Media guide device, image forming device, image reading device, and post-processing device

Abstract

To provide a medium guide device capable of suppressing an occurrence of collision noise caused by bouncing up of a rear end of a medium while ensuring smooth conveyance of the medium on a curved path.SOLUTION: A medium guide device 35 includes: an upstream roller pair 42 and a downstream roller pair 43 provided in a curved path 6A; a first rib 44 protruding from / withdrawing to outside in a radial direction of the curved path 6A on an upstream side of an apex portion 6T; a second rib 45 protruding from / withdrawing to inside in the radial direction of the curved path 6A on a downstream side of the apex portion 6T; and an interlocking part 46 interlocking the first rib 44 with the second rib 45, wherein when paper P being conveyed by the upstream roller pair 42 is in a first conveyance state S1 where it is away from the downstream roller pair 43, the interlocking part 46 withdraws the first rib 44 and protrudes the second rib 45, and when the paper P is in a second conveyance state where the paper P is conveyed by the downstream roller pair 43, the interlocking part 46 protrudes the first rib 44 and withdraws the second rib 45.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a media guide device that guides a transported medium, an image forming apparatus, an image reading apparatus, and a post-processing apparatus. [Background technology]

[0002] For example, the image forming apparatus described in Patent Document 1 was provided with a paper guide device that guides paper transported along a paper transport path. This paper guide device included a guide roller that contacts the transport roller and rotates synchronously with it, and a movable rib that is supported by the guide roller via a floating shaft. When the diameter of the transport roller increases or decreases, the guide roller and the movable rib move in and out of the paper transport path, maintaining the movable rib in an appropriate position relative to the nip between the transport roller and the guide roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-345746 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider a configuration in which roller pairs are provided on the upstream and downstream sides of a curved conveyance path (curved path). The paper is conveyed while being nipped between the upstream roller pair (nip conveyance), and is conveyed while curving along the outer diameter surface of the curved path (hereinafter referred to as the "first state"). As conveyance progresses, the paper continues to be nipped by the upstream roller pair and begins to be nipped by the downstream roller pair. The paper is then pulled radially inward from the outer diameter surface of the curved path and begins to be conveyed along the inner diameter surface (hereinafter referred to as the "second state (early stage)"). As conveyance continues, the trailing edge of the paper passes through the upstream roller pair (nip conveyance ends) and is nipped by the downstream roller pair (hereinafter referred to as the "second state (late stage)"). The stiffness of the curved paper causes the trailing edge of the paper to bounce outward in the radial direction of the curved path. The trailing edge of the paper then slams against the outer diameter surface of the curved path, generating a collision noise.

[0005] In the first state, it is preferable that the upstream side of the curved path is a wide path, and that there is a rib on the downstream side of the curved path that presses the paper from the inside in the radial direction. This ensures smooth paper transport without impeding the transport of the paper along the outer diameter surface of the curved path. In contrast, in the second state (early stage, late stage), it is preferable that the downstream side of the curved path is a wide path, and that there is a rib on the upstream side of the curved path that presses the paper from the outside in the radial direction. This reduces the generation of impact noise caused by the trailing edge of the paper bouncing up.

[0006] However, the technology described in Patent Document 1 keeps the position of the movable rib relative to the nip constant regardless of the diameter of the transport roller, so even if the technology described in Patent Document 1 is applied to a curved path, it is not possible to suppress the generation of collision noise caused by the rear end of the paper bouncing up while ensuring smooth transport of the paper in both the first and second states.

[0007] Taking the above circumstances into consideration, the present invention provides a media guide device, an image forming device, an image reading device, and a post-processing device that can ensure smooth transport of media in a curved path while suppressing the generation of collision noise caused by the rear end of the media bouncing up. [Means for solving the problem]

[0008] The medium guiding device according to the present invention includes a conveying path including a curved path for conveying a medium while curving the medium, a pair of upstream rollers that are provided upstream of an apex of the curved path in a conveying direction of the medium and that convey the medium by rotating while sandwiching the medium; a pair of downstream rollers that are provided downstream of the apex in the conveying direction of the medium in the conveying path and that convey the medium by rotating while sandwiching the medium; a first rib that is provided downstream of the upstream roller pair in the conveying direction and upstream of the apex in the conveying direction so as to be able to appear and disappear into the curved path from the radial outside of the curved path, and that contacts the medium while protruding into the curved path; and a pair of downstream rollers that are provided upstream of the downstream roller pair in the conveying direction and that contact the medium by sandwiching the medium. a second rib that is arranged downstream in the transport direction from the radially inner side of the curved path and that contacts the medium while protruding into the curved path, and an interlocking portion that interlocks the first rib and the second rib to make them appear and disappear into the curved path, wherein when the medium is in a first transport state in which it is being transported while being sandwiched between the upstream roller pair and is separated from the downstream roller pair, the interlocking portion retracts the first rib from the curved path and makes the second rib protrude into the curved path, and when the medium is in a second transport state in which it is being transported while being sandwiched between the downstream roller pair, the interlocking portion protrudes the first rib into the curved path and makes the second rib retract from the curved path.

[0009] In this case, the interlocking portion has a first link portion attached to the first rib and rotatable around a first axis, a second link portion attached to the second rib and rotatable around a second axis and rotatably and slidably connected to the first link portion, and a biasing member that directly or indirectly biases the first rib or the second rib, and in the first conveying state, the biasing force of the biasing member rotates the first link portion and the second link portion so as to retract the first rib from the curved path and protrude the second rib into the curved path, and in the second conveying state, the second rib is pressed by the medium being conveyed, causing the second link portion to rotate and retract from the curved path against the biasing force of the biasing member, and the first link portion slides relative to the second link portion to protrude the first rib into the curved path.

[0010] In another case, the interlocking unit may have a drive unit that causes the first rib to appear and disappear into the curved path, a detection unit that detects the second rib that has retracted from the curved path, and a biasing member that biases the second rib to protrude into the curved path, and in the first conveying state, the drive unit causes the first rib to retract from the curved path, and the second rib is biased by the biasing member to protrude into the curved path, and in the second conveying state, the second rib is pressed by the medium being conveyed and retracts from the curved path against the biasing force of the biasing member, and based on the detection unit detecting the retracted second rib, the drive unit may cause the first rib to protrude into the curved path.

[0011] In other cases, the interlocking unit may have a first drive unit that moves the first rib in and out of the curved path, a second drive unit that moves the second rib in and out of the curved path, and a detection unit that detects that the downstream roller pair is transporting the medium, and when in the first transport state, the first drive unit retracts the first rib from the curved path and the second drive unit protrudes the second rib into the curved path, and when in the second transport state, based on the detection unit detecting the transport of the medium by the downstream roller pair, the first drive unit protrudes the first rib into the curved path and the second drive unit retracts the second rib from the curved path.

[0012] In these cases, the first rib and the second rib may be provided so as to be rotatable about an axis while contacting the medium.

[0013] An image forming apparatus according to the present invention includes any one of the above-described medium guide devices.

[0014] An image reading device according to the present invention includes any one of the above-described medium guide devices.

[0015] A post-processing device according to the present invention includes any one of the above-described media guide devices. [Effects of the Invention]

[0016] According to the present invention, it is possible to suppress the occurrence of collision noise caused by the trailing edge of the medium bouncing up while ensuring smooth transport of the medium along a curved path. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic view (front view) showing the internal structure of a copying machine according to an embodiment of the present invention. [Figure 2] 1 is a front view showing a media guide device according to a first embodiment of the present invention. [Figure 3] 1 is a front view showing a medium guiding device (first conveying state) according to a first embodiment of the present invention. [Figure 4]1 is a front view showing a medium guiding device (second conveying state (early stage)) according to a first embodiment of the present invention. FIG. [Figure 5] 1 is a front view showing the medium guiding device (second conveying state (later stage)) according to the first embodiment of the present invention. FIG. [Figure 6] FIG. 10 is a front view showing a medium guiding device (first conveying state) according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a front view showing a medium guiding device (second conveying state) according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a front view showing a medium guiding device (first conveying state) according to a third embodiment of the present invention. [Figure 9] FIG. 10 is a front view showing a medium guiding device (second conveying state) according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic view (front view) showing the internal structure of a copying machine according to a first modified example of the first to third embodiments of the present invention. [Figure 11] FIG. 10 is a schematic view (front view) showing the internal structure of a copying machine (including a post-processing device) according to a second modified example of the first to third embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that Fr, Rr, L, R, U, and D shown in the drawings indicate front, rear, left, right, top, and bottom. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention.

[0019] [Multifunction device] The multifunction device 1 will be described with reference to Fig. 1. Fig. 1 is a schematic diagram (front view) showing the internal structure of the multifunction device 1.

[0020] The multifunction machine 1 includes an image forming device 1A that forms an image on a sheet P (medium) by electrophotography, and an image reading device 1B that optically reads an image of an original and converts it into electronic data.

[0021] [Image forming equipment] The image forming apparatus 1A has an apparatus main body 2 having a substantially rectangular parallelepiped appearance. A paper feed cassette 3 for storing paper P is detachably provided at the bottom of the apparatus main body 2, and a paper output tray 4 is provided on the top surface of the apparatus main body 2. Note that the paper P, which is an example of a medium, is not limited to paper, and may be any material that can be elastically bent, such as a resin sheet (film). In addition, in the description of the image forming apparatus 1A, the direction in which the paper P is transported is referred to as the "transport direction," and terms such as "upstream" and "downstream" and similar terms refer to "upstream" and "downstream" in the transport direction and similar concepts.

[0022] The image forming apparatus 1A includes a toner container 10, a photosensitive drum 11, a charging device 12, a developing device 13, a transfer roller 14, an optical scanning device 15, and a fixing device 16. The toner container 10 is located in the upper left portion of the apparatus main body 2 and contains, for example, black toner (developer). The photosensitive drum 11 is located in the middle of a first transport path 5 extending from a paper feed cassette 3 to a paper output tray 4 and is driven to rotate around its axis by a motor (not shown). The charging device 12, the developing device 13, and the transfer roller 14 are arranged around the photosensitive drum 11 in the order of the image formation process. The transfer roller 14 contacts the photosensitive drum 11 from below to form a transfer nip. The optical scanning device 15 is located above the photosensitive drum 11. The fixing device 16 is located downstream of the first transport path 5.

[0023] The upstream side of the first transport path 5 is curved in a substantially U-shape, and a pair of paper feed rollers 40 is provided at the upstream end of the curved portion to feed paper P stored in the paper feed cassette 3 into the first transport path 5. A pair of transport rollers 41 is provided at the downstream end of the curved portion of the first transport path 5, and a pair of registration rollers 43 is provided downstream of the pair of transport rollers 41. The pair of registration rollers 43 temporarily holds back the paper P being transported to correct any inclination of the paper P (skew correction). Also provided inside the device main body 2 is a second transport path 6 that branches off from the downstream side of the first transport path 5 and merges with the upstream side of the first transport path 5. The second transport path 6 is provided with multiple pairs of transport rollers 42 for transporting paper P.

[0024] [Image formation processing] The operation of the image forming apparatus 1A will be described below. A control device (not shown) that controls the multifunction device 1 performs image forming processing as follows, based on image data input from an external terminal, for example.

[0025] The charging device 12 charges the surface of the photosensitive drum 11, and the optical scanning device 15 emits scanning light based on image data to form an electrostatic latent image on the surface of the photosensitive drum 11. The developing device 13 develops a toner image on the surface of the photosensitive drum 11 using toner supplied from the toner container 10. The paper feed roller pair 40 sends paper P one sheet at a time from the paper feed cassette 3 to the first transport path 5. The paper P is transported along the first transport path 5, skew-corrected by the registration roller pair 43, and enters the transfer nip. The transfer roller 14 transfers the toner image on the photosensitive drum 11 to the paper P as it passes through the transfer nip, and the fixing device 16 thermally fixes the toner image to the paper P. In the case of single-sided printing, the paper P is discharged to the paper output tray 4.

[0026] In the case of double-sided printing, the paper P is switched back at the downstream end of the first transport path 5 and sent to the second transport path 6, and is then transported by the transport roller pair 42 and returned to the first transport path 5. After that, an image is formed on the back side of the paper P through the same process as above, and the double-sided printed paper P is discharged to the paper output tray 4.

[0027] [Image reader] The image reading device 1B includes a reading unit 20 and a document transport device 21. The reading unit 20 is attached to the top surface of the device body 2, and is arranged above the paper discharge tray 4 with a paper discharge space therebetween. The document transport device 21 is attached to the top surface of the reading unit 20.

[0028] <Reading unit> The reading unit 20 has an optical scanning unit 22, a reflection unit 23, and an image sensor 24. The optical scanning unit 22 irradiates light onto a document placed on a contact glass 25A or a platen glass 25B. The reflection unit 23 reflects the light reflected by the document towards the image sensor 24. When reading a document placed on the platen glass 25B, the optical scanning unit 22 and the reflection unit 23 move so that the optical path length from the document to the image sensor 24 remains constant. The image sensor 24 photoelectrically converts the input light.

[0029] <Document transport device> The document transport device 21 has a document pressing unit 26, a supply tray 27, a discharge tray 28, and a transport unit 29. In the description of the image reading device 1B, the direction in which the document is transported is referred to as the "transport direction," and terms such as "upstream," "downstream," and similar terms refer to "upstream" and "downstream" in the transport direction and similar concepts.

[0030] Document pressing unit 26 is attached to the rear of the upper surface of reading unit 20 via a hinge (not shown) so as to be rotatable (openable and closable). Supply tray 27 extends obliquely upward to the right from transport unit 29, and discharge tray 28 is provided on the upper surface of document pressing unit 26. Supply tray 27 is located at a distance above discharge tray 28.

[0031] Inside the transport section 29, a document transport path 30 is formed, which is curved in a substantially U-shape so as to connect the supply tray 27 to the discharge tray 28. At the upstream end of the document transport path 30, a document feed section 31 is provided which separates the documents loaded on the supply tray 27 one by one and feeds them out to the document transport path 30. A plurality of document transport roller pairs 32 are provided in the middle section of the document transport path 30 (between the document feed section 31 and the contact glass 25A), and a document discharge roller pair 33 is provided at the downstream end of the document transport path 30.

[0032] [Image reading processing] The operation of image reading device 1B will be described. When documents are set on supply tray 27 with document holder 26 closed, the control device executes image reading processing as follows. Note that although the documents loaded on supply tray 27 are sheet-shaped, the documents loaded on platen glass 25B are not limited to sheet-shaped documents and may be booklets, cards, etc.

[0033] The document feed section 31 sends out documents set in the supply tray 27 to the document transport path 30. The documents are transported onto the contact glass 25A by a document transport roller pair 32. The optical scanning unit 22 irradiates light onto the documents passing over the contact glass 25A, and the light reflected by the documents is input to the image sensor 24 and converted into an electrical signal. This reads the image of the documents as image data. The document discharge roller pair 33 sends out the documents that have passed over the contact glass 25A to the discharge tray 28.

[0034] Next, when the document holder 26 is opened and a document is placed on the platen glass 25B, the control device executes the image reading process as follows: The optical scanning unit 22 moves to the right and irradiates the document on the platen glass 25B with light. The light reflected from the document is input to the image sensor 24 and converted into an electrical signal, and the image of the document is read as image data.

[0035] The image data read as described above is stored in the storage unit of the control device, and the control device executes the image formation process (printing) as already explained. Note that the image data may also be saved in an external terminal without being printed.

[0036] Incidentally, it is preferable that the multifunction peripheral 1 be miniaturized in consideration of installation in a limited space such as an office. For this reason, in a miniaturized image forming apparatus 1A, the transport paths 5 and 6 for transporting the paper P are often formed in a serpentine shape (see FIG. 1). As a specific example, a curved path 6A for transporting the paper P while curving is formed downstream of the second transport path 6 (including the junction with the first transport path 5). The transport roller pair 42 located at the most downstream of the plurality of transport roller pairs 42 is provided upstream of the curved path 6A (or may be at the end of the straight portion of the second transport path 6), and the registration roller pair 43 is provided downstream of the curved path 6A (or may be in the straight portion of the first transport path 5). The curved path 6A refers to the range (e.g., the range indicated by the two-dot chain line in FIG. 2) in which the paper P is transported while curving downstream of the second transport path 6 (including a part of the first transport path 5). Furthermore, the curved path 6A may be an arc-shaped path, a broken line path in which a plurality of straight paths are connected while bending finely, or a combination of these, as long as the paper P (medium) can be conveyed while being curved. Furthermore, in the description of this specification, the conveying roller pair 42 will be referred to as the upstream roller pair 42, and the registration roller pair 43 will be referred to as the downstream roller pair 43.

[0037] The upstream roller pair 42 and the downstream roller pair 43 rotate while nipping the paper sheet P to transport the paper sheet P (hereinafter, also referred to as "nip transport"). Note that in each roller pair 42, 43, one roller is driven by a motor or the like and the other roller is driven, but this is not limited to this, and both rollers may be driven. In addition, in the description of this specification, a state in which the paper sheet P is nipped and transported by the upstream roller pair 42 and separated from the downstream roller pair 43 (not nipped and transported by the downstream roller pair 43) is referred to as a first transport state S1 (see FIG. 3). On the other hand, a state in which the paper sheet P is nipped and transported by the downstream roller pair 43, regardless of whether it is nipped and transported by the upstream roller pair 42, is referred to as a second transport state S2 (see FIGS. 4 and 5).

[0038] In the first transport state S1, the paper sheet P is transported while curving along the radially outer surface (outer diameter surface 6B) of the curved path 6A due to its own stiffness (see FIG. 3). Next, when the paper sheet P starts to change from the first transport state S1 to the second transport state S2 (early stage of the second transport state S2), that is, when the paper sheet P continues to be nipped and transported by the upstream roller pair 42 and also starts to be nipped and transported by the downstream roller pair 43, the paper sheet P is subjected to a transport force by the downstream roller pair 43 and is pulled radially inward from the outer diameter surface 6B of the curved path 6A, and starts to be transported along the inner diameter surface 6C of the curved path 6A (see FIG. 4). As the transport of the paper sheet P continues, the rear end of the paper sheet P passes through the upstream roller pair 42 (the nip transport by the upstream roller pair 42 ends) and the paper sheet P is nipped and transported by the downstream roller pair 43 (later stage of the second transport state S2), the stiffness (restoring force) of the paper sheet P curved along the inner diameter surface 6C causes the rear end of the paper sheet P to bounce up from the inner diameter side to the outer diameter side of the curved path 6A (see FIG. 5). Then, the rear end of the paper sheet P hits the outer diameter surface 6B of the curved path 6A, generating a collision sound.

[0039] In the first transport state S1, it is preferable that the upstream side of the curved path 6A is a wide path, and that the sheet P is pressed from the radially inner side on the downstream side of the curved path 6A. This makes it possible to ensure smooth transport of the sheet P without impeding the transport of the sheet P along the outer diameter surface 6B of the curved path 6A. In contrast, in the second transport state S2, it is preferable that the downstream side of the curved path 6A is a wide path, and that the sheet P is pressed from the radially outer side on the upstream side of the curved path 6A. This makes it possible to suppress the generation of collision noise caused by the rear end of the sheet P bouncing up. Therefore, the image forming apparatus 1A is provided with a media guiding device 35 that suppresses the generation of collision noise caused by the rear end of the sheet P bouncing up while ensuring smooth transport of the sheet P along the curved path 6A.

[0040] [Media guide device] The medium guiding device 35 according to the first embodiment will be described with reference to Figures 2 and 3. Figure 2 is a front view showing the medium guiding device 35. Figure 3 is a front view showing the medium guiding device 35 (first transport state S1).

[0041] As shown in FIG. 2, the medium guiding device 35 includes an upstream roller pair 42, a downstream roller pair 43, a first rib 44, a second rib 45, and an interlocking portion 46.

[0042] <Upstream roller pair, downstream roller pair> As shown in FIG. 2, the upstream roller pair 42 (transport roller pair 42) is provided on the second transport path 6 upstream of the apex 6T of the curved path 6A. The downstream roller pair 43 (registration roller pair 43) is provided on the second transport path 6 downstream of the apex 6T. Specifically, the upstream roller pair 42 is provided slightly downstream from the upstream end of the curved path 6A, and the downstream roller pair 43 is provided at the downstream end of the curved path 6A (or a straight portion of the first transport path 5). Note that the apex 6T of the curved path 6A refers to the portion protruding most to the left in FIG. 2, but does not strictly refer to only one point but refers to a portion that includes a certain range.

[0043] <First rib, second rib> The first rib 44 is disposed between the upstream roller pair 42 and the peak 6T, and the second rib 45 is disposed between the peak 6T and the downstream roller pair 43. The first rib 44 is disposed downstream of the upstream roller pair 42 and upstream of the peak 6T so as to be able to appear and disappear into the curved path 6A from the radially outer side of the curved path 6A. The second rib 45 is disposed upstream of the downstream roller pair 43 and downstream of the peak 6T so as to be able to appear and disappear into the curved path 6A from the radially inner side of the curved path 6A. The first rib 44 and the second rib 45 are each formed in a substantially cylindrical shape (substantially disc-shaped) and contact (or are disposed so as to be able to contact) the paper sheet P while protruding into the curved path 6A. As will be described in detail later, the first rib 44 and the second rib 45 are disposed so as to be able to contact the paper sheet P and rotate about their axes. Needless to say, openings are formed in the outer diameter surface 6B and the inner diameter surface 6C of the curved path 6A to allow the first rib 44 and the second rib 45 to appear and disappear.

[0044] <Interlocking part> The interlocking portion 46 is provided at the rear (or front) of the device main body 2 (curved path 6A) so as not to impede the transport of the paper P. The interlocking portion 46 has a function of interlocking the first rib 44 and the second rib 45 to move in and out of the curved path 6A. Specifically, as shown in FIG. 3 , the interlocking portion 46 is a so-called link mechanism, and has a first link portion 51, a second link portion 52, and a biasing member 53.

[0045] (First link) The first link portion 51 is formed, for example, from a metal plate in an L-shape (or a T-shape) and is attached to the first rib 44. The first rib 44 is supported at one end of the first link portion 51 so as to be rotatable about an axis. A first axis 51A is provided at a bent portion of the first link portion 51, and the first link portion 51 is supported by the device main body 2 (or a member constituting the curved path 6A) via the first axis 51A. The first link portion 51 is provided so as to be rotatable about the first axis 51A. A substantially cylindrical interlocking protrusion 51B is protruded from the other end of the first link portion 51.

[0046] (Second link) The second link portion 52 is formed, for example, in an I-shape from a metal plate and is attached to the second rib 45. The second rib 45 is supported at one end of the second link portion 52 so as to be rotatable around the axis. A second axis 52A is provided at one end of the second link portion 52, and the second link portion 52 is supported by the device main body 2 (or a member constituting the curved path 6A) via the second axis 52A. The second link portion 52 is provided so as to be rotatable around the second axis 52A. An interlocking groove portion 52B extending obliquely is formed from the middle of the second link portion 52 to the other end. An interlocking protrusion portion 51B of the first link portion 51 is slidably inserted into the interlocking groove portion 52B. By inserting the interlocking protrusion portion 51B into the interlocking groove portion 52B, the second link portion 52 is rotatably and slidably connected to the first link portion 51.

[0047] (biasing member) The biasing member 53 is a so-called tension coil spring, and is installed between the other end of the second link portion 52 and the device body 2. The biasing member 53 biases (pulls) the other end of the second link portion 52 radially inward. In other words, the biasing member 53 indirectly biases the second rib 45 via the second link portion 52 in a direction that causes the second rib 45 to protrude into the curved path 6A. Note that the biasing member 53 may also be considered to indirectly bias the first rib 44 in a direction that causes the first rib 44 to retract from the curved path 6A via the first link portion 51 engaged with the second link portion 52.

[0048] [Operation of the media guide device] Next, the operation of the medium guide device 35, that is, the movement of the first rib 44 and the second rib 45, will be described with reference to Figures 3 to 5. Figure 4 is a front view showing the medium guide device 35 (second transport state S2 (early stage)). Figure 5 is a front view showing the medium guide device 35 (second transport state S2 (late stage)).

[0049] <First conveying state> First, a first transport state S1 will be described in which the paper sheet P is nipped and transported by the upstream roller pair 42 but not nipped and transported by the downstream roller pair 43. As shown in FIG. 3, in the first transport state S1, the interlocking portion 46 retracts the first rib 44 from the curved path 6A and causes the second rib 45 to protrude into the curved path 6A. Specifically, the biasing force of the biasing member 53 rotates the first link portion 51 and the second link portion 52 so as to retract the first rib 44 from the curved path 6A and cause the second rib 45 to protrude into the curved path 6A. At this time, the interlocking protrusion 51B of the first link portion 51 abuts against the other end (the opposite side to the second rib 45) of the interlocking groove portion 52B of the second link portion 52. Note that the first rib 44 retracting from the curved path 6A does not require the first rib 44 to be completely retracted from the curved path 6A, but rather means that the first rib 44 is allowed to slightly protrude from the outer diameter surface 6B of the curved path 6A. Furthermore, the second rib 45 protruding into the curved path 6A means that the second rib 45 does not obstruct the transport of the paper P, but lightly contacts the paper P, and guides the paper P along the outer diameter surface 6B of the curved path 6A. Furthermore, even when the paper P is not being transported (a state in which the image formation process is not being performed and the paper P is stopped), the first transport state S1 is established.

[0050] Because the first rib 44 is retracted from the curved path 6A, a wide gap is maintained between the inner diameter surface 6C and the outer diameter surface 6B on the upstream side of the curved path 6A. This allows the paper sheet P to smoothly enter the curved path 6A. The paper sheet P that enters the curved path 6A is pressed against the outer diameter surface 6B of the curved path 6A and is conveyed while curving along (in contact with) the outer diameter surface 6B. Because the second rib 45 protrudes into the curved path 6A, it comes into contact with (or is able to come into contact with) the inner surface of the paper sheet P conveyed along the outer diameter surface 6B (it does not have to be in constant contact). This allows the paper sheet P to be guided as it is conveyed along the outer diameter surface 6B of the curved path 6A. When the second rib 45 comes into contact with the paper sheet P, it rotates around its axis to guide the paper sheet P.

[0051] <Second transport state> Next, the second transport state S2 in which the paper sheet P is nipped and transported by the downstream roller pair 43 will be described. As shown in FIG. 4, in the second transport state S2, the interlocking unit 46 causes the first rib 44 to protrude into the curved path 6A and the second rib 45 to retract from the curved path 6A. Specifically, in the early stage of the second transport state S2, when the paper sheet P continues to be nipped and transported by the upstream roller pair 42 and also begins to be nipped and transported by the downstream roller pair 43, the paper sheet P is pulled radially inward from the outer diameter surface 6B of the curved path 6A and begins to be transported along the inner diameter surface 6C. Then, the second rib 45 is pressed by the transported paper sheet P as shown by the hollow arrow in FIG. 4, causing the second link unit 52 to rotate (clockwise in FIG. 4) and retract from the curved path 6A against the biasing force of the biasing member 53. As the second link portion 52 rotates about the second shaft 52A, the first link portion 51 rotates about the first shaft 51A (counterclockwise in FIG. 4 ) while sliding the interlocking protrusion 51B along the interlocking groove 52B of the second link portion 52 toward the second rib 45. In other words, the first link portion 51 rotates in conjunction with the second link portion 52, sliding relatively with respect to the second link portion 52, so as to cause the first rib 44 to protrude into the curved path 6A. At this time, the interlocking protrusion 51B of the first link portion 51 abuts against one end (the side of the second rib 45) of the interlocking groove 52B of the second link portion 52.

[0052] Note that the second rib 45 retracting from the curved path 6A does not require the second rib 45 to be completely retracted from the curved path 6A, but means that the second rib 45 is allowed to slightly protrude from the inner diameter surface 6C of the curved path 6A. Also, the first rib 44 protruding into the curved path 6A means that the first rib 44 does not obstruct the transport of the paper P, but lightly contacts the paper P, and guides the paper P along the inner diameter surface 6C of the curved path 6A.

[0053] In the early stage of the second transport state S2, the second rib 45 is retracted from the curved path 6A, ensuring a wide gap between the inner diameter surface 6C and the outer diameter surface 6B downstream of the curved path 6A. This ensures smooth transport of the paper sheet P along (in contact with) the inner diameter surface 6C of the curved path 6A. Furthermore, the first rib 44 protrudes into the curved path 6A, so it comes into contact with (or is able to come into contact with) the outer surface of the paper sheet P transported along the inner diameter surface 6C (although it does not have to be in constant contact)). This makes it possible to guide the paper sheet P transported along the inner diameter surface 6C of the curved path 6A. When the first rib 44 comes into contact with the paper sheet P, it rotates around its axis to guide the paper sheet P.

[0054] 5, when the rear end of the paper sheet P passes the upstream roller pair 42 and enters the later stage of the second transport state S2, the stiffness (restoring force) of the paper sheet P curved along the inner diameter surface 6C causes the rear end of the paper sheet P to spring up radially outward of the curved path 6A (see the arrow indicated by the dashed line in FIG. 5). However, as described above, because the first rib 44 protrudes into the curved path 6A, the rear side of the paper sheet P comes into contact with the first rib 44 and is prevented from springing up.

[0055] As the transport of the paper sheet P progresses and the pressing of the paper sheet P against the second rib 45 is released, the second link portion 52 is urged by the urging member 53 to rotate (counterclockwise in FIG. 3) so as to cause the second rib 45 to protrude into the curved path 6A. The first link portion 51 rotates (clockwise in FIG. 3) in conjunction with the second link portion 52 to retract the first rib 44 from the curved path 6A.

[0056] In the medium guiding device 35 according to the first embodiment described above, when the medium guiding device 35 is in the first transport state S1, the interlocking unit 46 retracts the first rib 44 from the curved path 6A and protrudes the second rib 45 into the curved path 6A (see FIG. 3). With this configuration, the first rib 44 does not obstruct the paper sheet P (medium) being transported along the outer diameter surface 6B of the curved path 6A. Furthermore, the second rib 45 contacts the paper sheet P from the radially inner side, thereby guiding the paper sheet P being transported along the outer diameter surface 6B of the curved path 6A. Furthermore, when the medium guiding device 35 is in the second transport state S2, the interlocking unit 46 protrudes the first rib 44 into the curved path 6A and retracts the second rib 45 from the curved path 6A (see FIGS. 4 and 5). With this configuration, the first rib 44 contacts the paper sheet P from the radially outer side, thereby preventing the rear side of the paper sheet P from bouncing up after passing through the upstream roller pair 42. Furthermore, the second rib 45 does not obstruct the paper sheet P being transported along the inner diameter surface 6C of the curved path 6A. This ensures smooth transport of the paper sheet P along the curved path 6A while suppressing the generation of collision noise caused by the rear end of the paper sheet P bouncing up.

[0057] Furthermore, in the medium guiding device 35 according to the first embodiment, the interlocking unit 46 includes a link mechanism, and the link mechanism is activated by utilizing the force of the paper P being nipped and transported by the downstream roller pair 43 and pulled from the outer diameter surface 6B to the inner diameter surface 6C of the curved path 6A. This configuration allows the first rib 44 and the second rib 45 to be interlocked and operated to reverse their protruding and retracting states without using a power source such as a motor. Furthermore, there is no need for a sensor to detect the activation timing of the two ribs 44, 45, or a controller to control the power source and sensor. This reduces the manufacturing cost of the medium guiding device 35 and running costs such as power consumption.

[0058] Furthermore, according to the medium guiding device 35 of the first embodiment, the ribs 44, 45 rotate while contacting the paper P, so that the transport of the paper P is not impeded and smooth transport of the paper P can be ensured.

[0059] In the medium guide device 35 according to the first embodiment, the biasing member 53 is a tension coil spring that pulls the second link portion 52, but by changing the arrangement, a compression coil spring that pushes the second link portion 52 can also be used (not shown). Also, the biasing member 53 may be provided so as to pull or push the first link portion 51 instead of the second link portion 52 (not shown). Also, the biasing member 53 is not limited to a coil spring, and may be an elastic body such as a leaf spring or rubber (not shown).

[0060] Furthermore, in the medium guide device 35 according to the first embodiment, the biasing member 53 indirectly biases the second rib 45 via the second link portion 52, but the present invention is not limited to this. For example, if the first rib 44 (or the second rib 45) is provided so as not to rotate, the biasing member 53 may be connected to the first rib 44 (or the second rib 45) and may directly bias the first rib 44 (or the second rib 45) (not shown).

[0061] Furthermore, in the media guide device 35 of the first embodiment, an interlocking protrusion 51B is provided on the first link portion 51 and an interlocking groove portion 52B is provided on the second link portion 52, but this is not limited to this, and an interlocking groove portion 52B may be provided on the first link portion 51 and an interlocking protrusion 51B may be provided on the second link portion 52 (not shown).

[0062] Furthermore, in the media guide device 35 according to the first embodiment, the interlocking unit 46 interlocks the first rib 44 and the second rib 45 to extend and retract without using any other power source. However, the present invention is not limited to this. For example, the biasing member 53 may be omitted, and the interlocking unit 46 may include a driving unit (not shown) such as a solenoid (a modified example of the first embodiment). In this case, for example, the tip of the plunger of the solenoid may be rotatably connected to the first link unit 51 or the second link unit 52, and the solenoid may be driven and controlled by a control device to reciprocate the plunger, thereby swinging the link units 51 and 52 and extending and retracting the ribs 44 and 45 (not shown). Furthermore, the interlocking unit 46 may include a detection unit such as a reflective or transmissive optical sensor, and the detection unit may drive and control the driving unit such as a solenoid when it detects that the paper P has passed through the downstream roller pair 43.

[0063] [Other embodiments] Other embodiments will be described below with reference to Figs. 6 to 9. Fig. 6 is a front view showing a medium guiding device 36 according to a second embodiment (first transport state S1). Fig. 7 is a front view showing a medium guiding device 36 according to the second embodiment (second transport state S2). Fig. 8 is a front view showing a medium guiding device 37 according to a third embodiment (first transport state S1). Fig. 9 is a front view showing a medium guiding device 37 according to the third embodiment (second transport state S2). In the following description (including modified examples), components that are the same as or correspond to those of the medium guiding device 35 according to the first embodiment described above will be given the same reference numerals, and descriptions thereof will be omitted.

[0064] [Second embodiment] As shown in FIG. 6, in a medium guide device 36 according to the second embodiment, an interlocking unit 47 has a drive unit 61, a detection unit 62, and a biasing member 63 instead of a link mechanism.

[0065] (Drive unit) The drive unit 61 is, for example, a servo motor that can control the rotation angle of the drive shaft 61A. The drive unit 61 is electrically connected to and controlled by the control device of the multifunction device 1. An arm 61B is attached to the drive shaft 61A of the drive unit 61, and the first rib 44 is rotatably supported at the tip of the arm 61B. The drive unit 61 swings the arm 61B (drive shaft 61A) to cause the first rib 44 to appear and disappear from the curved path 6A.

[0066] (Detection unit) The detection unit 62 is, for example, a transmissive optical sensor in which a light-emitting unit and a light-receiving unit are arranged opposite each other, and is provided near the second rib 45. The detection unit 62 is electrically connected to the control device of the multifunction device 1 and transmits a detection signal to the control device. The second rib 45 is rotatably supported by a support portion 64, which is slidably supported by the device body 2 so that the second rib 45 can appear and disappear from the curved path 6A. When the second rib 45 retracts from the curved path 6A, a light-blocking piece 64A formed on the support portion 64 enters between the light-emitting unit and the light-receiving unit, blocking the light emitted from the light-emitting unit (see FIG. 7). This allows the detection unit 62 to detect the second rib 45 that has retracted from the curved path 6A.

[0067] (biasing member) The urging member 63 is, for example, a compression coil spring, and is provided so as to be wound around the support portion 64. One end of the urging member 63 abuts against the flange portion 64B of the support portion 64, and the other end of the urging member 63 abuts against the device main body 2. The urging member 63 urges the second rib 45 via the support portion 64 so as to protrude into the curved path 6A.

[0068] The control device is a component of the multifunction device 1, but may also be considered to be a component of the media guide device 36 or the drive unit 61. Alternatively, a dedicated control device for the media guide device 36 (drive unit 61) may be provided separately from the control device of the multifunction device 1, and the drive unit 61 and the detection unit 62 may be controlled by the dedicated control device (not shown).

[0069] [Operation of the media guide device] Next, the operation of the medium guide device 36 (interlocking unit 47) will be briefly described.

[0070] 6, in the first transport state S1, the drive unit 61 retracts the first rib 44 from the curved path 6A, and the second rib 45 is biased by the biasing member 63 to protrude into the curved path 6A. Specifically, the detection unit 62 transmits a detection signal indicating that it has not detected the second rib 45 (light-shielding piece 64A) that has retracted from the curved path 6A to the control device, and the control device receives the detection signal (detection result) from the detection unit 62 and controls the rotation of the drive unit 61 to retract the first rib 44 from the curved path 6A (or maintains the retracted state).

[0071] 7, in the second transport state S2, the second rib 45 is pressed by the paper P being transported and retreats from the curved path 6A against the biasing force of the biasing member 63, and the drive unit 61 causes the first rib 44 to protrude into the curved path 6A based on the detection unit 62 detecting the retreated second rib 45 (light-shielding piece 64A). Specifically, the detection unit 62 transmits a detection signal indicating that the second rib 45 retreated from the curved path 6A to the control device, and the control device receives the detection signal (detection result) from the detection unit 62 and controls the rotation of the drive unit 61 to cause the first rib 44 to protrude into the curved path 6A (or maintain the protruding state).

[0072] As the transport of the paper P progresses and the pressing of the paper P against the second rib 45 is released, the second rib 45 is urged by the urging member 63 and protrudes into the curved path 6A (see FIG. 6). The detection unit 62 no longer detects the second rib 45, so the control device controls the rotation of the drive unit 61 to move the first rib 44 away from the curved path 6A (see FIG. 6).

[0073] In the medium guiding device 36 according to the second embodiment described above, in the first transport state S1, the drive unit 61 retracts the first rib 44, and the second rib 45 is biased by the biasing member 63 to protrude, and in the second transport state S2, the drive unit 61 protrudes the first rib 44, and the second rib 45 is pushed by the paper P to retract. This configuration can achieve the same effects as the medium guiding device 35 according to the first embodiment, such as suppressing the generation of collision noise caused by the rear end of the paper P bouncing up while ensuring smooth transport of the paper P along the curved path 6A. Furthermore, according to the medium guiding device 36 according to the second embodiment, the first rib 44 protrudes and retracts in response to the driving force of the drive unit 61, separately from the protruding and retracting operation of the second rib 45. Therefore, for example, it is possible to advance (or delay) the timing at which the first rib 44 protrudes, or to adjust the protruding amount of the first rib 44 (including not protruding) depending on the thickness (stiffness) or type of the paper P.

[0074] In the medium guide device 36 (interlocking unit 47) according to the second embodiment, the drive unit 61 is a servo motor, but this is not limited thereto and may be, for example, a solenoid that can reciprocate a plunger (not shown). In addition, the detection unit 62 is not limited to a transmission-type optical sensor and may be, for example, a reflective optical sensor that detects light reflected by the light-shielding piece 64A, or may be a microswitch or the like that is pressed by the support unit 64 (not shown). In addition, the biasing member 63 is not limited to a coil spring and may be, for example, an elastic body such as a leaf spring or rubber (not shown).

[0075] [Third embodiment] As shown in FIG. 8, in a medium guide device 37 according to the third embodiment, an interlocking unit 48 has a first driving unit 71, a second driving unit 72, and a detecting unit 73.

[0076] (First drive unit, second drive unit) The first drive unit 71 (first drive shaft 71A, first arm portion 71B) and the second drive unit 72 (second drive shaft 72A, second arm portion 72B) each have a structure similar to that of the drive unit 61 (drive shaft 61A, arm portion 61B) of the media guide device 36 of the second embodiment. The first drive unit 71 moves the first rib 44 in and out of the curved path 6A, and the second drive unit 72 moves the second rib 45 in and out of the curved path 6A.

[0077] (Detection unit) The detection unit 73 is, for example, a reflective optical sensor in which a light-emitting unit and a light-receiving unit are arranged side by side, and is provided near the downstream side of the downstream roller pair 43. The detection unit 73 is electrically connected to the control device of the multifunction device 1 and transmits a detection signal to the control device. When the leading edge of the paper P passes the downstream roller pair 43, light emitted from the light-emitting unit is reflected by the paper P and enters the light-receiving unit. This allows the detection unit 73 to detect that the downstream roller pair 43 is transporting the paper P.

[0078] [Operation of the media guide device] Next, the operation of the medium guide device 37 (interlocking unit 48) will be briefly described.

[0079] 8, in the first transport state S1, the first drive unit 71 retracts the first rib 44 from the curved path 6A, and the second drive unit 72 protrudes the second rib 45 into the curved path 6A. Specifically, the detection unit 73 transmits a detection signal indicating that the paper P is not detected to the control device, and the control device receives the detection signal (detection result) from the detection unit 73, controls the rotation of the first drive unit 71 to retract the first rib 44 from the curved path 6A, and controls the rotation of the second drive unit 72 to protrude the second rib 45 into the curved path 6A (or maintains the retracted / protruded state).

[0080] 9, in the second transport state S2, when the detection unit 73 detects that the downstream roller pair 43 is transporting the paper P, the first drive unit 71 causes the first rib 44 to protrude into the curved path 6A, and the second drive unit 72 causes the second rib 45 to retract from the curved path 6A. Specifically, the detection unit 73 sends a detection signal indicating that the paper P has been detected to the control device, and the control device receives the detection signal (detection result) from the detection unit 73, controls the rotation of the first drive unit 71 to protrude the first rib 44 into the curved path 6A, and controls the rotation of the second drive unit 72 to retract the second rib 45 from the curved path 6A (or maintains the retracted / protruded state).

[0081] As the transport of the paper P progresses and the detection unit 73 no longer detects the paper P, the control device controls the rotation of the first drive unit 71 to move the first rib 44 away from the curved path 6A, and controls the rotation of the second drive unit 72 to move the second rib 45 protrude into the curved path 6A (see Figure 8).

[0082] The media guide device 37 of the third embodiment described above can achieve the same effects as the media guide devices 35-36 of the first and second embodiments, such as being able to suppress the generation of collision noise caused by the rear end of the paper P bouncing up while ensuring smooth transport of the paper P along the curved path 6A.

[0083] In the medium guiding device 37 (interlocking unit 48) according to the third embodiment, the first driving unit 71 and the second driving unit 72 are servo motors, but are not limited to this and may be, for example, a solenoid that can reciprocate a plunger (not shown). The detection unit 73 is also not limited to a reflective optical sensor and may be, for example, a transmissive optical sensor, a capacitance sensor that detects a change in capacitance when the downstream roller pair 43 pinches the paper P, or a camera that photographs the paper P (not shown). The detection unit 73 of the medium guiding device 37 according to the third embodiment may be employed as the detection unit 62 of the medium guiding device 36 according to the second embodiment (not shown).

[0084] Although the medium guiding devices 35-37 according to the first to third embodiments are provided on the curved path 6A downstream of the second transport path 6, the present invention is not limited to this. For example, the medium guiding devices 35-37 may be provided on a substantially U-shaped curved portion (see FIG. 1) on the upstream side of the first transport path 5 (near the paper feed cassette 3). In this case, the paper feed roller pair 40 is the upstream roller pair, and the transport roller pair 41 is the downstream roller pair. In this way, the medium guiding devices 35-37 can be applied to any path that transports a medium such as paper P while curving it.

[0085] [First Modification] Although the medium guiding devices 35-37 according to the first to third embodiments are provided in the image forming apparatus 1A, the present invention is not limited to this. For example, as shown in Fig. 10, the medium guiding devices 35-37 may be provided in the document transport path 30 of the image reading device 1B, which is curved in a substantially U-shape (first modified example). In this case, the document transport roller pair 32 arranged on the upstream side of the curved portion is the upstream roller pair, and the document transport roller pair 32 arranged on the downstream side of the curved portion is the downstream roller pair.

[0086] [Second Modification] As shown in FIG. 11, the multifunction device 1 may be equipped with a post-processing device 7 that aligns a plurality of sheets P and staples and bundles the aligned sheets P. Inside the post-processing device 7, a post-processing transport path 8 that continues from the first transport path 5 of the image forming apparatus 1A is provided. The media guiding devices 35-37 according to the first to third embodiments may be provided in the post-processing transport path 8 of the post-processing device 7 that is curved in a substantially U-shape (second modified example). In this case, the post-processing roller pair 74 arranged upstream of the curved portion is the upstream roller pair, and the post-processing roller pair 74 arranged downstream of the curved portion is the downstream roller pair.

[0087] In the media guide devices 35 to 37 according to the first to third embodiments (including their respective modified examples; the same applies below), the first rib 44 and the second rib 45 are formed in a substantially cylindrical shape and are rotatable about their respective axes, but the present invention is not limited to this. For example, at least one of the first rib 44 and the second rib 45 may be formed in a semicircular or trapezoidal shape, or may be provided so as to be non-rotatable (not shown). Also, while one first rib 44 and one second rib 45 are provided, the present invention is not limited to this. For example, multiple first ribs 44 (multiple second ribs 45) may be attached at intervals to a shaft extending in the front-rear direction (not shown).

[0088] Furthermore, the image forming apparatus 1A described above is a monochrome printer, but is not limited to this and may be a color printer, a copier, a facsimile, etc. Furthermore, the image forming method of the image forming apparatus 1A is an electrophotographic type, but is not limited to this and may be an inkjet type.

[0089] The above-described embodiment shows one aspect of the media guide device, image forming device, image reading device, and post-processing device according to the present invention, and the technical scope of the present invention is not limited to the above-described embodiment. The present invention may be variously changed, substituted, or modified within the scope of the technical concept, and the claims include all embodiments that may fall within the scope of the technical concept. [Explanation of symbols]

[0090] 1 Multifunction device 1A Image forming device 1B Image reader 5 First transport path (transport path) 6 Second transport path (transport path) 6A Curved Path 6T apex 7 Aftertreatment device 8 Post-processing transport path (transport path) 30 Document transport path (transport path) 32 Document transport roller pair 35, 36, 37 Media guide device 42 Upstream roller pair 43 Downstream Roller Pair 44 First Rib 45 Second Rib 46, 47, 48 Interlocking parts 51 First link 51A 1st axis 52 Second link 52A 2nd axis 53,63 biasing member 61 Drive unit 62,73 Detection unit 71 First drive unit 72 Second drive unit 74 Post-processing roller pair S1 First transfer state S2 Second transport state

Claims

1. a pair of upstream rollers that are provided upstream of an apex of a curved path in a conveying direction of the medium, the upstream rollers rotating while sandwiching the medium to convey the medium; and a downstream roller pair that is provided downstream of the apex portion in the conveying direction in the conveying path and that conveys the medium by rotating while sandwiching the medium; a first rib that is provided downstream of the upstream roller pair in the transport direction and upstream of the apex portion in the transport direction so as to be able to appear and disappear from the curved path from the radially outer side of the curved path, and that contacts the medium while protruding into the curved path; a second rib that is provided upstream of the downstream roller pair in the transport direction and downstream of the apex portion in the transport direction so as to be able to appear and disappear from the curved path from the radially inner side of the curved path, and that contacts the medium while protruding into the curved path; an interlocking portion that interlocks the first rib and the second rib to appear and disappear on the curved path, When the medium being conveyed while being sandwiched between the upstream roller pair is in a first conveying state in which the medium is separated from the downstream roller pair, the interlocking portion retracts the first rib from the curved path and protrudes the second rib into the curved path, A media guide device characterized in that when the medium is in a second transport state in which it is transported while being sandwiched between the downstream roller pair, the interlocking portion causes the first rib to protrude into the curved path and the second rib to retract from the curved path.

2. The interlocking portion is a first link portion attached to the first rib and rotatable about a first axis; a second link portion attached to the second rib, rotatable about a second axis, and rotatably and slidably connected to the first link portion; a biasing member that directly or indirectly biases the first rib or the second rib, In the first transport state, the biasing force of the biasing member rotates the first link portion and the second link portion so as to retract the first rib from the curved path and protrude the second rib into the curved path, The media guide device described in claim 1, characterized in that when in the second transport state, the second rib is pressed by the transported medium, causing the second link portion to rotate and retreat from the curved path against the biasing force of the biasing member, and the first link portion rotates so as to slide relative to the second link portion and cause the first rib to protrude into the curved path.

3. The interlocking portion is a drive unit that causes the first rib to appear and disappear from the curved path; a detection unit that detects the second rib that has retreated from the curved path; a biasing member that biases the second rib so as to protrude into the curved path, In the first transport state, the driving unit retracts the first rib from the curved path, and the second rib is biased by the biasing member to protrude into the curved path, The media guide device of claim 1, characterized in that when in the second transport state, the second rib is pressed by the medium being transported and retreats from the curved path against the biasing force of the biasing member, and based on the detection unit detecting the retreated second rib, the drive unit protrudes the first rib into the curved path.

4. The interlocking portion is a first driving unit that causes the first rib to appear and disappear along the curved path; a second drive unit that causes the second rib to appear and disappear from the curved path; a detection unit that detects that the downstream roller pair is transporting the medium, In the first transport state, the first driving unit retracts the first rib from the curved path, and the second driving unit protrudes the second rib into the curved path. The media guide device described in claim 1, characterized in that when in the second transport state, based on the detection unit detecting the transport of the medium by the downstream roller pair, the first drive unit protrudes the first rib into the curved path and the second drive unit retracts the second rib from the curved path.

5. 5. The medium guide device according to claim 1, wherein the first rib and the second rib are provided so as to be rotatable about an axis while in contact with the medium.

6. An image forming apparatus comprising the medium guide device according to any one of claims 1 to 4.

7. An image reading device comprising the medium guide device according to any one of claims 1 to 4.

8. A post-processing device comprising the media guide device according to any one of claims 1 to 4.

Images