JP4882568B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  As a conventional technique related to an image forming apparatus, Patent Document 1 describes a technique for controlling a transport roll so as to remove a sheet that has caused a sheet jam after detecting the sheet jam.

  Further, in Patent Document 2, after detecting a paper jam, an upstream (inside of the apparatus main body cover) attached to the side surface of the apparatus main body is linked with the operation (operation) of the user opening the upstream side. By driving the side conveying member and the downstream conveying member, the sheet is conveyed so as to form a loop between the conveying members, and the guide member is self-weighted in conjunction with the opening operation of the cover by the user. A technique is disclosed in which the paper conveyance path near the drawer unit is opened by swinging.

JP 2001-19231 A Japanese Patent Laid-Open No. 2005-77895

  According to the present invention, when a paper jam occurs at a position straddling two units, it is possible to avoid the tearing of the paper accompanying the operation of pulling out the unit without the user performing an operation such as opening the apparatus main body cover. It is an object of the present invention to provide an image forming apparatus that can be used.

The image forming apparatus according to claim 1, a main body fixing unit provided in a fixed state with respect to the image forming apparatus main body, a drawer unit provided so as to be drawable with respect to the image forming apparatus main body, and the main body fixing. A first sheet conveying means provided downstream of the boundary between the unit and the drawer unit in the sheet conveying direction; an upstream of the boundary between the main body fixing unit and the drawer unit in the sheet conveying direction; and A paper transport path is provided between the second paper transport means provided adjacent to the first paper transport means in the paper transport direction, and between the first paper transport means and the second paper transport means. and forming the the paper conveying direction of the downstream side movable member swingably supported around a fulcrum portion provided at one end of a pair of sheet conveying path formed in which the other fixing member the hand And wood, and a solenoid for operating the movable member to rotate around the fulcrum, when a paper jam occurs at a position across said main fixing unit and the drawer unit, upstream of the sheet conveyance direction The solenoid is driven to operate the movable member in a direction to open the paper transport path so that the paper transport path is widened toward the head, and after driving the solenoid, the paper is fed in a direction opposite to the paper transport direction. by driving the first sheet conveying means so pull back, is the sheet which is characterized in that to obtain Bei and conveyance control means for moving the sheet conveying path.

According to the image forming apparatus of the first aspect, when a paper jam occurs at a position straddling the main body fixing unit and the drawer unit, the paper jammed across the main body fixing unit and the drawer unit By pulling back in the direction opposite to the sheet conveying direction by driving one sheet conveying means, it is possible to avoid tearing of the sheet due to the operation of pulling out the unit without the user performing an operation such as opening the apparatus main body cover. it can. Further, when the sheet is pulled back in the direction opposite to the sheet conveyance direction by driving the first sheet conveyance unit, the movable member moves in a direction to open the sheet conveyance path, so that the sheet conveyance load applied to the first sheet conveyance unit. Can be reduced .

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a configuration example of an image forming apparatus according to an embodiment of the present invention. The illustrated image forming apparatus 1 is roughly configured to include a paper feeding unit 2, a drawer unit 3, and a paper reversing unit 4. Among these, the paper feeding unit 2 and the paper reversing unit 4 are provided in a fixed state with respect to the image forming apparatus main body (not shown). Therefore, both the paper feed unit 2 and the paper reversing unit 4 correspond to the main body fixing unit. The drawer unit 3 is provided so that it can be pulled out from the image forming apparatus main body.

  The image forming apparatus main body is constituted by an apparatus main body frame (not shown), for example. The paper feed unit 2 and the paper reversing unit 4 are fixedly attached to the image forming apparatus main body by screws or the like. The drawer unit 3 is attached to the image forming apparatus main body by a guide rail or the like so that it can be pulled out.

  A plurality (two in the illustrated example) of paper storage units 5 and 6 are incorporated in the paper supply unit 2. Each of the paper storage units 5 and 6 stores a predetermined number of papers (recording papers) used for image formation in a stacked state. Note that the number of paper storage units provided in the paper supply unit 2 may be one, or may be three or more.

  In the paper feed portion of the paper storage unit 5, a call roll 7 and a feed roll 8 are arranged as paper feed rolls. The calling roll 7 calls a sheet from the sheet storage unit 5 by rotating in contact with the top surface of the sheet stored in the sheet storage unit 5. The delivery roll 8 feeds out the sheets called up by the calling roll 7 one by one. Similarly, a calling roll 9 and a delivery roll 10 are arranged as a paper feed roll in the paper feed portion of the paper storage unit 6.

  Each of the paper feeding unit 2, the drawer unit 3, and the paper reversing unit 4 is formed with a paper conveyance path for conveying the paper. If this paper transport path is divided into a plurality of paper transport paths R1 to R4, the first paper transport path R1 is mainly a paper transport path for feeding paper, and the second paper transport path R2 is a main paper transport path R2. It becomes a paper transport path for image formation. The third paper transport path R3 is a paper transport path mainly for reversing the paper by the switchback method, and the fourth paper transport path R4 is a paper transport path mainly for refeeding the paper. It becomes.

  A plurality (two in the illustrated example) of transport rolls (roll pairs) 11 and 12 are provided inside the paper feed unit 2 as rolls for transporting paper. Each of the transport rolls 11 and 12 is disposed on the upstream side and the downstream side in the paper transport direction on the first paper transport path R1. That is, the transport roll 11 is disposed on the downstream side in the paper transport direction, and the transport roll 12 is disposed on the downstream side in the paper transport direction.

  A plurality (four in the illustrated example) of paper detection sensors 13 to 16 are provided inside the paper supply unit 2. Each of the paper detection sensors 13 to 16 is disposed on the first paper transport path R1 at a different position in the paper transport direction, and detects the paper being transported at each position.

  More specifically, in the paper transport direction, the paper detection sensor 13 is disposed between the delivery roll 8 and the transport roll 12 in the vicinity (downstream side) of the delivery roll 8, and the paper detection sensor 14 is connected to the delivery roll 10. Between the transport rolls 11, it is arranged in the vicinity (downstream side) of the delivery roll 10. Further, the paper detection sensor 15 is disposed between the transport roll 11 and the transport roll 12 in the vicinity (downstream side) of the transport roll 11, and the paper detection sensor 16 is disposed in the vicinity of the transport roll 12 (downstream side). ing.

  Inside the drawer unit 3, a plurality (six in the illustrated example) of transport rolls (roll pairs) 17 to 22 are provided as paper transport rolls. In addition, an image transfer unit 23 and an image fixing unit 24 are provided inside the drawer unit 3. Among these, the conveyance rolls 17, 18, and 19, the image transfer unit 23, and the image fixing unit 24 are arranged on the second sheet conveyance path R2, and the conveyance rolls 20, 21, and 22 are the fourth sheet conveyance. It arrange | positions on the path | route R4.

  In the second paper transport path R <b> 2, the transport roll 18 is disposed on the downstream side of the transport roll 17, and the image transfer unit 23 is disposed on the downstream side of the transport roll 18. Further, the image fixing unit 24 is disposed on the downstream side of the image transfer unit 23, and the transport roll 19 is disposed on the downstream side of the image fixing unit 24.

  The image transfer unit 23 and the image fixing unit 24 serve as an image forming unit that forms an image on a sheet being conveyed. Among these, the image transfer unit 23 is a part that transfers an image (toner image) onto a sheet. A belt support roll 26 and a transfer roll 27 are disposed in the image transfer unit 23 with the intermediate transfer belt 25 sandwiched therebetween. The intermediate transfer belt 25 rotates while holding a toner image transferred (primary transfer) from one or a plurality of (typically four) photosensitive drums (not shown). The belt support roll 26 supports the intermediate transfer belt 25 together with other rolls (not shown). The transfer roll 27 is for transferring the toner image held on the intermediate transfer belt 25 onto a sheet.

  FIG. 1 illustrates an example of a machine configuration for transferring a toner image held by an intermediate transfer belt 25 serving as an intermediate transfer member to a sheet in an electrophotographic image forming apparatus. However, an intermediate transfer member is used. Alternatively, a machine configuration in which the toner image is directly transferred from the photosensitive drum to the sheet may be used. Further, the image forming apparatus may employ a method other than the electrophotographic method (for example, an ink jet method, a thermal transfer method, etc.).

  The image fixing unit 24 is a part that fixes the toner image transferred by the image transfer unit 23 onto a sheet. In the image fixing unit 24, a heating roll 28 and a pressure roll 29 are arranged in contact with each other. The heating roll 28 is disposed so that it contacts the sheet surface on which the toner image is transferred by the image transfer unit 23, and the pressure roll 29 contacts the sheet surface on the opposite side with a predetermined pressure.

  On the other hand, in the fourth paper transport path R <b> 4, the transport roll 21 is disposed on the downstream side of the transport roll 20, and the transport roll 22 is disposed on the downstream side of the transport roll 21.

  Furthermore, a plurality (six in the illustrated example) of paper detection sensors 30 to 35 are provided inside the drawer unit 3. Among these, the paper detection sensors 30 to 32 are arranged at different positions in the paper transport direction on the second paper transport path R2, and detect the presence or absence of paper at each position. Further, the paper detection sensors 33 to 35 are arranged at different positions in the paper transport direction on the fourth paper transport path R4, and detect the paper being transported at each position.

  More specifically, in the paper transport direction, the paper detection sensor 30 is disposed between the transport roll 17 and the transport roll 18 in the vicinity (downstream side) of the transport roll 17, and the paper detection sensor 31 is connected to the transport roll 17. Between the conveyance rolls 18, it is arranged in the vicinity (upstream side) of the conveyance rolls 18. Further, the paper detection sensor 32 is arranged in the vicinity (downstream side) of the transport roll 19.

  On the other hand, the paper detection sensor 33 is disposed between the transport roll 20 and the transport roll 21 in the vicinity (downstream side) of the transport roll 20, and the paper detection sensor 34 is transported between the transport roll 21 and the transport roll 22. It is arranged near the roll 21 (downstream side). The paper detection sensor 35 is disposed between the transport roll 22 and the transport roll 17 in the vicinity (downstream side) of the transport roll 22.

  The paper reversing unit 4 is provided with a discharge roll 36, a transporting roll 37, and a reversing roll 38 as paper transporting rolls. The discharge roll 36 discharges a sheet on which an image has been formed into a sheet discharge container (not shown) (for example, a discharge tray). The discharge roll 36 is disposed at the end portion of the second paper transport path R2. The transport roll 37 is disposed on the upstream side of the reverse roll 38 on the third paper transport path R3. The reversing roll 38 is provided so as to be capable of rotating in both directions (forward rotation and reverse rotation).

  In addition, a plurality (three in the illustrated example) of paper detection sensors 39 to 41 that detect paper being conveyed at different positions in the paper conveyance direction are provided inside the paper reversing unit 4. Among these, the paper detection sensor 39 is disposed in the vicinity (upstream side) of the discharge roll 36 on the second paper transport path R2. The paper detection sensors 40 and 41 are provided on the third paper transport path R3. Among these, the paper detection sensor 40 is disposed in the vicinity (downstream side) of the transport roll 37 between the transport roll 37 and the reverse roll 38, and the paper detection sensor 41 is between the transport roll 37 and the reverse roll 38. It is arranged in the vicinity (upstream side) of the reversing roll 38.

  In the above apparatus configuration, the first paper transport path R1 is a paper transport path from the paper feed portion of each of the paper storage units 5 and 6 to the transport roll 17, and the second paper transport path R2 is the transport roll 17. To the discharge roll 36. Further, the third paper transport path R3 branches from the second paper transport path R2 on the downstream side of the transport roll 19 and extends downward, while the second paper transport path R3 extends from the paper detection sensor 40 toward the paper detection sensor 39. This is a sheet conveying path that merges with the sheet conveying path R2. The fourth paper transport path R4 branches from the third paper transport path R3 on the upstream side of the reversing roll 38 and the paper detection sensor 41, and sequentially passes through the transport rolls 20 and 21, and the final transport roll 22 Is a sheet conveyance path that returns to the conveyance roll 17.

  Next, an image forming operation performed by the image forming apparatus having the above configuration will be described. First, when a sheet to be subjected to image formation is stored in, for example, the sheet storage unit 5, it is stored in the sheet storage unit 5 by the rotation of the calling roll 7 and the delivery roll 8 corresponding to the sheet storage unit 5. The sheets are fed one by one in order from the top.

  The paper sent out from the paper storage unit 5 is transported along the first paper transport path R1 by the rotation of the transport roll 12, and proceeds from the first paper transport path R1 to the second paper transport path R2. It is sent to the transport roll 18 by the rotation of the transport roll 17. At this time, the rotation of the transport roll 18 is stopped before the paper is fed by the transport roll 17. For this reason, the leading edge of the sheet fed by the transport roll 17 abuts on the transport roll 18 in a rotation stopped state. Further, by feeding a predetermined amount of paper by the transport roll 17 in this abutting state, the paper is slacked in a loop shape before the transport roll 18 (upstream side), that is, the paper skew is corrected, In this state, the paper is temporarily stopped.

  Thereafter, the conveyance roll 18 starts to rotate in accordance with the timing at which the toner image held on the intermediate transfer belt 25 reaches the image transfer unit 23. As a result, the skew-corrected paper is sent to the image transfer unit 23 as the transport roll 18 rotates. In the image transfer unit 23, the sheet fed by the transport roll 18 moves so as to pass through a facing portion (image transfer position) between the intermediate transfer belt 25 and the transfer roll 27. At this time, the toner image on the intermediate transfer belt 25 is transferred to the first surface of the paper by the transfer roller 27 applying a charge having a polarity opposite to that of the toner. Incidentally, the transport roll 17 for feeding paper to the transport roll 18 is also called a pre-registration roll. Further, the transport roll 18 that feeds the paper to the image transfer unit 23 is also called a registration roll.

  Thereafter, the sheet is fed into the image fixing unit 24 where the toner image is fixed on the first surface of the sheet by the heating action by the heating roll 28 and the pressing action by the pressure roll 29. Next, the sheet sent out from the image fixing unit 24 is sent to the discharge roll 36 by the rotation of the transport roll 19 and is discharged to the sheet discharge storage unit (discharge tray or the like) by the rotation of the discharge roll 36. The above operation is applied in a mode for forming an image on one side of a sheet (single-sided image forming mode).

  On the other hand, when operating in a mode in which images are formed on both sides of a sheet (double-sided image forming mode), the traveling direction of the sheet conveyed by the rotation of the conveying roll 19 on the downstream side of the image fixing unit 24 is illustrated. The sheet is guided to the third sheet conveyance path R3 by the conveyance path switching member that does not, and the sheet is fed to the reverse roll 38 by the rotation of the conveyance roll 37 there. Next, when the trailing edge of the sheet has passed the branch position to the fourth sheet conveyance path R4, the rotation direction of the reversing roll 38 is reversed (switched from the normal rotation to the reverse rotation), thereby the third sheet. The sheet is switched back on the conveyance path R3 and sent to the fourth sheet conveyance path R4. Whether the trailing edge of the sheet has passed the branch position to the fourth sheet conveyance path R4 is determined based on the output signal of the sheet detection sensor 41.

  Next, after the paper is transported along the fourth paper transport path R <b> 4 by the rotation of the transport rolls 20, 21, and 22, the paper is again sent to the transport roll 17. Thereafter, after the toner image is transferred and fixed on the second surface of the paper in the same procedure as described above, the paper is discharged by the rotation of the discharge roll 36 as in the single-sided image forming mode.

  At that time, when the paper is discharged after being turned upside down, the traveling direction of the paper conveyed by the rotation of the conveyance roll 19 on the downstream side of the image fixing unit 24 is changed by a conveyance path switching member (not shown) in the same manner as described above. 3, the sheet is fed to the reverse roll 38 by the rotation of the conveyance roll 37. Next, when the trailing edge of the sheet has passed the detection position of the sheet detection sensor 40, the rotation direction of the reversing roll 38 is reversed (switched from the normal rotation to the reverse rotation), thereby the third sheet. The sheet is switched back on the conveyance path R3 and returned to the second sheet conveyance path R2, and discharged by the rotation of the discharge roll 36.

  FIG. 2 is a schematic diagram showing a configuration near the boundary between the paper feeding unit 2 and the drawer unit 3 in the image forming apparatus according to the embodiment of the present invention. In FIG. 2, the transport roll 12 provided in the paper feed unit 2 and the transport roll 17 provided in the drawer unit 3 are arranged in a positional relationship adjacent to each other in the paper transport direction. Accordingly, the sheet conveyed along the first sheet conveyance path R <b> 1 described above is transferred from the conveyance roll 12 to the conveyance roll 17. Moreover, the conveyance roll 17 is provided so that rotation (forward rotation, reverse rotation) is possible bidirectionally.

  Between the two transport rolls 12 and 17, a pair of paper transport path forming members 42 and 43 that form the first paper transport path R1 are provided. The pair of paper transport path forming members 42 and 43 are attached to the drawer unit 3 side. Of the pair of paper transport path forming members 42, 43, one paper transport path forming member 42 is a fixed member fixed to the drawer unit 3, and the other paper transport path forming member 43 is the drawer unit 3. It is a movable member that is supported in a swingable manner. One end (upper end) of the movable member 43 is supported so as to be rotatable around a fulcrum 44 provided in the drawer unit 3.

  In addition, the movable member 43 is urged in a direction in which the paper conveyance path is closed (a clockwise direction around the fulcrum portion 44 in the example) by an urging member 45 made of, for example, a tension coil spring. During normal paper conveyance, the movable member 43 is urged by the urging member 45 so that the paper conveyance path is held in a closed state. The normal paper conveyance means a state in which the paper is normally conveyed without causing an abnormality such as paper jam in the above-described image forming operation. When the paper conveyance path is closed by the urging force of the urging member 45, the position of the movable member 43 is regulated by a stopper (not shown) so that the movable member 43 faces the fixed member 42 with a predetermined gap. It becomes the composition which is done. The predetermined gap is a gap equivalent to the gap G of the sheet conveyance path formed in the vicinity (upstream side and downstream side) of the conveyance roll 12 on the sheet feeding unit 2 side.

  The biasing member 45 may be directly attached to the movable member 43, or may be indirectly attached via an intermediate member (not shown). Further, the urging member 45 may be configured by a spring member other than the tension coil spring (for example, a compression coil spring or a torsion coil spring), or may be configured by an elastic member other than the spring member (for example, a rubber material). Good.

  FIG. 3 is a block diagram showing a part of the control configuration of the sheet conveying system of the image forming apparatus according to the embodiment of the present invention. The conveyance control unit 46 controls conveyance of a sheet to be image-formed. In addition to the paper detection sensor 16 and the paper detection sensor 30 described above, a paper transport motor 47 and a paper transport motor 48 are connected to the transport control unit 46.

  The output signals of the paper detection sensors 16 and 30 are configured to be taken into the conveyance control unit 46 individually. The output signals of the paper detection sensors 16 and 30 are turned on when a paper is detected on the paper transport path, and are turned off when no paper is detected on the paper transport path. Therefore, for example, when the leading edge of the paper passes the detection position of the paper detection sensor 16 on the first paper conveyance path R1, the output signal of the paper detection sensor 16 is switched from the OFF state to the ON state, and then the paper detection sensor 16 When the trailing edge of the paper passes through this detection position, the output signal of the paper detection sensor 16 switches from the on state to the off state. The sheet detection operation by the sheet detection sensor 16 is similarly performed by other sheet detection sensors provided in each unit (2, 3, 4) of the image forming apparatus 1 including the sheet detection sensor 30.

  The paper transport motors 47 and 48 are configured using stepping motors. The paper transport motor 47 is a drive source for rotating the transport roll 12, and the paper transport motor 48 is a drive source for rotating the transport roll 17. The drive state of each of the paper transport motors 47 and 48 is individually controlled by the transport control unit 46.

  FIG. 4 is a flowchart illustrating an example of a sheet conveyance control process performed by the image forming apparatus according to the embodiment of the present invention. First, when the conveyance control unit 46 detects the occurrence of a paper jam during the image forming operation described above, the conveyance of the paper by the conveyance rollers 12 and 17 is stopped by stopping the driving of the paper conveyance motors 47 and 48 ( Steps S1, S2).

  Whether or not a paper jam has occurred is determined, for example, by whether or not each paper detection sensor has detected the passage of the paper (passing the leading edge and passing the trailing edge) by a predetermined timing. That is, if the paper detection sensor detects the passage of paper by a predetermined timing, it is determined that no paper jam has occurred, and if the paper detection sensor does not detect the passage of paper by the predetermined timing. It is determined that a paper jam has occurred. The predetermined timing is defined for each sheet detection sensor according to the sheet length in the sheet conveyance direction.

  Next, the transport control unit 46 checks whether or not a paper jam has occurred at a position straddling the paper feed unit 2 and the drawer unit 3 (step S3), and a paper jam has occurred at a position straddling the two units. If not, the process ends. As illustrated in FIG. 1, a state in which a paper jam has occurred at a position straddling the paper feed unit 2 and the drawer unit 3 refers to a conveyance roll 17 on the drawer unit 3 side from the conveyance roll 12 on the paper feed unit 2 side. Is a state in which the paper 49 is stopped across the section of the paper conveyance path leading to.

  When the sheet 49 is stopped in the above-described state, the leading end of the sheet 49 is positioned downstream of the transport roll 17 and the rear end of the sheet 49 is positioned upstream of the transport roll 12. The transport control unit 46 determines that a paper jam has occurred at a position straddling the paper feed unit 2 and the drawer unit 3 based on the fact that the output signals of the paper detection sensors 16 and 30 are both on. However, the criterion for determining whether or not a paper jam has occurred at a position straddling the paper feeding unit 2 and the drawer unit 3 is not limited to this.

  For example, the conveyance control unit 46 determines the sheet conveyance distance from when the sheet detection sensor 16 detects the passage of the leading edge of the sheet until the conveyance of the sheet by the conveyance rolls 12 and 17 is stopped in step S2, for example, a sheet conveyance motor. When the number of drive pulses 47 and 48 is counted and the sheet conveyance distance obtained by the measurement is longer than the conveyance path length from the sheet detection sensor 16 to the conveyance roll 17, the sheet feeding unit 2. In some cases, it is determined that a paper jam has occurred at a position straddling the drawer unit 3.

  Further, if necessary, paper detection sensors are provided on the upstream side of the transport roll 12 and the upstream side of the transport roll 17, and based on the output signals of those paper detection sensors and the output signals of the paper detection sensors 16 and 30. In some cases, it is determined whether a paper jam has occurred at a position between the paper feeding unit 2 and the drawer unit 3.

  When the conveyance control unit 46 determines that a paper jam has occurred at a position straddling the paper feed unit 2 and the drawer unit 3, the conveyance control unit 46 drives the paper conveyance motor 48 to start the reverse rotation of the conveyance roll 17 (step S4). . As a result, the paper sandwiched between the transport rolls 17 is pulled back in the direction opposite to the paper transport direction. At this time, since the conveyance control unit 46 does not drive the paper conveyance motor 47, the conveyance roll 12 on the paper feed unit 2 side is held in a stopped state.

  Further, when the transport control unit 46 pulls back the paper by the reverse rotation of the transport roll 17, the transport speed of the paper by the transport roll 17 (in other words, the rotational speed of the transport roll 17) is made lower than that during normal paper transport. Set. Further, the conveyance control unit 46 sets the drive current value of the sheet conveyance motor 28 to a higher value than that during normal sheet conveyance. Incidentally, in order to set the sheet conveyance speed by the conveyance roll 17 to be lower than that during normal sheet conveyance, the frequency of drive pulses (number of pulses per second) supplied to the sheet conveyance motor 48 is set to normal sheet conveyance. It may be set to a value lower than the hour.

  Next, after the output signal of the paper detection sensor 30 is turned off, the transport control unit 46 stops driving the paper transport motor 48 and stops the reverse rotation of the transport roll 17 after a predetermined time (step S5, S6). The predetermined time is set according to the time required for the leading edge of the paper pulled back by the reverse rotation of the transport roll 17 to pass through the transport roll 17 after passing the detection position of the paper detection sensor 30.

  Thus, when a paper jam occurs at a position straddling the paper feed unit 2 and the drawer unit 3, the transport roll 17 is rotated in the reverse direction so that the paper is pulled back in the direction opposite to the paper transport direction. The leading edge of the sheet pulled back by the reverse rotation is in a state where it has passed through the transport roll 17. For this reason, the paper that has stopped at a position straddling the paper feed unit 2 and the drawer unit 3 is released from the nipping by the conveyance roll 17 on the drawer unit 3 side and is nipped by the conveyance roll 12 on the paper feed unit 2 side. It becomes a state. Therefore, even if the user who uses the image forming apparatus 1 operates to pull out the drawer unit 3 from the main body of the image forming apparatus, the sheet is not torn at the boundary between the paper feed unit 2 and the drawer unit 3.

  Further, when the paper 49 is pulled back by the reverse rotation of the transport roll 17 as described above, the paper 49 is pushed into the paper transport path between the transport roll 12 and the transport roll 17. For this reason, when the distance to which the paper 49 is pulled back is long, the paper 49 is slackened in the paper transport path and deformed into a bellows shape. Then, of the fixed member 42 and the movable member 43 that form the paper conveyance path between the conveyance roll 12 and the conveyance roll 17, the movable member 43 is pushed by the paper 49 that is pulled back by the reverse rotation of the conveyance roll 17. Swings in the direction to open the paper transport path.

  For this reason, in a section from the transport roll 12 to the transport roll 17, a space necessary for accommodating the paper 49 pulled back by the reverse rotation of the transport roll 17 is secured by the swing of the movable member 43. If the movable member 43 does not move in the same manner as the fixed member 42, the paper 49 pulled back by the reverse rotation of the transport roll 17 can be pushed into a limited narrow space. For this reason, the sheet conveyance load applied to the conveyance roll 17 and the sheet conveyance motor 48 increases.

  In the above-described embodiment, the movable member 43 is swingably supported around the fulcrum portion 44 provided in the drawer unit 3, but other than this, for example, as shown in FIG. The one end (upper end) of the movable member 43 is fixed by the fulcrum portion 44 provided in the drawer unit 3, and the movable member 43 is made of a resin film, for example, so that it is pulled back by the reverse rotation of the transport roll 17. Alternatively, the movable member 43 may be configured to move in a direction to open the paper conveyance path by being bent and deformed by being pushed by the paper 49.

  Further, as shown in FIG. 6, the movable member 43 is swingably supported around the fulcrum portion 44 and a solenoid 50 for operating the movable member 43 in the direction to open the paper conveyance path is provided. When the paper 49 is pulled back by reverse rotation, the conveyance control unit 46 may drive the solenoid 50 so that the movable member 43 moves in a direction to open the paper conveyance path. In this case, the timing at which the conveyance control unit 46 drives the solenoid 50 may be set before the conveyance control unit 46 drives the paper conveyance motor 48 and starts the reverse rotation of the conveyance roll 17 in step S4. Further, as a drive source for operating the movable member 43, drive means (for example, a motor) other than the solenoid may be used.

  In the above embodiment, one of the pair of paper transport path forming members 42 and 43 is a movable member. However, both of the pair of paper transport path forming members 42 and 43 may be movable members.

  Further, when a paper jam occurs at a position straddling the paper feeding unit 2 and the drawer unit 3, the leading edge of the paper causing the paper jam is located downstream of the transport roll 18 or the like. In response to this, both the transport roll 17 and the transport roll 18 may be rotated in reverse by driving the paper transport motor by the transport control unit 46.

  Further, when a paper jam occurs at a position straddling the drawer unit 3 and the paper reversing unit 4 (a section from the transport roll 19 to the discharge roll 36 or the transport roll 37, a section from the reverse roll 38 to the transport roll 20, etc.) As a countermeasure against the above, a configuration similar to the above may be adopted.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration in the vicinity of a boundary portion between a paper feeding unit and a drawer unit in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram illustrating a part of a control configuration of a paper transport system of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an example of a sheet conveyance control process performed by the image forming apparatus according to the embodiment of the present invention. It is the schematic which shows other embodiment of this invention. It is the schematic which shows other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Paper feed unit, 3 ... Drawer unit, 4 ... Paper reversing unit, 12, 17 ... Conveyance roll, 16, 30 ... Paper detection sensor, 42 ... Paper conveyance path formation member (fixing member), 43: Paper transport path forming member (movable member), 46: Transport control unit, 47, 48 ... Paper transport motor, 49 ... Paper, 50 ... Solenoid, R1-R4 ... Paper transport path

Claims (1)

A main body fixing unit provided in a fixed state with respect to the image forming apparatus main body;
A drawer unit provided so as to be capable of being pulled out from the image forming apparatus main body;
First paper transport means provided downstream of the boundary between the main body fixing unit and the drawer unit in the paper transport direction;
A second sheet conveying means provided upstream of the boundary between the main body fixing unit and the drawer unit in the sheet conveying direction and adjacent to the first sheet conveying means in the sheet conveying direction;
And forming a paper transportation path between said first sheet conveying means and said second sheet conveying means, oscillating about a fulcrum portion provided a hand on the downstream side of the one end of the sheet conveying direction A pair of paper transport path forming members having a freely supported movable member and the other fixed member ;
A solenoid that operates the movable member to rotate about the fulcrum portion;
When a paper jam occurs at a position straddling the main body fixing unit and the drawer unit, the movable member moves in the direction to open the paper conveyance path so that the paper conveyance path becomes wider toward the upstream side in the paper conveyance direction. The solenoid is driven to operate a member, and after the solenoid is driven , the first paper transporting unit is driven to pull back the paper in a direction opposite to the paper transport direction, and the paper is transported to the paper transport path. image forming apparatus characterized by obtaining Bei and conveyance control means for moving the.

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