JP4992727B2 - Paper conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying device and an image forming apparatus.

  Some image forming apparatuses such as copying machines and printers form an image on a sheet after correcting the skew of the sheet on the sheet conveyance path. As a method for correcting the inclination of the paper, a method in which the front end of the paper is abutted against a reference member and the paper is bent in a loop shape (hereinafter referred to as a “front end abutting method”) is known.

  As a conventional technique that employs the leading edge abutting method, a portion in which a gap in the sheet conveyance path is secured in advance in preparation for loop formation of the sheet upstream of the reference member in the sheet conveyance direction (hereinafter referred to as “expansion part”). And a configuration in which the paper is bent in a loop shape at the expanded portion when the front end of the paper is abutted against the reference member (for example, see Patent Documents 1 to 3). ).

JP-A-5-124753 JP-A-6-64792 JP-A-7-267427

  In the above prior art, since the paper reaches the reference member via the widening portion, if the gap in the paper transport path is wide at the widening portion, the paper traveling direction is not stable, and the paper seat Prone to bending and jamming. In particular, the tendency becomes conspicuous in a sheet with low stiffness (for example, a thin sheet or a sheet containing moisture). Further, in the configuration in which the expanding portion is provided, the driving force for pressing the leading edge of the paper against the reference member is obtained by the reaction force accompanying the loop formation of the paper. For this reason, for example, a sheet with low stiffness may not provide the driving force necessary for tilt correction. Further, in the technique described in Patent Document 3, means for pressing the paper loop from behind is provided. However, depending on the type of paper, the widened portion is too wide or too narrow, and a desired driving force is obtained. In some cases, it could not be obtained.

  An object of the present invention is to reliably guide the leading edge of a sheet to a reference member regardless of the type of the sheet, and to abut the leading edge of the sheet against the reference member with a sufficient driving force required for tilt correction. It is to provide a mechanism that can do this.

  According to the first aspect of the present invention, there is provided a sheet conveying unit that conveys a sheet along a sheet conveying path, a reference member on which a leading end of the sheet is abutted on the sheet conveying path, and an upstream of the reference member in the sheet conveying direction And a sheet conveyance guide member that is provided in a portion where the sheet is bent by abutment with the reference member and operates in an opening direction that widens the gap of the sheet conveyance path and a closing direction that narrows the gap, and the sheet conveyance guide An urging means for urging the member in the closing direction; a restricting means for restricting an opening operation of the sheet conveying guide member in a state where the sheet conveying guide member is fixed at a closed position; and a leading end of the sheet is the sheet conveying The restricting means restricts the opening operation of the paper transport guide member before passing the guide member, and after the leading edge of the paper passes the paper transport guide member, the restricting means opens the opening. A sheet conveying apparatus characterized by comprising a control means for releasing the regulation of operation.

  According to a second aspect of the present invention, in the paper conveying device according to the first aspect, when the drive source that is rotationally driven in both directions and the drive source is rotationally driven in the first direction, the rotational driving force is applied to the paper. A first power transmission mechanism that transmits to the conveying member; and a second power transmission mechanism that transmits the rotational driving force to the restricting means when the drive source is rotationally driven in the second direction. Features.

  According to a third aspect of the present invention, a sheet conveying unit that conveys a sheet along a sheet conveying path, and an image is formed on the sheet conveyed by the sheet conveying unit, and provided in the middle of the sheet conveying path. An image forming unit that records an image on the sheet at an image recording position; a reference member that is provided upstream of the image recording position in the sheet conveying direction; and a front end of the sheet that abuts on the sheet conveying path; A sheet that is provided upstream of the reference member in the sheet conveyance direction and in a portion where the sheet is bent by abutting against the reference member, and operates in an opening direction that widens the gap of the sheet conveyance path and a closing direction that narrows the gap. A conveying guide member, an urging means for urging the sheet conveying guide member in the closing direction, and an opening movement of the sheet conveying guide member in a state where the sheet conveying guide member is fixed at a closed position. Before the leading edge of the sheet passes through the sheet conveying guide member, the opening operation of the sheet conveying guide member is regulated by the regulating means, and the leading edge of the sheet is the sheet conveying guide member. And a control unit that controls to release the restriction of the opening operation by the restriction unit after passing through the image forming apparatus.

  According to the first and third aspects of the invention, regardless of the type of paper, the leading edge of the paper can be reliably guided to the reference member, and the paper can be driven with sufficient thrust necessary for inclination correction. The tip can be abutted against the reference member. For this reason, it is possible to improve the correction capability of the inclination correction while preventing the occurrence of buckling, jamming, and the like of the paper.

  According to the second aspect of the present invention, it is possible to operate the restricting means while sharing the manual feed source.

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

  FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus to which the present invention is applied. The illustrated image forming apparatus is an image forming apparatus that forms an image on a sheet by electrophotography. The image forming apparatus includes a sheet conveying apparatus for conveying a sheet to be image formed, and an image forming unit that forms an image on the sheet conveyed by the sheet conveying apparatus.

  The image forming apparatus includes two sheet storage units 1 and 2. The two paper storage units 1 and 2 are arranged in a vertical positional relationship. Each of the paper storage units 1 and 2 stores a predetermined number of sheets (a plurality of sheets) in a stacked state. The size of the paper stored in the paper storage unit 1 is smaller than the size of the paper stored in the paper storage 2.

  In the paper feed portion of the upper paper storage unit 1, a call roll 3 and a feed roll 4 are arranged as paper feed rolls. The call roll 3 is for calling the sheets stored in the sheet storage unit 1 in order from the top sheet. The delivery roll 4 separates and feeds the sheets called up by the calling roll 3 one by one. Similarly, a calling roll 5 and a delivery roll 6 are also arranged as a paper feeding roll in the paper feeding portion of the lower paper storage unit 2.

  In addition, in the image forming apparatus main body 100, a sheet conveying unit that is a main component of the sheet conveying apparatus is provided. The sheet conveying means conveys the sheet along the sheet conveying path. The paper transport path is formed using a paper transport guide member provided to guide the paper traveling direction. On the paper conveyance path, a plurality of conveyance rolls (conveyance members) 7 to 19 constituting a paper conveyance unit are provided. Each of the conveying rolls 7 to 19 conveys a sheet by applying a conveying force to the sheet by rotating with the sheet sandwiched between a pair of rolls. Among these, the conveyance rolls 14 and 15 are provided in the reverse conveyance unit 101, and the conveyance rolls 16 to 19 are provided in the refeed conveyance unit 102. The reverse conveyance unit 101 and the refeed conveyance unit 102 are provided as conveyance units for double-sided image formation.

  Here, when the paper transport path is divided into a plurality of paper transport paths R1 to R6, the first paper transport path R1 and the second paper transport path R2 are divided between the transport roll 8 and the transport roll 9. Has been. The third paper transport path R3 branches off from the second paper transport path R2 on the downstream side of the transport roll 11. The third paper transport path R3 and the fourth paper transport path R4 are divided between the transport roll 14 and the transport roll 15. The fifth paper transport path R5 branches from the fourth paper transport path R4 between the transport roll 14 and the transport roll 15. The fifth paper transport path R5 joins the second paper transport path R2 on the upstream side of the transport roll 9. The sixth paper transport path R6 branches from the third paper transport path R3 between the transport roll 13 and the transport roll 14. The sixth paper transport path R6 joins the second paper transport path R2 on the upstream side of the transport roll 12.

  The first paper transport path R1 is a paper feed transport path for feeding the paper stored in the paper storage units 1 and 2 toward the image forming means, and the second paper transport path R2 is the image forming means. The image forming conveyance path for conveying the sheet so as to pass through the image recording position P. Further, the third paper transport path R3 is a relay transport path that relays between the second paper transport path R2 and the fourth paper transport path R4, and the fourth paper transport path R4 reverses the front and back of the paper. Is the reverse conveyance path. The fifth paper transport path R5 is a re-feed paper transport path for feeding the paper reversed in the fourth paper transport path R4 toward the image forming unit again, and the sixth paper transport path R6. Is a reversal discharge conveyance path for reversing and discharging the image-formed paper.

  The transport rolls 7 and 8 are disposed on the first paper transport path R1, and the transport rolls 9 to 12 are disposed on the second paper transport path R2. The transport rolls 13 and 14 are disposed on the third paper transport path R3, and the transport roll 15 is disposed on the fourth paper transport path R4. The transport rolls 16 to 19 are arranged on the fifth paper transport path R5.

  Further, the transport roll 7 is disposed on the upstream side of the transport roll 8 on the first paper transport path R1. The transport roll 8 is disposed on the downstream side of the transport roll 7 on the first paper transport path R1. These transport rolls 7 and 8 respectively receive the paper supplied from the paper storage unit 1 by the paper supply rolls 3 and 4 and the paper supplied from the paper storage unit 2 by the paper supply rolls 5 and 6. It is conveyed along the first paper conveyance path R.

  The transport roll 9 is arranged on the upstream side of the transport roll 10 on the second paper transport path R2. The transport roll 9 is a sheet transported from the first sheet transport path R1 to the second sheet transport path R2 by the transport roll 8, or the fifth sheet transport path R5 to the second sheet transport path by the transport roll 19. The sheet conveyed to R2 is conveyed toward the conveyance roll 10. The transport roll 9 and the transport roll 10 are arranged in a positional relationship adjacent to each other in the paper transport direction. The transport roll 10 is a roll that feeds the paper transported by the transport roll 9 toward the image recording position P. The resist roll 10 is provided on the upstream side of the image recording position P as a reference member. The image recording position P is provided in the middle of the paper conveyance path, and refers to a position where an image is actually recorded on the paper (a toner image is transferred in this embodiment). In the following description, the transport roll 10 is referred to as a resist roll, and the transport roll 9 is referred to as a pre-registration roll.

  In the paper transport direction, an inclination correction unit 20 is provided on the paper transport path from the pre-registration roll 9 to the registration roll 10 (upstream of the registration roll 10). The inclination correction unit 20 is a part that corrects the inclination of the sheet by the leading end abutting method on the second sheet conveyance path R2. In the inclination correction unit 20, the second sheet conveyance path R <b> 2 is formed in a curved state so that the sheet traveling direction is bent by approximately 90 ° in the conveyance section from the pre-registration roll 9 to the registration roll 10.

  The inclination correction unit 20 corrects the inclination (posture) of the sheet by using the registration roll 10 as a reference member and abutting the leading end of the sheet against the registration roll 10 to bend the sheet in a loop shape. The reference member is a member used to align the front end of the sheet in the direction perpendicular to the sheet conveyance direction within the sheet conveyance surface. Here, the resist roll 10 is used as a reference member as an example. However, for example, a shutter member provided in front of the resist roll 10 may be used as the reference member, although not shown, instead of the resist roll 10.

  In the paper transport direction, a first paper detection sensor S1 is provided on the downstream side of the pre-registration roll 9, and a second paper detection sensor S2 is provided on the upstream side of the registration roll 10. The first paper detection sensor S1 and the second paper detection sensor S2 detect the passage of paper (passing the leading edge and passing the trailing edge) in the middle of the second paper conveyance path R2 from the pre-registration roll 9 to the registration roll 10, respectively. Is. The first paper detection sensor S1 is disposed in the vicinity of the pre-registration roll 9, and the second paper detection sensor S2 is disposed in the vicinity of the registration roll 10.

  Each of the sheet detection sensors S1 and S2 is configured using, for example, a reflection type photosensor in which a light emitting element and a light receiving element are arranged on a common sensor surface. In this case, each of the sheet detection sensors S1 and S2 is in an on state when a sheet is present at a position (hereinafter also referred to as “detection position”) that is close to and opposed to its own sensor surface, and when there is no sheet. Is turned off. Accordingly, each of the sheet detection sensors S1 and S2 switches from the off state to the on state when the leading edge of the sheet passes through the corresponding detection position, and then when the trailing edge of the sheet passes through the detection position. Switches from an on state to an off state. The leading edge of the paper refers to a paper edge that is arranged on the paper conveyance path facing the downstream side in the paper conveyance direction, and the trailing edge of the paper is arranged on the paper conveyance path that faces the upstream side in the paper conveyance direction. The edge of the paper. As the sheet detection sensors S1 and S2, a transmissive photosensor may be used, or another sensor may be used.

  An image transfer unit 21 is provided on the downstream side of the registration roll 10 in the second paper transport path R2. The image transfer unit 21 is a part that transfers an image (toner image) onto a sheet. A belt support roll 23 and a transfer roll 24 are disposed in the image transfer unit 21 with the intermediate transfer belt 22 interposed therebetween. The intermediate transfer belt 22 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 23 supports the intermediate transfer belt 22 together with other rolls (not shown). The transfer roll 24 transfers the toner image held on the intermediate transfer belt 22 to the sheet by applying a charge having a polarity opposite to that of the toner to the sheet with the sheet sandwiched between the belt support roll 23. is there.

  FIG. 1 illustrates a machine configuration in which a toner image held by an intermediate transfer belt 22 serving as an intermediate transfer body is transferred to a sheet in an electrophotographic image forming apparatus. However, an intermediate transfer body 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 vacuum transport unit 25 includes an endless transport belt 26 and two rolls 27 and 28 that support the transport bell 26. The vacuum conveyance unit 25 places a sheet on the conveyance belt 26 and sucks the lower surface of the sheet (the surface opposite to the surface on which the toner image is transferred) by a vacuum method, and the sheet is conveyed according to the traveling of the conveyance belt 26. It is to be transported.

  A fixing device 29 is disposed on the downstream side of the vacuum transport unit 25. The fixing device 29 fixes the toner image transferred onto the paper by the image transfer unit on the paper surface of the paper by a heating and pressurizing method. The heating roller 30 is heated to a predetermined temperature (fixing temperature) by a heater or the like, A pressure roll 31 that contacts the heating roll 30 at a predetermined pressure is provided.

  The transport roll 11 is disposed on the downstream side of the fixing device 29 on the second paper transport path R2. On the downstream side of the transport roll 11, the third paper transport path R3 branches obliquely downward from the middle of the second paper transport path R2, and a transport switching member (not shown) is provided at this branched portion. The conveyance switching member moves the paper conveyed by the conveyance roll 11 in the first direction toward the conveyance roll 12 (the direction along the second sheet conveyance path R2) and the second direction toward the conveyance roll 13. The direction is switched to one of the three directions (the direction of branching to the third paper transport path R3).

  The transport roll 12 is disposed at the end portion of the second paper transport path R2. The transport roll 12 is a roll (hereinafter also referred to as a “discharge roll”) that discharges an image-formed sheet to a sheet discharge storage unit (for example, a discharge tray) (not shown).

  The transport roll 13 transports the paper transported by the transport roll 11 toward the transport roll 14 disposed on the downstream side of the transport roll 13. The transport roll 14 is disposed on the downstream side of the transport roll 13 on the third paper transport path R3. The transport roll 14 is provided so as to be rotatable (forward / reverse) in both directions.

  The transport roll 15 is disposed on the downstream side of the transport roll 14 in the paper transport direction. Similar to the transport roll 14, the transport roll 15 is provided so as to be capable of rotating in both directions (forward / reverse rotation). Each of the transport roll 14 and the transport roll 15 is a roll (hereinafter, also referred to as “reversing roll”) that reverses the paper being transported by the switchback method.

  The transport rolls 16 to 19 are arranged in order from the upstream side to the downstream side in the paper transport direction. That is, in the fifth paper transport path R5, the transport roll 17 is disposed on the downstream side of the transport roll 16, the transport roll 18 is disposed on the downstream side of the transport roll 17, and the transport roll 19 is on the downstream side of the transport roll 18. Has been placed.

  Next, the operation (image forming operation) of the image forming apparatus according to the embodiment of the present invention will be described. First, when starting an image forming operation, a sheet to be subjected to image formation is fed from a sheet container designated by a user or automatically selected sheet container. For example, assuming that the user-specified paper storage unit or the automatically selected paper storage unit is the upper paper storage unit 1, the paper storage unit 1 can store the paper by rotating the calling roll 3 and the delivery roll 4 corresponding to the paper storage unit 1. The sheet is sent out from the section 1 to the first sheet conveyance path R1.

  Thus, the sheet fed from the sheet storage unit 1 is transported to the downstream side in the sheet transport direction by the rotation of the transport roll 8 and sent to the pre-registration roll 9. Next, the sheet is fed into the registration roll 10 according to the rotation of the pre-registration roll 9. At this time, the inclination correction unit 20 corrects the inclination of the paper by abutting against the registration roll 10.

  More specifically, the registration roll 10 is brought into a rotation stopped state before the paper is fed by the pre-registration roll 9. Therefore, the leading edge of the sheet fed by the pre-registration roll 9 is abutted against the registration roll 10 in a rotation stopped state. Further, by feeding the paper by a predetermined amount by the pre-registration roll 9 in this abutting state, the paper is bent in a loop shape by the inclination correcting unit 20, that is, the paper inclination is corrected. The paper pauses. At this time, the inclination correction unit 20 is disposed outside the curved conveyance curve among the sheet conveyance guide members 35 to 37 that form the second sheet conveyance path R <b> 2 between the pre-registration roll 9 and the registration roll 10. The sheet conveyance guide member 35 is configured to be pushed by the sheet bent in a loop by being abutted against the registration roll 10 and to escape (displace) to the outside.

  Thereafter, the registration roll 10 starts rotating in accordance with the timing at which the toner image held on the intermediate transfer belt 22 reaches the image recording position P of the image transfer unit 21. As a result, the sheet is fed into the image transfer unit 21 according to the rotation of the registration roll 10. In the image transfer unit 21, the sheet fed by the registration roll 10 moves so as to pass through a facing portion between the intermediate transfer belt 22 and the transfer roll 24 supported by the belt support roll 23. At this time, the toner image on the intermediate transfer belt 22 is transferred to the first surface of the paper by the transfer roll 24 applying a charge having a polarity opposite to that of the toner.

  Thereafter, the sheet is sent to the fixing device 29 by the vacuum conveyance unit 25. The paper sent to the fixing device 29 moves so as to pass between the heating roll 30 and the pressure roll 31 (contact portion), and the paper is applied by the heating action and pressure action applied by the rolls 30 and 31. A toner image is fixed on the first side of the sheet. Next, the paper sent out from the fixing device 29 is sent from the transport roll 11 to the discharge roll 12 along the second paper transport path R2, and then discharged to the paper discharge storage portion (not shown) by the discharge roll 12. Is done. The above operation is applied in single-sided image forming processing for forming an image on one side of a sheet.

  In the double-sided image forming process for forming images on both sides of a sheet, the sheet conveyed by the conveying roll 11 is guided from the second sheet conveying path R2 to the third sheet conveying path R3 by a conveyance switching member (not shown). And fed into the transport roll 13. Next, the sheet is sent to the reverse roll 14 by the transport roll 13 and further sent to the reverse roll 15 by the normal rotation of the reverse roll 14. Next, the sheet is taken into the fourth sheet conveyance path R <b> 4 by the forward rotation of the reverse roll 15. When the trailing edge of the sheet passes the branch position to the fifth sheet conveyance path R5, the reversing roll 15 stops rotating in a state where the sheet is sandwiched, and then starts reverse rotation. Thus, the sheet is fed from the fourth sheet transport path R4 to the fifth sheet transport path R5 according to the reverse rotation of the reversing roll 15.

  Thereafter, the sheet is conveyed from the upstream side to the downstream side along the fifth sheet conveyance path R5 according to the rotation of the plurality of conveyance rolls 16 to 19 provided in the fifth sheet conveyance path R5. Then, at the most downstream portion of the fifth paper transport path R5, the paper is transported by the transport roll 19 so as to merge from the terminal end of the fifth paper transport path R5 to the start end of the second paper transport path R2. . As a result, the sheet is again fed into the pre-registration roll 9 on the second sheet conveyance path R2. Thereafter, an image is formed (transferred and fixed) on the second surface of the sheet in the same procedure as described above. The paper on which the image formation on the second surface has been completed in this manner is sent from the transport roll 11 to the discharge roll 12 along the second paper transport path R2, and then the paper discharge accommodating portion (not shown) by the discharge roll 12. To be discharged.

  When the paper on which image formation on the first surface or the second surface has been completed is reversed and discharged, the paper transported by the discharge roll 11 is transported to the second paper by a transport switching member (not shown). The paper is guided from the path R2 to the third paper transport path R3 and sent to the transport roll 13. Next, the paper is sent to the reverse roll 14 by the transport roll 13, and further sent downstream by the reverse roll 14 in the paper transport direction. When the trailing edge of the sheet passes through the branch position to the sixth sheet conveyance path R6, the reversing roll 14 stops rotating with the sheet sandwiched therebetween, and then starts reverse rotation. As a result, the paper is fed from the third paper transport path R3 to the sixth paper transport path R6 according to the reverse rotation of the reversing roll 14. Next, the sheet is fed from the sixth sheet conveyance path R6 to the discharge roll 12 so as to join the second sheet conveyance path R2, and then discharged to a sheet discharge container (not shown) by the discharge roll 12. The

  2 and 4 are perspective views showing a main part of the sheet conveying apparatus according to the embodiment of the present invention. The paper transport guide member 35 is a long member provided across the width direction of the paper transport path, and as shown in FIG. 2, a guide portion 38, a stopper portion 39, a side plate portion 40, and a support plate. The shaft 41 is integrally provided. The guide portion 38 defines a second paper transport path R2 with the paper transport guide member 37, and is formed in a substantially rectangular shape in cross section to guide the traveling direction of the paper. The stopper portion 39 is provided at one end portion or both end portions in the longitudinal direction of the guide portion 38 so as not to interfere (collision) with the paper conveyed along the paper conveyance path. The stopper portion 39 defines a closed position of the paper transport guide member 35 by being abutted against a fixing portion (not shown).

  The side plate portions 40 are provided at both ends in the longitudinal direction of the guide portion 38. The support shaft 41 is fitted and fixed to the side plate portion 40 by, for example, press-fitting or bonding. The support shaft 41 is rotatably supported by the bracket 42 using a bearing member. The support shaft 41 is for opening and closing the paper transport guide member 35 with the support shaft 41 as a rotation axis. The opening / closing operation of the paper transport guide member 35 is performed in a direction of widening or narrowing the gap of the paper transport path formed between the paper transport guide member 35 and the paper transport guide member 37 facing the paper transport guide member 35. That is, when the paper conveyance guide member 35 is rotated in one direction (hereinafter referred to as “opening direction”) with the support shaft 41 as the rotation axis, a gap in the paper conveyance path formed between the paper conveyance guide member 37 and the paper conveyance guide member 37. When the sheet conveyance guide member 35 is rotated in the other direction (hereinafter referred to as “closing direction”), the gap of the sheet conveyance path formed between the sheet conveyance guide member 37 and the sheet conveyance guide member 37 is relatively increased. It narrows. Here, the operation of rotating the paper transport guide member 35 in the opening direction is defined as “opening operation”, and the operation of rotating the paper transport guide member 35 in the closing direction is defined as “closing operation”. In this case, the terminal position when the sheet conveyance guide member 35 is closed is the closing position defined by the stopper portion 39.

  As shown in FIG. 5, for example, one end of a tension coil spring 43, which is one form of an elastic member, is hooked on the side plate portion 40 of the paper transport guide member 35 as an urging member. The other end of the tension coil spring 43 is hooked on a fixed (non-moving) device frame (not shown). The tension coil spring 43 urges the paper transport guide member 35 in the closing direction with the support shaft 41 as the center of rotation. For this reason, the stopper part 39 receives the urging force of the tension coil spring 43 and is abutted against a fixing part (not shown).

  A lock lever 44 is attached to the outer end of the support shaft 41. The lock lever 44 is fitted and fixed to the support shaft 41 by, for example, press fitting, adhesion, or the like. For this reason, when the paper transport guide member 35 opens and closes with the support shaft 41 as the rotation axis, the lock lever 44 rotates integrally with the support shaft 41 in conjunction with this.

  A lock cam 45 is provided in the vicinity of the lock lever 44. The lock lever 44 and the lock cam 45 are provided as restricting means for restricting the opening operation of the sheet conveyance guide member 35. The lock cam 45 is fitted and fixed to one end of the support shaft 46 by press-fitting, bonding or the like. The lock cam 45 is formed in a substantially sector shape when viewed from the central axis direction of the support shaft 46. The support shaft 46 is rotatably supported by a bracket (not shown) using a bearing member. A gear 47 is attached to the other end of the support shaft 46. A sensor detection piece 48 is attached on the axis of the support shaft 46. The gear 47 and the sensor detection piece 48 rotate integrally with the support shaft 46. The sensor detection piece 48 is formed in a substantially sector shape when viewed from the central axis direction of the support shaft 46.

  The home position detection sensor S3 (see FIG. 3) is a sensor for detecting the home position that is the rotation reference position of the lock cam 45 in the rotation direction of the lock cam 45 about the support shaft 46. The home position detection sensor S3 is configured by using, for example, a transmissive photosensor in which a light emitting element and a light receiving element are arranged in a facing state on a common optical axis. The optical axis of the home position detection sensor S3 is configured to be blocked by the sensor detection piece 48 described above. When the sensor detection piece 48 actually blocks the optical axis of the home position detection sensor S3, the on / off state of the home position detection sensor S3 changes.

  The gear 47 meshes with a drive gear 51 that is fitted and fixed to the output shaft (rotary shaft) of the drive motor 50. The drive motor 50 has a function of rotating in both directions (forward / reverse rotation), and is configured using, for example, a pulse motor. The drive motor 50 is attached to a bracket 49 that is fixed to an apparatus main body frame (not shown) using screws or the like.

  FIG. 6 is a schematic diagram showing a configuration example of a power transmission mechanism using the drive motor 50 as a drive source. As shown in the figure, a one-way clutch 52 is integrally incorporated in the gear 47, and the one-way clutch 52 is fitted and fixed to the support shaft 46. The one-way clutch 52 transmits rotational driving force only in one direction. For this reason, the one-way clutch 52 transmits the rotational driving force to the support shaft 46 when the gear 47 rotates in one direction (hereinafter also referred to as “power transmission direction”). When rotating in the “spinning direction”), it rotates idly and the transmission of rotational driving force is cut off.

  An intermediate gear 53 meshes with the drive gear 51 on the side opposite to the gear 47. A gear 54 meshes with the intermediate gear 53. A one-way clutch 55 is integrally incorporated in the gear 54, and the one-way clutch 55 is fitted and fixed to a support shaft 56. Similar to the one-way clutch 52, the one-way clutch 55 transmits a rotational driving force only in one direction. For this reason, the one-way clutch 55 transmits the rotational driving force to the support shaft 56 when the gear 54 rotates in one direction (hereinafter also referred to as “power transmission direction”). When rotating in the “spinning direction”), it rotates idly and the transmission of rotational driving force is cut off. The support shaft 56 is rotatably supported using a bearing member. A gear 57 is fitted and fixed to the end of the support shaft 56 so as to be coaxial with the gear 54 and the one-way clutch 55. The gear 57 is engaged with the gear 58.

  The gear 58 is fitted and fixed to the end of the rotary drive shaft 59. The rotation drive shaft 59 is rotatably supported by a bearing member. A manual feed paper drive roll 60 is attached to the rotary drive shaft 59. The drive roll 60 rotates integrally with the gear 58 and the rotary drive shaft 59. A pinch roll 61 is in contact with the drive roll 60 at a predetermined pressure. The drive roll 60 and the pinch roll 61 convey the paper toward the registration roll 10 by sandwiching and rotating the manually fed paper between the contact portions (nip portions).

  Here, the intermediate gear 53, the gear 54, the one-way clutch 55, the support shaft 56, the gear 57 and the gear 58 receive the rotational driving force of the driving motor 50 from the driving gear 51, and receive the rotational driving force from the drive roll 60 and the pinch. A first power transmission mechanism for transmitting to the roll 61 is configured. The support shaft 46, gear 47, drive gear 51, and one-way clutch 52 receive a second driving force transmission mechanism that receives the rotational driving force of the driving motor 50 from the driving gear 51 and transmits the rotational driving force to the lock cam 45. It constitutes.

  In the power transmission mechanism configured as described above, when the drive gear 51 is rotated by driving the drive motor 50, the gear 47 and the intermediate gear 53 are rotated simultaneously with the rotation of the drive gear 51. In this case, if the rotation direction of the gear 47 is the same direction as the power transmission direction of the one-way clutch 52, the support shaft 46 rotates together with the gear 47, and the rotation direction of the gear 47 is the same direction as the idling direction of the one-way clutch 52. Then, even if the gear 47 rotates, the support shaft 46 does not rotate.

  Further, when the intermediate gear 53 rotates, the gear 54 rotates according to the rotation of the intermediate gear 53. In this case, if the rotation direction of the gear 54 is the same direction as the power transmission direction of the one-way clutch 55, the support shaft 56 rotates together with the gear 54, and the rotation direction of the gear 54 is the same direction as the idling direction of the one-way clutch 55. If so, the support shaft 56 does not rotate even when the gear 54 rotates.

  Here, when viewed from the direction F in FIG. 6, the motor rotation direction when the drive gear 51 of the drive motor 50 rotates counterclockwise is defined as “forward rotation”, and the drive gear 51 of the drive motor 50 rotates clockwise. The direction of rotation of the motor when it is rotated is defined as “reverse rotation”. In such a case, when the drive gear 51 of the drive motor 50 rotates forward, the rotational driving force is simultaneously transmitted to the gear 47 and the intermediate gear 53 via the drive gear 51. Among these, the rotational driving force transmitted to the gear 47 is not transmitted to the support shaft 46 due to the idling of the one-way clutch 52. The rotational driving force transmitted to the intermediate gear 53 is transmitted to the support shaft 56 via the gear 54 and the one-way clutch 55, and further transmitted to the rotational driving shaft 59 and the drive roll 60 via the gear 57 and gear 58. The For this reason, when the drive gear 51 of the drive motor 50 is rotated forward, the rotation of the lock cam 45 is stopped, the drive roll 60 rotates together with the rotary drive shaft 59, and the drive roll 60 rotates. Therefore, the pinch roll 61 rotates.

  On the other hand, when the drive gear 51 of the drive motor 50 rotates in the reverse direction, the rotational driving force is transmitted to the gear 47 and the intermediate gear 53 via the drive gear 51. Among these, the rotational driving force transmitted to the intermediate gear 53 is not transmitted to the support shaft 56 due to the idling of the one-way clutch 55. Further, the rotational driving force transmitted to the gear 47 is transmitted to the support shaft 46 and the lock cam 45 via the one-way clutch 52. For this reason, when the drive gear 51 of the drive motor 50 is reversely rotated, the lock cam 45 and the sensor detection piece 48 rotate together with the support shaft 46 while the rotation of the drive roll 60 and the pinch roll 61 is stopped. become. Therefore, the first power transmission mechanism selects the rotational driving force as the manual feeding member (60, 61) when the driving motor 50 as a driving source is rotationally driven in the first direction. The second power transmission mechanism selectively transmits the rotational driving force to the lock cam 45 when the drive motor 50 is rotationally driven in the second direction.

  FIG. 7 is a block diagram showing a schematic configuration of a control system of the image forming apparatus according to the embodiment of the present invention. The main control unit 60 controls the overall processing operation of the image forming apparatus. The main control unit 60 is largely configured to include an image formation control unit 61 and a paper conveyance control unit 62. The image forming control unit 61 mainly controls the image forming operation by the image forming unit. The paper transport control unit 62 mainly controls the paper transport operation by the paper transport device.

  In addition to the first paper detection sensor S 1, the second paper detection sensor S 2, the home position detection sensor S 3, and the drive motor 50 described above, a pre-registration motor 63 and a registration motor 64 are connected to the paper transport control unit 62. ing.

  When the paper conveyance control unit 62 rotates the lock cam 45 and the sensor detection piece 48 integrally with the support shaft 46 by driving the drive motor 50, the on / off state of the home position detection sensor S3 changes from the on state to the off state, for example. The position when changed is recognized (detected) as the rotation reference position of the lock cam 45.

  The pre-registration motor 63 is a drive source for rotating the pre-registration roll 9. The registration motor 64 is a drive source for rotating the registration roll 10. In FIG. 7, among the components of the sheet conveying apparatus, particularly, components for controlling the conveyance of the sheet on the second sheet conveying path R2 from the pre-registration roll 9 to the registration roll 10 are extracted. Display of other components is omitted.

  FIG. 8 is a flowchart illustrating an example of a processing procedure related to sheet conveyance control. Here, a processing procedure applied when a sheet of paper to be image-formed is sent from the pre-registration roll 9 to the image recording position P via the registration roll 10 will be described.

  First, the sheet conveyance control unit 62 uses the stopper unit 39 as shown in FIG. 5A at a stage before the leading edge of the sheet conveyed by the pre-registration roll 9 passes the detection position of the first sheet detection sensor S1. A state in which the sheet conveyance guide member 35 is disposed at a prescribed closed position and the sheet conveyance guide member 35 is fixed at the closed position by bringing the lock cam 45 into contact with or close to the lock lever 44 as shown in FIG. 9A. Thus, the opening operation of the sheet conveyance guide member 35 is regulated. A state in which the opening operation of the sheet conveyance guide member 35 is regulated using the lock cam 45 is described as a “locked state”.

  Under such a locked state, the sheet conveyance control unit 62 confirms whether or not the second sheet detection sensor S2 is turned on (step ST1). Then, when the leading edge of the sheet passes the detection position of the second sheet detection sensor S2 and the second sheet detection sensor S2 is turned on, the sheet conveyance control unit 62 performs a predetermined time from the timing when the second sheet detection sensor S2 is turned on. After T1, the drive motor 50 is driven to reversely rotate the drive gear 51, thereby releasing the locked state (regulation of the opening operation of the paper conveyance guide member 35) by the lock cam 45 (step ST2).

  When the lock state is released by driving the drive motor 50, the lock cam 45 is rotated halfway (180 ° rotation) together with the support shaft 46 as shown in FIG. The lock cam 45 is separated from the lever 44. The timing for releasing the locked state may be before the sheet starts to be bent in a loop shape by abutting against the registration roll 10. Therefore, the locked state may be released at the same time as the second sheet detection sensor S2 is turned on, or the locked state is within a period from when the second sheet detection sensor S2 is turned on until the leading edge of the sheet hits the registration roll 10. May be released.

  Next, the sheet conveyance control unit 62 stops driving the preregistration motor 63 after a predetermined time T2 (where T2> T1) after the second sheet detection sensor S2 is turned on, so The feeding is stopped (step ST3). At this time, in the inclination correction unit 20, the paper is bent in a loop shape with the leading edge of the paper hitting the registration roll 10. The amount of deflection (loop amount) of the paper is determined by the time from when the leading edge of the paper hits the registration roll 10 until the rotation of the pre-registration roll 9 stops. For this reason, the paper conveyance control unit 62 individually controls the amount of paper deflection for each paper type by adjusting the predetermined time T2 according to the paper type.

  Further, in the process in which the paper is bent in a loop shape, the paper conveyance guide member 35 is pushed by the paper loop and rotates in the opening direction against the urging force of the tension coil spring 43 as shown in FIG. . Therefore, the urging force of the tension coil spring 43 is applied to the sheet bent in a loop shape, and the leading end of the sheet is pressed against the contact portion (nip portion) of the resist roll 10 by receiving the urging force. Further, a gap corresponding to the amount of deflection of the paper is formed in the paper transport path between the paper transport guide member 35 and the paper transport guide member 37.

  Thereafter, the paper transport control unit 62 simultaneously drives the pre-registration motor 63 and the registration motor 64 at a predetermined timing, thereby rotating the pre-registration roll 9 and the registration roll 10 together to start feeding the paper to the image recording position P. (Step ST4).

  When the registration roll 10 starts feeding the paper, the inclination correction unit 20 gradually reduces the paper loop (deflection). For this reason, the paper transport guide member 35 gradually rotates in the closing direction according to the urging force of the tension coil spring 43, and returns to the closed position when the deflection of the paper is eliminated.

  Next, the sheet conveyance control unit 62 confirms whether or not the first sheet detection sensor S1 is turned off (step ST5). When the trailing edge of the sheet passes the detection position of the first sheet detection sensor S1 and the first sheet detection sensor S1 is turned off, the sheet conveyance control unit 62 drives the drive motor 50 again to drive at that stage. The gear 51 is reversely rotated to return to the locked state by the lock cam 45 (step ST6).

  When returning to the locked state by driving the drive motor 50, the lock cam 45 is moved together with the support shaft 46 by the reverse rotation of the drive gear 51 so that the state shown in FIG. 9B is changed to the state shown in FIG. 9A. Make a half turn. As a result, the lock cam 45 returns to the state in contact with or close to the lock lever 44.

  Thereafter, the sheet conveyance control unit 62 confirms whether or not the second sheet detection sensor S2 is turned off (step ST7). When the trailing edge of the sheet passes the detection position of the second sheet detection sensor S2 and the second sheet detection sensor S2 is turned off, the sheet conveyance control unit 62 performs a predetermined process after the second sheet detection sensor S2 is turned off. After time T3 (the time required for the trailing edge of the paper to pass through the registration roll 10), the driving of the registration motor 64 is stopped to stop the rotation of the registration roll 10 (step ST8).

  By controlling the sheet conveyance in such a procedure, when the leading edge of the sheet passes through the sheet conveyance guide member 35, the opening operation of the sheet conveyance guide member 35 is restricted by the lock cam 45. Even when a strong paper (such as thick paper) is transported, the paper transport guide member 35 is not rotated in the opening direction by being pushed by the paper. For this reason, the gap of the second paper transport path R2 is maintained in a narrow state between the paper transport guide member 35 and the paper transport guide member 37. Therefore, the leading edge of the sheet conveyed by the pre-registration roll 9 can be reliably guided to the registration roll 10 along the guide portion 38 of the sheet conveyance guide member 35.

  On the other hand, when the leading edge of the paper hits the registration roll 10, the paper starts to be bent in a loop as the paper is fed by the pre-registration roll 9. At this stage, since the locked state by the lock cam 45 is released as shown in FIG. 9B, the lock lever 44 can rotate integrally with the support shaft 41. Further, since the paper transport guide member 35 rotates integrally with the support shaft 41, the paper transport guide member 35 can rotate (open operation) against the urging force of the tension coil spring 43.

  For this reason, when the paper is bent in a loop shape as shown in FIG. 5B, the paper transport guide member 35 rotates in the opening direction as it is pushed out by the loop portion of the paper, and the lock lever 44 is also interlocked with this. It rotates as shown in FIG. In this case, the leading edge of the paper is simultaneously pressed by the reaction force accompanying the loop formation and the urging force of the tension coil spring 43 acting on the paper transport guide member 35 and pressed against the contact portion (nip portion) of the registration roll 10. Become. Therefore, the leading edge of the paper can be brought into contact with the registration roll 10 with a sufficient driving force required for inclination correction.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus to which the present invention is applied. FIG. 3 is a perspective view (No. 1) illustrating a main part of the sheet conveying device according to the embodiment of the invention. It is a perspective view (the 2) which shows the principal part of the paper conveying apparatus which concerns on embodiment of this invention. FIG. 6 is a perspective view (No. 3) illustrating a main part of the sheet conveying device according to the embodiment of the present invention. It is a figure explaining the structure and operation | movement of an inclination correction part. It is a schematic diagram which shows the structural example of a power transmission mechanism. 1 is a block diagram illustrating a schematic configuration of a control system of an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating an example of a processing procedure related to paper conveyance control. It is a figure explaining the structure and operation | movement of a control means.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 9 ... Pre-registration roll, 10 ... Registration roll, 20 ... Tilt correction part, 21 ... Image transfer part, 35 ... Paper conveyance guide member, 43 ... Tension coil spring, 44 ... Lock lever, 45 ... Lock cam, 47, 54, 57, 58 ... Gear, 50 ... Drive motor, 51 ... Drive gear, 52,55 ... One-way clutch, 53 ... Intermediate gear, 60 ... Drive roll, 61 ... Pinch roll, 62 ... Paper transport control unit, 63 ... Pre-registration motor, 64 ... Registration motor , P: image recording position, S1: first paper detection sensor, S2: second paper detection sensor

Claims (3)

Paper transport means for transporting paper along the paper transport path;
A reference member against which the leading edge of the paper abuts on the paper conveyance path;
Provided on the upstream side of the reference member in the paper conveyance direction and in a portion where the paper is bent by abutting against the reference member, and operates in an opening direction that widens the gap of the paper conveyance path and a closing direction that narrows the gap. A paper transport guide member;
Biasing means for biasing the paper transport guide member in the closing direction;
A restricting means for restricting an opening operation of the paper transport guide member in a state where the paper transport guide member is fixed at a closed position;
Before the leading edge of the paper passes through the paper conveyance guide member, the opening of the paper conveyance guide member is regulated by the regulating means, and after the leading edge of the paper passes through the paper conveyance guide member, the regulation is performed. And a control means for controlling to release the restriction of the opening operation by the means. In the paper conveyance device according to claim 1,
A drive source that rotates in both directions;
A first power transmission mechanism that selectively transmits the rotational driving force to a manual sheet feeding member when the driving source is rotationally driven in a first direction;
And a second power transmission mechanism that selectively transmits the rotational driving force to the restricting means when the driving source is rotationally driven in the second direction. Paper transport means for transporting paper along the paper transport path;
An image forming unit that forms an image on a sheet conveyed by the sheet conveying unit and records an image on the sheet at an image recording position provided in the middle of the sheet conveying path;
A reference member that is provided upstream of the image recording position in the paper conveyance direction and on which the leading edge of the paper abuts on the paper conveyance path;
Provided on the upstream side of the reference member in the paper conveyance direction and in a portion where the paper is bent by abutting against the reference member, and operates in an opening direction that widens the gap of the paper conveyance path and a closing direction that narrows the gap. A paper transport guide member;
Biasing means for biasing the paper transport guide member in the closing direction;
A restricting means for restricting an opening operation of the paper transport guide member in a state where the paper transport guide member is fixed at a closed position;
Before the leading edge of the paper passes through the paper conveyance guide member, the opening of the paper conveyance guide member is regulated by the regulating means, and after the leading edge of the paper passes through the paper conveyance guide member, the regulation is performed. An image forming apparatus comprising: a control unit that controls to release the restriction of the opening operation by the unit.

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