main conveyance path automatic discharge execution information indicates that the automatic discharge is to be executed, the automatic discharge control unit 107 determines whether the discharge sensor 10 is turned on while operating the predetermined time main motor 14.

[0084] Here, there may be a case where the user forgets to remove the medium P6 shown in FIG. 12 (i.e., the medium that caused the jam). In this case, with the medium P5 remaining on the main conveyance path R1, the main conveyance path automatic discharge operation will be started with the medium P6 remaining on the sub-conveyance path R2. In this main conveyance path automatic discharge operation, since the first conveyance roller 12 and the second conveyance roller 13 on the sub-conveyance path R2 are also driven, not only the medium P5 on the main conveyance path R1 but also the medium P6 on the sub-conveyance path R2 will be conveyed.

[0085] Here, the medium P6 on the sub-conveyance path R2 is likely to be the medium that caused the jam and not a normal medium, and it is not preferable to convey it as it is. For this reason, in the image forming apparatus 200, when the medium P6 on the sub-conveyance path R2 is conveyed during the main conveyance path automatic discharge operation and the entrance sensor 5 is turned on, the jam detection unit 118 during automatic discharge detection detects a jam and causes the user to remove the medium P6.

[0086] Specifically, in the above-described step SP311 shown in FIG. 10, when a negative result is obtained because the discharge sensor 10 is not turned on, the automatic discharge control unit 107 moves to step SP602.

[0087] In step SP602, the automatic discharge control unit 107 determines whether the entrance sensor 5 is turned on by the jam detection unit 118 during automatic discharge. Here, when the entrance sensor 5 is not turned on, the automatic discharge control unit 107 obtains a negative result in step SP602 and returns to step SP311 to determine whether the discharge sensor 10 is turned on. Note that the loop from step SP311 to step SP602 is executed until the discharge sensor 10 or the entrance sensor 5 is turned on within a predetermined time.

[0088] On the other hand, when the entrance sensor 5 is turned on, this means that the medium P6 on the sub-conveyance path R2 has not been removed and the medium P6 has been conveyed to the detection position of the entrance sensor 5. In this case, the jam detection unit 118 during automatic discharge obtains an affirmative result in step SP602 and moves to step SP603.

[0089] In step SP603, during the automatic discharge execution, the jam detection unit 118 detects the occurrence of a jam and proceeds to step SP604. In step SP604, the automatic discharge control unit 107 determines whether to execute the automatic discharge of the residual medium P by the automatic discharge execution determination unit 108.

[0090] At this time, since the discharge sensor 10 is not on and the medium P5 still remains between the writing sensor 7 and the discharge sensor 10, the automatic discharge execution determination unit 108 determines to execute the automatic discharge of the residual medium P on the main conveyance path R1, and as shown in the table of FIG. 8(A), rewrites the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 to indicate that the automatic discharge is to be executed.

[0091] In the subsequent step SP605, the automatic discharge control unit 107 ends the main conveyance path automatic discharge operation that started in step SP308. Along with this, the system control unit 101 ends the initial operation, returns to step SP304, and causes the user to remove the medium P6.

[0092] On the other hand, when the discharge sensor 10 is turned on without the inlet sensor 5 being turned on and a positive result is obtained in step SP311 described above, the automatic discharge control unit 107 proceeds to step SP312, continues the main conveyance path automatic discharge operation, conveys the residual medium P (medium P5) on the main conveyance path R1 toward the stacker 21, and proceeds to the next step SP315.

[0093] In step SP315, the automatic discharge control unit 107 waits until all started automatic discharge operations (here, the main conveyance path automatic discharge operation) are completed. Here, while waiting until all started automatic discharge operations are completed, in step SP606, the automatic discharge control unit 107 determines whether or not the entrance sensor 5 has been turned on by the jam detection unit 118 during automatic discharge execution. Here, when the entrance sensor 5 is turned on, this means that the medium P6 on the sub-conveyance path R2 has not been removed and the medium P6 has been conveyed to reach the detection position of the entrance sensor 5. In this case, the jam detection unit 118 during automatic discharge execution obtains an affirmative result in step SP606 and moves to step SP607.

[0094] In step SP607, the jam detection unit 118 during automatic discharge execution detects the occurrence of a jam and moves to step SP608. In step SP608, the automatic discharge control unit 107 determines whether or not to execute automatic discharge of the residual medium P by the automatic discharge execution determination unit 108.

[0095] At this time, since the discharge sensor 10 is on and the medium P5 is immediately before (or has been) discharged to the stacker 21, the automatic discharge execution determination unit 108 confirms that the medium P5 has been discharged to the stacker 21 (that is, the main conveyance path automatic discharge operation has been completed), and then determines not to execute automatic discharge of the residual medium P on the main conveyance path R1. As shown in the table of FIG. 8(B), the content of the main conveyance path automatic discharge execution information stored in the main conveyance path automatic discharge execution information storage unit 115 is rewritten to indicate that automatic discharge is not executed.

[0096] In the subsequent step SP609, the automatic discharge control unit 107 ends the initial operation, returns to step SP304, and causes the user to remove the medium P6.

[0097] On the other hand, when all the started automatic discharge operations (here, the main conveyance path automatic discharge operation) are completed without the entrance sensor 5 being turned on, the automatic discharge control unit 107 obtains an affirmative result in step SP315 described above and moves to step SP316. Since the operations after step SP316 are the same as those in the first embodiment, the description thereof is omitted. The operation when the image forming apparatus 200 is in the state shown in FIG. 12 is as described above.

[0098] Subsequently, the operation when the image forming apparatus 200 is in the state shown in FIG. 13, for example, will be described using the flowchart shown in FIG. 11.

[0099] Specifically, the state shown in FIG. 13 is a state in which, during double-sided printing, the medium P7 on which printing on the front surface has been completed jams in front of the fuser 9, and the subsequent medium P8 is positioned on the sub-conveyance path R2. In this case, after the medium P7 passes through the detection position of the writing sensor 7 and the writing sensor 7 turns off, and the discharge sensor 10 does not turn on even after a predetermined time has elapsed, the system control unit 101 detects the occurrence of a jam in step SP302 shown in FIG. 11. At this time, the system control unit 101 also specifies that a jam has occurred between the writing sensor 7 and the discharge sensor 10 on the main conveyance path R1. Further, at this time, since the medium P8 passes through the detection position of the discharge sensor 10 and the discharge sensor 10 is off, and the entrance sensor 5 is still not on, the system control unit 101 specifies that the medium P8 remains as a remaining medium on the sub-conveyance path R2.

[0100] In the subsequent step SP303, the automatic discharge control unit 107 determines whether to execute the automatic discharge of the residual medium P by the automatic discharge execution determination unit 108. Here, since the image forming apparatus 100 at this time is in the state shown in FIG. 13, that is, a jam occurs during double-sided printing and the residual medium P (medium P8) remains on the sub-conveying path R2, the automatic discharge execution determination unit 108 determines to execute the automatic discharge of the residual medium P on the sub-conveying path R2, and as shown in the table of FIG. 8(C), rewrites the content of the sub-conveying path automatic discharge execution information stored in the sub-conveying path automatic discharge execution information storage unit 116 to indicate that the automatic discharge is to be executed.

[0101] Thereafter, the process proceeds to steps SP304 and SP305, and in the subsequent step SP610, the automatic discharge control unit 107 determines whether the main-conveying path automatic discharge execution information stored in the main-conveying path automatic discharge execution information storage unit 115 indicates that the automatic discharge is to be executed by the automatic discharge execution determination unit 108. At this time, as shown in the table of FIG. 8(C), since the main-conveying path automatic discharge execution information indicates that the automatic discharge is not to be executed, the automatic discharge control unit 107 moves to step SP309 without executing the main-conveying path automatic discharge operation.

[0102] Thereafter, the process proceeds to steps SP309 and SP310, and in step SP310, the automatic discharge control unit 107 starts the sub-conveying path automatic discharge operation. Here, there is a case where the user may forget to remove the medium (that is, the medium that caused the jam) P7 shown in FIG. 13.

[0103] Therefore, in the image forming apparatus 200, when the medium P7 on the main-conveying path R1 is conveyed and the discharge sensor 10 is turned on during the sub-conveying path automatic discharge operation, the automatic discharge execution jam detection unit 118 detects it as a jam and causes the user to remove the medium P7.

[0104] Specifically, in step SP611 following step SP310, it is determined whether the discharge sensor 10 is on. Here, if the discharge sensor 10 is on, this means that the medium P7 on the main conveyance path R1 has been conveyed and reached the detection position of the discharge sensor 10. In this case, the jam detection unit 118 during automatic discharge obtains an affirmative result in step SP611 and moves to step SP612.

[0105] In step SP612, the jam detection unit 118 during automatic discharge detects the occurrence of a jam and moves to step SP613. In step SP613, the automatic discharge control unit 107 determines whether to execute automatic discharge of the remaining medium P by the automatic discharge execution determination unit 108.

[0106] At this time, since the inlet sensor 5 is not on and the medium P8 still remains on the sub-conveyance path R2, the automatic discharge execution determination unit 108 determines to execute automatic discharge of the remaining medium P on the sub-conveyance path R2, and as shown in the table of FIG. 8(C), rewrites the content of the sub-conveyance path automatic discharge execution information stored in the sub-conveyance path automatic discharge execution information storage unit 116 to indicate that automatic discharge is to be executed.

[0107] In the subsequent step SP614, the automatic discharge control unit 107 ends the sub-conveyance path automatic discharge operation that started in step SP310. Along with this, the system control unit 101 ends the initial operation, returns to step SP304, and causes the user to remove the medium P7.

[0108] On the other hand, if a negative result is obtained in step SP611 described above because the discharge sensor 10 is not on, the automatic discharge control unit 107 moves to step SP313.

[0109] In step SP313, since the sub-conveyance path automatic discharge execution information indicates that automatic discharge is to be executed as shown in the table of FIG. 8(C), the automatic discharge control unit 107 determines whether the inlet sensor 5 is on while operating the main motor 14 for a predetermined time.

[0110] Here, when the entrance sensor 5 is not on, the automatic discharge control unit 107 obtains a negative result in step SP313 and returns to step SP611 to determine whether the discharge sensor 10 is on. Note that the loop from step SP611 to step SP313 is executed until the discharge sensor 10 or the entrance sensor 5 is on within a predetermined time.

[0111] On the other hand, when the entrance sensor 5 is on without the discharge sensor 10 being on, this means that the medium P8 on the sub-conveyor path R2 has been conveyed and reached the detection position of the entrance sensor 5. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP313 and moves to step SP314.

[0112] In step SP314, the automatic discharge control unit 107 continues the sub-conveyor path automatic discharge operation and conveys the residual medium P (medium P8) on the sub-conveyor path R2 toward the stacker 21, and then moves to the next step SP615.

[0113] In step SP615, the automatic discharge control unit 107 determines whether the discharge sensor 10 is on before the write sensor 7 is on. Here, if the discharge sensor 10 is on before the write sensor 7 is on, this means that the medium P7 has not been removed and the medium P7 has reached the detection position of the discharge sensor 10 before the medium P8 reaches the detection position of the write sensor 7. In this case, the automatic discharge control unit 107 obtains an affirmative result in step SP615, moves to step SP612, and by the operations of steps SP612 to SP614, detects a jam, ends the sub-conveyor path automatic discharge operation and the initial operation, returns to step SP304, and causes the user to remove the medium P7.

[0114] On the other hand, when the write sensor 7 is turned on without the discharge sensor 10 being turned on, this means that the medium P7 has been removed and the medium P8 has reached the detection position of the write sensor 7. In this case, the automatic discharge control unit 107 obtains a negative result in step SP615, moves to step SP315, and waits until all the started automatic discharge operations (here, the sub-conveyor path automatic discharge operation) are completed. Then, when the medium P8 is discharged to the stacker 21 and the sub-conveyor path automatic discharge operation is completed, the automatic discharge control unit 107 obtains a positive result in step SP315 as described above and moves to step SP316. The operations after step SP316 are the same as those in the first embodiment, and thus the description thereof is omitted. The operation when the image forming apparatus 200 is in the state shown in FIG. 13 is as described above.

[0115] [2-3. Summary and Effects] As described so far, in the second embodiment, the automatic discharge control unit 107 of the image forming apparatus 200 is provided with an automatic discharge in-progress jam detection unit 118, which is an example of a discharge operation in-progress jam detection unit that detects a jam during an automatic discharge operation.

[0116] Then, in the image forming apparatus 200, for example, during the execution of the main conveyor path automatic discharge operation for automatically discharging the residual medium P on the main conveyor path R1, if the automatic discharge in-progress jam detection unit 118 detects a jam because the medium (jam medium) P that caused the jam remains on the sub-conveyor path R2 without being removed, after aborting the main conveyor path automatic discharge operation (when the residual medium P is located immediately before the stacker 21 or has already been discharged to the stacker 21, after confirming the discharge), the user is notified of the jam and the jam medium P on the sub-conveyor path R2 that caused the jam is removed.

[0117] Also, in the image forming apparatus 200, for example, during the execution of the sub-conveyor automatic discharge operation for automatically discharging the residual medium P on the sub-conveyor path R2, if the jam detection unit 118 detects a jam because the jammed medium P that caused the jam remains on the main conveyor path R1 without being removed, the sub-conveyor automatic discharge operation is aborted, and then the user is notified of the jam and is made to remove the jammed medium P on the main conveyor path R1 that caused the jam.

[0118] By doing so, in the image forming apparatus 200 of the second embodiment, in addition to the effects obtained by the image forming apparatus 100 of the first embodiment, it is possible to prevent a situation in which the image forming apparatus 200 malfunctions due to forcibly discharging the jammed medium P that the user has forgotten to remove by the automatic discharge operation.

[0119] Also, in the image forming apparatus 200, after aborting the discharge of the residual medium P on the sub-conveyor path R2, notifying the user of the jam and having the user remove the jammed medium P on the main conveyor path R1 that caused the jam, the discharge of the residual medium P on the sub-conveyor path R2 is performed again. Also in this case, since the warm-up of the fixing device 9 is omitted, the time until printing resumes when a jam occurs can be shortened.

[0120] [3. Other Embodiments] [3-1. Other Embodiment 1] Note that in the above-described first embodiment, during printing, the image forming apparatus 100 feeds out, for example, a maximum of two media P at intervals on the conveyance path including the main conveyance path R1 and the sub-conveyor path R2 and prints on each of them. However, the present invention is not limited to this, and for example, a maximum of two or more media P may be fed out at intervals on the conveyance path and printed on each of them, or for example, only one medium P may be fed out on the conveyance path, printed on the medium P, and after discharging the medium P, the next medium P may be fed out on the conveyance path.

[0121] When printing by feeding out only one sheet of medium P on the conveyance path, in the image forming apparatus 100, when the system control unit 101 detects a jam, it may notify the user of this and have the user remove the one sheet of medium P on the conveyance path. In addition, on the image forming apparatus 100, it may be possible to switch between a printing mode in which a plurality of sheets of medium P are fed out at intervals on the conveyance path and a printing mode in which only one sheet of medium P is fed out and printed.

[0122] [3-2. Other Embodiment 2] Also, in the first embodiment described above, the image forming apparatus 100 includes a main conveyance path R1 and a sub-conveyance path R2 for double-sided printing. During double-sided printing, the medium P with the developer image fixed on the surface by the fixing device 9 is conveyed by the discharge roller 11 until it passes the first point Pt1, and then the rotation direction of the discharge roller 11 is switched to the reverse direction, so that the medium P is conveyed in the reverse direction and conveyed from the first point Pt1 to the sub-conveyance path R2.

[0123] Not limited to this, for example, a sub-conveyance path having a path different from the sub-conveyance path R2 of the first embodiment described above may be provided to realize double-sided printing on the medium P. The same applies to the second embodiment.

[0124] [3-3. Other Embodiment 3] Furthermore, in the first embodiment described above, during the sub-conveyor automatic discharge operation, without warming up the fuser 9, the residual medium P remaining in the sub-conveyor R2 is conveyed to the stacker 21 at a conveyance speed matching the printing speed during printing and discharged. Not limited to this, in the sub-conveyor automatic discharge operation, since no transfer or fixing of the developer image is performed on the residual medium P, the residual medium P may be conveyed to the stacker 21 and discharged at a conveyance speed even faster than the conveyance speed matching the printing speed during printing before the jam occurred (for example, the maximum conveyance speed that can be set in the image forming apparatus 200). By doing so, the time until printing resumes after a jam occurs can be further shortened. The same applies to the second embodiment. Note that such control of the conveyance speed during sub-conveyor automatic discharge is performed by, for example, the sub-conveyor automatic discharge control unit 111.

[0125] [3-4. Other Embodiment 4] Furthermore, in the first embodiment described above, the image forming apparatus 100 drives each roller and the photosensitive drum 22 by the main motor 14, but not limited to this. For example, a motor for driving the image forming unit 8 and a motor for driving the fuser 9 may be provided separately from the main motor 14, or a motor for driving the discharge roller 11 that needs to switch the conveyance direction may be provided separately from the main motor 14. The same applies to the second embodiment.

[0126] [3-5. Other Embodiment 5] Furthermore, in the first and second embodiments described above, the present invention is applied to the image forming apparatuses 100 and 200 which are electrophotographic printers, but not limited to this. The present invention can be applied not only to printers but also to image forming apparatuses such as multifunction printers as long as they are equipped with an electrophotographic mechanism. Also, the configuration of the mechanism unit of the image forming apparatus 100 shown in FIG. 1 and the configuration of the functional units of the image forming apparatuses 100 and 200 shown in FIGS. 2 and 9 are examples, and the present invention can also be applied to an image forming apparatus having a configuration different from the mechanism unit shown in FIG. 1 and an image forming apparatus having a configuration different from the functional units shown in FIGS. 2 and 9.

[0127] [3-6. Other Embodiment 6] Furthermore, the present invention is not limited to each of the above-described embodiments. That is, the present invention applies to embodiments that arbitrarily combine some or all of the above-described embodiments, and also to embodiments in which some are extracted.

Industrial Applicability

[0128] The present invention can be widely used, for example, in electrophotographic printers.

Explanation of Reference Numerals

[0129] 100, 200... Image forming apparatus, 1... Media supply tray, 2... Media supply roller, 3... Intermediate paper feed roller, 4... First registration roller, 5... Inlet sensor, 6... Second registration roller, 7... Writing sensor, 8... Image forming unit, 9... Fixing unit, 10... Discharge sensor, 11... Discharge roller, 12... First conveying roller, 13... Second conveying roller, 14... Main motor, 20... Apparatus housing, 21... Stacker, 101... System control unit, 102... Connection I / F unit, 103... Image data storage unit, 104... Printing control unit, 105... Media supply control unit, 106... Media conveyance unit, 107... Automatic discharge control unit, 108... Automatic discharge execution presence / absence determination unit, 109... Main conveyance path automatic discharge control unit, 110... W.U control unit, 111... Sub-conveyance path automatic discharge control unit, 112... Fixing control unit, 113... Operation / display unit, 114... Memory unit, 118... Jam detection unit during automatic discharge execution, P... Media, R1... Main conveyance path, R2... Sub-conveyance path.

Claims

1. A conveying unit that conveys a medium along a conveyance path; An image forming unit provided on the conveyance path that forms a developer image on the medium; A fixing unit provided downstream of the image forming unit in the medium conveyance direction on the conveyance path that fixes the developer image on the medium; A control unit that controls the warm-up of the fixing unit; A medium detection unit that specifies the residual position of a residual medium remaining on the conveyance path separately from a jammed medium that caused the jam when a jam occurs on the conveyance path during printing in which the developer image is formed and fixed on the medium; comprising; The control unit: After removing the jammed medium, a discharge operation is performed to discharge the residual medium by the conveying unit, and further, before the discharge operation, based on the residual position of the residual medium specified by the medium detection unit, it is determined whether to perform the warm-up of the fixing unit. An image forming apparatus characterized by the above.

2. The conveyance path: A main conveyance path where the image forming unit and the fixing unit are arranged; It connects a first point downstream of the fixing unit in the medium conveyance direction on the main conveyance path and a second point upstream of the image forming unit in the medium conveyance direction on the main conveyance path, and is composed of a sub-conveyance path for duplex printing for turning over the medium that has passed through the fixing unit and returning it to the upstream side of the image forming unit in the medium conveyance direction. The control unit: When the residual position of the residual medium is within the sub-conveyance path, it is determined not to perform the warm-up of the fixing unit, and by performing the discharge operation without performing the warm-up of the fixing unit, the residual medium remaining in the sub-conveyance path is conveyed from the sub-conveyance path to the main conveyance path and discharged from the main conveyance path to the outside. The image forming apparatus according to claim 1, characterized by the above.

3. A first medium detection unit located between the fixing unit and the first point in the main conveyance path; The image forming apparatus further includes a second medium detection unit located between the second point and the image forming unit in the main conveyance path; The medium detection unit; Based on the detection results of the first medium detection unit and the second medium detection unit, specifying that the residual position of the residual medium is within the sub-conveyance path; The image forming apparatus according to claim 2, characterized in that.

4. The control unit; Without warming up the fixing unit, the residual medium is conveyed and discharged at a conveyance speed higher than that during printing before the jam occurs; The image forming apparatus according to claim 2 or 3, characterized in that.

5. The image forming apparatus further includes a third medium detection unit located between the second medium detection unit and the image forming unit in the main conveyance path; The medium detection unit; Based on the detection results of the first medium detection unit and the third medium detection unit, specifying that the residual position of the residual medium is between the first medium detection unit and the third medium detection unit in the main conveyance path; The control unit; When the residual position of the residual medium is between the first medium detection unit and the third medium detection unit in the main conveyance path, it is determined that the fixing unit is warmed up, and after warming up the fixing unit, the discharge operation is performed to discharge the residual medium from the main conveyance path to the outside; The image forming apparatus according to claim 3, characterized in that.

6. The control unit; After warming up the fixing unit so that the set temperature is the same as that during printing before the jam occurs, the residual medium is conveyed and discharged at the same conveyance speed as that during printing before the jam occurs; The image forming apparatus according to claim 5, characterized in that.

7. No other media detection unit is provided between the first media detection unit and the third media detection unit in the main conveyance path, and the distance between the first media detection unit and the third media detection unit is longer than the length in the conveyance direction of the media. The image forming apparatus according to claim 5, characterized in that.

8. No media detection unit is provided on the upstream side in the media conveyance direction from the second media detection unit in the main conveyance path, and no media detection unit is provided in the sub-conveyance path. The image forming apparatus according to claim 5 or 7, characterized in that.

9. The control unit When the residual position of the residual medium is within the sub-conveyance path, the discharge operation is started without warming up the fixing unit, and then, if the second media detection unit does not detect a medium within a predetermined time, the discharge operation is terminated. The image forming apparatus according to claim 3, characterized in that.

10. The control unit When the residual position of the residual medium is between the first media detection unit and the third media detection unit in the main conveyance path, the fixing unit is warmed up and then the discharge operation is started, and then, if the first media detection unit does not detect a medium within a predetermined time, the discharge operation is terminated. The image forming apparatus according to claim 5, characterized in that.

11. The image forming apparatus further includes a jam detection unit during discharge operation for detecting a jam occurring on the conveyance path during the discharge operation. The control unit When a jam is detected by the jam detection unit during discharge operation during the discharge operation, the discharge operation is aborted. The image forming apparatus according to claim 1, characterized in that.

12. A conveyance unit that conveys a medium along a conveyance path, an image forming unit that is provided on the conveyance path and forms a developer image on the medium, a fixing unit that is provided on the downstream side of the image forming unit in the medium conveyance direction in the conveyance path and fixes the developer image to the medium, a control unit that controls the warm-up of the fixing unit, and a medium detection unit that specifies the remaining position of a remaining medium remaining on the conveyance path separately from a jammed medium that has caused the jam when a jam occurs on the conveyance path during printing in which the developer image is formed and fixed on the medium. A control method for an image forming apparatus, The control unit is configured to perform a discharging operation of discharging the remaining medium by the conveyance unit after removing the jammed medium, and further, before the discharging operation, determine whether to perform warm-up of the fixing unit based on the remaining position of the remaining medium specified by the medium detection unit The control method is characterized by the above.

Images