JPH0986807A - Automatic document conveyance device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document conveyance device which can be made compact and lightweight and reduce cost by shortening the conveyance path of double-sided document and making the structure thereof simple. SOLUTION: When a double-sided document is conveyed, a document whose obverse operation of the front side is finished is returned like a loop to a slit glass 2 through a switchback path 20 and a first conveyance passage 13 by making a pair of paper discharging rollers 18 communicate with the first conveyance passage 13 via the switchback path 20 when a changeover claw 21 is changed to the second communicating position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder mounted on an image forming apparatus, and more specifically, it separates documents from a plurality of document bundles one by one and conveys them to an image reading means stopped at a reading position. The present invention relates to an automatic document feeder.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, when a document bundle consisting of a plurality of documents is placed on a document table and a copy is instructed, the documents are separated and read one by one. Some automatic document feeders are configured to discharge a document to a predetermined discharge position when the document is read by the image reading unit that is transported to the position and stopped at the reading position. As a document feeder, for example, one described in Japanese Utility Model Laid-Open No. 3-85377 is known.

This is a document placing table on which a document consisting of a plurality of documents is placed, a separating and feeding means for separating and feeding the originals placed on the document placing table, and the separating and feeding means. Of the two slit glasses arranged along the downstream of the document transport direction, first and second transport drums respectively provided on the two slit glasses, and a document switch provided between the transport drums. There is provided a switchback means for backing and conveying to the second conveying drum, and an original discharge tray provided downstream of the second conveying drum in the conveying direction of the original.

In the automatic document feeder having such a structure, when a single-sided document is transported, the document separated by the separating / feeding means is transported to the second transport drum through the first transport drum and then to the second transport. After the image is read by the image reading means through the slit glass below the drum, it is discharged to the document discharge tray, and when the double-sided original is conveyed, the surface of the original separated by the separating and feeding means is passed through the slit glass below the first conveying drum. After the image is read by the image reading means, it is switched back by the switchback means to reverse the original surface, and then the rear surface of the original is read by the reading means through the slit glass below the second conveying drum, and then the original is discharged to the original discharge tray. It's designed for paper.

[0005]

However, such a conventional automatic document feeder is provided with two slit glasses and a feeding drum, and a switchback means provided between the slit glasses. Then, when the double-sided original is conveyed, after the front surface of the original is read through the slit glass below the first conveying drum, it is reversed by the switchback means, and then the rear surface of the original is read through the slit glass below the second conveying drum. As a result, the document conveying path is very long and the structure is complicated. For this reason, there is a problem that the automatic transporting device becomes large in size and heavy in weight, and the manufacturing cost increases.

Therefore, the invention according to claim 1 provides a low-cost automatic document feeder which can shorten the conveying path for double-sided originals and simplify the structure, thereby achieving a small size and a light weight. It is an object. According to the second aspect of the present invention, when the switchback path is short or when a long double-sided original is conveyed, the original can be prevented from being smeared due to the front and rear end sides of the original being rubbed, and the conveying load can be reduced. It is therefore an object of the present invention to provide an automatic document feeder that can stably convey a document and can improve reading accuracy.

[0007]

According to the first aspect of the present invention,
In order to solve the above problems, an automatic document feeder mounted on the top of an image forming apparatus having an image reading unit capable of reading a document by stopping at the reading position, while feeding the document to the reading position. In an automatic document feeder for reading an original by the image reading means, an original placing table on which a bundle of originals made up of a plurality of originals is placed, and the originals are separated from the original placing table one by one and separated. Separation / conveyance means that conveys the following document to the reading position through the first conveyance path that reverses and conveys the document, a driving member that is provided on the image forming apparatus side and can rotate in the forward and reverse directions, and a driven member that slides on the driving member. A member for discharging a document conveyed through the second conveyance path onto the document discharge tray after the reading is completed at the reading position, and a second side of the second conveyance path on the downstream side of the document conveyance direction. Connect predetermined locations on one transport path And a second communication position, which is provided on the upstream side of the paper discharge means in the document transport direction and which communicates the paper discharge means and the second transport path, and the second communication position which communicates the paper discharge means and the switchback passage. When the switching means is switched to the second communication position, the discharge means communicates with the first transport path via the switchback path.

In this case, when the switching means is switched to the second communicating position, the paper discharging means is communicated with the first conveying path through the switchback passage, so that when the double-sided original is conveyed,
When the back side of the document whose front side has been read is read, the document is returned to the reading position via the switchback passage and is conveyed in a loop. For this reason, the document transport path is shortened, and the structure thereof is simplified, so that the automatic document feeder is reduced in size and weight.
It will be cheap.

If the switchback path is short,
The document may be conveyed in order on the switchback path and the first and second conveyance paths in a state where the front end side and the rear end side of the document in the conveyance direction are sandwiched and overlapped by the sheet ejection unit. Since the driving member of the means is provided on the image forming apparatus side and the driven member is arranged at a position avoiding this position, the front end side of the document is always in sliding contact with the driving member side. As a result, the document is smoothly conveyed and discharged to the document discharge tray by the driving member. Further, even if the switchback path is short as described above, the original can be smoothly discharged, so that the original conveying path can be further shortened,
It is possible to further reduce the size and weight of the automatic document feeder.

In order to solve the above-mentioned problems, the invention according to claim 2 is characterized in that, in the invention according to claim 1, the driven member is provided so as to be able to come into contact with and separate from the drive member. In that case, when the front and rear ends of the original in the conveying direction are sandwiched by the sheet discharging means and overlap when the original is conveyed, if the driven member is separated from the driving member, the front and rear ends of the original are not rubbed and the original is not scraped. It doesn't get dirty.
Further, since the conveyance load is reduced, the conveyance speed of the document is stable, and the image reading accuracy is improved. The distance between the driving member and the driven member when separated from each other is preferably set to about 1 mm or more, which is a distance corresponding to the length of two originals.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views showing an embodiment of an automatic document feeder according to the invention described in claim 1 or 2, and show an example in which the automatic document feeder is attached to an image forming apparatus such as a copying machine. .

First, the configuration will be described. In FIGS. 1 and 2, reference numeral 1 denotes a copying machine as an image forming apparatus, and a slit glass (reading position) 2 and a contact glass 3 are provided on the upper surface of the copying machine 1. This slit glass 2
An exposure lamp 4 as an image reading means, a first mirror 5 and the like are provided below the contact glass 3 and the lamp 4 and the first mirror 5 when reading an original placed on the contact glass 3. Moves under the contact glass 3 in the left-right direction in FIG. 1, and when reading a document on the slit glass 2, it stops below the slit glass 2 and exposes the document surface by the exposure lamp 4, As is known, this reflected light is imaged on the CCD through the first mirror 5 and a lens (not shown).

An automatic document feeder (hereinafter, simply referred to as ADF) 6 is mounted on the upper portion of the copying machine 1, and the document placed on the contact glass 3 is placed on the contact glass 3 on the lower surface of the ADF 6. A reflecting plate 7 is provided which is pressed and serves as a white reference when reading a document. Also,
A document placing table 8 is provided on the upper part of the ADF 6, and a document bundle P made up of a plurality of documents is placed on the placing table 8. The original stack P placed on the original placing table 8 can be brought into contact with and separated from the original stack P by a calling roller 9
After being fed by the separation roller pair 10, they are separated by the separation roller pair 10. The pair of separation rollers 10 are both designed to rotate in the clockwise direction so as to separate the uppermost document from the document stack P.

This separated original is a pullout roller pair 11
Further, the pair of conveying rollers 12 conveys the original along the first conveying path 13, and the first conveying path 13 constitutes a conveying path for reversing the original and conveying it to the slit glass 2. In the present embodiment, the calling roller 9 and the separation roller pair described above are used.
10, the pull-out roller pair 11 and the transport roller pair 12 constitute a separating / transporting means, and are driven by the sheet feeding motor 51. Further, the roller 10a on the lower side of the separation roller pair 10 is connected to a paper feed clutch 55, and this paper feed clutch 55 is driven based on a signal from the controller 50, and when the preceding document is separated, The roller 10a is designed to rotate around the separated document without transmitting the driving force of the sheet feeding motor 51.

A document setting sensor 14 is provided on the document placing table 8, and the sensor 14 detects the presence or absence of a document on the document placing table 8 and outputs a signal to the controller 50. There is. Further, a document separation sensor 15 is provided between the separation roller pair 10 and the pullout roller pair 11, and this sensor 15 detects that the documents are separated and outputs a signal to the controller 50. When this signal is input, the controller 50 controls the sheet feeding clutch 55 as described above so that the driving force of the sheet feeding motor 51 is not transmitted to the rollers 10a.

A transport roller pair 16 is provided downstream of the slit glass 2 in the document transport direction.
16 is driven by the paper feed motor 51, and the slit glass 2
The document whose reading has been completed is conveyed to the pair of paper discharge rollers (paper discharge means) 18 through the second conveying path 17. The paper discharge roller pair 18 is composed of a driving roller (driving member) 18a and a driven roller (driven member) 18b. The driving roller 18a is disposed on the copying machine 1 side and is rotated in the forward and reverse directions by a paper discharging motor 53. It has become so.

Then, the pair of paper discharge rollers 18 sandwich the original document which has been read on the slit glass 2 and place it on the original table 8.
The document is discharged onto a document discharge table 19 provided at the bottom. Further, the driven roller 18b is configured to be contacted and separated from the driving roller 18a by the solenoid 52. When the driven roller 18b is separated from the driving roller 18a, the driven roller 18b is separated from the driving roller 18a by about 1 mm as shown in FIG. The above gap (corresponding to the thickness of about two originals) is formed. Further, the solenoid 52 is driven by a signal from the controller 50.

On the other hand, on the downstream side of the sheet discharge roller pair 18 in the document transport direction, the second transport path 17 is located on the downstream side of the document transport direction and the first transport path 13.
Is provided with a switchback passage 20 communicating with a predetermined portion of the above, and a switching claw 21 as switching means is provided on the upstream side of the paper discharge roller pair 18 in the document conveying direction. The switching claw 21 is in a first communication position (shown by a solid line in FIG. 1) where the switching roller 54 controlled by the controller 50 communicates the paper discharging roller pair 18 and the second conveying path 17, and the paper discharging roller pair 18 and the switch. It can be switched to a second communication position (shown by a broken line in FIG. 1) that communicates with the back passage 20, and the conveyance path of the document can be changed.

A registration sensor is provided on the first transport path 13.
22 is provided, and this sensor 22 detects the front end portion of the document and outputs a signal to the controller 50. Further, a paper discharge sensor 23 is provided on the upstream side of the paper discharge roller pair 18 in the direction in which the document is conveyed.
Detects the front and rear edges of the document and outputs a signal to the controller 50.

The controller 50 drives the paper feed motor 51 and the paper feed clutch 55 based on the document set sensor 14 and the document separation sensor 15, and also the registration sensor.
The solenoid 52, the paper discharge motor 53, and the switching solenoid 54 are controlled based on the detection signals from the paper discharge sensor 22 and the paper discharge sensor 23, as will be described later. In addition, in FIG. 1, 24
Is a scale for picking up the original that has passed through the slit and the glass 2 and carrying it to the second carrying path 17.

Next, the operation of conveying a double-sided original will be described. First, when a document stack P composed of a plurality of double-sided documents is placed on the document table 8, the document set sensor 14 detects that the documents are placed and outputs a signal to the controller 50. When the copy start switch provided on the operation panel of the copying machine 1 is pressed, the controller 50 causes the paper feed motor 51 to drive the separation / paper feed means in response to the operation signals of the set sensor 14 and the copy start switch.

That is, the original stack P is fed by the calling roller 9 which is in contact with the original stack P, and then the separation roller pair 10 is fed.
And then conveyed along the first conveying path 13 by the pull-out roller pair 11 and the conveying roller pair 12. When the front end of the original P1 is detected by the separation sensor 15, the paper feed clutch 55 prevents the roller 10a from idling and separating the succeeding original.

Next, when the front end of the original P1 is detected by the registration sensor 22, the controller 50 drives the exposure lamp 4 based on this signal to read the front surface of the original P1 and drive the paper discharge motor 53. The drive roller 18a is normally driven clockwise. Next, the read original P1 is conveyed by the conveying roller pair 16 toward the paper discharging roller pair 18 via the second conveying path 17, and at this time, the switching claw 21 is indicated by the solid line in FIG. Since the original P1 whose front surface has been read is located at the 1-communication position, the pair of conveying rollers 18
It is sandwiched between and conveyed (see FIG. 4).

Next, the rear end portion of the original P1 is the paper discharge sensor 2
3 is detected by the controller 50, the controller 50
After temporarily stopping the operation of 3, after switching the switching claw 21 to the second communication position shown by the one-dot chain line by the switching solenoid 54,
The paper discharge motor 53 is reversely driven in the counterclockwise direction. Therefore, the original P1 whose rear end is sandwiched by the pair of paper discharge rollers 18
Are transported to the first transport path 13 through the switchback path 20 (see FIG. 5).

At this time, when the front end of the original P1 is detected by the registration sensor 22, the controller 50 temporarily stops the operation of the paper feeding motor 51 and switches the switching solenoid 54 to the first communication position. Next, the paper feed motor 51
Drive to restart the conveyance of the original P1, and then the exposure lamp 4
Is driven to read the back side of the original P1 and the discharge motor 5
3 is driven and the original P1 is ejected by the ejection roller pair 18
Paper is ejected to 19. At this time, when the trailing edge of the discharged document P1 is detected by the discharge sensor 23, the paper feed clutch 55 is driven to feed the subsequent document.

On the other hand, when the switchback passage 20 is short or when a long original P1 such as A4 is conveyed, the front and rear ends of the original P1 may be sandwiched by the pair of discharge rollers 18 in a stacked state. is there. In the present embodiment, when the document P1 is conveyed in such a state, as shown in FIG. 5, the document P1 whose front surface has been read is conveyed to the first conveyance path 13 via the switchback passage 20 and registered. When the sensor 22 detects the front end of the document P1, the controller 50 drives the solenoid 52 to separate the driven roller 18b from the driving roller 18a by δ, and the operation of the sheet feeding motor 51 is temporarily stopped. The switching solenoid 54 is switched to the first communication position. Next, the paper feed motor 51 is driven to restart the conveyance of the original P1, and the exposure lamp 4 is driven to drive the original P.
The back surface of 1 is read, and the paper discharge motor 53 is driven to convey the document P1 by the paper discharge roller pair 18.

At this time, as shown in FIG. 6, the original P1 is conveyed in a state where the front and rear ends thereof are overlapped. Next, the original P
When the rear end of 1 is detected by the registration sensor 22, the controller 50 drives the solenoid 52 to drive the driven roller.
18b is brought into contact with the driving roller 18a through the original P1 to eject the original P1. In this embodiment, when conveyance of a long original P1 such as A4 is set on the operation panel of the copying machine 1, the driven roller 18b is driven by the driving roller 18a as described above.
It is also possible to perform control so as to separate the driven roller 18b from the driving roller 18a based on the sensor information by providing a sensor for detecting the length of the document on the document mounting table 8. When the switchback passage 20 is short, the control of separating the driven roller 18b from the driving roller 18a may be always performed.

As described above, in this embodiment, the switching claw 21 is set to the second
When switched to the communication position, the paper discharge roller pair 18 is communicated with the first transport path 13 via the switchback path 20, and when the duplex original is transported, the document whose front surface is completed is switched back to the switchback path 20 and the first transport path 13. Since the sheet is returned to the slit glass 2 through the sheet, the original can be conveyed in a loop. Therefore, it is possible to reduce the size and weight of the ADF 6 by shortening the document transport path and simplifying the structure thereof, and to manufacture the ADF 6 at low cost.

Further, the driving roller 18a is provided on the copying machine 1 side,
Since the driven roller 18b is arranged at a position avoiding this position, the front end side and the rear end side of the document in the conveyance direction are the discharge roller pair 18
When the document is conveyed in this order on the switchback passage 20, the first conveyance path 13 and the second conveyance path 17 in a state of being sandwiched by and overlapped with each other, the front end side of the document can be always brought into sliding contact with the driving roller 18a, The document can be smoothly conveyed and discharged to the document discharge table 19 by the driving roller 18a. Further, even if the switchback passage 20 is short, the original can be smoothly discharged, so that the original conveying path can be further shortened, and the ADF 6 can be made even smaller and lighter.

Further, since the driven roller 18b is provided so as to be able to contact with and separate from the driving roller 18a, and the gap δ between the driving roller 18a and the driven roller 18b is set to 1 mm when the driven roller 18a is separated, when the switchback passage 20 is short. When the front and rear ends of the original in the conveying direction are pinched and overlapped by the paper discharge roller pair 18 when a long original is conveyed, if the driven roller 18b is separated from the driven roller 18a, the front and rear edges of the original will be separated. Rubbing can be prevented, and the original can be prevented from becoming dirty.
Further, since the conveyance load can be reduced, the document conveyance speed can be stabilized and the image reading accuracy can be improved.

[0031]

According to the first aspect of the present invention, when a double-sided original is conveyed, the original is returned to the reading position via the switchback passage when the rear side of the original whose front side has been read is read. Can be conveyed in a loop. Therefore, it is possible to shorten the document transport path and simplify the structure. As a result, the automatic document feeder can be reduced in size and weight and can be manufactured at low cost.

When the switchback path is short,
The document may be conveyed in the order of the switchback path and the first and second conveyance paths in a state where the front end side and the rear end side of the document in the conveyance direction are sandwiched and overlapped by the sheet ejection means. Since the driving member is provided on the image forming apparatus side and the driven member is arranged at a position avoiding this position, the front end side of the document can always be brought into sliding contact with the driving member side.
As a result, the original can be smoothly conveyed and ejected to the original ejection tray by the drive member. Further, even if the switchback path is short as described above, the original can be discharged smoothly, so that the original conveying path can be further shortened, and the automatic original conveying apparatus can be made smaller and lighter. You can

According to the second aspect of the present invention, when the front and rear ends of the original in the conveying direction are pinched and overlapped by the sheet discharging means when the original is conveyed, the driven member is separated from the driving member. It is possible to prevent the front and rear end sides from being rubbed, and to prevent the document from getting dirty. Further, since the carrying load can be reduced, the carrying speed of the document can be stabilized, and the image reading accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an automatic document feeder according to the invention of claim 1 or 2. FIG.

FIG. 2 is a block diagram of a control system according to an embodiment.

FIG. 3 is a perspective view of a driven member of one embodiment abutting against a driving member.
It is a state when separated.

FIG. 4 is a diagram showing a state in which a trailing edge of a document is clamped and stopped by a sheet discharging unit according to an embodiment.

FIG. 5 is a diagram showing a state in which an original according to one embodiment is returned to the first transport path via the switchback path.

FIG. 6 is a diagram showing a state in which front and rear end sides of a document according to an embodiment are overlapped and pinched by a sheet discharging unit.

[Explanation of symbols]

 1 Copier (image forming apparatus) 2 Slit glass (reading position) 4 Exposure lamp (image reading means) 5 First mirror (image reading means) 6 ADF (automatic document feeder) 8 Document loading table 9 Calling roller (separation Conveyor means 10 Separation roller pair (separation / conveyance means) 11 Pullout roller pair (separation / conveyance means) 12 Conveyance roller pair (separation / conveyance means) 13 First conveyance path 17 Second conveyance path 18 Paper ejection roller pair (ejection Paper means) 18a Driving roller (driving member) 18b Followed roller (driven member) 19 Original paper ejection table 20 Switchback passage 21 Switching claw (switching means) P Original

Claims (2)

[Claims] 1. An automatic document feeder mounted on the top of an image forming apparatus having image reading means capable of reading a document by stopping at the reading position, wherein the image reading is performed while the document is being transported to the reading position. In an automatic document feeder configured to read a document by means of a document, a document table on which a document stack made up of a plurality of documents is placed, and one document is separated from the document table and the separated document is separated. A separating / conveying unit that conveys the sheet to the reading position through a first conveying path that reverses and conveys the sheet;
A driven member that is in sliding contact with the drive member, and discharges the document conveyed through the second conveyance path onto the document discharge tray after the reading is completed at the reading position; and the second conveyance path. A switchback passage that connects the downstream side of the document conveyance direction and a predetermined location of the first conveyance path, and a first communication position that is provided on the upstream side of the paper discharge means in the document conveyance direction and communicates the paper discharge means and the second conveyance path. And a switching means that can communicate with a second communication position that communicates the paper discharge means with the switchback passage; and when the switching means is switched to the second communication position, the paper discharge means carries out the first conveyance via the switchback passage. An automatic document feeder which communicates with a path. 2. The automatic document feeder according to claim 1, wherein the driven member is provided so as to come into contact with and be separated from the driving member.