JP2019218184A - Sheet conveying apparatus and image forming apparatus equipped with the same - Google Patents

Abstract

To provide a sheet conveying apparatus capable of guiding a sheet conveyed to a sheet conveying path to the vicinity of a pair of conveyance rollers while preventing the sheet conveying path in a pair of conveyance guide members from interfering with respect to the pair of conveyance rollers, and an image forming apparatus including the same.SOLUTION: The sheet conveying apparatus includes a pair of conveyance guide members forming a sheet conveying path for conveying a sheet, and a pair of conveyance rollers provided in the sheet conveying path for conveying the sheet. The pair of conveyance guide members includes a first sheet conveyance region which is a conveyance region of a sheet including portions of a pair of conveyance rollers, and a second sheet conveyance region which is a conveyance region of sheets other than portions of the pair of conveyance rollers. The interval between the pair of conveyance guide members in the second sheet conveyance region is narrower than the distance between the pair of conveyance guide members in the first sheet conveyance region.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus including the same, such as a copier, a multifunction peripheral, and a printer.

  In a sheet transport apparatus including a pair of transport guide members and a pair of transport rollers, the pair of transport guide members form a sheet transport path for transporting a sheet such as a sheet. The pair of transport rollers are provided in the sheet transport path and transport the sheet.

  In such a sheet conveying apparatus, in order to prevent the sheet conveying path of the pair of conveying guide members from obstructing the pair of conveying rollers, the interval between the pair of conveying guide members is set such that the sheet conveying path has the pair of conveying rollers. It needs to be wide enough so as not to interfere with the rollers. However, if the distance between the pair of conveyance guide members is too large, the sheet conveyed to the sheet conveyance path tends to rush into a place away from the nip portion of the pair of conveyance rollers. Then, the leading end of the sheet is damaged, and furthermore, the sheet is jammed (jam). Therefore, it is desired that the sheet conveyed to the sheet conveyance path be guided to the vicinity of the nip portion of the pair of conveyance rollers while the sheet conveyance path in the pair of conveyance guide members does not interfere with the pair of conveyance rollers.

  In this regard, Patent Literature 1 discloses a configuration in which a pair of conveyance guide members that form a sheet conveyance path for conveying a sheet conveyed by a plurality of pairs of conveyance rollers have the width of both ends narrower toward the center. Has been disclosed.

International Publication No. WO 2016/031410

  However, the configuration described in Japanese Patent Application Laid-Open No. H11-163572 discloses a configuration in which a sheet conveyed to a sheet conveyance path is prevented from being hindered by a pair of conveyance rollers. It is not designed to lead to the vicinity of.

  Therefore, the present invention is a sheet conveying apparatus including a pair of conveying guide members forming a sheet conveying path for conveying a sheet, and a pair of conveying rollers provided on the sheet conveying path and conveying the sheet. A sheet conveying device capable of guiding a sheet conveyed to the sheet conveying path to the vicinity of a nip portion of the pair of conveying rollers while preventing a sheet conveying path of the pair of conveying guide members from obstructing the pair of conveying rollers; It is an object of the present invention to provide an image forming apparatus having the same.

  In order to solve the above problems, a sheet conveying device according to the present invention includes a pair of conveying guide members forming a sheet conveying path for conveying a sheet, and a pair of conveying guide members provided in the sheet conveying path and conveying the sheet. A pair of transport guide members, wherein the pair of transport guide members includes a first sheet transport area that is a transport area of the sheet including the pair of transport rollers, and a pair of transport rollers. And a second sheet transport area that is a transport area of the sheet other than the portion, wherein the distance between the pair of transport guide members in the second sheet transport area is equal to the distance It is characterized by being narrower than the interval. Further, an image forming apparatus according to the present invention includes the sheet conveying device according to the present invention.

  According to the present invention, it is possible to guide the sheet conveyed to the sheet conveyance path to the vicinity of the nip portion of the pair of conveyance rollers while preventing the sheet conveyance path of the pair of conveyance guide members from obstructing the pair of conveyance rollers. It becomes possible.

FIG. 2 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment as viewed from the front. FIG. 2 is a schematic plan view schematically illustrating a sheet conveyance state in the sheet conveyance device according to the first embodiment. FIG. 3 is a schematic sectional view taken along lines A1-A1, A2-A2, and A3-A3 of the example of the sheet conveying apparatus shown in FIG. FIG. 9 is a schematic plan view schematically showing a sheet conveyance state in a conventional sheet conveyance device. FIG. 5 is a schematic sectional view taken along line B1-B1 of the example of the sheet conveying apparatus shown in FIG. 4. FIG. 7 is a schematic cross-sectional view of another example of the sheet conveying apparatus illustrated in FIG. 2 along the line A1-A1, the line A2-A2, and the line A3-A3. FIG. 13 is a schematic cross-sectional view taken along lines A1-A1, A2-A2, and A3-A3 of still another example of the sheet conveying apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed description thereof will not be repeated.

[Image forming apparatus]
FIG. 1 is a schematic sectional view of the image forming apparatus 100 according to the present embodiment as viewed from the front. An image forming apparatus 100 shown in FIG. 1 forms a monochrome image on a sheet P such as a recording sheet in accordance with image data read by a document reading device 108 or image data transmitted from the outside. An image forming apparatus. Note that the image forming apparatus 100 may be a color image forming apparatus.

  The image forming apparatus 100 includes a document reader 108 and an image forming apparatus main body 110. The image forming apparatus main body 110 is provided with an image forming unit 102 and a sheet conveying system 103.

  The image forming unit 102 includes an exposure unit 1, a developing unit 2, a photosensitive drum 3 acting as an electrostatic latent image carrier, a cleaning unit 4, a charging unit 5, a transfer unit 6, and a fixing unit 7. The sheet transport system 103 includes a paper feed tray 81, a manual paper feed tray 82, and a discharge tray 14.

  An original mounting table 92 made of transparent glass on which the original G is mounted is provided above the image forming apparatus main body 110, and an optical unit 90 for reading the original G is provided below the original mounting base 92. I have. A document reading device 108 is provided above the document table 92. The image of the document G read by the document reading device 108 is sent to the image forming apparatus main body 110 as image data, and the image formed based on the image data in the image forming apparatus main body 110 is recorded on the sheet P.

  A main sheet conveying path for guiding the sheet P sent from the paper feed tray 81 or the manual paper feed tray 82 to the discharge tray 14 via the transfer roller 61 and the fixing unit 7 in the transfer unit 6 is provided to the image forming apparatus main body 110. Wa is provided. In the vicinity of the main sheet conveyance path Wa, pickup rollers 11a and 11b, registration rollers 13, transfer roller 61, heat roller 71 and pressure roller 72 in fixing unit 7, a pair of conveyance rollers 12a and 12b, and a pair of discharge rollers 31a. , 31b.

  The image forming apparatus 100 further includes a sheet conveying device 200. The sheet conveyance device 200 includes a pair of conveyance guide members 21 and 22 and a pair of conveyance rollers 12a and 12b. The pair of conveyance guide members 21 and 22 form a sheet conveyance path W for conveying the sheet P. The pair of transport rollers 12a and 12b are provided in the sheet transport path W and transport the sheet P. In this example, a part of the main sheet conveying path Wa constitutes the sheet conveying path W. The pair of transport rollers 12a and 12b are provided on the main sheet transport path Wa such that the nip portion N is located at a central portion in the orthogonal direction V orthogonal to the surface of the sheet P of the main sheet transport path Wa. On one transport guide member 21, one transport roller 12a and one discharge roller 31a are provided rotatably about an axis. On the other transport guide member 22, the other transport roller 12b and the other discharge roller 31b are provided rotatably around the axis. The pair of transport rollers 12a and 12b and the pair of discharge rollers 31a and 31b are driven to rotate by a rotation drive unit (not shown). The sheet conveying device 200 rotates the pair of conveying rollers 12a and 12b and the pair of discharge rollers 31a and 31b in the forward direction. After the sheet conveying device 200 is stopped by passing the pair of discharge rollers 31a and 31b through the pair of conveying rollers 12a and 12b in a state where the sheet P conveyed to the one side S1 in the conveying direction S of the sheet P is sandwiched. Then, the pair of transport rollers 12a and 12b and the pair of discharge rollers 31a and 31b are rotated in opposite directions. Then, the sheet conveying device 200 passes the sheet P conveyed (switched back) to the other side S2 in the conveying direction S again through the pair of conveying rollers 12a and 12b.

  In forming an image, the image forming apparatus 100 supplies the sheet P from the paper feed tray 81 or the manual paper feed tray 82 and conveys the sheet P to the registration rollers 13. Next, the sheet P is conveyed by the transfer roller 61 at a timing when the sheet P and the toner image on the photosensitive drum 3 rotated in the rotation direction C are aligned, and the toner image is transferred onto the sheet P. Thereafter, the unfixed toner on the sheet P is melted and fixed by heat by passing the sheet P through the heat roller 71 and the pressure roller 72 in the fixing unit 7, and the conveying rollers 12a and 12b and the pair of discharge rollers 31a and 31b are used. Through the discharge tray 14.

  The image forming apparatus main body 110 is provided with a sub-sheet conveying path Wb. The sub-sheet conveyance path Wb is guided from the branch portion Wc of the main sheet conveyance path Wa to the upstream side of the registration rollers 13 of the main sheet conveyance path Wa so that the front and back of the sheet P are reversed. In the vicinity of the sub-sheet conveyance path Wb, reverse conveyance rollers 12c and 12d are provided. A branch claw T is provided near the branch portion Wc. The branching pawl T has a first switching posture (a posture shown in FIG. 1) for guiding the sheet P from the fixing unit 7 to the pair of discharge rollers 31a and 31b, and a sheet P for switching back from the pair of discharge rollers 31a and 31b. And a second switching posture for guiding the second sheet to the sub-sheet conveying path Wb.

  When performing image formation not only on the front surface of the sheet P but also on the back surface, the rear end of the sheet P conveyed to the one side S1 in the conveyance direction S in a state where the branch claw T is switched to the first switching posture is a pair. After passing through the transport rollers 12a and 12b, the sheet P is temporarily stopped. Then, the branch pawl T is switched to the second switching posture, and the sheet P is conveyed in the opposite direction from the pair of discharge rollers 31a, 31b toward the sub-sheet conveying path Wb. The sheet P is turned over and guided again to the registration roller 13, and a toner image is formed and fixed on the back surface of the sheet P in the same manner as the front surface of the sheet P, and then discharged to the discharge tray 14.

(1st Embodiment)
FIG. 2 is a schematic plan view schematically illustrating a state of conveying the sheet P in the sheet conveying apparatus 200 according to the first embodiment. FIG. 3 is a schematic cross-sectional view taken along the line A1-A1, the line A2-A2, and the line A3-A3 of the example of the sheet conveying device 200 shown in FIG.

  As shown in FIG. 2, the pair of conveyance guide members 21 and 22 include a predetermined first sheet conveyance area α that is a conveyance area of the sheet P including a pair of the conveyance rollers 12a and 12b, and a pair of conveyance rollers 12a. , 12b and a predetermined second sheet conveying area β which is a conveying area of the sheet P. The first sheet conveyance area α and the second sheet conveyance area β are divided in the rotation axis direction H of the pair of conveyance rollers 12a and 12b. As shown in FIG. 3, the interval db between the pair of transport guide members 21 and 22 in the second sheet transport area β is smaller than the interval da between the pair of transport guide members 21 and 22 in the first sheet transport area α.

  According to the present embodiment, the second sheet transport area β is a sheet transport area other than the pair of transport rollers 12a and 12b. Therefore, even if the interval db between the pair of transport guide members 21 and 22 in the second sheet transport area β is smaller than the interval da between the pair of transport guide members 21 and 22 in the first sheet transport area α, the sheet transport path W Does not interfere with the pair of transport rollers 12a and 12b. On the other hand, the interval da between the pair of transport guide members 21 and 22 in the first sheet transport area α is wider than the interval db between the pair of transport guide members 21 and 22 in the second sheet transport area β. Therefore, also in the first sheet conveyance area α, it is possible to effectively prevent the sheet conveyance path W from obstructing the pair of conveyance rollers 12a and 12b. Therefore, the sheet P conveyed to the sheet conveyance path W is guided to the vicinity of the nip portion N of the pair of conveyance rollers 12a and 12b while the sheet conveyance path W does not interfere with the pair of conveyance rollers 12a and 12b. Can be. Thereby, the leading end of the sheet P can be hardly damaged, and further, the jam (jam) of the sheet P can be hardly generated.

  By the way, when a sheet is switched back (reversely conveyed) in the conventional sheet conveying apparatus, there are the following inconveniences.

  FIG. 4 is a schematic plan view schematically showing a state of conveying a sheet P in the conventional sheet conveying apparatus 200x. FIG. 5 is a schematic sectional view taken along line B1-B1 of an example of the sheet conveying device 200x shown in FIG.

  As shown in FIG. 4, in the conventional sheet conveying device 200x, in the sheet conveying path Wx of the pair of conveying guide members 21x and 22x, on one side S1 in the conveying direction S, upstream from the pair of conveying rollers 12a and 12b. The first interval dx1 of the sheet transport path Wx1 on the side is smaller than the second interval dx2 of the sheet transport path Wx2 on the downstream side. In addition, inclined portions 21ax and 22ax are provided near the pair of transport rollers 12a and 12b in the sheet transport path Wx1 on the upstream side. The inclined portions 21ax and 22ax are inclined such that the first interval dx1 of the sheet conveying path Wx2 becomes narrower toward the pair of conveying rollers 12a and 12b. For this reason, when the sheet P conveyed to the other side S2 in the conveyance direction S passes through the pair of conveyance rollers 12a and 12b, the sheet P easily collides with the sheet conveyance path Wx1 on the upstream side of the first interval dx1. Then, the leading end of the sheet P is damaged, and furthermore, the sheet P is jammed.

  In this regard, in the sheet conveying apparatus 200 according to the first embodiment, as shown in FIG. 3, one side S1 in the conveying direction S of the interval da between the first sheet conveying areas α in the pair of conveying guide members 21 and 22. , The first interval da1 of the upstream sheet transport path W1 is equal to the second interval da2 of the downstream sheet transport path W2. Also, of the interval db between the second sheet transport areas β in the pair of transport guide members 21 and 22, the first interval db1 of the upstream sheet transport path W1 and the downstream sheet transport path on one side S1 in the transport direction S. The second interval db2 of W2 is equal.

  By doing so, not only when the sheet P is passed from one direction (one side S1) in the transport direction S to the pair of transport rollers 12a and 12b, but also the direction opposite to the one direction in the transport direction S (the other side S2). Also, when the sheet P is passed through the pair of conveying rollers 12a and 12b, the sheet P can be less likely to collide with the sheet conveying path W1 on the upstream side of the first intervals da1 and db1. Thereby, the leading end of the sheet P can be hardly damaged, and further, the jam (jam) of the sheet P can be hardly generated.

  In the present embodiment, as shown in FIG. 3, the second sheet conveyance area β in the pair of conveyance guide members 21 and 22 has inclined portions 21a and 22a. The inclined portions 21a and 22a are provided at both ends in the transport direction S of the second sheet transport area β. The inclined portions 21a and 22a are inclined such that the distance between the pair of transport guide members 21 and 22 decreases toward the pair of transport rollers 12a and 12b. The inclined end points Q, Q where the interval between the inclined portions 21a, 22a is the narrowest are located at the outer peripheral positions of the pair of transport rollers 12a, 12b in the transport direction S of the sheet P or at positions outside the outer peripheral positions.

  In this way, the sheet P conveyed to the sheet conveying path W can be smoothly guided to the nip N between the pair of conveying rollers 12a and 12b. In this example, the one inclined portion 21a and the other inclined portion 22a have the same inclination angle with respect to the transport direction S.

  In the present embodiment, as shown in FIG. 2, a plurality of pairs (two pairs in this example) of the pair of transport rollers 12a and 12b are provided at intervals in the rotational axis direction H, and a plurality of pairs of transport rollers (12a) are provided. , 12b) and (12a, 12b). The second sheet transport area β has an intermediate area β1 and both side areas β2. The intermediate area β1 is an area between a plurality of pairs of transport rollers (12a, 12b) and (12a, 12b). The both side regions β2 are regions on both outer sides in the rotation axis direction H of the plurality of pairs of transport rollers (12a, 12b) and (12a, 12b). Then, as shown in FIG. 3, the distance db (dbβ1) between the pair of transport guide members 21 and 22 in the intermediate region β1 is equal to the distance db (dbβ2) between the pair of transport guide members 21 and 22 in both side regions β2.

  In this way, the sheet P can be stably conveyed in the sheet conveyance path W in the intermediate area β1 and the both side areas β2.

(2nd Embodiment and 3rd Embodiment)
By the way, in the second sheet conveyance area β, the distance db between the pair of conveyance guide members 21 and 22 is smaller than the distance da between the pair of conveyance guide members 21 and 22 in the first sheet conveyance area α. Are more likely to come into contact with the conveyance guide members 21 and 22 than in the first sheet conveyance area α. For this reason, a load is likely to be applied to the sheet P conveyed to the sheet conveyance path W in the second sheet conveyance area β. Therefore, in the second sheet conveyance area β, it is desired to reduce the chance that the sheet P comes into contact with the pair of conveyance guide members 21 and 22.

  In this regard, the sheet conveying apparatuses 200 and 200 according to the second and third embodiments have configurations as shown in FIGS. 6 and 7, respectively.

(2nd Embodiment)
FIG. 6 is a schematic cross-sectional view taken along line A1-A1, line A2-A2, and line A3-A3 of another example of the sheet conveying apparatus 200 shown in FIG.

  As shown in FIG. 6, in the sheet conveying apparatus 200 according to the second embodiment, the distance db (dbβ2) between the pair of conveying guide members 21 and 22 in both side regions β2 is such that the pair of conveying guide members 21 and 22 in the intermediate region β1. Is wider than the interval db (dbβ1).

  In this way, in the second sheet conveyance area β, the chance that the sheet P comes into contact with the pair of conveyance guide members 21 and 22 can be reduced. Therefore, the load on the sheet P conveyed to the sheet conveyance path W in the second sheet conveyance area β can be reduced accordingly.

(Third embodiment)
FIG. 7 is a schematic cross-sectional view taken along lines A1-A1, A2-A2, and A3-A3 of still another example of the sheet conveying apparatus 200 shown in FIG.

  As shown in FIG. 7, in the sheet conveying apparatus 200 according to the third embodiment, the distance db (dbβ1) between the pair of conveying guide members 21 and 22 in the intermediate region β1 is equal to the pair of conveying guide members 21 and 22 in both side regions β2. Is wider than the interval db (dbβ2).

  In this way, in the second sheet conveyance area β, the chance that the sheet P comes into contact with the pair of conveyance guide members 21 and 22 can be reduced. Therefore, the load on the sheet P conveyed to the sheet conveyance path W in the second sheet conveyance area β can be reduced accordingly.

(Other embodiments)
In the first to third embodiments, the sheet conveyance device 200 is provided at a position (switchback conveyance path) where the sheet P is conveyed to the one side S1 and the other side S2 in the conveyance direction S. The sheet conveying device 200 may be provided at a position where the sheet is conveyed in one direction in the conveying direction S. Further, although the sheet conveying apparatus 200 conveys the sheet as the sheet P, the sheet conveying apparatus 200 may convey the document G.

  The present invention is not limited to the embodiments described above, but can be implemented in other various forms. Therefore, such an embodiment is merely an example in every respect and should not be interpreted in a limited manner. The scope of the present invention is defined by the appended claims, and is not limited by the text of the specification. Furthermore, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

100 Image forming apparatus 12a Transport roller 12b Transport roller 200 Sheet transport apparatus 21 Transport guide member 22 Transport guide member 21a Inclined portion 22a Inclined portion 31a Discharge roller 31b Discharge roller P Sheet Q Inclined end point S Conveyance direction S1 One side S2 Other side W Sheet Conveying path W1 Upstream sheet conveying path W2 Downstream sheet conveying path da Interval da1 First interval da2 Second interval db Interval db1 First interval db2 Second interval α First sheet transport area β Second sheet transport area β1 Middle Area β2 Both sides area

Claims (6)

A sheet transport device including a pair of transport guide members forming a sheet transport path for transporting a sheet, and a pair of transport rollers provided on the sheet transport path and transporting the sheet,
The pair of conveyance guide members includes a first sheet conveyance region that is a sheet conveyance region including the pair of conveyance rollers, and a second sheet that is a sheet conveyance region other than the pair of conveyance rollers. Having a transport area,
A sheet conveying device, wherein a distance between the pair of conveying guide members in the second sheet conveying region is smaller than a distance between the pair of conveying guide members in the first sheet conveying region. The sheet conveying device according to claim 1, wherein:
A sheet transport apparatus, wherein the sheet is passed through the pair of transport rollers in one direction in the transport direction of the sheet, and is passed through the pair of transport rollers in a direction opposite to the one direction in the transport direction. The sheet conveying device according to claim 1 or 2, wherein:
The second sheet conveyance region in the pair of conveyance guide members has an inclined portion that is inclined so that the interval between the pair of conveyance guide members becomes smaller toward the pair of conveyance rollers, and the interval between the inclined portions is reduced. The sheet conveying apparatus according to claim 1, wherein the narrowest inclined end point is located at an outer peripheral position of the pair of conveying rollers in the conveying direction of the sheet or at a position outside the outer peripheral position. The sheet conveying device according to any one of claims 1 to 3, wherein
The pair of transport rollers, a plurality of pairs are provided at intervals in the rotation axis direction to constitute a plurality of pairs of transport rollers,
The second sheet conveyance area has an intermediate area between the plurality of pairs of conveyance rollers, and both outer side areas in the rotation axis direction of the plurality of pairs of conveyance rollers,
The interval between the pair of transport guide members in the intermediate region is equal to the interval between the pair of transport guide members in the both side regions, or the interval between the pair of transport guide members in the intermediate region is the pair in the both side regions. A sheet conveying device which is wider than an interval between the conveying guide members. The sheet conveying device according to any one of claims 1 to 3, wherein
The pair of transport rollers, a plurality of pairs are provided at intervals in the rotation axis direction to constitute a plurality of pairs of transport rollers,
The second sheet conveyance area has an intermediate area between the plurality of pairs of conveyance rollers, and both outer side areas in the rotation axis direction of the plurality of pairs of conveyance rollers,
A sheet conveying device, wherein a distance between the pair of conveying guide members in the both side regions is wider than a distance between the pair of conveying guide members in the intermediate region.   An image forming apparatus, comprising: the sheet conveying device according to claim 1.

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