JP5663508B2 - Sheet conveying apparatus and image forming apparatus including the same - Google Patents

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet, and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, there is a known problem that a sheet to be conveyed is skewed in a sheet conveying apparatus for conveying a sheet. When the sheet is skewed, the sheet is conveyed with the side edge of the sheet inclined with respect to the sheet conveying direction. When the sheet conveying apparatus is mounted on an image forming apparatus that forms an image on a sheet, the skew of the sheet causes an inclination of the image formed on the sheet. In order to correct such skew of the sheet, in the techniques described in Patent Documents 1 and 2, a pair of registration rollers is disposed in the sheet conveyance path. In the skewed state, the leading edge of the sheet conveyed from the upstream side in the conveying direction is abutted against the registration roller pair in a state where the rotation is stopped. At this time, the sheet is bent, and then the registration roller pair rotates to correct the skew of the sheet.

Japanese Patent Application Laid-Open No. 07-10324 JP 2005-162381 A

  In an image forming apparatus, a sheet is often conveyed from a plurality of sheet conveyance paths toward an image forming unit that forms an image. Examples of such a sheet conveyance path include a sheet conveyance path extending from a sheet cassette in which sheets are stored in advance, a sheet conveyance path extending from a manual feed tray, and the like. In the techniques described in Patent Documents 1 and 2, such a sheet conveyed from a plurality of sheet conveyance paths moves in a direction intersecting the sheet conveyance direction in order to accurately enter the nip portion of the registration roller pair. Possible guide members are arranged.

  However, as described above, when a movable guide member is disposed on the upstream side of the registration roller pair, the structure of the sheet conveying apparatus is complicated and the apparatus main body is enlarged.

  The present invention has been made in view of the above problems, and in a sheet conveying apparatus in which a sheet is conveyed from a plurality of sheet conveying paths toward a pair of registration rollers, skewing of the sheet is suitably corrected, It is an object of the present invention to provide a sheet conveying apparatus that realizes downsizing of the apparatus and an image forming apparatus including the sheet conveying apparatus.

A sheet conveying apparatus according to an aspect of the present invention includes a casing, a first sheet conveying path that is disposed in the casing and that conveys a first sheet, the second sheet is disposed in the casing, and A second sheet conveying path that is conveyed, a first roller that is disposed in the first sheet conveying path and that forms a first nip portion between the first roller and the first roller. A second registration roller, which is composed of a pair of registration rollers, a third roller disposed in the second sheet conveyance path, and forming a second nip portion between the second roller and the second roller. A surface of the first and third rollers is made of an elastic material, and the surface of the second roller has a higher hardness and lower than the surfaces of the first and third rollers. or a metal material or a resin material having a coefficient of friction Characterized in that configured.

According to this configuration, in the first sheet conveyance path where the first sheet is conveyed and the second sheet conveyance path where the second sheet is conveyed, the second roller constituting each nip portion is commonly used. The Therefore, the size reduction of the sheet conveying apparatus including a plurality of sheet conveying paths is realized. In addition, the cost of the apparatus can be reduced by sharing the second roller having a higher hardness and a lower friction coefficient (higher slidability) than the first and third rollers. . Moreover, the cost reduction of an apparatus is implement | achieved by sharing the 2nd roller which consists of a metal material or a resin material.

In the above configuration, the surface of the first and third rollers, it is preferable that consists of a rubber material.

According to this configuration, the nip portion where the sheet is conveyed is suitably formed between the surfaces of the first and third rollers made of a rubber material and the surface of the second roller made of a metal material or a resin material. that.

  Said structure WHEREIN: It has further the drive part which rotationally drives the said 2nd roller to the periphery of a roller axis | shaft, The said drive part has the front-end | tip part of the said 1st sheet or the said 2nd sheet, and rotation of the said 2nd roller Preferably, the second roller is driven to rotate after contacting the first nip portion or the second nip portion in a stopped state.

  According to this configuration, the second roller is driven to rotate after the leading end of the first sheet or the second sheet comes into contact with the first nip or the second nip. Therefore, even when the sheet is skewed, the leading edge of the first sheet or the second sheet is conveyed downstream in the sheet conveying direction in a state perpendicular to the sheet conveying direction. The

  In the above configuration, the driving unit rotates the second roller around the roller axis in a first direction and a second direction opposite to the first direction. In the first state, the first sheet passes through the first nip portion, in the first direction, and in the second state, the second sheet passes through the second nip portion, the second direction. Further, it is preferable that the second roller is rotationally driven.

  According to this configuration, the conveyance direction of the first sheet and the second sheet when passing through the first nip portion and the second nip portion is set in the same direction.

  In the above configuration, it is preferable that the first and third rollers are rotated following the second roller.

  According to this configuration, it is possible to rotationally drive the first, second, and third rollers by providing one drive unit.

  In the above configuration, the first sheet conveyance path is upstream of the first nip portion in the sheet conveyance direction and faces the first sheet surface that is in contact with the first roller of the first sheet. A second conveying wall disposed upstream of the first sheet conveying path and upstream of the first nip portion of the first sheet conveying path in a sheet conveying direction, the second conveying sheet being in contact with the second roller of the first sheet. A second conveying wall disposed to face the sheet surface, wherein the first conveying wall intersects the first wall surface disposed upstream of the sheet conveying direction and the first wall surface. A second surface connected to the first wall surface and extending to the vicinity of the first roller, and a boundary between the first wall surface and the second wall surface, In the cross-sectional view including the sheet conveyance direction of the first sheet, the first sheet conveyance path And a terminal end of the second conveying wall is disposed to face the peripheral surface of the second roller, and passes through the bent top in the cross-sectional view. It is preferable that the 1st straight line which contact | connects the said terminal part of the said 2nd conveyance wall of the said sheet conveyance direction downstream rather than a top part cross | intersects the surrounding surface of a said 2nd roller.

  According to this configuration, the first sheet conveyance path includes the first conveyance wall and the second conveyance wall. The first conveying wall faces the first sheet surface that is in contact with the first roller. The second transport wall is opposed to the second sheet surface that is in contact with the second roller. The first transfer wall includes a first wall surface, a second wall surface, and a bent top portion. The bent top portion protrudes toward the first sheet conveyance path and corresponds to a boundary portion between the first wall surface and the second wall surface. The leading edge of the first sheet is detached from the terminal end of the second conveying wall while the first sheet conveyed on the first sheet conveying path is in contact with the bent top of the first conveying wall. At this time, the leading end portion of the first sheet is brought into contact with the peripheral surface of the second roller. Therefore, the leading edge of the first sheet comes into contact with the peripheral surface of the second roller, which has higher slidability than the first and third rollers, so that the leading edge of the first sheet is smoothly guided to the first nip. It is burned.

  In the above configuration, an angle formed by the tangent line of the second roller and the first straight line at a first outer peripheral point where the first straight line intersects the peripheral surface of the second roller is set to 60 degrees or less. It is preferred that

  According to this configuration, the leading edge of the first sheet is detached from the terminal end of the second conveying wall while the first sheet conveyed through the first sheet conveying path is in contact with the bent top of the first conveying wall. The At this time, the leading end portion of the first sheet is brought into contact with the peripheral surface between the first outer peripheral point of the second roller and the first nip portion. And the angle which the tangent of the 2nd roller in a 1st outer peripheral point and a 1st straight line make is set to 60 degrees or less. Therefore, the impact when the leading edge of the first sheet contacts the peripheral surface of the second roller is suppressed, and scratches and wrinkles are unlikely to occur at the leading edge of the first sheet.

  Said structure WHEREIN: It is preferable that a said 2nd conveyance wall is provided with the 1st curved part which curved to the concave shape with respect to the said 1st sheet conveyance path facing the said 2nd wall surface.

  According to this configuration, the second transport wall includes the first curved portion at a position facing the second wall surface of the first transport wall. When the leading edge of the first sheet is detached from the terminal end of the second transport wall, the first sheet is placed on the second transport wall between the terminal end of the second transport wall and the bent top of the first transport wall. A slight loop of convex shape is formed. And the said 1st curved part is arrange | positioned at the 2nd conveyance wall side of this loop part. When the leading end portion of the first sheet comes into contact with the first nip portion and stops, the loop portion is further grown on the first bending portion side, and a loop along the first bending portion is preferable for the first sheet. Formed.

  In the above configuration, the first sheet is disposed between the first sheet conveyance path and the second sheet conveyance path in a cross-sectional view including the sheet conveyance direction of the first sheet, and conveys the third sheet to the first nip portion. It is preferable to provide a third sheet conveyance path.

  According to this configuration, the third sheet conveyance path can be disposed between the first sheet conveyance path and the second sheet conveyance path.

  In the above configuration, the third sheet conveyance path is upstream of the first nip portion of the third sheet conveyance path in the sheet conveyance direction and is in contact with the first roller of the third sheet. A third conveying wall disposed to face the third sheet surface; and the second sheet of the third sheet upstream of the first nip portion of the third sheet conveying path in the sheet conveying direction. A fourth transport wall disposed so as to face the fourth sheet surface in contact with the roller, and the third transport wall is a plane extending toward the peripheral surface of the second roller It is preferable that

  According to this configuration, the third sheet conveyance path includes a third conveyance wall disposed to face the third sheet surface of the third sheet that is in contact with the first roller, and the third sheet. A fourth conveying wall disposed so as to face the fourth sheet surface in contact with the second roller. A 3rd conveyance wall consists of a plane extended toward the surrounding surface of a 2nd roller. The third sheet conveyed through the third sheet conveyance path is guided by the third conveyance wall and is brought into contact with the peripheral surface of the second roller. For this reason, the leading edge of the third sheet comes into contact with the peripheral surface of the second roller, which is more slidable than the first and third rollers, so that the leading edge of the third sheet smoothly enters the first nip. Led.

  Said structure WHEREIN: The 1st extended straight line which extended the said 3rd conveyance wall to the surrounding surface of the said 2nd roller, and the tangent of the said 2nd roller in the intersection of the said 1st extended straight line and the surrounding surface of the said 2nd roller Is preferably set to 50 degrees or less.

  According to this structure, the 3rd sheet conveyed by the 3rd sheet conveyance path is guided to the 3rd conveyance wall, and is contact | abutted to the surrounding surface of a 2nd roller. At this time, the leading end portion of the third sheet comes into contact with the peripheral surface of the second roller at an angle of 50 degrees or less. Therefore, the impact when the leading end of the third sheet contacts the peripheral surface of the second roller is suppressed, and scratches and wrinkles are unlikely to occur at the leading end of the third sheet.

  Said structure WHEREIN: It is preferable that a said 4th conveyance wall is provided with the 2nd curved part curved in the concave shape with respect to the said 3rd sheet | seat conveyance path.

  According to this configuration, the fourth transport wall includes the second curved portion having a concave shape with respect to the third sheet transport path. When the leading edge of the third sheet leaves the terminal end of the third conveyance wall and comes into contact with the first nip, the third sheet forms a slight convex loop toward the fourth conveyance wall. ing. And the said 2nd bending part is arrange | positioned at the 4th conveyance wall side of this loop. When the leading end portion of the third sheet stops at the first nip portion, the loop grows on the second curved portion side, and a loop along the second curved portion is suitably formed on the third sheet.

  An image forming apparatus according to another aspect of the present invention includes a sheet conveying apparatus according to any one of the above, a sheet cassette in which the first sheet is accommodated and supplying a sheet to the first sheet conveying path, and the first A tray on which three sheets are placed, and a sheet that is supplied to the third sheet conveyance path; an image forming unit that forms an image on the first sheet or the third sheet that has passed through the first nip portion; After reversing the front and back of the first sheet or the third sheet on which the image is formed in the image forming unit, the first sheet or the third sheet with the front and back reversed, as the second sheet, And a second sheet conveying path that conveys toward the image forming unit.

  According to this configuration, the first sheet stored in the sheet cassette passes through the first nip portion from the first sheet conveyance path and is guided to the image forming portion. Further, the third sheet placed on the tray passes through the first nip portion from the third sheet conveyance path and is guided to the image forming portion. Furthermore, in the image forming unit, the first or third sheet on which the image is formed on the surface passes through the second nip portion from the second conveyance path as the second sheet, and is guided again to the image forming unit. Therefore, in the image forming apparatus, the first sheet conveyance path extending from the sheet cassette, the third sheet conveyance path extending from the tray, and the second sheet conveyance path for duplex printing are merged. Is possible. At this time, the rollers constituting the registration roller pair can be shared. As a result, it is possible to reduce the size of the joining portion where the plurality of sheet conveying paths are joined. In addition, the cost of the apparatus can be reduced by sharing the second roller having higher hardness and higher slidability than the first and third rollers.

  In the above configuration, a guide member having a guide surface that guides the second sheet that has passed through the second nip portion toward the image forming portion, and a tangent line of the second roller in the second nip portion, It is preferable that the guide member intersects with the guide surface.

  According to this configuration, in the image forming unit, the first or third sheet on which the image is formed passes through the second nip portion from the second conveyance path as the second sheet, and again, the image forming unit Led to. The guide member has a guide surface and guides the second sheet that has passed through the second nip portion toward the image forming portion. When passing through the second nip portion, the second sheet comes into contact with the guide member at a predetermined angle. Therefore, an image is formed on the surface, and it is possible to suitably correct the curvature of the second sheet that is likely to be curled.

  According to the present invention, in a sheet conveying apparatus in which a sheet is conveyed from a plurality of sheet conveying paths toward a pair of registration rollers, sheet skew is suitably corrected and the apparatus is reduced in size. An apparatus and an image forming apparatus including the apparatus are provided.

1 is an internal cross-sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an internal cross-sectional view of the sheet conveying apparatus according to the embodiment of the present invention. 1 is an enlarged cross-sectional view of a sheet conveying device according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a state of a sheet conveyed on a first conveyance path in a sheet conveyance apparatus. FIG. 4 is a diagram illustrating a state of a sheet conveyed on a first conveyance path in a sheet conveyance apparatus. FIG. 4 is a diagram illustrating a state of a sheet conveyed on a first conveyance path in a sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed through a second conveyance path in the sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed through a second conveyance path in the sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed through a second conveyance path in the sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed on a third conveyance path in the sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed on a third conveyance path in the sheet conveyance apparatus. FIG. 6 is a diagram illustrating a state of a sheet conveyed on a third conveyance path in the sheet conveyance apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an internal cross-sectional view of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 shown in FIG. 1 is a so-called color printer, but in other embodiments, the image forming apparatus forms a monochrome printer, a facsimile machine, a multifunction machine having these functions, and an image on a sheet. Other devices may be used. Note that the terms used in the following description, such as “up”, “down”, “front”, “rear”, “left” and “right”, are merely for the purpose of clarifying the description. There is no limitation on the principle of the image forming apparatus. Further, in the following description, the term “sheet” means copy paper, coated paper, OHP sheet, cardboard, postcard, tracing paper, other sheet material subjected to image forming processing, or any processing other than image forming processing. Means the sheet material to receive.

  The image forming apparatus 1 includes a main body housing 10 having a substantially rectangular parallelepiped shape. The body housing 10 has a cross-sectional shape defined by an upper surface portion 101, a lower surface portion 102, a right side portion 103, and a left side portion 104. A first caster 105 and a second caster 106 are disposed on the lower surface portion 102 so that the image forming apparatus 1 can move on the installation surface. The image forming apparatus 1 includes a manual feed tray 130 and a discharge tray 480 that protrude from the main body housing 10 in the right direction.

  The manual feed tray 130 is disposed at the center of the right side portion 103 in the vertical direction. The manual feed tray 130 can be attached to and detached from the main body housing 10. When the manual feed tray 130 is disposed so as to protrude to the right of the main body housing 10, the user can place a sheet on the manual feed tray 130. The sheet on the manual feed tray 130 is drawn into the main body housing 10 based on an instruction input by a user through an operation unit (not shown), is subjected to image formation processing, and is discharged to the discharge tray 480.

  The discharge tray 480 is an upper end portion of the right side portion 103 and is disposed at a position above the manual feed tray 130. A sheet subjected to the image forming process is discharged to the discharge tray 480.

  Further, referring to FIG. 1, the image forming apparatus 1 has a first conveyance path 121, a second conveyance path 131, a merging conveyance section 500, and a third conveyance path 460 as sheet conveyance paths for conveying sheets. An image forming conveyance path 145, a drying conveyance path 155, an upper conveyance path 200, a horizontal conveyance path 400, a reverse conveyance path 302, a return conveyance path 303, and a discharge conveyance path 450. Further, the image forming apparatus 1 includes a cassette 120, an ink head unit 20, a conveyance belt 140, and a drying belt 150.

  The cassette 120 accommodates the sheet P inside. The cassette 120 can be pulled out from the main body housing 10 in the front direction (the front side in FIG. 1). The sheet P accommodated in the cassette 120 is sent upward in the main body housing 10. Thereafter, the sheet P is subjected to an image forming process in the main body housing 10 based on an instruction input by the user, and is discharged to the discharge tray 480. The cassette 120 includes a lift plate (not shown) that supports the sheet P. The lift plate is inclined so as to push up the leading edge (right end) of the sheet P upward. The sheet P accommodated in the cassette 120 is conveyed to the first conveyance path 121.

  The first conveyance path 121 is a sheet conveyance path disposed upward from the cassette 120. In the first transport path 121, a first pickup roller 122, a first paper feed roller pair 123, a first transport roller pair 124, and a second transport roller pair 125 are disposed.

  The first pickup roller 122 is arranged on the leading edge of the sheet P pushed upward by the lift plate. When the first pickup roller 122 rotates, the sheet P is pulled out from the cassette 120.

  The first paper feed roller pair 123 is disposed downstream of the first pickup roller 122 in the sheet conveyance direction. The first paper feed roller pair 123 sends the sheet P further downstream. The first transport roller pair 124 and the second transport roller pair 125 are disposed on the downstream side of the first paper feed roller pair 123 in the sheet transport direction. The first transport roller pair 124 and the second transport roller pair 125 transport the sheet P sent out by the first paper feed roller pair 123 further downstream (upward). The sheet P transported upward by the second transport roller pair 125 is transported to the merging transport unit 500.

  The converging conveyance unit 500 is a downstream portion of the first conveyance path 121, the second conveyance path 131, and the third conveyance path 460 in the sheet conveyance direction, and includes the first conveyance path 121, the second conveyance path 131, and the third conveyance path. 460 corresponds to the part where the merging occurs. The merging / conveying unit 500 includes a third conveying roller pair 126, a fourth conveying roller pair 134, a sixth conveying roller pair 462, and a registration roller unit 50 including three rollers. The sheet P transported on the first transport path 121 by the second transport roller pair 125 is transported further downstream by the third transport roller pair 126 and the registration roller unit 50. The merging and conveying unit 500 will be described in detail later.

  The second conveyance path 131 is a sheet conveyance path disposed to the left from the manual feed tray 130. In the second transport path 131, a second pickup roller 132, a second paper feed roller pair 133, and a fourth transport roller pair 134 are disposed.

  The second pickup roller 132 is disposed on the leading edge of the sheet P placed on the manual feed tray 130. When the second pickup roller 132 rotates, the sheet P is pulled out from the manual feed tray 130.

  The second paper feed roller pair 133 is disposed downstream of the second pickup roller 132 in the sheet conveyance direction. The second paper feed roller pair 133 sends the sheet P further downstream. The sheet P conveyed leftward by the second paper feed roller pair 133 is conveyed to the merging conveyance unit 500. The sheet P transported on the second transport path 131 by the second paper feed roller pair 133 is transported further downstream by the fourth transport roller pair 134 and the registration roller unit 50.

  The image forming conveyance path 145 and the drying conveyance path 155 are arranged on the downstream side in the sheet conveyance direction with respect to the merging conveyance section 500, and convey the sheet P substantially horizontally toward the left. In the image forming conveyance path 145, the ink head unit 20 and the conveyance belt 140 are disposed to face each other. A drying belt 150 is disposed in the drying conveyance path 155.

  The ink head unit 20 atomizes the ink and sprays the ink directly on the sheet P according to the formed image. The ink head unit 20 includes a yellow head 20Y, a magenta head 20M, a cyan head 20C, and a black head 20Bk, and uses yellow, magenta, cyan, and black inks, respectively. A known piezo-type or thermal-type ink head is applied to the ink head unit 20.

  The conveyor belt 140 extends in the left-right direction so as to face the ink head unit 20. The conveyor belt 140 is spanned by a first driven roller 141, a second driven roller 142, a first drive roller 143, and a third driven roller 144, respectively. The first driving roller 143 is rotationally driven by a driving unit (not shown), so that the transport belt 140 is rotated counterclockwise. The upper surface (transport surface) of the transport belt 140 forms an image forming transport path 145. The sheet P that has passed through the merging conveyance unit 500 is conveyed on the image forming conveyance path 145 while being carried on the conveyance belt 140, and an image is formed on the sheet P by the ink head unit 20.

  The drying belt 150 is disposed on the downstream side of the conveyance belt 140 in the sheet conveyance direction. An upper surface of the drying belt 150 forms a drying conveyance path 155. The drying belt 150 is stretched in the left-right direction by the fourth driven roller 151 and the second drive roller 152. The second driving roller 152 is rotationally driven by a driving unit (not shown), so that the drying belt 150 is rotated counterclockwise. While the sheet P is conveyed by the drying belt 150 through the drying conveyance path 155, the ink image formed on the sheet P is dried.

  The upper conveyance path 200 is connected to the downstream side of the drying conveyance path 155 in the sheet conveyance direction, and conveys the sheet P upward. In the upper conveyance path 200, a fifth conveyance roller pair 201, a sixth conveyance roller pair 202, and a seventh conveyance roller pair 203 are disposed.

  The horizontal conveyance path 400 is connected to the downstream side of the upper conveyance path 200 in the sheet conveyance direction, and conveys the sheet P substantially horizontally and toward the right. The horizontal conveyance path 400 includes a ninth conveyance roller pair 401, a tenth conveyance roller pair 402, an eleventh conveyance roller pair 403, a twelfth conveyance roller pair 404, and a thirteenth conveyance roller pair 405. Is done.

  The discharge conveyance path 450 is connected to the downstream side of the horizontal conveyance path 400 in the sheet conveyance direction, and conveys the sheet P to the discharge tray 480. In the discharge conveyance path 450, a fourteenth conveyance roller pair 451 and a discharge roller pair 452 are disposed.

  The reverse conveyance path 302 is a sheet conveyance path branched downward from a branch point 300 disposed on the downstream side of the upper conveyance path 200. An eighth conveyance roller pair 301 is disposed in the reverse conveyance path 302. The reverse conveyance path 302 is used when the ink head unit 20 forms an image on the back surface of the sheet P after the image is formed on the front surface of the sheet P. At this time, the conveyance direction of the sheet P is reversed by rotating the eighth conveyance roller pair 301 from the normal rotation to the reverse rotation while the sheet P enters the reversal conveyance path 302.

  The return conveyance path 303 is a sheet conveyance path in which the reverse conveyance path 302 and the horizontal conveyance path 400 are connected, and the sheet P conveyed to the reverse conveyance path 302 and reversed in the conveyance direction is transferred to the horizontal conveyance path 400. To guide.

  The third transport path 460 is disposed from the double-sided branch point 406 disposed on the downstream side of the horizontal transport path 400 to the registration roller unit 50 of the merging transport unit 500. A fifth transport roller pair 461 is disposed on the third transport path 460. The third transport path 460 is used when the ink head unit 20 forms an image on the back surface of the sheet P after the image is formed on the front surface of the sheet P. The sheet P conveyed through the third conveyance path 460 by the fifth conveyance roller pair 461 is guided to the merging conveyance unit 500 and then conveyed toward the ink head unit 20 again.

  Next, with reference to FIG. 2 and FIG. 3, the merging and conveying unit 500 (sheet conveying device) will be described in detail. 2 and 3 are enlarged cross-sectional views of the merging and conveying unit 500. FIG. The merging and conveying unit 500 has a function of merging a plurality of sheet conveying paths and correcting the skew of the sheet P. In the merging / conveying unit 500, the first conveying path 121, the second conveying path 131, and the third conveying path 460 are merged. The second transport path 131 is disposed between the first transport path 121 and the third transport path 460 in a cross section including a direction intersecting with the roller axis of each transport roller (cross section including the sheet transport direction). A registration roller unit 50 is disposed on the downstream side in the sheet conveyance direction of the merging conveyance unit 500.

  The registration roller unit 50 includes a first opposing roller 51, a registration roller 52, a second opposing roller 53, and a motor 521.

  The first counter roller 51 is disposed in a lower part of the registration roller unit 50. The 1st opposing roller 51 is a roller member provided with the layer which consists of elastic materials around the metal shaft. In the present embodiment, a rubber material is used as the elastic material. The first opposing roller 51 forms a first nip portion N1 (FIG. 3) with the registration roller 52. The first counter roller 51 conveys the sheet P conveyed from the first conveyance path 121 and the second conveyance path 131 to the downstream side in the sheet conveyance direction.

  The registration roller 52 is disposed at a central portion of the registration roller unit 50 in the vertical direction. The registration roller 52 is a metal roller, and the surface of the registration roller 52 has high slidability. The registration roller 52 may be formed of a member having a hard surface and high slidability, such as a resin material such as iron, aluminum, or POM. The surface of the registration roller 52 has higher hardness and higher slidability than the surfaces of the first opposing roller 51 and the second opposing roller 53. The evaluation of slidability is based on JIS-K7125 (Plastic-Film and Sheet Friction Coefficient Test Method) and the friction coefficient (static friction coefficient and dynamic friction coefficient) is used as an index. That is, the surface of the registration roller 52 is set to have a lower friction coefficient than the surfaces of the first opposed roller 51 and the second opposed roller 53. Moreover, evaluation of hardness is based on JIS-K6253. The registration roller 52 forms a first nip portion N1 with the first counter roller 51, and forms a second nip portion N2 (FIG. 3) with the second counter roller 53. The first nip portion N1 is disposed on the downstream side of the first conveyance path 121 and the second conveyance path 131 in the sheet conveyance direction. The second nip portion N2 is disposed on the downstream side of the third conveyance path 460 in the sheet conveyance direction. The registration roller 52 conveys the sheet P conveyed from the first conveyance path 121, the second conveyance path 131, and the third conveyance path 460 to the downstream side in the sheet conveyance direction. The registration roller 52 is rotationally driven by a motor 521 (drive unit). At this time, the registration roller 52 is rotatable around the roller axis in a first direction and a second direction (clockwise and counterclockwise) opposite to the first direction.

  The second opposing roller 53 is disposed in the upper part of the registration roller unit 50. The second opposing roller 53 is a roller member that includes a layer made of an elastic material around a metal shaft. In the present embodiment, a rubber material is used as the elastic material. The second opposing roller 53 forms a second nip portion N2 (FIG. 3) with the registration roller 52. The second counter roller 53 transports the sheet P transported from the third transport path 460 downstream in the sheet transport direction.

  The first counter roller 51 and the second counter roller 53 are driven to rotate following the registration roller 52. That is, when the registration roller 52 is rotationally driven by the driving means, the first opposing roller 51 and the second opposing roller 53 are rotationally driven by the frictional force in the first nip portion N1 and the second nip portion N2, respectively. The The first counter roller 51 and the second counter roller 53 are rotatable in forward and reverse directions according to the rotation direction of the registration roller 52. The transmission of the rotational driving force from the registration roller 52 to the first opposing roller 51 and the second opposing roller 53 may be by a drive transmission mechanism including a gear (not shown).

  A downstream portion of the first conveyance path 121 in the sheet conveyance direction is disposed in a lower portion of the merging conveyance unit 500. Between the second conveyance roller pair 125 and the third conveyance roller pair 126 of the first conveyance path 121, a first conveyance wall 61, a second conveyance wall 62, a third conveyance wall 63, and a fourth conveyance wall 64 are provided. Each is arranged. The first transport wall 61 and the second transport wall 62 are disposed between the second transport roller pair 125 and the third transport roller pair 126 and are opposed to each other at a position on the second transport roller pair 125 side. . The third transport wall 63 and the fourth transport wall 64 are disposed between the second transport roller pair 125 and the third transport roller pair 126 and are opposed to each other at a position on the third transport roller pair 126 side. . The first conveyance wall 61, the second conveyance wall 62, the third conveyance wall 63, and the fourth conveyance wall 64, so that the second conveyance roller pair 125 and the third conveyance roller pair 126 are between the first conveyance path 121. Defined.

  Further, the first opposing wall 70 and the first introduction wall 75 are disposed between the third conveyance roller pair 126 and the registration roller unit 50 in the first conveyance path 121. A part of the first conveyance path 121 is formed by arranging the first facing wall 70 and the first introduction wall 75 to face each other.

  The first opposing wall 70 is upstream of the first nip portion N1 in the sheet conveying direction, and contacts the first opposing roller 51 among the sheets P (first sheets) conveyed through the first conveying path 121. It arrange | positions so as to oppose the sheet surface (1st sheet surface) to be performed. In other words, the first facing wall 70 is between the third conveyance roller pair 126 and the registration roller unit 50 and forms the lower surface portion of the first conveyance path 121. The first facing wall 70 includes a first upstream wall 71 and a first downstream wall 72. The first upstream wall 71 is a wall portion of the third transport roller pair 126 that extends from the third B transport roller 126B to the downstream side in the sheet transport direction. The first upstream wall 71 is arranged to incline in the left direction as it goes upward. The first downstream wall 72 is a wall portion disposed on the registration roller unit 50 side, and is connected to the downstream side of the first upstream wall 71 in the sheet conveyance direction. The first downstream wall 72 is disposed so as to be inclined further leftward than the first downstream wall 72. A first bent portion 73 is disposed at a portion where the first upstream wall 71 and the first downstream wall 72 are connected. The first bent portion 73 is arranged to be bent toward the first transport path 121.

  The first introduction wall 75 is on the upstream side of the first nip portion N1 in the sheet conveyance direction, and comes into contact with the registration roller 52 among the sheets P (first sheets) conveyed on the first conveyance path 121. It arrange | positions so that a sheet surface (2nd sheet surface) may be opposed. In other words, the first introduction wall 75 forms the upper surface portion of the first conveyance path 121 between the third conveyance roller pair 126 and the registration roller unit 50. The first introduction wall 75 is a wall portion of the third transport roller pair 126 that extends from the third A transport roller pair 126A to the downstream side in the sheet transport direction. The first introduction wall 75 is disposed so as to cover the first upstream wall 71 and the first downstream wall 72. As shown in FIG. 3, the first introduction wall 75 is opposed to the first upstream wall 71 and has a first inclined surface 751 inclined to the left with an inclination angle substantially equal to that of the first upstream wall 71; A first curved surface 752 (first curved portion) that is connected to the first inclined surface and curves upward, and is connected to the first curved surface 752 and extends toward the registration roller portion 50. A first horizontal plane 753. The first curved surface 752 is curved with respect to the first conveyance path 121 so as to have a concave shape. Of the first introduction wall 75, a first separation point 75A is disposed at an end portion on the registration roller unit 50 side.

  A downstream portion of the second conveyance path 131 in the sheet conveyance direction is disposed at a central portion in the vertical direction of the merging conveyance unit 500. A third facing wall 81 and a third introduction wall 82 are disposed between the fourth transport roller pair 134 and the registration roller unit 50 in the second transport path 131. A part of the second conveyance path 131 is formed by arranging the third facing wall 81 and the third introduction wall 82 to face each other.

  The third opposing wall 81 is between the fourth transport roller pair 134 and the registration roller unit 50 and forms a lower surface portion of the second transport path 131. The third opposing wall 81 is on the upstream side of the first nip portion N1 in the sheet conveying direction and contacts the first opposing roller 51 among the sheets P (third sheet) conveyed on the second conveying path 131. It arrange | positions so as to oppose the sheet surface (3rd sheet surface) to be performed. The 3rd opposing wall 81 is a wall part arrange | positioned in a substantially horizontal direction.

  The third introduction wall 82 (second curved portion) is between the fourth conveyance roller pair 134 and the registration roller unit 50 and forms an upper surface portion of the second conveyance path 131. The third introduction wall 82 is on the upstream side of the first nip portion N1 in the sheet conveyance direction, and comes into contact with the registration roller 52 among the sheets P (third sheets) conveyed through the second conveyance path 131. It arrange | positions so that a sheet surface (4th sheet surface) may be opposed. The third introduction wall 82 is disposed so as to cover the upper side of the third opposing wall 81. The third introduction wall 82 includes a curved surface that curves upward. In other words, the third introduction wall 82 includes a concave curved surface with respect to the second conveyance path 131.

  A downstream portion of the third conveyance path 460 in the sheet conveyance direction is disposed in an upper portion of the merging conveyance unit 500. Between the sixth conveyance roller pair 462 and the registration roller unit 50 in the third conveyance path 460, the second opposing wall 90 and the second introduction wall 95 are disposed. A part of the third conveyance path 460 is formed by arranging the second facing wall 90 and the second introduction wall 95 to face each other.

  The second opposing wall 90 is on the upstream side of the second nip portion N2 in the sheet conveying direction, and is on the sheet surface in contact with the second opposing roller 53 among the sheets P conveyed on the third conveying path 460. It arrange | positions so that it may oppose. In other words, the second facing wall 90 forms the upper surface portion of the third transport path 460 between the sixth transport roller pair 462 and the registration roller unit 50. The second opposing wall 90 includes a second upstream wall 91 and a second downstream wall 92. The second upstream wall 91 is a wall portion of the sixth conveying roller pair 462 that extends from the sixth A conveying roller 462A to the downstream side in the sheet conveying direction. The second upstream wall 91 is arranged to incline in the left direction as it goes downward. The second downstream wall 92 is a wall portion disposed on the registration roller unit 50 side, and is connected to the downstream side of the second upstream wall 91 in the sheet conveying direction. The second downstream wall 92 is disposed so as to be inclined further leftward than the second upstream wall 91. A second bent portion 93 is disposed at a portion where the second upstream wall 91 and the second downstream wall 92 are connected. The second bent portion 93 is disposed so as to be bent toward the third conveyance path 460.

  The second introduction wall 95 is upstream of the second nip portion N2 in the sheet conveyance direction, and faces the sheet surface that contacts the registration roller 52 among the sheets P conveyed through the third conveyance path 460. It is arranged as follows. In other words, the second introduction wall 95 forms the lower surface portion of the third conveyance path 460 between the sixth conveyance roller pair 462 and the registration roller unit 50. The second introduction wall 95 is a wall portion that extends from the sixth conveyance roller 462 </ b> B to the downstream side in the sheet conveyance direction in the sixth conveyance roller pair 462. The second introduction wall 95 is disposed so as to be covered with the second upstream wall 91 and the second downstream wall 92. The second introduction wall 95 faces the second upstream wall 91 and has a second inclined surface 951 inclined leftward with an inclination angle substantially equal to that of the second upstream wall 91, and the second inclined surface 951. The second curved surface 952 is connected and curved downward, and the third inclined surface 953 is connected to the second curved surface 952 and extends toward the registration roller unit 50. Of the second introduction wall 95, a second separation point 95 </ b> A is disposed at an end portion on the registration roller unit 50 side.

  As described above, in the present embodiment, the three sheet conveyance paths are merged in the merge conveyance unit 500. In the registration roller unit 50, only three rollers, that is, a first opposing roller 51, a registration roller 52, and a second opposing roller 53 are arranged. On the other hand, when a pair of registration rollers is arranged in each sheet conveyance path, a total of six rollers are required. As described above, the sheet conveyance paths of the image forming apparatus 1 are compactly arranged by joining the plurality of sheet conveyance paths and reducing the number of rollers used for the registration function. A guide member 140 </ b> A is disposed downstream of the registration roller unit 50 in the sheet conveyance direction. The guide member 140 </ b> A has a guide surface that is continuous with the belt surface of the conveyor belt 140. The guide member 140A has a function of guiding the sheet P that has passed through the first nip portion N1 and the second nip portion N2 to the conveyance belt 140.

  Next, with reference to FIG. 3, the structure of the confluence | merging conveyance part 500 is further explained in full detail. In the present embodiment, the registration roller unit even when the sheet P conveyed from the three sheet conveyance paths of the first conveyance path 121, the second conveyance path 131, and the third conveyance path 460 is skewed. At 50, the skew is preferably corrected. For this reason, the present embodiment is characterized by the arrangement of the wall portions constituting the sheet conveyance paths and the registration roller portions 50.

  In FIG. 3, a straight line passing through the first bent portion 73 of the first opposing wall 70 and passing through the first separation point 75A of the first introduction wall 75 is defined as a first straight line L1. In other words, the first straight line L1 is in point contact (contact with) the tip of the first introduction wall 75 when the straight line passing through the first bent portion 73 is rotated in the cross-sectional view of FIG. It corresponds to a thing. The first separation point 75A corresponds to the point contact point (contact point). A point where the first straight line L1 intersects the peripheral surface of the registration roller 52 is defined as a first outer peripheral portion S. The first outer peripheral portion S is located on the peripheral surface of the registration roller 52 upstream of the first nip portion N1 in the sheet transport direction in the sheet transport direction of the sheet P transported through the first transport path 121. Further, the tangent line of the registration roller 52 in the first outer peripheral portion S is defined as the second straight line L2. In the present embodiment, the angle α formed by the first straight line L1 and the second straight line L2 is set to be 60 degrees or less.

  In FIG. 3, a straight line passing through the second bent portion 93 of the second opposing wall 90 and passing through the second separation point 95A of the second introduction wall 95 is defined as a third straight line L3. In other words, the third straight line L3 corresponds to the straight line that is in point contact with the tip of the second introduction wall 95 when the straight line passing through the second bent portion 93 is rotated in the cross-sectional view of FIG. . The second leaving point 95A corresponds to the point contact point. A point where the third straight line L3 intersects the peripheral surface of the registration roller 52 is defined as a second outer peripheral portion T. The second outer peripheral portion T is located on the peripheral surface of the registration roller 52 upstream of the second nip portion N2 in the sheet transport direction in the sheet transport direction of the sheet P transported through the third transport path 460. Further, a tangent line of the registration roller 52 in the second outer peripheral portion T is defined as a fourth straight line L4. In the present embodiment, the angle β formed by the third straight line L3 and the fourth straight line L4 is set to be 60 degrees or less.

  Next, the state of the sheet P conveyed through the merging conveyance unit 500 will be described in detail with reference to FIGS. 4 to 6 are diagrams illustrating a state in which the sheet P1 (first sheet) conveyed from the first conveyance path 121 is conveyed through the merging conveyance unit 500. FIG. 7 to 9 are diagrams illustrating a state in which the sheet P2 (third sheet) conveyed from the second conveyance path 131 is conveyed through the merging conveyance unit 500. Further, FIGS. 10 to 12 are views showing a state where the sheet P3 (second sheet) conveyed from the third conveyance path 460 is conveyed through the merging conveyance unit 500. FIG.

  With reference to FIGS. 1, 2, and 4, the state of the sheet P <b> 1 conveyed through the first conveyance path 121 will be described. Along with the image forming operation, the first pickup roller 122 sends the sheet P <b> 1 of the cassette 120 to the first conveyance path 121. Thereafter, the sheet P1 conveyed by the first sheet feeding roller pair 123, the first conveying roller pair 124, and the second conveying roller pair 125 rotated by a driving unit (not shown) is transferred by the third conveying roller pair 126 in FIG. Further, it is transported along the first transport path 121. The leading end of the sheet P1 that has entered the first A conveyance path 121A, which is the downstream side of the first conveyance path 121, further contacts the first horizontal surface 753 from the first curved surface 752 of the first introduction wall 75, and further downstream. It is conveyed to.

  Eventually, when the leading end of the sheet P1 reaches the first separation point 75A, the surface of the sheet P1 that faces the first facing wall 70 is in contact with the first bent portion 73. Then, the leading end portion of the sheet P1 that has come out from the first separation point 75A to the downstream side in the sheet conveying direction comes into contact with the first contact portion S1 on the peripheral surface of the registration roller 52 in a state where the rotation is stopped. At this time, in the sheet P1, the first sheet downstream portion P11 located between the first downstream wall 72 and the first horizontal plane 753 and the first curved surface 752 includes the first separation point 75A and the first bent portion. 73 and is slightly curved toward the first curved surface 752 side. For this reason, the first contact portion S1 is located at substantially the same position as the first outer peripheral portion S described above, or is located closer to the first nip portion N1 than the first outer peripheral portion S. That is, the angle formed between the tangent line of the registration roller 52 and the leading end portion of the sheet P1 in the first contact portion S1 is equal to or less than the aforementioned angle α.

  The registration roller 52 is made of a metal material, and the slidability of the surface of the registration roller 52 is set high. For this reason, the leading end portion of the sheet P1 that is in contact with the first contact portion S1 enters the first nip portion N1 while sliding on the peripheral surface of the registration roller 52. At this time, even when the sheet P1 is skewed and the leading edge of the sheet P1 is inclined, the rotation of the registration roller 52 is stopped, so that the leading edge of the sheet P1 is the first nip portion. N1 is aligned in a direction orthogonal to the sheet conveying direction.

  The third conveyance roller pair 126 further conveys the sheet P1 with the leading end of the sheet P1 abutting against the first nip portion N1. For this reason, the 1st sheet | seat downstream part P11 of the sheet | seat P1 further curves to the 1st curved surface 752 side (FIG. 5). In the present embodiment, since the first curved surface 752 is formed on the first introduction wall 75 downstream of the first bent portion 73 in the sheet conveying direction, the sheet P1 is suitably curved (forms a loop). It becomes possible. Therefore, even if the leading end portion of the sheet P1 is in contact with the first nip portion N1, the sheet P1 is not wrinkled or the sheet P1 is not buckled.

  Then, after the leading end of the sheet P1 enters the first nip portion N1, the registration roller 52 is rotationally driven in the direction of arrow D12 as shown in FIG. 6 in accordance with the timing of image formation. At the same time, the first counter roller 51 is driven to rotate in the direction of the arrow D11 following the registration roller 52. As a result, the sheet P <b> 1 abuts on the guide member 140 </ b> A disposed upstream of the transport belt 140 and is then transported toward the ink head unit 20 by the transport belt 140.

  As described above, in the present embodiment, the sheet P1 can go to the ink head unit 20 in a state where the skew of the sheet P1 conveyed through the first conveyance path 121 is preferably corrected. In particular, a first straight line L1 passing through the first bent portion 73 of the first opposing wall 70 and the first separation point 75A of the first introduction wall 75 is disposed so as to intersect the peripheral surface of the registration roller 52. Yes. Therefore, the leading end portion of the sheet P <b> 1 conveyed through the first conveyance path 121 abuts not on the first opposing roller 51 but on the peripheral surface of the registration roller 52. For this reason, the leading end portion of the sheet P1 smoothly enters the first nip portion N1 due to the slidability of the peripheral surface of the registration roller 52 made of a metal material. In other words, the front end portion of the sheet P1 does not enter the first nip portion N1 when the front end portion of the sheet P1 comes into contact with the peripheral surface of the first counter roller 51 whose surface is made of a rubber material.

  Further, as described above, since the angle α formed by the first straight line L1 and the second straight line L2 is set to 60 degrees or less, when the leading end portion of the sheet P1 comes into contact with the peripheral surface of the registration roller 52, The impact of can be suppressed. For this reason, when the sheet P1 comes into contact with the peripheral surface of the registration roller 52, wrinkles are not generated at the front end portion of the sheet P1.

  Further, when the angle α is set in the above range, the portion of the sheet P1 sandwiched between the first opposing wall 70 and the first introduction wall 75 when the leading end of the sheet P1 enters the first nip portion N1. Already has a slight deflection. And the 1st curved surface 752 is previously formed in the 1st introductory wall 75 so that a loop may be formed in the sheet | seat P1 by the slight bending of this sheet | seat P1 growing. Therefore, even in the merging and conveying unit 500 arranged in a compact manner, it is possible to suitably form a loop on the sheet P1.

  Next, with reference to FIG. 1 and FIG. 7, the state of the sheet P2 conveyed in the second conveyance path 131 will be described. Along with the image forming operation, the second pickup roller 132 sends out the sheet P <b> 2 of the manual feed tray 130 to the second conveyance path 131. The sheet P2 is brought into contact with the second pickup roller 132 by a manual lift plate 130A disposed in the manual feed tray 130. Further, the sheet P2 sent out by the second pickup roller 132 is guided by a guide plate 130B disposed between the manual feed lift plate 130A and the second pickup roller 132, and on the circumferential surface of the second A feeding roller 133A. After the contact, the second paper feed roller pair 133 enters the nip portion.

  Thereafter, the sheet P <b> 2 is further conveyed on the second conveyance path 131 by the second paper feed roller pair 133 and the fourth conveyance roller pair 134 that are rotated by a driving unit (not shown).

  Then, the leading end portion of the sheet P2 that has advanced along the third opposing wall 81 comes into contact with the third contact portion U1 that is the peripheral surface of the registration roller 52 in a state where the rotation is stopped. In the present embodiment, the third opposing wall 81 is disposed at a position higher than the first nip portion N1 in the vertical direction. Further, an angle formed by a straight line extending from the third facing wall 81 and a tangent line of the registration roller 52 at the third contact portion U1 is set to be 50 degrees or less.

  As described above, the registration roller 52 is made of a metal material, and the slidability of the surface of the registration roller 52 is set high. For this reason, the leading end portion of the sheet P2 that is in contact with the third contact portion U1 at the above angle enters the first nip portion N1 while sliding on the peripheral surface of the registration roller 52. At this time, even when the sheet P2 is skewed and the leading edge of the sheet P2 is inclined, the rotation of the registration roller 52 is stopped, so that the leading edge of the sheet P2 is the first nip portion. N1 is aligned in a direction orthogonal to the sheet conveying direction.

  The fourth conveyance roller pair 134 further conveys the sheet P2 with the leading end of the sheet P2 abutting against the first nip portion N1. For this reason, the 2nd sheet | seat downstream part P21 of the sheet | seat P2 curves to the 3rd introductory wall 82 side (FIG. 8). Thus, in this embodiment, the 3rd opposing wall 81 is extended in the substantially horizontal direction, and the 3rd introductory wall 82 facing the 3rd opposing wall 81 is formed from a curved surface. Therefore, the sheet P2 in a state where the leading end is stopped at the first nip portion N1 can be appropriately curved (form a loop). As a result, even if the leading end portion of the sheet P2 is in contact with the first nip portion N1 and stopped, the sheet P2 is not wrinkled or the sheet P2 is not buckled.

  Then, after the leading end portion of the sheet P2 enters the first nip portion N1, the registration roller 52 is rotationally driven in the direction of the arrow D22 as shown in FIG. 9 in accordance with the timing of image formation. At the same time, the first facing roller 51 is driven to rotate in the direction of the arrow D21 following the registration roller 52. As a result, the sheet P <b> 2 contacts the guide member 140 </ b> A disposed upstream of the transport belt 140 and is then transported toward the ink head unit 20 by the transport belt 140.

  As described above, in the present embodiment, the sheet P2 can go to the ink head unit 20 in a state where the skew of the sheet P2 conveyed through the second conveyance path 131 is preferably corrected. In particular, a straight line obtained by extending the third opposing wall 81 made of a plane is disposed so as to intersect the peripheral surface of the registration roller 52. Therefore, the leading end portion of the sheet P <b> 2 conveyed through the second conveyance path 131 is in contact with the peripheral surface of the registration roller 52 instead of the first counter roller 51. For this reason, the leading end portion of the sheet P2 smoothly enters the first nip portion N1 due to the slidability of the peripheral surface of the registration roller 52 made of a metal material. In other words, the front end portion of the sheet P2 does not enter the first nip portion N1 when the front end portion of the sheet P2 comes into contact with the peripheral surface of the first counter roller 51 whose surface is made of a rubber material.

  Furthermore, as described above, the angle formed by the sheet P2 (a straight line extending the third opposing wall 81) that contacts the third contact portion U1 and the tangential direction of the registration roller 52 at the third contact portion U1 is as follows. It is set to be 50 degrees or less. For this reason, the impact when the leading end of the sheet P2 comes into contact with the peripheral surface of the registration roller 52 is suppressed. For this reason, when the sheet P2 comes into contact with the peripheral surface of the registration roller 52, wrinkles are not generated at the front end portion of the sheet P2.

  Further, the angle at which the sheet P2 contacts the peripheral surface of the registration roller 52 is set in the above range, so that when the leading end of the sheet P2 enters the first nip portion N1, the third facing of the sheet P2 is performed. Slight bending has already occurred in the portion sandwiched between the wall 81 and the third introduction wall 82. A curved surface is formed on the third introduction wall 82 in advance so that a loop is formed on the sheet P2 by growing a slight deflection of the sheet P2. Therefore, even in the merging and conveying unit 500 arranged in a compact manner, it is possible to suitably form a loop on the sheet P2.

  Next, with reference to FIG. 1 and FIG. 10, the state of the sheet P3 conveyed on the third conveyance path 460 will be described. The sheet P3 on which image formation has been performed on the surface by the ink head unit 20 is conveyed through the drying conveyance path 155, the upper conveyance path 200, the reverse conveyance path 302, the return conveyance path 303, and the horizontal conveyance path 400, and then a double-side branch point. It is conveyed from 406 to the third conveyance path 460. Thereafter, the sheet P3 conveyed by the fifth conveyance roller pair 461 rotated by a driving unit (not shown) is further conveyed on the third conveyance path 460 by the sixth conveyance roller pair 462 in FIG. The leading end portion of the sheet P3 that has entered the 3A conveyance path 460A, which is the downstream portion of the third conveyance path 460, further contacts the third inclined surface 953 from the second curved surface 952 of the second introduction wall 95. It is conveyed downstream.

  Eventually, when the leading end of the sheet P3 reaches the second separation point 95A, the surface of the sheet P3 facing the second facing wall 90 is in contact with the second bent portion 93. Then, the leading end portion of the sheet P3 that has come out from the second separation point 95A to the downstream side in the sheet conveyance direction comes into contact with the second contact portion T1 on the peripheral surface of the registration roller 52 in a state where the rotation is stopped. At this time, in the seat P3, the third seat downstream portion P31 located between the second downstream wall 92 and the second curved surface 952 and the third inclined surface 953 has the second separation point 95A and the second bent point. It arrange | positions between the parts 93, and is curving slightly toward the 2nd curved surface 952 side. For this reason, the second contact portion T1 is located at substantially the same position as the second outer peripheral portion T described above, or is located closer to the second nip portion N2 than the second outer peripheral portion T. That is, the angle formed by the tangent line of the registration roller 52 at the second contact portion T1 and the leading end portion of the sheet P3 is equal to or less than the aforementioned angle β.

  As described above, the registration roller 52 is made of a metal material, and the slidability of the surface of the registration roller 52 is set high. For this reason, the leading end portion of the sheet P3 in contact with the second contact portion T1 enters the second nip portion N2 while sliding on the peripheral surface of the registration roller 52. At this time, even when the sheet P3 is skewed and the leading edge of the sheet P3 is tilted, the rotation of the registration roller 52 is stopped, so that the leading edge of the sheet P3 is the second nip portion. N2 is aligned in a direction orthogonal to the sheet conveying direction.

  The sixth transport roller pair 462 further transports the sheet P3 with the leading end of the sheet P3 abutting against the second nip portion N2. For this reason, the 3rd sheet | seat downstream part P31 of the sheet | seat P3 further curves to the 2nd curved surface 952 side (FIG. 11). In the present embodiment, since the second curved surface 952 is formed on the second introduction wall 95 downstream of the second bent portion 93 in the sheet conveyance direction, the sheet P3 is suitably curved (forms a loop). It becomes possible. Therefore, even if the leading end portion of the sheet P3 is in contact with the second nip portion N2 and stopped, the sheet P3 is not wrinkled or the sheet P3 is not buckled.

  Then, after the leading end of the sheet P3 enters the second nip portion N2, the registration roller 52 is rotationally driven in the direction of arrow D32 as shown in FIG. At the same time, the second opposing roller 53 is driven to rotate in the direction of arrow D33 following the registration roller 52. Note that the rotation direction (arrow D32) of the registration roller 52 when the sheet P3 is conveyed is opposite to the rotation direction (arrows D12 and D22) of the registration roller 52 when the sheets P1 and P2 are conveyed. In the present embodiment, the second counter roller 53 is disposed so that the axis of the second counter roller 53 is shifted to the left from the axis of the registration roller 52 (arrow D4). In other words, the tangent line of the registration roller 52 at the second nip portion N2 intersects the guide surface of the guide member 140A. As a result, the leading end P32 of the sheet P3 comes into contact with the guide surface of the guide member 140A disposed upstream of the conveying belt 140 with an acute angle γ.

  An image is formed on the surface of the sheet P3 in the ink head unit 20. For this reason, the sheet P3 conveyed through the merging conveyance unit 500 tends to be in an upper curl state having a concave shape in the upward direction. Furthermore, when the conveyance belt 140 carries the sheet P (P3) by the air suction force, a paper jam is likely to occur if the leading end of the sheet P3 is lifted by the upper curl. Even in such a case, as described above, the sheet P3 (P32) is brought into contact with the guide member 140A at an angle γ, so that the upper curl is preferably corrected.

  As described above, in the present embodiment, the sheet P3 can go to the ink head unit 20 in a state where the skew of the sheet P3 conveyed through the third conveyance path 460 is preferably corrected. In particular, a third straight line L3 passing through the second bent portion 93 of the second opposing wall 90 and the second separation point 95A of the second introduction wall 95 is disposed so as to intersect the peripheral surface of the registration roller 52. Yes. Accordingly, the leading end portion of the sheet P <b> 3 conveyed through the third conveyance path 460 contacts the peripheral surface of the registration roller 52 instead of the second counter roller 53. For this reason, the leading end portion of the sheet P3 smoothly enters the second nip portion N2 due to the slidability of the peripheral surface of the registration roller 52 made of a metal material. In other words, the front end portion of the sheet P3 does not buckle when the front end portion of the sheet P3 comes into contact with the peripheral surface of the second facing roller 53 whose surface is made of a rubber material. In addition, the leading edge of the sheet P3 is not prevented from entering the second nip portion N2.

  Further, as described above, since the angle β formed by the third straight line L3 and the fourth straight line L4 is set to 60 degrees or less, when the leading end of the sheet P3 comes into contact with the peripheral surface of the registration roller 52, The impact of can be suppressed. For this reason, when the sheet P3 comes into contact with the peripheral surface of the registration roller 52, wrinkles are not generated at the front end portion of the sheet P3.

  Further, by setting the angle β in the above range, the sheet P3 is sandwiched between the second downstream wall 92 and the second curved surface 952 when the leading end of the sheet P3 enters the second nip portion N2. The part already has a slight deflection. And the 2nd curved surface 952 is previously formed in the 2nd introducing | transducing wall 95 so that a loop may be formed in the sheet | seat P3 when the slight bending of this sheet | seat P3 grows large. Therefore, it is possible to form a loop suitably on the sheet P3 even in the merging and conveying unit 500 arranged in a compact manner.

  Furthermore, in the present embodiment, the second counter roller 53 is arranged so that the axis of the second counter roller 53 is shifted to the left from the axis of the registration roller 52 (arrow D4). Therefore, even when the sheet P3 is curled because an image is formed on the surface, the sheet P3 discharged from the second nip portion N2 enters the guide member 140A at an acute angle. Thus, the curl is preferably eliminated.

  The sheet conveying apparatus according to the embodiment of the present invention and the image forming apparatus including the sheet conveying apparatus have been described above. However, the present invention is not limited to this, and for example, the following modified embodiment can be taken. .

  (1) In the above embodiment, the three sheet conveyance paths of the first conveyance path 121, the second conveyance path 131, and the third conveyance path 460 have been described in the aspect of being merged by the merging conveyance unit 500. The configuration of the sheet conveyance path is not limited to this. The sheet conveyance path to be merged may have two configurations of the first conveyance path 121 and the third conveyance path 460. Moreover, the structure by which four or more sheet conveyance paths merge may be sufficient.

  (2) A sheet conveying path that joins the merging and conveying unit 500 from below, a sheet conveying path that joins the merging and conveying unit 500 substantially horizontally at the center in the vertical direction, and a sheet conveyance that joins the merging and conveying unit 500 from above As the path, the cassette 120, the manual feed tray 130, and the conveyance path starting from the conveyance path for double-sided printing have been described, but the present invention is not limited to this. Depending on the layout of the image forming apparatus 1, the sheet conveyance path may be arranged at a different position.

1 Image forming apparatus 10 Main body housing (housing)
120 cassette 120 (sheet cassette)
121 First transport path (first sheet transport path)
121A 1A conveyance path 122 1st pickup roller 123 1st paper feed roller pair 124 1st conveyance roller pair 125 2nd conveyance roller pair 126 3rd conveyance roller pair 130 Manual feed tray 130A Manual feed 131 131 2nd conveyance path (3rd sheet) Transport path)
132 Second pickup roller 133 Second paper feed roller pair 134 Fourth transport roller pair 20 Ink head unit 140 Transport belt 145 Image forming transport path 150 Drying belt 155 Drying transport path 200 Upper transport path 300 Branch point 301 Eight transport roller pair 302 Reverse conveyance path 303 Return conveyance path 400 Horizontal conveyance path 450 Discharge conveyance path 460 Third conveyance path (second sheet conveyance path)
460A 3A conveyance path 461 5th conveyance roller pair 462 6th conveyance roller pair 480 Discharge tray 500 Conveyance introduction part 51 1st counter roller (1st roller)
52 Registration roller (second roller)
521 Motor (drive unit)
53 Second opposing roller (third roller)
70 First opposing wall (first transfer wall)
71 First upstream wall (first wall surface)
72 1st downstream wall (2nd wall surface)
73 1st bending part (bending top part)
75 First introduction wall (second transfer wall)
75A First separation point 75B First introduction wall downstream portion 751 First inclined surface 752 First curved surface (first curved portion)
753 1st horizontal plane S 1st outer peripheral part S1 1st contact part N1 1st nip part 81 3rd opposing wall (3rd conveyance wall)
82 Third introduction wall (fourth transfer wall)
U1 3rd contact part 90 2nd opposing wall 91 2nd upstream wall 92 2nd downstream wall 93 2nd bending part 95 2nd introduction wall 95A 2nd separation point 95B 2nd introduction wall downstream part T 2nd outer peripheral part T1 1st 2 contact part N2 2nd nip part L1 1st straight line L2 2nd straight line L3 3rd straight line L4 4th straight line

Claims (14)

A housing,
A first sheet transport path disposed in the housing and transporting a first sheet;
A second sheet transport path disposed in the housing and transporting the second sheet;
A first registration roller pair that is disposed in the first sheet conveyance path and includes a first roller and a second roller that forms a first nip portion with the first roller;
A second registration roller pair that is disposed in the second sheet conveyance path and includes a second roller and a third roller that forms a second nip portion between the second roller and the second roller,
The surfaces of the first and third rollers are made of an elastic material,
The surface of the second roller is composed of a metal material or a resin material having a higher hardness and a lower coefficient of friction than the surfaces of the first and third rollers. The surfaces of the first and third rollers, the sheet conveying device according to claim 1, characterized in that that consists of a rubber material. A drive unit that rotates the second roller around a roller axis;
The drive unit is configured such that after the leading end portion of the first sheet or the second sheet comes into contact with the first nip portion or the second nip portion in a state where the rotation of the second roller is stopped, The sheet conveying apparatus according to claim 1, wherein the roller is driven to rotate. The drive unit rotates the second roller around the roller axis in a first direction and a second direction opposite to the first direction,
In the first state in which the first sheet passes through the first nip portion, the driving unit is in the first direction, and in the second state in which the second sheet passes through the second nip portion, The sheet conveying apparatus according to claim 3, wherein the second roller is rotationally driven in the second direction.   The sheet conveying apparatus according to claim 3 or 4, wherein the first and third rollers are rotated by following the second roller. The first sheet conveyance path is disposed upstream of the first nip portion in the sheet conveyance direction so as to face the first sheet surface that is in contact with the first roller of the first sheet. A first transfer wall;
The first sheet conveyance path is disposed on the upstream side of the first nip portion in the sheet conveyance direction so as to face the second sheet surface abutting on the second roller of the first sheet. A second transfer wall,
The first conveying wall is connected to the first wall surface so as to intersect with the first wall surface disposed on the upstream side in the sheet conveying direction and the first wall surface, and the first roller In a cross-sectional view including a second wall surface extending to the vicinity, a boundary between the first wall surface and the second wall surface and including a sheet conveyance direction of the first sheet, the first sheet conveyance path A bent top portion that protrudes toward the
The terminal portion of the second transport wall is disposed to face the peripheral surface of the second roller,
In the cross-sectional view, a first straight line passing through the bent top and contacting the terminal end of the second transport wall on the downstream side of the bent top in the sheet transport direction intersects the peripheral surface of the second roller. The sheet conveying apparatus according to claim 3, wherein the sheet conveying apparatus is a sheet conveying apparatus.   An angle formed by a tangent line of the second roller and the first straight line at a first outer peripheral point where the first straight line intersects a peripheral surface of the second roller is set to 60 degrees or less. The sheet conveying apparatus according to claim 6.   The said 2nd conveyance wall is provided with the 1st curved part which curved to the concave shape with respect to the said 1st sheet conveyance path facing the said 2nd wall surface. The sheet conveying apparatus according to the description.   In a cross-sectional view including the sheet conveyance direction of the first sheet, a third sheet conveyance that is disposed between the first sheet conveyance path and the second sheet conveyance path and conveys the third sheet to the first nip portion. The sheet conveying apparatus according to claim 1, further comprising a path. The third sheet conveying path is
Arranged upstream of the first nip portion of the third sheet conveyance path in the sheet conveyance direction and facing the third sheet surface that contacts the first roller of the third sheet. A third transfer wall;
Arranged to be upstream of the first nip portion of the third sheet conveyance path in the sheet conveyance direction and to face the fourth sheet surface that is in contact with the second roller of the third sheet. A fourth transfer wall,
The sheet conveying apparatus according to claim 9, wherein the third conveying wall is a flat surface extending toward a peripheral surface of the second roller.   An angle formed by a first extended straight line extending the third transport wall to the peripheral surface of the second roller, and a tangent line of the second roller at the intersection of the first extended straight line and the peripheral surface of the second roller. The sheet conveying apparatus according to claim 10, wherein is set to 50 degrees or less.   The sheet conveying apparatus according to claim 10, wherein the fourth conveying wall includes a second curved portion that is curved in a concave shape with respect to the third sheet conveying path. A sheet conveying device according to any one of claims 9 to 12,
A sheet cassette for storing the first sheet and supplying the sheet to the first sheet conveyance path;
A tray on which the third sheet is placed, and a sheet is supplied to the third sheet conveyance path;
An image forming unit that forms an image on the first sheet or the third sheet that has passed through the first nip portion;
After the front and back of the first sheet or the third sheet on which the image is formed in the image forming unit is reversed, the first sheet or the third sheet on which the front and back are reversed is used as the second sheet. The second sheet conveying path that conveys toward the image forming unit;
An image forming apparatus comprising: A guide member having a guide surface for guiding the second sheet that has passed through the second nip portion toward the image forming portion;
The image forming apparatus according to claim 13, wherein a tangent line of the second roller in the second nip portion intersects the guide surface of the guide member.

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