JPH05139550A - Paper feeding device - Google Patents

Abstract

PURPOSE:To enable constantly stable paper feeding by separating only the uppermost paper sheet from other paper sheets by means of separation rollers and the first carrying roller, and feeding this separated paper sheet to the paper sheet carrying passage side in a secure manner by means of the first and the second paper feeding rollers. CONSTITUTION:When a start button is pushed, a frame body 21 is lowered by means of an actuator, and the first paper feeding rollers 27, 28 and separation rollers 31, 32 are brought into contact with the upper surface of paper sheets. The fist feed rollers 27, 28 are rotated in the paper feed direction at the specified timing, and at the same time, the separation rollers 31, 32 are rotated in the reverse direction of the paper feeding direction, and these rotations allow the uppermost paper sheet in a paper feeding cassette 4 to be deflected between the rollers 31, 32, and the deflected paper sheet is moved in the paper feeding direction by the stiffness of the paper sheet itself and the feeding force of the first paper feeding rollers 27, 28. The separation rollers 27, 28 are further rotated and separated from the upper surface of the paper sheet, the paper sheet is moved by the stiffness of the paper sheet itself and the feeding force of the first paper feeding rollers 27, 28.

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 for feeding a sheet while preventing double feeding of the sheet from a sheet storage section.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine or a laser printer is provided with a sheet feeding device for feeding a sheet to an image forming section. This paper feed device has a paper feed roller for feeding the paper in a paper storage unit such as a paper feed cassette from the paper feed cassette, and a double feed prevention mechanism for feeding the paper one by one from the cassette. There is.

As a conventional device of this type, Japanese Patent Application Laid-Open No. 55-
There is one disclosed in Japanese Patent No. 74927. This device
It has a sheet feeding roller for forward feeding arranged above the sheet feeding cassette, and an eccentric roller provided on the downstream side of the sheet feeding roller in the sheet conveying direction. The eccentric roller is provided such that the roller is eccentric with respect to the rotating shaft, and when the eccentric roller makes one rotation, its surface comes into contact with the paper in the paper feed cassette only for a certain period. ing.
Also, the paper feed roller rotates in the direction to feed the paper,
The eccentric roller rotates in the direction opposite to the paper feeding direction.

When the paper is sent out by this apparatus, the paper feed roller first contacts the upper surface of the paper. At this time, the rotation is stopped. In this state, the eccentric roller starts rotating in the direction opposite to the direction in which the paper is sent out. In the initial state, the eccentric roller is not in contact with the paper. Then, when the paper is rotated, for example, 180 ° from the initial state, the surface of the eccentric roller contacts the upper surface of the paper, and the paper is sent to the paper feed roller side by the eccentric roller for a certain period. Since the paper feed roller is stopped, the paper is curved between the eccentric roller and the paper feed roller, so that only the uppermost paper is separated from the other paper. Then, when the eccentric roller continues to rotate further, the surface of the eccentric roller separates from the upper surface of the sheet. The sheet is sent out from the inside of the sheet feeding cassette by the repulsion deflected by the eccentric roller and by the rotation of the sheet feeding roller in the sheet feeding direction.

In this way, only the uppermost one sheet in the paper feed cassette is sent out from the paper feed cassette.

[0006]

In the sheet feeding device disclosed in the above publication, after the eccentric roller is separated from the sheet, the sheet is fed by the strength of the waist and the sheet feeding roller. That is, it is only the paper feed roller that positively feeds the paper. For this reason, it is necessary to strictly control the paper feed force of the paper feed roller, and it is difficult to set the contact force for the paper. For this reason, there are cases in which the paper cannot be delivered properly from the paper feed cassette.

An object of the present invention is to ensure that the paper can be delivered from the paper feed cassette.

[0008]

A sheet feeding device according to the present invention is a device for feeding out a sheet from a sheet storage section while preventing double feeding of the sheet, and includes a first sheet feeding roller, a separating roller, and A second paper feed roller and a transmission mechanism are provided. The first paper feed roller can contact the paper in the paper storage unit and can rotate in the direction of feeding the paper in the paper storage unit. The separating roller is disposed downstream of the first paper feeding roller in the paper feeding direction, and has a contact portion capable of abutting the paper in the paper storage portion on a part of the outer periphery and is rotatable. The second paper feed roller has an abutting portion capable of abutting the paper in the paper storage portion on a part of the outer periphery thereof, and is located on the downstream side of the first paper feeding roller in the paper feeding direction and abutting portion of the separating roller. The contact portion is arranged so as to contact the paper when the paper is not in contact with the paper, and is rotatable. The transmission mechanism is a mechanism that connects both rollers so that the separating roller rotates in the direction opposite to the paper feeding direction and the second paper feeding roller rotates in the paper feeding direction.

[0009]

In the paper feeding device according to the present invention, when the paper is sent out, the first paper feeding roller contacts the paper in the paper storage unit. In this state, the separating roller rotates in the direction opposite to the paper feeding direction. The rotation of the separation roller is transmitted to the second paper feed roller by the transmission mechanism, and the second paper feed roller rotates in the paper delivery direction. When the separating roller rotates by a predetermined angle, the contact portion formed on a part of the outer periphery thereof contacts the paper in the paper storage unit. This contact causes the paper to
It is sent to the paper feed roller side. At this time, since the first paper feed roller is stopped or is rotating in the paper feeding direction,
The paper is curved between the first paper feed roller and the separation roller,
Only the top sheet is separated from the sheets below it. When the contact portion of the separating roller is in contact with the paper, the contact portion of the second paper feed roller is not in contact with the paper.

Next, when the separating roller is further rotated and its abutting portion is separated from the paper, the feeding of the paper to the first paper feed roller side is released, so that the paper depends on its strength. Further, the rotation of the first paper feed roller causes the paper to be sent out from the paper storage unit. At this time, a part of the outer periphery of the second paper feed roller, which rotates in the paper feeding direction, comes into contact with the paper, and the paper comes into contact with the first paper feed roller by the abutment part of the second paper feed roller. It is sent out from the storage.

As described above, the sheet separated by the separating roller is reliably delivered from the inside of the sheet storage section by the first sheet feeding roller and the second sheet feeding roller.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall construction of a copying machine to which an embodiment of the present invention is applied. A document table 2 is fixed on the upper surface of the copying machine body 1, and a document retainer 3 is provided on the document table 2.
Is installed so that it can be opened and closed. A paper feed cassette 4 is detachably attached to the right side of the copying machine main body 1. On the left side, a paper discharge tray 6 for discharging the copied paper is mounted.

Inside the main body 1 of the copying machine, an optical system 7 for reading image information of a document is provided at the upper part. The optical system 7 is composed of a light source, a mirror, a lens and the like. A photoconductor drum 8 on the surface of which an electrostatic latent image is formed is arranged at the center of the inside of the copying machine main body 1. Around the photoconductor drum 8, a charging device 9 that charges the photoconductor drum 8 to a predetermined electric charge, a developing device 10 that develops an electrostatic latent image, a transfer device 11 that transfers a toner image to a sheet, and a photoconductor. A sheet separating device 12 for separating the sheet from the drum 8 and a cleaning device 13 for removing the toner on the photosensitive drum 8 are sequentially arranged.

A paper feeding / transporting path 14 for transporting the paper is provided between the paper feeding cassette 4 and the image forming portion constituted by the photosensitive drum 8 and the like. Further, a paper discharge transport path 15 is provided on the downstream side of the image forming unit in the paper transport direction. A fixing device 16 for fixing the transferred image on the conveyed sheet and a discharge roller 17 are provided between the sheet discharge passage 15 and the discharge tray 6.

Above the front end of the paper feeding cassette 4, a paper feeding device 20 for feeding the paper in the paper feeding cassette 4 to the paper feeding and conveying path 14 is provided. As shown in FIG. 2, the sheet feeding device 20 has a frame body 21 that can be raised and lowered. Frame 2
1 has side frames 21a and 21b in the front-back direction of the apparatus. A first rotating shaft 22 and a second rotating shaft 23 are rotatably supported by the front and rear side frames 21a and 21b, respectively. The first rotary shaft 22 is arranged on the downstream side of the second rotary shaft 23 in the paper feeding direction, and one end thereof is connected to a drive motor via a drive system (not shown). The first rotary shaft 22 and the second rotary shaft 23 have pulleys 2 respectively.
4, 25 are fixed, and a belt 26 is crossed over the pulleys 24, 25. As a result, both rotary shafts 22 and 23 rotate in opposite directions. Second rotating shaft 2
A pair of first paper feed rollers 27, 28 are provided on both sides of the sheet 3 in the width direction.
Is fixed. The paper feed rollers 27 and 28 have the same diameter, and when the frame 21 is lowered, the paper feed rollers 27 and 28 can come into contact with the uppermost paper main switch in the paper feed cassette 4.

A second paper feed roller 30 is provided at the center of the first rotary shaft 22 in the width direction. The second paper feed roller 30 is supported by the first rotating shaft 22 via a bearing, and can rotate independently of the second rotating shaft 23. As shown in FIGS. 3 to 5, the second paper feed roller 30 is formed in a fan shape in side view. Therefore, the second
When the paper feed roller 30 rotates, a part (contact portion) of the paper feed roller 30 can contact the upper surface of the paper in the paper feed cassette 4 only at a predetermined rotation angle. Further, separating rollers 31 and 32 are arranged on both left and right sides of the second paper feed roller 30. The pair of separating rollers 31 and 32 are
It is fixed to the rotary shaft 22 and rotates together with the second rotary shaft 22. Each of the separating rollers 31 and 32 is formed in a fan shape in a side view, like the second paper feeding roller 30. Therefore, when the separating rollers 31 and 32 rotate,
Only at a predetermined rotation angle, a part (contact portion) can contact the upper surface of the sheet. The second paper feed roller 3
The 0 and the separating rollers 31 and 32 have the same diameter as the first paper feeding rollers 27 and 28, respectively.

On the other end side of the second rotary shaft 22, the first gear 3
5 is fixed. A first intermediate shaft 36 and a second intermediate shaft 37 are rotatably supported by the side frame 21a. The other end of the second intermediate shaft 37 is supported by a support frame 21c fixed to the side frame 21a. A second gear 38 meshing with the first gear 35 is fixed to the first intermediate shaft 36, and a third gear meshing with the second intermediate shaft 38 is provided at one end of the second intermediate shaft 37.
The gear 39 is fixed. The fourth gear 40 is fixed to the other end of the second intermediate shaft 37. A fifth gear 41 that rotates integrally with the second paper feed roller 30 is fixed to the other end of the second paper feed roller 30.
Meshes with the fourth gear 40.

With such a structure, when the first rotating shaft 22 rotates in the direction opposite to the paper feeding direction, the second paper feeding roller 30 is moved through the first to fifth gears 35, 38, 39, 40 and 41. Rotate in the paper feeding direction. In the initial state, the contact portion of the second sheet feeding roller 30 is located above, and the separating rollers 31 and 32 are located so that the contact portion contacts the sheet.

Next, the operation will be described. When the copy start button is pressed and the copy operation is started, the frame 2
1 is lowered by an actuator (not shown), whereby the first paper feed rollers 27, 28 and the separating roller 3
1, 32 contact the upper surface of the sheet. Then, at a predetermined timing, the first paper feed rollers 27 and 28 rotate in the paper feeding direction, and the separating rollers 31 and 32 rotate in the direction opposite to the paper feeding direction. As a result, as shown in FIG. 3, the uppermost sheet in the sheet feeding cassette 4 is bent between the rollers. The bent sheet is about to move in the sheet feeding direction due to the strength of its waist and the feeding force of the first paper feed rollers 27 and 28. In this state, when the separating rollers 31 and 32 further rotate and move away from the upper surface of the paper (see FIG. 4), the paper is fed by the strength of its waist and the feeding force of the first paper feed rollers 27 and 28 to the paper feed conveyance path 14 side. Sent to. When the paper is fed by a predetermined amount, the trailing edge of the paper is fed by the first paper feed roller 2
Move away from 7,28. However, as shown in FIG. 5, the fed-out sheet is conveyed further forward by the second sheet feeding roller 30 that rotates in the sheet feeding direction via each gear, so that the sheet is reliably fed to the sheet feeding conveying path 14. Can be sent out.

As described above, in this embodiment, the separating roller 3 is used.
1, 32 and the first paper feed rollers 27, 28 separate only the uppermost paper from other papers, and the separated paper is reliably fed and conveyed by the first paper feed roller and the second paper feed roller. Since the sheet is sent to the side of the path 14, stable sheet feeding can be performed. [Other Embodiments] (a) In the above embodiment, the separating rollers 31 and 32 and the second paper feed roller 30 are rotated in reverse by using gears, but they may be rotated in reverse by using a belt or the like. May be. (B) In the above-described embodiment, the shape of the separating rollers 31 and 32 and the second paper feeding roller 30 is a fan shape in side view, but the shape of each roller is not limited to this and, for example, a part of the outer circumference. The shape may be such that a protrusion is provided on the.

Both rollers may be eccentric rollers.

[0022]

As described above, according to the present invention, the uppermost sheet in the sheet storage section is separated from other sheets by the separating roller and the first sheet feeding roller, and the separated sheet is separated by the first sheet feeding roller and the first sheet feeding roller. Since the paper is fed by the second paper feed roller, the paper can be reliably fed from the paper storage unit, and stable paper feeding can be always performed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a copying machine in which a sheet feeding device according to an embodiment of the present invention is adopted.

FIG. 2 is a plan view of a sheet feeding device.

FIG. 3 is a schematic side view of the sheet feeding device showing the operation of the separating roller.

FIG. 4 is a schematic side view of the sheet feeding device showing a sheet feeding operation.

FIG. 5 is a schematic side view of the sheet feeding device showing a sheet feeding operation.

[Explanation of symbols]

 4 Paper Feed Cassette 20 Paper Feed Device 27, 28 First Paper Feed Roller 30 Second Paper Feed Roller 31, 32 Separation Roller 35, 38, 39, 40, 41 Gear

Claims (1)

[Claims] 1. A sheet feeding device for feeding a sheet while preventing double feeding of the sheet from the sheet storing section, the sheet feeding apparatus being capable of contacting the sheet in the sheet storing section and rotating in a feeding direction of the sheet in the sheet storing section. A rotatable first sheet feeding roller, and a rotatable separating member having a contact portion arranged downstream of the first sheet feeding roller in the sheet feeding direction and having a contact portion capable of contacting the sheet in the sheet storing portion at a part of the outer circumference. A roller, and an abutting portion capable of abutting the paper in the paper storage portion on a part of the outer periphery, and the abutting portion of the separating roller is downstream of the first paper feeding roller in the paper feeding direction. A rotatable second paper feed roller arranged so that the abutting portion abuts the paper when not in contact with the sheet; and the separating roller is in a direction opposite to the paper feeding direction, and the second paper feed roller is the paper feeding roller. Both rollers are rotated so that they rotate in the feeding direction. A sheet feeding device having a transmission mechanism to be connected.