JPH1120965A - Paper feeder - Google Patents

Abstract

(57) [Problem] To provide a paper feeder capable of ensuring that a separation roller rotates and preventing the occurrence of a non-feeding jam. A paper feed belt (or paper feed roller) is pressed against a separation roller, and paper entering a nip portion is separated and fed one by one. The separation roller 6 includes a torque limiter 8
And is driven in reverse rotation by the drive motor 11. When there is no paper in the nip portion, the separation roller 6
When there is a sheet in the nip, the separation roller 6 rotates in the reverse direction. The separation roller 6 has an elastic high friction portion 13.
And a guide portion 14 made of a rigid body.
By the action of 4, both the entraining property and the reversing property are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder used in an image forming apparatus such as a copying machine or a printer, or an automatic document feeder. The present invention relates to an improvement in a sheet feeding device that combines a separation roller and a separation roller.

[0002]

2. Description of the Related Art A sheet feeding means such as a sheet feeding belt or a sheet feeding roller is brought into contact with a separation roller having a built-in torque limiter with an appropriate pressing force to separate and feed the sheets called by the calling roller one by one. 2. Description of the Related Art A paper feeding type paper feeding apparatus is widely used in an image forming apparatus main body or an automatic document feeder attached thereto. In such a type of paper feeding device, when there is no paper in the nip portion between the paper feeding device and the separation roller, or when there is only one sheet, the separation roller rotates with the paper feeding device, while the nip portion When two or more sheets are inserted, there is a type in which the separation roller is reversed by the action of the torque limiter to loosen multi-feeding sheets. In addition, a driving force in the reverse direction is always applied to the separation roller via a torque limiter, and when there is no sheet in the nip portion between the sheet feeding unit and the separation roller, the separation roller rotates along with the sheet feeding unit. There is also a type in which a separation roller is reversed by the action of a torque limiter when one sheet enters the nip portion. In this case, even if the separation roller is reversed, the paper is fed by the paper feeding means.

[0003]

Among the above-mentioned paper feeders, in the latter type, that is, in the case where a driving force is added to a separation roller via a torque limiter, conventionally, the reliability of the rotation of the separation roller is reduced. There was a case that was missing. If the entrainment is not performed properly, there is a problem that a non-feeding jam is likely to occur.

[0004] An object of the present invention is to provide a sheet feeding device which ensures the rotation of the separation roller in consideration of the configuration of the separation roller and can prevent the occurrence of a non-feeding jam.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a paper feeding means such as a paper feeding belt or a paper feeding roller,
In a paper feeder provided with a separation roller driven in a reverse direction to a paper feeding direction via a torque limiter, the separation roller includes a high friction portion having a high friction coefficient and a guide having a lower friction coefficient than the high friction portion. This is solved by a first means having a portion. The above object is achieved by a paper feeding device according to a first means,
The high friction portion is disposed at a central portion in the axial direction of the separation roller, and the guide portion is solved by a second means disposed outside thereof. According to a second aspect of the present invention, in the paper feeding device, the high friction portion is formed of an elastic member such as sponge rubber, and the guide portion is formed of a third member formed of a rigid body such as resin or metal. Is done. The above issues are
In the paper feeding device of the third means, the outer peripheral surface of the high friction portion is solved by the fourth means which is set slightly higher than the outer peripheral surface of the guide portion. According to a fourth aspect of the present invention, in the paper feeding device of the fourth aspect, the protrusion amount of the outer peripheral surface of the high friction portion is:
When the high friction portion is compressed in a state where the separation roller is in contact with the sheet feeding means, the problem is solved by the fifth means which is set to be substantially flush with the outer peripheral surface of the guide portion.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a sheet feeding device to which the present invention is applied. This paper feeder is applied to an automatic document feeder, and is intended for the original 1 as paper. The sheet feeding device includes a pressing plate 2 for pressing the document 1 upward, a call roller 3, a guide plate 4, a sheet feeding belt 5 stretched between a pair of rollers, and a separation contacting the sheet feeding belt 5 with a predetermined pressure. Roller 6, paper feed belt 5 and separation roller 6
The transport rollers 7 on the downstream side of the nip portion are provided. Manuscript 1
Is pressed against the call roller 3 by the pressing plate 2. The original 1 is fed to the nip by the call roller 3. The document 1 separated into one sheet at the nip portion is transported by a transport roller 7 to a reading unit (not shown).

FIG. 2 is a schematic perspective view of a drive mechanism of the separation roller. The separation roller 6 is drivingly connected to one of a pair of drive pulleys 9 via a torque limiter 8. A drive belt 10 is stretched around the drive pulleys 9 and 9. Since the other drive pulley 9 is driven by the drive motor 11, the separation roller 6 is driven by the drive motor 11 in the direction of arrow B (reverse rotation direction) when there is no load. When the sheet is in contact with the sheet feeding belt 5 shown in FIG.

FIG. 3 is a perspective view showing an abutting state of a sheet feeding roller and a separation roller. In the example illustrated in FIG. 1, the nip portion is configured by bringing the sheet feeding belt 5 and the separation roller 6 into contact with each other.
As shown in (1), a paper feed roller 12 may be provided in place of the paper feed belt 5.

FIG. 4 is a front view showing an example of a separation roller used in the sheet feeding device of the present invention. The separation roller 6 is made of a rigid body having a low friction coefficient μ such as resin or metal as a base material, and an elastic member having a predetermined friction coefficient μ such as sponge rubber is wound around the axial stop portion at a predetermined width. Thus, the separation roller 6 is configured. Then, the elastic member is replaced with the high friction portion 13
And the rigid portion is a guide portion 14. High friction part 1
3 is higher than the outer peripheral surface of the guide portion 14 by Δh.

FIG. 5 is an explanatory view showing a state in which a paper feed belt or a paper feed roller contacts a separation roller. Guide section 1 for paper feed belt 5 (or paper feed roller 12) and separation roller 6
4 face each other with a gap of Δh, but by applying a predetermined separation pressure P between the paper feed belt 5 and the separation roller 6, the high friction portion 13 is deformed, and the paper feed belt 5 and the separation roller are separated. 6 comes in contact with the whole area in the width direction. In the figure, R1 indicates the reaction force of the guide portion 14, and R2 indicates the reaction force of the high friction portion 13.

FIG. 6 is a perspective view of a main part of the sheet feeding device according to the embodiment of the present invention. A paper feeding belt 5 is used as paper feeding means, and a separation roller 6 having a structure shown in FIG. 4 is used.
The radius of the separation roller 6 is R. The following is a description of the case where the document 1 is not in the high friction portion and the case where it is present. (1) When there is no original 1, μ1; friction coefficient between the feed belt 5 and the guide portion 14 (≒ 2 or more) μ2; friction coefficient between the feed belt 5 and the high friction portion 13 (≒ 2 or more) F1; The transfer force between the belt 5 and the guide unit 14 (μ1 × R
1) F2: Conveying force between the feed belt 5 and the high friction portion 13 (μ2 × R
2) When there is no original 1, the separation roller 6 rotates with the paper feed belt 5 by overcoming the torque T1 of the torque limiter 8. The torque at that time is T2 = R × (F1 + F
2). The relationship between T1 and T2 is T1 <T2. (2) When document 1 is present: μ0; coefficient of friction between document 1 (μ) μ3; coefficient of friction between belt 5 and document 1 μ4; coefficient of friction between guide portion 14 and document 1 μ5; high friction portion 13 and document 1 F3: conveying force between the original 1 and the guide section 14 (μ3 × R1) F4; conveying force between the original 1 and the high friction section 13 (μ4 × R1) Also, μ3 ≒ 1.5> μ5 ≒ 1.0> μ0 ≒
0.4≫μ4 ≒ 0.1. When the document 1 is present, the torque T3 acting on the separation roller 6 is T3 = R ×
(F3 + F4). Since the transport force of F3 becomes small, when T3 <T1, the separation roller 6 does not rotate,
It rotates in the direction B in FIG. Since the next document 1 does not enter due to this rotation, double feeding hardly occurs. Here, the guide portion 14 has a very low μ with respect to the document 1 and is hardly stained, so that μ with the paper feed belt 5 is stable, and the guide portion 14 has good adhesion, so that Is relatively μ
Is high. As a result, the separation belt 6 is stably rotated with respect to the paper feed belt 5, so that the document 1 easily enters the nip portion and almost no non-feeding jam occurs.

In the above-described embodiment, the sheet feeding means by the sheet feeding belt 5 and the sheet feeding roller 12 is brought into contact with the sheet feeding means, and the sheet is fed to the sheet feeding direction via the torque limiter 8. In the sheet feeding device provided with the separation roller 6 driven in the reverse rotation direction, the separation roller 6 has a high friction portion 13 having a high friction coefficient.
And a guide portion 14 having a lower coefficient of friction than the high friction portion 13, or the high friction portion 13 is disposed at the axial center of the separation roller 6, and the guide portion 14 is disposed outside the The friction portion 13 is formed of an elastic member such as sponge rubber, and the guide portion 14 is formed of a rigid body such as resin or metal, or the outer peripheral surface of the high friction portion 13 is set slightly higher than the outer peripheral surface of the guide portion 14. Alternatively, the projecting amount of the outer peripheral surface of the elastic member is set to be substantially flush with the outer peripheral surface of the guide portion 14 when the high friction portion 13 is compressed in a state where the separation roller 6 is in contact with the sheet feeding means. Therefore, the guide portion 14 of the paper feed belt 5 or the separation roller 6 which is in contact with the paper feed roller 12 is made of a rigid body, so that the paper (including the original) is hardly stained. 5. Good adhesion with paper feed roller 12 Ri property is stable. Therefore, the sheet can easily enter the nip portion composed of the sheet feeding belt 5 and the sheet feeding roller 12 and the separation roller 6, so that a non-feeding jam can be prevented. Further, when a sheet enters the nip portion, the friction roller between the guide portion 14 and the sheet has a small friction coefficient, so that the separation roller 6 is immediately reversed by the torque limiter. At this time, the entry of the next sheet is prevented by the high friction portion 13 of the separation roller 6, so that the occurrence of double feed is extremely reduced. Therefore, the reliability of the sheet feeding performance can be improved.

[0013]

According to the first to fifth aspects of the present invention, the guide portion of the paper feed belt or the separation roller that is in contact with the paper feed roller is made of a rigid body, and is formed of paper (including an original). Is less likely to adhere to the paper feed belt and the paper feed roller. Therefore, since the sheet can easily enter the nip portion formed by the sheet feeding belt and the sheet feeding roller and the separation roller, the non-feeding jam can be prevented. When a sheet enters the nip portion, the separation roller is immediately reversed by the torque limiter because the friction coefficient between the guide portion and the sheet is small.
At this time, the next sheet is prevented from entering by the high friction portion of the separation roller, so that the occurrence of double feed is extremely reduced. Therefore,
The reliability of the paper feeding performance can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sheet feeding device to which the present invention is applied.

FIG. 2 is a schematic perspective view of a driving mechanism of a separation roller.

FIG. 3 is a perspective view showing a contact state between a sheet feeding roller and a separation roller.

FIG. 4 is a front view showing an example of a separation roller used in the sheet feeding device of the present invention.

FIG. 5 is an explanatory diagram showing a state where a paper feed belt or a paper feed roller and a separation roller come into contact with each other.

FIG. 6 is a perspective view of a main part of the sheet feeding device according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 5 paper feed belt 6 separation roller 8 torque limiter 11 drive motor 12 paper feed roller 13 high friction part 14 guide part

Claims (5)

[Claims] 1. A paper feeder comprising a paper feed means comprising a paper feed belt or a paper feed roller, and a separation roller which comes into contact with the paper feed means and is driven in a direction reverse to the paper feed direction via a torque limiter. In the apparatus, the separation roller includes a high friction portion having a high friction coefficient and a guide portion having a lower friction coefficient than the high friction portion. 2. The sheet feeding device according to claim 1, wherein the high friction portion is disposed at an axially central portion of the separation roller, and the guide portion is disposed outside the separation roller. apparatus. 3. The paper feeding device according to claim 2, wherein the high friction portion is formed of an elastic member such as sponge rubber, and the guide portion is formed of a rigid body such as resin or metal. Paper feeder. 4. The sheet feeding device according to claim 3, wherein an outer peripheral surface of the high friction portion is set slightly higher than an outer peripheral surface of the guide portion. 5. The sheet feeding device according to claim 4, wherein the amount of protrusion of the outer peripheral surface of the high friction portion is such that the high friction portion is compressed in a state where the separation roller is in contact with the sheet feeding means. The sheet feeding device is set to be substantially flush with the outer peripheral surface of the guide portion.