JP2013129536A - Document feeding device and image forming apparatus having the same mounted thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document feeding device capable of stably conveying documents while shortening a distance between the respective documents, and to provide an image forming apparatus having the same mounted thereon.SOLUTION: A document feeding device includes a one-way clutch provided at a driving pulley 50 of a discharge roller 42, not transmitting a torque to the discharge roller 42 and a conveyance roller 48 when a reverse roller 44 is rotated in a direction for placing a document read at a reading position 39 on a reverse tray 23, and transmitting a torque for delivering the document conveyed in a pre-discharge conveyance passage 47 to a discharge tray 24 to the discharge roller 42 and the conveyance roller 48 when rotated in the opposite direction, in other words, when the reverse roller 44 is rotated in a direction for switching back the document placed on the reverse tray 23.

Description

  The present invention relates to a document feeding device that transports a document to a predetermined image reading position and an image forming apparatus equipped with the document feeding device.

This type of image forming apparatus is equipped with a document feeder and a reading unit, and a document set on a document tray of the document feeder is conveyed toward an image reading position of the reading unit, and an image surface thereof is read. .
In an image forming apparatus using an electrophotographic process, a photosensitive drum is charged in advance and an electrostatic latent image is formed by irradiating the surface of the drum with laser light. Next, the developed toner image is transferred and fixed on a sheet.

The document conveyed from the document tray is sent to the discharge tray of the document feeder. When reading both the front and back sides of the document, the front and back sides are reversed after the front side is read, and the back side is read. It is sent to the discharge tray.
Here, if the sheet is sent to the discharge tray while the back surface is read, the sheets are stacked on the discharge tray in the reverse order to the order set on the document tray. For this reason, a technique is disclosed in which the front and back sides are further reversed and then sent to the discharge tray (see, for example, Patent Document 1).

  Specifically, this technology is provided with a reversing tray and a switchback conveyance path. The reversing tray places the document after reading the back side, and the switchback conveyance path is reversed independently of the path for reading the document. The tray and the discharge tray are directly connected to each other, and the tray has a curved shape with a small curvature. As a result, the document whose back side is also read can be sent to the discharge tray in the order in which it is set on the document tray because the front and back sides are further reversed when passing through the switchback conveyance path from the reverse tray.

JP 2002-111956 A

By the way, the above-described conventional technique has a problem that the period required for reading all the originals becomes long.
In other words, the reversing tray of the technology is provided with a reversing roller, and the discharging tray is provided with a discharging roller. These rollers are integrally driven. In other words, in this structure, the subsequent document cannot be conveyed to the reverse tray unless the previous document is discharged to the discharge tray, and the distance between the previous document and the subsequent document is long. Because it becomes.

As described above, in this technique, there remains a problem with respect to efficiently functioning a plurality of rollers configured to be integrally driven.
In order to solve the problem of shortening the distance between the originals, the original document that is directed from the reverse tray to the discharge tray via the switchback conveyance path and the original document that is directed from the reading unit to the reverse tray are: Also, it should be noted that it may be transported face-to-face.

Even if the original document is conveyed from the reverse tray to the switchback conveyance path and the subsequent original document is conveyed to the reverse tray and the distance between the original documents is shortened, The subsequent document is jammed immediately before the reversing tray, and the productivity related to document conveyance is also deteriorated.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems and provide a document feeding device capable of stably transporting a document while shortening the distance between the documents and an image forming apparatus equipped with the document feeding device.

A first invention for achieving the above object is a document feeding device that feeds a document conveyed from a document tray, reversed and read by a reading unit to a discharge tray by a discharge roller.
Then, a conveyance path for conveying the document from the document tray toward the reading unit, a reversing unit for switching back the document read by the reading unit and changing the conveyance direction, and driving of a driving device for driving the discharge roller When the document whose one side is read by the reading unit is transported to the reversing unit and the other side of the document is also read, the document transported to the reversing unit is directed to the transport path. Or when the other side has already been read, the reversing roller for switching back toward the discharge tray without passing through the transport path and the document switched back toward the discharge tray without passing through the transport path are transported. A pre-discharge conveyance path, a conveyance roller configured to be rotatable in accordance with driving of the discharge roller, and conveying a document conveyed to the pre-discharge conveyance path toward the discharge roller, and a discharge roller When the reversing roller is provided in the driving means and rotates in the direction in which the document read by the reading unit is conveyed toward the reversing unit, the reversing roller is not transmitted to the discharge roller and the conveying roller. When the document transported to the reversing unit is rotated in the direction to switch back, the connecting means for transmitting a rotational force for sending the document transported to the transport path before discharge to the discharge tray to the discharge roller and the transport roller. It has.

According to the first aspect of the present invention, when the original is stacked on the original tray with one side thereof facing upward, the original is read by the reading unit and then sent to the discharge tray by the discharge roller. The documents on the discharge tray are stacked with one side facing down.
Here, when reading both one side and the other side of the document, first, when the reading unit reads one side conveyed from the document tray, this document is in a state where the front and back sides are reversed and the other side faces up. Is conveyed to the reversing roller, and is conveyed to the reversing portion by the rotation of the reversing roller.

  Next, when the reversing roller rotates in the opposite direction, the conveyance direction of the document is reversed, and the reading unit reads the other surface through the conveyance path from the reversing unit. If the sheets are discharged in this state, they are stacked on the discharge tray in the reverse order to the order in which they are set on the document tray.

  Therefore, the document is conveyed again to the reversing roller with one side facing up, and is conveyed to the reversing unit. The original on which both the one side and the other side are read is reversely reversed by the reversing roller, and is conveyed to the pre-discharge conveyance path that directly connects the reversing unit and the discharge tray. In this pre-discharge conveyance path, the front and back surfaces are reversed again, and one side is directed downward.

On the other hand, a transport roller is provided in the pre-discharge transport path, and the reversing roller and the transport roller are driven by rotation of a driving device that drives the discharge roller.
In other words, the reversing roller is simply driven by the driving device in spite of forward / reverse rotation, while the reversing roller rotates in the direction of transporting the document to the reversing unit, the discharge roller and the transporting roller function. In this case, it is not possible to call the subsequent document into the reverse tray unless the previous document is discharged to the discharge tray, and the period required for reading all the documents is long. turn into.

  However, the discharge roller driving means of the present invention is provided with connection means for transmitting rotation in only one direction, and reverse discharge control is performed. Specifically, when the reversing roller rotates in the direction in which the document is conveyed to the reversing unit, the connecting unit does not transmit the rotational force to the discharge roller and the conveying roller, whereas the reversing roller conveys to the reversing unit. When the printed document is rotated in the direction to switch back, the rotational force for sending the document transported to the transport path before discharge to the discharge tray can be transmitted to the discharge roller and the transport roller.

Therefore, the reversing roller can transport the subsequent document to the reversing unit in a state where the previous document is temporarily stopped on the transport path before discharge, and the distance between the documents can be shortened. Further, at the same time when the reverse roller conveys the subsequent document toward the conveyance path, the conveyance roller and the discharge roller can send the previous document to the discharge tray. As a result, the productivity related to document conveyance of the document feeder is improved.
Further, when the document once stopped can be sent out by both the discharge roller and the conveyance roller, the document can be stably conveyed.

According to a second aspect of the invention, in the configuration of the first aspect of the invention, when the reversing roller switches back the document conveyed to the reversing unit and discharges it to the discharge tray through the pre-discharge conveying path, the reversing roller reads the reading in the reading unit. It is characterized by rotating at the maximum speed.
According to the second invention, in addition to the action of the first invention, when the reverse roller conveys the original conveyed to the reversing section toward the discharge tray, the reverse roller reads the original with several kinds of reading speeds. Since the document is rotated at the maximum set speed and sent to the discharge tray, the discharge operation time required for discharging the document can be further shortened.

According to a third aspect, in the configuration of the first aspect, when the reverse roller is switched back and transported toward the transport path by the reverse roller, the reverse roller has the highest reading speed in the reading portion. Rotate by value.
According to the third aspect of the invention, in addition to the action of the first aspect of the invention, the reversing roller conveys several originals when the reversing roller conveys the original conveyed to the reversing portion toward the conveying path. Since it rotates at the maximum value of the set speed among the speeds and transports it to the transport path, it is possible to further shorten the period required to switch back the document.

  According to a fourth aspect of the invention, in the configuration of the first aspect of the invention, a reading side roller capable of transporting the read original toward the reversing roller or the discharge roller is provided in the vicinity of the reading unit, and the original is plain paper. If the paper is special paper with a different thickness, even when the other side has already been scanned, the document transported to the reversing part is switched back through the transport path without passing through the pre-discharge transport path, The sheet is conveyed from the reading unit toward the discharge roller without passing through the reversing unit.

According to the fourth invention, in addition to the operation of the first invention, the reading-side roller can convey the document read by the reading unit toward the reverse roller or the discharge roller. When the paper is a special paper having a thickness different from that of the paper, the reverse discharge path avoidance control is applied.
Specifically, even when the other side of this special paper has already been read, the document conveyed to the reversing unit is switched back toward the conveyance path, and the conveyance path before discharge, as in the case of reading the other side for the first time. Do not go to. Then, the reading-side roller conveys the document directly toward the discharge roller with one side of the document facing the discharge tray. Therefore, it is possible to reduce the load acting on the special paper and prevent jamming of the original in the pre-discharge conveyance path as compared with the case where the special paper is conveyed to the pre-discharge conveyance path where the curvature can be reduced. .

A fifth invention is an image forming apparatus equipped with any one of the first to fourth document feeders.
According to the fifth invention, in addition to the operations of the first to fourth inventions, the distance between the originals is shortened, so that the work period required for the image forming apparatus can be shortened and the reliability of the image forming apparatus can be reduced. Also improves.

  According to the present invention, since the distance between the preceding document and the succeeding document is shortened, it is possible to provide a document feeding device and an image forming apparatus equipped with the document feeding device in which productivity relating to document transportation is improved.

1 is a cross-sectional front view of a multifunction machine equipped with a document feeder of a first embodiment. FIG. 2 is a perspective view of the document feeder in FIG. 1. FIG. 3 is a cross-sectional front view of the document feeder of FIG. 2. FIG. 3 is a control block diagram of the document feeder in FIG. 2. It is explanatory drawing of the discharge side roller of FIG. It is explanatory drawing of the discharge side roller of FIG. FIG. 2 is an explanatory diagram of document conveyance by the document feeder of FIG. 1. FIG. 2 is an explanatory diagram of document conveyance by the document feeder of FIG. 1. FIG. 2 is an explanatory diagram of document conveyance by the document feeder of FIG. 1. It is explanatory drawing of the document conveyance by the document feeder of 2nd Example. It is explanatory drawing of the document conveyance by the document feeder of 2nd Example. It is explanatory drawing of the document conveyance by the document feeder of 3rd Example. It is explanatory drawing of the document conveyance by the document feeder of 3rd Example. It is explanatory drawing of the document conveyance by the document feeder of 3rd Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross section viewed from the front side of a multifunction machine 1 which is an example of an image forming apparatus.
The multifunction machine 1 of this embodiment has an in-body discharge-type apparatus main body 2, and a discharge tray 14 is formed below the reading unit 7.

  An original feeding device 20 is mounted on the upper side of the apparatus main body 2, more specifically, on the upper side of the reading unit 7, and the original feeding device 20 is configured to be able to automatically convey the original to a predetermined image reading position (ADF: Auto Document Feeder). Specifically, when the multifunction device 1 is used as a copying machine, a facsimile, or a network scanner, a document is transported from the document feeder 20 and its image surface is optically read by the reading unit 7.

  On the other hand, a front loading type paper supply device is disposed at the lower part of the apparatus main body 2. Specifically, the supply device according to the present exemplary embodiment includes two upper and lower sheet feed cassettes 3 along the height direction of the apparatus main body 2. Each cassette 3 is configured to be detachable from the apparatus main body 2. When the cassette 3 is pulled out toward the front side of the multifunction device 1, the inside of the cassette 3 is opened to the outside. When pushed toward the back side, the inside is closed.

In addition, arrows indicated by solid lines in the same figure represent a sheet conveyance path and its conveyance direction.
Various cassettes P before image formation are accommodated in each cassette 3 in a stacked state, and the sheets P are separated one by one from the cassette 3 and sent out in the left direction in the figure. The paper P in the transport path 4 is transported upward along the left side surface of the apparatus main body 2.

In addition, an openable manual feed tray 5 is provided on the right side surface of the apparatus main body 2, and the sheet fed from the tray 5 is also transported to the transport path 6 and then transported upward.
Inside the apparatus main body 2, a registration roller, an image forming unit 9, and a transfer unit 10 are sequentially arranged on the downstream side when viewed in the sheet conveyance direction. An exposure unit 8 and a toner container 11 are provided on the right side of the image forming unit 9, and laser light L is irradiated from the exposure unit 8 toward the photosensitive drum of the image forming unit 9. The toner is developed.

A fixing unit 12 and a discharge branching unit 13 are sequentially arranged on the downstream side of the transfer unit 10 when viewed in the paper conveyance direction, and a duplex printing unit 16 is arranged on the left side of the conveyance path 4. The duplex printing unit 16 includes a reverse conveyance path having one end connected to the downstream side of the fixing unit 12 in the conveyance path 4 and the other end connected to the upstream side of the image forming unit 9. In the case of single-sided printing, the paper discharged from the fixing unit 12 is discharged to the paper discharge tray 14 via the discharge roller 15.
On the other hand, in the case of double-sided printing, the paper is once sent toward the paper discharge tray 14 and then switched back and conveyed toward the reverse conveyance path of the double-sided printing unit 16 by reverse driving of the discharge roller 15. The image is returned to the upstream side of the image forming unit 9 in the path 4 and sent again toward the image forming unit 9.

Here, the document feeder 20 described above has a feeder main body 21 that can transport a document placed on the right side of FIG. 1 to the left and discharge it again to the right.
Specifically, as shown in FIG. 2, the feeder main body 21 has a document tray 22 that extends obliquely upward to the right from the central portion, and the document tray 22 is located at the central portion. Thus, the document is read on the reading position 39 and set on the tray 22.

The document tray 22 is provided with a width alignment guide 28, and the width alignment guide 28 is configured to be movable in the document width direction. When the width alignment guide 28 comes into contact with the side end portion of the document set on the document tray 22, the document setting position is determined.
The feeder main body 21 includes a paper feed cover 25 on the left side of the document tray 22 (FIGS. 2 and 3).

  The paper feed cover 25 is rotatably supported by the feeder main body 21 at the left end in the figure, and can open and close a document transport path disposed inside the paper feed cover 25 with respect to the outside. That is, the paper feed cover 25 in the state shown in the figure has the conveyance path closed, and the outer surface of the paper feed cover 25 corresponds to the top surface of the document feeder 20, while the inner surface of the paper feed cover 25 is conveyed. It functions as a road guide.

Here, when the paper feed cover 25 is rotated counterclockwise as viewed in FIGS. 2 and 3, the above-described transport path is opened, and various rollers disposed around the transport path can be seen. it can.
More specifically, a pickup roller 30, a separation roller pair 33, and a registration roller (adjustment unit) 35 are sequentially arranged in this conveyance path when viewed in the document conveyance direction from the document tray 22 (FIG. 3).

The pickup roller 30 is installed on the paper feed cover 25, contacts a document located on the uppermost layer of the document tray 22, and sends the document toward the separation roller pair 33. Whether or not the document is conveyed and the orientation of the document can be detected by a set switch or the like installed on the paper feed cover 25.
The separation roller pair 33 is provided on each of the paper feed cover 25 and the feeding apparatus main body 21, and feeds the document one by one toward the registration roller 35.

The registration roller 35 forms a nip with the opposing roller and feeds the document to the reading position 39 at the adjusted predetermined timing while correcting the oblique feeding of the document.
Further, a reading guide 38 is disposed on the downstream side of the registration roller 35 when viewed in the document conveying direction, and faces the contact glass of the reading unit 7. Specifically, this contact glass is composed of a wide document placing glass and a long and narrow document automatic reading glass located on the left side of the document placing glass in FIG.

More specifically, the document feeder 20 of the present embodiment also functions as a document presser, and the feeder main body 21 is rotatably supported by the apparatus main body 2 on the back side of the multifunction machine 1. The apparatus main body 21 can be opened and closed with respect to the reading unit 7.
Then, a resin-made pressing plate is provided on the lower surface of the feeding device main body 21, and the former document placement glass faces the pressing plate. When the original placed on the glass is pressed with a pressing plate and a predetermined button is pressed down, the image surface of the original can be read by a CCD via a mirror, a lens or the like disposed in the reading unit 7.

On the other hand, the latter glass for automatic reading of the document faces the reading guide 38 at the reading position 39 in FIG.
Specifically, a reading-side roller 36 is installed in the feeding apparatus main body 21 on the upstream side of the reading guide 38 when viewed in the document conveying direction, and a nip is formed with the opposing rollers so that the document faces the reading guide 38. Transport. When the document passes between the reading guide 38 and the automatic document reading glass, the image surface of the document is read.

  A reading side roller 37 and a path switching unit 40 are installed on the downstream side of the reading guide 38. The path switching unit 40 can switch between a conveyance path from the reading position 39 toward the reversing tray (reversing section) 23 and a conveyance path from the reading position 39 toward the discharge tray 24, and the reading-side roller 37 faces each other. A nip is formed with the roller, and the document is conveyed toward the reverse tray 23 and the discharge tray 24 according to the position of the path switching unit 40.

Here, when the conveyance path directly from the reading position 39 to the discharge tray 24 is selected by the path switching unit 40, the discharge roller 42 is disposed on the downstream side of the reading roller 37 when viewed in the document conveyance direction. The discharge tray 24 is arranged in this order.
The discharge roller 42 forms a nip with the opposing roller, and sends the document read at the reading position 39 to the discharge tray 24.

As shown in FIG. 3, the discharge tray 24 is positioned below the discharge roller 42 in the vicinity of the discharge roller 42, and has a shape inclined upward along the discharge direction. Can be laminated in the thickness direction.
On the other hand, when the conveyance path from the reading position 39 toward the reversing tray 23 is selected by the path switching unit 40, the reversing roller 44, The reversing trays 23 are arranged in this order.

The reverse tray 23 of this embodiment is used when both the front surface (one surface) and the back surface (other surface) of the document are read at the reading position 39.
Specifically, the reverse tray 23 is disposed between the document tray 22 and the discharge tray 24, and extends in the discharge direction like the document tray 22, and places a document between the document tray 22. It has a space where it can be placed.

The reversing roller 44 is provided in the vicinity of the discharge roller 42 and has a function of conveying the document from the reading side roller 37 toward the reversing tray 23, and the direction in which the document on the reversing tray 23 is conveyed. It has a function of conveying in the reverse direction.
More specifically, the reversing roller 44 of the present embodiment forms a nip with a reversing roller 45 (driven roller) opposed to the reversing roller 45, and the reversing roller 45 is reversed with excitation to the solenoid. When the solenoid is demagnetized while being separated from the roller 44, it can be brought into contact with the reversing roller 44 by the biasing force of the spring 46.

  When the reversing roller 44 rotates clockwise as viewed in FIG. 3, the document read at the reading position 39 can be conveyed to the reversing tray 23. On the other hand, when the reversing roller 44 rotates counterclockwise, the conveyance direction of the document conveyed to the reversing tray 23 is reversed, and the document on the reversing tray 23 is directed toward the registration roller 35 or switchback conveyance. It can be transported toward a path (pre-discharge transport path) 47.

  As described above, there are two paths in the direction in which the document is switched back. These paths are the path switching unit 41 located on the left side of the reversing roller 44 as viewed in the figure, and the switching units 40, 41. Is selected by another path switching unit 43 located between the two. The path switching unit 41 is biased downward by its own weight, and the path switching unit 43 is biased counterclockwise.

  Then, if it is necessary to read the front side and the original conveyed to the reversing tray 23 with the front side facing down, and then to read the back side, the rear end of the original viewed in the conveying direction is It stops between the path switching unit 41 and the reverse roller 44 and switches back toward the registration roller 35 with the rear end as the head. That is, the conveyance path from the reverse tray 23 toward the registration roller 35 is selected, and the reverse roller 44 cooperates with the reverse roller 45 so that the original on the reverse tray 23 faces the registration roller 35 with the back side facing up. Transport.

  On the other hand, when the back side is also read at the reading position 39 thereafter, the document is conveyed to the reversing tray 23 with the back side facing down. In this case, the rear end of the document viewed in the transport direction stops between the path switching unit 43 and the path switching unit 41, and the back end is used as the head to switch back toward the switchback transport path 47. . That is, the conveyance path from the reverse tray 23 toward the registration roller 35 is not selected, the conveyance path from the reverse tray 23 toward the switchback conveyance path 47 is selected, and the reverse roller 44 cooperates with the reverse roller 45 to reverse the reverse tray 23. Is conveyed toward the switchback conveyance path 47.

  The switchback conveyance path 47 of this embodiment communicates the conveyance path from the reading position 39 to the reversing tray 23 and the conveyance path from the reading position 39 to the discharge tray 24. It is formed in a substantially C shape having a small curvature as compared with a greatly curved path that reaches the discharge tray 24 directly via the roller 35 and the reading position 39.

The switchback conveyance path 47 is provided with a conveyance roller 48, and a nip is formed by the opposing rollers, and the document conveyed to the switchback conveyance path 47 is discharged with the surface facing downward. Transport toward 42.
Here, the various rollers 30, 33, 35 to 37, 42, 44, 48 described above are controlled by a controller (control means) 80 in the feeder main body 21 (FIG. 4).

  As shown in the figure, the controller 80 of this embodiment includes a path control unit 82, a motor control unit 84, a timing control unit 86, and a solenoid control unit 88. A predetermined program is executed based on the selection of the reading mode set by the input. More specifically, the path control unit 82 outputs a drive signal to the above-described path switching unit 40 to determine a document transport path.

The motor control unit 84 outputs drive signals to the motors that drive the various rollers 30, 33, 35 to 37, 42, 44, and 48. The timing control unit 86 adjusts the document feed timing and the like. The solenoid control unit 88 controls excitation and demagnetization of the solenoid in order to bring the reversing roller 45 into and out of contact with the reversing roller 44.
Note that the controller 80 includes, for example, a sensor 90 that can detect the type (especially thickness) of the document installed in the vicinity of the pickup roller 30, and a sensor 91 that can detect the width of the document from the position of the width alignment guide 28, for example. The signal from is also input.

Incidentally, the rollers provided on the discharge side of this embodiment, that is, the discharge roller 42, the reverse roller 44, and the transport roller 48 are driven by one reverse motor (drive device) 51 as shown in FIG. .
Specifically, based on the drive signal from the motor controller 84, the reverse motor 51 drives the drive pulley (drive means) 50 of the discharge roller 42 via the gear and belt, and the motor 51 rotates clockwise in FIG. When rotating, the driving pulley 50 also rotates clockwise. On the other hand, the rotation shaft 54 of the reversing roller 44 is configured to be rotatable in the direction opposite to the rotation direction of the drive pulley 50 via the belt, and when the drive pulley 50 rotates clockwise, the rotation shaft 54 is rotated. Rotates counterclockwise, the reversing roller 44 also rotates counterclockwise.

  The drive pulley 50 is provided on one end side of the rotation shaft 52 of the discharge roller 42, and a gear for rotating the conveyance roller 48 is provided on the other end side of the rotation shaft 52, and the conveyance roller 48 is interposed via the gear and the belt. When the drive pulley 50 rotates clockwise, the rotation shaft 58 rotates counterclockwise and the conveying roller 48 also rotates counterclockwise.

As described above, the reversing roller 44 is driven in accordance with the driving of the reversing motor 51 that drives the discharge roller 42, but the driving pulley 50 provided on the discharging roller 42 that drives the conveying roller 48 has a one-way clutch (connection means). Is provided.
The one-way clutch of this embodiment is provided on the inner peripheral side of the drive pulley 50.

For example, when the reverse motor 51 is rotated clockwise, the reverse roller 44 rotates counterclockwise. The rotating shaft 52 rotates clockwise, the discharge roller 42 rotates clockwise, and the transport roller 48 rotates counterclockwise (FIG. 5).
On the other hand, when the reverse motor 51 is rotated counterclockwise, the reverse roller 44 rotates clockwise (FIG. 6), but the rotational force of the pulley 50 is not transmitted to the rotary shaft 52. Thereby, the discharge roller 42 and the conveyance roller 48 do not rotate.

  In the document feeder 20 described above, when both the front and back sides of a document are read, first, for example, a plain paper document is set on the document tray 22 with the front side facing up, and a predetermined button is pressed. The uppermost document is conveyed toward the reading position 39 via the registration roller 35. Next, the document whose surface is read at the reading position 39 is directed to the reversing tray 23 with the surface facing down based on a signal from the path control unit 82.

At this time, the solenoid is demagnetized and a nip is formed by the urging force of the spring 46. When the original reaches the reverse roller 44 and the reverse roller 44 rotates clockwise, the original is placed on the reverse tray 23. Be transported.
The document conveyed to the reversing tray 23 changes its conveying direction due to the counterclockwise rotation of the reversing roller 44, travels toward the registration roller 35, and reaches the reading side roller 36 with its back surface facing downward. The document corresponds to the previous document P1 shown in FIG. At the same time, based on the signal from the timing control unit 86, the subsequent document P2 is fed and reaches the separation roller pair 33 with the surface thereof facing up.

  Subsequently, as shown in FIG. 7B, the original document P <b> 1 whose rear surface is also read is conveyed again from the reading side roller 37 toward the reverse roller 44. At the same time, the subsequent original P2 passes through the registration roller 35 and reaches the reading side roller 36 with its surface facing downward.

  Next, when the reversing roller 44 rotates clockwise, the previous document P1 is conveyed to the reversing tray 23 while being held in the nip with the reversing roller 45 and with the back surface facing downward (FIG. 8A). ). At the same time, the surface of the subsequent document P2 is read and directed to the reading side roller 37.

  Next, the reverse roller 44 rotates counterclockwise, and the previous document P1 begins to be transported to the switchback transport path 47 with the surface facing downward, and the leading end of the document P1 is viewed in the transport direction. When the rear end passes through the nip between the reverse roller 44 and the reverse roller 45, the solenoid is excited and the nip between the reverse roller 44 and the reverse roller 45 is released against the biasing force of the spring 46. (FIG. 8B). Thereafter, the leading edge of the original document P1 is directed to the discharge roller 42 by the conveying roller 48 while the reversing roller 44 rotates counterclockwise. At the same time, the subsequent document P2 is directed from the reading roller 37 to the reversing roller 44 with its surface facing downward.

  Thereafter, as shown in FIG. 9A, when the reversing roller 44 rotates clockwise, the subsequent document P2 is held in the nip with the reversing roller 45 and the reversing tray 23 with the surface facing downward. While the reversing roller 44 rotates clockwise, the discharge roller 42 and the conveyance roller 48 are stopped by the one-way clutch, and the original document P1 is temporarily stopped on the switchback conveyance path 47. Will do.

  When the reverse roller 44 rotates counterclockwise, the conveying roller 48 rotates counterclockwise via the one-way clutch, and the discharge roller 42 rotates clockwise. As shown in FIG. 9B, The subsequent document P2 faces the registration roller 35 with its back surface facing up, and at the same time, the previous document P1 has its surface facing down, that is, the image surface read first is facing down. It is sent to the discharge tray 24 in a state of facing.

The rotational speeds of the rollers 42, 44, 48 in the state shown in FIG. 9B are rotated by the motor control unit 84 at the maximum value of the set speed among the various reading speeds in the reading unit 7. Is set to
Further, when the subsequent document P2 reaches the reading roller 36 with its back surface facing downward, the subsequent document is fed and reaches the separation roller pair 33 with its front surface facing upward. It will be.

  Returning to FIG. 1 again, in the multi-function device 1 equipped with the document feeding device 20, the sheets are separated and sent one by one from the cassette 3 and the tray 5, and the sheets reach the registration rollers in the apparatus main body 2. This registration roller feeds the paper to the transfer unit 10 while correcting the oblique feeding of the paper and timing the toner image formed by the image forming unit 9.

Further, based on the image data read by the reading unit 7, irradiation of the laser beam L by the exposure unit 8 is controlled in the multifunction machine 1. As a result, an electrostatic latent image of the document image is created on the drum in the image forming unit 9, and then a toner image is formed on the drum from the latent image using the toner in the toner container 11 and transferred to a sheet. .
Thereafter, the sheet is fed toward the fixing unit 12 with an unfixed toner image carried thereon, and the toner image is fixed. Next, the paper discharged from the fixing unit 12 is discharged to the paper discharge tray 14 through the discharge branching unit 13.

  In the case of performing double-sided printing on this single-sided printing, the paper discharged from the fixing unit 12 is switched back to the double-sided printing unit 16 side immediately before being discharged to the paper discharge tray 14, and this paper is transported along the transport path. 4 is sent to the transfer unit 10 again. In this case, the toner image is transferred to the surface of the paper that has not been printed.

By the way, all of the above-mentioned documents are conveyed to the discharge tray 24 after being conveyed to the switchback conveyance path 47. However, even when reading both the front and back sides of the document, the conveyance path 47 can be avoided. good.
Specifically, in the example shown in FIGS. 10 and 11, the document is composed of special paper (for example, thick paper or thin paper) having a thickness different from that of plain paper, and the thickness is identified by the sensor 90. Alternatively, when selected on the panel of the apparatus main body 2, the path control unit 82 outputs a signal not to be transported to the switchback transport path 47.

More specifically, the document is set on the document tray 22 with its surface facing upward, and the uppermost document is conveyed toward the reading position 39 via the registration roller 35. Next, the document whose surface is read at the reading position 39 is directed to the reversing tray 23 with the surface facing downward.
At this time, the solenoid does not operate, and the nip is still formed by the urging force of the spring 46. When the original reaches the reverse roller 44 and the reverse roller 44 rotates clockwise, the original is reversed. It is conveyed to the tray 23.

  The original is changed in the conveying direction by the counterclockwise rotation of the reversing roller 44, and reaches the reading roller 36 toward the registration roller 35 with its back surface facing upward. The document whose back side is read at the reading position 39 is directed to the reversing tray 23 with the back side facing down. When this document reaches the reversing roller 44, the reversing roller 44 rotates clockwise, Is conveyed again to the reverse tray 23. The original corresponds to the original P3 shown in FIG.

Here, the document P3 is in a state where the back surface has already been read, but as shown in FIG. 10 (b), the registration is performed with the front surface facing up by the counterclockwise rotation of the reverse roller 44. It is directed toward the roller 35 and reaches the reading side roller 36.
Subsequently, in the present embodiment, since the surface of the original P3 is first read, the original P3 reaches the reading side roller 37 without being read by the reading unit 7 (color transport).

Next, the reading roller 37 conveys the document P3 toward the discharge roller 42 with the surface thereof facing downward (FIG. 11A), and the image surface read first is facing downward. It is sent to the discharge tray 24 (FIG. 11B).
In this example, after reading the front surface, the back surface is read and subsequent surface reading is prohibited. However, the first surface reading may be prohibited, the back surface may be read first, and then the front surface may be read. .

On the other hand, FIGS. 10 and 11 are examples in which the thickness of the document is taken into consideration, but in consideration of the width of the document, the examples in FIGS.
Specifically, when the sensor 91 identifies that the width of the document is narrower than the width of the A3 size paper or the A4 size paper, such as B5 size paper, or is selected on the panel of the apparatus body 2 In this case, the timing control unit 86 delays the sheet feeding timing by the pickup roller 30 and the registration roller 35, and the solenoid control unit 88 prohibits excitation of the solenoid.

This is because the rigidity (paper stiffness) of the B5 size document is lower than the rigidity of the A3 size or A4 size document, and can be strong enough to yield the conveying force of the reading side roller 37. In addition, the strength that can bend to the conveying force of the roller 37 is measured in advance by an experiment or the like.
Then, for example, a B5 size document is set on the document tray 22 with its surface facing up, and the uppermost document is conveyed toward the reading position 39 via the registration roller 35. Next, the document whose surface is read by the reading unit 7 goes to the reversing tray 23 with the surface facing downward.

  In this example, the solenoid is demagnetized even when the document is directed to the reversing tray 23, and a nip between the reversing roller 44 and the reversing roller 45 is formed by the urging force of the spring 46. continuing. When the document reaches the reversing roller 44, the reversing roller 44 rotates clockwise, and the document is conveyed to the reversing tray 23.

  This document changes its conveyance direction due to the counterclockwise rotation of the reversing roller 44, and reaches the reading roller 36 from the direction toward the registration roller 35 with its back surface facing upward. Then, the document whose back surface is read at the reading position 39 corresponds to the previous document P4 shown in FIG. 12A, and is directed to the reversing tray 23 by the reading side roller 37 with the back surface facing downward. At the same time, based on a signal from the timing control unit 86, a document P5 of the same size B5 is fed, and reaches the separation roller pair 33 with its surface facing up. It can be seen that the feeding timing of the subsequent document P5 is later than the feeding timing of the subsequent document P2 in FIG.

When the previous document P4 reaches the reversing roller 44, the reversing roller 44 rotates clockwise, and this document P4 is conveyed to the reversing tray 23 with the back side facing down (FIG. 12B). At the same time, the subsequent original P5 passes through the registration roller 35 and reaches the reading side roller 36 with its surface facing downward.
Next, the reversing roller 44 rotates counterclockwise, and the original document P4 is conveyed to the switchback conveying path 47 with the surface facing downward (FIG. 13A). At the same time, the surface of the subsequent document P5 is read and directed to the reading side roller 37.

In this example, even if the rear end of the original document P4 as viewed in the transport direction passes through the nip between the reverse roller 44 and the reverse roller 45, the solenoid is demagnetized, and the nip is still formed.
Further, as shown in FIG. 13B, when the rear end of the previous document P4 is also transported to the switchback transport path 47, the subsequent document P5 still begins to face the reversing tray 23 by the reading side roller 37. This is a stage, and the previous document P4 and the subsequent document P5 do not overlap.

  Thereafter, as shown in FIG. 14A, when the reversing roller 44 rotates clockwise, the subsequent document P5 is held in the nip with the reversing roller 45, and the reversing tray with its surface facing downwards. While the reversing roller 44 is rotating clockwise, the discharge roller 42 and the conveyance roller 48 are stopped, and the previous document P4 is temporarily stopped on the switchback conveyance path 47.

  When the reverse roller 44 rotates counterclockwise, the transport roller 48 rotates counterclockwise, and the discharge roller 42 rotates clockwise. As shown in FIG. Is directed to the registration roller 35 with its back side facing up, and at the same time, the previous document P4 is discharged with its front side facing down, that is, with the first scanned image side facing down. It is sent to the tray 24. Even if the trailing edge of the subsequent document P5 passes through the nip between the reverse roller 44 and the reverse roller 45, the nip remains formed.

Further, when the rear side of the original P5 is read at the reading position 39 and reaches the reading side roller 37 with the back side facing downward, the subsequent original is fed and the front side faces upward. In this state, the separation roller pair 33 is reached.
When these originals are not the B5 size described above but A3 or A4 size, the feed timing and solenoid control are the same as in the examples of FIGS.

As described above, according to the present embodiment, the documents are stacked on the document tray 22 with the surface thereof facing upward, and after being read at the reading position 39, the documents are sent to the discharge tray 24 by the discharge rollers 42. Is done. The documents on the discharge tray 24 are stacked with the surface thereof facing down.
Here, when both the front side and the back side of the original are read, first, when the reading unit 7 reads the front side conveyed from the original tray 22, the original is turned upside down with the back side facing up. Reaches the reversing roller 44. When the reverse roller 44 rotates, it is conveyed to the reverse tray 23.

  Next, when the reverse roller 44 rotates in the opposite direction, the document transport direction is reversed, and the reading unit 7 reads the back surface from the reverse tray 23 through the registration roller 35. As a result, the front and back surfaces are reversed again, but if they are left as they are, they are sent to the discharge tray 24 with the front side facing up, and are stacked on the tray 24 in the reverse order of the order set on the document tray 22.

  Therefore, the document is conveyed again to the reversing roller 44 with the front side facing up, and then conveyed to the reversing tray 23. The document on which both the front and back surfaces are read is transported to the switchback transport path 47 that directly connects the reversing tray 23 and the discharge tray 24 after the transport direction is reversed again by the reversing roller 44. In this conveyance path 47, the front and back are reversed again, and the surface is directed downward.

On the other hand, a transport roller 48 is provided in the transport path 47, and the reverse roller 44 and the transport roller 48 are driven by the rotation of a reverse motor 51 that drives the discharge roller 42.
In other words, the reversing roller 44 is simply driven by the reversing motor 51 in spite of forward / reverse rotation. While the reversing roller 44 is rotating in the direction in which the document is conveyed to the reversing tray 23, It becomes difficult for the transport roller 48 to perform its function. In this case, the subsequent original cannot be transported to the reverse tray 23 unless the previous original is discharged to the discharge tray 24, and all of them are also used. The period required to read the original is increased.

  However, the drive pulley 50 of the discharge roller 42 of this embodiment is provided with a one-way clutch, and reverse discharge control is performed by the motor control unit 84. Specifically, in the one-way clutch, when the reversing roller 44 rotates in the direction (clockwise) in which the document is conveyed to the reversing tray 23, the drive pulley 50 rotates counterclockwise, but the discharge roller 42 and the conveying roller 48 is stopped. On the other hand, when the reverse roller 44 rotates in the direction (counterclockwise) for switching back the document on the reverse tray 23, the drive pulley 50 rotates clockwise, the discharge roller 42 rotates clockwise, and The conveyance roller 48 rotates counterclockwise, and can transmit a rotational force that causes the document conveyed to the switchback conveyance path 47 to be sent to the discharge tray 24.

  Therefore, the reversing roller 44 can transport the document immediately after reading the surface to the reversing tray 23 with the previous document temporarily stopped on the switchback conveying path 47, and the distance between the documents can be shortened. it can. Further, at the same time when the reverse roller 44 conveys the subsequent original toward the registration roller 35, the conveying roller 48 and the discharge roller 42 can send the previous original to the discharge tray 24. As a result, the productivity related to document conveyance of the document feeder 20 is improved. Specifically, in the case of the apparatus 20 capable of transporting 50 sheets in one minute, about 3 to 4 sheets can be transported as compared with the conventional apparatus.

  In addition, the stopped discharge roller 42 and the transport roller 48 do not damage the document nipped by the roller, and the document temporarily stopped in the switchback transport path 47 can be sent out by both the discharge roller 42 and the transport roller 48. If so, the document can be stably conveyed.

  Further, when the reverse roller 44 conveys the subsequent document toward the registration roller 35, the conveyance roller 48 and the discharge roller 42 rotate the previous document at the maximum value of the set speed among the reading speeds to the discharge tray 24. Since the document is sent out, the discharge operation time required for the previous document can be further shortened. Further, the reversing roller 44 also rotates the subsequent document at the maximum setting speed of the reading speed and conveys it to the registration roller 35, so that the period required for the subsequent document switchback can be further shortened.

Further, the reading-side roller 37 can convey the document read at the reading position 39 toward the reversing roller 44 or the discharge roller 42, but this document is a special paper having a thickness different from that of plain paper (for example, In the case of thick paper or thin paper), reverse discharge route avoidance control by the route control unit 82 is applied.
Specifically, as shown in FIGS. 10 and 11, when the reverse roller 44 has already read the back side of this special paper, the document conveyed to the reverse tray 23 is read as in the case of reading the back side for the first time. Is switched back toward the registration roller 35 and is not directed toward the switchback conveyance path 47. The reading-side roller 37 conveys the document directly toward the discharge roller 42 with the surface thereof facing the discharge tray 24.

Therefore, compared with the case where the special paper is transported to the switchback transport path 47 where the load acting on the special paper can be reduced and the curvature can be reduced, the jamming of the original in the switchback transport path 47 is caused in advance. Therefore, the conveyance performance of the document feeder 20 is improved.
More specifically, the thick paper is easily slipped due to its strong stiffness, and the thin paper is easily caught due to its weak stiffness, but does not pass through the switchback conveyance path 47. Document jams can be reliably prevented.

  Further, the reversing roller 45 is configured so that a reversing roller 45 can be contacted and separated. The reversing roller 45 generates a nip by the biasing force of the spring 46 in accordance with the demagnetization of the solenoid. The roller 45 holds the document at the nip and conveys it to the reverse tray 23. Note that this nip can be released with the excitation of the solenoid.

  On the other hand, in order to shorten the distance between the originals, the solenoid described above is excited when the original document conveyed to the switchback conveying path 47 reaches the nip of the conveying roller 48, and the reversing roller 45 is moved from the reversing roller 44. The document is separated and easily accepts the subsequent document, but the document from the reversing roller 44 toward the conveyance roller 48 and the document from the reading side roller 37 toward the reversing roller 44 face each other. There are cases where they are transported and overlap. That is, the subsequent document is affected by the curved conveyance path from the reading side roller 37 to the reversing roller 44, and rubs in the direction of returning to the reading side roller 37 from the previous document. Load acts.

However, in this embodiment, driven roller separation control is applied to the reversing roller 44 as shown in FIGS.
Specifically, considering that the stiffness of the paper becomes weaker as the width of the subsequent document becomes narrower, only the reading side roller 37, that is, only the rear end of the subsequent document is held by the reading side roller 37 and reversed. If the document is conveyed toward the tray 23, the document is folded or waved, which causes a document jam (jam) in the conveyance path connecting the reading roller 37 and the reverse roller 44.

  In view of this, the solenoid control unit 88 according to the present embodiment is configured so that the width of the subsequent document is narrow (for example, B5 size paper) and the stiffness of the paper is strong enough to yield the conveying force of the reading side roller 37. The excitation of the solenoid described above is prohibited, and the subsequent document is conveyed while holding both the reading side roller 37 and the reverse roller 44, in other words, the leading end and the trailing end of the subsequent document. Further, the timing control unit 86 delays the sending time of the subsequent original so that it does not overlap with the previous original.

As a result, the distance between the originals is shortened, and the subsequent originals are stably conveyed. Therefore, the originals can be prevented from being jammed in the conveyance path connecting the reading side roller 37 and the reverse roller 44. Productivity related to conveyance of 20 originals is improved.
Further, if the excitation of the solenoid is prohibited, it is possible to suppress an increase in noise, power consumption and temperature in the apparatus due to the excitation as compared with the conventional case.

Further, when the subsequent original is wide (for example, A3 or A4 size paper), the distance between the originals can be easily shortened by separating the reverse roller 45 from the reverse roller 44.
Furthermore, since the distance between the originals is shortened, the work period required for the multifunction device 1 can be shortened, and the reliability of the multifunction device 1 is improved.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims.
For example, in the above-described embodiment, an example in which the image forming apparatus is embodied in a multifunction peripheral is shown. However, the present invention is naturally applicable to a copying machine, a printer, and the like having a document feeding device. Also in this case, as described above, there is an effect that the original can be stably conveyed while the distance between the originals is shortened.

1 MFP (image forming device)
7 Reading unit 20 Document feeder 22 Document tray 23 Reversing tray (reversing unit)
24 Discharge tray 35 Registration roller (adjustment unit)
36, 37 Reading side roller 42 Discharge roller 44 Reverse roller 45 Reverse roller (driven roller)
47 Switchback transport path (transport path before discharge)
48 Conveyance roller 50 Drive pulley (drive means)
51 Reverse motor (drive device)
80 controller (control means)

Claims (5)

A document feeding device that feeds a document conveyed from a document tray, reversed, and read by a reading unit to a discharge tray by a discharge roller,
A transport path for transporting a document from the document tray toward the reading unit;
A reversing unit for switching back a document read by the reading unit and changing a conveyance direction;
When configured to be rotatable in accordance with the driving of the driving device that drives the discharge roller, and transporting the document with one side read by the reading unit to the reversing unit, while reading the other side of the document, A reversing roller for switching back toward the discharge tray without passing through the conveying path when the original conveyed to the reversing unit is directed toward the conveying path or when the other side has already been read;
A pre-discharge conveyance path through which the document switched back toward the discharge tray without passing through the conveyance path is conveyed;
A transport roller configured to be rotatable in accordance with the driving of the discharge roller, and transporting a document transported to the transport path before discharge toward the discharge roller;
Provided in the discharge roller driving means, when the reversing roller rotates in a direction to convey the document read by the reading unit toward the reversing unit, the revolving roller rotates to the discharge roller and the conveying roller. When the reversing roller rotates in a direction to switch back the document conveyed to the reversing unit without transmitting force, the document conveyed to the pre-discharge conveyance path is transferred to the discharge roller and the conveyance roller. An original feeding apparatus comprising: a coupling means for transmitting a rotational force to be sent to the discharge tray. The document feeder according to claim 1,
When the reversing roller switches back the document conveyed to the reversing unit and discharges it to the discharge tray through the pre-discharge conveyance path, the reversing roller rotates at the maximum reading speed in the reading unit. A document feeder characterized by. The document feeder according to claim 1,
When the reversing roller switches back the document conveyed to the reversing unit and conveys the original toward the conveying path, the reversing roller rotates at the maximum reading speed in the reading unit. Document feeder. The document feeder according to claim 1,
In the vicinity of the reading unit, the reading unit further includes a reading side roller capable of conveying the read document toward the reversing roller or the discharge roller,
When the original is a special paper having a thickness different from that of plain paper,
Even when the other side has already been read, the document conveyed to the reversing unit is switched back through the conveyance path without passing through the conveyance path before discharge,
An original feeding apparatus that conveys the reading unit toward the discharge roller without passing through the reversing unit.   An image forming apparatus comprising the document feeder according to any one of claims 1 to 4.

Images