JPH0710394A - Automatic document feeding device - Google Patents

Abstract

PURPOSE:To prevent any stain on a document in feeding from occurring, in a device which assists the feeding power of a feed roller by dint of pushing pressure of the document through a pressing member. CONSTITUTION:A pressing means 13 assisting the feeding power of a feeding means 5 after pressing a document bundle 2 loaded to this feeding means 5 is made shiftable so as to be situated in a first position to be set for loading a document on a loading means, a document pressing position pressing the document and a second position capable of releasing 'pressure' of the pressing means 13. With this constitution, any stain on the document in time of feeding the cat bundle 2 is preventable, while such a possibility that the discharged document 5 might be refed by the feed roller 5 is prevented from occurring.

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 provided in an image forming apparatus such as a copying machine, a printer or a facsimile.

[0002]

2. Description of the Related Art Some image forming apparatuses such as copiers, printers and facsimiles are provided with an automatic document feeder for automatically feeding a document to an image reading section of the image forming apparatus body. FIG. 13 shows the overall structure of a conventional automatic document feeder provided in a copying machine.

The automatic document feeder feeds a plurality of documents 2 set on a document table (document tray) 1 from the lowest document, and a platen glass (image reading section) of the copying machine body 3 is fed. It is conveyed to a predetermined position on 4 and set.

At this time, a cylindrical paper feed roller 5 installed under the document table 1 feeds a plurality of documents 2 set on the document table 1 in order from the lowest document to the separation belt 06. It is sent between the rollers 07. The original 2 sent between the separation belt 06 and the feed roller 07 is separated into only the lowest original and sent to the nip portion of the registration roller pair 08 whose rotation is stopped, and the skewed state is corrected.

After that, the registration roller pair 08 rotates,
The original 2 whose skewed state has been corrected is sent between the platen glass 4 and the conveyor belt 09. The original 2 fed between the platen glass 4 and the conveyor belt 09 is conveyed to a predetermined position on the platen glass 4 by the conveyor belt 09 moving in the arrow A direction.

In this way, when the original 2 is set at a predetermined position on the platen glass 4, the optical system (not shown) in the copying machine main body 3 scans the original 2.

The original 2 whose image has been read by the optical system is returned from the platen glass 4 to the original table 1. At this time, the document 2 on the platen glass 4 is moved by the conveyor belt 9 moving in the direction of the arrow B to the reverse roller 10
Be transported to.

Then, the original 2 is sent to the paper discharge roller pair 11 by the reversing roller 10 and is discharged onto the original table 1.

In this automatic document feeder, the leading ends of a plurality of documents 2 set on the document table 1 are fed by a paper feed roller 5.
Shutter member 12 that can be moved up and down installed downstream of
The position is regulated by. When the paper feed roller 5 sends out the document 2 on the document table 1, the shutter member 12 is retracted below the document table 1 as shown by phantom lines.

Further, the paper feed roller 5 is used for the document 2 on the document table 1.
When feeding the document, the document pressing member (weight) 13 retracted to the solid line position above the document table 1 descends as shown by the phantom line, and the document feed roller 5 rotates the document 2 by its own weight.
It is pressed against the outer peripheral surface of the paper and serves to assist the document feeding of the paper feed roller.

Further, when the document 2 whose image has been read is discharged to the document table 1, the trailing end of the discharged document rides on the trailing end of the document pressing member 13 to convey the final unprocessed document. At the same time, the bottom sheet of the processed document is prevented from being re-fed.

[0012]

However, in the above-mentioned conventional example, since the document pressing member 13 constantly presses the document stack against the sheet feeding roller 5 by its own weight, it has the following drawbacks.

(1) When a plurality of originals are conveyed by the original conveying device, when the nth original is driven by the paper feed roller 5, the n + 1th original is also pressed by the original pressing member. 1
Since it is pressed against the n-th original by 3, the conveying force is given by the frictional force between the n-th original and the separation belt 6
And the feed roller 7 are pressed.

Further, the nth document is the registration roller pair 8
When the n-th document is pulled out by the registration roller pair 8 even when the paper feed roller 5 is released from the driving state and is freely rotated in the paper feed direction, the n + 1th document is pressed by the document. Since pressure is applied between the member 13 and the paper feed roller 5, a conveyance force is applied by frictional force, and the member 13 and the feed roller 7 are pressed against each other. The same applies to the (n + 2) th original.

At this time, the (n + 1) th original document is pressed to the vicinity of the nip portion between the separation belt 6 and the feed roller 7. Therefore, when the n-th original is separated and passes through the nip portion between the separation belt 6 and the feed roller 7, the front surface (upper surface) of the n-th original is near the nip member whose rear surface (lower surface) is the (n + 1) th original. Rub against each other. At this time, if the printing of the original document is in a poorly fixed state, the toner or the like used for printing the nth original document is fixed on the back surface of the (n + 1) th original document, causing back stain. Particularly in the above case, the edge portion of the back surface of the (n + 1) th original becomes dirty, that is, so-called edge dirt. (2) In order to solve the problem in the preceding paragraph, after the document reaches the feed roller 7, the document pressing member 13 is returned to the initial state shown by the solid line in FIG. 13 in order to release the pressure of the document pressing member 13. If this happens, the processed document is discharged onto the document pressing member 13, so that the portion of the processed document that is on the end of the document pressing member 13 slips off the document pressing member 13 and becomes the unprocessed document. It will overlap. With this,
The document pressing member 13 cannot serve as a partition plate between the processed document and the unprocessed document, and when the final sheet of the unprocessed document is conveyed, the processed document is also fed and the paper feeding operation is started again. That is, so-called re-feeding occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic document feeder which prevents the occurrence of document stains in a device which assists the feeding force of a feeding roller by pressing a document by a pressing member. .

[0017]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and, as shown with reference to the drawings, a stacking unit (1) for stacking a document stack (2) and the document stack. Feeding means (5) for feeding the lowest document of (2), and pressing means (13) for pushing the document bundle (5) against the feeding means (5) to promote the feeding force. In an automatic document feeder having a separating means (13) for separating the fed originals (2) one by one, the pressing means (13) is moved to a position for pressing the original bundle (2). A first position (A) that is an initial position when the document (2) is loaded on the stacking unit (1), and the document is moved by the pressing unit (13). A document pressing position (C) that presses, and the vicinity of a position lower than the first position and above the document pressing position. And a second position is a position (B), characterized in that it moves in.

[0018]

Based on the above-mentioned structure, the pressing means (13) for pressing the document bundle (2) against the feeding means (5) moves the document (2) to the first position (A) for placing the document. Move to the original pressing position (C) to be pressed and to the second position (B) where pressure is not applied to the original slightly above the original pressing position where the pressure of the pressing means (13) against the original can be released. enable. At the time of stacking the originals, the pressing means (13) is largely lifted so that the user can easily place the originals on the stacking means (1).

When the feeding force of the feeding means (5) is insufficient, the pushing means (13) moves to the document pushing position (C) to increase the feeding force of the feeding means (5). , The second position (B) when the original (2) can be conveyed by its own weight
By moving the pressing means (13) to, the document bundle (2) is prevented from being pushed into the nip portion of the separating portion (6, 7) and causing edge contamination.

Since the pressing means (13) can take the second position (B) slightly above the original pressing position, even if the processed original is ejected onto the pressing means (13), the processed original is discharged. The end does not fall from the pressing means (13),
The pressing means (13) can maintain the function as a partition plate for the processed document and the unprocessed document.

The reference numerals in parentheses are shown for reference to the drawings and do not limit the structure of the present invention.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Since the entire structure of the automatic document feeder is the same as that of the apparatus shown in FIG. 13, the description of this embodiment will be different from that of FIG.

1 and 2 show the construction of the essential parts of an automatic document feeder according to the first embodiment of the present invention. FIG. 1 is a perspective view and FIG. 2 is a vertical side view.

As shown in FIG. 13, a document table (stacking means)
A plurality of originals 2 set on the original platen 1 under 1
A paper feed roller (feeding means) 5 for sequentially feeding the lowest document is rotatably installed.

A document pressing member (pressing means) 13 is rotatably supported above the sheet feeding roller 5 so as to be able to freely move the weight arms 14 and 14B so as to apply pressure to the document 2 by its own weight. Has been done. Weight arm 14A, 1
4B is rotatably supported by a weight arm 17 so as to be rotatable integrally, and the document pressing member 13 is vertically swung by a control unit such as a motor and a rotary solenoid. In addition, the shutter member 12 includes a weight arm 17
When the document pressing member 13 is vertically moved, the document pressing member 13 is rotated vertically.

The lift arms 15A and 15B are for moving the document pressing member 13 to the second position B (FIG. 10), and are installed inside the weight arms 14A and 14B, and the document pressing member 13 is placed on the lower side. It has a role to lift from.

The original document conveyed by the paper feed roller 5 is sent between a separation belt 6 as a separation unit and a feed roller 7, and is separated into only the lowermost original document. Separation sensor 16 installed immediately downstream of the separation belt 6 and the feed roller 7.
Is for detecting the separated original 2.

Next, the operation method will be described.

When the original document is placed on the original table 1, the original document pressing member 13 is lifted by the weight arm 14 so that the user can easily load the original document 2.

Below the document table 1 on the downstream side of the paper feed roller 5, a shutter member 12 for restricting the leading edge of the document set on the document stacking table is interlocked with a weight arm 14 and is movable up and down. is set up.

When the document feeding operation is started by inputting the document feeding start signal, the weight arm 14 and the lift arm 15 are rotated downward by the control means such as a motor as shown in FIGS. The document pressing member 13 is moved to the document pressing position. At this time, the groove 14a is formed so that the document pressing member 13 is placed on the document stack by its own weight. At the same time, the shutter member 12 moves downward and the original 2
Is released from the front end, and the document pressing member 13 is released.
Is pressed against the paper feed roller 5. The original 2 is conveyed to the separation unit by the rotation of the paper feed roller 5 in the direction of the arrow.

The original 2 separated only at the lowermost position by the separation belt 6 and the feed roller 7 is detected by a separation sensor 16 installed immediately after the separation section.

When a control unit (motor control circuit or the like) of the lift arm 15 receives a signal for detecting that the document 2 has reached the separation sensor 16, only the lift arm 15 moves upward as shown in FIGS. Is rotated to move the document pressing member 13 to the second position B, and the pressure applied to the document 2 is released. At this point, the driving force from the driving unit is released from the sheet feeding roller 5, and the sheet feeding roller 5 is freely rotated in the document conveying direction.

Thereafter, the original 2 is conveyed further downstream by the feed roller 7 and the registration roller 8. While the original 2 can be conveyed to the paper feed roller 5 by the pressure of its own weight, the original pressing member 13 is stopped at the second position B, and the originals are sequentially conveyed. If it does not go into the separation section (if the sensor 16 does not detect the document even after a lapse of a predetermined time after feeding), the lift arm 15 is rotated downward by the second motor or the like,
By moving the document pressing member 13 to the document pressing position C, the document feeding force of the sheet feeding roller 5 is increased, and the document feeding is continued. The second motor starts rotating by the count-up signal of the timer.

The discharged original document rides on the upper portion of the original document pressing member 13 to prevent the original document from being re-fed.
As shown in, the amount of upward movement of the document pressing member 13 is
Since the amount is the minimum amount necessary to release the pressure on the document, the end of the document discharged onto the document pressing member 13 can ride on the document pressing member 13. If the document pressing member 13 is returned to the first position here, the edge of the discharged document will fall from the document pressing member 13, and therefore the final sheet of the unprocessed document will be drawn into the paper feed roller section when being conveyed. As a result, re-feeding occurs, but with the above configuration, re-feeding can be prevented.

Further, as shown in FIG. 11, a stopper 2 which can be rotated downward by its own weight is attached to the front end of the document pressing member 13.
1 is provided, and even when the document pressing member 13 is lifted to the second position, the leading end of the document pressing member 13 is in contact with the unprocessed document stack placed on the paper feed tray 1 with a light pressure and is discharged. When the processed document does not reach the upper surface of the document pressing member 13, it is possible to prevent the processed document from being fed to the paper feed roller unit and to prevent re-feeding. it can.
Note that the stopper 21 has a stop member as shown in FIG. 12 so that when the document pressing member 13 is raised to the first position, the end portion is not lowered too much and the document introducing portion is not narrowed. <Other Embodiments> In FIG. 9, a control means 19 for independently controlling the shutter member 12 that regulates the leading end of the original stack when the originals are stacked is provided. When the control means 19 is operated, it moves up and down via a lever that rotates in the direction of the arrow.

Further, the weight arm 14 has a first position A shown by a solid line in FIG. 10 and a second position B shown by a broken line.
A control means 18 for controlling to rotate to a document pressing position C indicated by a chain double-dashed line is provided at an end of the support shaft 17. The shutter 12 is always lowered downward during document transportation, and the document pressing member 13 is moved to the first position A and the second position by rotating the weight arm 14 by the control means 18 for rotating the weight arm. It is possible to move to B and the original pressing position C, and it is possible to obtain the same effect as in the above embodiment.

[0038]

As described above, according to the present invention, the pressing means for pressing the stacked document stack against the feeding means to assist the feeding force of the feeding means is the document stacking means. When the document is operated so as to be positioned at the first position set for stacking on the document, the document pressing position for pressing the document, and the second position where the pressure of the pressing unit can be released, It is possible to prevent the original placed on the sheet being fed from being soiled and prevent the discharged original from being re-fed.

[Brief description of drawings]

FIG. 1 is a perspective view of a document pressing member portion (first position) of an automatic document feeder according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view of a document pressing member portion (first position).

FIG. 3 is a side view of a document pressing member and a paper feed roller unit, which are also at a document pressing position.

FIG. 4 is a side view of the document pressing member and the lift arm portion, which are also at the document pressing position.

FIG. 5 is a side view of the document pressing member and the feeding roller portion, which are also in the second position.

FIG. 6 is a side view of the document pressing member and the lift arm portion, which are also in the second position.

[FIG. 7] Similarly, a document ejection operation diagram

[Fig. 8] Similarly, a feeding start operation diagram of a document.

FIG. 9 is a perspective view of a shutter member portion and a document pressing member portion according to another embodiment of the present invention.

FIG. 10 is a side view of the same lift arm.

FIG. 11 is a side view of the document pressing member and the stopper portion at the second position.

FIG. 12 is a side view of the document pressing member and the stopper portion at the first position.

FIG. 13 is a vertical cross-sectional side view showing an example of an automatic document feeder to which a conventional document pressing member portion and the document pressing member portion of the present invention are applied.

[Description of Reference Signs] 1 original table (stacking means) 2 original stack and original 3 image forming apparatus 5 paper feed roller (feeding means 6 separation belt 7 feed roller 8 registration roller 11 discharge roller 12 shutter member 13 original document pressing member (pressing) 14) Weight arm 15 Lift arm (moving means) 17, 18 Control means A First position of original document pressing member B Second position of original document pressing member C Original document pressing position

Claims (1)

[Claims] 1. A stacking unit for stacking a stack of documents, a feeding unit for feeding the lowest document of the stack of documents, and a press for pushing the stack of documents against the feeding unit to promote a feeding force. An automatic document feeder having a means and a separating means for separating the fed originals one by one, the moving means moving the pressing means to a position for pressing the original stack, A first position, which is an initial position when the documents are stacked on the stacking device, a document pressing position that presses the documents, and a position lower than the first position and below the document pressing position. And a second position which is a position near the upper side,
An automatic document feeder, which is characterized in that it is moved to.