Image forming device

Abstract

To provide an image forming device provided with first and second discharge routes and capable of reducing drive noise.SOLUTION: In an image forming device 1, a sheet SH having passed through an image forming unit 3 is guided through a second discharge route PD2 to a post-processing unit 4, and discharged. A second conveyance roller pair 29 conveys the sheet SH on the second discharge route PD2. A drive force transmission mechanism 500 transmits a drive force from one driver source M1 to first and second conveyance roller pairs 28 and 29. The drive force transmission mechanism 500 includes a switching part 500C. When executing a first discharge operation for discharging the sheet SH from a first discharge route PD1, the switching part 500C transmits the driving force to the first conveyance roller pair 28 while cutting off transmission of the drive force to the second conveyance roller pair 29. The switching part 500C transmits the drive force to at least the second conveyance roller pair 29 when executing a second discharge operation for discharging the sheet SH from the second discharge route PD2.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] An example of a conventional image forming apparatus is disclosed in Patent Document 1. This image forming apparatus includes an image forming section, a first transport path, a second transport path, a first discharge roller, and a second discharge roller.

[0003] The first conveying path discharges the sheet that has passed through the image forming unit, and the second conveying path guides the sheet that has passed through the image forming unit to a cutter and discharges the sheet that has passed through the cutter.

[0004] The first discharge roller and the second discharge roller are roller pairs each having a drive roller and a driven roller. The first discharge roller conveys the sheet along the first transport path. The second discharge roller conveys the sheet along the second transport path.

[0005] This image forming apparatus also includes a conveying motor (shown in Fig. 6) and a driving force transmission mechanism (not shown). There is one conveying motor that generates driving force. The driving force transmission mechanism transmits the driving force from the conveying motor to the first discharge roller and the second discharge roller. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2024-18327 Summary of the Invention [Problem to be solved by the invention]

[0007] However, image forming apparatuses are required to reduce driving noise. In this regard, in the conventional image forming apparatuses described above, it is difficult to reduce driving noise because one transport motor always drives the first and second discharge rollers when transporting a sheet along the first transport path and when transporting a sheet along the second transport path.

[0008] The present invention has been made in view of the above-described conventional circumstances, and has an object to provide an image forming apparatus that is configured to include a first discharge path and a second discharge path and that can reduce driving noise. [Means for solving the problem]

[0009] The image forming apparatus of the present invention includes: an image forming unit that forms an image on a sheet; a first discharge path for discharging the sheet that has passed through the image forming unit; a second discharge path that guides the sheet that has passed through the image forming unit to a post-processing unit that performs predetermined post-processing, and discharges the sheet that has passed through the post-processing unit; a first conveying roller pair that conveys the sheet along the first discharge path; a second conveying roller pair that conveys the sheet along the second discharge path; One driving source that generates a driving force; a driving force transmission mechanism that transmits the driving force from the driving source to the first conveying roller pair and the second conveying roller pair; An image forming apparatus comprising: The driving force transmission mechanism is characterized in that it has a switching unit that transmits the driving force to the first conveying roller pair when performing a first discharge operation to discharge a sheet from the first discharge path, and cuts off the transmission of the driving force to the second conveying roller pair, and that transmits the driving force to at least the second conveying roller pair when performing a second discharge operation to discharge a sheet from the second discharge path.

[0010] In the image forming apparatus of the present invention, the first discharge operation, in which a sheet that has passed through the image forming unit is discharged as is, is performed more frequently than the second discharge operation, in which a sheet that has passed through the image forming unit is subjected to post-processing before being discharged.

[0011] The switching unit blocks the transmission of the driving force to the second conveying roller pair that does not contribute to conveying the sheet during the first discharge operation, which is frequently performed, and can eliminate the driving noise associated with the second conveying roller pair.

[0012] In addition, during the second discharge operation, the first conveying roller pair, which does not contribute to the conveyance of the sheet, may be driven together with the second conveying roller pair, but since the second discharge operation is performed infrequently, the driving noise associated with the first conveying roller pair is unlikely to be a problem.

[0013] Therefore, in the image forming apparatus of the present invention, when the image forming apparatus is configured to include the first and second discharge paths, it is possible to reduce drive noise. Also, the image forming apparatus can suppress wear of the second conveying roller pair, thereby achieving a longer life for the second conveying roller pair. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of an image forming apparatus according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the image forming apparatus according to the first embodiment. [Figure 3] FIG. 3 is a perspective view showing a unit including the cutter mechanism, the first guide, and the pre-cutting guide. [Figure 4] FIG. 4 is a partial schematic cross-sectional view showing an enlarged essential part of FIG. [Figure 5] FIG. 5 is a schematic partial side view of the image forming apparatus according to the first embodiment, showing the motor and the driving force transmission mechanism. [Figure 6] FIG. 6 is a top view of the motor and the driving force transmission mechanism. [Figure 7] FIG. 7 is a perspective view showing the driving force transmission mechanism with the sheet metal frame removed. [Figure 8]FIG. 8 is a side view showing the driving force transmission mechanism with the metal plate frame and the resin frame removed, and is a diagram illustrating the operation when the motor rotates forward. [Figure 9] FIG. 9 is a side view similar to FIG. 8, illustrating the operation when the motor rotates in the reverse direction. [Figure 10] FIG. 10 is a partial schematic cross-sectional view showing an enlarged essential part of FIG. 2, illustrating the moving distance of the sheet. [Figure 11] FIG. 11 is a side view similar to FIG. 8 of the image forming apparatus according to the second embodiment, illustrating the operation when the motor rotates forward. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, first to third embodiments of the present invention will be described with reference to the drawings.

[0016] Example 1 As shown in Fig. 1, an image forming apparatus 1 of the first embodiment is an example of a specific aspect of the image forming apparatus of the present invention. As shown in Fig. 2, the image forming apparatus 1 includes an image forming unit 3 and a fixing unit 7 that form an image on a sheet SH by an electrophotographic method, and an image reading unit that reads an image of a document. The multifunction device is equipped with a reading unit 35.

[0017] In Fig. 1, the side of the operation panel 37 of the image forming apparatus 1 is the front. The left-right direction of the image forming apparatus 1 is a direction that is perpendicular to the front-rear direction and extends horizontally. The side that is to the left when facing the operation panel 37 is the left side. The directions shown in Fig. 2 and subsequent figures are all displayed in correspondence with the directions shown in Fig. 1.

[0018] <Overall structure> As shown in FIGS. 1 and 2, the image forming apparatus 1 includes a first housing 10, a second housing 30, and a joint cover 50.

[0019] The first housing 10 is a generally box-shaped body. The second housing 30 is a generally box-shaped body with a flat shape whose vertical length is significantly smaller than that of the first housing 10. The second housing 30 is spaced above the first housing 10. The joint cover 50 supports the second housing 30 from below above the first housing 10.

[0020] As shown in FIG. 2, the first housing 10 accommodates a sheet cassette 10C in its lower portion. The sheet cassette 10C supports a stack of sheets SH on which images are to be formed. The sheets SH are paper, transparencies, etc. The first housing 10 accommodates an image forming unit 3 and a fixing unit 7 above the sheet cassette 10C.

[0021] The first housing 10 has an exterior cover 90. The exterior cover 90 forms part of the exterior surface of the rear surface of the first housing 10.

[0022] 1 and 2, the joint cover 50 has a discharge tray 9. The discharge tray 9 is located in the center in the left-right direction on the top surface of the first housing 10. The discharge tray 9 extends horizontally rearward from the front end side of the top surface of the first housing 10, then bends and slopes downward rearward.

[0023] The second housing 30 and the joint cover 50 have a discharge space AD1. The discharge space AD1 is defined between the first housing 10 and the second housing 30.

[0024] The discharge tray 9 defines the lower side of the discharge space AD1. The sheet SH on which an image is formed after passing through the image forming unit 3 and the fixing unit 7 is discharged into the discharge space AD1. The discharge tray 9 supports the sheet SH discharged into the discharge space AD1. In this embodiment, the image forming apparatus 1 is equipped with one discharge tray 9.

[0025] 1, the joint cover 50 has support portions 57L and 57R. The support portion 57L is a portion of the joint cover 50 that is located to the left of the discharge tray 9 and protrudes upward. The support portion 57R is a portion of the joint cover 50 that is located to the right of the discharge tray 9 and protrudes upward.

[0026] The joint cover 50 has inner wall surfaces 58, 59. The inner wall surface 58 is the right side surface of the support portion 57L. The inner wall surface 58 defines the left side of the discharge space AD1. The inner wall surface 59 is the left side surface of the support portion 57R. The inner wall surface 59 defines the right side of the discharge space AD1.

[0027] The support portions 57L and 57R of the joint cover 50 support the second housing 30 at a position above the first housing 10 at their upper ends.

[0028] As shown in Fig. 2, the second housing 30 houses the image reading unit 35. The image reading unit 35 is located above and spaced apart from the discharge tray 9. The image reading unit 35 has a well-known configuration and will not be described briefly, but it reads an image of a document placed on the top surface of the second housing 30 using a reading sensor (not shown). The document is a book, a sheet, etc.

[0029] The second housing 30 also has a document cover 40 whose top surface can be opened and closed, and an automatic document feeder mechanism 45 housed in the document cover 40.

[0030] 1, the document cover 40 has a supply tray 41 and a discharge tray 42 located on the right side thereof. The supply tray 41 is spaced above the discharge tray 42.

[0031] The automatic document feed mechanism 45 has a well-known configuration and will not be described here, but it feeds sheet-like documents supported on a supply tray 41 to a position where they can be read by a reading sensor (not shown) of the image reading unit 35, and then discharges the documents onto a discharge tray 42. The reading sensor (not shown) reads the image of the documents being fed.

[0032] The operation panel 37 protrudes forward from a portion located to the left of the discharge space AD1 on the front end surface of the second housing 30. The operation panel 37 is supported from below by the front end of the support portion 57L of the joint cover 50.

[0033] The operation panel 37 has an operation surface that receives operation inputs by the user's finger and a display unit such as an LCD located below the operation surface. The operation panel 37 displays information indicating the operating status and settings of the image forming apparatus 1, and notifies the user by displaying error messages and the like.

[0034] 2, the image forming unit 3 has a developing device 3A, a photoconductor 5, and a scanner unit 8. The image forming apparatus 1 includes a first feeding roller 21, a first separation roller 22, a separation pad 22A, a conveying roller pair 23, a registration roller pair 24, and a post-fixing conveying roller pair 25, which are housed in a first housing 10 together with the image forming unit 3 and the fixing unit 7.

[0035] A first feeding roller 21, a first separation roller 22, a separation pad 22A, and a conveying roller pair 23 are located in the front of the first housing 10. A post-fixing conveying roller pair 25 is located in the rear of the first housing 10.

[0036] A transport path P1 is provided inside the first housing 10. The transport path P1 starts from the front end of the sheet cassette 10C, makes a U-turn upward, passes through a first feeding roller 21, a first separation roller 22, a separation pad 22A, and a transport roller pair 23, then proceeds rearward in a substantially horizontal direction, passes through a registration roller pair 24, a photosensitive member 5, and a fixing unit 7, and reaches a post-fixing transport roller pair 25.

[0037] The first feeding roller 21 is located at the most upstream end of the conveying path P1. The first separation roller 22 and separation pad 22A are located downstream of the first feeding roller 21 on the conveying path P1. The conveying roller pair 23 is located downstream of the first separation roller 22 and separation pad 22A on the conveying path P1, midway along the portion of the conveying path P1 where it makes an upward U-turn.

[0038] The registration roller pair 24 is located downstream of the transport roller pair 23 on the transport path P1 and upstream of the photosensitive member 5 on the transport path P1, midway along the portion of the transport path P1 that moves substantially horizontally backward.

[0039] The first feeding roller 21 feeds the sheet SH supported by the sheet cassette 10C toward the photosensitive member 5. If there are multiple sheets SH sent to the conveying path P1 by the first feeding roller 21, the first separation roller 22 and separation pad 22A separate the sheets SH one by one. Then, the conveying roller pair 23 and the registration roller pair 24 convey the sheets SH to the photosensitive member 5.

[0040] The developing device 3A has a toner storage chamber 3D that stores toner, and a developing roller 3B to which toner is supplied from the toner storage chamber 3D. The photoreceptor 5 is located behind and below the developing roller 3B and is in contact with the developing roller 3B.

[0041] The photoreceptor 5 is a cylindrical rotating body centered on a rotation axis extending in the left-right direction. A positively charged photosensitive layer is formed on the surface of the photoreceptor 5 in correspondence with positively charged toner. Note that a negatively charged photosensitive layer may also be formed on the surface of the photoreceptor 5, in which case negatively charged toner is used.

[0042] The photosensitive member 5 can come into contact from above with the sheet SH that is transported along the portion of the transport path P1 that moves rearward and approximately horizontally. A transfer roller 5A is located below the photosensitive member 5. The transfer roller 5A faces the photosensitive member 5 from below, with the transport path P1 in between.

[0043] The developing device 3A further includes a charger 3E, which faces the rear of the photosensitive member 5. The charger 3E is a well-known scorotron charger.

[0044] The scanner unit 8 is located above the developing device 3A and the photoconductor 5. The scanner unit 8 has a known configuration including a laser light source, a polygon mirror, an fθ lens, and a reflecting mirror. The scanner unit 8 irradiates the surface of the photoconductor 5 with a laser beam.

[0045] The surface of the photoreceptor 5 is uniformly positively charged by the charger 3E as it rotates, and then exposed to high-speed scanning of a laser beam emitted from the scanner unit 8. As a result, an electrostatic latent image corresponding to the image to be formed on the sheet SH is formed on the surface of the photoreceptor 5.

[0046] Then, the developing roller 3B supplies toner to the photoreceptor 5 in accordance with the electrostatic latent image formed on the surface of the photoreceptor 5. As a result, a toner image is carried on the surface of the photoreceptor 5. The photoreceptor 5 transfers the toner image to the upward surface of the sheet SH that passes through the nip position between the photoreceptor 5 and the transfer roller 5A.

[0047] The fixing unit 7 is located behind the photosensitive member 5 and in front of the post-fixing conveying roller pair 25. The fixing unit 7 has a heating member 7A located above the conveying path P1, and a pressure roller 7B facing the heating member 7A from below across the conveying path P1.

[0048] The heating member 7A includes an endless belt, a guide member that supports the endless belt from its inner periphery so that it can circulate, and a heater that heats the endless belt from its inner periphery. The heating member 7A and pressure roller 7B nip the sheet SH at the fixing nip 7N. The heating member 7A may be configured as a heating roller having a heater such as a halogen heater, or may be configured as a heater, a nip plate that receives radiant heat from the heater, and a heating belt that rotates around the nip plate.

[0049] The fixing unit 7 heats and presses the sheet SH onto which the toner image has been transferred using a heating member 7A and a pressure roller 7B, thereby thermally fixing the toner image onto the sheet SH. A post-fixing conveying roller pair 25 conveys the sheet SH that has passed through the fixing unit 7 upward and backward.

[0050] The image forming apparatus 1 includes a control unit C1, a pre-registration sheet sensor S1, a post-registration sheet sensor S2, and a post-fixing sheet sensor S3.

[0051] The first housing 10 houses a control unit C1. The control unit C1 is an electronic circuit unit including a CPU, an interface circuit, and a storage unit (not shown). The control unit C1 performs overall control over each unit of the image forming apparatus 1.

[0052] The control unit C1 is electrically connected to the pre-registration sheet sensor S1, the post-registration sheet sensor S2, and the post-fixing sheet sensor S3.

[0053] The pre-registration sheet sensor S1 is located immediately before the pair of registration rollers 24 on the conveying path P1, and detects the passage of the sheet SH and transmits the detection result to the control unit C1. Based on the detection result of the pre-registration sheet sensor S1, the control unit C1 performs control such as correcting skew of the sheet SH that reaches the pair of registration rollers 24.

[0054] The post-registration sheet sensor S2 is located immediately after the pair of registration rollers 24 on the conveying path P1, and detects the passage of the sheet SH and transmits the detection result to the control unit C1. The control unit C1 controls the timing of the image forming operation by the image forming unit 3 and the fixing unit 7 based on the detection result of the post-registration sheet sensor S2.

[0055] The post-fixing sheet sensor S3 is located between the fixing unit 7 and the post-fixing conveying roller pair 25 on the conveying path P1, detects the passage of the sheet SH, and transmits the detection result to the control unit C1. Based on the detection result of the post-fixing sheet sensor S3, the control unit C1 controls the timing of a plurality of operations that are performed until the sheet SH that has passed through the fixing unit 7 is discharged onto the discharge tray 9.

[0056] The pre-registration sheet sensor S1, the post-registration sheet sensor S2, and the post-fixing sheet sensor S3 may be a sensor having an actuator that swings when the sheet SH comes into contact with it, or a light reflection type sensor.

[0057] The image forming apparatus 1 includes a flapper 26. The flapper 26 is located above the post-fixing conveying roller pair 25 and is connected to a solenoid (not shown). The control unit C1 controls the solenoid (not shown) to swing the flapper 26 between the position indicated by the solid line in FIG. 2 and the position indicated by the two-dot chain line in FIG. 2.

[0058] The image forming apparatus 1 includes a first discharge path PD1 and a second discharge path PD2. The upstream ends of the first discharge path PD1 and the second discharge path PD2 are connected to the downstream end of the transport path P1.

[0059] The first discharge path PD1 is a discharge path that is effective when the flapper 26 is in the position shown by the two-dot chain line in Fig. 2. The second discharge path PD2 is a discharge path that is effective when the flapper 26 is in the position shown by the solid line in Fig. 2.

[0060] The first discharge path PD1 is a path along which the sheet SH that has passed through the image forming unit 3 and the fixing unit 7 is guided along the flapper 26 positioned as indicated by the two-dot chain line in FIG. 2 and discharged to the discharge space AD1.

[0061] The second discharge path PD2 is a path that guides the sheet SH that has passed through the image forming unit 3 and the fixing unit 7 upward along the flapper 26 located at the position shown by the solid line in Figure 2, then moves forward in an approximately horizontal direction to guide it to the cutter mechanism 4 described below, and discharges the sheet SH that has passed through the cutter mechanism 4 into the discharge space AD1.

[0062] The direction in which the sheet SH is conveyed substantially horizontally forward along the second discharge path PD2 is defined as a discharge direction DE1. The first discharge path PD1 discharges the sheet SH into the discharge space AD1 at a position lower than the second discharge path PD2 and upstream of the second discharge path PD2 in the discharge direction DE1.

[0063] The image forming apparatus 1 includes a first conveying roller pair 28 disposed at the most downstream end of the first discharge path PD1.

[0064] The first conveying roller pair 28 is located above the upstream end 9U of the discharge tray 9 in the discharge direction DE1. The first conveying roller pair 28 has a drive roller 28A and a driven roller 28B. The driven roller 28B is located below the drive roller 28A and faces the drive roller 28A.

[0065] The first conveying roller pair 28 conveys the sheet SH along the first discharge path PD1. The first conveying roller pair 28 discharges the sheet SH, which has passed through the image forming unit 3 and the fixing unit 7 but has not passed through the cutter mechanism 4, onto the discharge tray 9.

[0066] The image forming apparatus 1 includes a pre-cutting cover 80 and a third conveying roller pair 70 disposed on the second discharge path PD2. The pre-cutting cover 80 and the third conveying roller pair 70 are located above the flapper 26 in the vertical direction.

[0067] The third conveying roller pair 70 has a drive roller 70A and a driven roller 70B. The pre-cutting cover 80 rotatably supports the drive roller 70A and the driven roller 70B. The driven roller 70B is located below the drive roller 70A and faces the drive roller 70A. The third conveying roller pair 70 conveys the sheet SH in the discharge direction DE1 along the second discharge path PD2.

[0068] As shown in FIGS. 2 to 4, the image forming apparatus 1 includes a pre-cutting guide 300, a cutter mechanism 4, a first guide 100, a second guide 200, a sheet sensor S4, and a second conveying roller pair 29.

[0069] The cutter mechanism 4 is an example of a "post-processing section" of the present invention. The cutter mechanism 4 performs a cutting process as a predetermined post-processing, cutting the sheet SH in the width direction perpendicular to the discharge direction DE1, that is, in the left-right direction.

[0070] As shown in Figure 2, the pre-cutting guide 300, cutter mechanism 4, first guide 100, second guide 200, sheet sensor S4 and second conveying roller pair 29 are arranged downstream of the pre-cutting cover 80 and third conveying roller pair 70 in the discharge direction DE1 on the second discharge path PD2.

[0071] The second conveying roller pair 29 is located below the image reading unit 35 and above the first conveying roller pair 28. The second conveying roller pair 29 is located downstream of the first conveying roller pair 28 in the discharge direction DE1.

[0072] The second conveying roller pair 29 is located on the opposite side of the cutter mechanism 4 from the third conveying roller pair 70. Specifically, the second conveying roller pair 29 is located downstream of the cutter mechanism 4 in the discharge direction DE1. The third conveying roller pair 70 is located upstream of the cutter mechanism 4 in the discharge direction DE1. The second conveying roller pair 29 is located above the middle part of the downwardly sloping portion of the discharge tray 9 in the front-to-rear direction.

[0073] The second conveying roller pair 29 has a drive roller 29A and a driven roller 29B. The driven roller 29B is located below the drive roller 29A and faces the drive roller 29A.

[0074] The second conveying roller pair 29 conveys the sheet SH along the second discharge path PD2. The second conveying roller pair 29 passes through the image forming unit 3 and the fixing unit 7, and discharges the sheet SH (SH1) cut in half by the cutter mechanism 4 onto the discharge tray 9.

[0075] The image forming apparatus 1 in this embodiment cuts the sheet SH so that the length of the side along the discharge direction DE1 is halved. The discharge tray 9 supports the sheet SH (SH1) that is cut by the cutter mechanism 4 and then discharged.

[0076] That is, the discharge tray 9 supports the sheet SH discharged from the first discharge path PD1 and the second discharge path PD2. The first conveying roller pair 28 and the second conveying roller pair 29 discharge the sheet SH toward the discharge tray 9 in the same direction.

[0077] 5, the image forming apparatus 1 includes a motor M1 that generates a driving force for driving the first conveying roller pair 28, the second conveying roller pair 29, and the third conveying roller pair 70. The motor M1 is an example of the "driving source" of the present invention. In this embodiment, the motor M1 is a stepping motor.

[0078] The image forming apparatus 1 also includes a driving force transmission mechanism 500 that transmits driving force from the motor M1 to the first conveying roller pair 28, the second conveying roller pair 29, and the third conveying roller pair 70. The configuration of the driving force transmission mechanism 500 will be described in detail later.

[0079] The motor M1 and the driving force transmission mechanism 500 are disposed within the support portion 57L of the joint cover 50.

[0080] <Pre-cutting guide, cutter mechanism, first guide, second guide, sheet sensor, and second conveying roller pair> 3 and 4, the pre-cutting guide 300, the cutter mechanism 4, and the first guide 100 are fastened together to form a unit. As shown in Fig. 2, the pre-cutting guide 300, the cutter mechanism 4, and the first guide 100 are assembled as a unit to the joint cover 50 and fixed to the joint cover 50.

[0081] As shown in FIG. 4, the pre-cutting guide 300 is provided downstream of the third conveying roller pair 70 in the discharge direction DE1 and upstream of a fixed blade 411 and a moving blade 412 (described later) of the cutter mechanism 4 in the discharge direction DE1.

[0082] The pre-cutting guide 300 has guide surfaces 301 and 302 that guide the sheet SH passing through the cutter mechanism 4. The guide surface 301 faces the guide surface 302 from above. The pre-cutting guide 300 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0083] The sheet SH conveyed by the third conveying roller pair 70 toward the cutter mechanism 4 passes between the guide surface 301 and the guide surface 302 and reaches the cutter mechanism 4.

[0084] 3 and 4, the cutter mechanism 4 has a cutter carriage 420 and a cutter frame 400. As shown in Fig. 4, the cutter mechanism 4 has a moving blade 412 and a fixed blade 411. The cutter carriage 420 rotatably holds the circular moving blade 412.

[0085] A cutter frame opening 409 is formed in the cutter frame 400. The cutter frame opening 409 has an inner width in the left-right direction that is larger than the width of the sheet SH so that the sheet SH guided by the guide surfaces 301 and 302 of the pre-cutting guide 300 can pass through.

[0086] The cutter frame 400 is made of metal, and specifically, is manufactured by pressing, punching, bending, etc. a steel plate. The downstream side of the guide surface 301 in the discharge direction DE1 enters a cutter frame opening 409.

[0087] The cutter frame 400 has a guide portion 402 above the cutter frame opening 409 and on the opposite side to the pre-cutting guide 300. The guide portion 402 guides the cutter carriage 420 in the left-right direction and prevents the cutter carriage 420 from coming off the guide portion 402.

[0088] That is, the cutter frame 400 holds the cutter carriage 420 so that the cutter carriage 420 can move in the left-right direction. Therefore, the cutter mechanism 4 cuts the conveyed sheet SH along the left-right direction.

[0089] 3, the cutter frame 400 has a cutting motor M2 and a timing belt 430. The cutting motor M2 is located on the left end side of the cutter frame 400 and above the cutter frame opening 409.

[0090] The timing belt 430 is wound around a drive pulley and a plurality of driven pulleys (not shown) and surrounds the cutter frame opening 409. The drive pulley and a plurality of driven pulleys (not shown) are rotatably supported by the cutter frame 400.

[0091] The cutter carriage 420 is connected to a portion of the timing belt 430 that extends in the left-right direction above the cutter frame opening 409 .

[0092] The cutting motor M2 drives a drive pulley (not shown) via a gear train to rotate it in the forward and reverse directions, thereby moving the cutter carriage 420 and the moving blade 412 left and right.

[0093] 3, the cutter carriage 420 (420A) is shown at a standby position on the right side of the cutter frame opening 409 where it does not interfere with the right edge of the sheet SH. The cutter carriage 420 (420B) is shown in a state in which it is in the middle of moving left and right. The cutter carriage 420 (420C) is shown at a folded-back position on the left side of the cutter frame opening 409 where it does not interfere with the left edge of the sheet SH.

[0094] That is, the cutter carriage 420 is movable between the position of cutter carriage 420A, which is the standby position in FIG. 3, and the position of cutter carriage 420C, which is the return position.

[0095] 4, the fixed blade 411 is fastened to the cutter frame 400 below the lower edge of the cutter frame opening 409. The fixed blade 411 extends upward and then bends to extend downstream in the discharge direction DE1. The cutting edge of the fixed blade 411 extends linearly in the left-right direction.

[0096] The moving blade 412 moves left and right while sliding against the cutting edge of the fixed blade 411. The moving blade 412 comes into contact with the sheet SH from the guide surface 301 side, that is, from above.

[0097] The cutter mechanism 4 uses a fixed blade 411 and a movable blade 412 to cut the sheet SH that has passed through the image forming unit 3 and the fixing unit 7 in the left-right direction. Since the fixed blade 411 is fixed to the cutter frame 400, the sheet SH is cut by the movement of the movable blade 412.

[0098] 3 and 4, the first guide 100 is located downstream of the fixed blade 411 and the movable blade 412 of the cutter mechanism 4 in the discharge direction DE1. The first guide 100 has a bottom wall 105 and a plurality of ribs 107. The first guide 100 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0099] The bottom wall 105 is curved and extends in the front-rear direction and the left-right direction. Each rib 107 protrudes upward from the upper surface of the bottom wall 105 and extends in the front-rear direction. The ribs 107 are spaced apart from each other in the left-right direction.

[0100] The first guide 100 has a first guide surface 101. The first guide surface 101 is formed by the tip of each rib 107. The first guide 100 guides the sheet SH, which is conveyed from the cutter mechanism 4 to the second conveying roller pair 29, by the first guide surface 101.

[0101] The first guide 100 rotatably supports the driven roller 29B of the second conveying roller pair 29. The driven roller 29B is rotatably supported on the downstream end 100D side of the first guide 100 in the discharge direction DE1.

[0102] A pressure spring (not shown) is positioned between the first guide 100 and the driven roller 29B. The pressure spring (not shown) applies a pressure to the driven roller 29B to ensure a nip pressure between the drive roller 29A and the driven roller 29B.

[0103] 3, the first guide 100 has a left wall 106L and a right wall 106R. The left wall 106L is connected to the left end of the bottom wall 105 and extends upward and in the front-to-rear direction. The right wall 106R is connected to the right end of the bottom wall 105 and extends upward and in the front-to-rear direction.

[0104] A shaft hole 102H is formed in the rear and lower position of the right wall 106R so as to penetrate in the left-right direction. The shaft hole 102H is a circular hole centered on the rotation axis X200 extending in the left-right direction. Although not shown in the figures, a shaft hole 102H is also formed in the left wall 106L.

[0105] 1 and 4, the second guide 200 has an upper wall 205. The upper wall 205 is bent so that the front portion is one step higher than the rear portion, and extends in the front-rear direction and also in the left-right direction. The second guide 200 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0106] The second guide 200 has a pair of rotation shafts (not shown) provided to the left of the left end of the upper wall 205 and to the right of the right end of the upper wall 205. The pair of rotation shafts (not shown) are inserted into shaft holes 102H in the left wall 106L and right wall 106R of the first guide 100, thereby enabling the second guide 200 to rotate about the rotation axis X200. The joint cover 50 to which the first guide 100 is fixed supports the second guide 200 so that the second guide 200 is rotatable about the rotation axis X200.

[0107] 4, the rotation axis X200 is located on the upstream end 200U side of the second guide 200 in the discharge direction DE1. The second guide 200 is biased downward by the biasing means 280, and is thereby positioned around the rotation axis X200 relative to the first guide 100.

[0108] The second guide 200 rotatably supports a drive roller 29A of the second conveying roller pair 29. The drive roller 29A is rotatably supported on a downstream end 200D side of the second guide 200 in the discharge direction DE1. The drive roller 29A and the driven roller 29B face each other at a nip position 29N.

[0109] Although not shown, the second guide 200 can be rotated upward around the rotation axis X200 by releasing the biasing force of the biasing means 280 on the second guide 200. As a result, the drive roller 29A moves upward away from the driven roller 29B, and the sheet SH jammed between the drive roller 29A and the driven roller 29B can be removed.

[0110] The second guide 200 has a plurality of ribs 207. Each rib 207 protrudes downward from the lower surface of the upper wall 205 and extends in the front-rear direction. The ribs 207 are spaced apart from each other in the left-right direction.

[0111] The second guide 200 has a second guide surface 202. The second guide surface 202 is formed by the tip of each rib 207 and faces the first guide surface 101.

[0112] An upstream side 202U of the second guide surface 202 in the discharge direction DE1 is inclined relative to a downstream side 202D of the second guide surface 202 in the discharge direction DE1 so as to move away from the first guide surface 101 toward the upstream end 200U of the second guide 200.

[0113] The second guide 200 guides the sheet SH, which is conveyed from the cutter mechanism 4 to the second conveying roller pair 29, by the second guide surface 202.

[0114] 3 and 4, the sheet sensor S4 is provided on the first guide 100. The sheet sensor S4 is located between the cutter frame 400 and the second conveying roller pair 29 in the discharge direction DE1.

[0115] More specifically, the sheet sensor S4 is located downstream of the fixed blade 411 and the movable blade 412 of the cutter mechanism 4 in the discharge direction DE1 and upstream of the second nip 29N of the first discharge roller pair 29 in the discharge direction DE1.

[0116] The sheet sensor S4 is an actuator that oscillates when the sheet SH comes into contact with it. The sheet sensor S4 detects the sheet SH that passes through the cutter mechanism 4 and then the first guide 100 and the second guide 200. The oscillation of the sheet sensor S4 is converted into an electrical signal by a photointerrupter (not shown) and transmitted to the control unit C1. The control unit C1 controls the timing when the cutter mechanism 4 cuts the sheet SH based on the detection result of the sheet sensor S4.

[0117] Specifically, the control unit C1 determines the timing when half the length of the sheet SH will reach the cutting position of the fixed blade 411 and the movable blade 412 based on the elapsed time since the sheet sensor S4 detected the leading edge of the sheet SH passing through the cutter mechanism 4 and the conveyance speed of the sheet SH. When that timing arrives, the control unit C1 controls the motor M1 to stop the third conveyance roller pair 70 and the second conveyance roller pair 29 that nip the sheet SH. Then, the control unit C1 controls the cutting motor M2 to move the movable blade 412 left and right. As a result, the cutter mechanism 4 cuts the sheet SH in half. Thereafter, the control unit C1 controls the motor M1 to rotate the third conveyance roller pair 70 and the second conveyance roller pair 29, and discharges the cut sheet SH (SH1) into two pieces onto the discharge tray 9.

[0118] <Drive force transmission mechanism> 5 and 6, the driving force transmission mechanism 500 has a metal plate frame 509 and a resin frame 508. The metal plate frame 509 extends in the front-rear and up-down directions like a flat plate.

[0119] As shown in FIG. 7, the resin frame 508 has a flat plate portion that extends flat in the front-rear and up-down directions, and a plurality of bosses and gear support shafts that each protrude leftward from the flat plate portion.

[0120] As shown in FIG. 6, the resin frame 508 is assembled to the sheet metal frame 509 by fitting or fastening the tips of the bosses to the sheet metal frame 509 with the flat plate portion separated from the sheet metal frame 509 to the right.

[0121] A motor M1 is fixed to the left side of the sheet metal frame 509. A drive shaft M1S of the motor M1 protrudes rightward and penetrates the sheet metal frame 509.

[0122] Although not shown in the drawings, the sheet metal frame 509 and the resin frame 508 are fixed to fixing portions formed in the support portion 57L of the joint cover 50.

[0123] 6 to 9, the driving force transmission mechanism 500 has a first drive train 510, a second drive train 520, and a third drive train 530. The driving force transmission mechanism 500 also has a switching unit 500C. The switching unit 500C has a first switching unit 520C and a second switching unit 530C.

[0124] <First drive train> As shown in Fig. 6, the first drive train 510 has a drive gear 511 that rotates integrally with the drive shaft M1S of the motor M1. The drive gear 511 is a helical gear. As shown in Fig. 8, when the motor M1 rotates forward, the drive gear 511 rotates clockwise. As shown in Fig. 9, when the motor M1 rotates reversely, the drive gear 511 rotates counterclockwise.

[0125] As shown in FIGS. 6 and 7, the first drive train 510 has transmission gears 512 and 513, a first upstream gear 514, and transmission gears 515 and 516 that are rotatably supported on respective gear support shafts of the resin frame 508.

[0126] Transmission gear 512, which is a helical gear, meshes with drive gear 511. Transmission gear 513, which is a spur gear, is formed integrally with transmission gear 512. Transmission gear 513 is located to the right of transmission gear 512 and has the same axis as transmission gear 512. Transmission gear 513 rotates integrally with transmission gear 512.

[0127] The first drive train 510 and the second drive train 520 share a first upstream gear 514. The first upstream gear 514, which is a spur gear, is located below the transmission gears 512 and 513 and meshes with the transmission gear 513. The first upstream gear 514 rotates around a first axis X501 that extends in the left-right direction.

[0128] The transmission gear 515, which is a spur gear, is located rearward and below the first upstream gear 514 and meshes with the first upstream gear 514. The transmission gear 516, which is also a spur gear, is located rearward of the transmission gear 515 and meshes with the transmission gear 515.

[0129] 5 and 8, the first drive train 510 has a final transmission gear 517. The final transmission gear 517 is located below the transmission gear 516 and is in mesh with the transmission gear 516.

[0130] Although not shown in the drawings, the final transmission gear 517 is fixed to the left end of the rotation shaft of the drive roller 28A of the first conveyor roller pair 28. As shown in Figures 8 and 9, the first drive train 510 transmits driving force from the motor M1 to the drive roller 28A of the first conveyor roller pair 28 when the motor M1 rotates forward and reverse.

[0131] <Second drive train> As shown in FIGS. 7 and 8, the second drive train 520 has the above-mentioned first upstream gear 514, a first downstream gear 522, and a first pendulum gear 521.

[0132] The first downstream gear 522, which is a spur gear, is located forward and above the first upstream gear 514. Although not shown in the figure, the first downstream gear 522 is fixed to the left end of the rotation shaft of the drive roller 29A of the second conveying roller pair 29.

[0133] As shown in Fig. 5, an elongated hole 507 is formed in the sheet metal frame 509. As shown in Fig. 6, an elongated hole 507 is also formed in the resin frame 508. As shown in Fig. 8, the elongated hole 507 is located at a position spaced forward from the first axis X501 and extends in the vertical direction so as to describe an arc centered on the first axis X501.

[0134] As shown in Fig. 6, first pendulum gear 521, which is a spur gear, has a pair of support shafts 521A. As shown in Fig. 7, first pendulum gear 521 has a cylindrical stepped portion that protrudes leftward from the center of the left side surface. Left support shaft 521A is a cylinder that protrudes leftward from the tip surface of the stepped portion and has a smaller diameter than the stepped portion. As shown in Fig. 6, right support shaft 521A is a cylinder that protrudes leftward from the right side surface of first pendulum gear 521 and has the same configuration as left support shaft 521A but on the opposite side.

[0135] 8 and 9, the left support shaft 521A is inserted into the elongated hole 507 of the sheet metal frame 509. The right support shaft 521A is inserted into the elongated hole 507 of the resin frame 508. As a result, the first pendulum gear 521 is engaged with the first upstream gear 514 in a state in which it can rotate on its own axis and revolve around the first axis center X501.

[0136] 6, a compression coil spring 521S is disposed between the sheet metal frame 509 and the outer peripheral edge of the left side surface of the first pendulum gear 521. The compression coil spring 521S applies frictional resistance to the first pendulum gear 521 to rotate the first pendulum gear 521 in the rotational direction of the first upstream gear 514.

[0137] By switching the rotation direction of the first upstream gear 514, the first pendulum gear 521 switches between a state in which it meshes with the first downstream gear 522, as shown in FIG. 9, and a state in which it is separated downward from the first downstream gear 522, as shown in FIG. 8.

[0138] The second drive train 520 branches off midway from the first drive train 510, and transmits driving force to the drive roller 29A of the second conveying roller pair 29 when the motor M1 rotates in reverse and the first pendulum gear 521 meshes with the first downstream gear 522, as shown in Figure 9.

[0139] <First switching unit> The first switching unit 520C is provided in the second drive train 520. The first switching unit 520C has a first upstream gear 514, a first downstream gear 522, and a first pendulum gear 521.

[0140] As shown in FIG. 8, when the control unit C1 rotates the motor M1 in the forward direction, the first switcher 520C is brought into a first disconnection state in which the second drive train 520 is disconnected midway.

[0141] As shown in FIG. 9, when the control unit C1 rotates the motor M1 in the reverse direction, the first switch unit 520C is brought into the first connection state in which the second drive train 520 is not interrupted.

[0142] <Third drive train> 6 and 7, the third drive train 530 has a second upstream gear 531. The second upstream gear 531, which is a helical gear, is formed integrally with the transmission gear 515. The second upstream gear 531 is located to the left of the transmission gear 515. The second upstream gear 531 rotates integrally with the transmission gear 515 around a second axis X502 extending in the left-right direction.

[0143] The third drive train 530 has a second downstream gear 533 and a second pendulum gear 532. The second downstream gear 533, which is a helical gear, is spaced rearward from the second upstream gear 531. Although not shown, the second downstream gear 533 is rotatably supported on a gear support shaft formed in the support portion 57L of the joint cover 50.

[0144] An arm 530A that can swing about a second axis X502 is located to the left of the second upstream gear 531. A second pendulum gear 532, which is a helical gear, is rotatably supported at the tip of the arm 530A.

[0145] The second pendulum gear 532 is meshed with the second upstream gear 531 by the arm 530A in a state in which it can rotate on its own axis and revolve around the second axis X502.

[0146] Although not shown, a leaf spring is disposed between the tip of arm 530A and second pendulum gear 532. The leaf spring applies frictional resistance to second pendulum gear 532 to rotate second pendulum gear 532 in the rotational direction of second upstream gear 531.

[0147] By switching the rotation direction of the second upstream gear 531, the second pendulum gear 532 switches between a state in which it meshes with the second downstream gear 533, as shown in Figure 9, and a state in which it is separated downward and forward from the second downstream gear 533, as shown in Figure 8.

[0148] As shown in FIGS. 6 and 7, the third drive train 530 includes transmission gears 534 , 535 , 536 , 537 and a final transmission gear 538 .

[0149] Although not shown, the transmission gear 534 , which is a helical gear, is located rearward of the second downstream gear 533 and is in mesh with the second downstream gear 533 .

[0150] Transmission gear 535, which is a spur gear, is formed integrally with transmission gear 534. Transmission gear 535 is located to the right of transmission gear 534 and has the same axis as transmission gear 534. Transmission gear 535 rotates integrally with transmission gear 534.

[0151] Although not shown, the transmission gears 534 and 535 are rotatably supported on a gear support shaft formed in the support portion 57L of the joint cover 50.

[0152] Although not shown, the transmission gears 536 and 537 and the final transmission gear 538 are located on the left side of the cutting cover 7 and are rotatably supported by the pre-cutting cover 80 .

[0153] The transmission gear 536 is located rearward of the transmission gears 534 and 535 and meshes with the transmission gear 535. The transmission gear 537 is located above the transmission gear 536 and meshes with the transmission gear 536.

[0154] The final transmission gear 538 is located forward and above the transmission gear 537 and is in mesh with the transmission gear 537. Although not shown in the drawings, the final transmission gear 538 is fixed to the left end of the rotation shaft of the drive roller 70A of the third conveying roller pair 70.

[0155] The third drive train 530 branches off midway from the first drive train 510, and transmits driving force to the drive roller 70A of the third conveying roller pair 70 when the motor M1 rotates in reverse and the second pendulum gear 532 meshes with the second downstream gear 533, as shown in Figure 9.

[0156] <Second switching section> The second switching unit 530C is provided in the third drive train 530. The second switching unit 530C has a second upstream gear 531, a second downstream gear 533, and a second pendulum gear 532.

[0157] As shown in FIG. 8, when the control unit C1 rotates the motor M1 in the forward direction, the second switch unit 530C is brought into a second disconnection state in which the third drive train 530 is disconnected midway.

[0158] As shown in FIG. 9, when the control unit C1 rotates the motor M1 in the reverse direction, the second switching unit 530C is brought into the second connection state in which the third drive train 530 is not interrupted.

[0159] <First Discharge Operation and Second Discharge Operation> When the sheet SH that has passed through the image forming unit 3 and the fixing unit 7 is to be discharged onto the discharge tray 9 without passing through the cutter mechanism 4, the control unit C1 executes a first discharge operation to discharge the sheet SH from the first discharge path PD1.

[0160] The control unit C1 guides the sheet SH that has passed through the image forming unit 3 and the fixing unit 7 to the cutter mechanism 4, and when the cutting process is performed and the sheet SH that has passed through the cutter mechanism 4 is discharged to the discharge tray 9, the control unit C1 performs a second discharge operation to discharge the sheet SH from the second discharge path PD2.

[0161] When performing the first discharge operation and the second discharge operation, the control unit C1 indirectly controls the first switching unit 520C and the second switching unit 530C, which are pendulum gear type clutches, by controlling the forward rotation, reverse rotation, and stop of the motor M1.

[0162] As shown in FIG. 8, when performing the first discharge operation, the control unit C1 rotates the motor M1 in the forward direction, thereby moving the first pendulum gear 521 away from the first downstream gear 522, thereby setting the first switching unit 520C in a first disconnection state in which the second drive train 520 is disconnected midway, and moving the second pendulum gear 532 away from the second downstream gear 533, thereby setting the second switching unit 530C in a second disconnection state in which the third drive train 530 is disconnected midway.

[0163] The first drive train 510 transmits a driving force to the drive roller 28A of the first conveyor roller pair 28.

[0164] In other words, when performing the first discharge operation, the switching unit 500C transmits the driving force to the drive roller 28A of the first conveying roller pair 28, while the first switching unit 520C cuts off the transmission of the driving force to the drive roller 29A of the second conveying roller pair 29, and the second switching unit 530C cuts off the transmission of the driving force to the drive roller 70A of the third conveying roller pair 70.

[0165] When performing the second discharge operation, the control unit C1 reverses the rotation of the motor M1 to mesh the first pendulum gear 521 with the first downstream gear 522, thereby setting the first switching unit 520C in a first connection state in which the second drive train 520 is not interrupted, and meshes the second pendulum gear 532 with the second downstream gear 533, thereby setting the second switching unit 530C in a second connection state in which the third drive train 530 is not interrupted.

[0166] In other words, when performing the second discharge operation, the switching unit 500C transmits the driving force to the drive roller 29A of the second conveying roller pair 29 via the first switching unit 520C, and also transmits the driving force to the drive roller 70A of the third conveying roller pair 70 via the second switching unit 530C.

[0167] When performing the second discharge operation, the control unit C1 rotates the motor M1 in the reverse direction, thereby transmitting a driving force to the drive roller 28A of the first conveying roller pair 28 via the first drive train 510 and rotating the drive roller 28A in the reverse direction.

[0168] During the second discharge operation, the control unit C1 stops the motor M1 at a timing determined based on the detection result of the sheet sensor S4, and then controls the cutting motor M2 to move the movable blade 412 in the left-right direction. As a result, the sheet SH nipped between the stopped third conveyor roller pair 70 and the second conveyor roller pair 29 is cut in half. During the cutting process, the control unit C1 controls the motor M1 to supply a current necessary to maintain the phase of the motor M1, thereby restricting the movement of the sheet SH. Thereafter, the control unit C1 reversely rotates the motor M1 again to rotate the third conveyor roller pair 70 and the second conveyor roller pair 29, and discharges the cut sheet SH (SH1) into two pieces onto the discharge tray 9.

[0169] The reduction ratio from the motor M1 to the drive roller 70A of the third conveyor roller pair 70 is set to be larger than the reduction ratio from the motor M1 to the drive roller 29A of the second conveyor roller pair 29. As shown in Figure 4, the diameter RD2 of the drive roller 29A of the second conveyor roller pair 29 is equal to the diameter RD3 of the drive roller 70A of the third conveyor roller pair 70.

[0170] As a result, the conveying distance TD2 (mm) of the second conveying roller pair 29 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1 is greater than the conveying distance TD3 (mm) of the third conveying roller pair 70 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1.

[0171] <Seat movement distance> 2, the maximum length of the sheet SH that can be accommodated by the image forming apparatus 1 is the maximum length of the sheet SH that can be supported by the sheet cassette 10C. The maximum length of the sheet SH that can be accommodated by the image forming apparatus 1 is defined as LS1.

[0172] As shown in Figure 10, the movement distance of the sheet SH from the fixing nip 7N to the detection position of the sheet sensor S4 is defined as LR1. The movement distance LR1 is longer than the maximum length LS1. In other words, when the sheet SH passing through the cutter mechanism 4 abuts against the sheet sensor S4, the trailing edge of the sheet SH is away from the fixing nip 7N. This prevents the fixing nip 7N from affecting the detection accuracy of the sheet sensor S4.

[0173] The travel distance of the sheet SH from the fixing nip 7N to the cutting position of the fixed blade 411 and the movable blade 412 in the cutter mechanism 4 is defined as LC1. The travel distance LC1 is longer than half the maximum length LS1. In other words, when the sheet SH stops being cut by the cutter mechanism 4, the trailing edge of the sheet SH is away from the fixing nip 7N.

[0174] The movement distance of the sheet SH from the fixing nip portion 7N to the nip position of the post-fixing conveying roller pair 25 is defined as LD1. The movement distance of the sheet SH from the nip position of the post-fixing conveying roller pair 25 to the cutting position of the fixed blade 411 and the movable blade 412 in the cutter mechanism 4 is LC1-LD1. The movement distance LC1-LD1 is longer than half the maximum length LS1. In other words, when the sheet SH to be cut by the cutter mechanism 4 stops, the trailing edge of the sheet SH is away from the nip position of the post-fixing conveying roller pair 25.

[0175] <Action and effect> In the image forming apparatus 1 of the first embodiment, as shown in FIG. 2, the first discharge operation, in which the sheet SH that has passed through the image forming unit 3 is discharged as is, is performed more frequently than the second discharge operation, in which the sheet SH that has passed through the image forming unit 3 is cut and then discharged.

[0176] As shown in Figure 8, the switching unit 500C uses the first switching unit 520C to block the transmission of driving force to the drive roller 29A of the second conveying roller pair 29, which does not contribute to the conveying of the sheet SH during the first discharge operation, which is performed frequently, thereby eliminating the driving noise associated with the second conveying roller pair 29.

[0177] In the second discharge operation, the drive roller 28A of the first conveying roller pair 28, which does not contribute to the transport of the sheet SH, is driven together with the drive roller 29A of the second conveying roller pair 29, but since the second discharge operation is performed infrequently, the drive noise associated with the first conveying roller pair 28 is unlikely to be a problem.

[0178] Therefore, the image forming apparatus 1 of the first embodiment can reduce driving noise in a configuration including the first discharge path PD1 and the second discharge path PD2. Also, the image forming apparatus 1 can suppress wear of the second conveying roller pair 29, thereby achieving a longer life for the second conveying roller pair 29.

[0179] 8 and 9, in this image forming apparatus 1, the second drive train 520 branches off midway through the first drive train 510. The first switcher 520C cuts off the transmission of drive force to the drive roller 29A of the second conveyor roller pair 29 when performing the first discharge operation, and transmits drive force to the drive roller 29A of the second conveyor roller pair 29 when performing the second discharge operation. With this configuration, the first conveyor roller pair 28 and the second conveyor roller pair 29 share the upstream side of the first drive train 510, thereby simplifying the drive force transmission mechanism 500 and saving space.

[0180] Furthermore, in this image forming apparatus 1, the drive force transmission mechanism 500 also transmits drive force from the motor M1 to the drive roller 70A of the third conveyor roller pair 70. When performing the first discharge operation, the switching unit 500C blocks the transmission of drive force to the drive roller 29A of the second conveyor roller pair 29 and the drive roller 70A of the third conveyor roller pair 70. When performing the second discharge operation, the switching unit 500C transmits drive force to at least the drive roller 29A of the second conveyor roller pair 29 and the drive roller 70A of the third conveyor roller pair 70. This configuration eliminates drive noise associated with the second conveyor roller pair 29 and the third conveyor roller pair 70 during the first discharge operation, and allows the second conveyor roller pair 29 and the third conveyor roller pair 70 to appropriately convey the sheet SH during the second discharge operation. Furthermore, when cutting the sheet SH, the second conveyor roller pair 29 and the third conveyor roller pair 70 stop in a state where they nip the sheet SH, thereby preventing the sheet SH from shifting and reducing the quality of the cutting process.

[0181] 2, the image forming apparatus 1 includes a discharge tray 9 that supports sheets SH discharged from the first discharge path PD1 and the second discharge path PD2. The second conveyance roller pair 29 is located downstream of the cutter mechanism 4 in the discharge direction DE1 in which the sheets SH are conveyed along the second discharge path PD2. The third conveyance roller pair 70 is located upstream of the cutter mechanism 4 in the discharge direction DE1. With this configuration, during the first discharge operation, it is possible to eliminate drive noise associated with at least the second conveyance roller pair 29 out of the second conveyance roller pair 29 that is located close to the user who picks up the sheets SH supported on the discharge tray 9 and the third conveyance roller pair 70 that is located farther from the user, thereby further reducing drive noise.

[0182] Furthermore, in this image forming apparatus 1, as shown in FIGS. 8 and 9, the second drive train 520 and the third drive train 530 branch off midway through the first drive train 510. The first switcher 520C cuts off the transmission of drive force to the drive roller 29A of the second conveyor roller pair 29 when performing the first discharge operation, and transmits the drive force to the drive roller 29A of the second conveyor roller pair 29 when performing the second discharge operation. The second switcher 530C cuts off the transmission of drive force to the drive roller 70A of the third conveyor roller pair 70 when performing the first discharge operation, and transmits the drive force to the drive roller 70A of the third conveyor roller pair 70 when performing the second discharge operation. With this configuration, the first conveyor roller pair 28, the second conveyor roller pair 29, and the third conveyor roller pair 70 share the upstream side of the first drive train 510, thereby simplifying the drive force transmission mechanism 500 and saving space. Furthermore, since the driving noise associated with the second conveyor roller pair 29 and the third conveyor roller pair 70 can be eliminated during the first discharge operation, the driving noise can be further reduced, and wear on the second conveyor roller pair 29 and the third conveyor roller pair 70 can be suppressed, thereby extending the lifespan of the second conveyor roller pair 29 and the third conveyor roller pair 70. Furthermore, because the first switcher 520C is a pendulum gear clutch, the stopped second conveyor roller pair 29 is less likely to rotate due to driving resistance. Therefore, even if the sheet SH pulls the second conveyor roller pair 29 to rotate in the reverse direction when cutting the sheet SH, the second conveyor roller pair 29 can restrict the movement of the sheet SH. Furthermore, because the second switcher 530C is a pendulum gear clutch, the stopped third conveyor roller pair 70 is less likely to rotate due to driving resistance. Therefore, even if the sheet SH pulls the third conveyor roller pair 70 to rotate in the forward direction when cutting the sheet SH, the third conveyor roller pair 70 can restrict the movement of the sheet SH.

[0183] In this image forming apparatus 1, the post-processing is a cutting process that cuts the sheet SH in the left-right direction. The drive source is a motor M1. The conveying distance TD2 (mm) of the second conveying roller pair 29 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1 is greater than the conveying distance TD3 (mm) of the third conveying roller pair 70 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1. With this configuration, the second conveying roller pair 29, which is located downstream of the cutter mechanism 4 in the discharge direction DE1, can always pull and apply tension to the sheet SH, making it easier for the cutter mechanism 4 to cut the sheet SH. Furthermore, when the cut sheet SH (SH1) is conveyed, a gap can be secured between the two cut sheets SH (SH1) located upstream and downstream in the discharge direction DE1.

[0184] Furthermore, in this image forming apparatus 1, the reduction ratio from the motor M1 to the drive roller 70A of the third conveying roller pair 70 is greater than the reduction ratio from the motor M1 to the drive roller 29A of the second conveying roller pair 29. With this configuration, even if the diameter RD2 of the drive roller 29A and the diameter RD3 of the drive roller 70A of the second conveying roller pair 29 are made equal and the drive roller 29A and the drive roller 70A of the third conveying roller pair 70 use the same components, the conveying distance TD2 (mm) of the second conveying roller pair 29 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1 can be greater than the conveying distance TD3 (mm) of the third conveying roller pair 70 per predetermined rotation amount AM1 (e.g., N rotations) of the motor M1.

[0185] Furthermore, in this image forming apparatus 1, the control unit C1 sets the first switching unit 520C to the first disconnected state and the second switching unit 530C to the second disconnected state when performing the first discharge operation. The control unit C1 sets the first switching unit 520C to the first connected state and the second switching unit 530C to the second connected state when performing the second discharge operation. This control by the control unit C1 eliminates drive noise associated with the second conveyor roller pair 29 and the third conveyor roller pair 70 during the first discharge operation. This further reduces drive noise and suppresses wear on the second conveyor roller pair 29 and the third conveyor roller pair 70, thereby extending the lifespan of the second conveyor roller pair 29 and the third conveyor roller pair 70.

[0186] Furthermore, in this image forming apparatus 1, first switching unit 520C has first upstream gear 514, first downstream gear 522, and first pendulum gear 521. Second switching unit 530C has second upstream gear 531, second downstream gear 533, and second pendulum gear 532. When performing the first discharge operation, control unit C1 rotates motor M1 in the forward direction, thereby moving first pendulum gear 521 away from first downstream gear 522 to set first switching unit 520C to the first disconnection state, and moving second pendulum gear 532 away from second downstream gear 533 to set second switching unit 530C to the second disconnection state. When performing the second discharge operation, the controller C1 rotates the motor M1 in the reverse direction, thereby meshing the first pendulum gear 521 with the first downstream gear 522 to set the first switching unit to the first connected state, and meshing the second pendulum gear 532 with the second downstream gear 533 to set the second switching unit 530C to the second connected state. The first switching unit 520C and the second switching unit 530C are pendulum gear clutches. Thus, by simply switching the motor M1 between forward and reverse rotation, the controller C1 can switch the first switching unit 520C between the first disconnected state and the first connected state, and can switch the second switching unit 530C between the second disconnected state and the second connected state. As a result, the image forming apparatus 1 can achieve lower component costs and space savings compared to when electromagnetic clutches or solenoids are used for the first switching unit 520C and the second switching unit 530C.

[0187] Furthermore, in this image forming apparatus 1, the control unit C1 controls the motor M1 to supply a current necessary to maintain the phase of the motor M1 during the cutting process. With this configuration, even if the sheet SH pulls the second conveying roller pair 29 so as to rotate in the reverse direction when the cutting process is performed on the sheet SH, the second conveying roller pair 29 can restrict the movement of the sheet SH.

[0188] Example 2 11, in the image forming apparatus of the second embodiment, the second switching unit 530C of the image forming apparatus 1 of the first embodiment is eliminated from the third drive train 530. In other words, the switching unit 500C has only the first switching unit 520C provided in the second drive train 520.

[0189] Specifically, the second pendulum gear 532 is changed to a configuration in which it is rotatably supported on a gear support shaft (not shown) formed in the support portion 57L of the joint cover 50, instead of on the arm 530A. The second pendulum gear 532 is constantly meshed with the second upstream gear 531 and also constantly meshed with the second downstream gear 533.

[0190] <First Discharge Operation and Second Discharge Operation> When performing the first discharge operation, the control unit C1 rotates the motor M1 in the forward direction, thereby moving the first pendulum gear 521 away from the first downstream gear 522 and setting the first switching unit 520C to the first disconnecting state.

[0191] The first drive train 510 transmits a drive force to the drive roller 28A of the first conveyor roller pair 28. The third drive train 530 transmits a drive force to the drive roller 70A of the third conveyor roller pair 70.

[0192] In other words, when performing the first discharge operation, the switching unit 500C transmits driving force to the drive roller 28A of the first conveying roller pair 28 and the drive roller 70A of the third conveying roller pair 70, while the first switching unit 520C cuts off the transmission of driving force to the drive roller 29A of the second conveying roller pair 29.

[0193] When performing the second discharge operation, the control unit C1 rotates the motor M1 in the reverse direction, thereby meshing the first pendulum gear 521 with the first downstream gear 522 and setting the first switching unit 520C to the first connection state.

[0194] The third drive train 530 transmits a driving force to the drive roller 70A of the third conveying roller pair 70.

[0195] In other words, when performing the second discharge operation, the switching unit 500C transmits driving force to the drive roller 70 of the third conveying roller pair 70 via the third drive train 530, and transmits driving force to the drive roller 29A of the second conveying roller pair 29 via the first switching unit 520C.

[0196] When performing the second discharge operation, the control unit C1 rotates the motor M1 in the reverse direction, thereby transmitting a driving force to the drive roller 28A of the first conveying roller pair 28 via the first drive train 510 and rotating the drive roller 28A in the reverse direction.

[0197] <Action and effect> The image forming apparatus of the second embodiment can reduce driving noise in a configuration including the first discharge path PD1 and the second discharge path PD2, similar to the image forming apparatus 1 of the first embodiment. Furthermore, the image forming apparatus 1 can suppress wear of the second conveying roller pair 29, thereby realizing a longer life for the second conveying roller pair 29.

[0198] In this image forming apparatus, the second drive train 520 and the third drive train 530 branch off midway through the first drive train 510. The switching unit 500C has only a first switching unit 520C provided in the second drive train 520. The first switching unit 520C blocks the transmission of drive force to the second conveyance roller pair 29 when performing the first discharge operation, and transmits drive force to the second conveyance roller pair 29 when performing the second discharge operation. With this configuration, the first conveyance roller pair 28, the second conveyance roller pair 29, and the third conveyance roller pair 70 share the upstream side of the first drive train 510, thereby simplifying the drive force transmission mechanism 500 and saving space. Furthermore, since the switching unit 500C has only the first switching unit 520C provided in the second drive train 520, the gears from the motor M1 to the third conveyor roller pair 70 are always kept engaged, and the stopped third conveyor roller pair 70 is unlikely to rotate due to drive resistance. Therefore, even if the sheet SH pulls the third conveyor roller pair 70 to rotate forward when cutting the sheet SH, the third conveyor roller pair 70 can restrict the movement of the sheet SH. Furthermore, because the first switching unit 520C is a pendulum gear clutch, the stopped second conveyor roller pair 29 is unlikely to rotate due to drive resistance. Therefore, even if the sheet SH pulls the second conveyor roller pair 29 to rotate backward when cutting the sheet SH, the second conveyor roller pair 29 can restrict the movement of the sheet SH.

[0199] Furthermore, in this image forming apparatus, the first switching unit 520C has a first upstream gear 514, a first downstream gear 522, and a first pendulum gear 521. When performing the first discharge operation, the control unit C1 rotates the motor M1 in the forward direction, thereby separating the first pendulum gear 521 from the first downstream gear 522 and setting the first switching unit 520C to the first disconnected state. When performing the second discharge operation, the control unit C1 rotates the motor M1 in the reverse direction, thereby engaging the first pendulum gear 521 with the first downstream gear 522 and setting the first switching unit 520C to the first connected state. The first switching unit 520C is a pendulum gear clutch. As a result, the control unit C1 can switch the first switching unit 520C between the first disconnected state and the first connected state simply by switching the motor M1 between forward and reverse rotation. As a result, this image forming apparatus can achieve lower component costs and space savings for first switching unit 520C compared to when an electromagnetic clutch or solenoid is used.

[0200] Example 3 In the image forming device 1 of Example 1, the diameter RD2 of the drive roller 29A and the diameter RD3 of the drive roller 70A are equal, but in the image forming device of Example 3, the diameter RD2 of the drive roller 29A of the second conveying roller pair 29 is changed to a value larger than the diameter RD3 of the drive roller 70A of the third conveying roller pair 70.

[0201] With this configuration, in the image forming apparatus of Example 3, even if the reduction ratio from motor M1 to drive roller 29A of second conveying roller pair 29 and the reduction ratio from motor M1 to drive roller 70A of third conveying roller pair 70 are the same, the conveying distance TD2 (mm) of second conveying roller pair 29 per predetermined rotation amount AM1 (e.g., N rotations) of motor M1 can be made greater than the conveying distance TD3 (mm) of third conveying roller pair 70 per predetermined rotation amount AM1 (e.g., N rotations) of motor M1.

[0202] The present invention has been described above in accordance with Examples 1 to 3, but it goes without saying that the present invention is not limited to the above Examples 1 to 3 and can be modified and applied as appropriate within the scope of the invention.

[0203] In Examples 1 to 3, the image forming apparatus of the present invention is embodied as image forming apparatus 1, which is a multifunction peripheral equipped with an image reading device above, but the present invention is not limited to this configuration. For example, the configuration of the present invention may be applied to an image forming apparatus that is not a multifunction peripheral. Furthermore, the configuration of the present invention may be applied not only to a monochrome electrophotographic image forming apparatus as in this embodiment, but also to a color electrophotographic image forming apparatus or a printing apparatus using another printing method, such as an inkjet method or a thermal method.

[0204] In the first to third embodiments, the post-processing section is the cutter mechanism 4 and the predetermined post-processing is cutting, but the present invention is not limited to this configuration. For example, the predetermined post-processing may be punching, stapling, etc.

[0205] In the first to third embodiments, the second conveying roller pair 29 is located downstream of the cutter mechanism 4 in the discharge direction DE1, but the present invention is not limited to this configuration. For example, the present invention also includes a configuration in which the second conveying roller pair is located upstream of the post-processing section in the discharge direction.

[0206] The present invention also includes a configuration in which the first switching unit 520C according to the first embodiment is removed from the second drive train 520, and the switching unit 500C has only the second switching unit 530C provided in the third drive train 530.

[0207] In the first to third embodiments, the control unit C1 controls the motor M1 to supply a current necessary to maintain the phase of the motor M1 during the cutting process, thereby restricting the movement of the sheet SH, but the present invention is not limited to this configuration. For example, the control unit may stop supplying power to the motor during the cutting process. [Explanation of symbols]

[0208] 1...image forming apparatus, SH...sheet, 3...image forming unit PD1: First discharge path, 4: Post-processing section (cutter mechanism) PD2: Second discharge path, 28: First conveying roller pair 29... second conveying roller pair, M1... driving source (motor) 500...driving force transmission mechanism, 500C...switching unit 510...first drive train, 520...second drive train 520C...first switching unit, 70...third conveying roller pair 9...Ejection tray, DE1...Ejection direction 530...Third drive train, 530C...Second switching unit AM1: Specified motor rotation amount TD2: Transport distance of the second transport roller pair per predetermined rotation of the motor TD3: Transport distance of the third transport roller pair per specified rotation of the motor 29A...Drive roller of second conveying roller pair 70A...Drive roller of the third conveying roller pair RD2: Diameter of the drive roller of the second conveyor roller pair RD3: Diameter of the drive roller of the third conveying roller pair C1…Control unit, X501…1st axis center 514...first upstream gear, 522...first downstream gear 521...1st pendulum gear, X502...2nd shaft center 531...second upstream gear, 533...second downstream gear 532...Second pendulum gear

Claims

1. an image forming unit that forms an image on a sheet; a first discharge path for discharging the sheet that has passed through the image forming unit; a second discharge path that guides the sheet that has passed through the image forming unit to a post-processing unit that performs predetermined post-processing, and discharges the sheet that has passed through the post-processing unit; a first conveying roller pair that conveys the sheet along the first discharge path; a second conveying roller pair that conveys the sheet along the second discharge path; one driving source that generates a driving force; a driving force transmission mechanism that transmits the driving force from the driving source to the first conveying roller pair and the second conveying roller pair; An image forming apparatus comprising: The image forming apparatus is characterized in that the driving force transmission mechanism has a switching unit that transmits the driving force to the first conveying roller pair when performing a first discharge operation to discharge a sheet from the first discharge path, and cuts off the transmission of the driving force to the second conveying roller pair, and that transmits the driving force to at least the second conveying roller pair when performing a second discharge operation to discharge a sheet from the second discharge path.

2. the driving force transmission mechanism includes a first drive train that transmits the driving force from the driving source to the first conveying roller pair; a second drive train that branches off from the first drive train and transmits the drive force to the second conveying roller pair, the switching unit includes a first switching unit provided in the second drive train, 2. The image forming apparatus according to claim 1, wherein the first switching unit interrupts the transmission of the driving force to the second conveying roller pair when performing the first discharge operation, and transmits the driving force to the second conveying roller pair when performing the second discharge operation.

3. a third conveying roller pair that conveys the sheet along the second discharge path, the third conveying roller pair being located on an opposite side of the post-processing section from the second conveying roller pair; the driving force transmission mechanism transmits the driving force from the driving source to the third conveying roller pair as well; 2. The image forming apparatus according to claim 1, wherein the switching unit cuts off the transmission of the driving force to at least the second pair of conveying rollers when performing the first discharge operation, and transmits the driving force to at least the second pair of conveying rollers and the third pair of conveying rollers when performing the second discharge operation.

4. a discharge tray that supports sheets discharged from the first discharge path and the second discharge path; the second conveying roller pair is located downstream of the post-processing section in a discharge direction in which the sheet is conveyed along the second discharge path, 4. The image forming apparatus according to claim 3, wherein the third conveying roller pair is located upstream of the post-processing section in the discharge direction.

5. the driving force transmission mechanism includes a first drive train that transmits the driving force from the driving source to the first conveying roller pair; a second drive train branching from the first drive train and transmitting the driving force to the second conveying roller pair; a third drive train that branches off from the first drive train and transmits the drive force to the third conveying roller pair, the switching unit has only a first switching unit provided in the second drive train, 5. The image forming apparatus of claim 4, wherein the first switching unit interrupts transmission of the driving force to the second conveying roller pair when performing the first discharge operation, and transmits the driving force to the second conveying roller pair when performing the second discharge operation.

6. the driving force transmission mechanism includes a first drive train that transmits the driving force from the driving source to the first conveying roller pair; a second drive train branching from the first drive train and transmitting the driving force to the second conveying roller pair; a third drive train that branches off from the first drive train and transmits the drive force to the third conveying roller pair, the switching unit includes a first switching unit provided in the second drive train and a second switching unit provided in the third drive train, the first switching unit interrupts transmission of the driving force to the second conveying roller pair when performing the first discharge operation, and transmits the driving force to the second conveying roller pair when performing the second discharge operation; 5. The image forming apparatus according to claim 4, wherein the second switching unit cuts off the transmission of the driving force to the third conveying roller pair when performing the first discharge operation, and transmits the driving force to the third conveying roller pair when performing the second discharge operation.

7. the post-processing is a cutting process of cutting the sheet along a width direction perpendicular to the discharge direction, the drive source is a motor, 7. The image forming apparatus according to claim 4, wherein a conveying distance of the second conveying roller pair per predetermined rotation amount of the motor is greater than a conveying distance of the third conveying roller pair per predetermined rotation amount.

8. 8. The image forming apparatus according to claim 7, wherein the diameter of the drive roller of the second transport roller pair is larger than the diameter of the drive roller of the third transport roller pair.

9. 8. The image forming apparatus according to claim 7, wherein a reduction ratio from the motor to the drive roller of the third transport roller pair is greater than a reduction ratio from the motor to the drive roller of the second transport roller pair.

10. a control unit that controls the image forming unit, the drive source, and the switching unit, The first switching unit includes a first upstream gear that rotates about a first axis; a first downstream gear spaced from the first upstream gear; a first pendulum gear that is meshed with the first upstream gear in a state that is rotatable and revolvable about the first axis, and that switches between a state in which it meshes with the first downstream gear and a state in which it is separated from the first downstream gear by switching the rotation direction of the first upstream gear; the control unit causes the drive source to rotate in the forward direction when performing the first discharge operation, thereby moving the first pendulum gear away from the first downstream gear and setting the first switching unit to a first disconnection state in which the second drive train is interrupted midway; The image forming apparatus according to claim 5, wherein the control unit causes the drive source to rotate in the reverse direction when performing the second discharge operation, thereby meshing the first pendulum gear with the first downstream gear and setting the first switching unit to a first connection state in which the second drive train is not interrupted.

11. a control unit that controls the image forming unit, the drive source, and the switching unit, when performing the first discharging operation, the control unit sets the first switching unit to a first disconnection state in which the second drive train is disconnected midway, and sets the second switching unit to a second disconnection state in which the third drive train is disconnected midway; The image forming apparatus of claim 6, wherein the control unit, when performing the second discharge operation, sets the first switching unit to a first connection state in which the second drive train is not interrupted, and sets the second switching unit to a second connection state in which the third drive train is not interrupted.

12. The first switching unit includes a first upstream gear that rotates about a first axis; a first downstream gear spaced from the first upstream gear; a first pendulum gear that is meshed with the first upstream gear in a state that is rotatable and revolvable about the first axis, and that switches between a state in which it meshes with the first downstream gear and a state in which it is separated from the first downstream gear by switching the rotation direction of the first upstream gear; The second switching unit includes a second upstream gear that rotates about a second axis; a second downstream gear spaced from the second upstream gear; a second pendulum gear that is meshed with the second upstream gear in a state that is rotatable and revolvable around the second axis, and that switches between a state in which it meshes with the second downstream gear and a state in which it is separated from the second downstream gear by switching the rotation direction of the second upstream gear; the control unit causes the drive source to rotate in the forward direction when performing the first discharge operation, thereby moving the first pendulum gear away from the first downstream gear and setting the first switching unit to a first disconnection state in which the second drive train is interrupted midway, and moving the second pendulum gear away from the second downstream gear and setting the second switching unit to a second disconnection state in which the third drive train is interrupted midway; 12. The image forming apparatus according to claim 11, wherein the control unit reversely rotates the drive source when performing the second discharge operation, thereby meshing the first pendulum gear with the first downstream gear to set the first switching unit to a first connection state in which the second drive train is not interrupted, and meshing the second pendulum gear with the second downstream gear to set the second switching unit to a second connection state in which the third drive train is not interrupted.

13. the post-processing is a cutting process of cutting the sheet along a width direction perpendicular to the discharge direction, the drive source is a motor, 13. The image forming apparatus according to claim 10, wherein the control unit controls the motor to supply a current required to maintain the phase of the motor during the cutting process.

Images