JP2002226114A - Document feeder and image forming device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of dust from a roller reversing and conveying a document. SOLUTION: This document feeder comprises a conveying part for conveying and feeding the document to an image reading position for reading an image of the document, and a switch-back part having a pair of rollers 24a, 24b for temporarily conveying the document received from the conveying part to a downstream side of the image reading position, and then feeding the document to an upstream side of the conveying part by feeding the document in the reverse direction, and truncated conical run-off parts 24d are formed on both end parts of at least one of the rollers 24a to prevent the both ends of at least one of the rollers 24a from touching the document.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention allows a document to be sent to an image reading position for reading an image of the document, then the document is turned over and sent back to the image reading position, and both sides of the document can be read at the image reading position. The present invention relates to an image forming apparatus such as a copying machine or a printer which forms an image on a sheet based on image information read at an image reading position by providing the original feeding apparatus in the apparatus main body.

[0002]

2. Description of the Related Art Conventionally, a document feeder automatically feeds a document to an image reading position of an image reading device for reading the document. The image reading device is often provided on the upper part of the main body of the image forming apparatus.

[0003] The manuscript includes a manuscript in which characters, figures, pictures, and the like are described on a sheet, in addition to a manuscript in which sentences are described. Examples of the sheet include plain paper, cardboard, and a thin resin sheet which is a substitute for plain paper.

The image reading apparatus reads a document based on reflected light reflected by the light emitted from a light source fixed to the document conveyed on the contact glass. There is something.

[0005] In particular, when the image reading apparatus uses the continuous reading method, as shown in FIG.
The original is mounted on the apparatus main body 101 of the image forming apparatus, and conveys the document so as to pass over the upper surface of the contact glass 2 of the apparatus main body 101. The image reading device 33 mounted on the apparatus main body 101 irradiates light from a light source 3 such as a lamp onto the conveyed document through the contact glass 2 and reflects the reflected light on the mirror 4. C
An image of a document that has been photoelectrically converted by a CD or the like is read. That is, the upper surface of the contact glass 2
It is located at the image reading position of the image reading device 33 in the apparatus main body 1.

In the document feeder 100, after the image of the document is read by the image reading device 33 on the contact glass 2, the document is transferred to the pair of reverse transport rollers 1 by one.
02, switchback is performed on the document discharge tray 16 and the front and back sides of the document are reversed, and the contact glass 2 is returned again.
The document is conveyed upward and the image reading device reads the back side image of the document.

[0007]

However, in the conventional automatic document feeder, when the document is turned upside down, the document rubs against the pair of reversing conveyance rollers 102 so that dust such as shavings of the pair of reversing conveyance rollers 102 is generated. Occurs. The generated dust is carried to the contact glass 2 at the image reading position 9 while adhering to the document, and may stay at the image reading position 9. The retained dust is read by the document reading device 33 together with the image of the document. As a result, the staying dust forms a line (hereinafter, referred to as “black streak”) on the image of the document copied on the sheet by the image forming apparatus.
It appears as

Therefore, the conventional document feeder has a problem that a black streak is generated in the image of the document copied on the sheet by the image forming apparatus.

According to the present invention, there is provided a document feeder in which dust is not generated from a roller for reversing and transporting a document so that dust does not stay at an image reading position, and the document feeder is provided in a main body of the apparatus to form a sheet. It is an object of the present invention to provide an image forming apparatus capable of forming an image without generating black streaks.

[0010]

In order to achieve the above object, a document feeder according to the present invention comprises: a document feeder for feeding and feeding the document to an image reading position for reading an image of the document; Reversing and transporting means having a pair of rollers for receiving the document and temporarily transporting the document to the downstream side of the image reading position, and then reversely feeding the document to the upstream side of the document transporting means, A frusto-conical relief portion is formed at both ends of at least one of the rollers so that both ends of at least one of the rollers do not contact the original.

The document feeder according to the present invention further comprises:
A stiffening means for raising a part of the document conveyed by the pair of rollers is provided, and the relief portion is formed on the roller on which the document is raised.

According to the present invention, there is provided a document feeder comprising:
Two document feeders, image reading means for reading an image of a document sent by the document feeder, and image forming means for forming an image on a sheet based on image information of the document read by the image reading means, It has.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a document feeder according to an embodiment of the present invention and a copying machine provided with this device in a main body will be described with reference to the drawings.

The document feeder can be provided not only in a copying machine but also in a main body of an image forming apparatus such as a printer. Therefore, the equipment provided with the document feeder is not limited to the copying machine. Although the document feeder according to the present embodiment automatically supplies a plurality of documents continuously to the image reading position, the document can be supplied one by one by the user. ing. Therefore, the document feeder is not limited to the automatic document feeder.

(Copying Machine) FIG. 1 is a schematic front sectional view of a copying machine (image forming apparatus) 51.

At the top of the copying machine main body 1, there is provided a document feeder 10 for conveying a document to the contact glass 2 at the image reading position 9 and discharging the document. The CPU 31 provided in the main body 1 of the copying machine 51 uses the light source unit 52 including the light source 3 and the mirror 4 to optically reflect reflected light obtained by irradiating a document passing through the contact glass 2 with the mirror 4. Device (CCD or other device)
An image is recorded by projecting the image onto the photoconductor 53 and the photoconductor.

The photosensitive drum (image forming means) 54 includes
Light corresponding to the recorded document image is irradiated to form a latent image. The latent image becomes a toner image by toner supplied from a toner supply device (not shown). Cassette 5
Reference numeral 5 stores a recording medium (sheet) S such as paper or a plastic film.

The recording medium S is transferred from the cassette 55 to the photosensitive drum 54 and the transfer device 56 in response to a recording signal from the CPU 31.
Is supplied between The recording medium S is a photosensitive drum 54
Is transferred by the transfer device 56. Then, the recording medium onto which the toner image has been transferred is
6 to fix the toner image.

When images are formed on both sides of the recording medium, the recording medium on which the image on one side is fixed by the fixing device 57 is
After passing through a double-sided path 58 provided on the downstream side of the fixing unit 57, the sheet is turned upside down in the middle of the switchback conveyance path 32 and sent again between the photosensitive drum 54 and the transfer unit 56. As a result, the toner image is also transferred to the back surface of the recording medium. Finally, the toner image is fixed on the recording medium by the fixing device 57, and the recording medium is discharged to the outside.

The apparatus main body 1 also includes a contact glass 5 (see FIG. 2) having an area on which a document can be placed. The image reading unit 33 opens and closes the document feeder 10 and moves the document placed on the upper surface of the contact glass 5 by moving the light source unit 52 including the light source 3 and the mirror 4 in the sub-scanning direction. Glass 5
It is also possible to read the image of the document via the.

(Document Feeding Device) In FIGS. 2 and 3, a document feeding device 10 separates a document tray 15 on which a plurality of documents can be placed one from another and a document on the document tray 15 one by one. A feeding unit 11 for feeding the document toward the contact glass 2, a conveying unit 12 for passing the document along the upper surface of the contact glass 2, and a discharge unit 13 for receiving and discharging the document passed through the upper surface of the contact glass 2. And a document discharge tray 16 for storing a document that has been read from the discharge unit 13 after image reading is completed.

Further, the document feeder 10 also includes a switchback unit 14. The switchback unit (reverse transport unit) 14 switches the document discharged from the upper surface of the contact glass 2 by switchback transport in the discharge unit 13, turns over the original, and sends it back to the feeding unit 12.
Is turned over on the upper surface of the contact glass 2 so that the original can be conveyed. Here, the document tray 15 is inclined at a certain angle and is arranged above the document discharge tray 16 with a space secured.

The width of the original placed on the original tray 15 is regulated by a side guide 17 for regulating the side portion thereof, and the leading end thereof is regulated by contacting a stopper 60. The document tray 15 is rotatably provided on the main body 7 about a fulcrum 15a of the main body 7. For this reason, the original placed on the original tray 15 rotates around the leading end.

The feeding section 11 includes the separating section 8, a pair of registration rollers 21, and the like. The separating unit 8 is configured to lower the uppermost document on the document tray 15 and contact the uppermost document.
The document feed roller 19 includes a document feed roller 19 and a separation pad 20 that allow only the top document among the documents fed out and allow the second and subsequent documents to pass therethrough.
The registration roller pair 21 (registration drive roller 21a and registration driven roller 21b) once receives the leading edge of the separated document, regardless of whether the document is skewed,
If the document is skewed, the document is straightened straight and sent downstream.

The transport section 12 is provided on the upstream side of the contact glass 2 and supplies a document to the contact glass 2 with a pair of transport rollers 22 (transport drive roller 22a and transport driven roller 22b), a guide plate 26b, and contacts the document. Glass 2
Roller pair 23 (conveyance driving roller 23a, conveyance driven roller 23b), etc., which discharge paper to the downstream side. Documents are stored in the contact glass 2 and the pick-up guide 6 of the main body 1 and the backup guide 26 of the document feeder 10.
a and is conveyed along the conveyance path 26 formed by the above.

The discharge unit 13 and the switchback unit 14 share a part on the document discharge tray 16 side. Reverse transport roller pair 24 (reverse transport roller drive 24a, reverse transport driven roller 24b) for discharging a document to document discharge tray 16
As shown in FIG. 5, two sets are provided with the center in the width direction of the path through which the document passes. The reverse transport roller pair 24 includes a reverse transport drive roller 24a whose roller portion is formed of a rubber member, and a reverse transport driven roller 24b that can be brought into contact with and separated from the reverse transport drive roller 24a.

In the duplex mode, the reverse transport roller pair 24 reversely rotates with the rear end of the document sandwiched therebetween to switch back (reversely run) the document and send it to the discharge unit 13 as described later. As described above, the control is performed by the CPU 31. Further, the reverse transport roller pair 24 is configured such that the reverse transport driven roller 24b comes into contact with and separates from the reverse transport drive roller 24a.
When the leading and trailing edges of the document circulated from 4 through the discharge unit 13 and the transport unit 11 pass each other, they can be transported without any trouble.

A waist rib 61 shown in FIGS. 4 and 5 is provided in the vicinity of the outer end of the two pairs of reverse conveying rollers 24. The waist rib 61 protrudes at a height equal to or higher than the nip of the pair of reverse conveying rollers 24. The waist ribs 61 are used to raise a part of an original with a weak waist such as a thin paper to waist,
It is provided in order to prevent a discharge failure due to cramping of the document when the document is discharged.

The discharge unit 13 and the switchback unit 14
Is provided with a flapper 29 for guiding the document to the discharge unit 13. The flapper 29 is constantly urged toward the discharge section 13 (downward) by an urging spring (not shown). The flapper 29 is pushed up by the leading edge of the discharged document when the document is sent to the reverse transport roller pair 24 along the document discharge path 27 to allow the document to pass.

The flapper 29 is pulled downward by the urging spring to close the document discharge path 27 and guide the document to the switchback path 28 when the reverse conveyance roller pair 24 performs switchback conveyance of the document. It is supposed to. The document discharge path 27 is formed by a document discharge upper guide 27a extending a backup guide 26a provided opposite to the contact glass 2 and a document discharge lower guide 27b of a resin molded product integrated with the document discharge tray 16. ing.

The switchback path 28 is formed by a switchback lower guide 28b and a switchback upper guide 28a provided continuously on the document guide surface of the flapper 29, and guides the document to the nip of the registration roller pair 21. It has become.

The switchback path 28 and the document supply path 25 are formed so as to meet at the nip of the registration roller pair 21. Therefore, the document supply path 25 from the document supply roller 19 to the registration roller pair 21 and the flapper 2
Switchback path 2 from 9 to registration roller pair 21
8 is formed substantially linearly, guides the document smoothly to the registration roller pair 21 without applying stress to the document, and smoothly guides the front end of the document to the registration roller pair 21 to skew the document. It can be straightened straight.

Further, the registration roller pair 2 is located at the merging position.
A mylar 28c for guiding a document to the nip is extended. The mylar 28c reliably guides the original to the nip of the registration roller pair 21 irrespective of the original supplied through the original supply path 25 and the original supplied through the switchback path 28 and re-supplied. This ensures that the skew of the original can be corrected.

As shown in FIG. 3, the document supply path 25 has an upper guide plate 25a and a lower guide 25b opposed to each other. As shown in FIG. 7, the upper guide plate 25a is fixed to an outer cover 10a rotatably supported by a pivot 10c on the main body 7 of the document feeder 2.
When the outer cover 10a is rotated counterclockwise integrally with the upper guide plate 25a, the body 7 of the document feeder 2 can be opened with the document supply path 25 as a boundary. On the exterior cover 10a, a feeding roller 18, a document supply roller 19, and a driven roller 2 of a registration roller pair 21 are provided.
1b is provided so as to rotate integrally.

In FIG. 7, the upper switchback guide 28a is formed integrally with the lower guide 25b, and this integrated guide is supported by the rotating shaft 24c of the reverse transport drive roller 24a so as to be rotatable clockwise. Have been. In addition, by integrating the switchback upper guide 28a and the lower guide 25b, the separation pad 2
The biasing spring 20a of the zero and the separation pad 20 is attached so that it can be rotated integrally.

Based on FIG. 8 and FIG.
The drive configuration of each roller will be described.

In the document feeder 10, each roller is driven by a document supply motor M1 and a transport motor M2 which can rotate forward and backward. FIG. 8 is a diagram showing a drive transmission system on the original introduction side of the original supply motor M1. FIG. 9 is a diagram illustrating a drive transmission system on the document discharge side of the transport motor M2.

In FIG. 8, the rotational force of the normal rotation of the document supply motor M1 is transmitted from the pulley P16 to the pulley P36 via the timing belt T16 to each roller. The rotational force of the pulley P36 is transmitted in the order of the gear Z17, the gear Z19, and the gear Z18 attached to the drive shaft 34 of the document supply roller 19. The document supply roller 19 rotates in a direction for supplying the document.

The drive shaft 34 of the document supply roller 19 is also provided with a pulley P18. A drive shaft 34 is provided via a timing belt T2 stretched between a pulley P18 and a pulley P11 provided on a shaft 35 of the feeding roller 18.
Is also transmitted to the feed roller 18.

A drive shaft 34 of the document supply roller 19 has a pair of lifting arms 1 supporting the feeding roller 18.
One end of each of 8a and 18a is attached. When the drive arms 34 rotate in the direction of supplying the document (forward rotation of the document supply motor M1) and the elevating arms 18a, 18a rotate, the feeding roller 18 descends and comes into contact with the document. When the feed roller 18 comes into contact with the document, the drive shaft 34 idles with respect to the elevating arm 18a by the spring clutch A and the spring clutch B.

The registration drive roller 21a is connected to the motor M1 by a timing belt T3 stretched over a pulley P28 provided on the drive shaft 36 and a pulley P22 provided coaxially with the pulley P36. When the motor M1 is rotating forward, the one-way clutch OW1 provided in the pulley P28 does not rotate.

The reverse rotation force of the document supply motor M1 is transmitted from the pulley P16 to the pulley P36 via the timing belt T16. The rotational force of the pulley P36 is
The driving force is transmitted from a pulley P22 provided coaxially to a pulley P28 attached to a drive shaft 36 of the registration drive roller 21a via a timing belt T3. As a result, the registration driving roller 21a rotates in a direction for supplying the original.

At this time, the drive shaft 3 of the original supply roller 19
4, the reverse rotation force of the document supply motor M1 is also transmitted.
By the reverse rotation of the drive shaft 34, the elevating arm 18a rotates counterclockwise to raise the feeding roller 18. Due to the reverse rotation of the drive shaft 34, the document supply roller 19 also attempts to rotate in the reverse direction. However, the document supply roller 19 does not rotate due to the one-way clutch OW2 provided inside the document supply roller 19.

The ascending / descending arm 18a comes into contact with a regulating member (not shown) and its rotation is regulated. However, drive shaft 3
4 rotates idly with respect to the elevating arm 18a by the spring clutch C.

In such a configuration, the gear Z18 attached to the drive shaft 34 of the document supply roller 19 allows the user to rotate the exterior cover 10a together with the feeding roller 18 and the document supply roller 19 to open the document supply path 25. Then, it is separated from the gear Z19, and when closed, it meshes with the gear Z19.

In FIG. 9, the rotational force of the transport motor M2 is controlled by a pulley P provided on a drive shaft 37 of the transport motor M2.
26 to the pulley P46 via the timing belt T4. The rotational force transmitted to the pulley 46 is transmitted from the pulley P33 provided coaxially to the pulley P46 to the shaft 3 of the discharge conveyance drive roller 23a via the timing belt T6.
8 is transmitted to the pulley P32 attached to the pulley 8. As a result, the discharge / conveyance driving roller 23a rotates forward or backward.

Further, the rotational force transmitted to the pulley P32 is transmitted via a timing belt T7 to a pulley P31 attached to the shaft 39 of the introduction / conveyance driving roller 22a. As a result, the introduction conveyance drive roller 22a also rotates forward or backward.

The rotational force of the transport motor M2 transmitted to the pulley P46 via the timing belt T4 is transmitted from the pulley P42 provided coaxially with the pulley P46 to the shaft of the reverse transport drive roller 24a via the timing belt T5. The power is transmitted to a pulley P48 attached to the motor 40. Thereby, the reverse transport drive roller 24a is also rotated forward or backward.

Further, the pair of reverse conveying rollers 2 in FIG.
A pressure contact solenoid 30 is connected to the reverse conveyance driven roller 24b as a driving source for separating the roller 4 from the roller 4b. When the pressure contact solenoid 30 is excited (ON), the reverse conveyance driven roller 2
4b is pressed against the reverse transport drive roller 24a, and when the excitation is released (OFF), the pressure contact is released. When the excitation of the pressure contact solenoid 30 is released, the reverse transport driven roller 24b is pulled by a spring (not shown), and the reverse transport driving roller 2b is driven.
Move away from 4a.

As shown in FIG. 2, the document tray 15
A plurality of sensors S1, S2, S3 are provided in the document supply direction. ON of the plurality of sensors S1, S2, S3,
The length of the document placed on the document tray 15 is detected by the OFF state. In addition, the width direction of the document placed on the document tray 15 is detected from a volume (not shown) whose output changes according to the amount of movement of the side guide 17, and the document width detection result and a plurality of sensors S1 and S2 are detected. The CPU 31 determines the size of the document based on the length of the document detected by S3.

An empty sensor S4 is provided downstream of the document tray 15 in the document supply direction to detect that a document is placed on the document tray 15. A registration sensor S5 for detecting the end of the document supplied through the document supply path 25 is provided in the path for guiding the document. In front of the contact glass 2, there is provided a lead sensor S6 for detecting an end of the document.

On the downstream side of the contact glass 2, there is provided a document discharge sensor S 7 for detecting an end of the document discharged from the contact glass 2. Note that all the sensors including the registration sensor S5, the read sensor S6, and the document discharge sensor S7 for detecting the document sent in the path are again supplied from the document supply path 25 via the transport path 26, the discharge path 27, and the switchback path 28. It is arranged in a space inside a loop-shaped path returning to the transport path 26. By arranging the sensor in this way, it is not necessary to newly secure a space for mounting the sensor, and the document feeder 10 can be downsized.

The registration sensor S5 is a lever type sensor as shown in FIG. The sensor lever S5a of the registration sensor S5 is disposed so as to protrude in both paths of the document supply path 25 and the switchback path.

With this configuration, it is possible to detect both the original sent through the original supply path 25 and the original sent through the switchback path 28 with one sensor, and the original is used in the original feeder 10. The number of sensors to be used can be reduced. The document feeder 10 of the present embodiment uses a lever-type sensor as the registration sensor S5 for detecting a document sent through the document supply path 25 and the switchback path 28. A document can be detected.

These sensors S1 to S7 are connected to a CPU 31 for controlling the driving of the copying machine 51 as a whole. The CPU 31 controls the rotation of each of the motors M1 and M2 and controls the excitation of the press-contact solenoid 30 based on a detection signal from each sensor.

Next, the document feeder 10 having the above configuration
3 and 4 showing the reverse transport drive roller 24a, FIGS. 11 to 24 which are flowcharts, and FIG. 25 schematically showing the transport status of the original. 28 will be specifically described.

First, a one-sided mode for reading one side of a document will be described with reference to FIGS.

When a document is placed on the document tray 15 and the empty sensor S4 is turned on, the document supply motor M1 is normally rotated by the CPU 31 and the first document D1 is placed in the document feeder 10. Supplied (S1, S
2).

At this time, the feed roller 18 and the document supply roller 19 rotate in the document feed direction. However, the registration roller pair 21 does not rotate due to the action of the one-way clutch OW1. The registration sensor S5 detects the leading edge of the sent original. Then, after a predetermined time t1 after receiving the detection signal, the CPU 31 sets the document supply motor M1
Is temporarily stopped (S3, S4, S5). When the document supply motor M1 is stopped, the leading edge of the document is pressed against the nip of the registration roller pair 21, and the vicinity of the leading edge of the document is deflected. Then, the leading edge of the document is aligned with the nip, and the document that has been inclined is straightened (see FIG. 25A).

After the document has been stopped, the CPU 31
The document supply motor M1 is controlled to rotate in the reverse direction, the transport motor M2 is rotated, and the press-contact solenoid is excited (S6, S7). At this time, the feeding roller 18
Rise away from the manuscript. The document supply roller 19 is
The rotational force is cut off by the one-way clutch OW2.
The registration drive roller 2 of the registration roller pair 21
1a is rotated in the document feeding direction.

The document D1 is conveyed from the document supply path 25 to the conveyance path 26 by the rotation of the motors M1 and M2, and the passage of the leading end is detected by the read sensor S6. After the detection, a time t3 elapses and the document supply motor M1 stops rotating. The transport motor M2 is temporarily stopped (S
8, S9, S10) (see FIG. 25 (b)).

When the CPU 31 receives the reading and conveying signal from the copying machine body 1, the CPU 31 rotates the conveying motor M2 again. The front side (one side) of the document D1 is
The image is read by sub-scanning by the image reading unit 33 (S11, S12). At this time, the original D1 is
The front end of the flapper 29 arranged so as to close the document discharge path 27 is pushed up and conveyed onto the document discharge tray 16.

After the document D1 is sent to the document discharge tray 16, the registration sensor S5 detects the passage of the rear end of the document D1. Then, the CPU 31 checks whether or not there is a next document on the document tray 15 with the sensors S1, S2 and S3, and when there is a document on the document tray 15, the first document D
As in the case of the first document, the supply control of the second document D2 is started (S
13, S14, S15).

When supplying the second original D2, the CPU 3
Reference numeral 1 denotes a case where the original supply motor M1 is rotated forward in the same manner as in the case of the original, and the feeding roller 18 and the original supply motor 19
To rotate. The second original D2 is a registration roller pair 2
The skew correction is performed by abutting on the nip of No. 1 (S
16 to S19) (see FIG. 25C).

The CPU 31 rotates the original supply motor M1 in the reverse direction, and stops the original after a predetermined time t3 since the read sensor S6 detects the leading end of the next original. Then, the transport motor M2 is also stopped (S20 to S23).

Here, the second original D2 is stopped with its leading end located in front of the contact glass 2 and the first original D1 is stopped with its rear end sandwiched between the pair of reverse transport rollers 24. (See FIG. 26A).

When the CPU 31 receives the reading and conveying signal from the image reading apparatus main body 1, the CPU 31 rotates the conveying motor M2 again. The surface of the second document D2 is sub-scanned by the above-described image reading unit 33 to read an image (S24, S25). During reading of the second document D2, the first document D1 is discharged onto the document discharge tray 16 (see FIG. 26B).

The passage of the rear end of the document D2 is detected by the registration sensor S
5 is detected, the CPU 31 sets the empty sensor S4
Confirms whether the presence of the next document has been detected. If the next document exists, the same as that of the second document D2, 3
The feeding operation of the first document is started. Thereafter, as long as the empty sensor S4 detects the presence of the original (S14 to S25), the same processing is performed by the CPU 31 for the fourth and fifth originals.

If the original is the last original, (S1
In 4), the empty sensor S4 is turned off. Accordingly, the CPU 31 stops the transport motor M2 and releases the excitation of the pressure contact solenoid 30 after the time t5 required for the document to be discharged to the document discharge tray 16 after the discharge sensor S7 detects the trailing end of the last document. Then, all the processing operations of the original are terminated (S26, S27, S2
8).

Next, a duplex mode for reading both sides of a document will be described with reference to FIGS.

When the empty sensor S4 detects that a document is placed on the document tray 15, the first document D1 is moved to the document supply motor M1 in the same manner as in the single-sided mode (S1) to (S10). The tip of the pair of registration rollers 21 abuts against the nip of the pair of registration rollers 21 by the feed roller 18 and the document supply roller 19 which are rotated by the forward rotation of the skew correction, thereby correcting skew. After the leading edge of the document D1 conveyed by the reverse rotation of the document supply motor M1 and the normal rotation of the conveyance motor M2 is detected by the read sensor S6, the document supply motor M1 and the conveyance motor M2 are temporarily stopped. At this time, the document D1 stops when the leading end reaches a position short of the contact glass 2. Also, the pressure contact solenoid 30 is excited, and the reverse conveyance driven roller 24b is pressed against the reverse conveyance drive roller 24a (S51 to S60) (see FIG. 27A).

When the CPU 31 receives the reading and conveying signal from the copying machine main body 1, it rotates the conveying motor M2 forward. The original is sent onto the contact glass 2, and the image on the front surface is sub-scanned and read by the image reading unit 33. The document D1 read by the contact glass 2 is guided to the document discharge path 27 (S61, S6).
2).

The document D1 guided to the document discharge path 27 is
The front end pushes up the front end of the flapper 29 arranged so as to close the document discharge path 27 and is conveyed onto the document discharge tray 16. In this conveyance state, after the original discharge sensor S7 detects the rear end of the original D1, the rear end of the original D1
When the time t11 required to pass the position 9 passes, the CPU 31 stops the rotation of the transport motor M2.
Thereafter, the document D1 stops with the rear end side sandwiched between the pair of reverse transport rollers 24 (S63, S64, S65).
(See FIG. 27B).

Thereafter, the CPU 31 rotates the transport motor M2 in the reverse direction (S66, S67). As a result, the reverse transport drive roller 24a rotates in the reverse direction, and the document D1 is transported by switchback. The document D <b> 1 is guided by the document guide surface 29 a of the flapper 29 moving to a position that closes the document discharge path 27, and is guided along the switchback path 28. The transport motor M2 rotated in the reverse direction is stopped after a lapse of a predetermined time t1 after the registration sensor S5 detects the leading end of the document D1 guided to the switchback path 28 (S6).
8, S69, S70) (see FIG. 27 (c)). During this time, the original is abutted against the nip of the pair of registration rollers 21 to bend and the skew is corrected.

Then, the CPU 31 rotates the document supply motor M1 in the reverse direction to re-supply the document D1 (S7).
1). The reverse rotation of the document supply motor M1 causes the registration drive roller 21a to rotate in the document supply direction. Time t1 at which the leading edge of document D1 is securely nipped into registration roller pair 21
After two passes, the CPU 31 releases the excitation of the pressure contact solenoid 30, moves the reverse transport driven roller 24b downward to separate it from the reverse transport drive roller 24a, and rotates the transport motor M2 forward (S72, S73).

Here, while the reverse transport roller pair 24 is performing the switchback operation, the original is transported only by the reverse transport roller pair 24, so that the left and right reverse transport drive rollers shown in FIG. If it is cylindrical and has a large difference in outer diameter as in 124a, it is skewed and conveyed. For this reason,
The reverse transport drive roller 124a is polished to minimize the difference in outer diameter. However, due to processing, the outer diameter of the roller end may increase, or burrs may occur at the corners.

When the transport motor M2 rotates forward, the reverse transport drive roller 124a rotates in the direction opposite to the traveling direction of the document D1 (see FIG. 4). Because the roller 124a is urged toward the roller 124a and is stiffened, the reverse transport driving roller 124a
The rollers are strongly rubbed against the roller ends and conveyed.
Therefore, a large amount of dust such as roller shavings (rubber scraps) is generated at the end of the roller, and a part of the generated dust adheres to the original D1 and reaches the contact glass 22 at the image reading position 9 of the image reading unit 33. Sent.

The document D1 is conveyed while being inverted along the document supply path 25, and when the leading end is detected by the lead sensor S6, the CPU 13 stops the conveyance motor M2 and the document supply motor M1 after a predetermined time t3. (S74,
S76). Thereafter, the CPU 31 rotates the transport motor M2 again according to the read transport signal from the copying machine body 1. The image on the back surface of the document D1 is sub-scanned and read by the image reading unit 33 (S77, S78). At this time, the dust carried by the document D1 stays on the contact glass 22 at the image reading position, and
When the size becomes 0 μm or more, the image is read by the image reading unit 33 and appears as a black streak on the image copied on the sheet by the copying machine 51.

In order to prevent such a problem from occurring, a relief portion 24d having a tapered shape (conical frustoconical shape) is formed at the roller end of the reverse transport driving roller 24a of this embodiment as shown in FIG. It is formed. Therefore, in the document feeder 10 of the present embodiment, the escape portion 24d allows the outer diameter of the roller end of the reverse transport driving roller 24a to be smaller than the outer diameter of the nip (intermediate portion) with the reverse transport driven roller 24b. In addition, the contact between the original D and the end of the roller is avoided, the generation of dust such as shavings of the reverse transport driving roller 24a is reduced, and the generation of black stripes is reduced. Escape portions may be formed at both ends of the reverse conveyance driven roller 24b. In this case, contact between the reverse transport driven roller 24b and the document is also avoided, and the generation of dust is further prevented.

Further, by forming a relief portion 24d at the roller end of the reversing transport drive roller 24a, it is possible to prevent the curled original from locally contacting the roller end even when the waist rib 61 is not provided. Accordingly, the occurrence of black stripes can be similarly reduced.

Further, when there is no waist rib 61, the escape portion may be formed on at least one of the reverse transport driving roller 24a and the reverse transport driven roller 24b.

After the above (S72, S73), when the registration sensor S5 detects the trailing edge of the original D1, the CPU 31
Excites the pressure contact solenoid 30 to press the reverse transport driven roller 24b against the reverse transport drive roller 24a. Then, when the time t11 has elapsed since the document discharge sensor S7 detects the rear end of the document D1, the CPU 31 stops the rotation of the transport motor M2. The document D1 is stopped with its trailing end sandwiched between the pair of reverse transport rollers 24 (S79 to S8).
3) (see FIG. 28 (c)).

Then, in order to discharge the document D1 onto the document discharge tray 16 in the same order as the pages, the CPU 31 rotates the transport motor M2 in the reverse direction, and
The leading edge of the document D1 is abutted against the nip of the registration roller pair 21 to correct the skew of the document, the document supply motor M1 is rotated in the reverse direction, and the document is conveyed in reverse along the document supply path 25, and the document of the read sensor S6 is read. The rotation of the document supply motor M1 is stopped by detecting the leading end of D1 (S84 to S90).

When the CPU 31 rotates the transport motor M2 forward and releases the excitation of the pressure contact solenoid 30, the original D1 is transported onto the contact glass 2, but the original D1 is not scanned for reading. Without stopping before the contact glass 2,
The document is conveyed to the document discharge path 27. (S91 to S9
4).

When the registration sensor S5 detects the trailing end of the document D1 in the course of transporting the document D1 to the document discharge path 27 (S95), the CPU 31 causes the press-contact solenoid 30 to rotate.
To excite the roller pair 24 and check the presence or absence of a document on the document tray 15 (S96).
If there is a second document D, the supply operation of the second document D2 is started in the same manner as the first document D1.

The supply control process for the second document D2 is similar to the case of the previous document D1, in which the feed roller 18 and the document supply motor M1 rotate by the forward rotation of the document supply motor M1 to move the document D2 to the registration roller pair. The skew of the document D2 is corrected by abutting the nip 21 (S94 to S10).
1) (see FIG. 28 (c)).

The original supply motor M1 is connected to the CPU 3
1. Reverse rotation by 1. Document D2 is document supply path 2
5 while reading the second original D2.
The first document D1 is discharged to the document discharge tray 16 (S
102).

Thereafter, the second original D2 is processed in the control steps (S58 to S96) in the same manner as the first original D1, so long as the empty sensor S4 detects the presence of the original. Similar processing is performed for the third and fourth originals.

Since the empty sensor S4 is in the OFF state in (S100), the last document is discharged to the document discharge tray 16 after the discharge sensor S7 detects the trailing end of the last document. After the time t5 required for the rotation, the rotation of the transport motor M2 is stopped, and the pressure contact solenoid 30
And the processing of all the originals is terminated (S
103 to S105).

The automatic document feeder 10 according to the present invention comprises:
An original is provided with an original supply roller 19 and a separation pad 20 to
An original supply path 25 for separating the original into sheets and supplying the original to the contact glass 2, an original discharge path 27 for discharging the original passing over the contact glass 2, and turning the original discharged from the contact glass 2 upside down again Contact glass 2
A reverse feed drive roller 24a and a reverse feed drive roller 24a that can be rotated forward and backward.
A reverse transport roller pair 24 for performing switchback comprising a reverse transport driven roller 24b which can be freely contacted with and separated from,
Reverse transport drive roller 24a and reverse transport driven roller 24b
Since at least one of the rollers has a frusto-conical shape having a substantially tapered end, local rubbing with the document at the end of the roller is eliminated, and the generation of dust such as roller shavings is reduced. Thus, the occurrence of black streaks can be reduced.

Since the copying machine 51 is provided with a document feeder in the main body of the apparatus, the dust is hardly generated and the dust is prevented from adhering to the contact glass 2 at the image reading position. A high-quality image can be formed on a sheet without causing black streaks in an image copied on a sheet based on information obtained by reading an original by the image reading unit 33.

[0092]

According to the automatic document feeder of the present invention, at least one of the pair of rollers of the reverse conveying means is cut off at both ends of at least one of the rollers so that both ends of the roller do not contact the document. Since the conical relief portion is formed, local rubbing with the document at the roller end is eliminated, and dust is not generated from the roller that reverses and transports the document.
It is possible to prevent dust from staying at the image reading position.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a copying machine which is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic front sectional view of the document feeder according to the embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of the document feeder in FIG. 2;

FIG. 4 is a diagram showing a positional relationship between a reverse conveyance driving roller and a waist rib.

FIG. 5 is a view of a pair of reverse conveying rollers viewed from an upstream side in a document conveying direction.

FIG. 6 is a diagram illustrating a pair of reverse conveying rollers for describing the features of the present invention, as viewed from the upstream side in the document conveying direction.

FIG. 7 is a schematic front sectional view of the document feeder when an exterior cover is opened.

FIG. 8 is a diagram showing a drive transmission system on the document introduction side of the document supply motor.

FIG. 9 is a diagram illustrating a drive transmission system on a document discharge side of a conveyance motor.

FIG. 10 is an enlarged view of a registration sensor and a peripheral portion thereof.

FIG. 11 is a flowchart of a single-sided mode for reading one side of a document in the document feeder according to the embodiment;

FIG. 12 is a flowchart continued from FIG. 11;

FIG. 13 is a flowchart continued from FIG. 12;

FIG. 14 is a flowchart continued from FIG. 13;

FIG. 15 is a flowchart continued from FIG. 13;

FIG. 16 is a flowchart of a duplex mode for reading both sides of a document in the document feeder of the present embodiment.

FIG. 17 is a flowchart continued from FIG. 16;

FIG. 18 is a flowchart continued from FIG. 17;

FIG. 19 is a flowchart continued from FIG. 18;

FIG. 20 is a flowchart continued from FIG. 19;

FIG. 21 is a flowchart continued from FIG. 20.

FIG. 22 is a flowchart continued from FIG. 21.

FIG. 23 is a flowchart continued from FIG. 22.

FIG. 24 is a flowchart continued from FIG. 23.

FIG. 25 is a diagram for explaining the operation of the document feeder corresponding to the flowchart of the one-sided mode for reading one side of the document. FIG. 3A is a diagram illustrating a state in which the leading edge of a first document is brought into contact with a nip of a pair of registration rollers to correct skew of the document. FIG. 5B is a diagram illustrating a state in which the leading edge of the first document is fed to the image reading position. FIG. 5C is a diagram illustrating a state in which the skew of the original is corrected by bringing the leading end of the second original into contact with the nip of the pair of registration rollers while discharging the first original to the original discharge tray. .

FIG. 26 is an explanatory view of the operation continued from FIG. 25; FIG. 7A is a diagram illustrating a state in which the leading end of the second document is being sent to an image reading position while the first document is being discharged to a document discharge tray. FIG. 11B is a diagram illustrating a state in which the discharge of the first document to the document discharge tray is completed, and the second document is being conveyed while reading the image at the image reading position.

FIG. 27 is a diagram for explaining the operation of the document feeder corresponding to a flowchart of a duplex mode for reading both sides of a document. FIG. 3A is a diagram illustrating a state in which the leading edge of a first document is fed to an image reading position. FIG. 5B is a diagram illustrating a state where most of the original has been discharged to the original discharge tray in order to reversely transport the first original. FIG. 3C is a diagram illustrating a state in which the pair of reversing conveyance rollers is reversed and the first document is sent to the switchback path.

FIG. 28 is an explanatory view of the operation continued from FIG. 27; FIG. 5A is a diagram illustrating a state in which a first document is being conveyed through a switchback path and a document discharge path. FIG. 4B is a diagram illustrating a state in which most of the first document is temporarily discharged to a discharge tray in order to reverse the document after image reading and discharge the document in page order. FIG. 4C is a diagram illustrating a state in which a document that has been turned upside down is being discharged.

FIG. 29 is a schematic front sectional view of a conventional document feeder.

[Explanation of symbols]

 D Document 1 Main body of copier (image forming apparatus) 7 Body of document feeder 9 Image reading position 10 Document feeder 12 Transport unit (document transport unit) 14 Switchback unit (reverse transport unit) 24 Reverse transport roller pair (1) A pair of rollers) 24a reverse transport driving roller (one roller) 24b reverse transport driven roller 24d tapered (conical frustoconical) relief section 33 image reading section (image reading means) 54 photosensitive drum (image forming means) 51 Copying machine (image forming apparatus) 61 Waisting rib (waisting means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/04 H04N 1/12 Z F-term (Reference) 2H076 BA24 BA42 3F049 AA03 CA04 DA12 DA14 EA17 EA28 LA02 LB02 3F053 BA03 BA13 BA19 BA23 EA03 EB01 EB04 EC01 ED17 LA03 LB02 3F100 AA04 BA27 CA01 CA11 DA01 DA04 EA02 5C072 AA01 AA05 BA20 NA01 NA07 WA01 WA02 XA01

Claims (3)

[Claims] 1. A document conveying means for conveying and sending the document to an image reading position for reading an image of the document; and receiving the document from the document conveying means and once conveying the document to a downstream side of the image reading position, Reversing conveyance means having a pair of rollers for feeding and feeding the document upstream of the document conveyance means, wherein both ends of at least one of the pair of rollers do not contact the document. As described above, the document feeder is characterized in that truncated conical relief portions are formed at both ends of the at least one roller. 2. The apparatus according to claim 1, further comprising waving means for raising a part of the document conveyed by the pair of rollers, wherein the relief portion is formed on a roller on the side where the document is raised. 2. The document feeder according to 1. 3. The document feeder according to claim 1 or 2, image reading means for reading an image of the document sent by the document feeder, and image information of the document read by the image reading means. And an image forming means for forming an image on a sheet.