JP2002002977A - Sheet material feeding mechanism in image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet material feeding mechanism in an image processor capable of surely preventing the double feeding by separating a feeding roller from a sheet material after the sheet material is fed by the feeding roller. SOLUTION: This sheet material feeding mechanism comprises the feeding roller 1 for picking up the sheet material such as the stacked paper S or the like to feed the same to an image processing system, and a pair of separating roller 2 and retard roller 3 mounted at a downstream side of the feeding roller at an inlet of an image processing system for preventing the double feeding, and the feeding roller 1 is temporarily separated from the paper S after the paper S is nipped between the separating roller 2 and the retard roller 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus such as an image scanner for reading a document image or an image processing apparatus such as an image forming apparatus such as a copying machine. The present invention relates to a sheet material supply mechanism in an image processing apparatus.

[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 paper feeder picks up and feeds stacked papers one by one from the top, and most of the paper feeders have a double feed prevention mechanism in which two or more sheets are fed out by friction between overlapping sheets. is there. A paper feeder having such a double feed prevention mechanism is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-286558.

FIG. 5 is a schematic view of a conventional paper feed mechanism. The one disclosed in the above-mentioned publication has almost the same configuration.

In FIG. 5, a hopper 5 for mounting and setting a sheet S such as a document to be read or various documents is set.
1 is disposed at the base end of the reading line, and above the hopper 51, a supply roller 52 for picking up and feeding out the topmost sheet S is disposed. The hopper 51 is urged toward the supply roller 52 by a spring 51a, and presses the sheet S against the supply roller 52 so that only the uppermost sheet S can be fed out by friction with its peripheral surface. Also, paper S
The pressing force against the supply roller 52 is kept substantially constant by the spring 51a even if the thickness of the stack varies.

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 S to the image reading position are arranged, and the paper S 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 sheet S.

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 a motor in which a torque limiter 57b is interposed around a main shaft 57a rotated in a direction indicated by an arrow in the drawing by a drive motor (not shown). The main shaft 57a of the retard roller 57 is connected to a drive motor (not shown) shared with the separation roller 56, and is attached upward in the figure by a spring for setting a nip force with the separation roller 56. It is being rushed. Such a torque limiter 57
When one sheet S is fed from the supply roller 52, the retard roller 57 receives the rotation torque of the separation roller 56 and rotates in the transport direction of the sheet S. When two or more sheets S are multi-fed and nipped, the retard roller 57 keeps rotating in the direction of the arrow to move the multi-fed lower sheet S to the hopper 51.
Push back to the side.

[0007]

Since the supply roller 52 is always in contact with the paper S on the hopper 51,
The same state is maintained after the sheet S is fed to the separation roller 56 and the retard roller 57 side. Thus, the supply roller 5
2 is always in contact with the sheet S, the separation roller 56
And the retard roller 57 may reduce the function of preventing double feed. That is, when the supply roller 52 is always in contact with the sheet S, the range of the double feed prevention due to the relationship between the pressing force of the retard roller 57 and the slip torque is narrowed, and the function of the double feed prevention is impaired to some extent. I will. Therefore, it is not possible to optimize the prevention of the double feed of the sheet S, and there is an upper limit in the reliability of the prevention of the double feed of the sheet S.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet material supply mechanism in an image processing apparatus capable of reliably preventing double feeding by operating the supply roller so as to be separated from the sheet material after the supply of the sheet material by the supply roller. And

[0009]

According to the present invention, there is provided a supply roller which picks up a sheet material such as stacked paper and feeds the sheet material to an image processing system, and is disposed downstream of the supply roller at an entrance of the image processing system. A roller pair of a separation roller and a retard roller for preventing double feed, and the supply roller is temporarily separated from the sheet material after the sheet material is nipped between the separation roller and the retard roller. It is characterized by having comprised.

According to the present invention, there is provided a sheet material supply mechanism in an image processing apparatus capable of reliably preventing double feeding by operating the supply roller so as to separate from the sheet material after the supply of the sheet material by the supply roller. Can be.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to a first aspect of the present invention is directed to a supply roller that picks up a sheet material such as stacked paper and feeds the sheet material to an image processing system. A roller pair of a separation roller and a retard roller for preventing double feed to be arranged is provided, and the supply roller is temporarily separated from the sheet material after the sheet material is nipped between the separation roller and the retard roller. This is a sheet material supply mechanism in an image processing apparatus characterized by the fact that, by separating a supply roller from a sheet material, it is possible to widen a constraint condition for preventing a sheet material from being double-fed, so that the sheet material is multi-fed. It has the effect that it can be prevented more reliably.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a main part of a sheet supply mechanism of the present invention, FIG. 2 is a side view showing a state in which a holder is lifted and a supply roller is separated from a sheet, and FIG. 3 is a view excluding a retard roller. It is a schematic perspective view of the supply mechanism shown.

As shown in FIG. 1, a sheet supply mechanism in the present embodiment includes a supply roller 1, a separation roller 2,
It is constituted by a combination of retard rollers 3. These rollers 1, 2, 3 are arranged above a hopper (not shown) on which the paper S is mounted in the same arrangement as that shown in FIG. 5, and a plurality of rollers are provided downstream of the separation roller 2 and the retard roller 3. A sheet conveying roller (not shown) is disposed, and the sheet S is discharged out of the apparatus via a reading unit in the case of a scanner, for example.

The retard roller 3 has a built-in torque limiter as is well known in the art, and is normally driven to rotate in a direction opposite to the sheet feeding direction, and when one sheet S is nipped with the separation roller 2. It rotates in the paper feeding direction and has a function of feeding only the top sheet S when two or more sheets S are nipped and pushing the remaining multi-feed sheets back to the hopper side.

In FIG. 3, reference numeral 4 denotes a supply roller drive shaft connected to a motor (not shown). A separation roller 2 is rotatably arranged around the supply roller drive shaft 4. The separation roller 2 is connected to another motor (not shown) by a rotation drive system. The separation roller 2 is driven to rotate independently of the supply roller 1. The supply roller drive shaft 4 is rotatably attached to a base end of a holder 5 for holding the supply roller 1.

The holder 5 rotatably holds the supply roller 1 and interposes a gear train (not shown) between the supply roller 1 and the supply roller drive shaft 4 so that the supply roller drive shaft 4 rotates. It is transmitted to the supply roller 1. The supply roller 1 has a built-in one-way clutch 1a so that the supply roller 1 can rotate only in the direction in which the sheet S is fed, regardless of the rotation direction of the supply roller drive shaft 4.

On the other hand, a stopper lever 6 for restraining the attitude of the holder 5 is connected to the supply roller drive shaft 4. The stopper lever 6 is attached around the supply roller drive shaft 4 with a torque limiter 6a interposed therebetween. A proximal end of the stopper lever 6 is connected to a tension coil spring 7 so that the supply roller drive shaft 4 shown in FIGS. Are biased counterclockwise. The distal end of the stopper lever 6 can be engaged with a hook 5 a provided on the holder 5. Then, it is assumed that the set torque of the torque limiter 6 a built in the stopper lever 6 is set to be larger than the urging force of the coil spring 7.

Here, in FIG.
Is rotated by a motor in the direction indicated by the solid line in the figure, the rotation in the direction to feed the paper S is transmitted to the supply roller 1 via a gear train. At the same time, the stopper lever 6 attached to the supply roller drive shaft 4 via the torque limiter 6a rotates clockwise in FIG.
It rotates until it hits a stopper block 8 arranged near the holder 5. Therefore, the holder 5 restrained by the stopper lever 6 via the hook 5a rotates around the supply roller drive shaft 4 by its own weight including the supply roller 1, and the supply roller 1 is placed on the upper surface of the sheet S on the hopper. Then, the torque limiter 6a idles, and the supply roller drive shaft 4 continues to rotate to rotate the supply roller 1 in a direction to feed the paper S.

On the other hand, from the state of FIG.
Is rotated in the direction of the broken line in FIG.
The stopper lever 6 attached to the supply roller drive shaft 4 via the torque limiter 6a rotates counterclockwise in FIG. Thereby, the tip side of the stopper lever 6 pushes up the hook 5a, and the holder 5 rotates as shown in FIG. Thereby, the supply roller 1 is separated from the upper surface of the sheet S on the hopper. The rotation is also transmitted to the supply roller 1 when the supply roller drive shaft 4 is rotated in the reverse direction.
, There is no reverse rotation of the supply roller 1 and there is no operation of returning the sheet S to the hopper side.

In the above configuration, the supply roller 1 is
When the sheet S is in contact with the sheet S on the hopper, the supply roller drive shaft 4 rotates in the direction indicated by the solid line in FIG. . Thus, the sheet S is fed by the supply roller 1. When it is detected that the sheet S has been nipped by the separation roller 2 and the retard roller 3, the output shaft of the motor that rotates the supply roller drive shaft 4 is rotated in the reverse direction. The nip of the sheet S may be detected using, for example, a sensor of an optical system or a signal of the displacement of the separation roller 2 or the retard roller 3 depending on the thickness of the nip sheet S.

By the reverse rotation of the output shaft of the motor, the supply roller drive shaft 4 rotates in the direction shown by the broken line in FIG. 3, and the stopper lever 6 moves counterclockwise around the supply roller drive shaft 4 in FIG. Rotate clockwise.
Accordingly, the tip of the stopper lever 6 engages with the hook 5a to lift the holder 5 as shown in FIG. 2, and the supply roller 1 is separated from the upper surface of the sheet S on the hopper. As a result, the paper S nipped between the separation roller 2 and the retard roller 3 and the supply roller 1 become non-engaged, and the supply roller 1 does not participate in the prevention of the double feed by the separation roller 2 and the retard roller 3, so that the double feed can be prevented. It is performed more reliably. That is, the supply roller 1 feeds the paper S until the paper S is nipped, but after the nip, the supply roller 1 rises to eliminate the interference with the paper S.

FIG. 4 is an explanatory diagram showing whether the above-mentioned operation is effective in preventing double feed. FIG. 4A is a diagram showing a combination of a supply roller 1, a separation roller 2, and a retard roller 3;
FIG. 4B is a diagram illustrating a state in which multiple sheets are fed, and FIG. 4B is a diagram illustrating a relationship between a pressing force of the retard roller 3 and a slip torque thereof.

Here, P: pressing force of the retard roller 3,
N: pressing force of supply roller 1, μ: separation roller 2 and paper 2
1, μp: coefficient of friction between sheets 21 and 22, T: slip torque of retard roller 3, r: radius of retard roller 3, retard roller for preventing double feed The range in which the pressing force P of (3) should be satisfied is to satisfy the conditions of the following equations (1) and (2).

P> (T / r · μ) + (μp−μ) · N / μ (1) P> (T / r · μp) -2N (2) The double feed, paper separation and slip determined by the correlation between the pressing force P of the retard roller 3 and the slip torque T are the double feed area and the normal separation area shown in FIG. , Slip region. Therefore, if the normal separation area is expanded, more reliable double feed prevention can be achieved. In order to expand the normal separation region in this manner, N may be made to approach zero.

On the other hand, as described above, after the sheet S has been nipped by the separation roller 2 and the retard roller 3, FIG.
When the holder 5 is lifted so that the supply roller 1 is separated from the sheet S as described above, N = 0 can be set. Therefore, the normal separation area in FIG. 4B can be expanded, and the double feed can be reliably prevented.

[0027]

According to the present invention, since the supply roller is separated from the sheet material, the restricting condition for preventing the double feeding of the sheet material can be expanded, so that the double feeding of the sheet material can be more reliably prevented. .

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of a sheet material supply mechanism of the present invention.

FIG. 2 is a side view showing a state in which a holder is lifted and a supply roller is separated from a sheet.

FIG. 3 is a schematic perspective view of a supply mechanism excluding a retard roller.

FIG. 4A is a diagram illustrating a state in which two sheets are multi-fed by a combination of a supply roller, a separation roller, and a retard roller. FIG. 4B is a diagram illustrating a relationship between a pressing force of the retard roller and a slip torque thereof.

FIG. 5 is a schematic view of a conventional paper feed mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Supply roller 1a One-way clutch 2 Separation roller 3 Retard roller 4 Supply roller drive shaft 5 Holder 5a Hook 6 Stopper lever 6a Torque limiter 7 Coil spring 8 Stopper block S Paper

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Junichi Suematsu 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 3F343 FA02 FA03 FB01 FC01 GA01 GB01 GC01 GD01 JA19 JA20 JD09 JD33 JD40 LC11 MB13 MB14 MC19 MC22

Claims (1)

[Claims] 1. A supply roller for picking up a sheet material such as stacked paper and feeding it to an image processing system, and a separation for preventing double feed disposed downstream of the supply roller and at an entrance of the image processing system. A roller pair of a roller and a retard roller, wherein the supply roller is temporarily separated from the sheet material after the sheet material is nipped between the separation roller and the retard roller. A sheet material supply mechanism in the image processing apparatus.