Image forming apparatus

Abstract

To provide an image forming device capable of suppressing a sheet conveyance failure while suppressing complication of maintenance work.SOLUTION: An image forming device comprises an image forming section, a device body, a side cover, a sheet storage part, a sheet conveyance path, and a sheet feeding unit. The device body comprises a first side face and a second side face on the opposite side of the first side face. The side cover can be opened in a first direction. The sheet feeding unit comprises a unit body and a roller unit. The roller unit comprises a roller holder and a feed roller. The unit body comprises an opposite wall, an attachment part, a cutout part, and a movable plate supported by the opposite wall so as to be rotatable between a closed position and an open position. The movable plate can be moved to the open position in a state where the side cover is opened and the sheet storage part is detached from the device body. The movable plate disposed at the open position comes in contact with the closed side cover or the sheet storage part attached to the device body to be moved to the closed position.SELECTED DRAWING: Figure 14

Description

Technical Field

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

Background Art

[0002] Conventionally, an image forming apparatus including an apparatus main body, a sheet cassette, a sheet conveyance path, a sheet feeding unit, and a side cover has been known (Patent Document 1). The sheet cassette is a cassette-shaped tray on which sheets can be stacked. The sheet cassette is detachably attached to the apparatus main body. The sheet conveyance path conveys the sheet to the image forming unit of the image forming apparatus. The sheet feeding unit feeds the sheet in the sheet cassette to the sheet conveyance path. The side cover is supported by the apparatus main body and can be opened so as to be separated from the apparatus main body.

[0003] The sheet feeding unit described in Patent Document 1 includes a unit main body and a roller unit. The unit main body has a mounting portion formed on the apparatus main body and a conveyance guide (opposing wall) opposing the side cover. The conveyance guide is provided inside the side cover and is exposed to the outside when the side cover is opened. The conveyance guide is rotatably supported at a maintenance position (open position) and a guide position (closed position).

[0004] The guide position is a position where the conveyance guide guides the sheet conveyed from the sheet cassette to the sheet conveyance path. The maintenance position is a position where the conveyance guide moves closer to the open side cover from the guide position. By moving the conveyance guide to the maintenance position, the periphery of the mounting portion is opened.

[0005] The roller unit includes a roller holder and a feeding roller supported by the roller holder. The roller unit is attached to the mounting portion. The feeding roller contacts the sheet in the sheet cassette and feeds the sheet to the sheet conveyance path.

[0006] Incidentally, when sheets are repeatedly fed through the feeding rollers, the rollers wear down and paper dust adheres to their surfaces. Since the feeding rollers separate the large number of sheets loaded in the sheet cassette one by one and feed them into the sheet transport path, deterioration due to paper feeding is more pronounced than that of transport rollers installed in other locations. Furthermore, a decrease in the transport force of the feeding rollers can lead to malfunctions in the image forming apparatus, such as poor sheet feeding.

[0007] Therefore, in the image forming apparatus described above, the roller unit can be removed from the mounting section and only the feed roller can be replaced in case the feed force of the feed roller decreases or is likely to decrease (for example, after a certain number of sheets have been fed). The roller unit can be attached to and detached from the unit body with the transport guide positioned in the maintenance position.

[0008] Furthermore, jams (paper jams) may occur around the feed rollers due to reasons such as unstable sheet transport by the feed rollers. In this case, the user needs to position the transport guide in a maintenance location and remove the jammed sheets.

[0009] As mentioned above, the transport guide is located inside the side cover. Therefore, users have to open the side cover and move the transport guide to a maintenance position each time they need to replace the feed rollers or clear jams, which is a cumbersome process.

[0010] To address these problems, there is an image forming apparatus configured in which the transport guide automatically moves from the guide position to the maintenance position in conjunction with the opening of the side cover (Patent Document 2). The image forming apparatus in Patent Document 2 can suppress the complexity of tasks such as replacing the feed rollers and jamming. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2003-137453 [Patent Document 2] Japanese Patent Publication No. 2001-19177 [Overview of the project] [Problems that the invention aims to solve]

[0012] Incidentally, the conveyor guide (opposing wall) described above is configured to always be positioned in a maintenance location in conjunction with the side cover, even if the side cover is opened for purposes other than replacing the feed rollers or jamming. Furthermore, even when the purpose is to replace the feed rollers, the entire conveyor guide rotates. As a result, the sheet feeding unit described above is prone to deterioration and damage due to the conveyor guide rotating more than necessary. If the conveyor guide deteriorates, it may lead to sheet conveying problems, such as jamming when feeding sheets onto the sheet conveying path.

[0013] Therefore, in view of the above problems, the present invention aims to provide an image forming apparatus that can suppress sheet transport defects while suppressing the complexity of maintenance work. [Means for solving the problem]

[0014] To achieve the above objective, the first configuration of the present invention is an image forming apparatus comprising an image forming unit, an apparatus body, a side cover, a sheet storage unit, a sheet feeding unit, and a sheet transport path. The image forming unit forms an image on a sheet. The apparatus body has a first side and a second side opposite to the first side. The side cover is provided on the first side of the apparatus body and is openable in a first direction away from the first side. The sheet storage unit is detachable from the second side of the apparatus body and stores a sheet. The sheet transport path is formed inside the apparatus body and transports the sheet to the image forming unit. The sheet feeding unit feeds the sheet stored in the sheet storage unit to the sheet transport path formed inside the apparatus body. The sheet feeding unit comprises a unit body and a roller unit. The roller unit includes a roller holder and a feeding roller rotatably supported by the roller holder and feeding the sheet downstream in the sheet transport direction, and is detachable from the unit body from the first side. The unit body includes an opposing wall facing the side cover, a mounting portion provided on the opposite side of the side cover with the opposing wall in between, to which the roller unit is mounted, a notch formed in the opposing wall that exposes the mounting portion, and a movable plate supported by the opposing wall so as to be rotatable between a closed position that closes the notch and an open position located on the first direction side of the closed position that opens the notch. The movable plate can move to the open position when the side cover is open and the sheet storage portion is removed from the device body. When the movable plate is in the open position, it moves to the closed position by coming into contact with the side cover that is being closed or the sheet storage portion that is being mounted on the device body. [Effects of the Invention]

[0015] According to the first configuration of the present invention, the movement of the movable plate from the open position to the closed position can be linked to the closing operation of the side cover or the installation operation of the sheet storage section, thereby reducing the complexity of maintenance work on the sheet feeding unit. Furthermore, when the side cover is opened, the movable plate does not move in conjunction with the movement of the side cover. Therefore, when the side cover is opened for purposes other than maintenance of the sheet feeding unit or jam removal around the sheet feeding unit, the movable plate does not move. This reduces the opportunities for the movable plate to move, thereby suppressing its deterioration. In addition, when replacing the feeding roller, only the movable plate is moved without moving the opposing wall. Therefore, deterioration of the opposing wall is suppressed. Consequently, deterioration of the sheet feeding unit can be suppressed, and sheet feeding failures can be suppressed.

[0016] Therefore, it is possible to provide an image forming apparatus that can suppress sheet transport defects while suppressing the complexity of maintenance work. [Brief explanation of the drawing]

[0017] [Figure 1] Cross-sectional view showing the schematic configuration of the image forming apparatus 100 of the present invention. [Figure 2] Cross-sectional view of the area around the sheet transport path 14 and the reversal transport path 21 in the image forming apparatus 100 shown in Figure 1. [Figure 3] Cross-sectional view of the image forming apparatus 100 with the side cover 33 in the open position P2 and the sheet cassette 16 removed from the main body 40. [Figure 4] Perspective view showing roller unit 41 and upper transport guide 62 [Figure 5] Perspective view showing the sheet feeding unit 60 with the movable plate 26 positioned at guide position P3. [Figure 6] A perspective view showing the attachment and detachment of the roller unit 41 with the movable plate 26 positioned at the maintenance position P4. [Figure 7] Plan view of the movable plate 26 from the horizontal side of the side cover 33. [Figure 8]Perspective view showing a part of the guide body 22 including the side edge of the maintenance opening 25 and the movable plate 26 [Figure 9] Side cross-sectional view showing the movable plate 26 located at the guide position P3 [Figure 10] Side cross-sectional view showing the movable plate 26 while moving between the guide position P3 and the maintenance position P4 [Figure 11] Side cross-sectional view showing the movable plate 26 arranged at the maintenance position P4 [Figure 12] Side cross-sectional view of the cassette accommodation recess 54 showing the periphery of the movable plate 26 arranged at the maintenance position P4 [Figure 13] Side cross-sectional view of the cassette accommodation recess 54 showing the state where the sheet cassette 16 is inserted to the depth of the cassette accommodation recess 54 from the state of FIG. 12 [Figure 14] Side cross-sectional view of the image forming apparatus showing the state where the side cover 33 is moving from the open position P2 toward the closed position P1 while the movable plate 26 is at the maintenance position P4

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 100 of the present invention. The image forming apparatus 100 according to the present embodiment is a four - tandem type color copier.

[0019] As shown in FIG. 1, inside the main body of the image forming apparatus 100, four image forming units Pa, Pb, Pc, and Pd are provided in order from one side in the horizontal direction (the left side in FIG. 1). These image forming units Pa to Pd are provided corresponding to images of four different colors (magenta, cyan, yellow, and black), and form magenta, cyan, yellow, and black images sequentially through the steps of charging, exposure, development, and transfer, respectively.

[0020] Each image forming section Pa to Pd is equipped with a photoreceptor drum 1a to 1d. Around and below the photoreceptor drums 1a to 1d are charging devices 2a to 2d, an exposure unit 5, developing devices 3a to 3d, and cleaning devices 7a to 7d. The charging devices 2a to 2d charge the photoreceptor drums 1a to 1d. The exposure unit 5 exposes the photoreceptor drums 1a to 1d based on the image data. The developing devices 3a to 3d develop the electrostatic latent image formed on the photoreceptor drums 1a to 1d with toner. The cleaning devices 7a to 7d collect and remove any remaining developer (toner) on the photoreceptor drums 1a to 1d after the toner image has been transferred.

[0021] Adjacent to the image forming sections Pa to Pd, a driven roller 10, a drive roller 11, and an intermediate transfer belt 8 are provided. The driven roller 10 and the drive roller 11 are rotatably supported. The driven roller 10 and the drive roller 11 are arranged parallel to the horizontal direction. The drive roller 11 is connected to a drive source (not shown), such as a motor, and rotates by the driving force of this drive source.

[0022] The intermediate transfer belt 8 is formed from a sheet of dielectric resin. It is preferable that the intermediate transfer belt 8 be a seamless belt. The intermediate transfer belt 8 is stretched over the driven roller 10 and the drive roller 11. The inner surface of the intermediate transfer belt 8 and the outer surface of the drive roller 11 are in contact so that the intermediate transfer belt 8 rotates in accordance with the drive roller 11. The outer surface of the driven roller 10 and the inner surface of the intermediate transfer belt 8 are in contact so that the driven roller 10 rotates in accordance with the intermediate transfer belt 8.

[0023] The intermediate transfer belt 8 is in contact with the photoreceptor drums 1a to 1d. The primary transfer rollers 6a to 6d are positioned so as to face each of the photoreceptor drums 1a to 1d, with the intermediate transfer belt 8 in between. The primary transfer rollers 6a to 6d are rotated at the same linear speed as the photoreceptor drums 1a to 1d and the intermediate transfer belt 8 by a primary transfer drive motor (not shown).

[0024] A secondary transfer roller 9 is positioned opposite the drive roller 11, with the intermediate transfer belt 8 in between. The secondary transfer roller 9 presses against the intermediate transfer belt 8 to form a secondary transfer nip portion N. A cleaning blade 19 is positioned downstream of the secondary transfer nip portion N with respect to the rotation direction of the intermediate transfer belt 8 (counterclockwise as shown in Figure 1). The cleaning blade 19 is in contact with the outer circumferential surface of the intermediate transfer belt 8 and removes toner and other residues remaining on the surface of the intermediate transfer belt 8.

[0025] As the drive roller 11 rotates, the intermediate transfer belt 8 rotates while in contact with the outer surfaces of the photoreceptor drums 1a to 1d. At this time, the primary transfer rollers 6a to 6d apply a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photoreceptor drums 1a to 1d. As a result, the toner image on the photoreceptor drums 1a to 1d is first transferred onto the intermediate transfer belt 8.

[0026] Then, the sheet S is transported to the secondary transfer nip section N at a predetermined timing. The toner image that was primarily transferred to the intermediate transfer belt 8 is then secondarily transferred to the surface of the sheet S. After that, any toner remaining on the surface of the photoreceptor drums 1a to 1d is removed by the cleaning devices 7a to 7d, and a new electrostatic latent image is subsequently formed.

[0027] The sheet S onto which the toner image has been transferred is transported to the fuser 15 via the sheet transport path 14. The secondary transferred toner image is fixed onto the sheet S by the fuser 15. After that, the sheet S is discharged from the image forming apparatus 100. In the case of double-sided printing, the sheet S is diverted to the inversion transport path 21 by a branching section 17 located downstream of the fuser 15. The inversion transport path 21 transports the sheet S again to the secondary transfer nip while inverting its front and back sides. The re-transported sheet S has the toner image secondary transferred to the back side, and the toner image is fixed by the fuser 15. Finally, the sheet S is discharged onto the discharge tray 20 by the discharge roller pair 18.

[0028] Next, the manner in which the sheet S is transported will be described. Figure 2 is a cross-sectional view of the area around the sheet transport path 14 and the inversion transport path 21 in the image forming apparatus 100 shown in Figure 1. As shown in Figures 1 and 2, the image forming apparatus 100 further comprises the apparatus body 40, a sheet cassette 16 (sheet storage section), a sheet transport path 14, a sheet feeding unit 60, and a side cover 33.

[0029] The main body 40 of the device is a part of the main body of the image forming apparatus 100. A cassette housing recess 54 is formed in the lower part of the main body 40. The cassette housing recess 54 is a rectangular space that opens on the second side surface 82 (left side in Figure 1) of the main body 40 and extends horizontally from the edge of the opening toward the interior of the main body 40.

[0030] The sheet cassette 16 is capable of loading sheets S. The sheet cassette 16 is inserted horizontally into the cassette housing recess 54 through the opening of the cassette housing recess 54. The sheet cassette 16 is detachably mounted on the device body 40 at its downstream position relative to the insertion direction.

[0031] The sheet transport path 14 is connected to the cassette housing recess 54. The sheet transport path 14 extends from the cassette housing recess 54 through the resist roller pair 13, the secondary transfer nip section N, the fixing device 15, and the branching section 17 in that order to the discharge roller pair 18.

[0032] The aforementioned inversion transport path 21 is connected to the sheet transport path 14 via a branching section 17. The inversion transport path 21 extends downward along the side of the image forming apparatus 100, curving in a roughly C-shape from the branching section 17, and merges with the sheet transport path 14 at a position upstream of the resist roller pair 13 with respect to the sheet transport direction.

[0033] A pair of resist rollers 13 is positioned between the confluence point of the reverse transport path 21 and the sheet transport path 14 with respect to the sheet transport direction and the secondary transfer nip section N. The pair of resist rollers 13 corrects the skew (diagonal feeding) of the sheet S and adjusts the timing of the sheet S transport to the secondary transfer nip section N.

[0034] As shown in Figures 1 and 2, a sheet loading entrance 44 is formed on the bottom surface of the main body 40 of the device (the surface facing the optional device 101 in the vertical direction). A bypass path 66 is connected to the sheet loading entrance 44. The bypass path 66 extends upward from the opening edge of the sheet loading entrance 44 and is connected to the sheet transport path 14. The bypass path 66 guides the sheet S loaded from the sheet loading entrance 44 to the sheet transport path 14.

[0035] In this embodiment, the image forming apparatus 100 has an optional device 101 positioned below the main body 40 of the apparatus. The optional device 101 is capable of housing sheets S inside. The optional device 101 can be attached to the main body 40 of the apparatus. By attaching the optional device 101 to the main body 40 of the apparatus, in addition to the sheets S stored in the sheet cassette 16, a large quantity of sheets S and sheets S of different sizes can be stored inside the image forming apparatus 100.

[0036] The optional device 101 includes an optional cassette 102 and an optional feeding unit 103. The optional device 101 has a sheet discharge port 46. The sheet discharge port 46 is aligned in a straight line vertically with the sheet inlet 44.

[0037] The optional cassette 102 is capable of loading sheets S. The optional feeding unit 103 is located downstream of the optional cassette 102 with respect to the sheet transport direction and upstream of the sheet discharge port 46. The optional feeding unit 103 discharges the sheets S loaded on the optional cassette 102 from the sheet discharge port 46.

[0038] When the optional device 101 is attached to the main unit 40, the optional feeding unit 103 feeds the sheets S loaded on the optional cassette 102 to the bypass path 66 via the sheet discharge port 46 and the sheet inlet 44. The sheets S transported to the bypass path 66 are guided along the inner wall surface of the bypass path 66 (the second guide surface 51, described later) and then transported to the sheet transport path 14.

[0039] Figure 3 is a cross-sectional view of the image forming apparatus 100 with the side cover 33 in the open position P2 and the sheet cassette 16 removed from the apparatus body 40. As shown in Figures 2 and 3, a transport unit 35 is located inside the side cover 33. When the side cover 33 is in the closed position P1 (see Figure 2), it constitutes the first side surface 81 of the apparatus body 40.

[0040] The side cover 33 is rotatably supported with a pivot point 33a located at the bottom of the device body 40 as its axis of rotation. The transport unit 35 is rotatably supported with a pivot point 33b located at the bottom of the device body 40 as its axis of rotation.

[0041] The transport unit 35 has an engagement mechanism (not shown). The transport unit 35 can engage with the side cover 33 by the engagement mechanism. When the transport unit 35 is not engaged with the side cover 33, it can rotate independently of the side cover 33 around the pivot point 33b. When the transport unit 35 is engaged with the side cover 33, as shown in Figure 3, it rotates together with the side cover 33 around the pivot point 33a. The opening and closing operation of the side cover 33 when the side cover 33 and the transport unit 35 are engaged by the engagement mechanism will be described below.

[0042] The side cover 33 is selectively positioned between a closed position P1 and an open position P2. The closed position P1 is the position in which the side cover 33 constitutes the side of the image forming apparatus 100 (see Figure 2). The open position P2 is the position in which the side cover 33 rotates by a predetermined angle in the circumferential direction of the pivot point 33a from the closed position P1, exposing the interior of the apparatus body 40, including the sheet feeding unit 60 (see Figure 3).

[0043] As shown in Figure 2, with the side cover 33 in the closed position P1, a sheet transport path 14 is formed between the transport unit 35 and the device body 40. A reversal transport path 21 is formed between the transport unit 35 and the side cover 33. In other words, the inner surface of the side cover 33 becomes part of one transport surface of the reversal transport path 21, and the outer surface of the transport unit 35 becomes the other transport surface of the reversal transport path 21.

[0044] As shown in Figure 3, with the side cover 33 in the open position P2, the inner wall surface of the sheet transport path 14 and the inside of the device body 40 are exposed, as described above. In this state, the sheet feeding unit 60, which will be described later, is also exposed, making it possible to perform jam removal and replace the feed roller 42a (feed roller).

[0045] As shown in Figures 2 and 3, a swing guide 45 is provided at the bottom of the conveying unit 35 (see Figure 3). The swing guide 45 is located downstream of the loading entrance 44 with respect to the sheet conveying direction. The swing guide 45 is pivotably supported by the side cover 33 around a pivot point 47. The swing guide 45 swings due to its own weight.

[0046] When the side cover 33 is in the closed position P1, the swing guide 45 forms part of the inner wall surface of the bypass path 66. When the side cover 33 is in the open position P2, the swing guide 45 swings away from the main body of the device 40 (counterclockwise). Therefore, when the side cover 33 is placed in the open position P2, a wide area around the roller unit 41 and the lower transport guide 64 (opposing wall) is exposed.

[0047] Next, the sheet feeding unit 60 will be described in detail. As shown in Figures 2 and 3, the sheet feeding unit 60 is positioned between the sheet cassette 16 and the upstream end of the sheet transport path 14 with respect to the sheet transport direction.

[0048] The sheet feeding unit 60 feeds the sheets S loaded on the sheet cassette 16 to the sheet transport path 14. The sheet feeding unit 60 comprises a unit body 80 and a roller unit 41.

[0049] The unit body 80 includes an upper transport guide 62 (mounting section) and a lower transport guide 64. The upper transport guide 62 is located downstream of the cassette storage recess 54 with respect to the sheet transport direction.

[0050] Figure 4 is a perspective view showing the roller unit 41 and the upper transport guide 62. As shown in Figures 2 to 4, the upper transport guide 62 has an upper guide surface 53 and a feed unit housing recess 37. The upper guide surface 53 is connected to the cassette housing recess 54 and the sheet transport path 14. The upper guide surface 53 is a surface that extends in the sheet transport direction from the cassette housing recess 54 toward the sheet transport path 14.

[0051] The feed unit housing recess 37 is a recess that is recessed from the upper guide surface 53 along its surface direction. The feed unit housing recess 37 is open in the horizontal and vertical directions. The roller unit 41 is housed in the feed unit housing recess 37.

[0052] As shown in Figures 2 to 4, the roller unit 41 comprises a roller holder 63, a pickup roller 43, and a feed roller 42a. The roller unit 41 is inserted into the feeding unit housing recess 37 from the side cover 33 and is detachably attached to the upper transport guide 62 (device body 40). More specifically, the roller holder 63 is inserted into the feeding unit housing recess 37 and is detachably supported by the upper transport guide 62. Here, the configuration of the roller unit 41 will be explained using the example of the state in which it is mounted on the upper transport guide 62.

[0053] The roller holder 63 has a pair of side walls 69 facing each other in the sheet width direction (a direction perpendicular to the sheet conveying direction). The central axes of the feed roller 42a and the pickup roller 43 are rotatably supported at both ends by the pair of side walls 69.

[0054] The pickup roller 43 is located upstream of the feed roller 42a in the sheet conveying direction. When the pickup roller 43 and feed roller 42a wear out due to sheet feeding, the roller unit 41 can be replaced with a new one.

[0055] With the roller unit 41 mounted on the upper transport guide 62, the pickup roller 43 faces the sheet S in the sheet cassette 16 in the vertical direction. When the lift plate (not shown) of the sheet cassette 16 rises, the pickup roller 43 comes into contact with the upper surface of the bundle of sheets S in the sheet cassette 16. In this state, the pickup roller 43 rotates counterclockwise as shown in Figure 1, and the top sheet S in the bundle of sheets S is transported downstream.

[0056] Figure 5 is a perspective view showing the sheet feeding unit 60 with the movable plate 26 positioned in guide position P3 (closed position). Figure 6 is a perspective view showing the attachment and detachment of the roller unit 41 with the movable plate 26 positioned in maintenance position P4 (open position). As shown in Figures 5 and 6, the lower transport guide 64 includes a guide body 22, a movable plate 26, a support mechanism 27, and a positioning mechanism 70.

[0057] Returning to Figures 2 and 3, the guide body 22 is located downstream of the roller unit 41 with respect to the sheet transport direction. The guide body 22 is located at the innermost part of the cassette housing recess 54 (the furthest downstream position along the direction in which the sheet cassette 16 is inserted into the cassette housing recess 54). The guide body 22 constitutes the rear side wall of the cassette housing recess 54.

[0058] A retard roller 42b is rotatably supported on the guide body 22. The retard roller 42b faces the feed roller 42a. The feed roller 42a and the retard roller 42b transport the sheet S fed by the pickup roller 43 to the sheet transport path 14.

[0059] As shown in Figures 5 and 6, the guide body 22 has a maintenance opening 25 (notch).

[0060] The maintenance opening 25 penetrates the guide body 22 horizontally. The maintenance opening 25 is positioned to overlap with the roller unit 41 in the sheet width direction. The size of the maintenance opening 25 is large enough to allow the roller unit 41 to pass through.

[0061] The movable plate 26 is pivotably supported on both side edges of the maintenance opening 25 in the sheet width direction via a support mechanism 27. The movable plate 26 is selectively positioned between a guide position P3 and a maintenance position P4.

[0062] Guide position P3 is the position where the movable plate 26 closes the maintenance opening 25 (see Figure 5). When the movable plate 26 is in guide position P3, it forms part of the inner wall surface (second guide surface 51) of the bypass path 66 together with the guide body 22.

[0063] Maintenance position P4 is the position where the movable plate 26 opens the maintenance opening 25 (see Figure 6). Maintenance position P4 is the position where the movable plate 26 swings horizontally from the guide position P3 to the side further away from the roller unit 41 (closer to the side cover 33).

[0064] Figure 7 is a plan view of the movable plate 26, viewed from the horizontal side of the side cover 33. As shown in Figure 7, the movable plate 26 has insertion holes 38 and arrow ribs 39. The insertion holes 38 are holes that penetrate the movable plate 26 in the horizontal direction (the direction perpendicular to the plane of the paper shown in the figure). Two insertion holes 38 are arranged side by side in the sheet width direction (the left-right direction shown in the figure).

[0065] The arrow rib 39 is a rib that protrudes horizontally from the second guide surface 51, which will be described later. In plan view, the shape of the arrow rib 39 is that of an arrow pointing in the direction of movement (upward in this case) of the movable plate 26 from the guide position P3 to the maintenance position P4. The arrow rib 39 is formed above the insertion hole 38.

[0066] Figure 8 is a perspective view showing a portion of the guide body 22 and the movable plate 26, including the side edge of the maintenance opening 25. Figure 9 is a side cross-sectional view showing the movable plate 26 at the guide position P3. The support mechanism 27 is provided on at least one (here, both) of the side edge of the maintenance opening 25. As shown in Figures 8 and 9, the support mechanism 27 comprises a guide groove 28 and a guide projection 36.

[0067] Guide grooves 28 are formed at both ends of the maintenance opening 25 in the sheet width direction.

[0068] The guide groove 28 has a concave shape that is recessed outward in the sheet width direction (opposite side of the movable plate 26) by the guide wall portion 29. The guide groove 28 is enclosed and defined by the guide wall portion 29. The guide wall portion 29 has a rib shape that protrudes inward in the sheet width direction (towards the movable plate 26).

[0069] As shown in Figure 9, the guide groove 28 is composed of a straight section 30 and an inclined section 31. The straight section 30 extends parallel to the vertical direction. The inclined section 31 is connected to the upper end of the straight section 30. The inclined section 31 extends with an incline that approaches the side cover 33 in the horizontal direction as it extends upward. In other words, the inclined section 31 is connected to the upper end of the straight section 30 with a downward slope from the side cover 33.

[0070] An outer corner portion 32 is formed between the straight portion 30 and the inclined portion 31 of the guide wall portion 29. The outer corner portion 32 has a curved R-shaped surface that passes outside the guide groove 28.

[0071] As shown in Figures 7 to 9, the guide projection 36 is provided on the movable plate 26. The guide projection 36 protrudes along the sheet width direction from the side surface of the movable plate 26 (the surface facing both end edges of the maintenance opening 25) in the sheet width direction.

[0072] In a cross-section perpendicular to the protruding direction of the guide projection 36 (see Figure 9), the maximum external dimension of the guide projection 36 is smaller than the groove width of the guide groove 28. Each edge of the outer surface of the guide projection 36 has a rounded (R) shape. The guide projection 36 is inserted into the guide groove 28. The guide projection 36 is movable while sliding against the guide wall 29 between the straight section 30 and the inclined section 31.

[0073] Figure 10 is a side cross-sectional view showing the movable plate 26 in the process of moving between the guide position P3 and the maintenance position P4. Figure 11 is a side cross-sectional view showing the movable plate 26 in the state where it is positioned at the maintenance position P4.

[0074] As shown in Figure 9, with the movable plate 26 in the guide position P3, the guide projection 36 is located at the lower end of the straight section 30. In this state, the guide projection 36 and the guide wall 29 located at the lower end of the straight section 30 are in contact due to the weight of the movable plate 26.

[0075] In this state, when the movable plate 26 moves upward, the guide projection 36 moves from the lower end to the upper end of the straight section 30, as shown in Figure 10. When the guide projection 36 comes into contact with the outer corner section 48, it slides along the outer corner section 48 and moves toward the inclined section 31. At this time, the movement of the movable plate 26 follows an arc-shaped trajectory that conforms to the R shape of the outer corner section 48.

[0076] As shown in Figure 11, with the movable plate 26 in the maintenance position P4, the guide projection 36 is located on the inclined portion 31. With the movable plate 26 in the maintenance position P4, the center of gravity of the movable plate 26 is located on the side further from the straight portion 30 (towards the side cover 33) than the inclined portion 31 in the horizontal direction. Therefore, with the movable plate 26 in the maintenance position P4, the guide projection 36 and the guide wall portion 29 of the inclined portion 31 come into contact due to the weight of the movable plate 26, and the movable plate 26 is positioned in the horizontal and vertical directions.

[0077] A contact portion 49 is provided at the lower end of the movable plate 26. When the movable plate 26 moves between the guide position P3 and the maintenance position P4, the contact portion 49 moves in an arc shape along the circumferential direction centered on the guide projection 36. As shown in Figures 9 to 11, when the movable plate 26 moves from the maintenance position P4 to the guide position P3, the contact portion 49 rotates along the circumferential direction of the guide projection 36. More specifically, when the guide projection 36 slides against the outer corner portion 32, the contact portion 49 rotates in an arc shape that bulges outwards from the side cover 33 (to the left as shown in Figures 10 to 11).

[0078] Figure 12 is a side cross-sectional view of the cassette housing recess 54 showing the area around the movable plate 26 when it is positioned at maintenance position P4. Figure 13 is a side cross-sectional view of the cassette housing recess 54 showing the state in which the sheet cassette 16 has been inserted all the way to the back of the cassette housing recess 54 from the state in Figure 12.

[0079] As shown in Figure 12, with the movable plate 26 in the maintenance position P4, the contact portion 49 is located inside the cassette housing recess 54. In this state, the contact portion 49 is located further horizontally from the side cover 33 than the first guide surface 50, which will be described later.

[0080] When the sheet cassette 16 is inserted into the cassette housing recess 54 in this state, the contact portion 49 comes into contact with the front end of the sheet cassette 16. When the sheet cassette 16 is moved further towards the back of the cassette housing recess 54 (towards the side cover 33) while the front end of the sheet cassette 16 is in contact with the contact portion 49, the contact portion 49 is pressed by the sheet cassette 16 and moves horizontally towards the side cover 33. As a result of this movement of the contact portion 49, as shown in Figure 13, the guide projection 36 slides in the guide groove 28, and the movable plate 26 moves in an arc shape to the guide position P3.

[0081] The movable plate 26 can be positioned in the maintenance position P4 when the side cover 33 is in the open position P2 and the sheet cassette 16 has been removed from the cassette housing recess 54 (as shown in Figures 3 and 12). In other words, even when the side cover 33 is in the open position P2, the movable plate 26 cannot be positioned in the maintenance position P4 when the sheet cassette 16 is inserted into the cassette housing recess 54 and mounted on the device body 40, as shown in Figure 13.

[0082] As described above, when the movable plate 26 moves from the maintenance position P4 to the guide position P3, the contact portion 49 rotates in an arc shape that bulges outwards from the side cover 33 (to the left in Figure 13). Therefore, when the sheet cassette 16 is mounted on the device body 40 (as shown in Figure 13), the contact portion 49 comes into contact with the sheet cassette 16. As a result, the movable plate 26 is restricted from moving horizontally by the sheet cassette 16. Consequently, the movable plate 26 cannot move to the maintenance position P4.

[0083] Figure 14 is a side cross-sectional view of the image forming apparatus 100, showing the state in which the side cover 33 is moving from the open position P2 to the closed position P1, with the movable plate 26 in the maintenance position P4.

[0084] As shown in Figure 14, when the movable plate 26 is in the maintenance position P4, it comes into contact with the side cover 33, which is moving from the open position P2 towards the closed position P1. As the side cover 33 moves toward the closed position P1 while the movable plate 26 is in contact with it, the movable plate 26 is pressed by the side cover 33 in a direction toward the roller unit 41 in the horizontal direction, and moves toward the guide position P3.

[0085] As shown in Figures 3 and 8, the guide body 22 has a first guide surface 50 and a second guide surface 51. The first guide surface 50 faces the upper guide surface 53. The first guide surface 50 is formed to curve downward from the upper end of the lower transport guide 64 toward the cassette storage recess 54 with respect to the horizontal direction. The first guide surface 50 faces the feed roller 42a. The first guide surface 50 extends from a position inside the cassette storage recess 54 toward the sheet transport path 14 with respect to the sheet transport direction.

[0086] The first guide surface 50 is formed across both the guide body 22 and the movable plate 26. That is, the first guide surface 50 is formed across the entire area of ​​the guide body 22 in the sheet width direction, straddling the movable plate 26. The first guide surface 50 formed on the guide body 22 and the first guide surface 50 formed on the movable plate 26 form the same plane when the movable plate 26 is in the guide position P3.

[0087] The first guide surface 50 and the upper guide surface 53 guide the sheet S, which is conveyed by the feed roller 42a and the retard roller 42b, to the sheet conveying path 14. The sheet S is conveyed to the sheet conveying path 14 while sliding along the first guide surface 50 and the upper guide surface 53.

[0088] The second guide surface 51 is formed on the side of the lower transport guide 64 opposite to the cassette storage recess 54 (the side with the side cover 33) in the horizontal direction. The second guide surface 51 extends vertically from the lower end (contact portion 49) to the upper end of the lower transport guide 64. The second guide surface 51 faces the oscillating guide 45 in the horizontal direction. The second guide surface 51 forms the bypass path 66 described above between itself and the oscillating guide 45.

[0089] As shown in Figure 5, the second guide surface 51 is formed across both the guide body 22 and the movable plate 26. That is, the second guide surface 51 is formed across the movable plate 26 in the sheet width direction. The second guide surface 51 formed on the guide body 22 and the second guide surface 51 formed on the movable plate 26 form the same plane when the movable plate 26 is in the guide position P3. The second guide surface 51 constitutes a part of the inner wall surface of the bypass path 66.

[0090] As shown in Figure 8, the positioning mechanism 70 is provided between the movable plate 26 and the guide body 22. The positioning mechanism 70 is located above the support mechanism 27. The positioning mechanism 70 restricts the movement of the movable plate 26 when it is located at guide position P3 in the horizontal direction. In other words, the movable plate 26, when located at guide position P3, is positioned horizontally by the positioning mechanism 70.

[0091] As shown in Figures 8 to 11, the positioning mechanism 70 is configured to include a positioning projection 71 and a pair of positioning ribs 72. The positioning projection 71 is provided on either the guide body 22 or the movable plate 26. In this embodiment, the positioning projection 71 is formed on both end faces of the movable plate 26 with respect to the sheet width direction. The positioning projection 71 extends parallel to the vertical direction when the movable plate 26 is in the guide position P3.

[0092] The pair of positioning ribs 72 are provided on either the guide body 22 or the other of the movable plate 26. In this embodiment, the pair of positioning ribs 72 are provided on both side edges of the maintenance opening 25 of the guide body 22. More specifically, they are provided on the side edges of the maintenance opening 25 facing the movable plate 26.

[0093] The pair of positioning ribs 72 consist of horizontally opposing positioning ribs 72a and 72b (see Figure 11). Positioning ribs 72a and 72b extend parallel to each other in the vertical direction. The upper end of positioning rib 72b extends upward while being inclined away from positioning rib 72a with respect to the horizontal direction.

[0094] As shown in Figure 11, when the movable plate 26 is in the maintenance position P4, the positioning projection 71 is located further from the positioning rib 72a than from the positioning rib 72b. When the movable plate 26 moves toward the guide position P3 from this position and the guide projection 36 reaches the straight section 30, the positioning projection 71 is located between the positioning ribs 72a and 72b in the horizontal direction, and above the positioning rib 72b.

[0095] As the movable plate 26 moves downward from this state and the guide projection 36 moves toward the lower end, the positioning projection 71 is inserted between the positioning rib 72a and the positioning rib 72b. This causes the positioning projection 71 to engage with the pair of positioning ribs 72. If the movable plate 26 attempts to move horizontally in this state, the positioning projection 71 will come into contact with the pair of positioning ribs 72, restricting the movement of the movable plate 26.

[0096] As described above, the movable plate 26, when in the maintenance position P4, moves from the maintenance position P4 to the guide position P3 by selecting to place the side cover 33 in the closed position P1, or by attaching the sheet cassette 16 to the main body 40 of the device. In other words, the movement of the movable plate 26 from the maintenance position P4 to the guide position P3 can be linked to the closing operation of the side cover 33 or the attachment operation of the sheet cassette 16. This reduces the complexity of maintenance work on the roller unit 41. Furthermore, when the side cover 33 is selected to place in the open position, the movable plate 26 does not move in conjunction with the operation of the side cover 33. Therefore, when the side cover 33 is selected to place in the open position P2 for purposes other than maintenance of the roller unit 41 or jam removal around the roller unit 41, the movable plate 26 does not move. Consequently, the opportunities for the movable plate 26 to move can be reduced, and deterioration of the lower transport guide 64 can be suppressed. Thus, an image forming apparatus 100 can be provided that can suppress sheet transport defects while suppressing the complexity of maintenance work.

[0097] Furthermore, the closing operation of the side cover 33 or the installation operation of the sheet cassette 16 always moves the movable plate 26 to the guide position P3. This prevents the image forming operation from starting without moving the movable plate 26 to the guide position P3.

[0098] Furthermore, as described above, the movable plate 26 moves between the guide position P3 and the maintenance position P4 while the guide projection 36 is guided by the guide groove 28. Therefore, even if the direction of the force acting on the movable plate 26 and the direction of movement of the movable plate 26 do not perfectly coincide, it becomes easier for the plate to move between the guide position P3 and the maintenance position P4. Consequently, the user can easily move the movable plate 26.

[0099] As mentioned above, the inclined section 31 slopes downward from the side cover 33 and connects to the upper end of the straight section 30. Therefore, when the side cover 33 comes into contact with the movable plate 26 during the closing operation, and the movable plate 26 is pressed by the side cover 33, the guide projection 36 is guided down the inclination of the inclined section 31 to the straight section 30. This makes it easier for the movable plate 26, which is in the maintenance position P4, to move to the guide position P3.

[0100] Furthermore, as described above, an outer corner portion 32 is formed between the straight portion 30 and the inclined portion 31. As a result, when the user lifts the movable plate 26 vertically, the guide projection 36 slides along the outer corner portion 32 and is guided to the inclined portion 31. Therefore, the movable plate 26 can be moved from the guide position P3 to the maintenance position P4 without changing the direction of the force applied by the user to the movable plate 26.

[0101] Furthermore, as mentioned above, each edge portion of the outer surface of the guide projection 36 is given an R-chamfer shape. Therefore, when the guide projection 36 slides against the outer corner portion 32 and moves between the straight portion 30 and the inclined portion 31, the guide projection 36 slides more easily.

[0102] Furthermore, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. For example, the image forming apparatus of the above embodiment employs a configuration that includes a reversing transport path 21, but is not limited thereto. That is, a configuration in which a reversing transport path 21 is not formed between the side cover 33 and the transport unit 35 can also be adopted.

[0103] Furthermore, although the movable plate 26 is shown to contact the swing guide 45 of the side cover 33 (see Figure 14), it is also possible to adopt a configuration in which it contacts a part of the side cover 33 other than the swing guide 45. [Industrial applicability]

[0104] The present invention can be used in image forming apparatuses such as copiers, printers, facsimile machines, and their combined devices. By using the present invention, it is possible to provide an image forming apparatus that can suppress sheet transport defects while suppressing the complexity of maintenance work. [Explanation of symbols]

[0105] 14 Sheet transport path 16. Seat cassette (seat storage compartment) 25 Maintenance opening (opening) 26 Movable plate 28 Guide grooves 30 Straight section 31 Slope 33 Side cover 36 Guide projections 40 Main unit of the device 41 Roller Unit 42a Feed roller (feeding roller) 44 Loading entrance 49 Contact area 50 First guide surface 51 Second guide surface 54 Cassette storage recess 60-sheet feeding unit 62 Upper transport guide (mounting part) 63 Roller holder 64. Lower transport guide (opposite wall) 66 Bypass Route 71 Positioning protrusion 72 Positioning Ribs 80 Unit Body 81 First aspect 82 Second aspect 100 Image forming apparatus 101 Optional device P3 Guide position (closed position) P4 Maintenance position (open position) Pa~Pd Image Forming Unit S Seat

Claims

1. An image forming unit that forms an image on a sheet, The apparatus body has a first side surface and a second side surface opposite to the first side surface, A side cover provided on the first side surface of the main body of the device, which can be opened in a first direction away from the first side surface, A seat storage section, which is detachable from the second side of the main body of the device and stores the seat, A sheet transport path formed inside the main body of the apparatus for transporting the sheet to the image forming unit, A sheet feeding unit that feeds the sheet stored in the sheet storage section to the sheet transport path, Equipped with, The aforementioned sheet feeding unit is The main unit and A roller unit comprising a roller holder and a feed roller rotatably supported by the roller holder for feeding the sheet downstream in the sheet transport direction, the roller unit being detachable from the unit body from the first side, It has, The unit body is, The side cover and the opposing wall, A mounting portion is provided on the side opposite to the side cover, with the aforementioned opposing wall in between, and the roller unit is mounted therein. A notch formed in the opposing wall that exposes the mounting portion, It has a movable plate supported by the opposing wall so as to be rotatable between a closed position that closes the notch and an open position that is located on the first direction side of the closed position and opens the notch, The movable plate is movable to the open position when the side cover is open and the seat storage section is detached from the main body of the device. The image forming apparatus is characterized in that the movable plate positioned in the open position comes into contact with the closed side cover or the sheet storage section attached to the main body of the apparatus and moves to the closed position.

2. The opposing wall or the movable plate has a guide groove recessed in the sheet width direction perpendicular to the sheet transport direction, and the other of the opposing wall and the movable plate has a guide projection that protrudes in the sheet width direction and is inserted into the guide groove, The image forming apparatus according to claim 1, characterized in that the movable plate is guided to the closed position and the open position by the guide projection sliding along the guide groove.

3. The guide groove is configured to include a straight section extending in the vertical direction and an inclined section connected to the upper part of the straight section, which extends inclined from the straight section toward the side cover. The guide projection is located on the straight section when the movable plate is in the closed position, and on the inclined section when the movable plate is in the open position. The side cover comes into contact with the movable plate in the open position at a predetermined position during the opening process. The image forming apparatus according to claim 2, characterized in that when the side cover is closed in the direction opposite to the first direction while the side cover and the movable plate are in contact, the side cover presses against the movable plate, causing the guide projection to move from the inclined portion to the straight portion, and the movable plate to be positioned in the closed position.

4. The unit body has a pair of positioning ribs provided on one of the opposing wall or the movable plate, which protrude in the direction of the sheet width, and a positioning projection provided on the other of the opposing wall and the movable plate, which is capable of engaging with the pair of positioning ribs. With the guide projection in the inclined portion, the positioning projection is positioned above the pair of positioning ribs. The image forming apparatus according to claim 3, characterized in that the positioning projection engages with the pair of positioning ribs while the guide projection is in the straight section, and the movable plate is positioned in the closed position.

5. The sheet storage section is detachably attached to the main body of the device at a position upstream of the sheet transport path with respect to the sheet transport direction. The image forming apparatus according to any one of claims 1 to 4, characterized in that the movable plate positioned in the open position moves to the closed position by contact with the sheet storage section mounted on the main body of the apparatus.

6. The main body of the device has a recessed area on the second side that opens and extends horizontally, and is capable of accommodating the sheet storage section. The seat storage section is inserted into the storage recess in the horizontal direction and mounted on the main body of the device. The image forming apparatus according to claim 5, wherein the movable plate has a contact portion that contacts the sheet storage portion in the storage recess when the movable plate is in the open position, and the sheet storage portion moves from the open position to the closed position by pressing the contact portion.

7. The main body of the device has an entrance into which the sheet, which is supplied from an optional device connected below, is brought in. The opposing wall has a first guide surface that guides the sheet being fed from the sheet storage section, and a second guide surface that forms a bypass path between itself and the side cover that guides the sheet being brought in from the entrance to the sheet transport path. The image forming apparatus according to any one of claims 1 to 6, characterized in that the movable plate constitutes a part of the first guide surface and a part of the second guide surface when in the closed position.

Images