JP2000095357A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of surely preventing the duplicate feed irrespective of the size of paper sheets. SOLUTION: In this paper feeder provided with a hopper 3b to hold a surface of stacked and mounted paper sheets in a butting condition against a circumferential surface of a pick-up roller 5, the tightening degree of a winding wire of a torsion spring 8 connected to the hopper 3b can be operated from an outer part making use of the rotation of a cam 9 to be engaged with a hook 8b of the torsion spring 8, and the pressure between the pick-up roller 5 and the paper sheets is appropriately controlled corresponding to the fluctuation in the weight load on the hopper 3b different according to the size of the paper sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device in an image reading device such as an image scanner, for example.
In particular, the present invention relates to a sheet feeding device in which separation performance is adjusted even when the size of a document changes so that reliable double feed prevention can be obtained.

[0002]

2. Description of the Related Art An image reading apparatus such as an image scanner is provided with a paper feeding device for feeding a sheet set on a hopper to a line. This sheet feeder feeds out stacked sheets one by one from the top, and most of the sheet feeders have a double feed prevention mechanism in which two or more sheets are sent out by friction between overlapping sheets. A paper feeder having such a double feed prevention mechanism is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-286558.

FIG. 6 is a schematic view showing a main part of a conventional example.
The one disclosed in the above publication has almost the same configuration.

[0006] In FIG. 6, a hopper 5 for mounting and setting a sheet P such as a document to be read or various documents.
1 is disposed at the base end of the reading line, and a pickup roller 52 that rotates in contact with the surface of the uppermost sheet P is disposed. The hopper 51 is urged toward the pickup roller 52 by a spring 51a.
By pressing the surface of the sheet P against the peripheral surface of the pickup roller 52, only the uppermost sheet P can be fed out.

In the line on the output side of the hopper 51, for example, three-stage conveying rollers 53, 54 and 55 for feeding the paper P to the image reading position are arranged, and the paper P fed from the hopper 51 is nipped. And transport it downstream while pulling it out. A separation roller 56 and a retard roller 57 are provided between the hopper 51 and the first-stage transport roller 53 as a mechanism for preventing double feeding of the paper P.

The prevention of double feeding by the separation roller 56 and the retard roller 57 is widely known in the field of an image reading apparatus, a copying apparatus and the like.
Is formed by interposing a torque limiter 57b around a main shaft 57a rotated in a direction indicated by an arrow in the figure by a drive motor (not shown). That is, by providing such a torque limiter 57b, the pickup roller 52
When one sheet of paper P is fed out, the retard roller 57 receives the rotation torque of the separation roller 56 and
When the sheet P is double-fed and nipped, the retard roller 57 keeps rotating in the direction of the arrow and pushes the double-fed lower sheet P back to the hopper 51 side.

[0007]

The size of the original paper P to be placed on the hopper 51 is various. For example, the size of the original paper P is such that the maximum size is A3 size and the minimum size is B5 size or smaller. It is necessary to As described above, when the size of the sheet P is set to be the same, the weight applied to the hopper 51 is large when the size of the sheet P is the same, and the weight load is small when the size is small. On the other hand, the spring 5
Since the spring constant of 1a is fixed, when the size of the sheet P is large, the pressing force on the pickup roller 52 is weak because the weight load is large, and the pressing force is strong as the size of the sheet P is small.

As described above, even when the pressing force applied to the pickup roller 52 changes depending on the size of the sheet P, the sheet P itself cannot be fed unless a proper frictional force with the pickup roller 52 is obtained. For this reason,
Even when the largest size paper P is placed on the maximum number of hoppers 51, the spring constant of the spring 51a must be set so that the frictional force required for feeding between the paper P and the pickup roller 52 can be secured.

However, when the size of the paper P is large, the setting of the spring constant of the spring 51a as described above
Feeding using friction between the pickup roller 52 and the peripheral surface is possible, but when the size of the sheet P is small, the weight load is small, and the urging force of the spring 51a is too strong. Therefore, the pickup roller 5
2 also increases the reaction force against the sheet P, and a large frictional force acts not only on the uppermost sheet P but also on the sheet below the sheet P, so that multiple feeds of the sheets P are likely to occur.

[0010] Even if such a double feeding of the paper P occurs, it is prevented by the separation roller 56 and the retard roller 57 disposed in the immediate vicinity of the hopper 51, and the paper P overlapping below is retarded by the retard roller 57. Should push back. However, if the pressing force of the pickup roller 52 against the sheet P exceeds the return force of the retard roller 57 due to strong pressing by the spring 51a, the multi-fed sheet cannot be returned. For this reason, the lower-side sheet P that is being multi-fed is pressed in the sheet feeding direction by the pickup roller 52 and, at the same time, receives a reverse return force by the retard roller 57. Therefore, the paper P is jammed between the pickup roller 52 and the retard roller 57, and the paper P cannot be fed out.

As described above, the sheet P loaded on the hopper 51
Of the paper P using the frictional force between the paper P and the pickup roller 52, the strength of the spring 51a pressing the paper P against the pickup roller 52 via the hopper 51 is constant. Likely to be.

An object of the present invention is to provide a sheet feeding device capable of reliably preventing double feeding regardless of the size of a sheet.

[0013]

According to a first aspect of the present invention, there is provided a paper feeder comprising: a pickup roller disposed at a start end of a line of paper to be fed; and a pickup roller disposed below the pickup roller and stacked on the upper surface thereof. A hopper which can be moved in a direction in which the surface of the uppermost layer abuts against the peripheral surface of the pickup roller, an elastic means for urging the hopper in the direction of the pickup roller, and an urging force capable of changing the urging force of the elastic means And adjusting means.

[0014]

According to the first aspect of the present invention, there is provided a pickup roller disposed at a start end of a line of a sheet to be fed, and a pickup roller disposed below the pickup roller and stacked and mounted on an upper surface thereof. A hopper that can be moved in a direction in which the surface of the upper layer abuts against the peripheral surface of the pickup roller, elastic means for urging the hopper in the direction of the pickup roller, and urging force adjustment that can change the urging force of the elastic means Means, the biasing force adjusting means can adjust the biasing force in the direction of the pickup roller according to the weight load of each sheet even if the size of the paper loaded on the hopper is various. Excessive pressing of the pickup roller is prevented, and an effect of preventing double feed regardless of the sheet size is provided.

According to a second aspect of the present invention, the hopper comprises:
One end facing the pickup roller is supported by a turning arm as a free end to turn up and down, and the biasing force adjusting means is interposed around a turning fulcrum of the arm. The hook at one end in the winding direction is engaged with the torsion spring connected to the arm, and the hook at the other end in the winding direction of the torsion spring is engaged, and the degree of tightening of the winding can be set by the rotation posture thereof. 2. The sheet feeding apparatus according to claim 1, further comprising a cam, and has an effect that double feed can be prevented by a simple operation merely by setting a rotation posture of the cam.

According to a third aspect of the present invention, in the paper feeder according to the second aspect, the cam is fixed to an adjustment shaft connected to an adjustment dial facing the outside of the paper feeder. Has the effect that the setting of the pressing force according to the type of paper can be easily performed only by operating the adjustment dial.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an image scanner including the sheet feeding device of the present invention.

In FIG. 1, an image scanner is provided with a housing 1 provided with an operation section 1a standing upright on the right side as viewed from the front, and a sub-housing 2 located on the left side of the operation section 1a and connected to open and close vertically. And a paper feed unit 3 for mounting a document such as a sheet on the front side of the housing 1 and below the sub-housing 2. The housing 1 and the sub-housing 2 are provided with a paper transport mechanism and an image reading device using an optical system. After reading an image from the paper fed from the paper feeding unit 3, a collection tray 2 a formed on the upper surface of the sub-housing 2 is provided.
The paper is ejected.

The paper feed unit 3 includes a frame 3a fixed to the housing 1 and a hopper 3b included in the frame 3a for mounting paper. The hopper 3b has a size corresponding to the size of the paper. And a pair of side guides 3c for changing the distance between them. The hopper 3b is rotatably pivoted at both ends on the distal end side to the frame 3a, and is rotatable in a vertical direction with the base end side as a free end. In other words, the frame 3a is kept in the fixed position shown in FIG. 1 with respect to the housing 1, but the hopper 3b is moved with respect to the housing 1 so that the base end thereof can freely move up and down. Assembled.

FIG. 2 is a longitudinal sectional view showing a main part of the sheet feeding device, and FIG. 3 is a plan view showing a main part of FIG.

Two arms 4 are rotatably mounted around a support shaft 1b fixed in the housing 1, and the bottoms of the bases of the hopper 3b are mounted on the ends of these arms 4. The supporting roller 4a is rotatably mounted. On the other hand, the tip of the hopper 3b is connected to the frame 3a via a pin 3d so as to be freely rotatable in the vertical direction. Therefore, when the arm 4 is rotated from the position indicated by the alternate long and short dash line in FIG. 2 to the position indicated by the solid line, the supporting roller 4a receiving the base end of the hopper 3b lifts the hopper 3b while rotating. When the arm 4 is turned counterclockwise in FIG. 2, the base end side of the hopper 3b is lowered, and the posture of the hopper 3b is set to the position indicated by the one-dot chain line in FIG.

In the sub-housing 2, a pickup roller 5 is disposed at a position covering the upper surface on the base end side of the hopper 3b, and a separation roller 6 is provided at a position slightly away from the hopper 3b. The pickup roller 5 and the separation roller 6 are disposed one by one at the center in the width direction of the hopper 3b, and the drive shaft 6a passing through the separation roller 6 is connected to the output shaft of a drive motor (not shown). . A drive system is connected between the separation roller 6 and the pickup roller 5 by, for example, a gear train.
And the pickup roller 5 rotates at the same peripheral speed.

Further, a hopper 3b is provided below the separation roller 6.
The retard roller 7 for preventing double feed is disposed below the pass line of the paper fed from the printer. The retard roller 7 is provided with a torque limiter. As is well known in the art, when the torque is below the critical set torque of the torque limiter, that is, when there is a multi-feed of paper, the retard roller 7 pushes the paper back to the hopper 3b. The rotation is continued, and when a load equal to or greater than the critical set torque is applied without the double feed of the paper, the paper rotates in the reverse direction in the paper feeding direction.

Here, the hopper 3b is provided on the support shaft 1 so that the uppermost layer of the paper loaded thereon comes into contact with the pickup roller 5 and is fed out by the frictional force.
The torsion spring 8 is interposed between the arm b and the arm 4. The torsion spring 8 utilizes a torsion coil spring.

As shown in FIG. 2, the torsion spring 8 has two hooks 8a and 8b projecting tangentially from the circumferential surface of the helical winding at both ends in the winding direction. 8a is provided in the arm 4 in the engagement hole 4b.
And the hook 8b at the other end is a free end.
A cam 9 for adjusting the elastic biasing force of the torsion spring 8 is arranged in contact with the hook 8b at the free end.

The cam 9 is fixed to an adjusting shaft 10 extending in the width direction of the housing 1. An adjusting dial 10a is attached to one end of the adjusting shaft 10 to face the side surface of the housing 1 as shown in FIG. Not. As shown in FIG. 2, the outer periphery of the cam 9 is a substantially elliptical arc surface eccentric with respect to the adjustment shaft 10, and the hook 8 b is connected to the torsion spring 8.
Press in the direction of tightening in the winding direction. Then, by turning the adjustment dial 10a, the position of the peripheral surface of the cam 9 which abuts on the hook 8b is changed, whereby the degree of tightening of the torsion spring 8 in the winding direction can be adjusted.

On the other hand, the arc by the torsion spring 8
As shown in FIG. 3, a drive motor 41 is provided as a drive mechanism for pushing down the arm 4 in response to the upward rotation of the arm 4. A transmission shaft 4 having an axis parallel to the support shaft 1b is provided on the output shaft of the drive motor 41 via a gear train 41a.
2, and a disk-shaped flange 43 is attached to both ends of the transmission shaft 42 in the axial direction. Two flanges 4
As shown in FIG. 3, the arm 3 faces each of the arms 4, and a boss 43 a which abuts on the upper surface of the arm 4 is protruded from the vicinity of the outer periphery of the flange 43 due to the rotation posture of the flange 43.

FIG. 4 is a schematic diagram showing the relationship between the position of the boss and the setting of the posture of the arm. In FIG.
Is separated from the upper surface of the arm 4. Therefore, the arm 4 is not restrained downward, and the arm 4 is rotated clockwise around the support shaft 1b by the urging force of the torsion spring 8, and the upper surface of the base end of the hopper 3b is picked up by the pickup roller 5.
The closest to you. On the other hand, when the flange 43 is rotated by the drive motor 41, the boss 43a comes into contact with the upper surface of the arm 4, and the arm 4 is pushed downward by the boss 43a. When the boss 43a is located at the lowest position as shown in FIG. 4B, the arm 4 assumes a substantially horizontal posture, and the hopper 3b assumes an inclined posture indicated by a dashed line shown in FIG. .

FIG. 5 is a schematic view showing the adjustment of the biasing force depending on the posture of the cam. In FIG. 7A, the peripheral surface of the cam 9 closest to the center of the support shaft 1b abuts on the hook 8b, and the degree of tightening of the hook 8b in the winding direction is minimal. The power is weak. FIG. 3B shows a state in which the adjustment shaft 10 is rotated clockwise by about 45 °, and the biasing force of the torsion spring 8 is set to an intermediate value. Then, as shown in FIG. 4A, for example, when the adjusting shaft 10 is further rotated by about 45 °, the peripheral surface of the cam 9 farthest from the center of the support shaft 1b abuts on the hook 8b and the torsion spring 8 The biasing force is set to the maximum.

As described above, by rotating the adjusting shaft 10, the amount of bias of the torsion spring 8 can be changed steplessly, and the base end side is received by the arm 4 by the support roller 4a. Pressing force of the hopper 3b on the pickup roller 5 side can be adjusted.

In the above arrangement, when the pickup roller 5 and the separation roller 6 are driven to rotate, the uppermost sheet mounted on the hopper 3b is fed out by friction with the pickup roller 5, as in the prior art. . Then, the separation roller 6 and the retard roller 7 form a pair, and as described above, the transport of the paper or the pushback of the double feed is performed by the function of the torque limiter.

Here, the hopper 3b of the sheet feeding unit 3
As described above, the load varies depending on the size of the sheet. That is, if the pressing force of the sheet against the pickup roller 5 is too large, not only the sheet is easily fed out in a multi-feed state, but also the function of returning the double-feed sheet by the retard roller 7 is impaired.

On the other hand, in the present invention, the adjustment dial 10
By rotating a, the posture of the cam 9 changes, and as shown in FIG. 5, the biasing force of the torsion spring 8 can be changed. The urging force of the torsion spring 8 acts in a direction to rotate the tip of the arm 4 upward in FIG. 2, so that the pressing force between the paper on the hopper 3b and the pickup roller 5 is adjusted. You can do it.

For example, when the size of the sheet is large, the load on the hopper 3b increases, and the force for pushing the hopper 3b around the pin 3d is strong. Therefore, in order to urge the hopper 3b upward against this pressing force to compensate the pressing force to the pickup roller 5, the cam 9 is set to the posture shown in FIG. I do. As a result, even if the load on the sheet is large, the urging force of the torsion spring 8 is transmitted to the hopper 3b via the arm 4, and the sheet P on the hopper 3b is pressed against the pickup roller 5 with an appropriate pressing force. be able to.

When the size of the paper is small and the load on the paper is light, the urging force of the torsion spring 8 can be reduced by turning the adjustment dial 10a so that the cam 9 shown in FIG. . Therefore, when switching from large-size paper to image reading of small paper, the biasing force becomes excessive when the posture of the cam 9 remains as shown in FIG. It is possible to switch to an urging force that matches the load to be loaded.

As described above, since the urging force of the torsion spring 8 can be increased or decreased according to the size of the paper placed on the hopper 3b, the contact pressure between the pickup roller 5 and the paper can be appropriately adjusted, and the multi-feeding by the pickup roller 5 can be performed. Effectively prevented. If the biasing force of the torsion spring 8 is made appropriate, the pressing reaction force from the pickup roller 5 can be suppressed to a level that does not interfere with the sheet returning force of the retard roller 7. Therefore,
Even if double feeding occurs due to the influence of the type of paper or humidity, only the upper sheet at the time of double feeding is fed out by the separation roller 6, and the lower sheet is quickly returned to the hopper 3 b side by the retard roller 7. . As a result, jamming of multi-feed paper is not caused between the pickup roller 5 and the retard roller 7, and efficient image reading can be performed without causing trouble in paper feeding.

[0037]

According to the first aspect of the present invention, even if the weight load on the hopper changes variously depending on the size of the paper,
Since the pressing force applied to the sheet from the pickup roller can be appropriately set by the urging force adjusting means, it is possible to reliably prevent the double feed of the sheet, which tends to occur particularly when switching to the small size sheet. In addition, in the case where a separation roller and a retard roller for preventing double feed are provided downstream of the pickup roller, the paper returned by the retard roller can be promptly received by the hopper side, and the occurrence of paper jam is effectively suppressed. Can be

According to the second aspect of the present invention, since double feed can be prevented by a simple operation merely by setting the rotational position of the cam, the apparatus configuration is simplified without including a complicated mechanism and maintenance and inspection are performed. Will also be easier.

According to the third aspect of the invention, the pressing force can be set according to the type of paper only by operating the adjustment dial from the outside. Therefore, when frequently using paper of different paper quality, the setting can be changed quickly. And work efficiency is increased.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an image scanner including a sheet feeding device of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of the sheet feeding device.

FIG. 3 is a plan view showing a main part of FIG. 2;

FIG. 4 is a schematic diagram showing the relationship between the position of a boss and the setting of the posture of an arm.

FIG. 5 is a schematic diagram showing adjustment of a biasing force according to a posture of a cam.

FIG. 6 is a schematic view showing a main part of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 1a Operation part 1b Support shaft 2 Subhousing 2a Collection tray 3 Paper feed unit 3a Frame 3b Hopper 3c Side guide 3d Pin 4 Arm 4a Support roller 4b Engagement hole 5 Pickup roller 6 Separation roller 6a Drive shaft 7 Retard roller Reference Signs List 8 torsion spring 8a, 8b hook 9 cam 10 adjustment shaft 10a adjustment dial 41 drive motor 41a gear train 42 transmission shaft 43 flange 43a boss

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F343 FA03 FB01 FC01 GA01 GB01 GC01 GD01 JD02 JD09 JD22 JD34 JD37 KB04 KB20 LA03 MA03 MA14 MA22

Claims (3)

[Claims] A pickup roller disposed at a starting end of a line of a sheet to be fed; and a top surface of a sheet disposed below the pickup roller and stacked and mounted on an upper surface of the pickup roller. A sheet feeder comprising: a hopper movable in a contacting direction; elastic means for urging the hopper toward the pickup roller; and urging force adjusting means capable of changing the urging force of the elastic means. 2. The hopper is supported by an arm for a rotation operation as a free end vertically rotating at one end side facing the pickup roller, and the biasing force adjusting means includes: The hook at one end in the winding direction, which is interposed around the rotation fulcrum, is engaged with the torsion spring connected to the arm and the hook at the other end in the winding direction of the torsion spring, and is wound by the rotation posture. 2. The paper feeding apparatus according to claim 1, further comprising a cam capable of setting a degree of tightening of the line. 3. The apparatus according to claim 2, wherein the cam is fixed to an adjustment shaft connected to an adjustment dial facing the outside of the sheet feeding device.
Paper feeder as described.