JP3597696B2 - Paper transport device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paper transport device applicable to a document reading device, a copying machine, a printer, a facsimile device, and the like, and in particular, a document, paper such as a transfer paper, is formed by a pair of transport surfaces facing each other and spaced apart from each other. The present invention relates to a paper conveying apparatus that conveys a sheet while nipping it between a driving roller and a driven roller in a conveying path.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a document reading device, a copying machine, a printer, and a facsimile device, a sheet transport device for transporting a sheet such as a document or a transfer sheet, for example, a device shown in FIG. 7 is incorporated. In this paper transport apparatus, as shown in the figure, a pair of guide plates 101 and 102 are arranged to face each other, and a transport path 110 for transporting the paper is formed by these guide plates. In addition, the apparatus is provided with a driving roller 103 and a driven roller 104 for transporting the paper P along the transport path 110 while nipping. The drive roller 103 is arranged so that a part thereof protrudes toward the transport path 110 from the transport surface 101a of the guide plate 101, and is connected to a motor (not shown) as a drive source to generate rotational driving force from the motor. It is configured to receive and rotate. The driven roller 104 is arranged so that a part thereof protrudes from the conveying surface 102 a of the guide plate 102 toward the conveying path 110, and comes into pressure contact with the driving roller 103 side, so that the driven roller 103 rotates. It is configured to rotate following the rotation.
[0003]
[Problems to be solved by the invention]
By the way, when the so-called stiff paper or the paper curled toward the driven roller 104 (the paper curled outside in the case of FIG. 7) is transported by the paper transporting device configured as described above, the following problem occurs. there were. That is, when the sheet P having such characteristics is conveyed to the nip side of the driving roller 103 and the driven roller 104 along the conveyance path 110, as shown in FIG. The paper is not caught by the drive roller 103 and the driven roller 104 because it is caught by the boundary between the driven roller 102 and the driven roller 104, and the paper cannot be conveyed by the drive roller 103 and the driven roller 104.
[0004]
Note that such a problem tends to increase as the radius of curvature R becomes smaller when the transport path 110 is curved as shown in FIG. This problem does not occur only when the transport path 110 is curved, but also occurs when the transport path 110 is straight. In addition, not only when the driven roller 104 is provided on the outside but also when the driven roller 104 is provided on the inside, a similar problem occurs when trying to transport a stiff paper or a paper P curled inward. . Further, when the driving roller 103 and the driven roller 104 function as a pair of registration rollers, the driven roller 104 is made of polyacetal (POM), metal, or the like, and the paper P easily slides on the surface thereof. It is difficult for the driven roller 104 to grip the sheet P whose leading end portion is caught on the boundary, and the sheet P cannot be nipped by the driving roller 103 and the driven roller 104, and the sheet is conveyed. Can not.
[0005]
The present invention has been made in view of the above-described problems, and has as its object to provide a paper transport device that can reliably nip a paper and transport the paper along a transport path.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is configured such that the driving roller and the driven roller nip the sheet with the driving roller and the driven roller along a curved conveying path formed by a pair of conveying surfaces facing each other and spaced apart from each other. A paper transport device that transports the paper toward a document reading unit downstream of the rollers with respect to the paper transport,
The drive roller is provided on the inner transport surface side in the bent portion of the transport path, and the driven roller is provided on the outer transport surface side of the bent portion,
The outer peripheral surface of the driven co b is disposed so that the substantially coincides with the conveying surface of the driven roller side,
An opening is provided in the transfer surface on the side of the driven roller so that the nip portion of the driven roller faces the transfer path,
The width of the opening in the longitudinal direction of the driven roller is set to be larger by 2 to 3 mm than the driven roller on one side of the opening, and the width of the opening increases toward the transport path. The end of the opening is tapered .
[0007]
According to a second aspect of the present invention , the drive roller and the driven roller are nipped with a drive roller and a driven roller along a curved transport path formed by a pair of transport surfaces opposed to each other and separated from each other. A paper transport device that transports the paper toward a document reading unit downstream of the rollers with respect to the paper transport,
The drive roller is provided on the inner transport surface side in the bent portion of the transport path, and the driven roller is provided on the outer transport surface side of the bent portion,
The outer peripheral surface of the driven roller is disposed so as to substantially coincide with the transfer surface on the driven roller side,
An opening is provided in the transfer surface on the side of the driven roller so that the nip portion of the driven roller faces the transfer path,
The width of the opening in the longitudinal direction of the driven roller is set to be larger by 2 to 3 mm than the driven roller on one side of the opening, and the width of the opening increases toward the transport path. The end of the opening is finished in an arc shape .
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram illustrating a document reading apparatus in which an embodiment of a sheet conveying apparatus according to the present invention is incorporated. Hereinafter, prior to describing this embodiment in detail, an outline of a document reading apparatus will be described.
[0009]
This document reading apparatus takes in documents one by one from a document bundle placed on the document tray 10 in page order with the top page facing upward, reads the image information thereof, and reads the output tray 80 with the top page facing down in page order. In addition to reading single-sided originals with image information formed only on one side as well as double-sided originals with image information formed on both sides, the image information on both sides is read and the page order of the original bundle is changed. It can be discharged without changing it. Although this embodiment is an example in which it is mounted on the upper part of a copying machine, it can be applied to a scanner device, a facsimile device, and the like with a similar configuration.
[0010]
The document tray 10 is a document placement unit configured to be able to stack and place documents P having image information. A document set sensor 11 is provided at the bottom of the document tray 10 and detects the presence or absence of a document P on the document tray 10.
[0011]
A feed roller 23 is provided above the document tray 10, and feeds the document P on the document tray 10 toward the feed roller 21 and the separation roller 22. The paper feed roller 21 is driven to rotate so as to send out the document P on the document tray 10, while the separation roller 22 is disposed so as to be in sliding contact with the paper feed roller 21, and rotates in accordance with the pressure from the paper feed roller 21. The paper feed roller 21 and the separation roller 22 are configured to rotate while generating resistance. The document P is separated from the document bundle and fed to the first transport path 31. A feed sensor 24 that detects the leading end of the document P is provided at the entrance of the first transport path 31. The paper feed roller 21, the separation roller 22, the forward feed roller 23, and the like constitute a separation paper feed unit 20 that separates and feeds the documents P on the document tray 10 one by one.
[0012]
On the first transport path 31, there are provided a registration roller 51 which is driven to rotate so as to transport the document P, and a registration roller 52 which is slidably contacted and driven by the registration roller 51. The first transport path 31 has a second branch position 44 at the downstream side of the registration roller 51 where a fifth transport path extending in a substantially horizontal direction branches. At the second branch position 44, an inverting branch lever 45 is provided as second switching means for switching the transport path of the document P to the first transport path 31 or the fifth transport path 35 downstream of the second branch position 44. ing. The first transport path 31 is bent upward from the second branch position 44.
[0013]
A reversing sensor 64 for detecting the rear end of the document P conveyed through the first transport path 31 is provided near the exit of the first transport path 31. And a reversing roller 62 opposed thereto. The reversing roller 61 is configured to be rotatable in both forward and reverse directions. The reversing roller 62 is pressed against the reversing roller 61 by the reversing roller pressing means 63 so as to slidably contact the reversing roller 61, thereby sandwiching the document P together with the reversing roller 61. When the reversing roller 61 stops, the document P can be conveyed and held, and a gap is formed between the reversing roller 61 by the reversing roller pressing means 63. By being separated from the reversing roller 61 as described above, the document P between the reversing roller 61 can be placed in a free state in which the original P can move up and down without resistance. Therefore, even when the front portion and the rear portion of the document P overlap in the document reversing section 60, the document can be smoothly conveyed. This will be described in detail later.
[0014]
A reversing path 65 for switching back the document P is provided above the reversing roller 61 and the reversing roller 62. The reversing path 65 is formed in a substantially horizontal direction from a position between the reversing roller 61 and the reversing roller 62 toward a position above the sheet feeding roller 21. It has an opening 66 that opens outward from the main body of the apparatus. Therefore, in the case of the original P that is long in the transport direction, when the original P is transported to the reversing path 65 by the reversing roller 61, the rear end of the original P is held between the reversing roller 61 and the reversing roller 62. The leading edge of the document P is temporarily discharged from the opening 66 to the outside of the apparatus main body. The reversing roller 61, the reversing roller 62, the reversing sensor 64, the reversing path 65, and the like constitute a document reversing unit 60.
[0015]
The lower side between the reversing roller 61 and the reversing roller 62 branches into the above-described first transport path 31 and second transport path 32. In this branch portion, the document P can be transported from the first transport path 31 to the document reversing section 60, and when the document P is transported out of the document reversing section 60, the document P is sent to the second transport path 32. As a means for regulating the transport direction, a protruding portion 67 having an extended wall surface below the second transport path 32 is provided so as to narrow the exit of the first transport path 31.
[0016]
The second transport path 32 corresponds to the transport path of the paper transport apparatus according to the present invention, and a part of the rollers and rollers provided along the second transport path 32 is used in the paper transport apparatus according to this embodiment. It corresponds to a driving roller and a driven roller. In this device, the transport path 32 is bent so as to go from the branch portion to the lower side, and the upper transport roller 53 provided on the second transport path 32 and the upper transport roller The original P on the second transport path 32 is transported to the reading position 71 of the original reading unit 70 by the lower transport roller 55 and the lower transport roller 56 that slides and follows the lower transport roller 55. The second transport path 32 joins the above-described fifth transport path 35 on the upstream side of the upper transport roller 53, and the document P sent from the fifth transport path 35 to the second transport path 32 is also the same as described above. It is configured to be conveyed toward the reading position 71 by the upper conveyance roller 53 and the lower conveyance roller 55. The paper transport device will be described later in detail.
[0017]
Further, near the exit of the second transport path 32, that is, immediately before the reading position 71, a timing sensor 72 for detecting the leading edge and the trailing edge of the document P to be transported is provided.
[0018]
The original reading unit 70 irradiates light from an exposure lamp or the like (not shown) to the lower surface of the original P conveyed on the contact glass 73 with the upper surface of the contact glass 73 provided on the upper surface of the copying machine as a reading position 71. The reflected light is guided to an image reading mechanism (not shown) via a lens system and a reflecting mirror (not shown), and the image information on the lower surface of the document P is read.
[0019]
The document P from which image information on the lower surface has been read by the document reading unit 70 is conveyed from the reading position 71 to the third conveyance path 33. The third transport path 33 is formed in a substantially linear shape that extends obliquely upward from the reading position 71, and the original P on the third transport path 33 is separated from an intermediate roller 57 provided on the third transport path 33. And are conveyed by an intermediate roller 58 that slides and follows the roller.
[0020]
At the exit of the third transport path 33, a discharge roller 81 and a discharge roller 82 that slides and follows the discharge roller 81 are provided. The document P is positioned below the document tray 10 by the discharge roller 81 and the discharge roller 82. Is discharged to the discharge tray 80.
[0021]
The discharge tray 80 is a document discharge section on which the read document P is placed, and has a slight upward inclination when viewed from the discharge roller 81 side. The placed document P is prevented from being pushed by the discharged document P and dropping from the discharge tray 80.
[0022]
Further, the third transport path 33 has a first branch position 41 where an upwardly directed fourth transport path branches to an intermediate position between the intermediate roller 57 and the discharge roller 81. At the first branch position 41, a discharge branch lever 42 is provided as first switching means for switching the transport path of the document P to the third transport path 33 or the fourth transport path 34 downstream of the first branch position 41. I have.
[0023]
The fourth transport path 34 branches off from the third transport path 33 at the first branch position 41, and then joins the first transport path 31 on the way upstream of the registration roller 51 in the middle of the first transport path 31.
[0024]
Next, the paper transport device according to the present invention will be described in detail with reference to FIGS. FIG. 2 is a side view showing a paper transport device incorporated in the original reading device of FIG. 1, and FIG. 3 is a view when the lower transport roller (driven roller) side is viewed from the lower transport roller (drive roller) side. FIG. 4 is an enlarged sectional view in which a boundary portion between a lower transport roller (follower roller) and a transport surface is enlarged.
[0025]
This paper transport device forms a transport path formed by a pair of guide plates 321 and 322 opposed to each other and spaced apart from each other, that is, a second transport path 32. Transportable. Further, in this paper transport apparatus, the lower transport roller (drive roller) 55 is disposed so that a part thereof protrudes from the transport surface 321a of the guide plate 321 toward the transport path 110, and a motor as a drive source (shown in FIG. (Omitted) and is configured to rotate by receiving a rotational driving force from a motor, which is common to the conventional example (FIG. 7), but is greatly different in the following points. That is, in this embodiment, the lower transport roller (driven roller) 56 is arranged such that a part of the outer peripheral surface thereof substantially coincides with the transport surface 322a of the guide plate 322 (dashed line in FIG. 2). As a result, the nip NP formed by the lower transport roller 55 and the roller 56 is located on the transport surface 322a.
[0026]
Therefore, even if the stiff paper or the curled paper (the outer curled paper in FIG. 2) is conveyed to the driven roller 56 side from the upper conveying roller 53, the leading end of the original P is conveyed to the conveying surface. It can be guided to the nip portion NP by 322a and can be reliably nipped by the nip portion NP, and can be transported to the reading position 71 reliably and smoothly.
[0027]
In this embodiment, the nip portion NP coincides with the conveyance surface 322a of the guide plate 322 arranged on the roller 56 side. However, even if the nip portion NP is arranged inside the conveyance path 32, the conveyance surface As long as it is arranged near the 322a, the same effect as in the above embodiment can be obtained. According to various experiments performed by the inventor of the present invention, when a document P such as plain paper for copying (PPC paper) is transported, the amount of protrusion of the roller 56 from the transport surface 322a to the transport path 32 is 0 to 0.8 mm. It was confirmed that the same effect as above could be obtained even when the value was set within the range. In this manner, the nip portion NP between the roller 55 and the roller 56 coincides with or is located close to the conveying surface 322a on the roller 56 side, so that not only normal paper but also a characteristic of having strong stiffness and a characteristic of having curl are obtained. Even in the case of transporting the paper that is being held, the paper can be reliably nipped and transported along the transport path.
[0028]
By the way, in order for the nip portion NP of the roller 56 to face the transport path 32, it is necessary to provide an opening 322b in the transport surface 322a of the guide plate 322, but the opening in the longitudinal direction of the roller 56 (the width direction of the document P). The size relationship between the width WH of the roller 322b and the width WR of the roller 56 becomes a problem. This is because, when the width WH of the opening 322b is set to be substantially the same as or slightly larger than the width WR of the roller 56 as in the related art, the boundary between the nip portion and the non-nip portion becomes streak or There is a possibility that a problem that wrinkles occur in the part may occur.
[0029]
In order to solve such a problem, in this embodiment, as shown in FIGS. 3 and 4, the width WH of the opening 322b in the longitudinal direction of the roller 56 (the width direction of the document P) is larger than the width WR of the roller 56. Is set to be about 2 to 3 mm larger on one side of the opening 322b to solve the above problem.
[0030]
In order to solve the above problem, the opening end adjacent to the roller 56 may be finished in an arc shape such that the width WH of the opening 322b increases in the longitudinal direction of the roller 56 toward the transport path 32. (FIG. 5), and may be finished in a tapered shape (FIG. 6).
[0031]
In addition, in the above-mentioned original conveying apparatus, although a plurality of mechanisms for conveying the original P along the conveying path while nipping the original P by the rollers and the rollers are provided, only the specific rollers 55 and the rollers 56 are provided. Although the present invention is applied, the application target of the present invention is not limited to this, and a combination portion of another roller and a roller, for example, a portion of a registration roller 51 and a roller 52, and an upper conveyance roller 53 The present invention can be applied to the portion of the rollers 54 and the like, and the same effects as those of the above embodiment can be obtained.
[0032]
In the above embodiment, the case where the transport path is curved has been described. However, even when the transport path is straight, the same effects as those of the above embodiment can be obtained by applying the present invention. .
[0033]
Further, in the above description, the present invention has been described by taking as an example a paper transport apparatus applied to a document reading apparatus that reads an image of the original P while transporting the original P. However, an application target of the paper transport apparatus according to the present invention is The present invention is not limited to the original reading apparatus, but is also applicable to a paper transport apparatus used in a copying machine, a printer, a facsimile apparatus, and the like that forms an image on transfer paper.
[0034]
【The invention's effect】
As described above, since the nip portion between the drive roller and the driven roller is configured to coincide with the transport surface on the driven roller side, the leading edge of the paper conveyed along the transport path is guided to the nip portion. it is possible to reliably nip the sheet in the nip portion, Ru can be conveyed along the conveying path.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a document reading apparatus in which an embodiment of a sheet conveying apparatus according to the present invention is incorporated.
FIG. 2 is a side view showing a paper transport device incorporated in the original reading device of FIG. 1;
FIG. 3 is a perspective view when a lower transport roller (driven roller) side is viewed from a lower transport roller (drive roller) side.
FIG. 4 is an enlarged cross-sectional view in which a boundary between a lower transport roller (follower roller) and a transport surface is enlarged.
FIG. 5 is an enlarged cross-sectional view illustrating another embodiment of the sheet conveying device according to the present invention.
FIG. 6 is an enlarged cross-sectional view showing another embodiment of the sheet conveying device according to the present invention.
FIG. 7 is a diagram illustrating a conventional paper transport device.
[Explanation of symbols]
32: transport path 55: lower transport roller (drive roller)
56 ... Lower transport roller (follower roller)
321, 322 guide plate 321 a (drive roller side) transfer surface 322 a (driven roller side) transfer surface 322 b (opening NP) (of transfer surface 322 a) nip portion P document (paper)
WR: width of driven roller WH: width of opening

Claims (2)

Nipping the paper with the driving roller and the driven roller along the curved conveying path formed by the pair of conveying surfaces opposed to each other and spaced apart from each other, and the paper conveying downstream from the driving roller and the driven roller. A paper transport device that transports the paper toward the original reading portion of
The drive roller is provided on the inner transfer surface side in the bent portion of the transfer path, and the driven roller is provided on the outer transfer surface side of the bent portion,
The outer peripheral surface of the driven co b is disposed so that the substantially coincides with the conveying surface of the driven roller side,
An opening is provided in the transfer surface on the side of the driven roller so that the nip portion of the driven roller faces the transfer path,
The width of the opening in the longitudinal direction of the driven roller is set to be larger by 2 to 3 mm than the driven roller on one side of the opening, and the width of the opening is increased toward the transport path. A paper transport device with a tapered opening end . Nipping the paper with the driving roller and the driven roller along the curved conveying path formed by the pair of conveying surfaces opposed to each other and spaced apart from each other, and the paper conveying downstream from the driving roller and the driven roller. A paper transport device that transports the paper toward the original reading portion of
  The drive roller is provided on the inner transfer surface side in the bent portion of the transfer path, and the driven roller is provided on the outer transfer surface side of the bent portion,
  The outer peripheral surface of the driven roller is disposed so as to substantially coincide with the transfer surface on the driven roller side,
  An opening is provided in the transfer surface on the side of the driven roller so that the nip portion of the driven roller faces the transfer path,
  The width of the opening in the longitudinal direction of the driven roller is set to be larger by 2 to 3 mm than the driven roller on one side of the opening, and the width of the opening is increased toward the transport path. A paper transport device with an open end finished in an arc shape.

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