Image forming device

Abstract

To provide an image-forming device improving jam processing characteristics.SOLUTION: An image-forming device includes a conveyance unit conveying a sheet in a conveyance direction, an image carrier, a transfer unit forming a transfer nip along with the image carrier, a fixing unit fixing a toner image to a sheet in the fixing nip, a discharging unit discharging a sheet, a detection unit that is disposed between the fixing nip and the discharge unit in a conveyance direction and detects a sheet, and a control unit that controls the conveyance unit and the image carrier and controls conveyance of a sheet. The control unit executes conveyance processing conveying a jam sheet by the conveyance unit and the image carrier such that a rear end of the jammed jam sheet travels downstream from the transfer nip in a conveyance direction when determining occurrence of a jam downstream from the fixing nip in a conveyance direction on the basis of a detection result of the detection unit.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] In general, in an image forming apparatus using electrophotography, if a transport failure such as a sheet jam occurs during image formation, the image formation is immediately interrupted. At this time, the image forming apparatus stops all controls related to printing such as sheet transport, image drawing, developing, transfer, and fixing processes.

[0003] Conventionally, an image forming apparatus equipped with a pair of registration rollers that feeds a sheet toward a transfer unit that transfers a toner image on a photoreceptor to the sheet has been disclosed (see Patent Document 1). In this image forming apparatus, when a jam occurs with a sheet sandwiched between the pair of registration rollers, the pair of registration rollers are driven to rotate forward or backward, and are controlled to forcibly separate the jammed sheet from the nip of the pair of registration rollers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-227985 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus with improved jamming disposal capabilities. [Means for solving the problem]

[0006] The present invention provides an image forming apparatus including a conveying unit that conveys a sheet in a conveying direction, an image carrier that carries a toner image, and a transfer section that forms a transfer nip with the image carrier and transfers the toner image on the image carrier to the sheet conveyed by the conveying unit at the transfer nip; The fixing device includes a first rotating body and a second rotating body that are each configured to be rotatable and that come into contact with each other to form a fixing nip, The toner image transferred to the sheet at the transfer nip is The above a fixing section that fixes the toner image on the sheet at a fixing nip, a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section, a detection section that is disposed between the fixing nip and the discharge section in the transport direction and detects the sheet, and a control section that controls the transport unit and the image carrier to control transport of the sheet. And When it is determined that a jam has occurred based on the detection result of the detection unit, a conveying process is performed to convey the jammed sheet so that the trailing end of the jammed sheet detected by the detection unit moves downstream of the transfer nip in the conveying direction. Control unit and , a conveying guide having a guide surface that guides a sheet downstream of the fixing nip in the conveying direction; and a pressed member that is movably supported by the conveying guide and that moves from a first position away from the first rotating body to a second position closer to the first rotating body than the first position by being pressed by the jammed sheet, and the pressed member abuts against the first rotating body at the second position. It is characterized by: The present invention also provides an image forming apparatus including a transport unit that transports a sheet in a transport direction, an image carrier that carries a toner image, a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier at the transfer nip to a sheet transported by the transport unit, a fixing section that fixes the toner image transferred to the sheet at the transfer nip to the sheet at a fixing nip, and a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section, a detection section that is disposed between the fixing nip and the discharge section in the transport direction and detects the sheet, a control section that controls the transport unit and the image carrier to control transport of the sheet, and a transport path that is disposed downstream of the fixing nip in the transport direction and through which a sheet can pass, and when it is determined that a jam has occurred based on a detection result of the detection section, the control section performs a transport process of transporting the jammed sheet such that a trailing end of the jammed sheet detected by the detection section moves downstream of the transfer nip in the transport direction. and a sensor that detects the movement of the second moving member, wherein when the second protrusion is pressed by the jammed sheet, the second moving member is movable from the second protrusion position to the second retracted position when the first protrusion comes into contact with the sheet. In another aspect of the present invention, the detection unit includes a first movable member having a first protrusion, the first protrusion being movable between a first protrusion position where the first protrusion protrudes toward the conveying path and a first retracted position retracted from the first protrusion position, and configured to be moved from the first protrusion position to the first retracted position when the first protrusion comes into contact with the sheet, and a second movable member having a second protrusion and movable relative to the first movable member, the second protrusion being movable between a second protrusion position where the second protrusion protrudes toward the conveying path and a second retracted position retracted from the second protrusion position, and configured to be moved from the second retracted position to the second protrusion position when the first moving member moves from the first protrusion position to the first retracted position, and The present invention also relates to an image forming apparatus, comprising: a transport unit that transports a sheet in a transport direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier at the transfer nip to the sheet transported by the transport unit; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection section that is disposed between the fixing nip and the discharge section in the transport direction and detects the sheet; and a second detection section that is disposed upstream of the transfer nip in the transport direction and detects the sheet. The control unit is equipped with a second detection unit that detects a jammed sheet, and a control unit that controls the transport unit and the image carrier to control the transport of the sheet, and when it is determined that a jam has occurred based on the detection result of the first detection unit, the control unit executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, and the control unit is characterized in that, in the transport process, if the trailing end of the jammed sheet is located upstream of the second detection unit in the transport direction at the time the jam occurs, the control unit transports the jammed sheet a predetermined transport distance after the second detection unit detects the trailing end. The present invention also provides an image forming apparatus, comprising: a transport unit that transports a sheet in a transport direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier at the transfer nip to a sheet transported by the transport unit; a fixing section that fixes the toner image transferred to the sheet at the transfer nip to the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection section that is disposed between the fixing nip and the discharge section in the transport direction and detects the sheet; and a control unit that controls the image carrier to control the transportation of the sheet, and when it is determined that a jam has occurred based on the detection result of the first detection unit, a control unit that executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, and the control unit is characterized in that, in the transport process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the transport direction at the time the jam occurs, the control unit calculates the transport distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the transport direction based on the detection result of the second detection unit. The present invention also provides an image forming apparatus, comprising: a transport unit that transports a sheet in a transport direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier at the transfer nip to a sheet transported by the transport unit; a fixing section that fixes the toner image transferred to the sheet at the transfer nip to the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection section that is disposed between the fixing nip and the discharge section in the transport direction and detects the sheet; and a control unit that controls the image carrier to control the transportation of the sheet, and when it is determined that a jam has occurred based on the detection result of the first detection unit, a control unit that executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, and the control unit is characterized in that, in the transport process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the transport direction at the time the jam occurs, the control unit calculates the transport distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the transport direction based on the detection result of the second detection unit. Effect of the Invention

[0007] According to the present invention, it is possible to improve jamming disposal performance. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an overall configuration of a printer according to an embodiment of the present invention; [Diagram 2] FIG. [Diagram 3] FIG. 4 is an exploded perspective view showing a first flag, a second flag, and a discharge sensor. [Figure 4] FIG. 4 is a perspective view showing a state in which the first flag, the second flag, and the discharge sensor are assembled together. [Diagram 5]6 is a cross-sectional view showing the fixing device in a state in which a first flag is moved by a sheet. FIG. [Figure 6] FIG. 4 is a cross-sectional view of the fixing device, illustrating a state in which a sheet jam has occurred. [Figure 7] FIG. 4A is a perspective view showing a rotating member located at a separated position, and FIG. 4B is a perspective view showing a rotating member located at a contact position. [Figure 8] FIG. 4A is a diagram for explaining detection timing of the discharge sensor when a sheet is normally conveyed, and FIG. 4B is a diagram for explaining detection timing of the discharge sensor when a jam occurs. [Figure 9] FIG. [Figure 10] 11 is a cross-sectional view showing the position of a leading edge Sa of a sheet when an ejection jam occurs. [Figure 11] 6 is a flowchart showing discharge jam control. [Figure 12] 13 is a cross-sectional view showing a state in which the trailing edge of the sheet is transported to the downstream of the transfer nip by the discharge jam control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Overall structure] Printer 100 as an image forming apparatus is an electrophotographic laser beam printer that forms a monochrome toner image. Fig. 1 is an overall schematic diagram showing printer 100. As shown in Fig. 1, printer 100 has a sheet feeding section 50 that feeds a sheet S, an image forming section 60 that forms an image on the fed sheet S, and a fixing device 200. Sheets S include paper such as paper and envelopes, plastic films such as overhead projector sheets (OHP), cloth, etc.

[0010] When an image formation command is output to the printer 100, an image formation process is started by the image forming unit 60 based on image information input from an external computer or the like connected to the printer 100. The image forming unit 60 has a process cartridge 61 as a developing unit, a laser scanner 8, and a transfer roller 6.

[0011] The process cartridge 61 has a rotatable photosensitive drum 5, a charging roller 7, a developing roller 9, and an exposure member 10 arranged along the photosensitive drum 5, a supply roller 160, and a developing container 170. The developing container 170 has a storage section 170a that stores toner, and rotatably supports an agitating device 180 that agitates the toner in the storage section 170a. The agitating device 180 receives drive from a driving source (not shown) and rotates to supply toner to the supply roller 160. The supply roller 160 then supplies toner to the developing roller 9, which serves as a developing member.

[0012] Further, the developing container 170 is formed with a replenishing port 190 for replenishing toner from the outside. A toner container containing toner can be attached to the replenishing port 190. A user can expose the replenishing port 190 by opening the discharge tray 150 or a lid portion (not shown) provided on the discharge tray 150. Then, the user can refill the developing container 170 with toner by attaching a toner container to the replenishing port 190. At this time, at least a portion of the toner container attached to the replenishing port 190 is exposed to the outside of the printer 100.

[0013] A transfer roller 6 as a transfer section forms a transfer nip T1 together with the photosensitive drum 5. A laser scanner 8 irradiates the photosensitive drum 5 with laser light based on input image information. At this time, the photosensitive drum 5 as an image carrier is pre-charged by a charging roller 7, and an electrostatic latent image is formed on the photosensitive drum 5 by irradiating it with laser light. Thereafter, the electrostatic latent image is developed by a developing roller 9, and a monochrome toner image is formed on the photosensitive drum 5.

[0014] In parallel with the above-mentioned image forming process, a sheet is fed from the sheet feeding section 50. The sheet feeding section 50 includes a feed tray 1 on which the sheets S are stacked, a pickup roller 3, and a pair of separation rollers 51. The feed tray 1 is supported by the housing 100A of the printer 100 so as to be openable and closable, and in the closed state, it constitutes a part of the exterior of the front of the printer 100, and in the open state, the user can access the sheet storage space inside the housing 100A. The feed tray 1 may be configured to slide and be stored in and drawn out from the housing 100A, instead of being configured to rotate. In the present embodiment, the process cartridge 61 is provided detachably to the housing 100A, but may be provided non-detachably to the housing 100A.

[0015] In response to a command for image formation, the pickup roller 3 rotates and feeds the sheets S supported on the feed tray 1 by the pickup roller 3. The sheets S fed by the pickup roller 3 are separated one by one by a separation roller pair 51. Note that instead of the pickup roller 3, the sheets S may be fed by a belt or the like.

[0016] The sheets S separated one by one are transported to the registration roller pair 4, and the leading edge of the sheet S hits the nip of the registration roller pair 4, which is in a stopped state, to correct the skew of the sheet S. The registration roller pair 4 is driven at a predetermined transport timing in accordance with the transfer timing at the transfer nip T1. Then, the toner image on the photosensitive drum 5 is transferred to the sheet S transported by the registration roller pair 4 at the transfer nip T1 by the electrostatic load bias applied to the transfer roller 6. Since the potential of the photosensitive drum 5 varies after transfer, the potential is set to a predetermined value by the exposure member 10, in preparation for charging for the image to be formed on the next sheet.

[0017] The sheet S onto which the toner image has been transferred is applied with a predetermined heat and pressure in a fixing nip 200F formed by a heating unit 13 and a pressure roller 14 of the fixing device 200, so that the toner is melted and fixed (fixed). The sheet that has passed through the fixing device 200 is discharged to the outside of the printer 100 by the discharge section 70, and is stacked on the discharge tray 150.

[0018] The discharge section 70 has a discharge roller 15 driven by a motor M (see FIG. 9), and two driven rollers 16a, 16b that rotate following the discharge roller 15. The discharge section 70 has a function of straightening the sheet S curled in the fixing device 200, since the two driven rollers 16a, 16b form a nip with respect to the discharge roller 15. In the present embodiment, the discharge section 70 has two driven rollers 16a, 16b, but is not limited thereto, and may have, for example, only one driven roller.

[0019] [Configuration of the fixing device] Next, a fixing device 200 according to the present embodiment will be described. Fig. 2 is a cross-sectional view showing the fixing device 200 according to the present embodiment. As shown in Fig. 2, the fixing device 200 as a fixing section has a heating unit 13 and a pressure roller 14. Furthermore, the fixing device 200 has a first flag 21, a second flag 22, a discharge sensor 23, and a conveying guide 26.

[0020] The heating unit 13 for heating the sheet S includes a cylindrical fixing film 17, a heater 18 that is inscribed in the fixing film 17 and heats the fixing film, a heat-resistant holder 19, and a stay 20. The fixing film 17 is, for example, a thin-walled cylindrical plastic film that is highly heat-resistant and highly thermally conductive. The heater 18 is a heating element formed by applying a conductor to an insulating-coated metal base material. The heater 18 generates heat when power is supplied from a power source (not shown). The heater 18 is supported by the holder 19 in a state where it is fitted and fixed in a groove of the holder 19. The fixing film 17 is attached in a manner that covers the outer periphery of the heater 18, the holder 19, and the stay 20, and is capable of rotational movement.

[0021] The heating unit 13 is configured to contact the pressure roller 14 with a predetermined pressure by receiving the force of a pressure spring (not shown) to form a fixing nip 200F. The pressure roller 14 has a core 14a and a heat-resistant elastic layer 14b formed in a roller shape on the outer periphery of the core 14a. Since the heat-resistant elastic layer 14b of the pressure roller 14 has elasticity, a fixing nip 200F having a predetermined width in the conveying direction of the sheet S is formed between the heating unit 13 and the pressure roller 14. The pressure roller 14 is driven to rotate at a predetermined speed by a motor M (see FIG. 9). This rotation of the pressure roller 14 generates a frictional force between the fixing film 17 and the pressure roller 14, and the fixing film 17 is rotated by the pressure roller 14.

[0022] With the pressure roller 14 and the fixing film 17 rotating and the heater 18 generating heat, the sheet S carrying an unfixed toner image is transported to the fixing nip 200F between the fixing film 17 and the pressure roller 14. The sheet S that has reached the fixing nip 200F is transported while being sandwiched between the pressure roller 14 and the fixing film 17. During this process, heat from the heater 18 is applied to the sheet S via the fixing film 17, and the unfixed toner image is heated and pressurized to be fixed to the sheet S.

[0023] The curvatures of the pressure roller 14 and the fixing film 17 are set so that the sheet S that has passed through the fixing nip 200F is separated from the pressure roller 14 and the fixing film 17. The sheet S is transported by the pressure roller 14 and the fixing film 17 downstream in the transport direction CD of the fixing nip 200F.

[0024] A conveying path 42 is disposed downstream of the fixing nip 200F (downstream of the heating unit 13) in the conveying direction CD of the sheet S. The conveying path 42 allows the sheet S to pass through on the downstream side of the heating unit 13 (downstream of the fixing nip 200F) and guides the sheet S toward the discharge section 70. The sheet S is conveyed through the conveying path 42 by the pressure roller 14. The sheet S passing through the conveying path 42 comes into contact with a first flag 21 protruding into the conveying path 42, causing the first flag 21 to rotate. The operation of the first flag 21 will be described in detail later.

[0025] [Details of the sheet detection unit] Next, a sheet detection unit 96 as a detection section that detects the sheet S will be described with reference to Fig. 2 to Fig. 4. Fig. 3 is an exploded perspective view showing the first flag 21, the second flag 22, and the discharge sensor 23. Fig. 4 is a perspective view showing the first flag 21, the second flag 22, and the discharge sensor 23 in an assembled state.

[0026] 2 to 4, the fixing device 200 has a sheet detection unit 96 including a first flag 21, a second flag 22, and a discharge sensor 23. The sheet detection unit 96, which serves as a detection section and a first detection section, is disposed between the fixing nip 200F and the discharge section 70 in the conveying direction CD. The discharge sensor 23, which serves as a sensor, is configured to detect the movement of the second flag 22.

[0027] The second flag 22 serving as the second moving member is configured to be movable relative to the first flag 21. In this embodiment, the second flag 22 is attached to the first flag 21. The first flag 21 serving as the first moving member is movable between a first protruding position (see FIG. 2) described below and a first retracted position (see FIG. 5) retracted from the first protruding position. The second flag 22 is movable between a second protruding position (see FIG. 5) described below and a second retracted position (see FIG. 2) retracted from the second protruding position.

[0028] 3 and 4, the first flag 21 has a first protrusion 21a, a rotation stopper 21b as a support portion, and a shaft 21c. The second flag 22 has a second protrusion 22a, a regulated portion 22b as a supported portion, a detected portion 22c, and a hole 22d. The second flag 22 is attached to the first flag 21 by inserting the shaft 21c into the hole 22d. In the conveying direction CD of the sheet S in the conveying path 42 (see FIG. 2), the second protrusion 22a is disposed upstream of the first protrusion 21a.

[0029] In other words, one of the first flag 21 and the second flag 22 has an engaging portion (shaft portion), and the other of the first flag 21 and the second flag 22 has an engaged portion (hole portion) that engages with the engaging portion. The first flag 21 may have a hole portion, and the second flag 22 may have a shaft portion. Also, both the first flag 21 and the second flag 22 may have a hole portion (engaged portion) that engages with a shaft portion (engaging portion) supported by the transport guide 26.

[0030] The first flag 21 and the second flag 22 are attached to a transport guide 26 of the fixing device 200. Specifically, the shaft portion 21c of the first flag 21 is rotatably supported by the transport guide 26, and the second flag 22 is rotatably supported by the shaft portion 21c. As a result, the first flag 21 and the second flag 22 are supported rotatably (swingably) around the rotation axis RF. In other words, the first flag 21 is rotatable around the rotation axis RF, and the second flag 22 is also rotatable around the rotation axis RF.

[0031] In the present embodiment, the discharge sensor 23 is attached to the conveyance guide 26. The first flag 21, the second flag 22, and the discharge sensor 23 are positioned by the conveyance guide 26, which is a single frame body, thereby improving the positional accuracy of the first flag 21, the second flag 22, and the discharge sensor 23 relative to each other.

[0032] In this embodiment, the discharge sensor 23 is an optical sensor. When the detectable portion 22c of the second flag 22 enters the slit of the discharge sensor 23, the discharge sensor 23 enters a light-shielding state. When the detectable portion 22c retreats from the slit of the discharge sensor 23, the discharge sensor 23 enters a light-transmitting state. When the light-transmitting state and the light-shielding state are switched, a signal output from the discharge sensor 23 changes. Based on this signal change, the control unit 80 (see FIG. 9) detects the movement of the second flag 22. Based on the signal output from the discharge sensor 23, the control unit 80 controls the motor M (see FIG. 9) to drive or stop the conveying unit 87 (see FIG. 9).

[0033] A flag biasing spring 24 is disposed between the first flag 21 and the second flag 22. The flag biasing spring 24 as a biasing member is a torsion coil spring. The shaft portion 21c is inserted into the flag biasing spring 24. One end of the flag biasing spring 24 presses the first flag 21, and the other end of the flag biasing spring 24 presses the second flag 22. That is, the flag biasing spring 24 biases the first flag 21 and the second flag 22. As a result, the restricted portion 22b of the second flag 22 is pressed against the rotation stop portion 21b of the first flag 21, and the rotation stop portion 21b of the first flag 21 and the restricted portion 22b of the second flag 22 come into contact with each other. Then, with the rotation prevention portion 21b and the regulated portion 22b in contact with each other, the first flag 21 moves from the first protruding position to the first retracted position, and the second flag 22 moves integrally with the first flag 21 from the second retracted position to the second protruding position.

[0034] A flag holding spring 25 is attached to the first flag 21. The flag holding spring 25 is a torsion coil spring. A shaft portion 21c is inserted into the flag holding spring 25. One end of the flag holding spring 25 presses the transport guide 26, and the other end of the flag holding spring 25 presses the first flag 21. The flag holding spring 25 generates a biasing force between the first flag 21 and the transport guide 26, thereby holding the position of the first flag 21.

[0035] Further, the first protruding portion 21a of the first flag 21 comes into direct contact with the sheet S. A tip roller 29 is rotatably attached to the tip of the first protruding portion 21a. The tip roller 29 reduces the frictional force acting on the sheet S.

[0036] [Operation of the first and second flags] 2 and 5, the operation of the first flag 21 and the second flag 22 by the sheet S will be described. Fig. 5 is a cross-sectional view showing the fixing device 200 in a state in which the first flag 21 is moved by the sheet S.

[0037] 2, when the first flag 21 is not pressed by the sheet S, the flag holding spring 25 positions the first protruding position where the first protruding portion 21a protrudes toward the conveying path 42. At this time, the second flag 22 is positioned at the second retracted position by the regulated portion 22b of the second flag 22 being pressed against the rotation stopper portion 21b of the first flag 21. When the second flag 22 is in the second retracted position, the second protruding portion 22a retracts from the conveying path 42. In addition, the detected portion 22c of the second flag 22 enters a slit portion of the discharge sensor 23, and the discharge sensor 23 is in a light-shielding state.

[0038] 5, when the sheet S passes through the fixing nip 200F and comes into contact with the first protruding portion 21a of the first flag 21, the first flag 21 moves from the first protruding position to the first retracted position. Specifically, the first protruding portion 21a is pushed by the sheet S conveyed by the fixing nip 200F, and the first flag 21 rotates counterclockwise in FIGS. 2 and 5 about the rotation axis RF. As a result, the first flag 21 moves from the first protruding position to the first retracted position.

[0039] As the first flag 21 rotates counterclockwise and moves from the first protruding position to the first retracted position, the second flag 22 moves from the second retracted position to the second protruding position where the second protruding portion 22a protrudes toward the conveying path 42. Specifically, as the first flag 21 rotates counterclockwise, the second flag 22 also rotates counterclockwise together with the first flag 21. As a result, as shown in FIG. 5, the second flag 22 is located at the second protruding position.

[0040] When the second flag 22 moves from the second retracted position to the second protruding position, the detected portion 22c of the second flag 22 retracts from the slit portion of the discharge sensor 23. As a result, the discharge sensor 23 switches from a light-blocking state to a light-transmitting state, and the output of the discharge sensor 23 (a signal output from the discharge sensor 23) changes. This change in output causes the control unit 80 (see FIG. 9) to detect the leading edge position of the sheet S, and if the leading edge position of the sheet S is not within a predetermined range, it determines that a jam has occurred in the sheet S.

[0041] When the sheet S is normally conveyed and the trailing end of the sheet S passes through the first protruding portion 21a, the first flag 21 biased by the flag holding spring 25 rotates clockwise around the rotation axis RF, and the first flag 21 moves from the first retracted position to the first protruding position. When the first flag 21 moves from the first retracted position to the first protruding position, the second flag 22 also moves from the second protruding position to the second retracted position. As a result, the detected portion 22c blocks the discharge sensor 23, and the discharge sensor 23 switches from the light-transmitting state to the light-blocking state, and the output of the discharge sensor 23 (the signal output from the discharge sensor 23) changes. Due to this change in output, the control unit 80 detects the trailing end position of the sheet S, and if the trailing end position of the sheet S is not within a predetermined range, it determines that the sheet S is jammed.

[0042] [2nd flag behavior when a jam occurs] Next, the behavior of the second flag 22 when a jam occurs after the leading edge of the sheet S passes through the first flag 21 will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the fixing device 200 showing a state in which a jam of the sheet S occurs in the conveying path 42.

[0043] Here, consider a case where it takes time for the conveying unit 87 to stop after a jam occurs downstream of the first flag 21 in the conveying direction CD. In this case, as shown in FIG. 6, for example, the sheet S is folded into an accordion shape because the conveyance of the sheet S continues even after the jam occurs.

[0044] In this embodiment, the second flag 22 can move from the second protruding position to the second retracted position while the first flag 21 is in the first retracted position by the second protruding portion 22a coming into contact with the sheet S. Here, when viewed along the rotation axis RF, the rotation direction of the first flag 21 when moving from the first protruding position to the first retracted position is opposite to the rotation direction of the second flag 22 when moving from the second protruding position to the second retracted position.

[0045] When a jam occurs in the conveying path 42, the sheet S bent in an accordion shape comes into contact with the second protruding portion 22a of the second flag 22 in the second protruding position, and moves the second flag 22 against the biasing force of the flag biasing spring 24. When the sheet S comes into contact with the second protruding portion 22a while the first flag 21 is in the first retracted position and the second flag 22 is in the second protruding position, the second flag 22 moves relative to the first flag 21 from the second protruding position toward the second retracted position. At this time, the second flag 22 rotates in the opposite direction to when the sheet S is being conveyed normally, and the regulated portion 22b moves away from the rotation stopper portion 21b.

[0046] The first flag 21 is in contact with the sheet S and is therefore restricted from moving from the first retracted position to the first protruding position. However, the second flag 22 is configured to be movable from the second protruding position toward the second retracted position relative to the first flag 21. Therefore, when the first flag 21 is in the first retracted position, the second flag 22 can move from the second protruding position to the second retracted position.

[0047] Specifically, when the first flag 21 is in the first retracted position and the second flag 22 is in the second protruding position, the movement of the second flag 22 in the direction from the second retracted position to the second protruding position (counterclockwise in FIG. 5) is restricted by the rotation stopper 21b of the first flag 21. On the other hand, when the first flag 21 is in the first retracted position and the second flag 22 is in the second protruding position, the movement of the second flag 22 in the direction from the second protruding position to the second retracted position (clockwise in FIG. 5) is permitted. Therefore, even when the first flag 21 is in the first retracted position by being pushed by the sheet S, the second protruding portion 22a is pushed by the sheet S, so that the second flag 22 can move from the second protruding position to the second retracted position.

[0048] The biasing force of the flag biasing spring 24 is large enough that when the first flag 21 moves from the first protruding position to the first retracted position, the second flag 22 can move from the second retracted position to the second protruding position together with the first flag 21. Furthermore, it is desirable that the biasing force of the flag biasing spring 24 is large enough that the second flag 22 can move relative to the first flag 21 against the biasing force of the flag biasing spring 24 even with the sheet S that has the weakest rigidity among the sheets S that can be used in the printer 100.

[0049] As described above, when a jam occurs in the conveying path 42, the second flag 22 rotates about the rotation axis RF while the first flag 21 is in the first protruding position, and the second flag 22 can rotate from the second protruding position toward the second retracted position. As a result, the detected portion 22c blocks the discharge sensor 23, and the discharge sensor 23 switches from the light-transmitting state to the light-blocking state, and the output of the discharge sensor 23 (the signal output from the discharge sensor 23) changes. In other words, when the sheet S is being conveyed normally, the discharge sensor 23 switches from the light-transmitting state to the light-blocking state before the rear end of the sheet S passes through the first protruding portion 21a.

[0050] That is, the control unit 80 can detect that a transport failure of the sheet S has occurred based on the fact that the discharge sensor 23 reacts at a timing different from the predetermined timing and the output changes.

[0051] 7(a) and (b), a configuration for preventing a jammed sheet from getting between the conveying guide 90 and the fixing film 17 will be described. Fig. 7(a) is a perspective view showing the rotating member 91 located at the separated position, and Fig. 7(b) is a perspective view showing the rotating member 91 located at the abutting position.

[0052] 7(a), a transport guide 90 is provided downstream of the fixing film 17 in the transport direction CD. The transport guide 90 has a guide surface 90a that guides the sheet S. A predetermined gap GP is provided between the guide surface 90a and the fixing film 17, and the fixing film 17 is configured to be able to rotate without contacting the transport guide 90.

[0053] The conveying guide 90 supports a rotating member 91 that can rotate around a rotation axis RG. The rotation axis RG extends in a width direction W that is perpendicular (intersects) with the conveying direction CD. The rotating member 91, which serves as a member to be pressed, is provided in the center of the conveying path 42 (see FIG. 6) in the width direction W. A spring 92 is compressed between the conveying guide 90 and the rotating member 91, and the rotating member 91 is biased by the spring 92 around the rotation axis RG in the direction of the arrow R1. When no external force other than that of the spring 92 is acting on the rotating member 91, the rotating member 91 abuts against the conveying guide 90, thereby being positioned at the separated position shown in FIG. 7(a). At the separated position as the first position, the rotating member 91 is separated from the fixing film 17. The spring 92 may be any type that biases the rotating member 91 in the direction of the arrow R1, and may be a coil spring, a torsion bar, a leaf spring, or the like.

[0054] 6, for example, if the sheet S is bent in an accordion-like shape in the conveying path 42, there is a risk that the sheet S may enter the gap GP between the conveying guide 90 and the fixing film 17. If the sheet S enters the gap GP, damage may occur to the fixing film 17, or a broken piece of the sheet S may remain in the gap GP when the user pulls the jammed sheet S.

[0055] In this embodiment, when the rotating member 91 is pressed against the sheet S bent in an accordion shape in the conveying path 42, the rotating member 91 rotates from the separated position to the contact position against the biasing force of the spring 92, as shown in FIG. Contact At the position where the rotating member 91 is provided, the sheet S abuts against the fixing film 17, and the gap GP can be made as small as possible at the position where the rotating member 91 is provided. This prevents the sheet S from entering the gap GP, and reduces the occurrence of damage to the fixing film 17 and the occurrence of a torn piece of the sheet S remaining in the gap GP when the user pulls the jammed sheet S. In other words, damage to the fixing film 17 can be reduced and jamming can be handled with improved ease.

[0056] The rotating member 91 is preferably a member having high slidability with respect to the fixing film 17, and is formed of, for example, a resin material having a low friction coefficient. In the present embodiment, the rotating member 91 abuts against the fixing film 17 at the abutment position as the second position, but is not limited thereto. For example, the rotating member 91 may be pressed by the jammed sheet S and abut against a stopper (not shown) to rotate to a close position closer to the fixing film 17 than the separated position and separated from the fixing film 17. That is, the rotating member 91 may be pressed by the sheet S to rotate so as to narrow the gap GP compared to when it is located at the separated position. In addition, the rotating member 91 is configured to be rotatable about the rotation axis RG, but is not limited thereto and may be configured to be slidable.

[0057] [Discharge sensor detection timing] Using Figures 8(a) and (b), the difference in detection timing of the discharge sensor 23 depending on the transport state of the sheet S will be described. Figure 8(a) is a diagram explaining the detection timing of the discharge sensor 23 when the sheet S is transported normally, and Figure 8(b) is a diagram explaining the detection timing of the discharge sensor 23 when a jam occurs. The vertical axis of Figures 8(a) and (b) indicates the output of the discharge sensor 23, which is OFF when the discharge sensor 23 is in a light-shielded state and ON when the discharge sensor 23 is in a light-transmitted state. The horizontal axis of Figures 8(a) and (b) indicates time.

[0058] First, when there is no sheet S in the conveying path 42, the signal of the discharge sensor 23 is OFF. When the sheet S normally abuts against the first flag 21, the signal of the discharge sensor 23 is ON. When the conveyance of the sheet S is normal, the signal of the discharge sensor 23 remains ON while the sheet S having a predetermined sheet length passes. After that, when the trailing end of the sheet S passes the first flag 21, the signal of the discharge sensor 23 returns to OFF. The control unit 80 judges whether or not the timing at which the output (signal) of the discharge sensor 23 is switched from ON to OFF is within a predetermined trailing end detection area. If the timing at which the signal is switched from ON to OFF is within the trailing end detection area, the control unit 80 judges that the conveyance of the sheet S is normal. Then, the conveyance of the sheet S is continued. On the other hand, if the timing at which the signal is switched from ON to OFF is outside the trailing end detection area, the control unit 80 judges that a conveyance failure of the sheet S, such as a jam, has occurred.

[0059] The trailing end detection area is determined based on the timing when the trailing end of the sheet S leaves the first protruding portion 21a of the first flag 21, the first flag 21 moves to the first protruding position, and the second flag 21 moves to the second retracted position when the sheet S is normally conveyed. The trailing end detection area is determined in consideration of the sheet length of the sheet S and the variation in conveyance of the sheet S. The control unit 80 acquires the sheet length of the sheet S based on information input by the user via the operation unit 86 (see FIG. 9) and the output of a sensor that detects the size of the sheet S, and sets the trailing end detection area based on the sheet length of the sheet S. The control unit 80 can calculate the trailing end detection area based on the sheet length of the sheet S. The control unit 80 may also set the trailing end detection area by referring to information on the trailing end detection area stored in the storage device of the printer 100. The control unit 80 also determines that a conveyance failure of the sheet S has occurred when the timing when the signal switches from ON to OFF is later than the trailing end detection area.

[0060] Next, a case where the conveyance of the sheet S is not performed normally will be described. Specifically, a case where the sheet S abuts against the first flag 21, the signal of the discharge sensor 23 turns ON, and then the sheet S becomes jammed downstream of the first flag 21 in the conveying direction CD will be described.

[0061] As described above, when the sheet S becomes jammed downstream of the first flag 21 in the conveying direction CD, the sheet S is bent in an accordion shape. Then, the bent sheet S presses the second protruding portion 22a of the second flag 22, and the second flag 22 moves from the second protruding position toward the second retracted position while the first flag 21 is in the first retracted position (see FIG. 6).

[0062] As a result, the second detectable portion 22c blocks the discharge sensor 23, and the signal of the discharge sensor 23 changes from ON to OFF. When the second flag 22 moves to the second retracted position due to the jammed sheet S in this manner, the signal of the discharge sensor 23 switches to OFF at an earlier timing than the trailing end detection area. When the signal of the discharge sensor 23 switches to OFF at an earlier timing than the trailing end detection area, the control unit 80 determines that a jam of the sheet S has occurred.

[0063] [Control Block] Fig. 9 is a control block diagram of the printer 100. As shown in Fig. 9, the printer 100 includes a control unit 80, which has a CPU 81, a ROM 82, a RAM 83, and a timer 84. Various programs are stored in the ROM 82, and the CPU 81 executes the programs stored in the ROM 82. The RAM 83 is used as a work area for the CPU 81. The timer 84 is capable of measuring time.

[0064] A registration sensor 85 and a discharge sensor 23 are connected to the input side of the control unit 80. As shown in FIG. 1, the registration sensor 85 is disposed upstream of the registration roller pair 4 in the conveying direction CD, and is capable of detecting the position of the conveyed sheet S. It can also be said that the registration sensor 85 as a second detection unit is disposed upstream of the transfer nip T1. The registration sensor 85 is composed of, for example, a mechanical sensor having a flag, an optical sensor, or the like. The registration sensor 85 may be disposed downstream of the registration roller pair 4 as long as it is upstream of the transfer nip T1.

[0065] A motor M is connected to the output side of the control unit 80. The motor M drives a conveying unit 87 of the printer 100. The conveying unit 87 includes a pickup roller 3, a pair of separation rollers 51, a pair of registration rollers 4, a photosensitive drum 5, a transfer roller 6, a heating unit 13, a pressure roller 14, and a discharge roller 15. That is, the conveying unit 87 has a function of conveying a sheet S, and the printer 100 of this embodiment drives the conveying unit 87 by one motor M. Among the conveying unit 87, the pickup roller 3, the pair of separation rollers 51, and the pair of registration rollers 4 constitute a conveying unit 99 (see FIG. 1). The conveying unit 99 has a function of further conveying a sheet S that has caused a discharge jam after detecting the discharge jam in a discharge jam control to be described later. Although not included in the conveying unit 99, the photosensitive drum 5 also has a function of further conveying a sheet S that has caused a discharge jam after detecting the discharge jam in a discharge jam control to be described later. The transport unit 99 includes at least the registration roller pair 4, but does not necessarily include the pickup roller 3 and the separation roller pair 51. The registration roller pair 4 is a roller pair immediately before the transfer nip T1 in the transport direction CD.

[0066] In addition, an operation unit 86 where a user performs various settings and inputs is connected to the control unit 80. The control unit 80 constantly performs jam determination of the sheet S based on the detection results of the registration sensor 85 and the discharge sensor 23 and appropriately measures time using a timer 84.

[0067] [Discharge jam control] Next, the discharge jam control in this embodiment will be described with reference to Fig. 10 to Fig. 12. Fig. 10 is a cross-sectional view showing the position of the leading edge Sa of the sheet S when a discharge jam occurs. Fig. 11 is a flowchart showing the discharge jam control. Fig. 12 is a cross-sectional view showing a state in which the trailing edge Sb of the sheet S is conveyed to the downstream of the transfer nip T1 by the discharge jam control.

[0068] The discharge jam control is a control when it is determined that a jam has occurred based on the detection result of the discharge sensor 23. There are various types of jams, and for the sake of convenience, the types of jams are discharge jams, feeding jams, and transfer jams. In this embodiment, a jam that occurs downstream of the fixing nip 200F in the conveying direction CD and is determined based on the detection result of the discharge sensor 23 is called a discharge jam. A jam that is determined based on the leading edge of the sheet S not reaching the registration sensor 85 by a predetermined timing is called a feeding jam. A jam that is determined based on the registration sensor 85 being ON for a predetermined time or more is called a transfer jam.

[0069] 10, when the control unit 80 determines that an ejection jam has occurred, the leading edge Sa of the sheet S may be sticking out of the printer 100 through the ejection outlet 95. The ejection outlet 95 is a space that connects the inside and outside of the printer 100. When the leading edge Sa of the sheet S is outside the printer 100, the user can remove the jammed sheet S by pulling it out of the ejection outlet 95.

[0070] 10, the jammed sheet S is sandwiched between the separation roller pair 51, the registration roller pair 4, and the transfer nip T1. If a user attempts to pull out the sheet S from the discharge port 95 in this state, there is a large resistance to pulling out the sheet S due to the frictional forces of the separation roller pair 51, the registration roller pair 4, and the transfer nip T1.

[0071] Therefore, in this embodiment, discharge jam control is performed as described in the flowchart of Fig. 11. As shown in Fig. 11, first, the control unit 80 judges whether the leading edge Sa of the sheet S is detected by the discharge sensor 23 (step S10). If it is judged that the leading edge Sa of the sheet S is detected by the discharge sensor 23 (step S10: Yes), the control unit 80 judges whether a discharge jam has occurred (step S11). As described above, if the signal of the discharge sensor 23 switches from ON to OFF at a timing earlier or later than the trailing edge detection area, it is judged that a discharge jam has occurred.

[0072] If it is determined that a discharge jam has occurred (step S11: Yes), the control unit 80 controls the motor M so that the conveying unit 87 continues conveying. That is, the control unit 80 continues conveying control (step S12). Next, the control unit 80 determines whether or not a subsequent sheet following the discharge jammed sheet S has caused a feed jam (step S13). If the subsequent sheet has caused a feed jam (step S13: Yes), the control unit 80 stops driving the motor M so as to stop conveying by the conveying unit 87 (step S18).

[0073] On the other hand, if it is determined that the succeeding sheet has not caused a feed jam (step S13: No), the control unit 80 determines whether the trailing end of the sheet S that caused the discharge jam has passed through the registration sensor 85 (step S14). If it is determined that the trailing end of the sheet S has not passed through the registration sensor 85 (step S14: No), the control unit 80 determines whether the registration sensor 85 has been ON for a predetermined time or more (step S15). That is, in step S15, it is checked whether the sheet S is retained so as to keep the registration sensor 85 ON and has caused a transfer jam. Note that the determination of a transfer jam or a jam of a succeeding sheet may be performed before the determination of a discharge jam.

[0074] If it is determined that the registration sensor 85 has been ON for a predetermined time or more (step S15: Yes), the control unit 80 stops driving the motor M so as to stop conveyance by the conveying unit 87 (step S18). If it is determined that the registration sensor 85 has not been ON for a predetermined time or more (step S15: No), the control unit 80 returns to step S12 and continues conveyance control.

[0075] If it is determined in step S14 that the trailing end of the sheet S has passed through the registration sensor 85 (step S14: Yes), the control unit 80 stores the time T at which the registration sensor 85 is turned OFF in the RAM 83 (step S16). Next, the control unit 80 drives the motor M to convey the sheet S by a conveying distance d, which is a predetermined distance from the position of the registration sensor 85, based on the time T (step S17). The conveying distance d is a distance from the position of the registration sensor 85 to a predetermined position downstream of the transfer nip T1. As a result, as shown in FIG. 12, the trailing end Sb of the sheet S, which is a jammed sheet that has caused the discharge jam, is conveyed until it moves downstream of the transfer nip T1 in the conveying direction CD. At this time, the leading end Sa of the sheet S is exposed from the discharge port 95. Then, the control unit 80 stops the motor M to stop driving the conveying unit 87 (step S18), and ends the process.

[0076] In the flow chart of FIG. 11, the case where the trailing end Sb of the sheet S passes the registration sensor 85 in step S14 after the discharge jam occurs in step S11 has been described. This embodiment is not limited to this. For example, in the case of a small-sized sheet, the trailing end Sb of the sheet S may be located downstream of the registration sensor 85 in the conveying direction CD when it is determined that the discharge jam has occurred. In this case, the control unit 80 determines the position of the trailing end Sb of the sheet at the time when the discharge jam occurred from the difference between the time when the trailing end Sb passed the registration sensor 85 and the time when the discharge jam occurred. When it is determined that the trailing end Sb of the sheet S is located upstream of the transfer nip T1, the control unit 80 conveys the sheet from that position to a predetermined position downstream of the transfer nip T1. That is, the control unit 80 determines the conveying distance of the sheet S until the trailing end Sb moves downstream of the transfer nip T1 in the conveying direction CD based on the detection result of the registration sensor 85.

[0077] In the above-described discharge jam control, steps S12, S17, and S18 constitute a conveying process for conveying the jammed sheet S by the conveying unit 99 and the photosensitive drum 5. Then, during the conveying process, if the sheet S causes a transfer jam or if the succeeding sheet following the sheet S causes a feed jam, the conveying of the sheet S is stopped.

[0078] Furthermore, in step S11, if it is determined that no discharge jam has occurred (step S11: No), the control unit 80 determines whether or not printing has finished (step S19). If it is determined that printing has finished (step S19: Yes), the motor M is stopped so as to stop conveyance by the conveyance unit 87 (step S18). If it is determined that printing has not finished (step S19: No), the process returns to step S11.

[0079] As described above, in this embodiment, even if a discharge jam occurs, the motor M is not immediately stopped, and the jammed sheet S is transported until the rear end Sb of the sheet S is located downstream of the transfer nip T1 in the transport direction CD. This prevents the sheet S from being pinched by the separation roller pair 51, the registration roller pair 4, and the transfer nip T1, and reduces the resistance when the user pulls out the sheet S from the discharge port 95. This allows the user to pull out the sheet S with less force, and also reduces the risk of the sheet S being broken when the sheet S is pulled out. This improves jam handling.

[0080] Furthermore, even if a discharge jam occurs, the sheet S may bend in an accordion shape by continuing to convey the sheet S. However, as described in FIGS. 7(a) and 7(b), in this embodiment, a rotating member 91 is provided that is pressed by the jammed sheet S to rotate from the separation position to the contact position. By moving the rotating member 91 to the contact position, it is possible to prevent the sheet S from entering the gap GP between the conveying guide 90 and the fixing film 17 even if the sheet S is bent in an accordion shape in the conveying path 42 (see FIG. 6).

[0081] Furthermore, when the conveyance of the sheet S continues after the occurrence of the discharge jam (steps S12 to S17), if the sheet S causes a transfer jam or the subsequent sheet causes a feed jam, the control unit 80 immediately stops the motor M. Therefore, by continuing the conveyance of the sheet S (step S12), it is possible to prevent other jams from becoming serious, and improve jam clearing performance.

[0082] <Other embodiments> In the present embodiment, the heater 18 of the heating unit 13 directly contacts the fixing film 17 to heat the fixing film 17, but the present invention is not limited to this. For example, the heater 18 may be configured to contact the fixing film 17 via a sheet material having high thermal conductivity, such as an iron alloy or aluminum.

[0083] In the present embodiment, the sheet transport control in the discharge jam control is performed based on the time T when the registration sensor 85 detects the trailing end Sb of the sheet S, but this is not limited to the above. For example, if the sheet length (sheet size) is known in advance by an instruction from the user, the sheet S may be controlled based on the time T12 when the registration sensor 85 detects the leading end Sa of the sheet S. Specifically, the control unit 80 estimates the position of the trailing end Sb of the sheet S at the time when the discharge jam occurred from the time when it is determined that the discharge jam occurred, the time T12, and the acquired sheet length. Then, the control unit 80 may transport the sheet S from that position so that the trailing end Sb of the sheet S moves to a position downstream of the transfer nip.

[0084] In the present embodiment, the printer 100 is a monochrome laser beam printer, but is not limited to this. For example, the printer 100 may be a full-color laser beam printer, in which case the intermediate transfer belt functions as an image carrier that carries a toner image.

[0085] In the present embodiment, the rotating member 91 is configured to come into contact with the fixing film 17 at the contact position, but is not limited thereto. For example, the rotating member 91 may be configured to come into contact with the pressure roller 14 instead of the fixing film 17. This can reduce the sheet S from entering the gap between the guide member facing the conveying guide 90 and the pressure roller 14. In other words, the rotating member 91 only needs to be configured to come into contact with either the fixing film 17 as the first rotating body and film, or the pressure roller 14 as the second rotating body.

[0086] In the present embodiment, the position of the sheet is detected by the discharge sensor 23 via the first flag 21 and the second flag 22, but this is not limiting. For example, an optical sensor that detects the position of the sheet by detecting light reflected from the conveyed sheet may be used instead of the discharge sensor 23.

[0087] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0088] The disclosure of the present embodiment also includes the following configuration examples and method examples. (Configuration 1) a conveying unit that conveys the sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a detection unit disposed between the fixing nip and the discharge unit in the conveying direction and configured to detect a sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet; When it is determined that a jam has occurred downstream of the fixing nip in the transport direction based on a detection result of the detection unit, the control unit executes a transport process for transporting the jammed sheet so that a rear end of the jammed sheet moves downstream of the transfer nip in the transport direction. 1. An image forming apparatus comprising: (Configuration 2) the control unit stops conveyance of the jammed sheet in the conveying process when the trailing end of the jammed sheet is positioned between the transfer nip and the fixing nip in the conveying direction. 2. The image forming apparatus according to claim 1, (Configuration 3) The detection unit is a first detection unit, a second detection unit disposed upstream of the transfer nip in the conveying direction and configured to detect the sheet; 3. The image forming apparatus according to claim 1, wherein the first and second components are arranged in a same plane. (Configuration 4) When the trailing end of the jammed sheet is located upstream of the second detection unit in the transport direction at the time when the jam occurs, the control unit transports the jammed sheet a predetermined transport distance after the second detection unit detects the trailing end. 4. The image forming apparatus according to claim 3, (Configuration 5) the control unit, in the conveying process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the conveying direction at the time when the jam occurs, calculates a conveying distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the conveying direction based on a detection result of the second detection unit. 5. The image forming apparatus according to claim 3 or 4. (Configuration 6) When the second detection unit detects the jammed sheet for a predetermined time or longer during the conveying process, the control unit stops conveying the jammed sheet. 6. The image forming apparatus according to any one of configurations 3 to 5. (Configuration 7) When it is determined that a jam of a subsequent sheet following the jammed sheet has occurred during the conveying process, the control unit stops conveying the jammed sheet. 7. The image forming apparatus according to any one of configurations 1 to 6. (Configuration 8) a leading end of the jammed sheet after the conveying process is exposed from a discharge port provided downstream of the discharge section in the conveying direction; 8. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction and a second direction. (Configuration 9) the fixing unit includes a first rotating body and a second rotating body that are each configured to be rotatable and that come into contact with each other to form the fixing nip; a conveying guide having a guide surface that guides the sheet downstream of the fixing nip in the conveying direction; a pressed member that is movably supported by the conveying guide and that is pressed by the jammed sheet to move from a first position away from the first rotating body to a second position closer to the first rotating body than the first position, 9. The image forming apparatus according to any one of configurations 1 to 8. (Configuration 10) The pressed member abuts against the first rotating body at the second position. 10. The image forming apparatus according to claim 9, (Configuration 11) The fixing unit has a heater, The first rotating body is a film heated by the heater. 11. The image forming apparatus according to configuration 9 or 10. (Configuration 12) a conveying path through which the sheet can pass, the conveying path being provided downstream of the fixing nip in the conveying direction; The detection unit is a first moving member having a first protruding portion, the first protruding portion being movable between a first protruding position where the first protruding portion protrudes toward the transport path and a first retracted position retracted from the first protruding position, the first moving member being configured to be moved from the first protruding position toward the first retracted position by the first protruding portion coming into contact with a sheet; a second moving member having a second protruding portion and movable relative to the first moving member, the second moving member being movable between a second protruding position where the second protruding portion protrudes toward the transport path and a second retracted position retracted from the second protruding position, the second moving member being configured to be moved from the second retracted position to the second protruding position by the first moving member moving from the first protruding position to the first retracted position; A sensor that detects the movement of the second moving member, When the second protruding portion is pushed by the jam sheet, the second moving member is movable from the second protruding position toward the second retracted position in a state in which the first moving member is in the first retracted position. 12. The image forming apparatus according to any one of configurations 1 to 11. (Configuration 13) The first moving member is rotatable about a rotation axis; The second moving member is rotatable around the rotation axis, When viewed along the rotation axis, a rotation direction of the first moving member when moving from the first protruding position to the first retracted position and a rotation direction of the second moving member when moving from the second protruding position to the second retracted position are opposite to each other. 13. The image forming apparatus according to claim 12, (Configuration 14) In the conveying direction, the second protrusion is disposed upstream of the first protrusion. 14. The image forming apparatus according to claim 12 or 13. (Configuration 15) Further comprising a biasing member that biases the first moving member and the second moving member, The first moving member has a support portion, The second moving member has a supported portion, The biasing member biases the first moving member and the second moving member so that the supported portion is pressed against the supporting portion. 15. The image forming apparatus according to any one of configurations 12 to 14. (Configuration 16) a developing unit including a container for containing toner, a developing member for developing the toner image by using the toner contained in the container, and a supply port for supplying toner from the toner container to the container, When the toner container is attached to the supply port, at least a portion of the toner container is exposed to the outside of the image forming apparatus. 16. The image forming apparatus according to any one of configurations 1 to 15. [Explanation of symbols]

[0089] 5: image carrier (photosensitive drum) / 6: transfer section (transfer roller) / 9: developing member (developing roller) / 14: second rotating body (pressure roller) / 17: first rotating body, film (fixing film) / 18: heater / 21: first moving member (first flag) / 21a: first protruding portion / 21b: supporting portion (rotation stopper portion) / 22: second moving member (second flag) / 22a: second protruding portion / 22b: supported portion (regulated portion) / 23: sensor (ejection sensor) / 24: urging member (flag urging spring) / 42: transport path / 61: developing unit (process cartridge ) / 70: discharge section / 80: control section / 85: second detection section (registration sensor) / 90: transport guide / 90a: guide surface / 91: pressed member (rotating member) / 95: discharge port / 96: detection section, first detection section (sheet detection unit) / 99: transport unit / 100: image forming device (printer) / 170a: storage section / 190: supply port / 200: fixing section (fixing device) / 200F: fixing nip / CD: transport direction / d: transport distance / RF: rotation axis / S: sheet, jammed sheet / Sa: leading edge / Sb: trailing edge / T1: transfer nip

Claims

1. a conveying unit that conveys the sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section including a first rotating body and a second rotating body that are each configured to be rotatable and that form a fixing nip by contacting each other, and that fixes the toner image transferred to a sheet at the transfer nip onto the sheet at the fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a detection unit disposed between the fixing nip and the discharge unit in the conveying direction and configured to detect a sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet, and when it is determined that a jam has occurred based on a detection result from the detection unit, executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the detection unit moves downstream of the transfer nip in the transport direction; a conveying guide having a guide surface that guides the sheet downstream of the fixing nip in the conveying direction; a pressed member that is movably supported by the conveying guide and that is pressed by the jammed sheet to move from a first position away from the first rotating body to a second position closer to the first rotating body than the first position, The pressed member abuts against the first rotating body at the second position.

1. An image forming apparatus comprising:

2. the control unit stops conveyance of the jammed sheet in the conveying process when the trailing end of the jammed sheet is positioned between the transfer nip and the fixing nip in the conveying direction.

2. The image forming apparatus according to claim 1,

3. The detection unit is a first detection unit, a second detection unit that is disposed upstream of the transfer nip in the conveying direction and detects the sheet; 2. The image forming apparatus according to claim 1,

4. When the trailing end of the jammed sheet is located upstream of the second detection unit in the transport direction at the time when the jam occurs, the control unit transports the jammed sheet a predetermined transport distance after the second detection unit detects the trailing end.

4. The image forming apparatus according to claim 3.

5. the control unit, in the conveying process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the conveying direction at the time when the jam occurs, calculates a conveying distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the conveying direction based on a detection result of the second detection unit.

4. The image forming apparatus according to claim 3.

6. When the second detection unit detects the jammed sheet for a predetermined time or longer during the conveying process, the control unit stops conveying the jammed sheet.

4. The image forming apparatus according to claim 3.

7. When it is determined that a jam of a subsequent sheet following the jammed sheet has occurred during the conveying process, the control unit stops conveying the jammed sheet.

2. The image forming apparatus according to claim 1,

8. a leading end of the jammed sheet after the conveying process is exposed from a discharge port provided downstream of the discharge section in the conveying direction; 2. The image forming apparatus according to claim 1,

9. The fixing unit has a heater, The first rotating body is a film heated by the heater.

2. The image forming apparatus according to claim 1,

10. a conveying path through which the sheet can pass, the conveying path being provided downstream of the fixing nip in the conveying direction; The detection unit is a first moving member having a first protruding portion, the first protruding portion being movable between a first protruding position where the first protruding portion protrudes toward the transport path and a first retracted position retracted from the first protruding position, the first moving member being configured to be moved from the first protruding position toward the first retracted position by the first protruding portion coming into contact with a sheet; a second moving member having a second protruding portion and movable relative to the first moving member, the second protruding portion being movable between a second protruding position where the second protruding portion protrudes toward the transport path and a second retracted position retracted from the second protruding position, the second moving member being configured to be moved from the second retracted position to the second protruding position by the first moving member moving from the first protruding position to the first retracted position; a sensor for detecting the movement of the second moving member, When the second protruding portion is pushed by the jammed sheet, the second moving member is movable from the second protruding position toward the second retracted position in a state in which the first moving member is in the first retracted position.

2. The image forming apparatus according to claim 1,

11. The first moving member is rotatable about a rotation axis; The second moving member is rotatable around the rotation axis, When viewed along the rotation axis, a rotation direction of the first moving member when moving from the first protruding position to the first retracted position and a rotation direction of the second moving member when moving from the second protruding position to the second retracted position are opposite to each other.

11. The image forming apparatus according to claim 10.

12. The second protrusion is disposed upstream of the first protrusion in the conveying direction.

11. The image forming apparatus according to claim 10.

13. a biasing member that biases the first moving member and the second moving member, The first moving member has a support portion, The second moving member has a supported portion, The biasing member biases the first moving member and the second moving member so that the supported portion is pressed against the supporting portion.

11. The image forming apparatus according to claim 10.

14. A conveying unit that conveys a sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a detection unit disposed between the fixing nip and the discharge unit in the conveying direction and configured to detect a sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet; a conveying path through which a sheet can pass, the conveying path being provided downstream of the fixing nip in the conveying direction; when it is determined that a jam has occurred based on a detection result of the detection unit, the control unit executes a conveying process to convey the jammed sheet such that a trailing end of the jammed sheet detected by the detection unit moves downstream of the transfer nip in the conveying direction; The detection unit is a first moving member having a first protruding portion, the first protruding portion being movable between a first protruding position where the first protruding portion protrudes toward the transport path and a first retracted position retracted from the first protruding position, the first moving member being configured to be moved from the first protruding position toward the first retracted position by the first protruding portion coming into contact with a sheet; a second moving member having a second protruding portion and movable relative to the first moving member, the second protruding portion being movable between a second protruding position where the second protruding portion protrudes toward the transport path and a second retracted position retracted from the second protruding position, the second moving member being configured to be moved from the second retracted position to the second protruding position by the first moving member moving from the first protruding position to the first retracted position; a sensor for detecting the movement of the second moving member, When the second protruding portion is pushed by the jammed sheet, the second moving member is movable from the second protruding position toward the second retracted position in a state in which the first moving member is in the first retracted position.

1. An image forming apparatus comprising:

15. The first movable member is rotatable about a rotation axis, The second moving member is rotatable around the rotation axis, When viewed along the rotation axis, a rotation direction of the first moving member when moving from the first protruding position to the first retracted position and a rotation direction of the second moving member when moving from the second protruding position to the second retracted position are opposite to each other.

15. The image forming apparatus according to claim 14.

16. In the conveying direction, the second protrusion is disposed upstream of the first protrusion.

15. The image forming apparatus according to claim 14.

17. The control unit stops the conveyance of the jammed sheet in the conveying process when the rear end of the jammed sheet is located between the transfer nip and the fixing nip in the conveying direction.

15. The image forming apparatus according to claim 14.

18. The detection unit is a first detection unit, a second detection unit that is disposed upstream of the transfer nip in the conveying direction and detects the sheet; 15. The image forming apparatus according to claim 14.

19. In the conveying process, if the rear end of the jammed sheet is located upstream of the second detection unit in the conveying direction at the time when the jam occurs, the control unit conveys the jammed sheet a predetermined conveying distance after the second detection unit detects the rear end.

20. The image forming apparatus according to claim 18,

20. In the conveying process, when the rear end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the conveying direction at the time the jam occurs, the control unit calculates the conveying distance of the jammed sheet until the rear end moves downstream of the transfer nip in the conveying direction based on the detection result of the second detection unit.

20. The image forming apparatus according to claim 18,

21. The control unit stops conveying the jammed sheet when the second detection unit detects the jammed sheet for a predetermined time or more during the conveying process.

20. The image forming apparatus according to claim 18,

22. The control unit stops conveying the jammed sheet when it is determined that a jam of a subsequent sheet following the jammed sheet has occurred during the conveying process.

15. The image forming apparatus according to claim 14.

23. A leading end of the jammed sheet after the conveying process is exposed from a discharge port provided downstream of the discharge section in the conveying direction.

15. The image forming apparatus according to claim 14.

24. The fixing section has a first rotating body and a second rotating body that are each rotatable and abut against each other to form the fixing nip, a conveying guide having a guide surface that guides the sheet downstream of the fixing nip in the conveying direction; a pressed member that is movably supported by the conveying guide and that is pressed against the jammed sheet to move from a first position away from the first rotating body to a second position closer to the first rotating body than the first position, 15. The image forming apparatus according to claim 14.

25. The fixing unit has a heater, The first rotating body is a film heated by the heater.

25. The image forming apparatus according to claim 24.

26. A conveying unit that conveys a sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection unit that is disposed between the fixing nip and the discharge unit in the conveying direction and detects a sheet; a second detection unit disposed upstream of the transfer nip in the conveying direction and configured to detect the sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet, and when it is determined that a jam has occurred based on a detection result of the first detection unit, a control unit that executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, When the trailing end of the jammed sheet is located upstream of the second detection unit in the transport direction at the time when the jam occurs, the control unit transports the jammed sheet a predetermined transport distance after the second detection unit detects the trailing end.

1. An image forming apparatus comprising:

27. ​​A conveying unit that conveys a sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection unit that is disposed between the fixing nip and the discharge unit in the conveying direction and detects a sheet; a second detection unit disposed upstream of the transfer nip in the conveying direction and configured to detect the sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet, and when it is determined that a jam has occurred based on a detection result of the first detection unit, a control unit that executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, the control unit, in the conveying process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the conveying direction at the time when the jam occurs, calculates a conveying distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the conveying direction based on a detection result of the second detection unit.

1. An image forming apparatus comprising:

28. A conveying unit that conveys a sheet in a conveying direction; an image carrier that carries a toner image; a transfer section that forms a transfer nip together with the image carrier and transfers the toner image on the image carrier to a sheet transported by the transport unit at the transfer nip; a fixing section that fixes the toner image transferred to the sheet at the transfer nip onto the sheet at a fixing nip; a discharge section that discharges the sheet on which the toner image has been fixed by the fixing section; a first detection unit that is disposed between the fixing nip and the discharge unit in the conveying direction and detects a sheet; a second detection unit disposed upstream of the transfer nip in the conveying direction and configured to detect the sheet; a control unit that controls the transport unit and the image carrier to control transport of a sheet, and when it is determined that a jam has occurred based on a detection result of the first detection unit, a control unit that executes a transport process to transport the jammed sheet so that the trailing end of the jammed sheet detected by the first detection unit moves downstream of the transfer nip in the transport direction, the control unit, in the conveying process, when the trailing end of the jammed sheet is located downstream of the second detection unit and upstream of the transfer nip in the conveying direction at the time when the jam occurs, calculates a conveying distance of the jammed sheet until the trailing end moves downstream of the transfer nip in the conveying direction based on a detection result of the second detection unit.

1. An image forming apparatus comprising:

29. a developing unit including a container for containing toner, a developing member for developing the toner image by using the toner contained in the container, and a supply port for supplying toner from the toner container to the container, When the toner container is attached to the supply port, at least a portion of the toner container is exposed to the outside of the image forming apparatus.

29. The image forming apparatus according to claim 1,

30. Further comprising a motor for driving the transport unit, The fixing unit is driven by the motor.

29. The image forming apparatus according to claim 1,

Images