JP6138612B2 - Paper transport device, document feeder, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus including a pair of conveying guides that form a conveying path for conveying a sheet and a conveying roller provided in the conveying path, an original feeding apparatus including the sheet conveying apparatus, and the sheet conveying The present invention relates to an image forming apparatus such as a copying machine, a multifunction machine, and a facsimile machine provided with the apparatus.

  In a conventional paper transport device, a paper transport path is formed by a pair of transport guides. In this case, if the sheet is passed through the conveyance path formed only by the conveyance guide, the sheet is conveyed while rubbing the surface of the conveyance guide, so that static electricity is charged and the sheet is in close contact with the conveyance guide, making conveyance difficult. .

  Therefore, conventionally, a conveyance rib is provided on the opposed surfaces of the pair of conveyance guides, and the sheet is conveyed in the conveyance path while being in contact with the conveyance rib. In this case, in the state seen (viewed) from the paper width direction (direction perpendicular to the paper conveyance direction), the gap between the apexes of the opposite conveyance ribs is such that the paper is smoothly conveyed with a margin. Sufficient clearance is set. For example, with respect to a normal sheet thickness of about 0.1 mm, the gap between the apexes of the opposed conveying ribs is set to 2.5 to 3.0 mm when viewed from the sheet width direction.

  On the other hand, when the paper transported in the transport path undulates, the paper is in a seated state. When the sheet passes through the curved conveyance path in the conveyance path, the seated state becomes resistance, and noise such as a squeak noise (buzzing sound) is generated. In other words, if the paper that has been seated contacts the vicinity of the entrance of the curved conveyance path, the paper will be forcibly bent in the curving direction against the seated state, and the resistance at this time becomes noise such as squeak noise. Occur.

  In addition to the case where the paper is inevitably seated in the process of transporting the paper, there is a case where a seat is placed on the transport path and the seat is actively seated. There is a case where the body is in a sitting state for some reason such as skew. In some cases, the sheet itself is slightly wavy and is in a sitting state.

  For example, when the paper transporting device is mounted on the document feeding device, the document placed on the document tray is picked up by one pickup roller. Then, each sheet is separated one by one by two roller rollers (separation rollers) and conveyed to the conveyance path. At this time, since the conveyance speed by the roller roller is set slightly faster than the conveyance speed by the pickup roller, the document being picked up by the pickup roller is pulled by the roller roller, so that the document waved in the paper width direction. , May be in a sitting state.

  On the other hand, in the transport path for taking out the paper stored in the paper feed cassette one by one and forming an image in the image forming unit and discharging the paper to the paper discharge tray after fixing, the transport path just before discharging to the paper discharge tray A seating part is placed at the paper discharge port, which is the exit part, and by using this seating part, the output paper is seated to ensure that the paper can be discharged from the paper discharge port to the end. . In this case, in double-sided printing of the paper, the paper once discharged from the paper discharge port is not completely discharged, but is again drawn into the conveyance path and led to the reverse conveyance path. Therefore, when the drawn paper enters the curved conveyance path portion of the reverse conveyance path, noise such as a squeak noise may occur.

  Also, when picking up paper from the paper feed cassette, as in the case of the document feeder, the paper stored in the paper feed cassette is picked up by one pick-up roller and one by one by two roller rollers. When the sheet is transported to the transport path, the sheet may be in a seated state due to the difference in speed between the pickup roller and the suction roller.

  By the way, there are those described in Patent Documents 1 and 2 for reducing the noise generated during the conveyance of paper.

  The document conveying apparatus described in Patent Document 1 is an outer side conveyance that is a side on which a counter conveyance roller is provided among the document conveyance surfaces of two conveyance guide members that are opposed to the document front surface and the back surface of the first document conveyance path. An elastic sheet-like member is provided so as to protrude from the document conveying surface of the guide member into the document conveying space toward the document conveying surface of the inner conveying guide member. The elastic sheet-like member is provided so that the tip thereof is in contact with the document conveyance surface of the inner conveyance guide member and extends in the document width direction perpendicular to the document conveyance direction. Thereby, even if the document is released from the nipping by the transport roller or passes through a portion between the two transport guide members arranged in the document transport direction, a large displacement of the document can be suppressed. Therefore, it is possible to prevent collision of the upstream end of the document in the conveyance direction with the document conveyance surface of the conveyance guide member, and to suppress generation of noise due to the impact.

  Further, in the sheet conveying apparatus described in Patent Document 2, a pair of conveying roller pairs including a driving roller and a driven roller is used to form a sheet with a convex guide rib between the conveying roller pair upstream of these. Transport while pulling while rubbing. The guide surface when the effective conveyance width is between the outer end surface of the leftmost roller and the outermost surface of the rightmost roller among the driving rollers that are contacted when conveying the sheet having the minimum sheet passing width. The guide ribs are not provided in the area outside the effective conveyance width in FIG. As a result, the sheet conveying rubbing noise is generated between the upstream conveying roller pair and the downstream roller pair when the sheet is conveyed by the downstream conveying roller pair along the convex guide rib. It is possible to reduce.

JP 2010-150042 A JP 2008-280179 A

  However, in the document conveying device described in Patent Document 1, since a load is applied to the paper, there is a possibility that the rubbing sound between the paper and the elastic sheet-like member is generated in the case of the wavy paper, and the noise is not reduced. high. In addition, there is a problem that paper is jammed and meandering due to the load applied to the paper by the elastic sheet-like member.

  In the sheet conveying device described in Patent Document 2, the sheet is not conveyed along the convex guide rib before the leading end of the sheet reaches the downstream roller. Noise generation cannot be reduced.

  In other words, when the paper transported in the transport path becomes undulated and waved, when the paper passes through the curved transport path in the transport path, the seated state becomes resistance and the paper is squeezed. With respect to the problem that noise such as sound is generated, those described in Patent Documents 1 and 2 cannot solve this problem.

  The present invention has been devised to solve the above-described problems, and has as its object to squeeze the paper generated when the paper that has been waved and seated passes through the curved conveyance path in the conveyance path. It is an object of the present invention to provide a sheet conveying device, a document feeding device, and an image forming apparatus that can reliably reduce or prevent noise such as (burr noise).

  In order to solve the above problems, a paper transport device of the present invention is a paper transport device including a pair of transport guides that form a transport path for transporting paper, and a transport roller provided in the transport path, Each of the pair of conveyance guides is provided with a plurality of conveyance ribs in the sheet width direction along the sheet conveyance direction on the opposing surfaces, and the conveyance path is a curved conveyance path. And the position of the apex of the transport rib immediately before entering the curved transport path is set to a positional relationship that pushes back the wrinkled state caused by the undulation generated in the paper width direction of the paper. It is said. Here, to push back to the original state is to improve the curved state caused by the generated undulation to a more gentle curved state, and it is more preferable if the undulated state can be almost eliminated or completely eliminated, but it is not necessarily completely eliminated. There is no need.

  According to the present invention, when entering the curved conveyance path, the seating state of the sheet is reliably improved. As a result, the front end portion of the paper in the conveyance direction is smoothly curved by the conveyance ribs of the curved conveyance path and conveyed in the curved conveyance path.

  According to the invention, the transport rib of the one transport guide and the transport rib of the other transport guide are arranged shifted in the paper width direction and immediately before entering the curved transport path. The conveying ribs may be configured such that the width between the vertices facing each other is set to zero or a slight width when viewed from the paper width direction.

  According to the above configuration, the sheet can pass between the conveying ribs even when the width between the opposing vertices is zero.

  According to the present invention, the position of the apex of the transport rib immediately before entering the curved transport path in a state viewed from the paper transport direction may be substantially coincident with the nip position of the transport roller. Good.

  Further, according to the present invention, the seating portion that sits in the paper width direction with respect to the paper to be transported is provided on the upstream side of the transport path, and the portion corresponding to the seating portion in the paper width direction is provided. It is good also as a structure by which the position of the vertex of a conveyance rib was set to the said positional relationship.

  Since the seating state is caused by pulling by the front and rear rollers provided in the seating portion, the seating state occurs mainly at a location (area) corresponding to the seating portion in the sheet width direction. Therefore, if it can be improved by pushing back the seated state, noise such as squeak noise will not occur.

  Further, according to the present invention, the seating portion can be exemplified by a pick-up roller that picks up paper and a sucker roller that picks up the picked-up paper and feeds it to the transport path.

  Further, the document feeder of the present invention includes a placement tray for placing a document, a discharge tray for discharging the document, and the paper transport device for transporting the document placed on the placement tray to the discharge tray. It is characterized by having.

  The image forming apparatus of the present invention includes a document feeding device, a reading device that reads an image from a document fed by the document feeding device, and an image forming unit that forms a document image read by the reading device on a sheet. And the sheet conveying device is provided in the document conveying path of the document feeding device and / or the sheet conveying path of the image forming unit.

  According to the present invention, the position of the apex of the transport rib immediately before entering the curved transport path is set to a positional relationship that pushes back the wrinkled state caused by the waviness generated in the paper width direction of the paper to the original state. When entering the transport path, the seating state of the paper is reliably improved. As a result, the front end of the paper in the conveyance direction is smoothly curved and conveyed by the conveyance ribs of the curved conveyance path, so that it is possible to reduce or prevent the generation of noise such as a creaking sound due to the resistance of the seating.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention as viewed from the front. FIG. 6 is a partially enlarged perspective view schematically showing a state in which an upper cover of the document feeder is opened. It is a schematic sectional drawing which expands and shows the part following a curved conveyance path from the linear conveyance path of a 1st conveyance path. It is a schematic sectional drawing in alignment with the II line | wire of FIG. FIG. 6 is a schematic plan view showing a state where a document is picked up by a pickup roller and a suction roller. FIG. 6 is a schematic front view showing a state in which a document is picked up by a pickup roller and a suction roller as seen from the paper transport direction. FIG. 6 is a front view of a paper discharge roller provided at a paper discharge port.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
In the first embodiment, a case will be described in which the sheet conveying device of the present invention is applied to a document feeder mounted on an image forming apparatus.

-Description of overall configuration of image forming apparatus-
FIG. 1 is a schematic cross-sectional view of the image forming apparatus according to the first embodiment when viewed from the front.

  An image forming apparatus 1 shown in FIG. 1 includes an in-body discharge space portion formed in a U-shaped cross section between an apparatus main body 10 having an image forming unit and an image reading housing having an image reading unit 20 for a document. 13 is an in-body discharge type image forming apparatus in which 13 is formed.

  The in-body discharge space 13 is formed by an inner bottom surface 10 a, an inner side surface 10 b, and an inner back surface 10 c of the apparatus main body 10, and the upper portion of the space is closed by the image reading unit 20. A paper space is formed. An inner bottom surface 10a of the apparatus main body 10 is a sheet discharge tray 17, and a sheet discharge roller 136 described later is disposed on the inner back surface 10c.

  A document feeder (ADF) 30 is provided on the upper part of the image reading unit 20, and this document feeder 30 rotates a hinge (not shown) provided at an edge on the back side of the upper surface of the image reading unit 20. The front side is provided as a moving center so that it can be opened and closed in the vertical direction (that is, it can be opened and closed with respect to the image reading unit 20).

  In the image forming apparatus 1 having such a configuration, a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image using a single color (for example, black). The image data corresponding to is handled. The image forming unit 104 is provided with four developing devices 112 for forming four types of toner images, a photosensitive drum 113, a cleaning device 114, and four chargers 115, each of which includes black, cyan, magenta, and Corresponding to yellow, four image stations Pa, Pb, Pc, and Pd are configured.

  An intermediate transfer belt 121 is disposed on the upper side of the photosensitive drum 113. The intermediate transfer belt 121 circulates in the direction of arrow C, the residual toner is removed and collected by the belt cleaning device 125, and the toner images of the respective colors formed on the surfaces of the photosensitive drums 113 are sequentially transferred and superimposed. Thus, a color toner image is formed on the surface of the intermediate transfer belt 121.

  A nip area is formed between the transfer roller 126a of the secondary transfer device 126 and the intermediate transfer belt 121, and the sheet conveyed through the sheet conveyance path R1 is sandwiched and conveyed in the nip area. When the sheet passes through the nip area, the toner image on the surface of the intermediate transfer belt 121 is transferred and conveyed to the fixing device 117.

  The fixing device 117 sandwiches the sheet with the toner image transferred between the fixing roller 131 and the pressure roller 132 and heats and presses the sheet to fix the toner image on the sheet.

  The paper feed cassette 16 is provided below the optical scanning device 111. The paper is pulled out of the paper feed cassette 16 by the pickup roller 133a and the suction roller 133b, and is transported to the paper transport path R1. The paper discharge roller is provided in the paper discharge unit 138 via the secondary transfer device 126 and the fixing device 117. It is carried out to the paper discharge tray 17 via 136. A registration roller 134, a transport roller 135, and a paper discharge roller 136 are disposed in the paper transport path R1.

  When image formation is performed on the back side, the paper is conveyed in the reverse direction from the paper discharge roller 136 to the reverse conveyance path Rr, the front and back sides of the paper are reversed, and the paper is guided again to the registration roller 134, and Similarly, image formation is performed on the back surface, and the paper is carried out to the paper discharge tray 17.

-Description of Document Feeder 30-
The document feeder 30 includes a document tray 31 on which a document (paper) M is placed, a discharge tray 32 from which the document M is discharged, and a document M placed on the document tray 31 is conveyed to a reading position P1. The first conveyance path 33a, the second conveyance path 33b in which the document M conveyed to the reading position P1 is conveyed to the discharge tray 32, and the reversal in which the document M that has passed the reading position P1 is returned to the first conveyance path 33a. And a conveyance path 33c. The reading position P1 is a position where light is emitted from the light source 23a through the document reading glass 22 described later.

  A pickup roller 34 is provided in the vicinity of the document tray 31. The pickup roller 34 is provided for taking the document M placed on the document tray 31 into the first transport path 33a in order from the top.

  In the vicinity of the pickup roller 34, a roller roller 35 is provided. The suction roller 35 is provided to prevent the plurality of originals M from being conveyed to the first conveyance path 33a in a state where they overlap each other (double feeding).

  The path from the document tray 31 to the discharge tray 32 constituted by the first transport path 33a and the second transport path 33b includes a curved transport path 33a2 formed in a U shape when viewed from the front. Specifically, the first conveyance path 33a is formed so as to be folded back from the document tray 31 toward the reading position P1 through the linear conveyance path 33a1 and the curved conveyance path 33a2.

  The second transport path 33b is formed so as to extend from the reading position P1 to the downstream side in the transport direction (discharge tray 32 side). The reverse conveyance path 33c is provided between the first conveyance path 33a and the second conveyance path 33b, and is a path from the junction P2 with the first conveyance path 33a to the junction P3 with the second conveyance path 33b. It is. That is, a circulation path is formed by the curved conveyance path 33a2, the second conveyance path 33b, and the reverse conveyance path 33c of the first conveyance path 33a. Note that the second conveyance path 33b between the junction P3 and the discharge tray 32 functions as a switchback path for switching between the leading edge and the trailing edge of the document M in the conveyance direction.

  The first conveyance path 33a is provided with a conveyance roller pair 36a and a conveyance roller pair 36b, and the second conveyance path 33b is provided with a conveyance roller pair 36c, a conveyance roller pair 37, and a discharge roller pair 38. .

  The conveyance roller pair 37 and the discharge roller pair 38 are disposed between the junction P3 and the discharge tray 32.

  The conveyance roller pair 37 includes a driving roller 37a and a driven roller 37b. The discharge roller pair 38 includes a driving roller 38a and a driven roller 38b.

  A claw member 39 is provided in the vicinity of the junction P3. The claw member 39 is configured to open the second conveyance path 33b by being pushed up by the document M when the document M is conveyed in the conveyance direction Y3.

-Description of Image Reading Unit 20-
The image reading unit 20 includes a document table glass 21, a document reading glass 22, a light source unit 23, a mirror unit 24, and an imaging unit 25.

  The light source unit 23 includes a light source 23 a that irradiates light toward the document M, and a mirror 23 b that guides reflected light from the document M to the mirror unit 24. The mirror unit 24 includes a mirror 24a and a mirror 24b. The imaging unit 25 includes a condenser lens, a CCD (Charge Coupled Device), and the like.

  Although details are omitted, the image reading unit 20 is configured to be able to perform reading by the document fixing method and reading by the document moving method.

  The above is the description of the overall configuration of the image forming apparatus 1.

  In the first embodiment, since the paper conveying device of the present invention is mounted on the document feeder 30, the document feeder 30 will be described in more detail.

  FIG. 2 is a partially enlarged perspective view schematically showing a state in which the upper cover 40 is opened in the document feeder 30. FIG. 3 is a continuation of the first conveyance path 33a from the straight conveyance path 33a1 to the curved conveyance path 33a2. FIG. 4 is a schematic cross-sectional view taken along the line II of FIG. 3.

  The first transport path 33a is formed by a pair of transport guides 41 and 42 which are plate-like bodies, and each of the pair of transport guides 41 and 42 has transport ribs for transporting a sheet to the opposite surface. 41a and 42a are provided in parallel in the paper width direction X along the paper transport direction Y2. In the first embodiment, the pair of conveyance guides are referred to as an upper conveyance guide 41 and a lower conveyance guide 42. In this example, the upper conveyance guide 41 is shared by the upper cover 40, but may be provided separately from the upper cover 40.

  The transport rib 41a of the upper transport guide 41 and the transport rib 42a of the lower transport guide 42 are arranged so as to be shifted in the paper width direction X and are opposed to each other when viewed from the paper width direction X. The width (gap) L1 (see FIG. 4) between the apexes of 41a and 42a is set to a sufficient gap so that the paper can be conveyed smoothly with a margin. Specifically, the width (gap) L1 between the apexes of the opposed conveying ribs 41a and 42a is set to 2.5 to 3.0 mm with respect to a normal sheet thickness of about 0.1 mm.

  In such a configuration, in the first embodiment, an area immediately before entering the curved conveyance path 33a2, that is, a conveyance opposite to a certain area D1 (see FIG. 3) of the straight conveyance path 33a1 immediately before entering the curved conveyance path 33a2. The positional relationship between the vertices of the ribs 41a1 and 42a1 is set to a positional relationship that pushes back the wrinkled state caused by the undulation generated in the paper width direction X of the original M. That is, by pushing back to the original state, the seating state is improved, and the front end of the document M in the conveyance direction is set to a positional relationship that allows the curved conveyance path 33a2 to smoothly enter. Specifically, when viewed from the paper width direction X, the width L2 between the opposed vertices of the opposed conveying ribs 41a1 and 42a1 is set to zero or a slight width (for example, about 0.1 to 0.2 mm). doing. That is, except for the region D1, the width (gap) L1 is set as in the conventional case. Here, the straight conveyance path 33a1 is not a strict meaning of literally a straight line, but is a concept including a conveyance path having a very gentle curve that can convey a document with almost no bending. The curved conveyance path 33a2 is a concept including a curved conveyance path that rapidly changes the conveyance direction of the document M. For example, it is a concept including a curved conveyance path that changes the conveyance direction of the document M from the horizontal direction to the vertical direction by approximately 90 degrees.

  5 and 6 show a state where a document is picked up by the pickup roller 34 and the suction roller 35. FIG. 5 is a schematic plan view, and FIG. 6 is a schematic front view as viewed from the paper conveyance direction.

  As described in the background art, when the document M placed on the document tray 31 is picked up by one pickup roller 34 and is transported to the first transport path 33a one by one by the two roller rollers 35. Since the conveyance speed by the suction roller 35 is set slightly faster than the conveyance speed by the pickup roller 34, the document M being picked up by the pickup roller 34 is pulled by the suction roller 35. For this reason, the crease M1 enters the original M between the roller roller 35 and the pickup roller 34, and the original M is waved in the paper width direction X and is in a sitting state. That is, in this case, the combination of the pickup roller 34 and the roller roller 35 acts as a seating portion. If the straight conveyance path 33a1 enters the curved conveyance path 33a2 in this sitting state, the leading end of the document M in the conveyance direction comes into contact with the conveyance rib 41a of the upper conveyance guide 41 constituting the curved conveyance path 33a2. Because it is forced to bend from the seated state, noise such as squeak noise is generated.

  However, according to the first exemplary embodiment, the positions of the apexes of the opposed conveying ribs 41a1 and 42a1 immediately before entering the curved conveying path 33a2 are in a positional relationship in which the lumped state caused by the undulation generated in the document M is pushed back to the original state. By setting, when the leading end of the document M in the conveyance direction enters the curved conveyance path 33a2, the seating state of the document M is improved. Accordingly, the leading end portion of the document M in the conveyance direction is smoothly curved without a squeak noise by the conveyance rib 41a of the curved conveyance path 33a2, and is conveyed in the curved conveyance path 33a2.

  In addition, since the transport rib 41a of the upper transport guide 41 and the transport rib 42a of the lower transport guide 42 are arranged shifted (alternately) in the paper width direction X, in a state viewed from the paper width direction X, Even when the width (gap) L2 between the vertices of the opposite conveying ribs 41a1 and 42a1 is zero, the original M can pass between the conveying ribs 41a1 and 42a1. At this time, since the document M is slightly curved in the direction opposite to the seating direction when passing between the conveying ribs 41a1 and 42a1, the seating state of the document M is more reliably improved.

  In the first embodiment, as shown in FIGS. 3 and 4, a region D1 immediately before entering the curved conveyance path 33a2 in a state viewed from the sheet conveyance direction Y2 (however, in FIG. 4, the direction perpendicular to the sheet surface). It is preferable that the positions of the apexes of the transport ribs 41a1 and 42a1 substantially coincide with the nip position of the transport roller pair 36a provided in the straight transport path 33a1. According to this configuration, the sitting state of the document M can be improved smoothly.

  Further, in the first embodiment, the transport ribs 41a1 and 42a1 that set the positional relationship of pushing back the wrinkled state caused by the undulation generated in the document M to the original state are provided in the sheet width direction X as shown in FIGS. Only the conveying ribs 41a and 42a at the locations (areas) D2 corresponding to the pickup roller 34 and the buckling roller 35, which are the seating portions, may be provided between the apexes of the conveying ribs 41a and 42a located in the outer area D3 from the sucking roller 35. The width (gap) may remain L1 (2.5 to 30 mm) as usual. As shown in FIGS. 5 and 6, wrinkles (waist) generated on the document M are generated between the two roller rollers 35 and the one pickup roller 34. Therefore, it is sufficient to improve the sitting state generated in this portion. Therefore, in the first embodiment, the positional relationship between the apexes of the transport ribs, which is improved by pushing the seating state back to the original state, is provided at a location (area) corresponding to the seating portion in the sheet width direction. However, in the first embodiment, the region D3 is set with a slight margin on both outer sides than the roller roller 35. That is, the transport rib (specifically, the transport rib 42a1 of the lower transport guide 42) slightly outside of the roller roller 35 has the above positional relationship.

  The inventor pushes the position of the apex of the opposed conveyance ribs 41a1 and 42a1 immediately before entering the curved conveyance path 33a2 back to the original state from the undulating state generated in the paper width direction X of the document M. It has been confirmed by experiments that the squeak noise is actually eliminated by setting the positional relationship. However, in this experiment, the width (gap) L2 between the vertices of the opposed conveying ribs 41a1 and 42a1 was set to 0.2 mm.

<Embodiment 2>
In the first embodiment, the case where the paper transport device of the present invention is applied to the document feeder is illustrated, but the paper transport device of the present invention can also be applied to the paper transport path of the image forming unit.

  In other words, when the paper is picked up from the paper feed cassette 16, it can be applied similarly to the case of the document feeder 30. That is, in the second embodiment, the paper stored in the paper feed cassette 16 is picked up by the pick-up roller 133a, and conveyed one by one by the roller roller 133b to the paper transport path R1. In addition, there is a possibility that the paper will be in a seated state due to the difference in rotational speed between the pickup roller 133a and the suction roller 133b. Further, as shown in FIG. 1, the sheet conveyance path R1 includes a curved conveyance path R12 for switching the sheet conveyance direction upward after being pulled out via the roller roller 133b. Therefore, by applying the paper transport device of the present invention to the paper transport path R11 immediately before the paper feed cassette 16 to the curved transport path R12, the paper with the waist becomes the curved transport path R12 of the paper transport path R1. When entering, since the seating state of the sheet is reliably improved, it is possible to reliably reduce or prevent the generation of squeaking noise during sheet transport.

  Further, in the conveyance path in which the sheets stored in the sheet feeding cassette 16 are taken out one by one and images are formed by the image forming unit, and the sheets are discharged to the discharge tray 17 after fixing, immediately before being discharged to the discharge tray 17. A seating portion is disposed at a sheet discharge port which is an exit portion of the sheet conveyance path R1.

  FIG. 7 is a front view of the paper discharge roller 136 provided at the paper discharge port, and a seating roller 137 as a seating member is provided on both outer sides of the paper discharge roller 136 in the paper width direction so as to be coaxially rotatable. It has been. The seating roller 137 is formed to have a diameter slightly larger than the diameter of the paper discharge roller 136. As a result, when the paper N after image formation is nipped by the paper discharge roller 136 and discharged to the paper discharge tray 17, both outer portions in the paper width direction of the paper nipped by the paper discharge roller 136 are placed by the waist roller 137. The paper is lifted and the back is attached. As described above, the sheet N is seated by the seating roller 137 so that the sheet N can be reliably discharged from the sheet discharge port to the end. In this case, in double-sided printing on the paper N, the paper once discharged from the paper discharge port is not completely discharged, and the paper discharge roller 136 holds the rear end of the paper and pulls it again into the paper conveyance path R1. In this case, since the sheet N is once stiffened, the pulled-in sheet N is a curved conveyance path Rr2 (see FIG. 1) portion of the reverse conveyance path Rr. There is a possibility that a squeak noise of the paper N may be generated when entering the printer.

  Therefore, by applying the paper transport device of the present invention to the reverse transport path Rr1 portion immediately before the discharge roller 137 and the curved transport path Rr2 of the reverse transport path Rr, the sheet N with the waist is placed on the reverse transport path Rr. When entering the curved conveyance path Rr2, the seating state of the sheet is reliably improved, so that the generation of squeaking noise during sheet conveyance can be reliably reduced or prevented.

<Embodiment 3>
In the first embodiment, the paper transport device of the present invention is applied to the document feeder, and in the second embodiment, the paper transport device of the present invention is applied to the paper transport path of the image forming unit. The paper conveying apparatus of the present invention can also be applied to a post-processing apparatus that punches or sorts paper.

  Although illustration is omitted, there is a case where a curved conveyance path is also passed when the sheet is conveyed from the image forming unit to the post-processing apparatus. In this case as well, the conveyance just before entering the curved conveyance path of the post-processing apparatus What is necessary is just to apply the paper conveying apparatus of this invention to a path.

-Summary of configuration and effects of the present invention-
The paper transport device of the present invention is a paper transport device provided with a pair of transport guides that form a transport path for transporting paper, and a transport roller provided in the transport path. Each of the pair of conveyance guides is provided with a plurality of conveyance ribs in the sheet width direction along the sheet conveyance direction on the opposite surface for conveying the sheet. The conveyance path includes a curved conveyance path, and the position of the apex of the conveyance rib immediately before entering the curved conveyance path pushes back the lumped state caused by the undulation generated in the paper width direction of the paper to the original state. The configuration is set to the positional relationship.

  According to this configuration, the position of the apex of the transport rib immediately before entering the curved transport path is set to a positional relationship that pushes back the wrinkled state caused by the waviness generated in the paper width direction of the paper to the original state, thereby conveying the curved transport. When entering the road, the seating state of the paper is reliably improved. As a result, the front end portion of the paper in the conveyance direction is smoothly curved by the conveyance ribs of the curved conveyance path and conveyed in the curved conveyance path.

  Further, according to the sheet conveying apparatus of the present invention, the conveying rib of the one conveying guide and the conveying rib of the other conveying guide are arranged to be shifted in the sheet width direction. The transport rib immediately before entering the curved transport path is configured such that the width between the vertices facing each other is set to zero or a slight width when viewed from the paper width direction.

  According to this configuration, the conveyance rib of one conveyance guide and the conveyance rib of the other conveyance guide are arranged so as to be shifted in the paper width direction. Even when the width is zero, the sheet can pass between the transport ribs. At this time, the sheet is slightly curved in the direction opposite to the seating direction when passing (that is, pushed back to the original state), so the seating state of the sheet can be improved more reliably.

  Further, according to the paper transport device of the present invention, the position of the apex of the transport rib immediately before entering the curved transport path in a state viewed from the paper transport direction substantially coincides with the nip position of the transport roller. It is set as the structure.

  According to this configuration, the seating state of the paper can be smoothly improved by making the position of the apex of the transport rib substantially coincide with the nip position of the transport roller.

  In addition, according to the paper transport device of the present invention, a seating portion that sits in the paper width direction with respect to the transported paper is provided upstream of the transport path, and corresponds to the seating portion in the paper width direction. The position of the apex of the conveyance rib at the location to be set is set to the positional relationship.

  Since the seating state is caused by pulling by the front and rear rollers provided in the seating portion, the seating state occurs mainly at a location (area) corresponding to the seating portion in the sheet width direction. Therefore, noise such as a squeak is not generated if the seating state of the portion can be improved. Therefore, in the present invention, the positional relationship between the apexes of the transport ribs for improving the seating state may be provided at a location (area) corresponding to the seating portion in the sheet width direction.

  Further, according to the paper transporting apparatus of the present invention, the seating portion can be exemplified by a pick-up roller that picks up the paper and a sucker roller that picks up the picked-up paper and feeds it to the transport path. Originally, the pick-up roller and the roller roller are provided in order to reliably feed the paper placed on the tray one by one and transport it to the transport path, and are not intended to attach the back to the paper, As described above, since the conveyance speeds of the front and rear rollers are different, the sheet becomes stiff at this portion. Therefore, according to the present invention, the conveyance rib immediately before the one sheet picked up by the pickup roller and the roller roller reaches the first curved conveyance path is set to the above positional relationship, so that the sheet of the sheet when passing through the curved conveyance path is set. Squeak noise can be reliably reduced or prevented.

  Further, the document feeder of the present invention includes a placement tray for placing a document, a discharge tray for discharging the document, and the paper transport device for transporting the document placed on the placement tray to the discharge tray. It is set as the structure provided with.

  As a result, it is possible to reduce or prevent the occurrence of squeaking noise when the document is conveyed by the document feeder.

  The image forming apparatus of the present invention includes a document feeding device, a reading device that reads an image from a document fed by the document feeding device, and an image forming unit that forms a document image read by the reading device on a sheet. And the sheet conveying device is provided in the document conveying path of the document feeding device and / or the sheet conveying path of the image forming unit.

  Accordingly, it is possible to reduce or prevent the occurrence of squeaking noise during the conveyance of the paper not only in the original but also in the conveyance path from the time when the image is formed on the paper and discharged to the discharge tray.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-mentioned embodiment is only a mere illustration in all points, and should not be interpreted limitedly. The scope of the present invention is set forth in the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention is a sheet conveying apparatus, a document feeding apparatus, and an image forming apparatus that are excellent in reducing or preventing noise such as a squeak noise during sheet conveyance, and greatly contributes to sheet conveyance having a curved conveyance path.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Apparatus main body 13 In-body discharge space part 17 Discharge tray 20 Image reading part 21 Original plate glass 22 Original reading glass 23 Light source unit 24 Mirror unit 25 Image pick-up part 30 Original feeder 31 Original tray 32 Output tray 33a First transport path 33a1 Straight transport path 33a2 Curved transport path 33b Second transport path 33c Reverse transport path 34 Pickup roller 35 Sakiki roller 36a, 36b, 36c, 38 Transport roller pair 38 Discharge roller pair 40 Upper cover 41 Upper transport guide (transport guide) )
42 Lower transport guide (transport guide)
41a, 41a1, 42a, 42a1 Conveying rib 133a Pickup roller 133b Sakiaki roller 136 Paper discharge roller D1, D2, D3 Area X Document X1 皺 N Paper R1 Paper conveying path Rr Reverse conveying path R11 Paper conveying path R12 just before the curved conveying path R12 Curved conveyance path Y2 Paper conveyance direction X Paper width direction

Claims (7)

A paper transport device comprising a pair of transport guides that form a transport path for transporting paper, and a transport roller provided in the transport path,
Wherein the each of the pair of conveying guides, prior Symbol sheet conveying rib for conveying along the sheet conveying direction, has been kicked multiple set in the sheet width direction,
The transport path includes a curved transport path;
The transport rib is formed in at least a first region provided on the upstream side of the curved transport path and a second region provided on the upstream side in the paper transport direction from the first region,
The transport roller is disposed in the first region;
At least the gap between the vertices of the conveyance ribs in the nip portion of the conveyance roller in the first area is narrower than the gap between the vertices of the conveyance ribs in the second area. apparatus. The sheet conveying device according to claim 1,
The conveyance ribs of the one conveyance guide and the conveyance ribs of the other conveyance guide are arranged shifted in the paper width direction,
In the first area, the gap between the vertices of the conveying ribs facing each other is set in a range of 0 to 0.2 mm . The sheet conveying device according to claim 1 or 2,
The sheet conveying apparatus characterized in that the position of the apex of the conveying rib immediately before entering the curved conveying path substantially coincides with the nip position of the conveying roller in a state viewed from the sheet conveying direction. A paper conveying device according to any one of claims 1 to 3,
On the upstream side of the transport path, a seating portion that sits in the paper width direction with respect to the transported paper,
In the first area, the gap between the apexes of the transport ribs is an area corresponding to the seating portion in the paper width direction and is narrower than the gap between the apexes of the transport ribs in the second area. A sheet conveying apparatus characterized by the above. The sheet conveying device according to claim 4,
The sheet feeding device, wherein the seating portion is a pickup roller that picks up a sheet and a paper roller that handles the picked-up sheet and feeds it to the conveyance path.   6. The apparatus according to claim 1, further comprising: a loading tray on which the document is placed; a discharge tray that discharges the document; and the document placed on the placing tray is conveyed to the discharge tray. An original feeding apparatus comprising: the paper conveying apparatus described above.   A document feeding device; a reading device that reads an image from a document fed by the document feeding device; and an image forming unit that forms a document image read by the reading device on a sheet. An image forming apparatus comprising the sheet conveying device according to any one of claims 1 to 5 in a path and / or a sheet conveying path of the image forming unit.

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