JPH10194473A - Automatic document feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a document separating property by governing pressure of copy calling force and separating force in correspondence with thickness (the number of documents) of a document bundle. SOLUTION: When no document is put between a pressure lever 30 and a calling roller 8, the pressure lever 30 makes contact with the calling roller 8, energizing force of a pressure spring 31 is strongly applied, and pressure force of an eccentric cam 41 for pressure governing of a separation belt 13 also comes to be in the maximum state. When a bundle of documents 2 pushes up the pressure lever 30, a pressure link 36 is revolved by energizing force of the pressure spring 31, and pressure force is decreased. As the document bundle between the pressure lever 30 and the calling roller 8 becomes thinner, the pressure lever 30 and the pressure link 36 return to their original states, and pressure force is increased. Accordingly, a lever 43 for rotation of the eccentric cam 41 is rotated, and the eccentric cam 41 returns to its original state where pressure force of a pressure spring 40 is the maximum.

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 in combination with an image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art FIG. 1 shows a conventionally known automatic document feeder (A).
FIG. 3 is a diagram illustrating a basic configuration of an RDF. As shown in the figure, the document feed path of this apparatus has a sheet feed / separation unit 1 on the left side in the figure, a reversing sheet discharge unit 2 on the right side, a document table 3 on the center upper side, and a lower side thereof. And a transport belt 5 for transporting the original below the original discharge unit 4. The document fed from the document table 3 by the sheet feed / separation unit 1 is fed to the transport belt 5 while turning,
The conveyor belt 5 is stopped at a predetermined position on the contact glass 7 on the image forming apparatus main body 6, and is conveyed to the right side in the figure by the conveying belt 5 after exposure by an unillustrated exposure unit in the image forming apparatus main body 6. The document passes through the reverse sheet discharging unit 2 and is discharged to the document discharging unit 4 below the document table 3.

As shown in an enlarged manner in FIG. 2, the paper feed / separation unit 1 includes a call roller 8, a holding lever 9, a document set detection filler 10, a document stopper 11, a separation belt driven roller 12, a separation belt 13, a separation belt The roller 14 includes a roller 14, a separation belt driving roller 15, a document set sensor 16, a pull-out driving roller 17, a pull-out driven roller 18, and the like. The operation of the paper feed / separation unit 1 will be described. First, the document bundle 20 is placed on the document table 3 with the image side up, and
Is set at a position where the leading end of the original abuts the original stopper 11 at the entrance of the original. The document bundle 20 set to a position where it abuts the document stopper 11 is the document set detecting filler 1.
The document set sensor 16 detects that the document has been set on the document table 3 by lifting the document 0. When the start button of the image forming operation is pressed on the image forming apparatus main body 6 side, the call roller 1, the separation roller 6, and the pull-out drive roller 17 rotate counterclockwise in the drawing. Is transported to a position where the leading end abuts on the separation belt 6, and the lowermost document is frictionally separated from the document bundle 20 by the separation belt 6 and the separation roller 7, and the separation roller 7, the pull-out drive roller 1
7. Conveyed by pull-out driven roller 18.

[0004]

In an automatic document feeder mounted on an image forming apparatus such as a copying machine, a document bundle 2 is provided.
In the case of the method of separating the original from the bottom sheet of 0, the sum of the pressing force for the original mass and the pressing force of the spring is constant in order to keep the original calling force constant considering the weight of the original bundle 20. Must be set to When the lowermost sheet is separated from the original bundle 20 in the above-described conventional automatic document feeder, the pressing lever 9 serving as a pressing lever is directly pressed by the spring 19 to secure the pressing force of the call roller 8. , The pressing force increases in proportion to the thickness of the document bundle 20, which is opposite to the condition originally required. In such a case, when the document bundle 20 is thick, the total pressing force exceeds the appropriate force, and rubbing between the documents occurs due to the pressing force between the documents, and as a result, the back surface of the document tends to be rubbed and stained. However, there is a problem that the calling force becomes excessive and the separation unit tends to be multi-fed. On the other hand, when the number of originals is one, the weight of the original is minimized and the spring pressing force is also minimized, so that there is a tendency that the calling force is insufficient.

In frictional separation of an original by winding the separation belt 13 around the separation roller 14 by a fixed angle, a spring (not shown in FIG. 1) for setting the tension of the separation belt 13 is generally used. Had a fixed pressure. In such a separation mechanism, double feed can be prevented by changing the tension of the separation belt in accordance with the thickness of the document bundle 20, but such a separation cannot be performed if the tension setting spring has a fixed pressure.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an automatic document feeder capable of improving the document separation property by adjusting the document calling force and the separation force in accordance with the thickness of the document bundle (the number of documents). With the goal.

[0007]

In order to achieve the above object, an automatic document feeder according to the present invention is arranged such that a document bundle comprising a plurality of documents is placed on one side of the document bundle. And a separating / transporting unit that separates and transports the lowermost originals of the original bundle one by one by being sandwiched between a call roller located at a position and a pressure lever rotatably supported on the other side. In the automatic feeder, a link mechanism for connecting these is interposed between the pressing lever and an urging unit that presses the pressing lever against the call roller, and the link mechanism includes: The pressing lever by the urging means is allowed to rotate in a direction away from the calling roller according to the thickness of the document bundle inserted between the pressing lever and the calling roller. Of the inserted document bundle Characterized in that is as thick as possible automatically pressure regulating As pressure applied by the pressing lever is reduced is.

According to a second aspect of the present invention, the pressure lever has a slit extending in a longitudinal direction thereof, and the link mechanism is slidably connected to the pressure lever in the slit. And a connection point on the other side that is connected to the urging means.

According to a third aspect of the present invention, a separation belt and a paper feed roller are provided on the document feed direction forward side of the call roller, and the separation belt is wound around the paper feed roller by a predetermined angle with tension. A pressurizing spring for changing the tension by changing one position of a roller around which the separation belt is wound, and a pressurizing spring; A pressure adjusting mechanism, such as an eccentric cam, for varying the biasing force, wherein the pressure adjusting mechanism works in conjunction with the link mechanism to increase the tension of the separation belt as the thickness of the document bundle increases, and to adjust the separation belt as the thickness decreases. It is characterized in that the pressure can be adjusted so as to reduce the tension of.

According to a fourth aspect of the present invention, the connecting point on the other side of the link mechanism is connected to the pressure adjusting mechanism, the urging means also serves as the pressure adjusting mechanism, and the thickness of the document bundle is reduced. The pressure can be adjusted so that the tension of the separation belt increases as the thickness increases, and the tension of the separation belt decreases as the thickness decreases.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the following, the same reference numerals are given to the same parts and elements as those in the related art, and the duplicate description will be omitted. FIG. 1 shows a pressing roller pressing mechanism employed in an embodiment of the automatic document feeder according to the present invention. This mechanism is also a mechanism in which the pressing lever 30 is pressed against the calling roller 8 by the force of the pressing spring 31 to obtain a conveying force.

The pressure lever 30 is pivotally supported on a rotating shaft 32 as shown by a solid line and a chain line in the drawing.
A pressure release solenoid 34 is connected to the end of a connection lever 33 extending substantially at a right angle from the rotation shaft 32. A slit 35 extending in the longitudinal direction is formed at the center of the pressure lever 30, and one end of a pressure link 36 is slidably connected thereto. The pressure link 36 is a member having a substantially downward L-shape. The pressure link 36 is pivotally supported at a bent portion as a rotation axis 37 as shown by a solid line and a dashed line in the figure, and is rightward from the rotation axis 37 in the figure. The end of the portion extending to the left is connected to the slit 35 of the pressure lever 30, and the end of the portion extending to the left in the drawing is connected to the pressure spring 31. The pressure release solenoid 34 is used to release the pressure lever 30 when setting a document.

In this mechanism, when a document is not sandwiched between the pressure lever 30 and the call roller 8 (the state shown by a solid line in the drawing), the tip of the pressure lever 30 is
, And the urging force of the pressure spring 31 is strongly applied. When a document is inserted between the pressure lever 30 and the call roller 8 and the pressure lever 30 is pushed up (indicated by a chain line in the figure). (Shown state), the pressure link 36 is rotated by the urging force of the pressure spring 31, and the side connected to the slit 35 moves along the slit 35, so that the pressing force is reduced. Further, as the thickness of the document bundle between the pressure lever 30 and the call roller 8 decreases, the pressure lever 30 approaches the state shown by the solid line, and the pressure link 36 also changes to the state shown by the solid line. Going back, the pressure is increasing.

That is, when the pressing force of the pressing lever 30 is compared between the position indicated by the solid line and the position indicated by the chain line in the drawing,
Since the point of action of the pressure link 36 is closer to the center of the pressure lever 30 at the position of the chain line, the pressing force is reduced. That is, when the thickness of the document bundle is large (the number of documents is large), the pressing force is reduced, and the pressing force is set in consideration of the document mass.

FIG. 2 shows a separation belt tension adjusting mechanism employed in an embodiment of the automatic document feeder according to the present invention. This mechanism also has a separation belt driven roller 1 as in the prior art.
2 is urged away from the separation belt driving roller 15 by a pressure spring 40 to apply tension to the separation belt 13, and the separation belt 13 is wound around the separation roller 14 by a fixed angle to perform frictional separation. Mechanism. Of course,
When comparing the frictional force μr between the separation roller 14 and the paper and the frictional force μB between the separation belt 13 and the paper, it is necessary that μr> μB. The separation force is determined by the tension of the separation belt 13. As described above, it is desirable to set the separation force to the minimum value within a range that does not cause multifeeding in consideration of the influence on the original, but if this minimum tension is set to a fixed value as in the past, the general number of originals, Depending on the type, it is easy to set an excessive tension.

Therefore, in this embodiment, a pressure spring 40 for urging the separation belt driven roller 12 away from the separation belt driving roller 15 in accordance with the number of documents (thickness of the document bundle).
Is varied so that it always approaches the optimum value. Therefore, a pressure adjusting eccentric cam 41 is used as a mounting base of the pressure spring 40, and the pressure of the pressure spring 40 is changed by rotating the pressure adjusting eccentric cam 41 so that the tension of the separation belt 13 can be adjusted. I have. FIG.
Is a state in which the pressing force is the maximum, and the pressing force is reduced when the eccentric cam 41 is rotated from the state of FIG.

However, the mechanism shown in FIGS. 3 and 4 alone cannot simultaneously and automatically adjust the pressure applied to the call roller 8 and the tension of the separation belt 13 in accordance with the thickness of the document bundle. In the apparatus according to the embodiment of the present invention, as shown in FIG. 5, the mechanisms shown in FIGS. 3 and 4 are connected to enable finer setting of the pressing force and the tension. Therefore, the eccentric cam rotation lever 43 is attached to the rotation shaft 42 of the eccentric cam 41, and this is connected by the pressing link 36 by the connecting link 44, and the pressing spring 31 directly attached to the pressing link 36 is eccentric. It is attached to a connection portion between the cam rotation lever 43 and the connection link 44.

In this way, the height position of the pressure lever 30 when the document is inserted and the eccentric cam 41 are linked. That is, when the document is not sandwiched between the pressure lever 30 and the call roller 8 (the state shown by a solid line in the drawing), the tip of the pressure lever 30 contacts the call roller 8 and the pressure spring 31 is attached. While the force is strongly applied, the eccentric cam 41 is also in the state where the pressing force is maximum as shown by the solid line. Then, when the document 21 is inserted between the pressure lever 30 and the call roller 8 and the pressure lever 30 is pushed up (the state shown by a chain line in the figure), the pressure link 36 is rotated by the urging force of the pressure spring 31. Then, the side connected to the slit 35 moves along the slit 35 to reduce the pressing force, and the eccentric cam rotation lever 43 rotates to the state shown by the dashed line with the rotation of the pressure link 36. , The pressing force is reduced. Further, as the thickness of the document bundle between the pressure lever 30 and the call roller 8 decreases, the pressure lever 30 approaches the state shown by the solid line, and the pressure link 36 also changes to the state shown by the solid line. Not only does the pressing force increase, the eccentric cam rotating lever 43 also rotates toward the state shown by the solid line as the pressing link 36 returns, but also the eccentric cam 41 moves the pressing spring 4.
The state returns to the original state where the pressing force of 0 is maximized.

[0019]

As described above, in the automatic document feeder according to the first and second aspects, the pressing force of the call roller for calling the document is automatically adjusted according to the thickness of the document bundle.
As a result, it is possible to reduce the rubbing stain on the back side of the original when the maximum number of originals are stacked, and it is possible to set an appropriate calling force, thereby reducing the occurrence of problems such as double feeding and non-feeding.

As described above, the automatic document feeder according to the second and third aspects has a mechanism for adjusting the pressure of the pressure spring of the separation belt by an eccentric cam or the like. The separation belt tension is adjusted to the optimal value according to the thickness of the document bundle by interlocking with the pressure adjustment mechanism of the call roller so that the separation belt pressure is large and the separation belt pressure is small when the separation belt is thin. There is an effect that it is possible to always keep close to

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic configuration of an automatic document feeder.

FIG. 2 is an enlarged view showing a sheet feed / separation unit of the apparatus of FIG.

FIG. 3 is a diagram showing a call roller pressurizing mechanism employed in an embodiment of the automatic document feeder according to the present invention.

FIG. 4 is a diagram showing a separation belt tension adjusting mechanism employed in an embodiment of the automatic document feeder according to the present invention.

FIG. 5 is a view showing an embodiment of an automatic document feeder according to the present invention.

[Explanation of symbols]

 8 Calling Roller 12 Separation Belt Follower Roller 13 Separation Belt 14 Separation Roller 15 Separation Belt Driving Roller 21 Original 30 Pressing Lever 31 Pressing Spring 32 Rotating Shaft of Pressing Lever 33 Connecting Lever 34 Solenoid for Depressurizing 35 Slit 36 Pressing Link 37 Rotation shaft 40 Pressure spring 41 Eccentric cam 42 Eccentric cam rotation shaft 43 Eccentric cam rotation lever 44 Connecting link

Claims (4)

[Claims] An original bundle composed of a plurality of originals is sandwiched between a call roller located on one side of the original bundle and a pressure lever rotatably supported on the other side. In an automatic document feeder having a separating / transporting means for separating and transporting the lowermost documents one by one, a pressing lever, and a bias for pressing the pressing lever against the call roller are provided. Between the means, interpose a link mechanism that connects them,
The urging means allows the link mechanism to rotate in a direction away from the call roller in accordance with a thickness of a document bundle inserted between the pressure lever and the call roller. The pressure on the pressure lever is reduced, and the pressure can be automatically adjusted so that the pressure applied by the pressure lever decreases as the thickness of the inserted document bundle increases. Automatic feeder. 2. The pressure lever has a slit along a longitudinal direction of the pressure lever, and the link mechanism is connected to the pressure lever slidably in the slit at one side of a connection point;
2. The automatic document feeder according to claim 1, wherein a pivot point is rotatably supported between a connection point on the other side connected to the urging means. 3. A separation belt and a paper feed roller are provided on the document feed direction forward side of the call-out roller, and the separation belt is wound around the paper feed roller by a predetermined angle with tension, thereby performing frictional separation of the document. A pressure spring for varying the tension by changing one position of a roller around which the separation belt is wound, and an eccentric cam for varying the biasing force of the pressure spring. The pressure adjusting mechanism is provided so that the tension of the separation belt increases as the thickness of the document bundle increases, and the tension of the separation belt decreases as the thickness of the document bundle decreases. 3. The automatic document feeder according to claim 1, wherein the pressure can be adjusted. 4. The pressure adjusting mechanism is connected to the other connecting point of the link mechanism, and the urging means also serves as the pressure adjusting mechanism. As the thickness of the document bundle increases, the tension of the separation belt increases. 4. The automatic document feeder according to claim 3, wherein the pressure can be adjusted so that the tension of the separation belt becomes smaller as the separation belt becomes thinner.