Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent a sheet ejected along a first ejection path from being curled with high reliability.SOLUTION: An image forming apparatus 1 comprises a housing 9, an image forming unit 3, a conveying unit 26, a re-conveying unit 30, a cover 100 and a flapper 50. The image forming apparatus 1 further comprises a connection part 60 that connects the cover 100 and the flapper 50 to each other, the connection part 60 moving the flapper 50 from a first position to a second position in conjunction with the movement of the cover 100 from a closing position to an opening position, and moving the flapper 50 from the second position to the first position in conjunction with the movement of the cover 100 from the opening position to the closing position. At the second position, the flapper 50 projects toward downstream in an ejection direction DE1 from the inside of the housing 9 and can be brought into contact with a sheet SH conveyed by the conveying unit 26 from above.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an example of a conventional image forming apparatus. This image forming apparatus includes an apparatus main body, an image forming unit, a first discharge roller, and a guide member.

[0003] The apparatus main body has an opening. The image forming unit is located inside the apparatus main body and forms an image on a passing sheet.

[0004] The first discharge roller has a driving roller and a driven roller. The first discharge roller discharges the sheet that has passed through the image forming unit along a face-up discharge path in which the surface on which the image is formed faces upward in the discharge direction, or a face-down discharge path that guides and discharges above the face-up discharge path.

[0005] The discharge direction of the first discharge roller is an upwardly inclined direction toward the left side of the paper surface in FIGS. 1 and 2 of Patent Document 1.

[0006] The guide member is movable between a closed position that closes the opening and an open position that moves downstream and downward in the discharge direction from the closed position to open the opening. The closed position of the guide member is a position where the sheet that has passed through the image forming unit heads toward the face-down discharge path. The open position of the guide member is a position where the sheet that has passed through the image forming unit heads toward the face-up discharge path. The guide member supports the sheet discharged through the opening along the face-up discharge path in the open position.

[0007] The image forming apparatus further includes a mounting member and a torsion spring. The mounting member is movable between a first position and a second position. The torsion spring biases the mounting member to move from the first position to the second position.

[0008] When the guide member swings from the open position to the closed position, the projection of the guide member pushes the swing lever of the waist support member, causing the waist support member to move to the first position against the biasing force of the torsion spring and be housed inside the device body.

[0009] On the other hand, when the guide member swings from the closed position to the open position, the backing member is biased by the torsion spring and moves to the second position. As a result, the backing member protrudes from inside the device body toward the downstream direction of discharge, and can contact the sheet being conveyed by the first discharge roller from above. The backing member in the second position contacts the sheet being discharged along the face-up discharge path from above, thereby suppressing the curling of the sheet. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Patent No. 5477024 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] However, in the conventional image forming apparatus described above, if the sheet discharged along the face-up discharge path is made of cardboard or the like, the rigidity of the sheet tends to be high. Then, the rigid sheet pushes back against the support member at the second position with a force stronger than the biasing force of the torsion spring, which may cause the support member to detach from the sheet. As a result, this image forming apparatus has the problem that it is difficult to reliably suppress the curling of the sheet discharged along the face-up discharge path.

[0012] The present invention has been made in view of the above-mentioned conventional circumstances, and aims to provide an image forming apparatus that can reliably suppress curling of sheets discharged along the first discharge path. [Means for solving the problem]

[0013] The image forming apparatus of the present invention comprises a housing having an opening, An image forming unit located within the housing, the image forming unit that forms an image on a sheet that passes through it, A conveying unit that transports the sheet that has passed through the image forming unit along a first discharge path that discharges the sheet in the discharge direction with the image-formed surface facing upward, or a second discharge path that guides the sheet upward above the first discharge path for discharge. A re-transport unit that transports a sheet that has been switched back so that the rear end of the sheet being transported along the second discharge path becomes the front end, along a re-transport path branched from the second discharge path, the re-transport unit transports the sheet to the image forming unit so that an image is formed on the side of the sheet opposite to the side on which the image is formed, A cover movable to a closed position which closes the opening, wherein the sheet that has passed through the image forming unit faces the second discharge path, and to an open position which moves downstream and downward in the discharge direction from the closed position to open the opening, wherein the sheet that has passed through the image forming unit faces the first discharge path, and to an open position which supports the sheet being discharged along the first discharge path through the opening, With the cover in the closed position, a flapper in a first position that can be displaced between a first position that guides the sheet that has passed through the image forming unit to the second discharge path, and a second position that guides the sheet that has switched back midway through the second discharge path to the re-transport path, An image forming apparatus comprising, A connecting portion connecting the cover and the flapper, further comprising a connecting portion that moves the flapper from the first position to the second position in conjunction with the movement of the cover from the closed position to the open position, and moves the flapper from the second position to the first position in conjunction with the movement of the cover from the open position to the closed position, The flapper is characterized in that, when in the second position, it protrudes from inside the housing toward the downstream direction in the discharge direction and can contact the sheet being conveyed by the conveying unit from above.

[0014] In the image forming apparatus of the present invention, when the connecting part moves the cover from the closed position to the open position, the flapper moves to the second position in conjunction with the movement of the cover. The flapper then contacts the sheet being discharged along the first discharge path from above, thereby suppressing the curling of the sheet. In other words, the flapper also serves as a discharge guide.

[0015] Here, if the sheet discharged along the first discharge path is made of cardboard or similar material, its rigidity tends to be high. And this highly rigid sheet may try to push back the flapper located at the second position.

[0016] Even in such cases, a large force corresponding to the weight of the cover acts on the flapper through the connecting part, so the flapper is held in the second position with high certainty. As a result, this image forming apparatus can reliably prevent the flapper from escaping from the sheet even if the highly rigid sheet tries to push back against the flapper in the second position.

[0017] Therefore, the image forming apparatus of the present invention can reliably suppress curling of the sheet discharged along the first discharge path. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view of an image forming apparatus according to an embodiment, showing the state where the first and second covers are in the closed position, the third cover is in the retracted position, and the flapper is in the first position. [Figure 2] This is a schematic partial cross-sectional view of an image forming apparatus according to an embodiment, showing the first and second covers in the open position, the third cover in the deployed position, and the flapper in the second position. [Figure 3] This is a rear view of the image forming apparatus of the embodiment, showing the first and second covers in the closed position and the third cover in the retracted position. [Figure 4]A partial perspective view of the image forming apparatus according to the embodiment, showing a state where the first and second covers are in the open position, the third cover is in the deployed position, and the flapper is in the second position. [Figure 5] A schematic partial cross-sectional view of the image forming apparatus according to the embodiment, explaining the operation of the connecting portion that moves the flapper to the second position in conjunction with the movement of the first and second covers to the open position. [Figure 6] A schematic partial cross-sectional view similar to FIG. 5, explaining the operation of the connecting portion that moves the flapper to the first position in conjunction with the movement of the first and second covers to the closed position, showing a state where the flapper is displaced to the first posture by the biasing force of the torsion coil spring. [Figure 7] A schematic partial cross-sectional view similar to FIG. 6, showing a state where the flapper in the first position is displaced to the second posture against the biasing force of the torsion coil spring.

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0020] (Embodiment) As shown in FIG. 1, the image forming apparatus 1 according to the embodiment is an example of a specific aspect of the image forming apparatus of the present invention. The image forming apparatus 1 is a laser printer that forms an image on a sheet SH by an electrophotographic method.

[0021] In FIG. 1, the side of the housing 9 of the image forming apparatus 1 where the manual feed tray 10 is located is defined as the front of the image forming apparatus 1, the side of the housing 9 where the cover 100 is located is defined as the rear of the image forming apparatus 1, and the side of the housing 9 where the discharge tray 9T is located is defined as the upper side of the image forming apparatus 1. And the directions shown in each of the figures after FIG. 2 are displayed corresponding to FIG. 1.

[0022] <Schematic Configuration of Image Forming Apparatus> As shown in Figure 1, the image forming apparatus 1 comprises a housing 9, an image forming unit 3, a sheet tray 9C, a feeding unit 20, a manual feed tray 10, a manual feed unit 25, a pair of post-fixing transport rollers 26, a cover 100, a pair of discharge assist rollers 28, a pair of discharge rollers 29, and a re-transport unit 30. The pair of post-fixing transport rollers 26 is an example of the "transport unit" of the present invention.

[0023] The housing 9 is roughly box-shaped, and the image forming unit 3 is located inside it. The image forming unit 3 is a direct transfer type color electrophotographic system. The image forming unit 3 has a well-known configuration including a process cartridge 4, a transfer belt 6, a scanner unit 8, and a fuser 7, and forms an image on the upward-facing surface of the passing sheet SH.

[0024] The process cartridge 4 is a collection of four cartridges arranged in series in the front-to-back direction, corresponding to four toner colors: black, yellow, magenta, and cyan. The process cartridge 4 has four photoreceptors 5 corresponding to each toner color, as well as a developing roller (not shown), a charger, and a toner storage section. The transfer belt 6 faces each photoreceptor 5 from below.

[0025] The scanner unit 8 includes a laser light source, a polygon mirror, an fθ lens, and a reflector. The scanner unit 8 irradiates each photoreceptor 5 in the process cartridge 4 with a laser beam from above.

[0026] The fuser unit 7 is located behind the process cartridge 4. The fuser unit 7 has a heating roller 7A and a pressure roller 7B. The heating roller 7A is an example of the "heating member" of the present invention. The pressure roller 7B is an example of the "pressure member" of the present invention.

[0027] The nip positions of the heating roller 7A and the pressure roller 7B are located above the transport surface 6A on the transfer belt 6 that faces each photoreceptor 5.

[0028] The fuser unit 7 heats and pressurizes the sheet SH that has passed below the process cartridge 4 using the heating roller 7A and the pressure roller 7B.

[0029] The housing 9 has an output tray 9T on its upper surface. The output tray 9T supports the sheet SH after image formation is complete.

[0030] The housing 9 detachably houses a sheet tray 9C at its bottom. The sheet tray 9C houses sheets SH in a stacked state before images are formed by the image forming unit 3. Sheet SH can be paper, OHP sheets, etc.

[0031] The feeding unit 20 includes a feeding roller 21, a separation roller 22, a separation pad 22A, a first transport roller pair 23, and a second transport roller pair 24, all arranged along the feeding path PF1.

[0032] The feeding path PF1 is a path that starts from the front end of the sheet tray 9C, moves upward and forward, then makes a U-turn, and proceeds backward to reach the image forming unit 3.

[0033] The supply roller 21 sends the sheets SH contained in the sheet tray 9C to the supply path PF1. The separation roller 22 and separation pad 22A separate the sheets SH sent by the supply roller 21 into individual sheets if multiple sheets are stacked on top of each other.

[0034] The first transport roller pair 23 and the second transport roller pair 24 nip the sheets SH, which have been separated one by one by the separation roller 22 and separation pad 22A, and transport them toward the image forming unit 3.

[0035] The housing 9 pivotably supports the manual feed tray 10 on its front side. The manual feed tray 10 is movable between an upright position, as shown by the solid line in Figure 1, which stands upright and forms part of the front of the housing 9, and a manual feed position, as shown by the dashed line in Figure 1, which protrudes forward from the middle of the vertical direction on the front of the housing 9.

[0036] When the manual feed tray 10 is in the manual feed position, it supports the sheet SH that the user intends to feed manually to the image forming unit 3 to form an image. Sheets SH that the manual feed tray 10 can support include paper, OHP sheets, as well as cardboard, envelopes, etc.

[0037] The manual feed unit 25 is located in front of the second transport roller pair 24. The manual feed unit 25 works in cooperation with the second transport roller pair 24 to transport the sheets SH supported on the manual feed tray 10 at the manual feed position toward the image forming unit 3 one by one.

[0038] The post-fixing transport roller pair 26 is located behind the fuser 7. The post-fixing transport roller pair 26 includes a drive roller 26A and a pinch roller 26P. The nip positions of the drive roller 26A and pinch roller 26P are located above the nip positions of the heating roller 7A and pressure roller 7B.

[0039] After fixing, the transport roller pair 26 transports the sheet SH that has passed through the fuser 7 of the image forming unit 3 along the first discharge path P1 shown in Figure 2, or the second discharge path P2 shown in Figure 1.

[0040] As shown in Figure 2, the first discharge path P1 is a path that discharges the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and been transported by the transport roller pair 26 after fixing, in the discharge direction DE1 to a position behind the back of the housing 9, with the side on which the image has been formed facing upwards. The discharge direction DE1 is the direction that moves backward along the front-to-back direction.

[0041] As shown in Figure 1, the second discharge path P2 guides the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and been conveyed by the transport roller pair 26 after fixing, upward from the first discharge path P1, and makes a U-turn so that the surface on which the image is formed faces downward, before being discharged to the discharge tray 9T.

[0042] As shown in Figures 1 to 4, the housing 9 has an opening 9H on its rear surface. The opening 9H is a roughly rectangular opening that opens up most of the upper half of the rear surface of the housing 9.

[0043] As shown in Figure 2, the opening 9H allows the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and been transported by the transport roller pair 26 after fixing, to pass through to a position behind the back of the housing 9.

[0044] As shown in Figures 1 to 4, the cover 100 has a first cover 110 and a second cover 120. The housing 9 supports the first cover 110 and the second cover 120 so that they can swing around the opening / closing axis X100.

[0045] The opening / closing axis X100 extends in the width direction of the housing 9 near the lower edge of the opening 9H. The width direction is perpendicular to the ejection direction DE1 and the vertical direction. The rotation axis of the photoreceptor 5 extends parallel to the width direction.

[0046] The cover 100 is movable between a closed position, which closes the opening 9H, as shown in Figures 1 and 3, and an open position, which opens the opening 9H, as shown in Figures 2 and 4, by the first cover 110 and the second cover 120 each swinging around the opening / closing axis X100.

[0047] As shown in Figure 3, the first cover 110, when in the closed position, has an upper portion that runs along the upper edge of the opening 9H and a pair of lateral portions that run along the side edges located on one and the other in the width direction of the opening 9H.

[0048] Furthermore, the first cover 110 has a notch 110C. The notch 110C is a region of the first cover 110 surrounded by the upper portion and a pair of lateral portions.

[0049] The second cover 120 is located inward in the width direction relative to the first cover 110. When the first cover 110 and the second cover 120 are in the closed position, the second cover 120 fits into the notch 110C of the first cover 110, and together with the first cover 110 closes the opening 9H.

[0050] As shown in Figures 2 and 4, with the first cover 110 and the second cover 120 in the open position, the second cover 120 is located downstream and below the first cover 110 in the discharge direction DE1.

[0051] As shown in Figure 4, in this embodiment, the first cover 110 and the second cover 120 are resin molded products manufactured by injection molding of thermoplastic resin or the like.

[0052] The second cover 120 has a flat cover body 121 and a plurality of ribs 129 that protrude from the cover body 121. The ribs 129 are spaced apart from each other and arranged in the width direction.

[0053] As shown in Figure 1, with the second cover 120 in the closed position, the cover body 121 extends in the vertical and widthwise directions, closing the opening 9H together with the first cover 110. In this state, each rib 129 protrudes forward from the surface of the cover body 121 facing the inside of the housing 9 and extends in the vertical direction. In this state, the leading edge 129A of each rib 129, which is located on the opposite side of the cover body 121 and extends in the vertical direction, is curved such that its middle section is shifted backward relative to the ends located above and below.

[0054] The closed position of the first cover 110 and the second cover 120 is the position where the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and is conveyed by the post-fixing transport roller pair 26, is heading towards the second discharge path P2.

[0055] The leading edge 129A of each rib 129 extends along the second discharge path P2 when the second cover 120 is in the closed position, guiding the sheet SH, which is conveyed by the post-fixing conveyor roller pair 26, along the second discharge path P2. That is, the sheet SH, which is conveyed by the post-fixing conveyor roller pair 26, is guided by each rib 129 of the second cover 120, which changes its orientation so that it faces upward and then forward, and is then discharged onto the discharge tray 9T.

[0056] As shown in Figure 2, the open positions of the first cover 110 and the second cover 120 are the positions in which the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and is conveyed by the post-fixing transport roller pair 26, is heading towards the first discharge path P1.

[0057] When the first cover 110 is in the open position, it allows the sheet SH to pass through the opening 9H along the first discharge path P1 via the notch 110C. When the second cover 120 is in the open position, it supports the sheet SH that is discharged along the opening 9H along the first discharge path P1 with the leading edge 129A of each rib 129. That is, when the second cover 120 is in the open position, each rib 129 protrudes upward and is aligned in the width direction, and the leading edge 129A of each rib 129 is located below the nip point of the post-fixing conveying roller pair 26 and below the flapper 50 which has moved to the second position as described later, and downstream in the discharge direction DE1.

[0058] When a user attempts to form an image on a sheet SH that is difficult to transport along the second discharge path P2, such as rigid cardboard or an envelope, they will select a so-called straight discharge method, where the first cover 110 and the second cover 120 are in the open position, the sheet SH is supported in the manual feed tray 10 at the manual feed position and fed to the image forming unit 3, and the sheet SH that has passed through the image forming unit 3 is discharged along the first discharge path P1.

[0059] As shown in Figures 1 to 4, the second cover 120 has a third cover 130. The third cover 130 is a flat plate member that extends along the outer surface of the cover body 121. The second cover 120 slidably supports the third cover 130 by a pair of slide guides 120G located at one end and the other end in the width direction of the cover body 121.

[0060] The third cover 130 is movable between the storage position shown in Figures 1 and 3 and the deployed position shown in Figures 2 and 4 by reciprocating along the outer surface of the cover body 121 in the radial direction of the opening / closing axis X100.

[0061] As shown in Figures 1 and 3, the third cover 130, when in the retracted position, overlaps the cover body 121 of the second cover 120. On the other hand, as shown in Figures 2 and 4, when in the deployed position, the third cover 130 protrudes rearward from the cover body 121 and supports the sheet SH, which is discharged along the first discharge path P1, together with the second cover 120, which is in the open position.

[0062] The discharge assist roller pair 28 is positioned above the post-fixing transport roller pair 26. The discharge roller pair 29 is positioned in front of the discharge assist roller pair 28 and above the rear end of the discharge tray 9T.

[0063] The discharge assist roller pair 28 and the discharge roller pair 29 are controlled by a control unit (not shown) to rotate in the forward and reverse directions.

[0064] When the discharge assist roller pair 28 and the discharge roller pair 29 are rotating in the forward direction, the discharge assist roller pair 28 nips the sheet SH being transported along the second discharge path P2 and transports it toward the discharge roller pair 29, and the discharge roller pair 29 nips the sheet SH and discharges it toward the discharge tray 9T.

[0065] While the discharge assist roller pair 28 and the discharge roller pair 29 are rotating in the forward direction to discharge the sheet SH to the discharge tray 9T, they are controlled by a control unit (not shown) to switch from forward rotation to reverse rotation, thereby switching back the sheet SH that is being transported along the second discharge path P2 so that its rear end becomes the front end. The discharge assist roller pair 28 and the discharge roller pair 29 then continue to rotate in the reverse direction for a predetermined time to transport the switched-back sheet SH towards the re-transport path P3.

[0066] The re-transport path P3 branches off from the second discharge path P2 and is a path that re-transports the sheet SH, which has been switched back by the reverse rotation of the discharge auxiliary roller pair 28 and the discharge roller pair 29, to the image forming unit 3.

[0067] More specifically, the re-transport path P3 branches off from a position below the pair of discharge assist rollers 28 in the second discharge path P2, extends downward, then proceeds forward above the sheet tray 9C and below the transfer belt 6, and then makes an upward U-turn to merge with the feed path PF1 at a position ahead of the pair of second transport rollers 24.

[0068] The re-transport unit 30 has pairs of re-transport rollers 31, 32, and 33 arranged along the re-transport path P3. The pairs of re-transport rollers 31, 32, and 33 transport the sheet SH that has switched back midway along the second discharge path P2 and entered the re-transport path P3 along the re-transport path P3. The re-transport unit 30 then transports the sheet SH that has switched back to the image forming unit 3 so that an image is formed on the side opposite to the side on which the image was formed.

[0069] <Flapper, connecting part, support part, and torsion coil spring> In the image forming apparatus 1, if a sheet SH being transported along the second discharge path P2 is switched back, and no countermeasures are taken, there is a risk that the switched-back sheet SH may mistakenly proceed toward the fixed-post transport roller pair 26, preventing it from entering the re-transport path P3.

[0070] Furthermore, in the image forming apparatus 1, the nip positions of the heating roller 7A and the pressure roller 7B are located above the transport surface 6A on the transfer belt 6 that faces each photoreceptor 5. The nip positions of the drive roller 26A and the pinch roller 26P are located above the nip positions of the heating roller 7A and the pressure roller 7B.

[0071] Therefore, as shown in Figure 2, when the sheet SH is nipped by the heating roller 7A and pressure roller 7B of the fuser 7 and the drive roller 26A and pinch roller 26P of the post-fixing transport roller pair 26 and discharged along the first discharge path P1, if no countermeasures are taken, there is a risk that the discharged sheet SH will curl upward. This curling is particularly likely to occur if the sheet SH is made of cardboard, envelopes, or other materials that are prone to bending.

[0072] To suppress these problems, the image forming apparatus 1 further includes a flapper 50 shown in Figures 1, 2, and 4 to 7, a connecting part 60 shown in Figures 3 to 7, a support part 70 shown in Figures 4 to 7, and a torsion coil spring 59 shown in Figures 5 to 7.

[0073] As shown in Figures 3 and 4, there is a pair of connecting parts 60 on one side and the other side in the width direction of the housing 9, and they have the same configuration but in a different direction. For this reason, the connecting parts 60 on one side in the width direction will be shown and explained in Figures 5 to 7, and the explanation of the connecting parts 60 on the other side in the width direction will be omitted.

[0074] There is a pair of support parts 70 on one side and the other side in the width direction of the housing 9, and they have the same configuration but in a different direction. Therefore, the support parts 70 located on one side in the width direction are illustrated and explained in Figures 4 to 7, and the explanation of the support parts 70 on the other side in the width direction is omitted.

[0075] There are also pairs of torsion coil springs 59 on one side and the other side in the width direction of the housing 9, and they have the same configuration but in a different direction. Therefore, the torsion coil springs 59 located on one side in the width direction are illustrated and explained in Figures 5 to 7, and the explanation of the torsion coil springs 59 on the other side in the width direction is omitted.

[0076] As shown in Figures 4 and 5, the flapper 50 has a flapper body 51, a pivot shaft 56, and a supported shaft 57. In this embodiment, the flapper 50 is a resin molded product manufactured by injection molding of a thermoplastic resin or the like.

[0077] The pivot shaft 56 and the supported shaft 57 are each located in pairs at one end and the other end in the width direction of the flapper body 51. Since they have the same configuration but in opposite directions, the pivot shaft 56 and the supported shaft 57 located on one side in the width direction are illustrated and explained in Figures 4 to 7, and the pivot shaft 56 and the supported shaft 57 located on the other side in the width direction will not be explained.

[0078] As shown in Figures 4 and 5, the flapper body 51 extends flat in the width direction and has a first surface 50A and a second surface 50B facing opposite directions. The first surface 50A and the second surface 50B are each curved surfaces substantially composed of a plurality of ribs that protrude from the flapper body 51 and are spaced apart from each other and arranged in the width direction.

[0079] The pivot shaft 56 is a cylinder that protrudes outward in the width direction from the side end face in the width direction of the flapper body 51.

[0080] The supported shaft 57 is a cylinder that protrudes outward in the width direction from a position spaced apart from the pivot shaft 56 on the widthwise side end face of the flapper body 51.

[0081] As shown in Figures 3 and 4, the first cover 110 has a pair of connecting pieces 116 on its outer surface. The pair of connecting pieces 116 are located outside the notch 110C in the width direction and on the upper end side of the first cover 110.

[0082] As shown in Figures 4 and 5, the connecting portion 60 is a single link arm that bends into a roughly "L" shape when viewed from the side. As shown in Figures 5 to 7, the connecting piece 116 of the first cover 110 and one end of the connecting portion 60 are connected at the connecting point CP1.

[0083] The other end of the connecting portion 60 is located in front of and below one end of the connecting portion 60, and also in front of the first cover 110. The other end of the connecting portion 60 and the pivot shaft 56 of the flapper 50 are connected at the connection point CP2.

[0084] In other words, the connecting section 60 connects the first cover 110 and the flapper 50.

[0085] As shown in Figures 4 and 5, the support portion 70 is part of a frame member located on one side and the other side in the width direction within the housing 9, and protrudes rearward. The support portion 70 has an elongated hole 70H. The elongated hole 70H extends in the front-rear direction along the discharge direction DE1.

[0086] As shown in Figures 5 to 7, the support portion 70 supports the supported shaft 57 of the flapper 50 so that it can rotate and slide in the front-rear direction by means of an elongated hole 70H.

[0087] The torsion coil spring 59 has a coil portion 59C and one end 59A and the other end 59B extending from the coil portion 59C, respectively.

[0088] The pivot shaft 56 of the flapper 50 is inserted inside the coil section 59C. One end 59A is locked to the flapper body 51 at an intermediate position between the pivot shaft 56 and the supported shaft 57. The other end 59B protrudes upward and backward from the coil section 59C.

[0089] As shown in Figure 5, when the first cover 110 and the second cover 120 are in the open position, there is nothing to lock the other end 59B.

[0090] When the first cover 110 and the second cover 120 move from the open position shown in Figure 5 to the closed position shown in Figure 6, the connecting part 60 rotates downward around the connecting point CP1 in conjunction with the movement of the first cover 110, and the connecting point CP2 between the connecting part 60 and the pivot shaft 56 of the flapper 50 moves upstream and downward in the discharge direction DE1, moving the pivot shaft 56 of the flapper 50 to a position further downward from the supported shaft 57. As a result, the flapper 50 becomes rotatable around the pivot shaft 56 with its first surface 50A facing forward and its second surface 50B facing backward at a position closer to the first cover 110 and the second cover 120 than the first surface 50A.

[0091] At this time, the other end 59B of the torsion coil spring 59 comes into contact with the surface of the second cover 120 facing inward as it moves to the closed position, and is pushed forward. As a result, as shown in Figure 6, the torsion coil spring 59 stores a restoring force, biasing the flapper 50 so that the supported shaft 57 slides forward within the elongated hole 70H.

[0092] In this state, the flapper 50 is pushed by the sheet SH being conveyed by the post-fixing conveying roller pair 26, causing it to rotate against the biasing force of the torsion coil spring 59, as shown in Figure 7, so as to slide the supported shaft 57 backward within the elongated hole 70H.

[0093] The position of the flapper 50 shown in Figures 1, 6, and 7 is the first position.

[0094] The orientation of the flapper 50 shown by the dashed line in Figure 1 and the orientation of the flapper 50 shown in Figure 7 are the first orientations that guide the sheet SH, which has passed through the fuser 7 of the image forming unit 3 and been conveyed by the transport roller pair 26 after fixing, to the second discharge path P2.

[0095] The orientation of the flapper 50 shown by the solid line in Figure 1, and the orientation of the flapper 50 shown in Figure 6, are the second orientations that guide the sheet SH, which has switched back midway through the second discharge path P2, to the re-transport path P3.

[0096] In other words, the flapper 50 is in a first position in which it can be displaced between a first and a second position, with the first cover 110 and the second cover 120 in the closed position.

[0097] The first surface 50A contacts the sheet SH being transported in a first orientation at the first position of the flapper 50. The second surface 50B contacts the sheet SH being transported along the re-transport path P3 in a second orientation at the first position of the flapper 50.

[0098] When the first cover 110 is in the closed position, the connection point CP1 between the connecting portion 60 and the first cover 110 is located above the flapper 50 in the first position.

[0099] When the first cover 110 and the second cover 120 move from the closed position shown in Figure 6 to the open position shown in Figure 5, the connecting portion 60 rotates upward around the connecting point CP1 in conjunction with the movement of the first cover 110, and the connecting point CP2 between the connecting portion 60 and the pivot shaft 56 of the flapper 50 moves downstream and upward in the discharge direction DE1, lifting the pivot shaft 56 of the flapper 50 and pulling it downstream in the discharge direction DE1, and sliding the supported shaft 57 downstream in the discharge direction DE1 within the elongated hole 70H.

[0100] As a result, as shown in Figures 2, 4, and 5, the flapper 50 moves to the second position. In the second position, the flapper 50 has its first surface 50A facing downwards and protruding from inside the housing 9 toward the downstream direction DE1 of discharge. As shown in Figure 2, the first surface 50A of the flapper 50 can contact the sheet SH that is conveyed by the post-fixing conveying roller pair 26 from above.

[0101] Thus, the connecting portion 60 moves the flapper 50 from the first position to the second position in conjunction with the movement of the first cover 110 when the first cover 110 and the second cover 120 move from the closed position to the open position, and moves the flapper 50 from the second position to the first position in conjunction with the movement of the first cover 110 when the first cover 110 and the second cover 120 move from the open position to the closed position.

[0102] <Image Formation Process> The image forming unit 3 forms an image on the sheet SH fed from the sheet tray 9C or the manual feed tray 10 in the following manner. Specifically, the surface of each photoreceptor 5 is uniformly positively charged by a charger as it rotates, and then exposed by high-speed scanning of a laser beam irradiated 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 each photoreceptor 5.

[0103] Next, toner is supplied from the toner storage section to the surface of each photoreceptor 5 in accordance with the electrostatic latent image, and a toner image is formed. Then, as the sheet SH passes through the image forming section 3, the upward-facing side of the sheet SH faces the photoreceptors 5. The toner image carried on the surface of each photoreceptor 5 is then transferred to the upward-facing side of the sheet SH. The fuser 7 fixes the transferred toner image to the sheet SH using the heating roller 7A and the pressure roller 7B.

[0104] As shown in Figure 1, when the first cover 110 and the second cover 120 are in the closed position and an image is formed on only one side of the sheet SH, the post-fixing transport roller pair 26 transports the sheet SH that has passed through the fuser 7 of the image forming unit 3 along the second discharge path P2. At this time, the flapper 50 in the first position is pushed by the leading edge of the transported sheet SH and displaced to the first position, and the first surface 50A comes into contact with the sheet SH. The discharge auxiliary roller pair 28 and the discharge roller pair 29 rotate in the forward direction, nipping the sheet SH and discharging it into the discharge tray 9T.

[0105] When the first cover 110 and the second cover 120 are in the closed position and an image is formed on both sides of the sheet SH, the post-fixing transport roller pair 26 transports the sheet SH, on which an image has been formed on one side, along the second discharge path P2. At this time, the flapper 50 in the first position is pushed by the leading edge of the transported sheet SH and displaced to the first position, and the first surface 50A comes into contact with the sheet SH. The discharge auxiliary roller pair 28 and the discharge roller pair 29 rotate in the forward direction, nipping the sheet SH and transporting it partway along the second discharge path P2.

[0106] The control unit (not shown) reverses the rotation of the discharge assist roller pair 28 and the discharge roller pair 29 at the moment when the rear end of the sheet SH separates from the flapper 50 and the flapper 50 is displaced to the second position, thereby switching back the sheet SH that is being transported along the second discharge path P2 so that its rear end becomes the front end.

[0107] Then, the discharge assist roller pair 28 and the discharge roller pair 29 continue to rotate in the reverse direction for a predetermined time, thereby transporting the switched-back sheet SH toward the re-transport path P3. The re-transport section 30 transports the switched-back sheet SH to the image forming section 3 so that an image is formed on the side opposite to the side where the image was formed. The post-fixing transport roller pair 26, the discharge assist roller pair 28, and the discharge roller pair 29 transport the sheet SH, which has images formed on both sides, along the second discharge path P2 and discharge it into the discharge tray 9T.

[0108] As shown in Figure 2, when the first cover 110 and the second cover 120 are in the open position, the post-fixing transport roller pair 26 transports the sheet SH that has passed through the fuser 7 of the image forming unit 3 along the first discharge path P1 through the opening 9H in the discharge direction DE1. The first cover 110, which is in the open position, allows the sheet SH to pass through the notch 110C. Note that not only sheets SH on which images have been formed by the image forming unit 3, but also, for example, sheets sandwiched between laminate films, may be transported to the fuser 7 without image formation, and the sheets that have been pressed and laminated by the heating roller 7A and pressure roller 7B may be transported along the first discharge path P1 through the opening 9H in the discharge direction DE1.

[0109] In this case, the flapper 50 in the second position protrudes from inside the housing 9 toward the downstream direction DE1 of the discharge direction, and the first surface 50A contacts the sheet SH being conveyed by the conveying roller pair 26 from above, thereby suppressing the upward curling of the sheet SH.

[0110] Even if the sheet SH tries to push back against the flapper 50, the flapper 50 is reliably held in the second position by a large force acting through the connecting part 60, corresponding to the weight of the first cover 110. In particular, when a sheet SH such as a highly rigid envelope, cardboard, or the laminated sheet mentioned above is discharged, the contact between the flapper 50 in the second position and the sheet SH can suppress the curling of the sheet SH.

[0111] Then, when the discharged sheet SH is discharged to a position behind the back of the housing 9, the second cover 120 supports the sheet SH with the leading edge 129A of each rib 129.

[0112] <Effects and Effects> In the image forming apparatus 1 of the embodiment, the connecting portion 60 moves the flapper 50 to the second position in conjunction with the movement of the first cover 110 when the first cover 110 and the second cover 120 move from the closed position shown in Figure 6 to the open position shown in Figure 5.

[0113] As a result, as shown in Figure 2, the flapper 50 prevents the sheet SH from curling upwards by having its first surface 50A contact the sheet SH from above as it is discharged along the first discharge path P1. In other words, the flapper 50 also serves as a discharge guide.

[0114] Here, if the sheet SH discharged along the first discharge path P1 is made of cardboard or similar material, the rigidity of that sheet SH tends to be high. And in some cases, that rigid sheet SH may try to push back the flapper 50 located in the second position.

[0115] Even in such cases, a large force corresponding to the weight of the first cover 110 acts on the flapper 50 via the connecting portion 60, so the flapper 50 is held in the second position with high certainty. As a result, the image forming apparatus 1 can reliably prevent the flapper 50 from escaping from the sheet SH, even if the highly rigid sheet SH tries to push back against the flapper 50 in the second position.

[0116] Therefore, the image forming apparatus 1 of the embodiment can reliably suppress the curling of the sheet SH discharged along the first discharge path P1.

[0117] Furthermore, compared to a configuration in which a discharge guide is provided separately from the flapper 50, and the connecting part 60 connects the cover 100 and the discharge guide, this image forming apparatus 1 can suppress an increase in the number of parts and an increase in size.

[0118] Furthermore, as shown in Figures 4 and 5, the image forming apparatus 1 can improve the design freedom of the movement range when the flapper 50 moves between the first and second positions, the design freedom of the movement range when the first cover 110 moves between the closed and open positions, and the design freedom of the movement range when the second cover 120 moves between the closed and open positions by dividing the cover 100 into two members with different functions, namely the first cover 110 and the second cover 120.

[0119] Furthermore, in this image forming apparatus 1, as shown in Figures 5 to 7, the connecting part 60 is connected to the pivot shaft 56 of the flapper 50, and the support part 70 supports the supported shaft 57 so that it can rotate and slide through the elongated hole 70H. When the first cover 110 is in the closed position shown in Figures 6 and 7, the flapper 50 in the first position rotates around the pivot shaft 56 and the supported shaft 57 slides within the elongated hole 70H, thereby displacing it between a first and a second position. When the first cover 110 moves to the open position shown in Figure 5, the connection point CP2 between the connecting part 60 and the pivot shaft 56 of the flapper 50 moves downstream in the discharge direction DE1, and the supported shaft 57 slides downstream in the discharge direction DE1 within the elongated hole 70H, causing the flapper 50 to move to a second position. With this configuration, the flapper 50 in the first position can be smoothly displaced between a first and a second position.

[0120] Furthermore, in this image forming apparatus 1, as shown in Figure 6, when the first cover 110 is in the closed position, the connection point CP1 between the connecting portion 60 and the first cover 110 is located above the flapper 50 in the first position. This configuration makes it easier for the flapper 50, which is linked to the movement of the first cover 110, to protrude downstream in the discharge direction DE1 when it moves to the second position, to bring its orientation closer to horizontal. This suppresses strong contact between the flapper 50 and the sheet SH being discharged along the first discharge path P1.

[0121] Furthermore, in this image forming apparatus 1, as shown in Figure 1, the flapper 50 has a first surface 50A that contacts the sheet SH being transported in a first orientation at the first position, and a second surface 50B that contacts the sheet SH being transported along the re-transport path P3 in a second orientation at the first position. As shown in Figure 2, the flapper 50 in the second position has its first surface 50A protruding downwards. With this configuration, the flapper 50 in the second position can smoothly contact the sheet SH being discharged along the first discharge path P1 with its first surface 50A.

[0122] Furthermore, as shown in Figures 2 and 4, the image forming apparatus 1 can increase the area supporting the sheet SH discharged along the first discharge path P1 by moving the third cover 130 to the deployed position.

[0123] Furthermore, in this image forming apparatus 1, the second cover 120 supports the third cover 130 so that it can slide between a retracted position and an unfolded position by a slide guide 120G. This configuration allows the user to easily move the third cover 130 between the retracted position and the unfolded position.

[0124] Although the present invention has been described above with reference to examples, it goes without saying that the present invention is not limited to the above examples and can be applied with appropriate modifications without departing from its spirit.

[0125] In the embodiments, the image forming apparatus of the present invention was embodied as image forming apparatus 1, but the present invention is not limited to this configuration. For example, the configuration of the present invention may be applied to the image forming apparatus in a multifunction device equipped with an image reading device above the image forming apparatus.

[0126] In the embodiment, the connecting portion 60 is a single member, but the present invention is not limited to this configuration. For example, the connecting portion may be a configuration in which multiple members are connected.

[0127] In this embodiment, the cover 100 has a first cover 110 and a second cover 120, and the connecting portion 60 moves the flapper 50 in conjunction with the movement of the first cover 110. However, the present invention is not limited to this configuration. For example, the cover may be a single component, and the connecting portion may move the flapper in conjunction with the movement of that cover.

[0128] In this embodiment, the second discharge path P2 is a path that proceeds upward in a U-turn manner and discharges the sheet SH to the discharge tray 9T with the side on which the image is formed facing downwards. However, the present invention is not limited to this configuration. For example, the second discharge path may be a path that proceeds upward in a crank shape and discharges the sheet with the side on which the image is formed facing upwards.

[0129] In this embodiment, the third cover 130 slides between a stored position and an extended position, but the present invention is not limited to this configuration. For example, the third cover may rotate between a stored position and an extended position.

[0130] In this embodiment, a pair of post-fixing transport rollers 26 located downstream of the fuser 7 in the transport direction acts as a transport unit to transport the sheet SH so that it is discharged along the first discharge path P1. However, the present invention is not limited to this configuration. For example, the present invention also includes a configuration in which there is no pair of post-fixing transport rollers 26 between the fuser 7 and the first cover 110 and the second cover 120, and the heating roller 7A and pressure roller 7B of the fuser 7 function as a transport unit, and the sheet SH is transported along the first discharge path P1 by the rotation of the heating roller 7A and pressure roller 7B, and the sheet SH is directly discharged onto the second cover 120 which is in the open position. [Explanation of Symbols]

[0131] 1…Image forming apparatus, 9H…Aperture, 9…Housing 3…Image forming unit, SH…Sheet, DE1…Discharge direction P1…First emission pathway, P2…Second emission pathway 26…Conveying section (conveying roller pair after fixing) P3...Retransport route, 30...Retransport section, 100...Cover 50...Flapper, 60...Connecting section, 110...First cover 120...Second cover, 57...Supported shaft, 56...Rotating shaft, 70H...Slotted hole 70...Support section, CP2...Connection point between the connecting section and the pivot axis of the flapper CP1…Connection point between the connecting section and the first cover 50A...Flapper's first side, 50B...Flapper's second side 130...Third cover, 5...Photoreceptor, 7A...Heating element (heating roller) 7B...Pressure component (pressure roller), 7...Fuser

Claims

1. A housing having an opening, An image forming unit located within the housing, the image forming unit that forms an image on a sheet that passes through it, A conveying unit that transports the sheet that has passed through the image forming unit along a first discharge path that discharges the sheet in the discharge direction with the image-formed surface facing upward, or a second discharge path that guides the sheet upward above the first discharge path before discharge. A re-transport unit that transports a sheet that has been switched back so that the rear end of the sheet being transported along the second discharge path becomes the front end, along a re-transport path branched from the second discharge path, the re-transport unit transports the sheet to the image forming unit so that an image is formed on the side of the sheet opposite to the side on which the image is formed, A cover movable to a closed position which closes the opening, the closed position in which the sheet that has passed through the image forming unit faces the second discharge path, and an open position which moves downstream and downward in the discharge direction from the closed position to open the opening, the open position in which the sheet that has passed through the image forming unit faces the first discharge path, and the open position which supports the sheet that is discharged along the first discharge path through the opening, With the cover in the closed position, a flapper in a first position that can be displaced between a first position that guides the sheet that has passed through the image forming unit to the second discharge path, and a second position that guides the sheet that has switched back midway through the second discharge path to the re-transport path, An image forming apparatus comprising, A connecting portion connecting the cover and the flapper, further comprising a connecting portion that moves the flapper from the first position to the second position in conjunction with the movement of the cover from the closed position to the open position, and moves the flapper from the second position to the first position in conjunction with the movement of the cover from the open position to the closed position, The image forming apparatus is characterized in that, when the flapper is in the second position, it protrudes from inside the housing toward the downstream in the discharge direction and can contact the sheet being conveyed by the conveying unit from above.

2. The cover comprises a first cover connected to the connecting portion, The image forming apparatus according to claim 1, further comprising: a second cover located inside the first cover in a width direction perpendicular to the discharge direction and the vertical direction, the second cover located downstream and below the first cover in the discharge direction when in the open position, and supporting a sheet discharged along the first discharge path.

3. The flapper has a supported shaft that protrudes outward in the width direction, The flapper has a pivot shaft that protrudes outward in the width direction at a position away from the supported shaft when the flapper is in the first position, The support portion further comprises a support portion that rotatably and slidably supports the supported shaft by an elongated hole extending along the discharge direction, The aforementioned connecting portion is connected to the pivot shaft of the flapper, When the first cover is in the closed position, the flapper in the first position rotates around the pivot axis and the supported shaft slides within the elongated hole, thereby displacing it between the first and second positions. The image forming apparatus according to claim 2, wherein when the first cover moves to the open position, the connection point between the connecting portion and the pivot shaft of the flapper moves downstream in the discharge direction, and the supported shaft slides downstream in the discharge direction within the elongated hole, thereby moving the flapper to the second position.

4. The image forming apparatus according to claim 2 or 3, wherein, when the first cover is in the closed position, the connection point between the connecting portion and the first cover is located above the flapper in the first position.

5. The flapper has a first surface that contacts the sheet being transported in the first orientation at the first position, and a second surface that is closer to the cover than the first surface and contacts the sheet being transported along the re-transport path in the second orientation. The image forming apparatus according to claim 2 or 3, wherein the flapper in the second position has the first surface protruding downward.

6. The image forming apparatus according to claim 2 or 3, wherein the second cover has a third cover that is movable between a storage position overlapping the second cover and an unfolded position supporting a sheet discharged along the first discharge path together with the second cover in the open position.

7. The image forming apparatus according to claim 6, wherein the second cover supports the third cover so as to be slidable between the stored position and the deployed position.

8. The image forming unit includes a photoreceptor on which a toner image to be transferred to a sheet is formed, A fuser that fixes the toner image transferred by the heating element and pressurizing element onto a sheet, An image forming apparatus according to any one of claims 1 to 3, having the following features.

Images