JPH11184172A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect overlapped-feeding and to prevent the order missing of a document and jamming at a switchback path by guiding the documents before and after the switchback to the same feeding path and detecting the length of each document by the same detecting sensor. SOLUTION: A lead sensor S3 is arranged near the upstream of an image reading position 5a. The lead sensor S3 is prepared for detecting the leading end of the document in order to stop feeding the document once before reading an image, and making the document in a standby state. The lead sensor S3 also functions as a detecting sensor for detecting the document length in the feeding direction, and the number of pulses of a pulse motor 25 during the detection of the document length from the leading end to the trailing end is counted by the sensor S3 so as to be transmitted to a judging means. Each document length before and after the switchback is detected by the same lead sensor S3. And, both numbers of pulses detected before and after the switchback are stored by the judging means, and one is compared with the other, and then, in the case a difference between both is equal to or exceeding a prescribed specific number of pulses, it is judged by the judging means that the abnormal feeding of the document occurs, that is, the overlapped feeding occurs.

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 for conveying a document to a predetermined image position in an image reading apparatus such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, as an automatic document feeder of this type, for example, originals stacked on a paper feed tray are fed one by one to a reading position of a copying machine main body, and after reading a surface image of the original. The document is switched back, the leading and trailing edges of the document are reversed, the document is turned upside down and fed again to the reading position, and after scanning the back side as well as the front side, the document is transported at high speed to the output tray. There is a type that discharges to

[0003]

By the way, when a document is fed out of the paper feed tray and sent out to the feeding path in a state where two documents are overlapped, and a conveyance error is caused by a so-called double feed,
When a document is turned over, one sheet of the document may be left in the reversing section.In such a case, the order of the document may be lost, and the document left in the switchback path may be complicated with the next succeeding document. It could cause a jam.

Accordingly, the present invention guides a document before switchback and after switchback to the same transport path, and detects the length of the document by the same detection sensor to make the detection condition constant, thereby preventing a double feed which is a transport abnormality. The present invention is to provide an automatic document feeder capable of reliably detecting an original and preventing a document from being out of order and causing a document jam in a switchback path.

[0005]

According to a first aspect of the present invention, there is provided an automatic document feeder for conveying a document stacked on a paper feed tray to an image reading position. An automatic document feeder comprising: a document reversing means for reversing a leading end and a trailing end of a document read at an image reading position and leading the document to a path of the transporting means; A detecting means for detecting the length of the original before and after the reverse rotation in the original transport direction, and if the detection results of the lengths before and after the reverse rotation of the original by the detection means differ by a predetermined value or more, the transport of the original is abnormal. And a judging means for judging.

In the automatic document feeder according to a second aspect of the present invention, the detection result of the detection means is such that the length of the original after the reverse rotation of the original is shorter than the length of the original before the reverse rotation of the original by a predetermined amount or more. In this case, it is determined that the conveyance of the document is abnormal.

According to a third aspect of the present invention, there is provided an automatic document feeder for prohibiting a subsequent document from being fed to the image reading position on the basis of the determination of a document conveyance error. Features.

The automatic document feeder according to a fourth aspect of the present invention is characterized in that the detecting means is arranged on a path of a conveying means for guiding a document to an image reading position.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic document feeder according to the present invention will be described below in detail with reference to the accompanying drawings. FIGS. 1 and 2 are schematic diagrams showing the configuration of the automatic document feeder according to this embodiment. The automatic document feeder 1 according to this embodiment includes a paper feed tray 2 for placing a document.
A document feeder 4 provided in the vicinity of the paper feed port 3; a registration roller 7 for abutting and aligning the leading end of the document fed by the document feeder 4; Document conveying means 8 for conveying the document to the position 5a, document discharging means 9 for discharging the document read by the image reading means 5b of the copying machine main body H facing the image reading position 5a, and paper discharging. Document reversing means 10 provided in the middle of the path 32; The original placed on the paper feed tray 2 is sequentially conveyed toward the image reading position 5a, and after the front side image of the original is read, the original enters the switchback path by the original reversing means 10 and the front and rear ends in the conveying direction. Is reversed, guided again to the transport path 6 by the document transport means 8, and the image on the back side of the document is read at the image reading position 5a.

The copying machine main body H includes a transparent glass 11 for reading an image by the image reading means 5b at the time of automatic document feeding.
And a platen 12 for moving and scanning the image reading means 5b when a document such as a book is placed.

The paper feed tray 2 is arranged to be inclined toward the paper feed port 3 of the apparatus main body, and is provided with a guide plate 13 movable in the width direction of the original. The guide plate 13 detects the width of the document, is connected to a variable resistor via a rack and a pinion gear, and detects the resistance value when the document is moved in the width direction. Further, the paper feed tray 2 is provided with two size detection sensors S1 for detecting the document length in the feeding direction in the feeding direction. This size detection sensor S
Reference numeral 1 denotes, for example, a limit switch, an optical sensor, or the like, and the size of the document is detected by a combination with the guide plate 13.

A document feeder 4 is installed near the paper feed port 3 and has a paper feed roller 14 as a paper feeder capable of displacing the document placed on the paper feed tray 2 in the thickness direction. An arm 15 rotatably supports the feed roller 14 and a separation roller 16 located at the other end of the arm 15. The paper feed roller 14 is normally in the standby position, moves from the machine position to the paper feed position by the operation of the paper feed clutch 17a, rotates following the rotation of the separation roller 16, and sends out the original on the paper feed tray 2. . The separation roller 1 is driven by the paper feed clutch 17b that operates simultaneously with the reverse rotation of the DC motor 18.
6 rotates and separates the originals one by one between the separation pad and the originals and sends out the originals to the transport path 6. An empty sensor (not shown) is provided between the paper feed roller 14 and the separation roller 16 and detects the presence or absence of a document on the paper feed tray 2.

A registration sensor S2 is arranged downstream of the separation roller 16, and a registration roller 7 is arranged near the registration sensor S2. The registration roller 7 includes the driving roller 2
The DC motor 18 rotates the drive roller 20 at a predetermined timing. The leading end of the document comes into contact with the registration roller 7 to be aligned, and after waiting for a certain period of time, the driving roller 20 rotates, and the document is sandwiched between the driven roller 21 and sent to the transport path 6.

The document conveying means 8 includes a conveying roller 22 for winding and conveying the document, and pinch rollers 23 and 24 disposed on the peripheral surface of the conveying roller 22. The conveying roller 22 and the pinch rollers 23 and 24, the document is gripped and conveyed to the image reading position 5a. The transport roller 22 is
The rotation timing, stop angle, rotation speed, and the like are controlled by the drive pulse of the pulse motor 25.

A read sensor S3 is disposed near the upstream of the image reading position 5a. The read sensor S3 detects the leading edge for temporarily stopping the conveyance of the document before reading the image and for making the document stand by. The document waiting just before the image reading position 5a starts to be conveyed again by the reading start signal from the copying machine main body H side, and when passing over the transparent glass 11, the image of the document is read by the image reading means 5b. Reading is performed. In this embodiment, the read sensor S3 also serves as a detection sensor for detecting the length of the document in the transport direction.
The number of pulses of the pulse motor 25 is counted while the read sensor S3 detects the length from the leading edge to the trailing edge of the document, and this is transmitted to the determining means (not shown). The same read sensor S3 detects the length of the original before switchback and the length of the original after switchback. The judgment means stores the number of pulses detected before and after switchback,
By comparing the two, if there is an opening that is equal to or greater than a predetermined number of pulses, it is determined that double feeding, which is an abnormality in document conveyance, has occurred.

The document discharge means 9 includes a paper discharge tray 37 disposed below the paper feed tray 2 and a paper discharge tray 37.
A pair of upper and lower guides 35 for guiding the discharged document upward, and a pair of paper discharge rollers 3
6 is provided. The paper discharge roller 36 is connected to the transport roller 22.
And at the same speed by the common pulse motor 25. Note that a paper discharge sensor S5 is disposed near the paper discharge roller 36, and detects completion of document discharge.

The document reversing means 10 is located on the downstream side of the document reading section and has an introduction guide 27 opened like a trumpet, a pair of reversing rollers 28 arranged near the guide, and a rear side of the reversing roller 28. And a switchback path 29 provided. Pinch rollers 30 and 31 are disposed at the entrance end and the exit end of the introduction guide 27, respectively.
2 and feeding / discharging to the document reversing means 10, and the pinch roller 31 at the exit end also has a function as a reversal resist when reading the back side of the document G. That is, the pinch roller 31 is in pressure contact with the transport roller 22 and rotates together with the drive of the transport roller 22. However, during registration, the rotation of the transport roller 22 is stopped and the original G Align the tip with the tip. The reversing roller 28 can be opened and closed by a solenoid 33 and can also be rotated forward and backward by a sheet feeding reversing roller 28. The forward and reverse rotations of the reversing roller 28 switch the document conveyance direction from the leading end to the trailing end. Let it out before sending. The reversing sensor S is located near the reversing roller 28.
4 are arranged.

As shown in FIG. 1, the switchback path 29 of the document reversing means 10 is a hermetic seal formed between the lower surface of the paper discharge tray 37 and the upper surface of a platen cover 50 that covers the platen 12. It is configured using space.
The platen cover 50 is rotatably supported at the back of the switchback path 29 with respect to the main body of the automatic document feeder so that the switchback path 29 can be opened and closed. This opening / closing direction is the same as the direction in which the main body of the automatic document feeder opens and closes with respect to the main body H of the copying machine, and generally has a structure in which the front operation panel side of the main body H of the copier opens and closes.

Around the transport roller 22, flappers 38 and 39 for switching the transport direction of the document are provided near the entrance of the document reversing means 10 and near the entrance of the document discharge means 9, respectively.
Are arranged. A flapper 38 disposed in the introduction guide 27 switches between the document reversing means 10 and the paper discharge path 32, and a flapper 39 disposed near the downstream side of the pinch roller 31 connects the paper supply path 6 and the document discharge path. Switching to the means 9. These flappers 38 and 39 are switched together by a solenoid 40.

Further, in this embodiment, the registration rollers 7
A document evacuation path 41 branching downward from the conveyance path 6 is formed between the pinch roller 23 and the pinch roller 23 pressed against the conveyance roller 22. The document evacuation path 41 is normally urged upward by a spring and the flapper 4 whose leading end projects into the conveyance path 6.
2 and a guide plate 43 which forms a curved retreat path between the lower surface of the flapper 42 and the guide plate 43. Flapper 4
Reference numeral 2 denotes a sheet that is pushed downward when the document is conveyed thereon and sinks from the conveyance path 6, whereas when there is no document, the tip of the flapper 42 projects into the conveyance path 6 and the retreat path is opened.

Next, conveyance control when reading an original using the automatic document feeder will be described with reference to the flowcharts of FIGS. First, when a document is set on the paper feed tray 2, the empty sensor is turned on to detect the presence or absence of the document. The document size is immediately detected from the size in the transport direction detected by the size detection sensor S1 and the size in the width direction detected from the change in the variable volume, and a signal indicating the document size is sent to the copying machine main body H side. When the start button on the copier main body H side is turned on, the paper feed clutch 17
The DC motor 18 starts to rotate forward by operating a and 17b.
The forward rotation of the DC motor 18 causes the arm 15 of the paper feed roller 14 to rotate, and the separation roller 16 and the paper feed roller 14 to rotate, so that the uppermost document among the documents set on the paper feed tray 2 Is fed out, and the advance of the original is started, and one original is separated and fed by the separation roller 16.

The leading edge of the fed original is registered with a registration sensor S
2 is detected, a predetermined time after the detection, the leading edge of the document is abutted against the registration roller 7 to be aligned, and the D
The C motor 18 is stopped to wait for the original to complete the advance of the original. After a predetermined time from the stop of the DC motor 18, the paper feed clutch 17b is turned on, the nip conveyance of the document by the registration roller 7 is started, and the pulse motor 25 starts rotating, and the document delivered from the registration roller 7 is The sheet is fed by the conveying roller 22 and the pinch rollers 23 and 24. When the leading end of the document conveyed from the registration roller 7 is nipped by the conveyance roller 22 and the pinch roller 23, the paper feed clutch 17b is turned off, and the driving of the registration roller 7 is stopped.

When the leading edge of the document is detected by the read sensor S3, the pulse motor 25 is stopped after a predetermined time, the conveyance of the document is stopped, and the apparatus enters a reading standby state. Next, the pulse motor 2 is turned on by a reading start signal from the copying machine main body H.
5 starts rotating again, and drives the transport roller 22 to transport the original to the original reading section 5b at the reading speed, and the image reading of the original surface is started. At the same time, the transport pulse counter is cleared and the count of the transport pulses of the pulse motor 25 is started. When reading of the original surface is completed, the read sensor S
When 3 is turned off, the counting of the transport pulse is completed and sent to the determination means and stored as data. If a document is transported abnormally due to double feeding of the document, the document is slightly shifted in the transport direction while passing through the transport path 6, and thus is counted more than the original transport pulse of the document.

The document after reading enters the switchback path 29 of the document reversing means 10, and its rear end is nipped by the reversing roller 28 and temporarily stopped. After a predetermined time, the reversing roller 28 is reversed, and the document is fed out after being switched back from the leading end to the trailing end in the transport direction of the document. The original sent out from the switchback path 29 is guided to the transport path 6 with the original surface reversed, and the leading end of the original is set on the read sensor S3 again. Then, similarly to the front side of the original, the transport roller 22 is rotated by a reading start signal from the copying machine main body H, and the original is sent to the original reading section 5b to start reading the back side of the original. At the same time as the start, the transport pulse counter is cleared and starts counting. When the reading of the back side of the document is completed and the read sensor S3 is turned off, the count of the transport pulse is completed, and the counted number is sent to the determination means and stored as data. After the reading of the back side of the document is completed, the document is returned to the switchback path 2 of the document reversing unit 10 again.
9 and temporarily stop. At this time, the pulse data at the time of reading the back surface is subtracted from the pulse data at the time of reading the front surface by the judging means. If the subtraction value is smaller than a predetermined number of pulses, it is determined that there is no double feeding which is a conveyance abnormality. On the other hand, if the subtraction value is larger than the predetermined number of pulses, it is determined that there is a double feed that is a transport abnormality. This is because in the switchback path 29, the reversing roller 28 nips the trailing end of the original (the leading end of the original after being inverted), so that one of the multi-fed originals is not nipped and the switchback path 29 is left as it is. This is because the conveyance counter counts the length of one leaf at the time of reading the back surface, so that a difference in the number of pulses appears. In addition, an allowable range is provided in consideration of a document slip at the time of conveyance, for example, an allowable error of 5 mm is provided in terms of a document length, and a conveyance error due to double feeding is determined only when a difference of more than 5 mm occurs. I'm trying to make a decision.

When it is determined that there is no double feed which is a conveyance abnormality, the operation is continued as it is, and the document whose back side has been read is switched back again by the document reversing means 10 and then conveyed to the document discharge means 9 to be discharged. The paper is discharged onto the paper tray 37. Further, the subsequent document is fed out from the paper feed tray 2, waits at the document alignment position, and is guided to the transport path 6. On the other hand, when it is determined that there is a double feed that is a transport abnormality, the document transport operation of the automatic document feeder 1 is stopped and the copy operation in the copying machine main body H is stopped. in this case,
The paper discharge operation of the document whose back side has been read is continued, and the feeding of the subsequent document waiting at the document alignment position (registration position) is prohibited. When a subsequent document is waiting on the paper feed tray 2, the feeding of the document from the paper feed tray 2 is prohibited. The copy on the front side of the original is stopped on the copy machine main body H side after the front side copy is completed. Further, the copier main body H displays that the jammed document is left in the switchback path 29, determines that a page in which the page misalignment has occurred due to the double feed is determined as a defective copy, and returns the number of returned documents. Is displayed. As a double feed process, the jammed document left in the switchback path 29 is removed by opening the platen cover 50, and the subsequent document in the alignment position is located above the registration roller 7 as shown in FIGS. Open the cover 51 located at and pull it out. The taken out document is reloaded on the top of the paper feed tray 2 and the feeding is started again.

In the above embodiment, the lead sensor S3 is used as a detection sensor for detecting the length of the original, and the length of the original in the transport direction is detected in a stable transport state when reading the original. Of course is not limited to the positions shown in FIGS. 1 and 2, and it is also possible to detect by means other than the lead sensor S3. Further, in the above-described embodiment, the double feed determination is performed when the original whose back surface has been read is switched back in the switchback path 29. It is a matter of course that the automatic document feeder may be stopped by judging the double feed immediately after detecting the original document length.

[0027]

As described above, according to the automatic document feeder according to the present invention, the length of the original is detected by being guided into the same transport path before and after switchback of the original. In this case, the detection can be performed under the same transport condition in any case, and there is an effect that the double feed which is a transport abnormality can be reliably detected by reducing the detection error.

Further, according to the automatic document feeder according to the present invention, when the detection result by the detecting means is shorter than the document length before the document reversal by a predetermined length or more, the document is transported abnormally. , It is possible to reliably detect a transport abnormality due to double feeding.

Further, according to the automatic document feeder of the present invention, when it is determined that the conveyance is abnormal, the feeding of the subsequent document is prohibited. The manuscript can be prevented beforehand.

Further, according to the automatic document feeder according to the present invention, since the detecting means for detecting the length of the document is arranged in the path of the conveying means, the length of the document can be detected in a stable conveying state. And the detection error is reduced accordingly.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an automatic document feeder according to the present invention.

FIG. 2 is an enlarged view of a main part of the automatic document feeder according to the present invention.

FIG. 3 is a flowchart illustrating conveyance control when reading the front side of a document.

FIG. 4 is a flowchart illustrating conveyance control when reading the back side of a document.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic document feeder 2 Paper feed tray 5a Image reading position 6 Transport path 8 Document transport means 10 Document reversing means 29 Switchback path S3 Read sensor (Document length detecting means)

Continued on the front page (72) Inventor Satoru Endo 2970 Ishikawa-cho, Hachioji-shi, Tokyo In-house (72) Inventor Masanobu Kono 2970 Ishikawa-cho, Hachioji-shi, Tokyo In-house Konica Incorporated (72) Inventor Eiichi Kubo Minamikoma, Yamanashi 430 Kobayashi, Masuho-gun, Gunma Nisca Corporation

Claims (4)

[Claims] A transport unit that guides a document stacked on a paper feed tray to an image reading position; and a document that guides the document read at the image reading position in a reverse direction in a transport direction to guide the document to a path of the transport unit. An automatic document feeder provided with a reversing means; a detecting means for detecting a length of the document in which the leading and trailing ends of the document in the conveying direction are reversed by the document reversing means before and after the reversal of the document in the document conveying direction; An automatic document feeder comprising: a determination unit configured to determine that a document is transported abnormally when a length detection result before and after the reverse rotation of the document differs by a predetermined amount or more. 2. The method according to claim 1, wherein the determining unit determines that the document is transported abnormally when the result of the detection by the detecting unit is shorter than the document length before the document reverse rotation by a predetermined length or more. 2. The automatic document feeder according to claim 1, wherein: 3. The automatic document feeder according to claim 1, wherein a feed of a subsequent document to the image reading position is prohibited based on a determination that the determination unit determines that the document is transported abnormally. . 4. The automatic document feeder according to claim 1, wherein said detecting means is arranged in a path of said conveying means.