Image forming apparatus

Abstract

To prevent recording media from clogging.SOLUTION: An image forming apparatus includes a downstream guide 60 that forms a part of a transport path for a recording medium and extends in a first direction intersecting a transport direction. The downstream guide 60 has a first base portion 67 and a first protrusion 61 that protrudes upstream in the transport direction from the first base portion 67. The first protrusion 61 has a first inclined portion 63 having a protrusion upstream end 62 on the most upstream side in the transport direction and a second inclined portion 65 arranged between the first inclined portion 63 and a first base portion 67. An upstream end of the second inclined portion 65 intersects with the first direction when viewed from a direction perpendicular to both the transport direction and the first direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image on a conveyed recording medium. [Background technology]

[0002] Image forming devices, such as MFPs, generally transport recording media and form images on the recording media as they are being transported. These image forming devices have a configuration that can open at least a portion of the transport path in case a paper jam occurs in the paper transport path. For example, the device is configured with multiple components that divide the transport path in the direction in which the recording media is transported. When one component moves relative to the other components, a portion of the transport path is opened.

[0003] For example, Japanese Patent Application Laid-Open No. 2011-32040 describes an image forming apparatus in which a second guide section that constitutes a sheet transport path rotates around one end in the sheet transport direction as a rotation center to open and close the sheet transport path, and is configured by a movable transport guide having a comb-tooth-shaped comb-teeth portion formed at the other end, and a fixed transport guide that is provided at the other end of the movable transport guide so that the distance from the first guide section to the movable transport guide is wider than that of the movable transport guide, forming a step between the movable transport guide and the second guide section, and that has a comb-tooth-shaped comb-teeth portion formed at the end of the movable transport guide that fits into the comb-teeth portion at the opening and closing end of the movable transport guide, and in which the distances from the rotation axis that is the rotation center of the movable transport guide to the opposing comb-teeth-shaped tips of the fixed transport guide and the movable transport guide are different in the width direction.

[0004] However, in the image forming apparatus described in JP 2011-32040 A, there is a risk that the recording medium may get caught in the gap between the fixed conveyance guide and the movable conveyance guide. In particular, because the gap between the fixed conveyance guide and the movable conveyance guide has a portion parallel to the conveyance direction, when both ends of the recording medium pass through the gap parallel to the conveyance direction, there is a high possibility that the leading edge of the recording medium may get caught in the gap. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-32040 A Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that prevents recording media from clogging. [Means for solving the problem]

[0007] According to one aspect of the present invention, an image forming apparatus includes a first guide portion that forms part of a transport path for a recording medium and extends in a first direction that intersects with the transport direction, the first guide portion having a first base portion and a first convex portion that protrudes upstream of the first base portion in the transport direction, the first convex portion having a first inclined portion having an upstream end of the convex portion that is most upstream in the transport direction of the first convex portion, and a second inclined portion arranged between the first inclined portion and the first base portion, and the upstream end of the second inclined portion intersects with the first direction when viewed from a direction perpendicular to both the transport direction and the first direction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing the appearance of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of an internal configuration of an image forming apparatus. [Figure 3] FIG. 2 is a cross-sectional view of a timing roller and its surroundings. [Figure 4] FIG. 2 is a perspective view of the image forming apparatus with the side door open. [Figure 5] 10A and 10B are diagrams illustrating an example of a downstream guide and an upstream guide. [Figure 6] FIG. 2 is an enlarged view showing an end passing region R1. [Figure 7] FIG. 7 is a cross-sectional view taken along line AA in FIG. 6. [Figure 8]FIG. 7 is a cross-sectional view taken along line BB in FIG. 6. [Figure 9] FIG. 7 is a cross-sectional view taken along line CC in FIG. 6. [Figure 10] FIG. 7 is a cross-sectional view taken along the line DD in FIG. 6. [Figure 11] FIG. 7 is a cross-sectional view taken along the line EE in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. The names and functions of these components are also the same. Therefore, detailed description thereof will not be repeated.

[0010] FIG. 1 is a perspective view showing the appearance of an image forming apparatus according to one embodiment of the present invention. In FIG. 1, mutually orthogonal X, Y, and Z directions are defined. The X and Y directions are parallel to a horizontal plane. In the following description, the X direction is parallel to the left and right of the image forming apparatus 1 and is also referred to as the left-right direction. The positive side of the X direction is the right side, and the negative side of the X direction is the left side. The Y direction is parallel to the depth direction of the image forming apparatus 1 and is also referred to as the front-to-back direction. The negative side of the Y direction is the front direction, and the positive side of the Y direction is the rear direction. The Z direction is parallel to the up-down direction of the image forming apparatus 1 and is also referred to as the up-down direction. The positive side of the Z direction is the up direction, and the negative side of the Z direction is the down direction.

[0011] Referring to FIG. 1, the image forming apparatus 1 has a housing 10 that covers the entire image forming apparatus 1. An operation panel 7 serving as a user interface is disposed on the top surface of the housing 10. The housing 10 has an internal space, in which an image forming unit 3 that forms an image on paper or the like based on image data and a paper feed unit 4 that supplies paper to the image forming unit 3 are disposed. The image forming apparatus 1 also has a side door 11 disposed on the left side surface of the housing 10. The side door 11 can be opened and closed. When the side door 11 is in an open state, the left side of the internal space of the housing 10 is open to the outside. When the side door 11 is in a closed state, the internal space of the housing 10 is not open to the outside.

[0012] FIG. 2 is a cross-sectional view schematically illustrating an example of the internal configuration of an image forming apparatus. Referring to FIG. 2, image forming apparatus 1 includes image forming units 20Y, 20M, 20C, and 20K for yellow, magenta, cyan, and black, respectively. Here, "Y," "M," "C," and "K" represent yellow, magenta, cyan, and black, respectively. Printing data for yellow, magenta, cyan, and black are input to image forming units 20Y, 20M, 20C, and 20K, respectively. Image forming units 20Y, 20M, 20C, and 20K differ only in the color of the toner they handle, so here, image forming unit 20Y for forming yellow images will be described.

[0013] The image forming unit 20Y includes an exposure device 21Y, a photosensitive drum 23Y, a charging roller 22Y, a developing device 24Y, a primary transfer roller 25Y, a drum cleaning blade 27Y, and a toner cartridge 50Y. Yellow printing data is input to the exposure device 21Y. The charging roller 22Y uniformly charges the surface of the photosensitive drum 23Y. The primary transfer roller 25Y transfers the toner image formed on the photosensitive drum 23Y onto the intermediate transfer belt 30, which is an image carrier, by the action of an electric field. The drum cleaning blade 27Y removes any residual toner remaining on the photosensitive drum 23Y.

[0014] The toner cartridge 50Y contains yellow toner. The toner cartridge 50Y rotates using a cartridge motor as a drive source and discharges toner to the outside. The toner discharged from the toner cartridge 50Y is supplied to the developing device 24Y. The toner cartridge 50Y supplies toner to the developing device 24Y when the remaining amount of toner contained in the developing device 24Y falls below a predetermined lower limit.

[0015] Around the photosensitive drum 23Y, a charging roller 22Y, an exposure device 21Y, a developing device 24Y, a primary transfer roller 25Y, and a drum cleaning blade 27Y are arranged in this order along the rotation direction of the photosensitive drum 23Y.

[0016] The photoreceptor drum 23Y is charged by the charging roller 22Y and then irradiated with laser light emitted by the exposure device 21Y. The exposure device 21Y exposes an image-corresponding portion of the surface of the photoreceptor drum 23Y to light to form an electrostatic latent image. This forms an electrostatic latent image on the photoreceptor drum 23Y. Next, the developing device 24Y develops the electrostatic latent image formed on the photoreceptor drum 23Y with charged toner. Specifically, toner is placed on the electrostatic latent image formed on the photoreceptor drum 23Y by the action of an electric field, thereby forming a toner image on the photoreceptor drum 23Y. The toner image formed on the photoreceptor drum 23Y is transferred onto the intermediate transfer belt 30, which serves as an image carrier, by the action of an electric field using the primary transfer roller 25Y. Any toner remaining on the photoreceptor drum 23Y that has not been transferred is removed from the photoreceptor drum 23Y by the drum cleaning blade 27Y.

[0017] Meanwhile, the intermediate transfer belt 30 is suspended tightly by a drive roller 33 and a driven roller 34. When the drive roller 33 rotates counterclockwise in FIG. 2, the intermediate transfer belt 30 rotates counterclockwise in the drawing at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

[0018] As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer toner images onto the intermediate transfer belt 30. The timing at which each of the image forming units 20Y, 20M, 20C, and 20K transfers a toner image onto the intermediate transfer belt 30 is adjusted by detecting the reference marks on the intermediate transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

[0019] The toner image formed on intermediate transfer belt 30 is transferred to paper by the action of electric field force by secondary transfer roller 26, which is a transfer member. The paper is transported by timing roller 31 to a nip portion where intermediate transfer belt 30 and secondary transfer roller 26 come into contact. The paper with the toner image transferred thereto is transported to fixing device 51.

[0020] The fixing device 51 includes a heating unit and a pressure roller. The heating unit is disposed opposite the pressure roller and forms a nip between the heating unit and the pressure roller. The nip is the area where the pressure roller and the heating unit come into contact with each other. The pressure roller is pressed against the heating unit with a predetermined pressure.

[0021] A sheet of paper carrying a toner image on its surface is transported from below to above fixing device 51, and the paper passes through the nip. While the paper passes through the nip, fixing device 51 applies heat and pressure to the paper, fixing the toner to the paper. The paper is then ejected onto paper ejection tray 39.

[0022] A belt cleaning blade 28 is provided upstream of the image forming unit 20Y on the intermediate transfer belt 30. The belt cleaning blade 28 removes toner remaining on the intermediate transfer belt 30 that has not been transferred to paper.

[0023] When forming a full-color image, the image forming apparatus 1 drives all of the image forming units 20Y, 20M, 20C, and 20K. When forming a monochrome image, the image forming apparatus 1 drives only one of the image forming units 20Y, 20M, 20C, and 20K. It is also possible to form an image by combining two or more of the image forming units 20Y, 20M, 20C, and 20K. Here, the image forming apparatus 1 employs a tandem system equipped with image forming units 20Y, 20M, 20C, and 20K that form four different color toners on paper. However, the image forming apparatus 1 may employ a four-cycle system in which the four color toners are transferred sequentially onto paper using a single photosensitive drum.

[0024] A plurality of sheets of paper are set in paper feed cassette 35. The sheets contained in paper feed cassette 35 are supplied one by one to paper feed roller 37A by take-out roller 36 attached to paper feed cassette 35. A plurality of sheets of paper are set in paper feed cassette 35A. The sheets contained in paper feed cassette 35A are supplied one by one to paper feed roller 37 by take-out roller 36A attached to paper feed cassette 35A. Paper feed roller 37 transports the paper to paper feed roller 37A. One or more sheets of paper may also be set in manual feed cassette 35C. The one or more sheets of paper set in manual feed cassette 35C are supplied one by one to paper feed roller 37A by take-out roller 36C attached to manual feed cassette 35C. Paper feed roller 37A transports the paper to timing roller 31. The paper is transported along main transport path 41 toward timing roller 31 .

[0025] Timing roller 31 transports the paper toward the nip formed between secondary transfer roller 26 and drive roller 33. The paper, onto which the toner image formed on intermediate transfer belt 30 has been transferred by secondary transfer roller 26, is transported to fixing device 51. The paper, onto which the toner image has been fixed by fixing device 51, is transported to paper discharge rollers 38.

[0026] The paper discharge rollers 38 are rotated by a torque transmitted from a motor. The paper discharge rollers 38 rotate either forward or reverse. In an operation mode in which an image is formed on one side of the paper, the paper discharge rollers 38 rotate forward to discharge the paper to a paper discharge tray 39. In an operation mode in which an image is formed on both sides of the paper, the paper discharge rollers 38 rotate forward until the paper is transported partway and then rotate reversely. A branch point P2 is provided between the fixing device 51 and the paper discharge rollers 38, to which one end of a reversing path 43 is connected. The reversing path 43 is part of the transport path that transports the paper. The other end of the reversing path 43 is connected to a branch point P1 between the timing roller 31 and the upstream paper feed roller 37. While the paper discharge rollers 38 are rotating in the reverse direction, the paper is guided from the branch point P2 to the reversing path 43 and then from the branch point P1 between the timing roller 31 and the paper feed roller 37 to the main transport path 41. The paper conveyed by paper feed roller 37B provided on reversing path 43 enters main conveying path 41 from branch point P1. The paper advances along main conveying path 41, and its leading edge comes into contact with timing roller 31. After that, the paper is aligned with the conveying direction and then conveyed by timing roller 31 toward the nip formed by secondary transfer roller 26 and drive roller 33.

[0027] 3 is a cross-sectional view of the timing roller and its surroundings. Referring to FIG. 3, a portion of main transport path 41 and a portion of reversing path 43 are formed by inner guide 80, outer guide 81, downstream guide 60, and upstream guide 70. The portion of main transport path 41 and reversing path 43 are spaces sandwiched between two surfaces. Here, the two surfaces forming main transport path 41 are referred to as the first surface and the second surface. Furthermore, the two surfaces forming reversing path 43 are referred to as the third surface and the fourth surface.

[0028] The inner guide 80 is fixed to the left end of the housing 10. The inner guide 80 has an inner surface M2 that forms part of the first surface of the main transport path 41. The outer guide 81 is fixed to the inner wall of the side door 11. The outer guide 81 has an outer surface M1 that forms part of the second surface of the main transport path 41 and a lower surface M7 that forms part of the third surface of the reversing path 43. The outer surface M1 of the outer guide 81 faces part of the inner surface M2 of the inner guide 80. A part of the main transport path 41 is formed between the inner surface M2 of the inner guide 80 and the outer surface M1 of the outer guide 81.

[0029] The upstream guide 70 is fixed to the inner wall of the side door 11 at a position above the outer guide 81. The upstream guide 70 has an upper surface M8 that forms part of the fourth surface of the reversing path 43. A part of the reversing path 43 is formed between the lower surface M7 of the outer guide 81 and the upper surface M8 of the upstream guide 70. The upstream guide 70 has an upstream inclined surface M3 that connects the upper surface M8 in the downstream direction of the reversing path 43. A part of the main conveying path 41 is formed by the upstream inclined surface M3 and the inner surface M2 of the inner guide 80.

[0030] The downstream guide 60 is fixed to the housing 10 at a position spaced a predetermined distance from the inner guide 80. The downstream guide 60 is positioned above the upstream guide 70 at a predetermined distance. The downstream guide 60 is located downstream of the upstream guide 70 in the conveying direction. The downstream guide 60 has a base surface M4 that defines a portion of the second surface of the main conveying path 41. A portion of the main conveying path 41 is formed by the upstream-side inclined surface M3 of the downstream guide 60 and the inner surface M2 of the inner guide 80.

[0031] The timing roller 31 includes a main roller 31A and a sub-roller 31B. The main roller 31A is arranged side by side above the downstream guide 60 in the direction of the conveying path. The main roller 31A has a rotation shaft that is fixed to the housing 10. The main roller 31A rotates by receiving rotational force from a motor. The sub-roller 31B has a rotation shaft that is parallel to the rotation shaft of the main roller 31A and is rotatably fixed to the housing 10. The sub-roller 31B faces the main roller 31A and is positioned in contact with the main roller 31A. The main roller 31A is elastic. The sub-roller 31B is made of metal. A nip is formed where the main roller 31A and the sub-roller 31B contact each other. The rotation shaft of the sub-roller 31B is connected to the rotation shaft of the main roller 31A via a drive gear. The sub-roller 31B rotates in conjunction with the rotation of the main roller 31A.

[0032] 2, the paper conveyed by paper feed roller 37A passes through main transport path 41, and its leading edge abuts against timing roller 31. The paper conveyed by paper feed roller 37B passes through reversal path 43, and its leading edge abuts against timing roller 31. The operation of timing roller 31 is the same when the paper passes through main transport path 41 and when the paper passes through reversal path 43. Here, an example will be described in which the paper is conveyed by paper feed roller 37A.

[0033] With main roller 31A stopped, paper conveyed by paper feed roller 37A comes into contact with the nip formed by main roller 31A and sub-roller 31B. At this time, the leading edge of the paper in the conveyance direction comes into contact with the nip where main roller 31A and sub-roller 31B come into contact, and the portion between timing roller 31 and paper feed roller 37A is curved. This corrects the orientation of the paper so that the leading edge of the paper is parallel to the rotation axis of main roller 31A. For example, if the paper is rectangular with a longitudinal side and a lateral side, the orientation of the paper is corrected so that the longitudinal direction or the lateral direction is parallel to the conveyance direction.

[0034] Thereafter, when the main roller 31A receives a rotational force from the motor and rotates, the paper is transported toward the nip formed between the secondary transfer roller 26 and the drive roller 33. The paper onto which the toner image formed on the intermediate transfer belt 30 has been transferred by the secondary transfer roller 26 is transported to the fixing device 51. The paper onto which the toner image has been fixed by the fixing device 51 is transported to the paper discharge rollers 38.

[0035] FIG. 4 is a perspective view of the image forming apparatus with the side door open. Referring to FIG. 4, when the side door 11 of the housing 10 is open, the left end of the image forming unit 3 is exposed. FIG. 4 also illustrates the fixing device 51, the intermediate transfer belt 30, the timing roller 31, and the downstream guide 60. A first surface, which forms one side of the main transport path 41, is located below the downstream guide 60 of the housing 10. An upstream guide 70 is located inside the side door 11. A second surface, which forms the other side of the main transport path 41, is located below the upstream guide 70 of the side door 11. When the side door 11 is closed, the main transport path 41 is a space sandwiched between the first and second surfaces. When the housing 10 is open, portions of both the first and second surfaces of the main transport path 41 are exposed. This allows the user to easily remove paper jammed in the main transport path 41.

[0036] Fig. 5 is a diagram showing an example of the downstream guide and the upstream guide. Fig. 5 is a diagram showing the downstream guide 60 and the upstream guide 70 when the side door 11 is closed, as viewed from the main transport path 41 side (the negative side in the X direction). Referring to Fig. 5, the downstream guide 60 and the upstream guide 70 are arranged with a predetermined gap between them in the vertical direction. A gap 90 is formed between the downstream guide 60 and the upstream guide 70. Therefore, when the side door 11 is opened or closed, the downstream guide 60 and the upstream guide 70 do not interfere with each other.

[0037] In FIG. 5, the positive side of the Z direction is the paper transport direction. The Y direction, which intersects with the transport direction, is the first direction. The downstream guide 60 and the upstream guide 70 are shaped to extend in the Y direction. A downstream end, which is the end on the downstream side of the upstream guide 70, and an upstream end, which is the end on the upstream side of the downstream guide 60, form multiple end passing regions R1-R4, L1-L4. The end passing regions R1-R4, L1-L4 are regions that are located at different positions in the Y direction. The downstream guide 60 and the upstream guide 70 each have a convex portion and a concave portion, and the end passing regions R1-R4, L1-L4 are regions where one convex portion corresponds to the concave portion of the other.

[0038] Specifically, end pass regions R1-R4 and end pass regions L1-L4 are arranged on either side of the Y-direction center of the downstream guide 60 and the upstream guide 70. The end pass regions R1-R4 are arranged in a row from the center toward the negative side of the Y-direction. The end pass regions L1-L4 are arranged in a row from the center toward the positive side of the Y-direction. End pass regions that are the same distance from the Y-direction center form a pair. The end pass region R1 and the end pass region L1 form a pair, and this pair corresponds to paper whose length in the Y-direction is smaller than W1. The end pass region R2 and the end pass region L2 form a pair, and this pair corresponds to paper whose length in the Y-direction is smaller than W2 but larger than W1. The end pass region R3 and the end pass region L3 form a pair, and this pair corresponds to paper whose length in the Y-direction is smaller than W3 but larger than W2. The end pass region R4 and the end pass region L4 form a pair, and this pair corresponds to paper whose length in the Y-direction is smaller than W4 but larger than W3.

[0039] The paper is transported so that its center in the Y direction passes through the Y-direction centers of the downstream guide 60 and the upstream guide 70. Therefore, when a paper sheet whose length in the Y direction is smaller than W1 is transported, both ends of the paper sheet in the Y direction pass through end pass regions R1 and L1, respectively. When a paper sheet whose length in the Y direction is smaller than W2 but larger than W1 is transported, both ends of the paper sheet in the Y direction pass through end pass regions R2 and L2, respectively. When a paper sheet whose length in the Y direction is smaller than W3 but larger than W2 is transported, both ends of the paper sheet in the Y direction pass through end pass regions R3 and L3, respectively. When a paper sheet whose length in the Y direction is smaller than W4 but larger than W3 is transported, both ends of the paper sheet in the Y direction pass through end pass regions R4 and L4, respectively.

[0040] Fig. 6 is an enlarged view showing the end passing region R1. Referring to Fig. 6, the downstream guide 60 has a first convex portion 61 having a convex portion upstream end 62 on the most upstream side in the conveying direction, and a first base portion 67 located downstream of the convex portion upstream end 62. A base portion upstream end 68 on the most upstream side in the conveying direction of the first base portion 67 is located downstream of the convex portion upstream end 62. The base portion upstream end 68 and the convex portion upstream end 62 are parallel to the Y direction.

[0041] The first protrusion 61 has a first inclined portion 63 having a protrusion upstream end 62 and a second inclined portion 65 disposed between the first inclined portion 63 and a first base portion 67. The inclined upstream end 66, which is the upstream end of the second inclined portion 65 in the conveying direction, intersects with the Y direction when viewed from a direction perpendicular to both the conveying direction and the Y direction. The inclined upstream end 66 of the second inclined portion 65 inclines from the center to the end in the Y direction from the downstream side to the upstream side in the conveying direction. In the end passing region R1, the inclined upstream end 66 of the second inclined portion 65 is located more upstream in the conveying direction as the distance from the center to the negative Y direction increases among multiple different positions in the Y direction. In this embodiment, the angle formed by the second inclined portion 65 and the Y direction is defined as θ2. θ2 is a value smaller than 90 degrees.

[0042] The upstream guide 70 has a second convex portion 71 having a convex portion downstream end 72 that is the most downstream in the conveying direction, and a second base portion 77 that is located upstream of the convex portion downstream end 72. The third inclined portion 73 and the base portion downstream end 78 are parallel to the Y direction. The base portion downstream end 78 of the second base portion 77 that is the most downstream in the conveying direction is located upstream of the convex portion downstream end 72.

[0043] The second convex portion 71 has a third inclined portion 73 having a convex portion downstream end 72 and a fourth inclined portion 75 disposed between the third inclined portion 73 and the second base portion 77. The inclined downstream end 76, which is the downstream end of the fourth inclined portion 75 in the conveying direction, is inclined with respect to the Y direction when viewed from directions perpendicular to both the conveying direction and the Y direction. The inclined downstream end 76 of the fourth inclined portion 75 inclines from the center to the end in the Y direction from the upstream side to the downstream side in the conveying direction. In the end passing region R1, the inclined downstream end 76 of the fourth inclined portion 75 is located more downstream in the conveying direction as the distance from the center to the negative Y direction increases among multiple different positions in the Y direction. In this embodiment, the angle formed between the second inclined portion 65 and the Y direction is defined as θ1. θ1 is equal to θ2 and is less than 90 degrees. θ1 and θ2 are preferably 45 degrees or less.

[0044] The second convex portion 71 of the upstream guide 70 and the first convex portion 61 of the downstream guide 60 overlap in the conveying direction by a distance D0 in the conveying direction between the convex portion downstream end 72 and the convex portion upstream end 62. The first base portion 67 and the second convex portion 71 are arranged at a first distance, and the first inclined portion 63 and the second base portion 77 are arranged at a second distance. It is preferable that the first distance and the second distance are the same.

[0045] The downstream guide 60 has a second inclined portion 65, and the upstream guide 70 has a fourth inclined portion 75. The second inclined portion 65 and the fourth inclined portion 75 intersect with the conveying direction and form the same angle with the Y direction. Therefore, a gap 90 between the second inclined portion 65 and the fourth inclined portion 75 is not parallel to the conveying direction. Therefore, the distance that the leading edges of both ends of the paper pass through the gap 90 is shorter than when the gap 90 is parallel to the conveying direction, making it difficult for the paper to get caught in the gap 90. Furthermore, because the overlapping portion between the second inclined portion 65 and the fourth inclined portion 75 has a predetermined length in the Y direction, even if the paper is conveyed with a deviation in the first direction, the deviation can be tolerated by a predetermined length.

[0046] FIG. 7 is a cross-sectional view taken along line AA in FIG. 6. Referring to FIG. 7, the third inclined portion 73 of the upstream guide 70 has an upstream inclined surface M3 that forms part of the conveying path. The first base portion 67 of the downstream guide 60 faces the third inclined portion 73 of the upstream guide 70. The first base portion 67 of the downstream guide 60 has a base surface M4 that forms part of the conveying path. In the cross section, the upstream inclined surface M3 and the base surface M4 intersect at an angle θa. The angle θa is smaller than 90 degrees. Therefore, even if the leading edge of a sheet of paper conveyed along the conveying path while in contact with the upstream inclined surface M3 abuts against the base surface M4, the leading edge of the sheet slides along the base surface M4 and is guided toward the conveying path. Furthermore, a force can be applied to the sheet in a direction that corrects the curvature of the sheet.

[0047] The upstream foundation edge 68, which is the most upstream of the first foundation portion 67, and the downstream convex edge 72, which is the most downstream of the second convex portion 71, are separated by a distance D1a in a direction parallel to the upstream inclined surface M3. The upstream foundation edge 68 is also separated by a distance D2a from the upstream inclined surface M3 in a direction perpendicular to the upstream inclined surface M3. Because the distance D2a is greater than the distance D1a, the leading edge of the paper edge is less likely to enter upstream of the upstream foundation edge 68.

[0048] FIG. 8 is a cross-sectional view taken along line BB in FIG. 6. Referring to FIG. 8, the second base portion 77 of the upstream guide 70 has an upstream inclined surface M3 that forms part of the conveying path. The first inclined portion 63 of the downstream guide 60 faces the second base portion 77 of the upstream guide 70. The first inclined portion 63 of the downstream guide 60 has an inclined surface M6 that forms part of the conveying path. In the cross section, the upstream inclined surface M3 and the inclined surface M6 are parallel and do not intersect. Here, the angle θb between the upstream inclined surface M3 and the inclined surface M6 is set to 0 degrees. Therefore, the leading edge of a sheet of paper conveyed along the conveying path while in contact with the upstream inclined surface M3 is less likely to come into contact with the inclined surface M6. Even if the leading edge does come into contact with the inclined surface M6, the leading edge slides along the inclined surface M6 and is guided toward the conveying path.

[0049] The upstream convex end 62, which is the most upstream of the first inclined portion 63, and the downstream foundation end 78, which is the most downstream of the second foundation portion 77, are separated by a distance D1d in a direction parallel to the upstream inclined surface M3. The upstream convex end 62 is also separated by a distance D2d from the upstream inclined surface M3 in a direction perpendicular to the upstream inclined surface M3. Because the distance D2d is greater than the distance D2a, the leading edge of the paper edge is less likely to enter upstream of the upstream convex end 62.

[0050] FIG. 9 is a cross-sectional view taken along line CC in FIG. 6. Referring to FIG. 9, the fourth inclined portion 75 of the upstream guide 70 has an upstream inclined surface M3 that forms part of the conveying path. The second inclined portion 65 of the downstream guide 60 faces the fourth inclined portion 75 of the upstream guide 70. The second inclined portion 65 of the downstream guide 60 has a twisted surface M5 that forms part of the conveying path. In the cross-section, the upstream inclined surface M3 and the twisted surface M5 intersect at an angle θc. The angle θc is smaller than the angle θa and larger than the angle θb. Therefore, even if the leading edge of a sheet of paper conveyed along the conveying path while in contact with the upstream inclined surface M3 abuts against the twisted surface M5, the leading edge of the sheet slides along the twisted surface M5 and is guided toward the conveying path.

[0051] The most upstream inclined downstream edge 76 of the fourth inclined section 75 and the most downstream inclined upstream edge 66 of the second inclined section 65 are separated by a distance D1c in a direction parallel to the upstream inclined surface M3. The inclined upstream edge 66 is also separated by a distance D2c from the upstream inclined surface M3 in a direction perpendicular to the upstream inclined surface M3. Because the distance D2c is greater than the distance D1c, the leading edge of the edge of the paper is less likely to enter upstream of the inclined upstream edge 66.

[0052] Figure 10 is a cross-sectional view taken along line DD in Figure 6. Referring to Figure 10, in the cross section, upstream inclined surface M3 and twisted surface M5 intersect at angle θd. Angle θd is smaller than angle θc and larger than angle θb. Therefore, even if the leading edge of a sheet of paper being transported along the transport path while in contact with upstream inclined surface M3 abuts against twisted surface M5, the leading edge of the sheet of paper slides along twisted surface M5 and is guided in the direction of the transport path.

[0053] The most upstream inclined downstream edge 76 of the fourth inclined section 75 and the most downstream inclined upstream edge 66 of the second inclined section 65 are separated by a distance D1d in a direction parallel to the upstream inclined surface M3. The inclined upstream edge 66 is also separated by a distance D2d from the upstream inclined surface M3 in a direction perpendicular to the upstream inclined surface M3. Because the distance D2d is greater than the distance D1d, the leading edge of the edge of the paper is less likely to enter upstream of the inclined upstream edge 66.

[0054] Figure 11 is a cross-sectional view taken along line EE in Figure 6. Referring to Figure 11, in the cross section, upstream inclined surface M3 and twisted surface M5 intersect at angle θe. Angle θe is smaller than angle θd and larger than angle θb. Therefore, even if the leading edge of a sheet of paper being conveyed along the conveyance path while in contact with upstream inclined surface M3 abuts against twisted surface M5, the leading edge of the sheet of paper slides along twisted surface M5 and is guided in the direction of the conveyance path.

[0055] The most upstream inclined downstream edge 76 of the fourth inclined section 75 and the most downstream inclined upstream edge 66 of the second inclined section 65 are separated by a distance D1e in a direction parallel to the upstream inclined surface M3. The inclined upstream edge 66 is also separated by a distance D2e from an upstream inclined surface M3 that is perpendicular to the upstream inclined surface M3. Because the distance D2e is greater than the distance D1e, the leading edge of the edge of the paper is less likely to enter upstream of the inclined upstream edge 66.

[0056] As described above, the image forming apparatus 1 in this embodiment includes a downstream guide 60 (first guide portion) that forms part of a paper transport path and extends in the Y direction (first direction) intersecting the transport direction. The downstream guide 60 has a first base portion 67 and a first convex portion 61 that protrudes upstream of the first base portion 67 in the transport direction. The first convex portion 61 has a first inclined portion 63 having a convex portion upstream end 62 that is the most upstream in the transport direction, and a second inclined portion 65 that is disposed between the first inclined portion 63 and the first base portion 67. The upstream end of the second inclined portion 65 intersects with the Y direction when viewed from a direction perpendicular to both the transport direction and the Y direction. Therefore, when paper is transported in a curved state, the leading edge of the paper can abut against the second inclined portion 65 of the first convex portion 61. Therefore, the leading edge of the paper moves along the second inclined portion 65, thereby preventing the paper from getting caught behind the downstream guide 60.

[0057] The second inclined section 65 also has a twisted surface M5 that forms part of the conveying path, and in a cross section normal to the Y direction, the angles θc, θd, and θe that the twisted surface M5 makes with the upstream inclined surface M3 are less than 90 degrees. Therefore, when the leading edge of a sheet of paper conveyed in the conveying direction abuts against the twisted surface M5, the leading edge of the sheet moves along the twisted surface M5. This allows the leading edge of the sheet to move in the conveying direction, thereby preventing the sheet from jamming. Furthermore, a force can be applied to the sheet in a direction that corrects the curvature of the sheet.

[0058] The first base portion 67 has a base surface M4 that forms part of the conveying path, and the first inclined portion 63 has an inclined surface M6 that forms part of the conveying path, with the base surface M4 and the inclined surface M6 parallel to the Y direction and intersecting the conveying direction, and in a cross section normal to the Y direction, a first angle θa that the base surface M4 makes with the conveying direction is greater than a second angle θb that the inclined surface M6 makes with the conveying direction, and the second inclined portion 65 has a twisted surface M5 that connects the base surface M4 and the inclined surface M6. This allows for deviation of the conveyed paper in the Y direction up to the Y length of the second inclined portion 65.

[0059] Additionally, the inclined upstream end 66 of the second inclined portion 65 is inclined from the center to the end in the Y direction, from the downstream side to the upstream side in the transport direction. Therefore, when the leading edge of the paper contacts the second inclined portion 65, a force can be applied in a direction toward the center in the Y direction. This makes it possible to prevent the recording medium from jamming.

[0060] The second inclined portion 65 is disposed at a position where the edge of the paper passes in the Y direction. Therefore, the leading edges of both ends of the paper can be brought into contact with the second inclined portion 65.

[0061] The image forming apparatus 1 further includes an upstream guide 70 that is disposed upstream of the downstream guide 60 in the transport direction, forms part of the transport path, and extends in the Y direction, and the upstream guide 70 has a second convex portion 71 that is spaced a first distance from the first base portion 67 in the transport direction, and a second base portion 77 that is spaced a second distance from the first convex portion 61 in the transport direction. This allows the upstream guide 70 to move relative to the downstream guide 60, and can prevent paper from jamming by being curved to a degree corresponding to the larger of the first distance and the second distance.

[0062] <Summary of implementation form> (Item 1) A first guide portion that forms a part of a transport path for the recording medium and extends in a first direction that intersects with the transport direction, the first guide portion has a first base portion and a first protrusion portion that protrudes upstream of the first base portion in the conveying direction, the first convex portion has a first inclined portion having an upstream end of the first convex portion that is located most upstream in the conveying direction, and a second inclined portion that is disposed between the first inclined portion and the first base portion, an upstream end of the second inclined portion intersects with the first direction when viewed from a direction perpendicular to both the transport direction and the first direction;

[0063] According to this aspect, the first guide section includes a first base section and a first convex section and a first base section protruding from the first base section toward the upstream side in the conveying direction. The first convex section includes a first inclined section and a second inclined section, and the upstream end of the second inclined section is inclined from the first direction when viewed from a direction perpendicular to both the conveying direction and the first direction. Therefore, even when the recording medium is conveyed in a curved state, the leading edge of the recording medium can abut against the second inclined section of the first convex section. Therefore, the leading edge of the recording medium moves along the second inclined section, thereby preventing the recording medium from getting stuck behind the first guide section. As a result, an image forming apparatus that prevents recording medium jams can be provided.

[0064] (Item 2) The image forming device described in Item 1, wherein the second inclined portion has an inclined surface that forms part of the transport path, and in a cross section normal to the first direction, the angle that the inclined surface makes with the transport direction is less than 90 degrees.

[0065] According to this aspect, the angle that the inclined surface makes with the transport direction in a cross section normal to the first direction is less than 90 degrees. Therefore, when the leading edge of a recording medium transported in the transport direction abuts against the inclined surface, the leading edge of the recording medium moves along the inclined surface. This allows the leading edge of the recording medium to move in the transport direction. This prevents the recording medium from jamming. Furthermore, a force can be applied to the recording medium in a direction that corrects the curvature of the recording medium.

[0066] (Item 3) The first base portion has a base surface that forms a part of the transport path, the first inclined portion has an inclined surface that forms a part of the transport path, the base surface and the inclined surface are parallel to the first direction and intersect with the conveying direction; In a cross section normal to the first direction, a first angle formed by the base surface with respect to the conveying direction is larger than a second angle formed by the first inclined surface with respect to the conveying direction, 3. The image forming apparatus according to item 1 or 2, wherein the second inclined portion has a twisted surface that connects the base surface and the inclined surface.

[0067] According to this aspect, deviation of the conveyed recording medium in the first direction can be tolerated up to the length of the second inclined portion in the first direction.

[0068] (Item 4) The image forming apparatus according to any one of Items 1 to 3, wherein the upstream end of the second inclined portion is inclined from the center to the end in the first direction from the downstream side to the upstream side in the transport direction.

[0069] According to this aspect, when the leading edge of the recording medium abuts against the second inclined portion, a force can be applied in the first direction toward the center, thereby preventing the recording medium from becoming jammed.

[0070] (Item 5) The image forming apparatus according to any one of Items 1 to 4, wherein the second inclined portion is disposed at a position where an edge of the recording medium passes in the first direction.

[0071] According to this aspect, the leading ends of both ends of the recording medium can be brought into contact with the second inclined portions.

[0072] (Item 6) The conveying device further includes a second guide portion that is disposed upstream of the first guide portion in the conveying direction, forms a part of the conveying path, and extends in the first direction, 6. An image forming apparatus according to any one of items 1 to 5, wherein the second guide portion has a second convex portion spaced a first distance from the first base portion in the transport direction, and a second base portion spaced a second distance from the first convex portion in the transport direction.

[0073] According to this aspect, the second guide section is disposed upstream of the first guide section in the transport direction. The second guide section is disposed at a first distance or a second distance from the first guide section in the transport direction. This allows the second guide section to move relative to the first guide section, and prevents the recording medium from becoming clogged by a degree corresponding to the larger of the first distance or the second distance.

[0074] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0075] 1 image forming apparatus, 3 image forming section, 4 paper feed section, 7 operation panel, 10 housing, 11 side door, 20Y, 20M, 20C, 20K image forming unit, 21Y exposure device, 22Y charging roller, 23Y photosensitive drum, 24Y developing device, 25Y primary transfer roller, 26 secondary transfer roller, 30 intermediate transfer belt, 31 timing roller, 31A main roller, 31B sub-roller, 33 drive roller, 34 driven roller, 35 paper feed cassette, 35A manual feed cassette, 36, 36A take-out roller, 37, 37A, 37B paper feed roller, 38 paper discharge roller, 39 paper discharge tray, 41 main transport path, 43 reversing path, 51 fixing device, 60 downstream guide, 61 first convex portion, 62 upstream end of convex portion, 63 First inclined portion, 65 second inclined portion, 66 inclined upstream end, 67 first base portion, 68 upstream end of base portion, 70 upstream guide, 71 second convex portion, 72 downstream end of convex portion, 73 third inclined portion, 75 fourth inclined portion, 76 inclined downstream end, 77 second base portion, 78 downstream end of base portion, 80 inner guide, 81 outer guide, L1 to L4, R1 to R4 end passing area, M1 outer surface, M2 inner surface, M3 upstream inclined surface, M4 base surface, M5 twisted surface, M6 inclined surface, M7 lower surface, M8 upper surface.

Claims

1. a first guide portion that forms a part of a transport path for the recording medium and extends in a first direction that intersects with the transport direction; the first guide portion has a first base portion and a first protrusion portion that protrudes upstream in the conveying direction from the first base portion, the first convex portion has a first inclined portion having an upstream end of the first convex portion that is located most upstream in the conveying direction, and a second inclined portion that is disposed between the first inclined portion and the first base portion, an upstream end of the second inclined portion intersects with the first direction when viewed from a direction perpendicular to both the transport direction and the first direction;

2. the second inclined portion has an inclined surface that forms a part of the transport path, 2. The image forming apparatus according to claim 1, wherein an angle formed by the inclined surface and the conveying direction in a cross section normal to the first direction is smaller than 90 degrees.

3. the first base portion has a base surface that forms a part of the transport path; the first inclined portion has an inclined surface that forms a part of the transport path, the base surface and the inclined surface are parallel to the first direction and intersect with the conveying direction; In a cross section normal to the first direction, a first angle formed by the base surface with respect to the conveying direction is larger than a second angle formed by the inclined surface with respect to the conveying direction, The image forming apparatus according to claim 1 , wherein the second inclined portion has a twisted surface connecting the base surface and the inclined surface.

4. 4. The image forming apparatus according to claim 1, wherein the upstream end of the second inclined portion is inclined from the center to the end in the first direction from the downstream side to the upstream side in the transport direction.

5. 4. The image forming apparatus according to claim 1, wherein the second inclined portion is disposed at a position where an edge of the recording medium passes in the first direction.

6. a second guide portion that is disposed upstream of the first guide portion in the conveying direction, forms a part of the conveying path, and extends in the first direction; An image forming apparatus as described in any one of claims 1 to 3, wherein the second guide portion has a second convex portion spaced a first distance from the first base portion in the transport direction, and a second base portion spaced a second distance from the first convex portion in the transport direction.

Images