JPH08295426A - Paper feeding device - Google Patents

Abstract

PURPOSE: To provide a paper feeding device of a simple constitution in which double feed of sheets can be securely prevented. CONSTITUTION: In a paper feeding device in which a separation member 20 is applied to a sector-shaped feed roller 1 for separating sheets between the feed roller 1 and the separation member 20 to be fed one by one, sleeves 11 of a smaller diameter than the feed roller 1 which are only a little extended in the rotary direction of the feed roller 1 are provided on both sides of the feed roller 1, and the sleeves 11 and the separation member 20 are applied to separate the sheets before the separation member 20 and the feed roller 1 are applied.

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 of an image forming apparatus such as a printer, a copying machine and a facsimile device using an electrophotographic system, and more particularly to a sheet feeding device using a fan-shaped sheet feeding roller.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic method, a sheet feeding device is used which separates sheets one by one from a sheet feeding cassette and feeds the sheets. In this paper feeding device, a double feeding prevention mechanism is provided in order to prevent double feeding of paper.

FIG. 6 is a schematic view showing a state of a sheet feeding standby state in a sheet feeding device using a separating pad system as a double feed preventing mechanism.

As shown in FIG. 6, the sheet feeding roller 30 is formed in a fan shape, and is rotated in the direction of arrow A in the figure by a driving device (not shown). The knock-up plate 31 that pushes up the paper P in the direction of the paper feed roller 30 is configured to rotate about the fulcrum 32 in the direction of arrow B in the drawing in conjunction with the rotation of the paper feed roller 30.

From the state shown in FIG. 6, the fan-shaped paper feed roller 3
When 0 is rotated in the direction of arrow A by a driving device (not shown), the knock-up plate 31 rotates in the direction of arrow B around the fulcrum 32 to lift the paper P and contact the paper feed roller 30 with a predetermined pressure. At this time, since the paper P is conveyed at one time, the separating member 20 is arranged on the extension of the outer circumference of the paper feeding roller 30, and a predetermined pressure is applied to the separating member 20 by the spring 21 to separate the paper P from the paper feeding roller 30. It is configured to separate the papers one by one between the members 20 to prevent the double feeding of the papers and to feed the papers one by one.

[0006]

However, in the above-described double feed prevention mechanism of the sheet feeding device, it is difficult to set each member for performing the paper separation, and further, the paper separation performance cannot be sufficiently exhibited. There are problems such as double feeding of paper due to differences in paper type and environment.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide a paper feeding device capable of reliably preventing double feeding of paper with a simple structure.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a sheet feeding device for feeding a sheet by feeding a fan-shaped sheet feeding roller with a separating member and separating the sheets one by one between the sheet feeding roller and the separating member. Sleeves having a diameter smaller than that of the paper feed roller and slightly extended in the rotation direction of the paper feed roller are provided on both sides of the paper feed roller, and the sleeve and the separation member are provided before the abutment member and the paper feed roller contact each other. Is abutted to separate the paper.

[0009]

According to the present invention, the sleeve comes into contact with the feed roller earlier than the feed roller before the separating member comes into contact with the feed roller.
Since the paper is fed by the paper feed roller while catching the leading edge of the paper with the sleeve, the separating performance is improved and the double feeding of the paper can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet feeding device of the present invention will be described below with reference to FIGS.

As shown in FIGS. 2 and 3, the drive unit in the sheet feeding apparatus of this embodiment has a sheet feeding gear having a toothed portion 3a on a roller shaft 2 of a fan-shaped sheet feeding roller 1. 3 is attached, and the paper feed gear 3 is provided so as to be engaged with a drive gear 4 for giving a drive force except during standby. That is, the paper feed gear 3 has a cutout 3
a is provided so that the drive gear 4 is located in the cutout portion 3a when the paper feed roller 1 is on standby, and the feed gear 3 and the drive gear 4 are configured to be disengaged from each other during standby. There is.

Further, a plate 6 having a cutout portion 6a for stopping the rotation of the paper feed gear 3 is attached to the feed roller shaft 2, and the cutout portion 6a of the plate 6 and the solenoid 7 are attached. When the flapper 7a comes into contact, the rotation of the paper feed gear 3 is stopped, and the paper feed roller 1 is stopped at a predetermined standby position.

Further, the roller shaft 2 is provided with a cam 9 for controlling the movement of the knock-up plate 8, and a plate holder 10 connected to the knock-up plate 8 abuts on the cam 9. The plate holder 10 is rotatably supported by a shaft 10b, and the plate holder 10 is biased toward the cam 9 by a biasing spring 10a attached to the plate holder 10.

Further, in the present invention, as shown in FIGS. 1 and 4, fan-shaped sleeves 11 are fixed to the roller shaft 2 so as to be positioned on both sides of the paper feed roller 1 in the axial direction.
The sleeve 11 has a width of 0.1 to 0.1 mm from the fan-shaped paper feeding roller 1.
It is set to have a small diameter within a range of up to 1.0 mm and is configured to project from the paper feed roller 1 in the rotation direction of the paper feed roller 1. That is, as shown in FIG.
1 is formed in a fan shape concentric with the paper feed roller 1, and its diameter is set to be smaller than the paper feed roller 1 within a range of 0.1 to 1.0 mm, and its arc portion is a paper feed roller. It is formed larger than 1.

Further, a separating member 20 is arranged on the extension of the outer circumference of the paper feed roller 1, and a predetermined pressure is applied to the separating member 20 by a spring 21.

Next, the paper feeding operation of the paper feeding device of the present invention will be described.

First, when the sheet is on standby, as shown in FIG.
The plate 6 attached to the roller shaft 2 is the solenoid 7
Since the paper feed gear 3 is in contact with the flapper 7a and the rotation of the paper feed gear 3 is stopped, the paper feed roller 1 is stopped at a predetermined standby position. At this time, the plate holder 10 has the urging spring 10
It is pressed against the cam 9 by the urging force of a. At the contact point between the plate holder 10 and the cam 9,
Since the slip is generated by the biasing force of the biasing spring 10a, the cam 9 receives the rotational force in the direction of the arrow in the figure.

Subsequently, as shown in FIG. 3, the solenoid 7
When the flapper 7a of is pulled in, the plate holder 1
Due to the urging force of the urging spring 10a given to 0, the paper feed gear 3 starts to rotate in the direction shown by the arrow in the figure. Then, the sheet feeding gear 3 meshes with the driving gear 4, and the driving force of the driving gear 4 causes the sheet feeding gear 3 to rotate, the sheet feeding roller 1 and the sleeve 11 to rotate, and sheet feeding is performed.

When there is no contact between the cam 9 and the plate holder 10, the rotational force applied to the paper feed gear 3 also disappears. However, since the paper feed gear 3 and the drive gear 4 are engaged with each other, the paper feed roller 1, the sleeve 11, and the cam 9 continue to rotate.

That is, as shown in FIG. 4, the roller shaft 2
The rotation of the paper feed roller 1 and the sleeve 11 rotates in the direction of arrow A. Then, the plate holder 10 and the cam 9
When the contact with the plate holder 10 and the knock-up plate 8 is released by the urging force of the urging spring 10a.
Moves in the direction of arrow B about the shaft 10b, the paper P is lifted by the knock-up plate 8 and contacts the paper feed roller 1 with a predetermined pressure.

At this time, friction occurs between the paper feed roller 1 and the paper P, and the paper is carried in the C direction, which is the direction of paper passage. However, since a plurality of papers are carried at one time, a fan-like shape is formed. The paper P is separated between the paper feed roller 1 and the separating member 20 one by one. FIG. 5 shows how the paper is separated in the paper feeder of the present invention.
Follow the explanation below.

FIG. 5 shows a fan-shaped feed roller 1 and a sleeve 1.
FIG. 1 is a schematic diagram showing the relationship of the separating member 20 when separating paper. As shown in FIG. 5, the sleeve 11 holds the front end of the paper P between the separating member 20 and the paper P discharged from the fan-shaped paper feed roller 1 as shown by D in the drawing. Then, the paper is separated between the fan-shaped paper feed roller 1 and the separating member 20 while grasping the leading end of the paper P with the sleeve 11. In this way, the paper is separated between the fan-shaped paper feed roller 1 and the separation member 20 while catching the leading edge of the paper P, so that the separation performance is improved.

Further, the paper feed roller 1 continues to rotate and the paper P is fed. Rotation of the paper feed roller 1, that is, the paper feed gear 3
When the rotation continues, the cam 9 contacts the plate holder 10 again. Then, the cam 9 continues to rotate, and the contact with the plate holder 10 exceeds the dead point. As a result, a rotational force is generated on the cam 9 by the pressing force of the plate holder 10.

On the other hand, the tooth-chipped portion 3a reaches the meshing point between the paper feed gear 3 and the drive gear 4. It is necessary to rotate the paper feed gear 3 from this position to the standby position by some means. In this embodiment, the cam 9 and the plate holder 1
Due to the rotational force generated by the contact with 0,
It can be rotated until it hits the flapper 7a of the solenoid 7. Then, in the state of FIG. 1, the paper feed roller 1 is
Wait until the next paper feed starts.

[0025]

As described above, according to the present invention, the sleeve comes into contact with the paper feed roller earlier than the paper feed roller before the separating member comes into contact with the paper feed roller, so that the paper feed roller can catch the leading edge of the paper. Since the sorting is performed, the sorting performance is remarkably improved as compared with the sorting performance in the conventional sheet feeding device, and the double feeding of paper can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a schematic top view showing an embodiment of a paper feeding device of the present invention.

FIG. 2 is a schematic side view showing a drive unit of an embodiment of the paper feeding device of the present invention.

FIG. 3 is a schematic side view showing a drive unit of an embodiment of the sheet feeding device of the present invention.

FIG. 4 is a schematic view showing a main part of an embodiment of a paper feeding device of the present invention.

FIG. 5 is a schematic view showing a main part of an embodiment of a paper feeding device of the present invention.

FIG. 6 is a schematic view showing a conventional paper feeding device.

[Explanation of symbols]

 1 Paper feeding roller 11 Sleeve 20 Separation member

Claims (1)

[Claims] 1. A paper feeding device for feeding a fan-shaped paper feeding roller with a separating member in contact with each other so as to separate the paper one by one between the paper feeding roller and the separating member. A sleeve having a diameter smaller than that of the roller and slightly extending in the rotation direction of the paper feeding roller is provided, and the sleeve and the separating member are brought into contact with each other before the separating member comes into contact with the paper feeding roller to separate the paper. A paper feeding device characterized by the above.