Image forming apparatus

Abstract

To easily remove a sheet after stopping another discharge mode and improve usability.SOLUTION: A control part, when a discharge part is unavailable and a second conveyance passage is available, executes another discharge mode to discharge a plurality of sheets present in an image forming apparatus to a loading part and stops another discharge mode in the state of leaving the sheets to a detection position of a sheet detecting part. The control part, after stopping another discharge mode, forces a sheet conveyance part to discharge the sheets present in the detection position of the sheet detecting part to the loading part (S34) in response that an open / closed detecting part detects a change in the open / closed state of an open / closed part (Y of S31, Y of S32).SELECTED DRAWING: Figure 7

Description

Technical Field

[0004] , , , , , , ,

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet.

Background Art

[0002] For example, in image forming apparatuses such as printers, copiers, and multifunction peripherals, when a paper jam (so-called jam) occurs in a sheet, it is common to display the location of the jam to the user and notify the user to remove the jammed sheet. Further, when a paper jam occurs in a sheet, if a sheet other than the jammed sheet is being conveyed through the conveyance path of the image forming apparatus and the conveyance of that sheet is stopped, that sheet will be left inside the image forming apparatus and the user will need to remove it. Particularly when the conveyance path of the image forming apparatus is long, when a paper jam occurs, the number of sheets being conveyed increases, many sheets are left behind, and the user's workload increases. Therefore, when a paper jam occurs, a proposed method is to convey the paper to a branch conveyance path that branches from the conveyance path through which the paper was being conveyed, and discharge the paper from the branch conveyance path to a jam paper storage box (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a configuration where, as described in Patent Document 1 above, when a paper jam occurs, the sheet that was scheduled to be discharged from the discharge section is discharged to another section (hereinafter referred to as the "loading section") and loaded, providing a sensor to detect the sheet in the loading section would hinder cost reduction. Therefore, it has been considered to use a sensor located in the sheet transport path near the loading section, and by stopping the sheet at the sensor's detection position, the system detects that there is a sheet in the loading section and notifies the user to remove the sheet from the loading section. However, the sheet stopped at the sensor's detection position, especially if the sheet is small, may be difficult to see even if the user opens the door to remove the sheet from the loading section, making it difficult for the user to notice. Therefore, there is a risk that the user may not notice the sheet at the sensor's detection position and may not be able to dismiss the notification prompting the removal of the sheet, which is not good in terms of usability.

[0005] Therefore, the present invention aims to provide an image forming apparatus that facilitates the removal of the sheet after the termination of a separate discharge mode, thereby improving usability. [Means for solving the problem]

[0006] One aspect of the present invention includes an image forming unit for forming an image on a sheet, a discharge unit for discharging the sheet on which the image has been formed by the image forming unit to the outside, a first transport path for transporting the sheet on which the image has been formed by the image forming unit to the discharge unit, a second transport path branching off from the first transport path at a first branching section, a sheet transport unit for transporting the sheet in the second transport path, a loading section for loading the sheet discharged from the second transport path, an opening / closing unit that opens and closes to a closed state covering the loading section and an open state opening the loading section, a sheet detection unit for detecting a sheet at a detection position in the second transport path, and the opening / closing The image forming apparatus comprises: an opening / closing detection unit for detecting the opening / closing state of a section; and a control unit that, when the discharge section is unusable and the second transport path is usable, executes an alternative discharge mode for discharging a plurality of sheets inside the apparatus to the loading section, and terminates the alternative discharge mode with a sheet remaining at the detection position; wherein, after the termination of the alternative discharge mode, the control unit executes a sheet movement mode for discharging a sheet at the detection position to the loading section in response to the sheet transport unit detecting a change in the opening / closing state of the opening / closing section by the opening / closing detection unit.

[0007] One aspect of the present invention includes an image forming unit for forming an image on a sheet, a discharge unit for discharging the sheet on which the image has been formed by the image forming unit to the outside, a first transport path for transporting the sheet on which the image has been formed by the image forming unit to the discharge unit, a second transport path branching off from the first transport path at a first branching section, a reversal unit positioned in the second transport path for transporting the sheet on which the image has been formed by the image forming unit in a first direction and then reversing it by transporting it in a second direction opposite to the first direction, a loading unit for loading the sheet that has been transported from the second transport path in the first direction and discharged, an opening / closing unit that opens and closes to cover the loading unit and to open the loading unit, and a detection unit for detecting the sheet at a first position in the second transport path. The image forming apparatus comprises: a first sheet detection unit; a second sheet detection unit that detects a sheet located at a second position in the second direction relative to the first position; an opening / closing detection unit that detects the opening / closing state of the opening / closing unit; and a control unit that, when the discharge unit is unusable and the second transport path is usable, executes an alternative discharge mode in which a plurality of sheets located inside the apparatus are discharged to the loading unit, and terminates the alternative discharge mode with a sheet remaining at the first position, wherein, after the termination of the alternative discharge mode, the control unit executes a sheet movement mode in which the sheet located at the first position is transported to the second position in response to the detection of a change in the opening / closing state of the opening / closing unit by the opening / closing detection unit using the reversal unit. [Effects of the Invention]

[0008] According to the present invention, the sheet can be easily removed after stopping the other discharge mode, thereby improving usability. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram showing an image forming apparatus according to the first embodiment. [Figure 2] A block diagram showing the control configuration of an image forming apparatus according to the first embodiment. [Figure 3] A time chart showing the reversal operation in the reversal unit according to the first embodiment. [Figure 4]A flowchart illustrating the control of the printing operation according to the first embodiment. [Figure 5] A flowchart illustrating the control of the operation for determining the number of sheets to be evacuated in the discharge process according to the first embodiment. [Figure 6] A flowchart illustrating the control of the retraction and discharge operation in the discharge process according to the first embodiment. [Figure 7] A flowchart illustrating the paper movement process according to the first embodiment. [Figure 8] (a) A diagram showing the position of the retained paper when a paper jam occurs during the discharge process. (b) A diagram showing the state when the discharge of retained paper has started during the discharge process. (c) A diagram showing the state when the retained paper has been discharged to the retraction section during the discharge process. (d) A diagram showing the state when the last retained paper has stopped at the detection position of the inversion / double-sided transport guide sensor during the discharge process. [Figure 9] A schematic diagram showing the position of paper when a paper jam occurs. [Figure 10] A diagram showing an example of a notification screen. [Figure 11] A flowchart illustrating the paper movement process according to the second embodiment. [Figure 12] A flowchart illustrating the paper movement process according to the third embodiment. [Figure 13] (a) is a diagram showing the position of the final sheet at the end of the discharge process according to the third embodiment. (b) is a diagram showing the movement of the final sheet by the final sheet movement control according to the third embodiment. (c) is a diagram showing the completion of the movement of the final sheet by the final sheet movement control according to the third embodiment. [Modes for carrying out the invention]

[0010] <First Embodiment> Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The first embodiment described below is illustrative, and the present invention is not limited to this embodiment.

[0011] [Image forming apparatus] First, the structure of the image forming apparatus according to the first embodiment will be described. FIG. 1 is a schematic diagram showing the image forming apparatus according to the first embodiment. In FIG. 1, the image forming apparatus 100 is a color laser printer, and roughly includes an image output unit 100P as a device main body, a reader unit 104 disposed above the image output unit 100P, and an operation unit 105. The image output unit 100P forms an image so as to copy the image of the document read by the reader unit 104 when operated via the operation unit 105. Alternatively, the image output unit 100P forms an image based on image data recorded in a hard disk drive or the like (not shown) or image data input from an external interface (not shown).

[0012] The image output unit 100P includes an image forming unit 10, a feeding unit 20, an intermediate transfer unit 30, a fixing unit 40, a reversing unit 50, a duplex conveying unit 60, a discharging conveying unit 70, a control unit 80, and a retracting unit 90. In the present image forming apparatus 100, an image forming unit 100A for forming an image on a sheet of paper P is constituted by the image forming unit 10, the intermediate transfer unit 30, and the fixing unit 40. Further, in the present image forming apparatus 100, a door 120 as an opening / closing unit that covers the reversing unit 50 and the retracting unit 90 in the closed state and opens the reversing unit 50 and the retracting unit 90 in the open state to enable removal of the paper is provided as an exterior of the image output unit 100P.

[0013] The image forming unit 10 includes four image forming stations a to d arranged side by side along the horizontal direction. The configurations of the four image forming stations a to d are the same. That is, each of the image forming stations a to d includes a photosensitive drum 11a to 11d as an image carrier that is pivotally supported at its center and rotationally driven. The photosensitive drums 11a to 11d rotate in the direction of the arrows in FIG. 1, respectively. Along the rotation direction so as to face the outer peripheral surfaces of the photosensitive drums 11a to 11d, primary charging devices 12a to 12d, optical systems 13a to 13d, developing devices 14a to 14d, and cleaning devices 15a to 15d are arranged, respectively.

[0014] The primary charging devices 12a to 12d apply charges with a uniform charge amount to the surfaces of the corresponding photosensitive drums 11a to 11d. The optical systems 13a to 13d expose light beams such as laser beams, which are modulated according to the recording image signals, onto the corresponding photosensitive drums 11a to 11d to form electrostatic latent images on each of the photosensitive drums 11a to 11d. The developing devices 14a to 14d store yellow, cyan, magenta, and black toners respectively, and supply toner to the electrostatic latent images formed on the corresponding photosensitive drums 11a to 11d to form toner images and visualize them. The toner images formed on the photosensitive drums 11a to 11d are transferred onto the intermediate transfer belt 31 so as to overlap by applying a predetermined transfer voltage to the primary transfer rollers 35a to 35d of the intermediate transfer unit 30 described later, thereby forming a color image. The cleaning devices 15a to 15d scrape off the residual toner remaining on the photosensitive drums 11a to 11d that is not transferred onto the intermediate transfer belt 31 to clean the surfaces of the photosensitive drums 11a to 11d.

[0015] The paper feed unit 20 includes a cassette 21 that stores paper P as a sheet or recording paper, and a pickup roller 22 that feeds out the paper P from the cassette 21. The paper feed unit 20 includes a manual feed tray 97 and a manual pickup roller 96 that feeds out the paper P from the manual feed tray 97. Further, the paper feed unit 20 includes a registration roller pair 26, a pre-registration roller pair 27 that can be separated, a plurality of conveyance roller pairs 23 that convey the paper P sent out from the cassette 21 to the registration roller pair 26, and a conveyance path 24. An edge sensor 28 that detects the presence or absence of the paper P is disposed upstream of the registration roller pair 26 in the conveyance path 24. Also, a secondary transfer pre-sensor 29 is disposed downstream of the registration roller pair 26 in the conveyance path 24.

[0016] Note that the cassette 21 is provided with a sensor as a size detector that detects the size of the paper P accommodated in the cassette 21. Also, the edge sensor 28 and the secondary transfer pre-sensor 29 are examples of conveyance sensors, and have a plurality of conveyance sensors 106 that monitor the paper position as shown in FIG. 2.

[0017] Furthermore, in this embodiment, the transport path refers to the space demarcated by transport guides, which are guide sections that physically contact the paper P (sheet) and guide the paper P in the transport direction. Since this transport path on which the sheet is transported is composed of guide members, it may be rephrased as a guide section that guides the sheet being transported.

[0018] The pickup roller 22 feeds the paper P from the cassette 21, and the fed paper P is transported to the registration roller pair 26 by the transport roller pair 23. On the other hand, when paper P is fed from the manual feed tray 97, the manual feed pickup roller 96 feeds the paper P from the manual feed tray 97, and the fed paper P is transported to the registration roller pair 26 by the pre-registration roller pair 27. The registration roller pair 26 feeds the paper P toward the secondary transfer area Te of the intermediate transfer unit 30, which will be described later, in accordance with the timing of image formation.

[0019] The intermediate transfer unit 30 includes an intermediate transfer belt 31. The intermediate transfer belt 31 is rotatably stretched by a drive roller 32, a tension roller 33, and a secondary transfer inner roller 34. The drive roller 32 transmits driving force to the intermediate transfer belt 31. The tension roller 33 provides appropriate tension to the intermediate transfer belt 31. A secondary transfer outer roller 36 is positioned opposite the secondary transfer inner roller 34, with the intermediate transfer belt 31 in between. The contact area between the secondary transfer inner roller 34 and the secondary transfer outer roller 36 becomes the secondary transfer region Te. Primary transfer rollers 35a to 35d are positioned opposite each of the photosensitive drums 11a to 11d via the intermediate transfer belt 31. The contact areas between the photosensitive drums 11a to 11d and the primary transfer rollers 35a to 35d become the primary transfer regions Ta to Td, respectively. A cleaning device 37 is positioned opposite the tension roller 33 via the intermediate transfer belt 31. The cleaning device 37 cleans the image forming surface of the intermediate transfer belt 31.

[0020] The fixing unit 40 includes a fixing roller 41a and a pressure roller 41b that presses against the fixing roller 41a. The fixing roller 41a has a heat source such as a halogen heater inside. In some cases, the pressure roller 41b also has a heat source. The transport path 43 of the fixing unit 40 is provided with a pair of pre-fixing rollers 42 that transport the paper P to the nip between the fixing roller 41a and the pressure roller 41b.

[0021] The discharge and transport unit 70 includes an internal discharge roller pair 71, an external discharge roller pair 72 as a discharge section, a flapper 73 as a first branching section, and transport paths 74, 75, and 76 as first transport paths. The internal discharge roller pair 71 transports the paper P on which the image has been heat-fixed by the fixing unit 40. The external discharge roller pair 72, as a discharge section, discharges the paper P toward the outside of the main body of the device. The flapper 73 as a first branching section is a branching mechanism that switches the destination of the paper P to transport path 74 or transport path 75 using a reversing / double-sided flapper solenoid 95. In other words, it switches the destination of the paper P to either the direction of the reversing unit 50 (described later) or the direction of the external discharge roller pair 72.

[0022] In this embodiment, the transport path 74 constitutes a first transport path that transports the paper P transported from the image forming unit 100A to the external discharge roller pair 72, which serves as the discharge unit. The transport path 75, which branches off from the transport path 74, constitutes a second transport path that transports the paper P transported from the image forming unit 100A to the retraction unit 90, which serves as the loading unit, as described later. The transport path 76, which branches off from the transport path 75, constitutes a fourth transport path that transports the paper P, which has been inverted by the inversion unit 50, which serves as the inversion unit, to the external discharge roller pair 72, which serves as the discharge unit.

[0023] The reversing unit 50, which functions as a sheet transport unit or reversing unit, includes a first reversing / double-sided roller pair 51A (first roller) and a second reversing / double-sided roller pair 51B (second roller) as a first transport unit. The reversing unit 50 also includes a transport path 52 as a second transport path and a discharge flapper 53 as a third branching unit. Furthermore, the reversing unit 50 includes a second reversing / double-sided flapper 54 as a second branching unit and a reversing / retraction roller pair 55 as a second transport unit. The reversing unit 50 also includes a second reversing / double-sided sensor 91 as a second sheet detection unit and a reversing / double-sided transport guide sensor 92 as a sheet detection unit or first sheet detection unit. Finally, the reversing unit 50 includes a first reversing / double-sided drive motor 93 as a first drive source and a second reversing / retraction drive motor 99 as a second drive source.

[0024] The first reversing / double-sided roller pair 51A and the second reversing / double-sided roller pair 51B are driven by the reversing / double-sided drive motor 93 and are configured to rotate in both forward and reverse directions. The reversing / retracting roller pair 55 is driven by the reversing / retracting drive motor 99 and is similarly configured to rotate in both forward and reverse directions. In other words, the first reversing / double-sided roller pair 51A, the second reversing / double-sided roller pair 51B, and the reversing / retracting roller pair 55 are capable of transporting the paper P conveyed from the image forming unit 100A toward the retraction unit 90 in either the first direction A or the opposite second direction B.

[0025] The discharge flapper 53 is a branching mechanism that, when reversed and discharged, switches the destination of the paper P, which has been reversed in the transport path 52, to the transport path 76 that branches off from the transport path 52, using the reverse / duplex flapper solenoid 95. In other words, it switches the destination of the paper P towards the outer discharge roller pair 72 of the discharge transport unit 70. The reverse / duplex flapper 54 is a branching mechanism driven by the reverse / duplex flapper solenoid 95 that, when a duplex printing job is executed, switches the destination of the paper P towards the transport path 62 that branches off from the transport path 52, which will be described later. The reverse / duplex flapper 54 switches the destination of the paper P towards each duplex transport roller pair 61 of the duplex transport unit 60.

[0026] The reversal / duplex sensor 91 detects the presence or absence of a sheet of paper P at a second detection position 91A between the reversal / duplex flapper 54 and the first reversal / duplex roller pair 51A in the paper P transport direction, and detects the leading and trailing ends of the paper P during reversal ejection and duplex printing. In other words, the reversal / duplex sensor 91 detects a sheet that is in a position to be transported by the reversal pull-in roller pair 55.

[0027] Furthermore, the inversion / double-sided transport guide sensor 92 detects the presence or absence of paper P at the first detection position 92A between the second inversion / double-sided roller pair 51B and the retraction section 90. In other words, the inversion / double-sided sensor 91 is located upstream of the inversion / double-sided transport guide sensor 92 in the first direction A, which is the transport direction of paper P, and is positioned on the side of the image forming section 100A. The inversion / double-sided transport guide sensor 92 also detects sheets that are in a position where they can be transported by either the first inversion / double-sided roller pair 51A or the second inversion / double-sided roller pair 51B.

[0028] The double-sided transport unit 60 includes a pair of double-sided transport rollers 61 for transporting the paper P, and a transport path 62 as a third transport path for transporting the paper P, which has been inverted by the inversion unit 50, to the image forming unit 100A.

[0029] The control unit 80 incorporates a CPU 111 as a control unit. The CPU 111 controls the various mechanisms within each of the aforementioned units to perform various operations.

[0030] The retraction section 90 is configured to retract the leading edge (rear edge after reversal) of the paper P that is reversed by the reversal unit 50, and is configured to retract paper that has accumulated in the transport path when a paper jam occurs, as will be described later. Specifically, the retraction section 90 is connected to the transport path 52 of the reversal unit 50 and is provided in close proximity to the reversal unit 50. The retraction section 90 includes a paper stopper section 90Y and a paper stopper section 90X. The leading edge of the paper P in the transport direction that is discharged into the retraction section 90 comes into contact with the paper stopper section 90Y. The paper stopper section 90X comes into contact with the other end of the paper P that has bounced back after coming into contact with the paper stopper section 90Y, and stops the paper P.

[0031] The door 120, which serves as the opening and closing mechanism, changes between a closed state and an open state as described above; in other words, it is a door that can be opened and closed, and is configured so that the closed or open state is detected by the door sensor 121, which serves as the opening and closing detection mechanism.

[0032] Next, the control configuration of the image forming apparatus 100 will be described. Figure 2 is a block diagram showing the control configuration of the image forming apparatus shown in Figure 1. In Figure 2, the image forming apparatus 100 is equipped with a CPU 111 as a control unit. The CPU 111 is connected to the operation unit 105, image memory 107, ROM 108, and RAM 112, respectively. It is also connected to the reversing / double-sided drive motor 93, reversing / double-sided flapper solenoid 95, reversing / double-sided sensor 91, and reversing / double-sided transport guide sensor 92. Furthermore, it is connected to the pickup motor 94, manual pickup motor 98, reversing / pull-in drive motor 99, transport sensor 106, and door sensor 121. The CPU 111 centrally controls each part of the image forming apparatus 100 and executes various processes by loading various programs stored in the ROM 108 into the RAM 112.

[0033] The operation unit 105 is equipped with a key operation unit having various keys, and accepts various operation inputs from the user to the key operation unit (single-sided / double-sided printing mode, reverse ejection mode, paper size, paper basis weight, number of prints, etc.), and outputs the input operation signals to the CPU 111. The operation unit 105 is equipped with a display unit for informing the user of various information. The operation unit 105 is also equipped with a setting unit for the user to set the size of the paper P. The image memory 107 is a storage unit that temporarily stores information such as image data received from an external device. The ROM 108 is a storage unit dedicated to reading information.

[0034] The pickup motor 94 receives a drive signal from the CPU 111 and drives the pickup roller 22 to feed paper P from the cassette 21. The manual feed pickup motor 98 also receives a drive signal from the CPU 111 and drives the manual feed pickup roller 96 to feed paper P from the manual feed tray 97.

[0035] The inversion / duplex sensor 91 is composed of an optical sensor equipped with, for example, a light-emitting element and a light-receiving element. It detects the presence or absence of the paper P being transported by the inversion unit 50 at the second detection position 91A in the transport path 52, as well as the trailing and leading edges of the paper, and outputs the detection result to the CPU 111. Specifically, this optical sensor has a light-emitting element that illuminates the paper in the retraction section with light and a light-receiving element that receives the reflected light reflected by the paper. This optical sensor detects whether or not paper is present at the second detection position 91A, which is the detection position of the inversion / duplex sensor 91 in the transport path 52, and outputs the result to the CPU 111. Upon receiving the detection result, the CPU 111 expands the detection result into RAM 112 and stores it. Similarly, the inversion / duplex transport guide sensor 92 is also composed of an optical sensor equipped with, for example, a light-emitting element and a light-receiving element. This optical sensor also detects the presence or absence of the paper P being transported by the inversion unit 50 at the first detection position 92A in the transport path 52, as well as the trailing and leading edges of the paper, and outputs the detection result to the CPU 111.

[0036] The reversing pull-in drive motor 99 receives necessary information for driving, such as CW / CCW rotation signals and drive start signals, from the CPU 111 and drives the reversing pull-in roller pair 55. Similarly, the reversing / double-sided drive motor 93 receives necessary information for driving, such as CW / CCW rotation signals and drive start signals, from the CPU 111 and drives the reversing / double-sided roller pair 51. The reversing / double-sided flapper solenoid 95 operates the reversing / double-sided flapper 54 to switch the destination of the paper P.

[0037] [Image Formation Process] Next, the operation of the image forming apparatus 100 according to this embodiment will be described. When an operation start signal is issued to start the image forming operation, first, the pickup roller 22 feeds out one sheet of paper P at a time from the cassette 21. Next, the transport roller pair 23 guides the paper P along the transport path 24, transporting it through the pre-register roller pair 27 to the registration roller pair 26. At this time, the registration roller pair 26 is stopped. When the paper P comes into contact with the stopped registration roller pair 26, it forms a loop (bend), thereby correcting the skew of the paper P. After that, the registration roller pair 26 starts rotating in conjunction with the timing when the image is formed in the image forming unit 10. The timing of when the registration roller pair 26 starts rotating is set so that the paper P and the toner image transferred from the image forming unit 10 onto the intermediate transfer belt 31 coincide in the secondary transfer area Te.

[0038] On the other hand, in the image forming unit 10, when an operation start signal is issued to start the image forming operation, the toner image formed on the photosensitive drum 11d, which is located on the upstream side in the rotational direction of the intermediate transfer belt 31, is transferred to the intermediate transfer belt 31 through the process described above. That is, a high voltage for transfer is applied to the primary transfer roller 35d, which is positioned opposite the photosensitive drum 11d, and in the primary transfer region Td, the toner image formed on the photosensitive drum 11d is transferred to the intermediate transfer belt 31.

[0039] The toner image transferred onto the intermediate transfer belt 31 is transported to the next primary transfer area Tc. On the photosensitive drum 11c, an image is formed with a delay compared to the photosensitive drum 11d, equal to the time it takes for the toner image to be transported between the image forming units. The resist is then aligned with the toner image transferred to the intermediate transfer belt 31, and the toner image on the photosensitive drum 11c is transferred. The same process is repeated thereafter, and the four toner images formed on the photosensitive drums 11d to 11a are transferred onto the intermediate transfer belt 31 so that they overlap.

[0040] Subsequently, when the paper P enters the secondary transfer area Te and comes into contact with the intermediate transfer belt 31, a high voltage is applied to the secondary transfer outer roller 36 in accordance with the timing of the paper P's passage. When a high voltage is applied to the secondary transfer outer roller 36, the toner image formed on the intermediate transfer belt 31 is transferred to the surface of the paper P. The paper P with the transferred toner image is then transported by the transport path 43 to the nip section between the fixing roller 41a and the pressure roller 41b of the fixing unit 40. There, the heat and nip pressure from the fixing roller 41a and the pressure roller 41b fix the toner image to the surface of the paper P.

[0041] The paper P on which the toner image has been fixed is fed out by the internal discharge roller pair 71. During single-sided printing and after printing on the back side during double-sided printing, the flapper 73 operates to guide the paper P toward the transport path 74 where the external discharge roller pair 72 is located, and the external discharge roller pair 72 discharges the paper P from the image output unit 100P to the outside. On the other hand, when executing a reverse discharge job or when forming an image on the back side of the paper P after printing on the front side of a double-sided printing job, the flapper 73 operates to guide the paper P toward the transport path 75 where the reversal unit 50 is located.

[0042] The paper P, which has been drawn into the reversal unit 50, is drawn into the transport path 52 by the reversal pull-in roller pair 55, the first reversal / double-sided roller pair 51A, and the second reversal / double-sided roller pair 51B. When the rear end of the paper P is detected by the reversal / double-sided sensor 91, the transport of the paper P is temporarily stopped. Subsequently, in the case of reverse discharge, the reversal pull-in roller pair 55, the first reversal / double-sided roller pair 51A, and the second reversal / double-sided roller pair 51B rotate in the opposite direction, and the paper P is transported in the direction of the outer discharge roller pair 72 by the transport path 76 through the operation of the discharge flapper 53. The paper P transported to the outer discharge roller pair 72 is discharged to the outside of the image output unit 100P.

[0043] On the other hand, in the case of a double-sided printing job, the paper P is transported in the direction of the transport path 62 where the double-sided transport unit 60 is located by the operation of the inversion / double-sided flapper 54. The paper P guided to the transport path 62 of the double-sided transport unit 60 is transported by the double-sided transport roller pair 61 and joins the transport path 24 of the feeding unit 20 for front-side printing. After that, an image is formed on the back side of the paper P through a process similar to that for front-side printing. The paper P, with images formed on both sides in this way, is then discharged to the outside of the image output unit 100P by the external discharge roller pair 72.

[0044] [Operation of the inversion unit 50] Figure 3 is a timing chart of the inversion / duplex sensor 91, inversion / duplex drive motor 93, inversion pull-in drive motor 99, and inversion / duplex flapper solenoid 95 in an inversion / duplex printing job. In Figure 3, first, when the paper P is loaded into the inversion unit 50, the inversion / duplex flapper solenoid 95 (i.e., the inversion / duplex flapper 54) is in the home position (HP). That is, the inversion / duplex flapper solenoid 95 is in the OFF state, and the inversion / duplex flapper 54 is switched to a position that forms a downward (first direction A) flow path in Figure 1 for transporting the paper P to the transport path 52.

[0045] In this state, the CPU 111 outputs a drive ON signal and a rotation direction CW signal to the reversing / double-sided drive motor 93 and the reversing / retraction drive motor 99. These signals cause the reversing / retraction roller pair 55, the first reversing / double-sided roller pair 51A, and the second reversing / double-sided roller pair 51B to rotate, and downward transport of the paper P towards the first direction A begins.

[0046] One hour after the reversal / duplex drive motor 93 and the reversal retraction drive motor 99 start driving, the reversal / duplex sensor 91 detects the leading edge of the paper P and turns ON. Then, two hours later, the reversal / duplex sensor 91 detects the trailing edge of the paper P and turns OFF. Three hours after the reversal / duplex sensor 91 detects the trailing edge of the paper P, the reversal / duplex drive motor 93 and the reversal retraction drive motor 99 are stopped. As a result, the rotation of the reversal retraction roller pair 55, the first reversal / duplex roller pair 51A, and the second reversal / duplex roller pair 51B stops.

[0047] During the t4 time period when the reversing / double-sided drive motor 93 is stopped, the reversing / double-sided flapper solenoid 95 turns ON, and the reversing / double-sided flapper 54 switches to a direction that guides the paper P to the transport path 62 of the double-sided transport unit 60. When the reversing / double-sided flapper solenoid 95 is ON, the CPU 111 outputs a drive ON signal and a rotation direction CCW signal to the reversing / double-sided drive motor 93. As a result of these signals, the paper P is transported in the second direction B by the first reversing / double-sided roller pair 51A and the second reversing / double-sided roller pair 51B, and transported towards the double-sided transport unit 60.

[0048] t5 hours after the reversing / double-sided drive motor 93 starts rotating, the reversing / double-sided sensor 91 detects the leading edge of the paper P. t6 hours after detecting the leading edge, the reversing / double-sided sensor 91 detects the trailing edge of the paper P and turns OFF. t7 hours after the reversing / double-sided sensor 91 turns OFF, the reversing / double-sided drive motor 93 stops, and the rotation of the reversing / double-sided roller pair 51 stops. t8 hours after the reversing / double-sided drive motor 93 stops, the reversing / double-sided flapper solenoid 95 turns OFF, and the reversing / double-sided flapper 54 returns to its initial state, forming a flow path for transporting the paper P in the first direction A.

[0049] [Paper jam disposal procedure] Next, we will explain what happens when a paper jam occurs in the external discharge roller pair 72 and the transport path 74, or when a paper jam occurs in a processing device such as a finisher, binding device, or cutting device connected to the transport path 74. In other words, we will explain the discharge process when the external discharge roller pair 72 and the transport path 74 become unusable, but the transport path 75 and the transport path 52 are usable, using Figures 4 to 10.

[0050] (Overview of waste disposal operation) First, when a paper jam occurs as described above, the general operation of moving the retained paper P (hereinafter referred to as "retained paper Pt") inside the image forming apparatus 100 to the retraction section 90 will be explained using Figure 8. Figure 8(a) shows the position of the retained paper when a paper jam occurs during the discharge process, and Figure 8(b) shows the state in which the discharge of retained paper has started during the discharge process. Furthermore, Figure 8(c) shows the state in which the retained paper has been discharged to the retraction section during the discharge process, and Figure 8(d) shows the state in which the last retained paper has stopped at the detection position of the inversion / double-sided transport guide sensor during the discharge process.

[0051] First, we will briefly explain the operation when paper jams occur in the transport paths 75 and 52 from the fixing unit 40 to the reversal / double-sided sensor 91 of the reversal unit 50. As shown in Figure 8(a), suppose that paper jams occur in the transport paths 75 and 52 when the external discharge roller pair 72 and transport path 74 become unusable. In this case, the paper jammed in the transport paths 75 and 52 is transported in the first direction A (downward in the figure) by the internal discharge roller pair 71, the reversal / pull-in roller pair 55, the first reversal / double-sided roller pair 51A, and the second reversal / double-sided roller pair 51B, as shown in Figure 8(b). Then, as shown in Figure 8(c), all of the paper jammed paper that has been sent to the second reversal / double-sided roller pair 51B is discharged into the retraction section 90 and loaded. This prevents paper jams from scattering in various places, simplifying the user's recovery work.

[0052] Incidentally, the retraction unit 90 is not equipped with sensors to detect the presence or absence of paper P, for the purpose of cost reduction, etc. Therefore, as shown in Figure 8(c), if all the stagnant paper Pt is discharged to the retraction unit 90, it is not possible to detect whether or not there is stagnant paper Pt in the retraction unit 90, and there is a risk that the sensor will not be able to detect the stagnant paper Pt, for example, if the RAM 112 is erased when the power is turned off. Therefore, as shown in Figure 8(d), the last of the multiple stagnant paper Pt is stopped at a position (detection position) where it can be detected by the first detection position 92A of the inversion / double-sided transport guide sensor 92 of the transport path 52. This makes it possible to detect the stagnant paper Pt in the retraction unit 90 even if the stagnant paper Pt cannot be detected in the retraction unit 90, and to notify the user that there is stagnant paper Pt in the retraction unit 90 and the inversion unit 50. However, if another paper jam occurs and the stagnant paper Pt cannot be stopped at the detection position of the inversion / double-sided transport guide sensor 92, the stagnant paper Pt cannot be detected, and such notification may not be possible. Therefore, in this embodiment, the discharge process is carried out as follows.

[0053] (Details of paper jam removal procedures) Next, in this embodiment, the discharge process when a paper jam occurs during printing and the accumulated paper Pt is discharged to the retraction unit 90 will be explained using Figures 4, 5, 6, 9, and 10. Figure 4 is a flowchart showing the control of the printing operation according to this embodiment. Figure 5 is a flowchart showing the control of the retraction count determination operation in the discharge process according to this embodiment, and Figure 6 is a flowchart showing the control of the retraction discharge operation in the discharge process according to this embodiment. Figure 9 is a schematic diagram showing the position of the paper when a paper jam occurs. And Figure 10 is a diagram showing an example of a notification screen.

[0054] <Printing operation> As shown in Figure 4, when a print job is input by, for example, operation of the control unit 105, the CPU 111 starts controlling the printing operation. First, it monitors whether or not a paper jam has occurred (S1), and as long as no paper jam has occurred (N in S1), this monitoring is repeated until the output of the last sheet to the outside is complete (N in S2). After that, if no paper jam occurs (N in S1) and the output of the last sheet in the print job to the outside is complete (Y in S2), the printing operation is terminated.

[0055] On the other hand, if a paper jam is detected during printing (Y in S1), the process proceeds to step S3, where the process of ejecting the stagnant paper Pt to the retraction section 90 in the event of a paper jam is executed. This ejection process can be described as a separate ejection mode in which the paper inside the device is ejected to the retraction section 90, in addition to the normal ejection mode in which no paper jam occurs and the paper is ejected from the external ejection roller pair 72. Details of this ejection process in step S3 will be described later. After that, the process proceeds to step S4, where a screen indicating a paper jam is displayed on the operation unit 105, for example, a screen prompting the user to remove the stagnant paper Pt accumulated in the retraction section 90, as shown in Figure 10, and the printing operation is interrupted or terminated.

[0056] <Disposal> When the ejection process in step S3 is started (when the ejection process in step S3 is in progress), the CPU 111 proceeds to step S11, as shown in Figure 5. In step S11, the CPU 111 sorts the accumulated paper inside the image forming apparatus 100 into paper to be moved to the retraction unit 90 and paper to be stopped in place without being moved. That is, when a paper jam occurs, the CPU 111 performs a process to determine whether or not to move each piece of accumulated paper to the retraction unit 90. The order in which the CPU determines whether or not to move each piece of accumulated paper to the retraction unit 90 is the order in which the papers are scheduled to be ejected, and in the example shown in Figure 9, the order is accumulated papers 751, 752, 753, 754, and 755.

[0057] In detail, the CPU 111 manages the position of stagnant paper inside the image forming apparatus 100 based on the time elapsed since detection by each transport sensor. When the CPU 111 detects a paper jam of stagnant paper 751 using the transport sensor 106 located near the external discharge roller pair 72 which serves as the discharge section, it determines that the stagnant paper 751 is not to be transported to the retraction section 90 because it has passed the branching point (flapper 73) of the transport path 75 to the retraction section 90. On the other hand, it determines that stagnant paper 752, 753, 754, and 755 are to be transported to the retraction section 90 and transports them to the retraction section 90 as described below.

[0058] In step S11, the CPU 111 generates data for the counter N of the number of sheets remaining in the machine in RAM 112, and in step S12, it executes a loop process by repeating this until counter N becomes 0. That is, in this loop process, after each process, the data for counter N is decremented by -1 in step S16, and in step S12, it is determined that counter N > 0, and the processing for N sheets is executed. Following the example in Figure 9, when the remaining sheet 751 is processed, counter N = 5; with remaining sheet 752, counter N = 4; with remaining sheet 753, counter N = 3; with remaining sheet 754, counter N = 2; and with remaining sheet 755, counter N = 1. When the processing of remaining sheet 755 is completed, counter N = 0 (N in S12), and the loop process ends.

[0059] In detail, first, in this example, the counter for the number of sheets of paper that are stuck is set to N=5 according to the number of sheets of paper that are stuck as shown in Figure 9, and data for the counter for the number of sheets to be saved is also generated in RAM112, and the initial value of this counter for the number of sheets to be saved is set to 0 (S11). In step S12, the CPU111 determines that there are sheets of paper to be processed because N>0 (Y in S12), and executes the loop process.

[0060] In step S13, the CPU 111 determines, based on the judgment conditions in the example of Figure 9 as described above, whether the paper is to be moved to the retraction section 90 or not. If the CPU 111 determines that the paper is to be discharged to the retraction section 90 (for example, paper 752, 753, 754, 755 in Figure 9) (Y in S13), it increments the retraction counter M by +1 (S14). On the other hand, if the CPU 111 determines in step S13 that the paper is not to be moved (for example, paper 751 in Figure 9) (N in S13), it stops the paper in place (S15). In the example of Figure 9, paper 751 is stopped by stopping the external discharge roller pair 72 (see Figure 1). Subsequently, in step S16, the retraction counter N is decremented by -1, and the process returns to step S12. In step S12, when the counter N is no longer > 0 and the judgment for all stagnant paper is complete (N in S12), in step S17, it is determined whether the counter for the number of sheets to be evacuated M > 0 (i.e., whether there are any sheets to be evacuated). If the counter for the number of sheets to be evacuated M > 0 and there are stagnant papers to be evacuated, the process proceeds to step S21 in Figure 6. If there are no stagnant papers to be evacuated, the process proceeds to step S18 and the discharge process ends.

[0061] As described above, by executing the flowchart shown in Figure 5, the counter M for the number of sheets to be evacuated is set, and thus the control of the sheet count determination operation is completed. Once the control of the sheet count determination operation in Figure 5 is completed, the control of the sheet discharge operation, which discharges the sheets shown in Figure 6 into the evacuation unit 90, is initiated.

[0062] As shown in Figure 6, when the CPU 111 proceeds to step S21, it first turns off the reversing / double-sided flapper solenoid 95. That is, in order to transport the stagnant paper to be retracted to the retraction section 90 via the reversing unit 50, it switches the flapper 73 so that the destination is the transport path 75. Next, in step S22, it drives the reversing / double-sided drive motor 93 in CW mode to rotate the first reversing / double-sided roller pair 51A and the second reversing / double-sided roller pair 51B (S22). Although not shown in Figure 6, the reversing pull-in drive motor 99 is also driven in CW mode to rotate the reversing pull-in roller pair 55. This starts the transport of the stagnant paper in the direction of the reversing unit 50 (S23).

[0063] Next, the system waits until the inversion / double-sided transport guide sensor 92 is turned ON (N in S24). When the inversion / double-sided transport guide sensor 92 is turned ON (Y in S24), it is determined whether the paper that caused the inversion / double-sided transport guide sensor 92 to turn ON is the last sheet of paper (S25). In other words, it is determined whether the counter M for the number of sheets to be evacuated is 1. If the paper that caused the inversion / double-sided transport guide sensor 92 to turn ON is not the last sheet of paper (N in S25), the paper is discharged to the evacuation unit 90 (S26), and the counter M for the number of sheets to be evacuated is decremented by -1 (S27). For example, in the example in Figure 9, if the paper sheets 752, 753, and 754 are transported to the first detection position 92A of the inversion / double-sided transport guide sensor 92, these paper sheets 752, 753, and 754 are not the last sheets of paper, so they are discharged to the evacuation unit 90. Then, it is determined whether or not there are still any stagnant papers remaining, that is, whether or not the counter M for the number of sheets to be evacuated is greater than 0 (S28). If there are still stagnant papers remaining (N in S28), the process returns to step S21 above.

[0064] On the other hand, in step S25, if the paper that has been turned ON by the inversion / double-sided transport guide sensor 92 is the last sheet of paper (Y in S25), the inversion / double-sided drive motor 93 is stopped, and the first inversion / double-sided roller pair 51A and the second inversion / double-sided roller pair 51B are stopped. In other words, for example in the example in Figure 9, if the paper that has been left behind 755 is transported to a position (detection position) that can be detected by the first detection position 92A of the inversion / double-sided transport guide sensor 92, then this paper that has been left behind 755 is the last sheet of paper, so the inversion / double-sided drive motor 93 is stopped, and its transport is stopped. Then the paper discharge process described above is terminated. As a result, the paper discharge process is terminated with the paper that has been left behind 755 remaining at the first detection position 92A of the inversion / double-sided transport guide sensor 92 (state in Figure 8(d)).

[0065] As a result of the above discharge process, the discharge process (S3) shown in Figure 4 ends with the last remaining sheet of paper, the stagnant paper 755, remaining at the first detection position 92A of the inversion / double-sided transport guide sensor 92. At this time, the CPU 111 can detect the stagnant paper 755 using the inversion / double-sided transport guide sensor 92, and in response to this detection, displays a screen as shown in Figure 10 on the operation unit 105. In other words, it notifies the user to remove the stagnant paper 752-754 discharged to the retraction unit 90 and the stagnant paper 755 remaining in the inversion unit 50 (S4). The user will remove the stagnant paper by looking at the display in Figure 10.

[0066] <Paper movement processing> Next, the paper movement process according to the first embodiment will be explained using Figure 7. Figure 7 is a flowchart of the paper movement process according to the first embodiment.

[0067] As described above, a paper jam occurs during printing (Y in S1), and after the discharge process (S3) in which the accumulated paper is discharged to the retraction unit 90 is completed, the display shown in Figure 10 is displayed on the operation unit 105 (S4). Then, the CPU 111 starts the paper movement process as the sheet movement mode shown in Figure 7. First, the CPU 111 starts monitoring the change in the open / closed state of the door 120 based on the detection result of the door sensor 121, and waits until it detects that the door 120 is open (N in S31). When the door 120 is opened by the user and the door sensor 121 detects that it is open (Y in S31), it waits until it detects that the door 120 is closed (N in S32). Then, when the door 120 is closed by the user and the door sensor 121 detects that it is closed (Y in S32), the process proceeds to step S33.

[0068] In other words, it is assumed that the user opens the door 120 to remove the remaining paper, which is the final sheet, from the retraction section 90 and the reversal / double-sided transport guide sensor 92. Detection of the door 120 being closed is input to the CPU 111 as a trigger for the user to finish removing the remaining paper and for the image forming apparatus 100 to recover from the paper jam state.

[0069] Next, the CPU 111 determines whether the inversion / double-sided transport guide sensor 92 is ON or OFF when the door 120 is closed (S33). If the user has removed the retained paper from the inversion / double-sided transport guide sensor 92 along with the retained paper loaded in the retraction unit 90, the inversion / double-sided transport guide sensor 92 will be OFF (N in S33). In this case, the retained paper from the time of the paper jam is considered to have been removed, and the paper jam indicator displayed on the operation unit 105 (see Figure 10) is cleared, completing the clearing of the paper jam (S37), and the paper transfer process is terminated.

[0070] On the other hand, if the user does not notice the retained paper in the inversion / double-sided transport guide sensor 92 and only removes the retained paper loaded in the retraction section 90, the retained paper will remain in a position detectable by the first detection position 92A of the inversion / double-sided transport guide sensor 92. In other words, the retained paper in a position detectable by the inversion / double-sided transport guide sensor 92 (detection position) is likely to be of a size that is difficult for the user to see even when the door 120 is opened. In this case, the inversion / double-sided transport guide sensor 92 will turn ON (Y in S33).

[0071] In this case, the reversal / double-sided drive motor 93 is driven so that the jammed paper moves a predetermined distance (S34). Through this operation, the CPU 111 discharges the last jammed paper, which is in a position detectable by the reversal / double-sided transport guide sensor 92, to the retraction section 90, that is, moves the jammed paper to a position that is easily noticeable to the user. Here, since the paper jam indicator displayed on the operation unit 105 has not been cleared, the CPU 111 waits until it detects the door 120 to be open again (N in S35). When the door 120 is opened by the user and the door sensor 121 detects the open state (Y in S35), the CPU 111 waits until it detects the door 120 to be closed again (N in S36). Then, when the door 120 is closed by the user and the door sensor 121 detects the closed state (Y in S36), the process proceeds to step S37. In other words, when the door 120 is opened and closed in this manner, the last remaining sheet of paper is discharged into the retraction section 90, and the user should have noticed and removed it. Therefore, it is determined that the user has completed removing the remaining paper, and the paper jam indicator displayed on the operation unit 105 (see Figure 10) is cleared, completing the clearing of the paper jam (S37), and the paper transfer process is terminated.

[0072] According to the first embodiment described above, even without a sensor to detect the presence or absence of retained paper in the retraction section 90, it is possible to notify the user of the removal of retained paper from the retraction section 90 by leaving the retained paper in a position detectable by the reversal / double-sided transport guide sensor 92. As a result, when the paper jam is released with retained paper remaining in the retraction section 90, and the user resumes the job, it is possible to prevent another paper jam caused by the next transported paper hitting the retained paper in the retraction section 90.

[0073] Furthermore, in this first embodiment, even if the last sheet of paper remains in the device as the opening and closing state of the door 120 changes, the last sheet of paper is discharged into the retraction section 90, making it easier for the user to find it. In other words, by moving the paper that was in a position that would not be noticed during the initial opening and closing of the door 120 to the retraction section 90, which is easily visible to the user, the user can easily remove the paper. In this way, even with a configuration in which the retraction section 90 does not have a sensor to detect the sheet and the last sheet of paper remains inside the device, the usability of the paper removal process can be improved.

[0074] <Second Embodiment> Next, a second embodiment, which is a modified version of the first embodiment described above, will be explained using Figure 11. Figure 11 is a flowchart of the paper movement process according to the second embodiment.

[0075] In the first embodiment described above, after the discharge process was completed and the door 120 was opened and closed, if retained paper was detected by the reversal / double-sided transport guide sensor 92, the retained paper was moved to the retraction section 90 and discharged, and the door 120 was opened and closed again by the user. In this second embodiment, when the door 120 is opened for the first time after the discharge process is completed, the last remaining paper is moved to the retraction section 90 and discharged.

[0076] In detail, when the CPU 111 starts the paper transfer process shown in Figure 11, it starts monitoring the change in the open / closed state of the door 120 based on the detection result of the door sensor 121, and waits until it detects that the door 120 is open (N in S131). When the door 120 is opened by the user and the door sensor 121 detects that it is open (Y in S131), the process proceeds to step S132.

[0077] Next, the CPU 111 determines whether the reversal / double-sided transport guide sensor 92 is ON or OFF when the door 120 is open (S132). If the reversal / double-sided transport guide sensor 92 is OFF (N in S132), there is no paper remaining, so in this case the process proceeds directly to step S134.

[0078] On the other hand, if the inversion / double-sided transport guide sensor 92 is ON (Y in S132), the stagnant paper remains at the position (detection position) that can be detected by the first detection position 92A of the inversion / double-sided transport guide sensor 92. In this case, the inversion / double-sided drive motor 93 is driven to move the stagnant paper a predetermined distance (S133). Through this operation, the CPU 111 discharges the stagnant paper of the final sheet, which is at the detection position of the inversion / double-sided transport guide sensor 92, to the retraction unit 90, that is, moves the stagnant paper to a position that is easily noticeable to the user. As a result, the user can remove the stagnant paper of the final sheet at the same time as the stagnant paper already loaded in the retraction unit 90.

[0079] Subsequently, the CPU 111 waits until it detects that the door 120 is closed (N in S134). When the door 120 is closed by the user and the door sensor 121 detects that it is closed (Y in S134), the process proceeds to step S135. That is, if the door 120 is closed in this way, the last remaining sheet of paper has been discharged into the retraction unit 90 and the user should have noticed and removed it. Therefore, the CPU determines that the user has completed removing the remaining paper, clears the paper jam indicator displayed on the operation unit 105 (see Figure 10), completes the clearing of the paper jam (S135), and terminates this paper transfer process.

[0080] As described above, according to this second embodiment, when the door 120 is opened for the first time after the discharge process is completed, the last remaining paper is moved to the retraction section 90 and discharged, eliminating the need for the user to open and close the door 120 twice. This further improves the usability of the user's work in removing the remaining paper.

[0081] Furthermore, the configuration, operation, and effects of this second embodiment are the same as those of the first embodiment described above, so their explanation will be omitted.

[0082] <Third Embodiment> Next, a third embodiment, which is a modified version of the first embodiment described above, will be explained using Figures 12 and 13. Figure 12 is a flowchart of the paper movement process according to the third embodiment. Figure 13(a) is a diagram showing the position of the final sheet at the end of the discharge process according to the third embodiment. Figure 13(b) is a diagram showing the movement of the final sheet during the final sheet movement control according to the third embodiment. And Figure 13(c) is a diagram showing the completion of the movement of the final sheet by the final sheet movement control according to the third embodiment.

[0083] In the first embodiment described above, after the discharge process was completed and the door 120 was prompted to be opened and closed, if the last remaining sheet of paper was detected by the inversion / double-sided transport guide sensor 92, the remaining sheet of paper was moved to the retraction section 90 and discharged. In this third embodiment, after the door 120 was prompted to be opened and closed, if the last remaining sheet of paper was detected by the inversion / double-sided transport guide sensor 92, the remaining sheet of paper was inverted and transported to a position where it could be easily found and removed by the user.

[0084] In detail, when the CPU 111 starts the paper transfer process shown in Figure 12, it starts monitoring the change in the open / closed state of the door 120 based on the detection result of the door sensor 121, and waits until it detects that the door 120 is in an open state (N in S231). When the door 120 is opened by the user and the door sensor 121 detects that it is in an open state (Y in S231), it waits until it detects that the door 120 is in a closed state (N in S232). Then, when the door 120 is closed by the user and the door sensor 121 detects that it is in a closed state (Y in S232), it proceeds to step S233.

[0085] Next, the CPU 111 determines whether the inversion / double-sided transport guide sensor 92 is ON or OFF when the door 120 is closed (S233). If the user has removed the retained paper from the inversion / double-sided transport guide sensor 92 along with the retained paper loaded in the retraction unit 90, the inversion / double-sided transport guide sensor 92 will be OFF (N in S233). In this case, the retained paper from the time of the paper jam is considered to have been removed, and the paper jam indicator displayed on the operation unit 105 (see Figure 10) is cleared to complete the clearing of the paper jam (S241), and the paper transfer process is terminated.

[0086] On the other hand, suppose the user did not notice the stagnant paper that was located at a position detectable by the reversal / double-sided transport guide sensor 92 (hereinafter referred to as "first position P1" (see Figure 13(a))). In this case, if only the stagnant paper loaded in the retraction section 90 is removed, the stagnant paper remains at the first position P1 detectable by the first detection position 92A of the reversal / double-sided transport guide sensor 92. In other words, it is highly likely that the stagnant paper at the first position P1 was of a size that would be difficult for the user to see even when the door 120 is opened. Then the reversal / double-sided transport guide sensor 92 turns ON (Y in S233).

[0087] In this case, first, the reversing / double-sided flapper solenoid 95 is turned ON (S234), and the reversing / double-sided flapper 54 is switched so that the transport path 52 and the transport path 62 are connected. Next, the reversing / double-sided drive motor 93 is started to drive in CCW mode (S235). As a result, the paper remaining at the first position P1 is transported toward the double-sided transport unit 60 by the first reversing / double-sided roller pair 51A and the second reversing / double-sided roller pair 52A.

[0088] Next, with the reversing / double-sided drive motor 93 still running, the system waits until the reversing / double-sided sensor 91 turns ON (N in S236). Once the reversing / double-sided sensor 91 turns ON (Y in S236), the reversing / double-sided drive motor 93 is stopped (S237). This causes the CPU 111 to move the stagnant paper from the first position P1 to a position where it can be detected by the second detection position 91A of the reversing / double-sided sensor 91 (hereinafter referred to as "second position P2" (see Figure 13(c))), thereby moving the stagnant paper to a position easily noticeable to the user. It is preferable to stop the reversing / double-sided drive motor 93 after a predetermined time has elapsed since the reversing / double-sided sensor 91 detected the stagnant paper. In other words, the stagnant paper is moved in such a way that the trailing end of the stagnant paper, which is reversed and transported in the second direction, does not pass through the second detection position 91A, and as much of the stagnant paper as possible enters the transport path 62, thereby moving the stagnant paper to a position easily noticeable to the user.

[0089] Next, the CPU 111 waits until it detects the door 120 to be open again (N in S238). When the door 120 is opened by the user and the door sensor 121 detects the open state (Y in S238), the CPU waits until it detects the door 120 to be closed again (N in S239). Then, when the door 120 is closed by the user and the door sensor 121 detects the closed state (Y in S239), the process proceeds to step S240.

[0090] Then, it is determined whether the inversion / double-sided sensor 91 is OFF or OFF (S240). If the inversion / double-sided sensor 91 is ON (N in S240), the retained paper that has moved to the second position P2 has not been removed, so the process returns to step S238. The process then waits until the door 120 is opened or closed. After that, if the inversion / double-sided sensor 91 turns OFF (Y in S240), it is determined that the user has completed removing the retained paper. As a result, the paper jam indicator displayed on the operation unit 105 (see Figure 10) is cleared, the paper jam is cleared (S241), and the paper movement process ends.

[0091] (Movement of stagnant paper in the paper transfer process in the third embodiment) Next, the movement of the stagnant paper in the paper transfer process in the third embodiment will be explained using Figure 13. As shown in Figure 13(a), when the discharge process in step S3 is completed, the stagnant paper Pt (stagnant paper 755 in Figure 9) is stopped at a first position P1 that can be detected by the first detection position 92A of the reversal / double-sided transport guide sensor 92 in the transport path 52. In this state, the door 120 is opened and then closed (S231~S233). Then, as shown in Figure 13(b), the stagnant paper Pt is transported toward the transport path 62 of the double-sided transport unit 60 by the first reversal / double-sided roller pair 51A and the second reversal / double-sided roller pair 51B (S234~S235).

[0092] Furthermore, when the stagnant paper Pt is transported, it passes through the second detection position 91A of the inversion / double-sided sensor 91 and is turned ON (Y in S236). After passing the inversion / double-sided sensor 91, the inversion / double-sided drive motor 93 is stopped before the stagnant paper Pt leaves the inversion / double-sided sensor 91 (S237), causing the stagnant paper Pt to stop at the second position P2 shown in Figure 13(c). When the user opens the door 120, the stagnant paper Pt is in the transport path 62, which is above the retraction section 90, making it easy to find and remove the stagnant paper Pt. It is desirable that the second position P2 of the stagnant paper Pt be at a position where it can be accessed by opening the door 120, so as to be the same as the door that opens and closes the retraction section 90, which was opened initially. In addition, this transport path 62 is configured so that upper or lower guide members can be opened by operating levers, etc. (not shown), allowing the paper to be removed when a paper jam occurs. Therefore, the design makes it easy to remove the accumulated paper Pt by opening the guide member, similar to how it would be done when there is a paper jam.

[0093] Thus, according to this third embodiment, after the discharge process is completed and the door 120 is opened and closed for the first time, the last remaining paper is moved to the transport path 62 above the retraction section 90. This makes it easier for the user to find and remove the paper by opening the door 120 again. Therefore, the usability of the user's work in removing the remaining paper can be further improved.

[0094] Furthermore, the configuration, operation, and effects of this third embodiment are the same as those of the first embodiment described above, so their explanation will be omitted.

[0095] [Possibility of other embodiments] In the first to third embodiments described above, the door sensor 121 was described in which the open or closed state of the door 120 was detected. The closed state of the door 120 is the state in which the door 120 is closed so as to form part of the exterior of the image forming apparatus 100, and the open state can be understood as any state other than the closed state. However, since it is not possible to remove retained paper in the half-open state, the door sensor 121 may be configured to detect the state of the door 120 with high precision, and the open state may be detected as either a fully open state or a state in which the paper can be removed. In this case, it is conceivable to use an angle sensor such as an encoder as the door sensor.

[0096] Furthermore, in the third embodiment, after the discharge process is completed, the door 120 is opened and then closed before the retained paper is moved. However, the invention is not limited to this, and, as in the second embodiment, the retained paper may be moved in response to the opening of the door 120.

[0097] Furthermore, in the first to third embodiments, when the transport path 74 is unavailable, the accumulated paper is discharged to the retraction section 90, which retracts the paper to be reversed by the reversing unit 50. However, the invention is not limited to this, and the discharge process of this embodiment can be performed similarly in any case where there are multiple destinations for paper discharge, such as when there are multiple discharge trays, and when one transport path is unavailable, the other available transport path is used for discharge.

[0098] Furthermore, in the first to third embodiments, the sheet was described as paper or retaining paper, but the type of sheet can be anything and is not limited to paper as a material.

[0099] Furthermore, although the image forming apparatus described in the first to third embodiments was a full-color electrophotographic type, it is not limited to this, and any type of image forming apparatus is acceptable, such as a monochrome printer or inkjet printer. In addition, although the discharge and loading sections were described as being provided in the image forming apparatus, the discharge and loading sections may also be provided in processing devices such as finishers, hole punchers, binding devices, and folding devices. In this case, it can be considered an image forming apparatus equipped with processing devices.

[0100] This disclosure can also be implemented by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of Symbols]

[0101] 50...Reversing unit (sheet transport section, reversing section) / 52...Transport path (second transport path) / 53...Discharge flapper (third branch section) / 54...Double-sided flapper (second branch section) / 62...Transport path (third transport path) / 72...External discharge roller (discharge section) / 73...Flapper (first branch section) / 74...Transport path (first transport path) / 75...Transport path (second transport path) / 76...Transport path (fourth transport path) / 90...Retraction section (loading section) / 91...Reversing / double-sided sensor S (Second Sheet Detection Unit) / 92... Reversal / Double-Sided Transport Guide Sensor (Sheet Detection Unit, First Sheet Detection Unit) / 100... Image Forming Apparatus / 100A... Image Forming Unit / 105... Operation Unit (Display Unit) / 111... CPU (Control Unit) / 120... Door (Opening / Closing Unit) / 121... Door Sensor (Opening / Closing Detection Unit) / A... First Direction / B... Second Direction / P... Paper (Sheet) / P1... First Position / P2... Second Position / S3... Discharge Processing (Separate Discharge Mode)

Claims

1. an image forming unit that forms an image on a sheet; a discharge section that discharges a sheet on which an image has been formed by the image forming section to the outside; a first conveying path that conveys a sheet on which an image is formed by the image forming unit to the discharge unit; a second conveying path branched off from the first conveying path at a first branching portion; a sheet conveying unit that conveys the sheet in the second conveying path; a stacking section for stacking the sheets discharged from the second conveying path; an opening / closing unit that opens and closes between a closed state that covers the loading unit and an open state that opens the loading unit; a sheet detection unit that detects a sheet at a detection position of the second transport path; an open / close detection unit that detects an open / close state of the open / close unit; a control unit that executes a separate discharge mode in which a plurality of sheets inside the device are discharged to the stacking unit when a paper jam occurs during sheet conveyance, and ends the separate discharge mode in a state in which the sheets are left at the detection position, and after the separate discharge mode is terminated, the control unit executes a sheet movement mode in which the sheet conveying unit discharges the sheet at the detection position to the stacking unit in response to detection of a change in the open / close state of the opening / closing unit by the opening / closing detection unit.

1. An image forming apparatus comprising:

2. and in the sheet movement mode, the control unit detects an open state of the opening / closing unit by the opening / closing detection unit, and then, in response to detecting a closed state of the opening / closing unit by the opening / closing detection unit and detecting a sheet at a detection position of the second transport path by the sheet detection unit, discharges the sheet at the detection position to the stacking unit.

2. The image forming apparatus according to claim 1,

3. the control unit, in the sheet movement mode, after discharging the sheet at the detection position to the stacking unit, detects an open state of the opening / closing unit by the opening / closing detection unit, and then ends the sheet movement mode in response to detection of a closed state of the opening / closing unit by the opening / closing detection unit.

3. The image forming apparatus according to claim 2,

4. the control unit, in the sheet movement mode, detects an open state of the opening / closing unit by the opening / closing detection unit, and in response to detection of a sheet at a detection position on the second transport path by the sheet detection unit, discharges the sheet at the detection position to the stacking unit.

2. The image forming apparatus according to claim 1,

5. the control unit, in the sheet movement mode, discharges the sheet at the detection position onto the stacking unit, and then ends the sheet movement mode in response to detection by the open / close detection unit of a closed state of the open / close unit.

5. The image forming apparatus according to claim 4.

6. a reversing unit that is disposed on the second conveying path, conveys the sheet on which the image is formed by the image forming unit in a first direction, and then conveys the sheet in a second direction opposite to the first direction, thereby reversing the sheet; the sheet conveying unit is the inversion unit, the stacking unit is a retracting unit that retracts a leading end of the sheet in the first direction to be inverted by the inverting unit, 6. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises:

7. a third transport path that branches off from the second transport path at a second branching portion and transports the sheet that has been inverted by the inverting portion back to the image forming portion; 7. The image forming apparatus according to claim 6,

8. a fourth conveying path that branches off from the second conveying path at a third branching portion and conveys the sheet that has been inverted by the inverting portion to the discharge portion; the inverting unit is disposed downstream of the third branching unit in the first direction and is capable of transporting the sheet in the second direction to the fourth transport path; 8. The image forming apparatus according to claim 7,

9. A display unit for displaying an image is provided, and after the separate discharge mode is stopped, in response to detection of the sheet by the sheet detection unit, the control unit causes the display unit to display a message prompting the user to remove the sheets stacked on the stacking unit.

9. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises:

10. an image forming unit that forms an image on a sheet; a discharge section that discharges a sheet on which an image has been formed by the image forming section to the outside; a first conveying path that conveys a sheet on which an image is formed by the image forming unit to the discharge unit; a second conveying path branched off from the first conveying path at a first branching portion; an inversion unit that is disposed on the second transport path and transports the sheet on which the image is formed by the image forming unit in a first direction, and then inverts the sheet by transporting the sheet in a second direction opposite to the first direction; a stacking section that stacks sheets that have been transported from the second transport path in the first direction and discharged; an opening / closing unit that opens and closes between a closed state that covers the loading unit and an open state that opens the loading unit; a first sheet detection unit that detects a sheet located at a first position of the second transport path; a second sheet detection unit that detects a sheet that is at a second position in the second direction relative to the first position; an open / close detection unit that detects an open / close state of the open / close unit; a control unit that executes a separate discharge mode in which a plurality of sheets inside the device are discharged to the stacking unit when a paper jam occurs during sheet conveyance, and ends the separate discharge mode in a state in which the sheets are left at the first position, the control unit, after the end of the separate discharge mode, executes a sheet movement mode in which the sheet at the first position is transported to the second position by the inversion unit in response to detection of a change in the open / close state of the opening / closing unit by the opening / closing detection unit.

1. An image forming apparatus comprising:

11. and in the sheet movement mode, after the open / close detection unit detects an open state of the open / close unit, the control unit conveys the sheet at the first position to the second position in response to the open / close detection unit detecting a closed state of the open / close unit and the first sheet detection unit detecting a sheet at a detection position of the second transport path.

11. The image forming apparatus according to claim 10.

12. the control unit, in the sheet movement mode, after conveying the sheet at the first position to the second position, detects an open state of the opening / closing unit by the opening / closing detection unit, and then ends the sheet movement mode in response to detection of a closed state of the opening / closing unit by the opening / closing detection unit.

12. The image forming apparatus according to claim 11.

13. The second position is a position in which the opening / closing unit is covered in the closed state and is opened in the open state.

13. The image forming apparatus according to claim 10, wherein the image forming apparatus comprises: a first fixing unit;

14. a third conveying path that branches off from the second conveying path at a second branching portion and conveys the sheet that has been inverted by the inverting portion back to the image forming portion; the control unit, in the sheet movement mode, transports a leading edge of the sheet from the first position to the second position, to the third transport path.

14. The image forming apparatus according to claim 10, wherein the image forming apparatus comprises:

15. The third transport path is disposed above the stacking unit.

15. The image forming apparatus according to claim 14.

16. a fourth conveying path that branches off from the second conveying path at a third branching portion and conveys the sheet that has been inverted by the inverting portion to the discharge portion; the inverting unit is disposed downstream of the third branching unit in the first direction and is capable of transporting the sheet in the second direction to the fourth transport path; 16. The image forming apparatus according to claim 14,

17. the stacking unit is a retracting unit that retracts a leading end of the sheet in the first direction to be inverted by the inverting unit, 17. The image forming apparatus according to claim 10, wherein the image forming apparatus comprises:

18. A display unit for displaying an image is provided, and after the separate discharge mode is stopped, in response to detection of a sheet by the first sheet detection unit, the control unit causes the display unit to display a message prompting the user to remove the sheets stacked on the stacking unit.

18. The image forming apparatus according to claim 10, wherein the image forming apparatus comprises:

19. When the discharge unit is unavailable and the second conveying path is available, the control unit executes the separate discharge mode.

19. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises:

Images