JP6180352B2 - Paper transport device, image forming apparatus, and paper transport method - Google Patents

Description

  The present invention relates to a sheet conveying device, an image forming apparatus including the same, and a sheet conveying method, and more particularly to an efficient arrangement of rollers for reducing friction between a sheet and a conveying guide in the sheet conveying apparatus.

  A sheet conveying device is mounted on an image forming apparatus such as a printer, a copier, a facsimile machine, a scanner, or a multifunction machine having these functions. The paper conveyance device is used for conveying a recording medium (paper) from a manual feed tray or a paper feed cassette one by one to an image forming unit, or for conveying a placed document (paper) one by one to a document reading unit. Used.

  In the paper transport device, the paper feed roller is arranged at one place in the center of the paper passing width in order to provide a function for preventing paper double feeding. Two or more transport rollers are arranged downstream of the paper feed roller in the paper transport direction in order to ensure the straight running stability of the paper. In the sheet conveying apparatus having such a configuration, when a curved sheet conveying path is provided between the sheet feeding roller and the conveying roller, the sheet is conveyed while rubbing the curved convex surface. In the following Patent Document 1, a load reducing roller (roller) that freely rotates on such a curved convex surface is provided to reduce the paper conveyance load.

JP 7-179238 A

  In the paper transport device, an external force is applied to the paper by rolling the paper feed roller, and a wave is generated in the paper width direction perpendicular to the paper transport direction before reaching the transport roller. Since the paper portion where such undulation occurs does not rub against the paper conveyance path, the effect of reducing friction by the load reducing roller disclosed in Patent Document 1 cannot be obtained. Therefore, even if the load reducing roller is arranged over the paper width as in Patent Document 1, it is difficult to sufficiently obtain the effect of the load reducing roller for a paper portion where undulation occurs.

  SUMMARY An advantage of some aspects of the invention is that a roller for reducing friction between a sheet and a conveyance guide is efficiently arranged in a sheet conveyance device.

A sheet conveying apparatus according to an aspect of the present invention is disposed at one central position in the sheet passing width, and includes a sheet feeding roller that conveys sheets one by one, and a plurality of positions downstream of the sheet feeding roller across the sheet passing width. A conveyance roller that nips and conveys the paper conveyed by the paper supply roller, a conveyance guide that forms a curved convex surface in a curved paper conveyance path between the paper supply roller and the conveyance roller, and A roller that is arranged at a plurality of locations on the surface of the conveyance guide and that freely rotates around a rotation axis extending in the sheet passing width direction, the rollers being distributed and arranged in a plurality of rows in the sheet conveyance direction, and the paper feeding It is concentrated disposed roller and sheet width across the conveying roller and connecting it triangular area of said roller in the sheet conveying immediately downstream of side column of the paper feed roller, the triangular region There are, those which are located at the same position as the paper feed roller in a direction perpendicular to the sheet conveyance direction.

  According to the present invention, the rollers are concentrated in the triangular area connecting the paper feed roller and the conveyance rollers at both ends of the sheet passing width, so that the roller for reducing friction between the sheet and the conveyance guide is provided in the sheet conveyance device. Arranged efficiently. Thereby, a larger conveyance load reduction effect can be obtained with a small number of rollers.

1 is a front cross-sectional view illustrating a structure of an image forming apparatus including a paper conveyance device according to an embodiment of the present invention. It is a front sectional view showing the structure of the document transport mechanism. FIG. 3 is a perspective view of the inside of a document transport mechanism. FIG. 6 is a diagram illustrating an arrangement relationship of a paper feed roller, a transport roller, and a roller in a document transport mechanism.

  Hereinafter, a sheet conveying apparatus, an image forming apparatus, and a sheet conveying method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function.

  The image forming apparatus 1 is schematically configured from an apparatus main body 11, a document reading device 20 disposed opposite to the apparatus main body 11, and a connecting portion 30 provided between the document reading apparatus 20 and the device main body 11. The

  The document reading device 20 is supported on the upper end portion of the connecting portion 30. The document reading device 20 includes a document reading unit 5 and a document transport unit 6.

  The document reading unit 5 includes a contact glass 161 mounted on the upper surface opening of the document reading unit housing for placing the document. The contact glass 161 includes a document fixing reading unit (not shown) that reads a placed document, and a document conveyance reading unit (not shown) that reads a document conveyed by the document conveyance unit 6. The document reading unit 5 further includes an openable / closable document pressing cover 162 for pressing a document placed on the contact glass 161, a document placed on the contact glass 161 in the document fixed reading unit, and a contact in the document transport reading unit. And a reading unit 163 that reads each image of the document conveyed onto the glass 161. The reading unit 163 optically reads an image of a document using an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and generates image data.

  The document transport unit 6 includes a document placing table 61 on which a document is placed, a document discharge unit 66 from which an image-read document is discharged, and a document transport mechanism 65. The document transport mechanism 65 includes a paper feed roller, a transport roller, and a paper reversing mechanism (not shown). The document transport mechanism 65 drives the paper feed roller and the transport roller to feed the documents placed on the document placing tray 61 one by one onto the contact glass 161 in the document transport reading unit, and then by the reading unit 163. After enabling reading, the document is discharged onto the document discharge tray 66. In addition, the document transport mechanism 65 allows the reading unit 163 to read the images on both sides of the document by causing the paper reversing mechanism to reverse the document and transport it again onto the contact glass 161 in the document transport reading unit. . The document transport mechanism 65 corresponds to the paper transport device described in the claims.

  Further, the document conveying unit 6 is provided so as to be rotatable with respect to the document reading unit 5 so that the front side thereof can move upward. By moving the front side of the document conveying unit 6 upward to open the upper surface of the contact glass 161 as a document table, a user can place a read document, for example, a book in a spread state, on the upper surface of the contact glass 161. It is like that.

  An operation unit 47 is disposed on the front surface of the document reading device 20. The operation unit 47 receives instructions such as an image forming operation execution instruction and a document reading operation execution instruction from the operator regarding various operations and processes that can be executed by the image forming apparatus 1. The operation unit 47 includes a display unit 473 that displays operation guidance to the operator.

  The apparatus main body 11 includes an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a paper discharging unit 15, and the like.

  When the image forming apparatus 1 performs a document reading operation, the document reading unit 5 optically reads a document conveyed by the document conveying unit 6 or an image of a document placed on the contact glass 161 to generate image data. To do. Image data generated by the document reading unit 5 is stored in a built-in HDD or a network-connected computer.

  When the image forming apparatus 1 performs an image forming operation, the image data generated by the document reading operation, the image data received from a user terminal device such as a computer or a smartphone connected to a network, or stored in a built-in HDD. The image forming unit 12 forms a toner image on a sheet P as a recording medium fed from the sheet feeding unit 14 based on the image data and the like. The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 12 include a photosensitive drum, a developing device that supplies toner to the photosensitive drum, a toner cartridge that stores the toner, a charging device, and an exposure device. And a primary transfer roller 126.

  When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 each receive image data. A toner image is formed on the photosensitive drum 121 by charging, exposure, and development processes based on the image composed of each color component, and the toner image is driven by the primary transfer roller 126 by the driving roller 125a and the driven roller 125b. The image is transferred onto the intermediate transfer belt 125 that is stretched around the belt.

  The intermediate transfer belt 125 is driven by a driving roller 125 a in a state where an image carrying surface on which a toner image is transferred is set on the outer peripheral surface thereof and in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 travels endlessly between the driving roller 125a and the driven roller 125b while being synchronized with each photosensitive drum 121.

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to become a color toner image. The secondary transfer roller 210 conveys the color toner image formed on the surface of the intermediate transfer belt 125 from the sheet feeding unit 14 through the conveyance path 190 at the nip N between the intermediate transfer belt 125 and the driving roller 125a. It is transferred to the paper P that has been transferred. Thereafter, the fixing unit 13 fixes the toner image on the paper P to the paper P by thermocompression bonding. The sheet P on which the color image has been formed after the fixing process is completed is discharged to the discharge tray 151.

  The paper feed unit 14 includes a plurality of paper feed cassettes including a manual feed tray 141. A control unit (not shown) rotates the pickup roller 145 of the paper feed cassette containing the paper of the size specified by the operator's instruction, and feeds the paper P contained in each paper feed cassette to the nip portion N. Transport toward

  Next, a paper conveying apparatus (original conveying mechanism 65) according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a front sectional view showing the structure of the document conveying mechanism 65. FIG. 3 is a perspective view of the inside of the document transport mechanism 65.

  The document transport mechanism 65 includes a paper feed roller 70 a and a pickup roller 75. The paper feed roller 70 a is disposed downstream of the pickup roller 75 in the paper transport direction. Further, the paper feed roller 70a is arranged at one place in the center of the paper passing width. The paper feed roller 70a and the pickup roller 75 are connected by a drive transmission member (not shown) to constitute a paper feed mechanism.

  The pickup roller 75 is a roller that picks up one sheet on the top surface of the sheet bundle by applying a friction force larger than the friction force between the stacked sheets to the top surface of the stacked sheet bundle. It is.

  The paper feed roller 70a is connected to a motor (not shown) via a drive shaft. Accordingly, when the paper feed roller 70a is driven to rotate clockwise in the drawing, the paper feed mechanism is rotated downward. The leading edge of the document placed on the document placement tray 61 is in contact with the separation wall 76, and the pickup roller 75 is in contact with the uppermost sheet as the paper feeding mechanism is rotated downward.

  A separation pad 70b is disposed to face the paper feed roller 70a. A conveyance nip is formed by the sheet feeding roller 70a and the separation pad 70b. When the document bundle picked up by the pickup roller 75 enters the conveyance nip, the overlapped sheets are separated one by one and conveyed downstream by the sheet feeding roller 70a.

  Conveying rollers 80a are arranged at a plurality of locations across the width of the sheet passing downstream of the sheet feeding roller 70a. The driven roller 80b is in contact with the conveying roller 80a, and a nip portion is formed by the conveying roller 80a and the driven roller 80b. The transport roller 80a is rotationally driven by a motor (not shown). As a result, the transport roller 80a nips the paper transported by the paper feed roller 70a at the nip formed between the driven roller 80b and transports the paper to the document transport reading unit 51.

  A curved sheet conveying path 100 is formed between the sheet feeding roller 70a and the conveying roller 80a. The paper conveyed by the paper supply roller 70a passes through the paper conveyance path 100 and reaches the conveyance roller 80a.

  The conveyance guide 90 forms the lower surface of the paper conveyance path 100, that is, a curved convex surface. Rollers 91 that freely rotate around a rotation axis extending in the sheet passing width direction are arranged at a plurality of locations on the surface of the conveyance guide 90. That is, the roller 91 functions as a load reduction roller that reduces the conveyance load of the sheet conveyed while rubbing the curved convex surface of the conveyance guide 90.

  In the conveyance guide 90, a large number of curved guide ribs 90a are arranged in the sheet passing width direction. The tips of the guide ribs 90a form the curved convex surface as a whole.

  FIG. 4 is a diagram illustrating an arrangement relationship between the paper feed roller 70 a, the transport roller 80 a, and the roller 91 in the document transport mechanism 65. The rollers 91 are concentrated in a substantially area (hereinafter simply referred to as an area) of the triangle 101 connecting the paper feed roller 70a and the conveyance rollers 80a at both ends of the sheet passing width. The sheet is nipped at the center of the sheet passing width by the sheet feeding roller 70a, and is nipped by the entire sheet passing width at the transport roller 80a. Accordingly, the paper portion corresponding to the triangle 101 is subjected to tension by the paper feed roller 70a and the transport roller 80a, and thus undulation is unlikely to occur. On the other hand, since the tension is not applied to the other paper portions, undulation can occur. For this reason, by arranging the rollers 91 in the area of the triangle 101 in a concentrated manner, a larger transport load reduction effect can be obtained with a small number of rollers 91.

  As a method of arranging the rollers 91, as shown in FIG. 4, the rollers 91 can be distributed in a plurality of rows. In this case, for example, one roller is arranged in the upstream row and three rollers 91 are arranged in the downstream row so that the upstream row width is narrow and the downstream row width is wide. . As a result, the rollers 91 can be concentrated in the region of the triangle 101. As described above, when the rollers 91 having the same dimensions are used, the column width can be arbitrarily adjusted only by changing the arrangement number.

  In addition, you may change the dimension of the roller 91 for every row | line | column. For example, the rollers 91 having a longer width than the rollers 91 arranged in the upstream row may be arranged in the downstream row. Further, the number of columns is not limited to 2, and may be 3 or more.

  In this way, the rollers 91 and the conveying rollers at both ends of the sheet passing width are concentratedly arranged in a triangular area, and the sheet is conveyed by the pickup roller 75, the rollers 91, and the conveying roller 80a.

  As described above, according to the present embodiment, the rollers 91 for reducing friction between the document (paper) and the conveyance guide 90 are efficiently arranged in the paper conveyance mechanism 65. Thereby, a larger conveyance load reduction effect can be obtained with a small number of rollers 91.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above-described embodiment, an example in which the paper transport device according to the present invention is mounted on a multifunction peripheral is described. However, this is only an example, and the paper transport device according to the present invention may be another electronic device, for example, It can be mounted on a printer device, a copier, a facsimile device, a scanner device, or the like.

  Moreover, in the said embodiment, the structure and process which were shown by the said embodiment using FIG. 1 thru | or FIG. 4 are only one Embodiment of this invention, and are not the meaning which limits this invention to the said structure and process.

65 Document transport mechanism (paper transport device)
70a Paper feed roller 80a Transport roller 90 Transport guide 91 Roller 100 Paper transport path

Claims (5)

A paper feed roller disposed at one central portion of the paper passing width and transporting paper one by one;
A conveying roller that is disposed at a plurality of locations across the sheet passing width downstream of the sheet feeding roller and nips and conveys the sheet conveyed by the sheet feeding roller;
A conveyance guide that forms a curved convex surface in a curved sheet conveyance path between the sheet feeding roller and the conveyance roller;
A roller disposed at a plurality of locations on the surface of the conveyance guide and freely rotating around a rotation axis extending in the sheet passing width direction;
The rollers are distributed and arranged in a plurality of rows in the paper transport direction, and are concentrated in a triangular area connecting the paper feed roller and the transport rollers at both ends of the paper passing width .
The sheet conveying device in which the rollers in the row immediately after the sheet conveying downstream side of the sheet feeding roller are arranged at the same position as the sheet feeding roller in the direction orthogonal to the sheet conveying direction in the triangular area .   The sheet conveying device according to claim 1, wherein the rollers are arranged in a plurality of rows, the row width on the upstream side is narrow, and the row width on the downstream side is widened.   The sheet conveying apparatus according to claim 1, wherein all the dimensions of the rollers are the same.   An image forming apparatus comprising the sheet conveying device according to claim 1. A paper feed roller disposed at one central portion of the paper passing width and transporting paper one by one;
A conveying roller that is disposed at a plurality of locations across the sheet passing width downstream of the sheet feeding roller and nips and conveys the sheet conveyed by the sheet feeding roller;
A conveyance guide that forms a curved convex surface in a curved sheet conveyance path between the sheet feeding roller and the conveyance roller;
A roller that is disposed at a plurality of locations on the surface of the conveyance guide and that freely rotates about a rotation axis extending in the sheet passing width direction.
The roller, is arranged to be distributed on a plurality of rows in the sheet conveyance direction, and concentrated arranged in the paper feed roller and the sheet width across the conveying roller and connecting it triangular area of further sheet conveyance of the paper feed roller The rollers in the row immediately downstream are arranged in the triangular area at the same position as the paper feed roller in the direction orthogonal to the paper transport direction , and the paper is transported by these paper feed rollers, rollers, and transport rollers. Paper transport method.