JP2016071124A - Sheet conveying device and image forming apparatus - Google Patents

Abstract

PURPOSE: To reduce a time required for a user to perform jam processing to resolve paper jam that has occurred in a sheet conveying device.CONSTITUTION: A sheet conveying device includes: first conveying means that can hold and convey a sheet; second conveying means that is provided on the upstream side in the sheet conveyance direction with respect to the first conveying means and can hold and convey the sheet held and conveyed by the first conveying means; detection means that detects abnormality in conveyance of a sheet; and control means that, when the detection means has detected abnormality in conveyance of a sheet, controls the first conveying means and the second conveying means in a direction to form sagging on the sheet.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet by a conveying roller, and particularly relates to a jam processing.

  2. Description of the Related Art In recent years, image forming apparatuses such as copying machines, printers, and facsimile machines, and image reading apparatuses such as scanners, are supplied and conveyed sheets as sheet materials by sheet conveying apparatuses. In these sheet conveying apparatuses, a sheet is generally configured to be nipped and conveyed by a conveying roller pair composed of two rollers pressed against each other. Many of the conveyance roller pairs related to such an apparatus are constituted by a conveyance roller to which driving is transmitted from a drive motor, and a driven roller that is pressed and driven by the conveyance roller.

  In the sheet conveying apparatus having the above configuration, when a conveyance failure, that is, a jam occurs in the apparatus main body, the user needs to remove the jammed sheet or the sheet staying in the machine. However, when the sheet is held between the pair of conveyance rollers, it is not easy to rotate the conveyance roller because it is connected to the drive motor. Therefore, the user has to pull the in-machine sheet with force, and the workability at the time of jam processing is poor.

  With respect to such a problem, in Patent Document 1, when conveyance is stopped in a state where the sheet is sandwiched between the conveyance roller pair, the conveyance roller pair is set as the conveyance direction until the sheet is released from the nipping of the conveyance roller pair. There has been proposed a sheet conveying apparatus that is configured to be driven in the reverse direction so that a user can easily perform jam processing.

JP 2001-270634 A

  However, as in Patent Document 1, when an attempt is made to rotate the conveyance roller pair in the direction opposite to the conveyance direction until the sheet is removed from the nipping of the conveyance roller pair, the sheet is fed in order to be removed from the nipping of the conveyance roller pair. The sheet had to be conveyed in the reverse direction to the cassette. As a result, when a jam occurs on the downstream side in the sheet conveyance direction, it may take time for the user to perform the jam processing.

  In view of the above, an object of the sheet conveying apparatus of the present invention is to shorten the time until a user performs jam processing when a jam occurs.

  A first conveyance unit capable of nipping and conveying a sheet; and a second conveyance unit provided upstream of the first conveyance unit in a sheet conveyance direction and capable of nipping and conveying the sheet nipped and conveyed by the first conveyance unit A conveying unit; a detecting unit that detects a sheet conveyance abnormality; and a sheet conveying abnormality detected by the detection unit, the first conveying unit and the second conveying unit in a direction in which slack is formed in the sheet. Control means for controlling the means.

  The sheet conveying apparatus of the present invention can shorten the time until the user performs jam processing when a jam occurs.

Schematic sectional view showing the configuration of the image forming apparatus Sectional view showing the positional relationship of the sheet when a delayed jam occurs Sectional view showing sagging formation operation when delayed jam occurs Sectional view showing the positional relationship of sheets when stagnant jam occurs Sectional view showing sagging formation when stagnant jam occurs Block diagram showing control configuration A flowchart showing the operation of the CPU 600 when a jam occurs. The flowchart which shows operation | movement of CPU600 at the time of performing jam state determination processing

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the present embodiment, an image reading apparatus used in an image forming apparatus such as a copying machine is taken as an example of the image reading apparatus, but the present invention is not limited to this. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the present invention. .

<First Embodiment>
Hereinafter, the image forming apparatus according to the present embodiment will be described with reference to the drawings.
FIG. 1 is a schematic sectional view of an image forming apparatus of the present invention.
In the image forming apparatus A, a sheet feeding unit 10, an image forming unit 20, a fixing unit 30, and a sheet discharge unit 40 are provided in order from the upstream side in the sheet conveying direction. Further, a sheet refeeding unit 50 is provided.

In the sheet feeding unit 10, the sheets S stacked on the feeding cassette 11 and the manual feed tray 16 are fed to the image forming unit 20.
The sheet S stored in the feeding cassette 11 is fed to the separation roller pair 13 as the pickup roller 12 rotates. When the sheet S is being double fed, the sheet S is separated into one sheet by a separation roller pair 13 composed of a normal rotation roller and a reverse rotation roller, and the sheet is supplied to the conveyance path.

  Then, the sheet S is conveyed to the registration roller pair 15 by the conveyance roller pair 14. Here, the skew of the sheet S is corrected by the leading edge of the sheet S following the nip of the registration roller pair 15 whose rotation is stopped.

  When the sheet S is fed from the manual feed tray 16, first, the manual feed tray 16 is opened and the sheet S is placed thereon, and the uppermost sheet S is drawn into the image forming apparatus A by the supply roller 17. Then, the sheet S is supplied to the conveyance roller pair 14 by the conveyance roller pair 18 and conveyed to the registration roller pair 15, whereby the skew of the sheet S is corrected.

The sheet whose skew has been corrected is conveyed to the image forming unit 20 by the registration roller pair 15 rotating at a predetermined timing.
In the image forming unit 20, the surface of a photosensitive drum 21 as an image carrier is uniformly charged by a charging roller 22. The uniformly charged photosensitive drum 21 is irradiated with laser light corresponding to image information from the laser unit 23. In the portion of the photosensitive drum 21 irradiated with the laser light, the charge charged by the charging roller 22 is removed, and an electrostatic latent image corresponding to the image information is formed. The electrostatic latent image formed here is visualized as a developer image with a developer attached by a developing roller 24 as a developing means.

  The developer image is conveyed to a transfer nip between the photosensitive drum 21 and a transfer roller 25 as a transfer unit by the rotation of the photosensitive drum 21. The sheet S is conveyed from the registration roller pair 15 to the transfer nip in accordance with the timing at which the developer image is conveyed to the transfer nip. The conveyed sheet S is nipped and conveyed by the transfer roller 25 that contacts the photosensitive drum 21 at the transfer nip, and the developer image formed on the photosensitive drum 21 is transferred by the transfer roller 25. The toner remaining on the surface of the photosensitive drum 21 after the developer image is transferred to the sheet S is removed by the cleaning member 26.

Next, the sheet S on which the developer image is formed is conveyed to the fixing unit 30.
In the fixing unit 30, a fixing nip is formed by a fixing film 31 heated to a predetermined fixing temperature by a heat source such as a ceramic heater and a pressure roller 32 in contact with the fixing film 31. The sheet S on which the developer image is formed is fed into the fixing nip, and is nipped and conveyed by a fixing film 31 as a fixing unit and a pressure roller 32, and is heated and pressed. To be established. Then, the sheet S on which the developer image is fixed by the fixing film 31 and the pressure roller 32 has the leading or trailing end of the sheet S removed from the fixing unit 30 by the fixing paper discharge sensor 33 as the first detection unit. It is detected.
The fixing unit 30 is a fixing unit such as an aluminum roller that is heated to a predetermined fixing temperature by a heat source such as a halogen lamp instead of the on-demand fixing method in which the sheet S is heated and pressed by the fixing film 31 and the pressure roller 32. You may use the heating roller system heated with a roller.
Next, when an image is formed only on one side, the sheet S on which the developer image is fixed is conveyed to the sheet discharge unit 40 and discharged to the discharge tray 42 by a discharge roller pair 41 as discharge means.
At this time, the sheet S is guided to the discharge roller pair 41 by switching the switching unit 43 provided on the downstream side of the fixing unit 30 in the sheet conveyance direction to the discharge roller pair 41 side.

  Here, since there is a limit on the stacking height of the sheets that can be stacked on the discharge tray 42, the full load detection sensor 44 serving as a second detection unit that detects that the predetermined stacking amount has been reached is provided by the discharge roller pair 41. It is provided on the downstream side in the sheet conveying direction. When the full load detection sensor 44 detects the full load of sheets on the discharge tray 42, the operation of the image forming apparatus A is stopped. The full load detection sensor 44 is also used as a function in this embodiment to detect that the leading edge of the sheet has been conveyed by the discharge roller pair 41.

When images are formed on both sides of the sheet S, the switching unit 43 is switched, and the sheet S on which the image is formed on the first side is guided to the sheet refeeding unit 50. Specifically, the sheet S is guided to the reverse roller pair 52 by the guide unit 51. After the sheet S is conveyed by a predetermined distance, the reverse roller pair 52 temporarily stops the conveyance before the trailing end of the sheet S exits the reverse roller pair, and then rotates in the reverse direction with respect to the sheet conveyance. The sheet S reversed by the reversing roller pair 52 is conveyed to the sheet re-feeding unit 50 when the guide unit 51 is switched.
The sheet S conveyed to the sheet re-feeding unit 50 is conveyed along a re-feed path by re-feed roller pairs 53 a and 53 b and is conveyed to the registration roller pair 16. After the skew is corrected by the registration roller pair 16, the developer image is formed on the second surface of the sheet S by being conveyed to the transfer nip. Thereafter, the developer image is fixed on the sheet S by being conveyed through the fixing nip portion N2 in the same manner as when the image is formed on the surface, and the sheet S on which the image is formed on both sides is discharged by the discharge roller pair 41 to the discharge tray 42. Is discharged.

  In the above description, the sheet S is reversed using the reversing roller pair 52. However, the sheet S may be reversed using the discharge roller pair 41. At this time, when images are formed on both surfaces of the sheet S, after the sheet S is conveyed by the discharge roller pair 41 for a predetermined distance, the conveyance is temporarily stopped before the rear end of the sheet S passes through the discharge roller pair 41. Thereafter, the sheet S is reversed by rotating the discharge roller pair 41 in the opposite direction to that during sheet conveyance. Then, by providing a member that switches the conveyance destination of the sheet S to the re-feeding path, the reversed sheet S is conveyed to the sheet re-feeding unit 50.

  Although the image forming operation by the image forming apparatus A has been described above, an image reading apparatus that reads an original image is further provided, and an image is formed on a sheet by the image forming apparatus A based on the original image read by the image reading apparatus. The structure to form may be sufficient.

  At this time, when copying the original, the image data read by the image reading apparatus is sent to the image forming apparatus A, so that the laser light corresponding to the image data is irradiated from the laser unit 23 to the photosensitive drum 21, and the image is read. An image corresponding to the data is formed on the sheet.

Here, when a conveyance failure, that is, a jam occurs in the conveyance path of the image forming apparatus A, the user needs to remove the sheet or the sheet remaining in the machine.
In the present embodiment, as an example of detecting the jam state from the fixing unit 30 to the discharge unit 40, a description will be given using the fixing discharge sensor 33 and the full load detection sensor 44.

  Specifically, after the leading edge of the sheet is detected by the fixing paper discharge sensor 33, the case where the leading edge of the sheet is not detected even after a predetermined time has passed is detected as a delay jam. Further, after the leading end of the sheet is detected by the fixing discharge sensor 33 and the full load detection sensor 44 detects the leading end, the case where the fixing discharge sensor 33 does not detect the trailing end of the sheet is retained even after a predetermined time has elapsed. Detect with jam. Here, the delay jam occurs when the conveyance of the sheet is delayed due to insufficient conveyance force of the roller, or when the conveyance of the sheet is delayed due to the leading edge of the sheet clogged in the conveyance path. Further, the stay jam occurs when the leading edge of the sheet is detected at a predetermined time, but the trailing edge of the sheet cannot be normally conveyed in the fixing unit 30. In any case, when a jam is detected in the transport path, the operation of the entire image forming apparatus A is stopped.

  At this time, when the stay jam occurs, the leading edge of the sheet is on the downstream side in the sheet conveyance direction as compared with the case where the delay jam occurs. A predetermined time from when the leading edge of the sheet is detected by the fixing paper discharge sensor 33 to when the trailing edge of the sheet is detected by the fixing paper discharge sensor 33 is from when the leading edge of the sheet is detected by the fixing paper discharge sensor 33. It is longer than a predetermined time until the leading edge of the sheet is detected by the full load detection sensor 44. This is to detect whether or not a stay jam has occurred after detecting whether or not a delay jam has occurred.

Next, the operation of the conveying means when a jam occurs in this embodiment will be described. First, the operation of the transport unit when a delay jam occurs will be described.
FIG. 2 is a cross-sectional view showing the positional relationship of sheets when a delay jam occurs in the conveyance path.
The delay jam may occur when the conveyance of the sheet is delayed due to insufficient conveyance force of the roller, or when the conveyance of the sheet is delayed due to the leading edge of the sheet clogged in the conveyance path.

  In FIG. 2, after the leading edge of the sheet S1 is detected by the fixing sheet discharge sensor 33, the full load detection sensor 44 does not detect the leading edge of the sheet even after a predetermined time has elapsed, so that it is determined as a delay jam, and the sheet S1 in the transport path. In addition, the conveyance of the sheet S2 is stopped.

At this time, the conveyance of the sheet S <b> 1 is stopped while being sandwiched between the fixing film 31, the pressure roller 32, and the discharge roller pair 41 as in the case of the jamming. Further, it is expected that the conveyance of the sheet S2 is stopped while being sandwiched between the conveyance roller pair 14 and the registration roller pair 15 as in the case of the jamming. When a jam occurs in the transport path, the image forming apparatus A does not resume the operation until the sheets S1 and S2 in the transport path are removed.
Here, a part of the sheet re-feeding unit 50 is configured integrally with a door unit (not shown) that opens a part of the image forming apparatus A. Therefore, the user opens a part of the sheet re-feeding unit 50 by opening the door, and removes the sheet in the conveyance path.

  Here, in FIG. 2, a portion surrounded by an alternate long and short dash line is a part of the sheet re-feeding unit 50 integrated with the door. The user performs the removal operation of the sheet S1 and the sheet S2 in the apparatus in a state where a part of the sheet refeeding unit 50 integrated with the door is opened.

However, since the sheet S1 is sandwiched between the discharge roller pair 41, the fixing film 31 and the pressure roller 32, and the sheet S2 is sandwiched between the registration roller pair 15 and the conveyance roller pair 14, it is difficult for the user to remove. .
Therefore, in this embodiment, in order to make it easier for the user to take out the sheet S1 and the sheet S2, slack is formed in the sheet S1 and the sheet S2.

FIG. 3 is a cross-sectional view showing a sheet sagging formation operation when a delay jam occurs.
Here, the sheet sag forming operation is performed before the door of the image forming apparatus A is opened by the user.
When a delay jam occurs in the conveyance path and the operation of the image forming apparatus A is stopped, first, the pressure roller 32 and the conveyance roller pair 14 are rotated, and the upstream ends of the sheets S1 and S2 are conveyed at the sheet conveyance. To the same direction. At this time, since the fixing film 31 is pressed against the pressure roller 32, the fixing film 31 rotates following the pressure roller 32. Further, the discharge roller pair 41 and the registration roller pair 15 maintain a state in which the conveyance of the sheet S1 and the sheet S2 is stopped.

  Here, the pressure roller 32 and the conveyance roller pair 14 on the upstream side in the conveyance direction are rotated in the same direction as the sheet conveyance direction because the leading edge of the sheet reaches the full load detection sensor 44 within a predetermined time when a delay jam occurs. This is because the trailing edge of the sheet is on the upstream side in the conveyance direction as compared with the case where the jamming occurs. Therefore, when the discharge roller pair 41 and the registration roller pair 15 on the downstream side in the transport direction are rotated in the reverse direction, the leading edge of the sheet may pass through the roller nip as compared with the case where the discharge roller pair 41 and the registration roller pair 15 are rotated in the forward direction. Therefore, in order to form a slack with respect to the sheet in the conveyance path, the pressure roller 32 and the conveyance roller pair 14 on the upstream side in the conveyance direction may be rotated in the forward direction.

  The fixing film 31, the pressure roller 32, and the conveying roller pair 14 stop operating after conveying a sheet for a predetermined distance, and stop conveying the sheet S1 and the sheet S2.

In FIG. 3, the sheets S <b> 1 and S <b> 2 each indicate a state when a delayed jam occurs and a solid line indicates a state when sagging is formed.
Thus, by forming the slack in the sheet S1 and the sheet S2, the user can easily take out the sheet S1 and the sheet S2.

Next, the operation of the transport unit when a stay jam occurs will be described.
FIG. 4 is a cross-sectional view showing the positional relationship of sheets when a stay jam occurs in the conveyance path.
The stay jam can occur when the trailing edge of the sheet cannot be normally conveyed in the fixing unit 30.
In FIG. 4, after the leading edge of the sheet S1 is detected by the fixing paper discharge sensor 33, the fixed paper discharge sensor 33 does not detect the trailing edge of the sheet S1 even after a predetermined time has elapsed, so that it is determined as a stay jam, and the inside of the conveyance path. The conveyance of the sheet S1 and the sheet S2 is stopped.

  At this time, the sheet S1 is conveyed while being sandwiched between the discharge roller pair 41 as the first conveying means on the downstream side and the fixing film 31 and the pressure roller 32 as the second conveying means on the upstream side. Has been stopped. Further, since the sheet S2 is a subsequent sheet that is sequentially conveyed, the sheet S2 is sandwiched between the registration roller pair 15 as the first conveying means on the downstream side and the conveying roller pair 14 as the second conveying means on the upstream side. It is expected that the transport is stopped in the state. When a jam occurs in the transport path, the image forming apparatus A does not resume operation until the sheets S1 and S2 in the transport path are removed.

  Here, as in the case of the occurrence of the delayed jam described above, the user opens a part of the sheet re-feeding unit 50 that is integrally formed with the door surrounded by the chain line, thereby allowing the sheet in the conveyance path to be opened. Remove.

FIG. 5 is a cross-sectional view showing a sheet slack forming operation when a stay jam occurs.
Here, the sheet sag forming operation is performed before the door of the image forming apparatus A is opened by the user.
When a jam occurs in the conveyance path and the operation of the image forming apparatus A is stopped, first, the discharge roller pair 41 and the registration roller pair 15 are rotated in the reverse direction, and the downstream ends of the sheets S1 and S2 are conveyed to the sheet. Transport in the opposite direction. At this time, the fixing film 31, the pressure roller 32, and the conveyance roller pair 14 are kept in a state where conveyance is stopped. Here, the discharge roller pair 41 and the registration roller pair 15 on the downstream side in the transport direction are rotated in reverse because the trailing edge of the sheet does not reach the fixing discharge sensor 33 within a predetermined time when a jam occurs. This is because the leading edge of the sheet is conveyed to the downstream side as compared to when a jam occurs. Therefore, when the pressure roller 32 and the conveyance roller pair 14 on the upstream side in the conveyance direction are rotated in the forward direction, the trailing edge of the sheet may pass through the nip of the roller as compared with the case where the pressure roller 32 and the conveyance roller pair 14 are rotated in the reverse direction. Therefore, in order to form a slack with respect to the sheet in the conveyance path, the discharge roller pair 41 and the registration roller pair 15 on the downstream side in the conveyance direction may be rotated in reverse.

  The pair of discharge rollers 41 and the pair of registration rollers 15 stop the reverse rotation operation after transporting the sheet for a predetermined distance, and stop transporting the sheets S1 and S2 in the opposite direction to the sheet transport.

In FIG. 5, for the sheets S <b> 1 and S <b> 2, the broken line indicates the state when the stay jam occurs, and the solid line indicates the state when the slack is formed.
Thus, by forming the slack in the sheet S1 and the sheet S2, the user can easily take out the sheet S1 and the sheet S2.

  As described above, the roller to be rotated and the rotation direction are changed depending on the type of jam depending on the type of jam, when the stay jam occurs and when the delay jam occurs. This is because the position of the sheet to be different is different. For example, when a stay jam occurs, the downstream end of the sheet in the conveyance direction is on the downstream side compared to when a delayed jam occurs. Therefore, when a stay jam occurs, the discharge roller pair 41 and the registration roller pair 15 on the downstream side are rotated in reverse to form a slack in the sheet.

When a delayed jam occurs, the downstream end in the sheet conveyance direction is on the upstream side compared to when a stagnant jam occurs. Therefore, when a delay jam occurs, the pressure roller 32 and the conveyance roller pair 14 on the upstream side are rotated forward to form a sag in the sheet.
At this time, the discharge roller pair 41 and the registration roller pair 15 convey a sheet of about 10 mm, so that when a user removes the sheet, a finger or a hand easily enters the slack of the sheet, and the sheet is easily grasped.

In the above embodiment, the operation for forming the slack in the sheet has been described. However, the nipping of the sheet by one roller pair may be released without forming the slack. By doing in this way, it becomes easy for the user to grasp the sheet end portion with respect to the sheet that is nipped between the roller pair and stopped from being conveyed, and jammed easily. Here, when the inside of the conveyance path is narrow and the user does not easily grasp the sheet end, it is more effective to form a slack on the sheet.
The sheet conveyance distance when the slack is formed on the sheet may not be limited to 10 mm as long as the sheet does not pass through the nip portion of the discharge roller pair 41 and the nip portion of the registration roller pair 15.
As described above, when a jam occurs in the apparatus, it is possible to improve the workability of the user during the jam processing by forming a slack in the sheet remaining in the apparatus.

Next, the control configuration of the image forming apparatus in this embodiment will be described.
FIG. 6 is a block diagram illustrating a control configuration of the image forming apparatus according to the present exemplary embodiment.

  The CPU 600 controls the entire image forming apparatus A. The CPU 600 detects a sheet conveyance abnormality, a determination unit that determines a jam state in the conveyance path, and a slack with respect to the sheet in the conveyance path. It also functions as a control means for forming. A RAM 601 is a work area for the CPU 600 and a temporary storage area for data. A ROM 602 stores a firmware program for controlling the image forming apparatus A and a boot program for controlling the firmware program, and is used by the CPU 600. A communication I / F 603 is connected to an external computer or the like, and transfers image data or the like via the communication I / F 603. The operation unit 604 receives an instruction from the user or notifies the user when an error such as a jam occurs. The interlock detection unit 605 detects the open / closed state of the door portion of the image forming apparatus A.

  The main motor 606 operates to rotate the registration roller pair 15, the photosensitive drum 21, and the developing roller 24 in a predetermined rotation speed and rotation direction by a drive gear train. Further, the main motor 606 can select connection and disconnection of drive connection by a clutch mechanism 607, and rotate and stop the photosensitive drum 21, the developing roller 24, and the registration roller pair 15 at predetermined timings, respectively. Is possible.

  The paper feed motor 608 rotates and stops the pickup roller 12, the separation roller pair 13, and the conveyance roller pair 14 in a predetermined rotation speed and rotation direction.

  The fixing motor 609 rotates and stops the pressure roller 32 in a predetermined rotation speed and rotation direction. Since the fixing film 31 is in pressure contact with the pressure roller 32, the fixing film 31 is driven to rotate by the pressure roller 32.

  The paper discharge motor 610 rotates and stops the discharge roller pair 41 in a predetermined rotation speed and rotation direction.

Next, a control operation when a jam occurs in the conveyance path of the image forming apparatus A will be described.
FIG. 7 is a flowchart showing the operation of the CPU 600 in this embodiment.
7 is performed when the image forming apparatus A is performing an image forming operation. During the image forming operation, the CPU 600 performs jam state determination processing in step S701 as needed. Details of the jam state determination processing will be described later.

  In step S <b> 702, it is determined whether a jam has occurred in the conveyance path of the image forming apparatus A. At this time, if a jam does not occur (No in step S702), the image forming operation is performed as usual until a jam occurs in the transport path. If a jam has occurred (YES in step S703), the main motor 606, the paper feed motor 608, the fixing motor 609, and the paper discharge motor 610 are stopped, and the conveyance of the sheet in the image forming apparatus A is stopped.

  Then, it is determined whether or not it is determined as a jam in the jam state determination process in step S701 (Sstep 704). If the generated jam is a staying jam, the discharge motor 610 and the main motor 606 in which the drive connection between the photosensitive drum 21 and the developing roller 24 is released by the clutch mechanism 607 are reversed in step S705. The discharge roller pair 41 and the registration roller pair 15 are rotated in the reverse direction. And as shown in FIG. 5, the downstream edge part of the sheet | seat S1 and the sheet | seat S2 is conveyed in the reverse direction with respect to the time of sheet conveyance. If the downstream ends of the sheet S1 and the sheet S2 are conveyed by a predetermined distance in step S706 (Yes in step S706), the reverse rotation of the main motor 606 and the discharge motor 610 is stopped in step S707, and the discharge roller pair 41 In addition, the conveyance of the sheet by the registration roller pair 15 is stopped. When the downstream ends of the sheet S1 and the sheet S2 are not conveyed for a predetermined distance (No in step S706), the main motor 606 and the discharge motor 610 are continuously reversely rotated until they are conveyed for a predetermined distance.

  On the other hand, if it is determined that the jam that has occurred in step S704 is not a stay jam but a delay jam (No in step S704), the fixing motor 609 and the paper feed motor 608 are rotated forward in step S710. The pressure roller 32 and the conveyance roller pair 14 are rotated forward. And as shown in FIG. 3, the upstream edge part of the sheet | seat S1 and the sheet | seat S2 is conveyed in the same direction as the time of sheet conveyance. If it is determined in step S706 that the upstream ends of the sheets S1 and S2 have been conveyed by a predetermined distance (Yes in step S706), the rotation of the fixing motor 609 and the paper feed motor 608 is stopped in step S707. Then, the sheet conveyance by the pressure roller 32 and the conveyance roller pair 14 is stopped. When the upstream end portions of the sheet S1 and the sheet S2 are not conveyed for a predetermined distance (No in step S706), the fixing motor 609 and the paper feeding motor 608 are continuously rotated until the sheet S1 and the sheet S2 are conveyed for a predetermined distance.

  After stopping the conveyance of the sheet, the operation unit 604 notifies that a jam has occurred in the apparatus, and prompts the user to remove the sheet in the conveyance path (step S709).

  Next, the state of the fixing paper discharge sensor 33 is detected in step S710, and the state of the full load detection sensor 44 is detected in step S711. In step S712, it is determined whether all the fixing paper discharge sensor 33 and the full load detection sensor 44 are turned off and all the jams in the transport path have been removed. If all the jams in the transport path have not been removed (No in step S712), the state detection of the fixing paper discharge sensor 33 in step S810 and the state detection of the full load detection sensor 44 in step S711 are repeated. When all the jams in the transport path are removed (Yes in step S712), in step S713, the interlock detection unit 605 is turned on, and it is determined whether or not the door of the image forming apparatus A is closed. . When it is determined that the door portion of the image forming apparatus A is in the closed state (Yes in step S713), the operations of the main motor 606, the paper feed motor 608, the fixing motor 609, and the paper discharge motor 610 are restarted to perform the image forming operation. Is resumed (step S714). When it is determined that the door portion of the image forming apparatus A is not closed (No in step S713), the process waits until the door portion is closed.

Next, the jam state determination process in step S701 will be described.
FIG. 8 is a flowchart showing the operation of the CPU 600 in the jam state determination process in step S701.
When the jam state determination process is started, the CPU 600 detects the state of the fixing paper discharge sensor 33 in step S801.
If the fixing paper discharge sensor 33 is turned on (Yes in step S802), the count is started in step S803. If the fixing paper discharge sensor 33 is not turned on (No in step S802), the state of the fixing paper discharge sensor 33 is detected until the fixing paper discharge sensor 33 is turned on.

  In step S804, it is determined whether or not a predetermined time has elapsed since the fixing paper discharge sensor 33 was turned on. If the predetermined time has not elapsed (No in step S804), the count is continued until the predetermined time elapses.

If it is determined in step S804 that the predetermined time has elapsed (Yes in step S804), the CPU 600 detects the state of the full load detection sensor 44 (step S805).
In step S806, it is determined whether or not the full load detection sensor 44 is turned on.

  Here, if the full load detection sensor 44 is not ON (No in step S806), it is determined that the jam has not reached the position of the full load detection sensor 44 even when a predetermined time has elapsed, and the RAM 601 stores the delay jam. Store (step S807). If the full load detection sensor 44 is ON (Yes in step S806), it is determined in step S808 whether a predetermined time has elapsed since the fixing paper discharge sensor 33 was turned ON. If the predetermined time has not elapsed (No in step S808), the count is continued until the predetermined time elapses. Here, the predetermined time in step S808 is longer than the predetermined time in step S804. This is to detect whether or not a stay jam has occurred after detecting whether or not a delay jam has occurred.

Next, when it is determined in step S808 that the predetermined time has elapsed (Yes in step S808), the CPU 600 detects the state of the fixing paper discharge sensor 44 (step S809).
In step S810, it is determined whether the fixing paper discharge sensor 33 has been turned off.

  Here, if the fixing paper discharge sensor 33 is not OFF (No in step S810), it is determined that the jammed paper jam has not passed through the fixing paper discharge sensor 33 even if a predetermined time has elapsed, and the RAM 601 stores the jam. Store (step S811). When the fixing paper discharge sensor 33 is OFF (Yes in step S810), the leading edge of the sheet reaches the position of the full load detection sensor 44 within a predetermined time, and the trailing edge of the sheet is the fixing paper discharge sensor within a predetermined time. Therefore, it is determined that no jam has occurred in the transport path, and is stored in the RAM 601 (step S812).

  By performing the jam state determination process described above as needed during the image forming operation, the occurrence of a jam in the transport path is appropriately detected. When a jam occurs in the transport path, the user can improve the workability during the jam processing by forming a slack on the sheet in the transport path according to the jam state.

<Other embodiments>
In the first embodiment, when a stay jam occurs in the transport path, the downstream discharge roller pair 41 and the registration roller pair 15 are reversely rotated for a predetermined time, and when a delay jam occurs, the upstream pressure roller A slack is formed on the sheet in the conveyance path by rotating the pair 32 and the conveyance roller pair 14 in the forward direction for a predetermined time. However, even when a delay jam occurs, if the nipping of the sheet at the nip portion is not released due to the reverse rotation of the downstream discharge roller pair 41 and the registration roller pair 15, the downstream conveying means is rotated reversely. Also good. Specifically, even when a delay jam occurs, a slack may be formed on the sheet by rotating the discharge roller pair 41 and the registration roller pair 15 in the reverse direction.
By adopting such a configuration, regardless of the type of jam, the discharge roller pair 41 and the registration roller pair 15 as the downstream conveying means are rotated in the reverse direction to form a slack with respect to the sheet in the conveyance path. Thus, it is possible to improve the workability at the time of user jam processing.

  In the first embodiment, the reverse rotation and the normal rotation of the conveying unit are stopped depending on whether or not the sheet is conveyed by a predetermined distance when the slack is formed on the sheet. A configuration in which a sensor is provided and the reverse rotation and the normal rotation of the conveying unit are stopped immediately before the sheet is removed from the nip portion may be employed. By adopting such a configuration, it is possible to form a slack in which a user can easily insert a finger or a hand into a sheet in a conveyance path, and it is possible to improve workability at the time of the user's jam processing.

In the first embodiment, when forming a slack in a sheet, one of the two conveyance rollers that sandwich the sheet is driven to convey the sheet, and the other conveyance roller is conveyed. However, the sag may be formed on the sheet by rotating the upstream conveying roller in the forward direction and rotating the downstream conveying roller in the reverse direction. In this case, conveyance may be performed as long as the sheet is not released from the nip portions of the upstream and downstream conveyance rollers.
By adopting such a configuration, it is possible to perform the operation when forming the slack on the sheet in the conveyance path in a relatively short time, and it is possible to improve the workability at the time of the user jam processing. .

14 Conveying roller pair 15 Registration roller pair 31 Fixing film 32 Pressure roller 33 Fixing discharge sensor 41 Discharge roller pair 44 Full load detection sensor S1 / S2 Sheet

Claims (9)

A first conveying means capable of nipping and conveying the sheet;
A second conveying means provided upstream of the first conveying means in the sheet conveying direction and capable of nipping and conveying the sheet nipped and conveyed by the first conveying means;
Detecting means for detecting an abnormal sheet conveyance;
And a control unit that controls the first conveyance unit and the second conveyance unit in a direction in which a slack is formed in the sheet when a sheet conveyance abnormality is detected by the detection unit. A sheet conveying apparatus. The control means controls the first conveying means to convey the sheet in a direction opposite to the sheet conveying direction when an abnormality in conveying the sheet is detected by the detecting means. The sheet conveying apparatus according to 1. The control means controls the second conveying means so as to convey the sheet in the same direction as the sheet conveying direction when an abnormality in conveying the sheet is detected by the detecting means. Or the sheet conveying apparatus of Claim 2. 3. The sheet conveying apparatus according to claim 2, wherein the control unit stops the second conveying unit when an abnormality in conveying the sheet is detected by the detecting unit. The control unit stops the first conveyance unit when the detection unit detects a conveyance error of the sheet, and causes the second conveyance unit to convey the sheet in the same direction as the sheet conveyance direction. The sheet conveying device according to claim 1, wherein the sheet conveying device is controlled. The detection means includes
A first detection unit that is provided between the first conveyance unit and the second conveyance unit and detects a conveyance state of the sheet;
A second detection unit that is provided downstream of the first conveying unit in the sheet conveying direction and detects a conveying state of the sheet;
Determination means for determining from the detection results of the first detection unit and the second detection unit whether the sheet is staying or conveyance of the sheet is delayed,
The control means includes
When the determination unit determines that the sheet is staying, the second conveyance unit stops conveying the sheet, and the sheet is conveyed by a predetermined distance in a direction opposite to the sheet conveyance direction. 1 transport means,
When the determination unit determines that the conveyance of the sheet is delayed, the conveyance of the sheet by the first conveyance unit is stopped, and the sheet is conveyed by a predetermined distance in the same direction as the sheet conveyance direction. The sheet conveying apparatus according to any one of claims 1 to 5, wherein the second conveying unit is controlled. Developing means for forming a developer image on an image carrier, transfer means for transferring the developer image onto a sheet, fixing means for fixing the developer image transferred by the transfer means on the sheet, A discharge unit that discharges the sheet on which the developer image has been fixed by the fixing unit;
A sheet conveying device according to any one of claims 1 to 6, comprising:
The first conveying means is the fixing means,
The image forming apparatus, wherein the second transport unit is the discharge unit. Developing means for forming a developer image on an image carrier, transfer means for transferring the developer image in a sheet form, fixing means for fixing the developer image transferred by the transfer means in a sheet form, An image forming unit comprising: a discharging unit that discharges the sheet on which the developer image is fixed by the fixing unit;
A sheet conveying device according to any one of claims 1 to 6, comprising:
The first conveying unit is a registration roller that is provided upstream of the transfer unit in the sheet conveying direction and corrects the skew of the sheet.
The image forming apparatus, wherein the second conveyance unit is a conveyance roller that is provided upstream of the registration rollers in the sheet conveyance direction and conveys the sheet to the registration rollers. Developing means for forming a developer image on an image carrier, transfer means for transferring the developer image onto a sheet, fixing means for fixing the developer image transferred by the transfer means on the sheet, A discharge unit that discharges the sheet on which the developer image has been fixed by the fixing unit;
A sheet conveying apparatus according to any one of claims 6 to 8, comprising:
The first detection unit is a fixing discharge detection sensor that detects a sheet on which the developer image is fixed by the fixing unit.
The image forming apparatus, wherein the second detection unit is a full load detection sensor that detects a full load state of sheets discharged by the discharge unit.

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