JPH112931A - Automatic document feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device itself without needing a long document carrying path for detecting the length of a document even in the different size coexisting mode of the documents. SOLUTION: This device is provided with the mode that the different-size documents coexist. Besides, it is provided with a regist sensor S2 detecting the leading edge and the trailing edge of the document in this mode, a lead sensor S3 arranged on the downstream side of the sensor S2 so as to detect the leading edge of the document and a document retreat path 41 on a more upstream side than a document read part. In the above mentioned mode, a carrying roller 22 is normally rotated and the document is carried from the leading edge thereof. After the trailing edge of the document is detected by the sensor S2, the roller 22 is reversely rotated until the leading edge part of the document is positioned on the more upstream side than the document read part. Then, the trailing edge side of the document is fed in the path 41.

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 used for an image reading apparatus such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, for example, an automatic document feeder installed on a copying machine main body automatically sends out originals placed on a paper feed tray one by one to a reading means on the copying machine main body. In general, a configuration is adopted in which an original is read by an optical system in a copying machine main body and then conveyed to a paper discharge unit (a similar technique is disclosed in Japanese Patent Application Laid-Open No. Hei 8-133551).

Prior to reading the original sent from the paper feed tray, it is necessary to inform the copier body of the information on the size of the original in advance. A plurality of sensors are arranged in the transport direction, and when a document is placed, the length of the document is detected by turning on / off the detection sensor.

However, in the above-mentioned detecting means, when originals of different sizes are mixedly placed on the paper feed tray, the detection sensor always detects the largest original among the originals. There was a problem that it was not possible to obtain sufficient size information.

Therefore, conventionally, a detection sensor is arranged on a conveyance path from a paper feed tray to a document reading section facing the reading means of the copying machine main body, and the size of the document sent one by one from the paper feed tray is set. Is detected on the transport path before the image is read.

[0006]

However, in the method of detecting the document size in the transport path as described above, a long transport path is required to detect the maximum size document (for example, an A3-size portrait document). Therefore, there is a problem that the automatic document feeder itself becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic document feeder capable of reliably detecting a document size before reading an image on a short conveyance path without increasing the size of the apparatus itself.

[0008]

According to an aspect of the present invention, there is provided an automatic document feeder, comprising: a document feeding unit, a document reading unit, a document discharging unit, And a transport roller that can rotate forward and reverse to transport the original along the original transport path, and sequentially feeds the originals stacked on the original feeder to the original reader. An automatic document feeder that scans the original surface and then discharges the original to the original discharge section is equipped with a mode to mix documents of different sizes and detects the leading and trailing edges of the document in this mode. First detecting means, a second detecting means disposed downstream of the first detecting means for detecting the leading edge of the document, and a document retreat path upstream of the document reading section. In the mode, the transport roller is rotated forward to feed the original. After the trailing edge of the document is detected by the first detection unit, the transport roller is rotated backward until the leading edge of the document is located upstream of the document reading unit, and the trailing edge of the document is Is fed into the document evacuation path.

According to a second aspect of the present invention, in the automatic document feeder according to the present invention, the document evacuation path is provided between a document feeding section and a document discharging section located below the document feeding section. Features.

According to a third aspect of the present invention, there is provided the automatic document feeder according to the present invention, wherein the document retreat path is provided branching from the document transport path, and switching to the document transport path is performed by a flapper. .

According to a fourth aspect of the present invention, in the automatic document feeder according to the present invention, the original is conveyed in the reverse direction based on a detection signal when the first detecting means detects the rear end of the original. While the rear end is fed into the document evacuation path, the document is conveyed again to the document reading section based on a detection signal when the second detecting means detects the front end of the document when the document is conveyed in the reverse direction. Is read.

Further, in the automatic document feeder according to the present invention, when the document is fed from the document feeder toward the document reader, the first detecting means detects the trailing edge of the document. Before detecting the document, when the second detecting means has already detected the leading end of the document, the document is conveyed in the reverse direction and sent to the document evacuation path.

[0013]

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. FIG. 1 is an overall schematic view of an automatic document feeder according to this embodiment, and FIG. 2 is an enlarged view of a main part.

The automatic document feeder 1 according to this embodiment has
A paper feed tray 2 on which a document is placed, a document take-out means 4 provided in the vicinity of a paper feed port 3, and a paper feed from the paper feed port 3 to a document reading section facing the document reading means 5 of the copying machine main body H. Paper path 6
A registration roller 7 provided in the middle of the paper feed path 6 for aligning the leading edge of the original; a conveying unit 8 for conveying the aligned original to the original reading unit; A document discharge unit 9 for discharging a document, and a document reversing unit 10 provided between the document reading unit and the document discharge unit 9, and a document placed on the paper feed tray 2 is read by the document reading unit. , And the original is read to the original discharge unit 9 after reading the surface of the original, or the original is turned over after reading the original.
At 0, switch back is performed, and the sheet is again fed to the document reading unit by the transport unit 8 to read the back side.

The copying machine main body H includes a transparent glass 11 for reading an image by the document reading means 5 when the document is automatically fed.
And a platen 12 that is read when an original such as a book is placed
And

The paper feed tray 2 is disposed so as 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 width of the original is
3 is detected. 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 S1 is composed of, for example, a limit switch, an optical sensor, and the like. In the case of the normal mode in which the documents placed on the paper feed tray 2 are all the same size, the size detection of the document using the guide plate 13 and the size detection sensor S1 is performed, and In the case of a so-called heterogeneous mixed mode in which originals are mixed, the operation is performed based on a unit described later without using the guide plate 13 and the size detection sensor S1.

The document take-out means 4 is provided near the paper feed port 3 and is capable of displacing a document placed on the paper feed tray 2 in the thickness direction. An arm 15 rotatably supports the 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, and is moved from the machine position to the paper feed position by the operation of the paper feed clutch 17a.
The document feeder 2 rotates following the rotation of, and feeds out the document on the paper feed tray 2. The separation roller 31 is rotated by the paper supply clutch 17b that operates simultaneously with the reverse rotation of the paper supply inversion motor 18, and separates the original one by one from the separation pad and sends out the original to the feeding path 6.

A registration sensor S2 is disposed near the downstream side of the separation roller 16, and a registration roller 7 is disposed near the downstream side. The registration sensor S2 is
In the normal mode, the leading edge of the document is detected. In the heterogeneous mixed mode, the trailing edge is detected in addition to the leading edge detection. In the heterogeneous loading mode, the document size is determined by obtaining the document length from the leading and trailing edge signals of the document detected by the registration sensor S2. The registration roller 7
The driving roller 20 includes a driving roller 20 and a driven roller 21, and the driving roller 20 rotates at a predetermined timing by the normal rotation of the sheet reversing motor 18. The leading edge of the document is a registration roller 7
And the leading end is aligned, the drive roller 20 rotates after waiting for a predetermined time, and the document is sandwiched between the driven roller 21 and is conveyed to the paper feed path 6.

The conveying means 8 includes a conveying roller 22 for winding and conveying the original, and pinch rollers 23 and 24 arranged on the peripheral surface of the conveying roller 22.
The document is gripped between the pinch rollers 23 and 24 and sent to a document reading unit facing the document reading unit 5. The rotation direction of the transport roller 22 is switched by forward / reverse rotation of the pulse motor 25.

A read sensor S3 is provided upstream of the original reading section.
Is arranged. The read sensor S3 is used to detect the leading edge of the document in the normal mode, and based on the detection signal, stops the rotation of the transport roller 22 and waits for the document to be read. The leading end (the trailing end in the feed direction at the time of reverse feed) is also detected. The conveyance of the document is restarted by the reading start signal sent from the copying machine main body H side. When the document passes over the surface of the transparent glass 11, the document is read by the document reading means 5.

The document reversing section 10 is located downstream of the document reading section, and has an introduction guide 27, a pair of reversing rollers 28 disposed in the vicinity thereof, and a switchback provided behind the reversing rollers 28. And a road 29. A pinch roller 3 is provided at the entrance end and the exit end of the introduction guide 27, respectively.
Reference numerals 0 and 31 are provided to assist conveyance along the paper discharge path 32 and carry-in / discharge at the document reversing unit 10, and the pinch roller 31 also has a function as a reversal resist when reading both sides. The reversing roller 28 can be opened and closed by a solenoid 33 and can also be rotated forward and backward by the sheet reversing motor 18. 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 go and send it out. A reversing sensor S4 is arranged near the reversing roller 28.

The original discharge section 9 is disposed below the paper feed tray 2 and has a pair of upper and lower guides 35 continuous from the discharge port.
And a pair of discharge rollers 36 provided in the middle of the guide 35 and a discharge tray 37. The paper discharge roller 36 can be rotated forward and reverse by the pulse motor 25. In the vicinity of the discharge roller 36, a discharge sensor S
5 is disposed to detect the discharge of the document.

Around the transport roller 22, flappers 38 and 39 for switching the transport direction of the original are arranged near the entrance of the original reversing section 10 and near the entrance of the original discharge section 9, respectively. These flappers 38 and 39 can be switched by a solenoid 40, and the first flapper 38 feeds a document conveyed from a document reading unit to a paper discharge path 32.
And the document reversing section 10 and the second flapper 3
Reference numeral 9 switches to the document discharge section 9 and a path for conveying the document to the document reading section again.

In this embodiment, a document evacuation path 4 branched downward from the paper supply path 6 is provided in a paper supply path 6 between the registration roller 7 and a pinch roller 23 which is pressed against the conveyance roller 22.
1 is formed. The document evacuation path 41 is normally urged upward by a spring, and a guide plate that forms a curved evacuation path between the flapper 42 whose leading end projects into the paper supply path 6 and the lower surface of the flapper 42. 43. The flapper 42 is pushed downward when the document is conveyed thereon and sinks out of the paper supply path 6, while when there is no document, the tip of the flapper 42 projects into the paper supply path 6 and the evacuation path is opened. ing.

Next, automatic reading of a document by the automatic document feeder having the above configuration will be described with reference to the timing charts of FIGS. 3 to 6 and the flow chart of the document shown in FIGS. 7 to 10.

First, with reference to FIGS. 3, 4 and 7, a description will be given of one-sided reading in the normal mode when an original of the same size is placed on the paper feed tray 2. FIG. 3 and 7
As shown in (a), when a plurality of sheets G of the same size are set on the sheet feeding tray 2, the empty sensor is turned on to detect the sheet G, and at the same time, the sheet size is immediately detected by the size detection sensor S1. The document size is set for transmission on the copying machine main body H side. When the start button on the copying machine main body H side is turned on, the sheet feeding reversing motor 18 and the sheet feeding clutch 17a operate, and the arm 15 of the sheet feeding roller 14 is moved.
Is rotated, and the separation roller 16 and the paper feed roller 14 are rotated.
Is rotated to separate and send out the top document among the documents G set on the paper feed tray 2.

When the registration sensor S2 detects the leading edge of the document G, the rotation of the separation roller 16 is stopped after a lapse of time t1, and the leading edge of the document G is brought into contact with the registration roller 7 to perform alignment. After the alignment by the registration roller 7 is performed, t
After waiting for 2 hours, the registration roller 7 is rotated to feed the original G to the paper feed path 6. Document G after t3 hours
The pulse motor 2
5 is rotated forward to rotate the transport roller 22, and the transport roller 2 is rotated.
The document G is nipped and transported between the sheet 2 and the pinch rollers 23 and 24. At time t7 after the lead sensor S3 detects the leading end of the document G, the transport roller 22 stops and waits for scanning. As shown in FIG. 4, the pulse motor 25 is driven again by the reading start signal from the copying machine main body H, the conveying roller 22 is rotated, and the reading of the front side of the document G is started. The rotation speed of the transport roller 22 during reading is
It is controlled at a low reading speed lower than the transport speed before reading. As shown in FIG. 7B, when the leading end of the document G enters the document discharge section 9, the sheet discharge sensor S5 detects and detects the
The sheet is discharged onto a sheet discharge tray 37 by a sheet discharge roller 36 rotated by the driving of the pulse motor 25 in the same manner as in the case 2 FIG.
As shown in (c), the feeding of the next original G1 is started during the reading of the original, and the rotation of the pulse motor 25 is accelerated after a predetermined time from the completion of the reading to perform the high-speed ejection, and the predetermined time t
After nine, the mode is switched to decelerated sheet discharging again to complete the sheet discharging.

Next, double-sided reading in the normal mode will be described. In this case, the same control as that shown in FIG. 3 and FIG. 7A is performed until the leading edge of the document G is detected by the read sensor S3 and the conveyance roller 22 stops and waits for scanning before reading the document. Will be As shown in FIGS. 5 and 8A, after t11 time from the start of reading of the document G, the sheet reversing motor 18 is driven to rotate the reversing roller 28, and the solenoid 40 is turned on to turn on both flappers 38. , 3
9 is switched to form a path on the document reversing unit 10 side. When the leading end side of the document G is conveyed into the switchback path 29, the reversing sensor S4 detects. As shown in FIG. 8B, the entire document G whose front surface has been read is fed into the switchback path 29 by the high-speed conveyance of the conveyance roller 22 at time t8 after the read sensor S3 is turned off. The rear end of G is held between the reversing rollers 28. Next, the reversing roller 28 is rotated in the reverse direction so that the original G
Is switched back, and the original G is sent out with the rear end side as the head. At this time, as shown in FIG. 8C, the leading end of the document G abuts on the pressure contact portion between the pinch roller 31 and the conveyance roller 22 arranged near the exit, and the reversal registration is performed for t13. Further, as shown in FIG. 2, the leading end of the document G is regulated by the guide 44 formed so as to protrude from the flapper 38, so that contact with the transport roller 22 is avoided,
It does not hinder the resist at the tip. After the registration, the transport roller 22 rotates at a high speed and quickly transports the document G to the reading position. The leading edge of the original G is read sensor S
3 is detected, and after t16 hours, the transport roller 22 is stopped to wait for scanning. The back side of the original G is read by a reading start signal from the copying machine main body H, and FIG.
As shown in (d), the leading edge of the document G is transported again into the document reversing unit 10. As shown in FIG. 9E, when reading is completed, the entire document is again conveyed into the switchback path 29 of the document reversing unit 10 by high-speed conveyance. Thereafter, the solenoid 40 is turned off and both flappers 38 and 39 are turned off.
Is switched to form a path on the side of the document discharge unit 9, and as shown in FIG. 9F, the document G whose front and back are reversed by the document reversing unit 10 is transported by the transport roller 22 and the discharge roller The paper is discharged at a high speed by 36 and discharged onto a paper discharge tray 37 to complete. As described above, when reading both sides of the original G, the original G is turned over, and then the paper is discharged.
The order of the originals G stacked on the paper feed tray 2 and the order of the originals G stacked on the discharge tray 37 can be matched.

Next, a description will be given of document reading in a so-called mixed type mixed mode in which documents of different sizes are mixed on the paper feed tray 2 with reference to FIGS. 6 and 10. FIG. Even in the case of a mixed type, normal mode is used until the original G placed on the paper feed tray 2 is sent out by the separation roller 16, aligned by the registration roller 7, and then conveyed toward the original reading unit by the conveyance roller 22. The operation is the same as that of the first embodiment except that the size detection sensor S1 installed on the paper feed tray 2 does not detect the document size. That is, the registered original G is allowed to pass through without being stopped in front of the original reading unit.
As shown in FIG.
Send out on 7. At this time, the original G is not read. In the process in which the original G passes through the original reading unit, the registration sensor S2 starts counting from the detection of the leading end of the original G. When the registration sensor S2 detects the rear end of the original G, the registration sensor S2 determines the length of the original G by the counted number during that time. Detect and send it to the copier main body H side. After the registration sensor S2 detects the trailing edge of the document G, the rotation of the transport roller 22 is stopped after a lapse of time t4. At this time, the rear end of the original G is
As shown in (b), the flapper 42 of the document evacuation path 41
It is in the position that got over. Next, as shown in FIG. 10C, when the original G is conveyed in the reverse direction by reversing the conveying roller 22 at a high speed, the rear end of the original G is fed into the evacuation path 41 while being guided by the flapper 42. It is. The read sensor S3 detects the leading edge of the document G again by the reverse feeding of the document G, and when it is confirmed that the leading edge has come off the document reading unit 5, the transport roller 22 stops. Next, the document G is fed by rotating the transport roller 22 forward, and the apparatus stands by after the lead sensor S3 detects the leading end. Upon receiving a reading start signal from the copying machine main body H, the transport roller 22 rotates forward to read the original G. The process from the reading of the original G to the discharge of the original G onto the paper output tray 37 is the same as the one-sided reading in the normal mode shown in FIGS. 7B and 7C. On the other hand, the document reversing unit 10
When reading on both sides by sending to
After (c), the flow of the document G is shown in (a) of FIGS.
Since the flow is the same as the double-sided reading in the normal mode shown in (f), detailed description is omitted.

Note that, even in the case of a mixed type, if the trailing end of the original G is detected by the registration sensor S2 before the leading end of the original G is detected by the read sensor S3 in front of the original reading unit, the original The document can be read as it is in the normal mode without retreating G.

As described above, the document evacuation path is provided in the middle of the document conveyance path, and the length of the document is detected using this evacuation path in the heterogeneous mixed mode. It is not necessary to take a long path, and the size of the device can be reduced.

A document retreat path is provided between the document feeding section and the document discharge section located below the document rejection section, and is provided branching from the document conveyance path. The space on the tray can be used, and further compactness can be achieved, and the structure becomes simple.

[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 sheet feed timing chart during single-sided reading in a normal mode.

FIG. 4 is a timing chart of conveyance / discharge at the time of single-sided reading in a normal mode.

FIG. 5 is a timing chart of conveyance / discharge at the time of duplex reading in a normal mode.

FIG. 6 is a paper feed timing chart in a different mixed mode.

FIG. 7 is an explanatory diagram showing a flow of a document at the time of single-sided reading in a normal mode.

FIG. 8 is an explanatory diagram showing the flow of a document when reading a front side in a duplex reading mode.

FIG. 9 is an explanatory diagram showing the flow of a document when reading the back side in the duplex reading mode.

FIG. 10 is an explanatory diagram showing a flow of an original when feeding paper in a different-system mixed mode.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 automatic document feeder 2 paper feed tray 5 document reading means 6 paper feed path (document transport path) 9 document discharge section 10 document reversing section 22 transport roller 32 discharge path (document transport path) 41 document retracting section G document H Copying machine body S2 Registration sensor S3 Lead sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhito Watanabe 430-1, Kobayashi, Masuho-cho, Minamikoma-gun, Yamanashi Pref.

Claims (5)

[Claims] An original feeding unit, an original reading unit, an original discharging unit, an original conveying path connecting them, and a forward / reverse rotatable conveying roller for conveying the original along the original conveying path. An automatic document feeder that sequentially feeds the documents stacked on the document feeder to the document reading unit to read the document surface, and then discharges the document to the document discharge unit. In addition to a mode to mix documents of different sizes,
First detecting means for detecting a leading edge and a trailing edge of a document in the mode; second detecting means arranged downstream of the first detecting means for detecting a leading edge of the document; A document evacuation path is provided on the more upstream side, and the transport roller is rotated forward in the mode to transport the document from the leading edge. After the first detecting unit detects the trailing edge of the document, the leading edge of the document is An automatic document feeder, wherein the transport roller is rotated backward until a copy unit is located upstream of the document reading unit, and the trailing end of the document is fed into the document evacuation path. 2. The automatic document feeder according to claim 1, wherein the document evacuation path is provided between a document feeding unit and a document discharging unit located below the document feeding unit. 3. The automatic document feeder according to claim 1, wherein the document retreat path is provided branching from the document transport path, and switching to the document transport path is performed by a flapper. 4. A document is conveyed in the reverse direction based on a detection signal when the first detection means detects the rear end of the document, and the rear end of the document is sent to the document evacuation path while the reverse direction is set. 2. The document according to claim 1, wherein the document is read again by transporting the document to the document reading unit based on a detection signal when the second detection unit detects the leading edge of the document when the document is transported to the document. Automatic document feeder. 5. When the document is fed from the document feeder toward the document reader, the second detector detects the document before the first detector detects the trailing edge of the document. 5. The document reading apparatus according to claim 4, wherein the document is conveyed in the reverse direction and sent to the document evacuation path when the leading edge of the document has already been detected.