JPH09240868A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform the separation state of a paper sheet, regardless of the number of a set paper sheet when the paper sheet heading for a paper sheet separation mechanism after being picked up by a pick up roller is separated by a paper bump plate. SOLUTION: This device is constituted so that a paper sheet 1 is contacted with a pick up roller 6 after pushing up a bottom plate 3 and a pick up fed paper sheet 1 is separated by a separation mechanism 7 and only the most upper paper is fed. A paper sheet bump plate 11 for separating the paper sheet 1 heading for the separation mechanism 7 after being pickup-fed at the upper edge part is installed in a paper feed direction swingably between the pick up roller 6 and the separation mechanism 7. This paper sheet bump plate 11 is inclined toward the paper feed direction when a swing locus is interfered with the tip of the bottom plate 3 and contacted to the tip of the bottom plate 3. Thereby, the contact angle of the tip of the paper sheet 1 for the paper sheet bump plate 11 is balanced to the slide distance when the paper sheet 1 slides and gets over the paper sheet bump plate 11 in response to the number of loaded paper sheet 1 and the separation state of the paper sheet 1 is stabilized, regardless of the number of loaded paper sheet 1.

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 pushing up a bottom plate on which a plurality of sheets are stacked to bring the topmost sheet into contact with a pickup roller and picking up and feeding the sheet with the pickup roller.

[0002]

2. Description of the Related Art In this type of paper feeding device, a structure is widely used in which the picked up and fed paper is sent to a separating mechanism and only the uppermost paper is separated and fed by the separating mechanism. There is. As a separating mechanism used in the sheet feeding device having such a structure, a separating mechanism including a feed roller and a friction pad and a separating mechanism including a feed roller and a reverse roller have been generally used conventionally. Then, in the sheet feeding device having such a separating mechanism, a contact plate with a paper on which the leading end of the paper hits before reaching the separating mechanism is provided, and the paper abutting plate picks up the fed paper and picks it up. A structure having a structure in which the amount of paper picked up by rollers can be regulated is also known, and is described in, for example, Japanese Utility Model Publication No. 7-38283.

[0003]

A paper abutting plate is provided,
In addition, in the paper feeding device in which the bottom plate is raised so that the sheets stacked on the bottom plate are brought into contact with the pickup rollers, the contact angle of the leading edge of the sheet with respect to the sheet abutting plate is changed according to the amount of sheets loaded on the bottom plate. It will change. Therefore, there is a problem in that the separation state of the sheets by the sheet abutting plate varies depending on the number of sheets stacked and is not stable.

[0004]

According to the first aspect of the present invention,
A paper feed cassette that stores a plurality of sheets of paper, a bottom plate that is swingably attached to the paper feed cassette at a rear end fulcrum to stack and hold paper, a push-up mechanism that pushes up the bottom plate at a predetermined timing, and a push-up mechanism. The pickup roller is placed at a position where the sheets stacked on the bottom plate pushed up by the mechanism come into contact with each other, and the pickup roller that is driven to rotate at a predetermined timing and the sheet picked up by this pickup roller are separated to feed only the top sheet. It is mounted swingably in the paper feed direction between the separation mechanism and the pickup roller and the separation mechanism, and its swing trajectory interferes with the tip of the bottom plate and is directed in the paper feed direction when it comes into contact with the tip of the bottom plate. And a sheet abutting plate that picks up and feeds the sheet that is picked up and fed toward the separating mechanism at its upper edge portion.

Therefore, as the number of sheets stacked on the bottom plate decreases, the sheet abutting plate largely inclines toward the sheet feeding direction. As a result, when the number of sheets stacked on the bottom plate is large, the angle at which the leading edge of the sheets picked up and fed to the pickup roller contacts the sheet abutting plate becomes tight, but the sheet slides on the sheet abutting plate. The sliding distance when moving and getting over becomes shorter. On the other hand, when the number of sheets stacked on the bottom plate is small, the angle at which the leading edge of the sheets picked up and fed to the pickup roller contacts the sheet abutting plate becomes gentle, but the sheet is abutted on the sheet abutting plate. The sliding distance when sliding and getting over becomes longer. Here, the tighter the contact angle of the leading edge of the paper with respect to the paper abutting plate, the greater the force for separating the paper, and the longer the sliding distance when the paper slides over the paper abutting plate, the greater the force for separating the paper. To do. Therefore, regardless of the number of sheets stacked on the bottom plate, the force for separating the sheets from the sheet abutting plate becomes uniform, and the separated state of the sheets is stable.

According to a second aspect of the present invention, in the sheet feeding device according to the first or second aspect, the upper edge portion of the sheet abutting plate has a contact position of the pickup roller with respect to the sheet and a sheet passing position in the separating mechanism. Interferes with the connecting straight line. Therefore, the paper is reliably separated by the paper abutting plate.

The invention according to claim 3 is the invention according to claims 1 to 3.
In the paper feeding device according to any one of the above, the portion of the paper abutting plate that separates the paper has an elastic force and a high friction coefficient. Therefore, the sheet is favorably separated at the portion having the elastic force and the high friction coefficient.

The invention according to claim 4 is the invention according to claims 1 to 4.
In the paper feeding device according to any one of the above, the central portion of the upper edge portion of the sheet abutting plate projects more than both side portions. Therefore, even if both ends of the paper are back-curled, the back-curled portion is not caught by the paper abutting plate, and the skew or non-feeding of the paper is prevented.

[0009]

An embodiment of the present invention will be described with reference to the drawings. A paper feed cassette 2 for accommodating a plurality of sheets of paper 1 is provided. The paper feed cassette 2 is detachably attached to an image forming apparatus (not shown). Further, inside the paper feed cassette 2, the bottom plate 3 has a fulcrum 4 at the rear end.
It is attached so that it can swing around. And
A notch 5 is formed at the bottom of the paper feed cassette 2, and a push-up mechanism (not shown) on the image forming apparatus side enters the paper feed cassette 2 from the notch 5 and pushes up the bottom plate 3. Has been done.

On the other hand, the image forming apparatus is provided with a pickup roller 6 and a separating mechanism 7. The pickup roller 6 is arranged at a position where the sheets 1 stacked on the bottom plate 3 pushed up by the push-up mechanism come into contact with each other, and is rotationally driven at a predetermined timing. The separating mechanism 7 includes a feed roller 8 and
The feed roller 8 is in contact with the reverse roller 9. The reverse roller 9 is rotationally driven in a direction to push back the paper 1, and has a torque limiter (not shown) in its drive transmission path. Therefore, the reverse roller 8 is normally rotated by the feed roller 8 and pushes back the paper 1 only when the paper 1 is double-fed to the paper passage 10 formed between the feed roller 8 and the reverse roller 9. Driven to rotate.

Next, a sheet abutting plate 11 is attached to the sheet feeding cassette 2 so as to be swingable in the sheet feeding direction. The sheet abutting plate 11 is formed by fixing a flat plate portion 13 to a base 12 having both ends bent at right angles. The plate portion 13 has an elastic force and a high coefficient of friction, and is formed by, for example, sticking rubber-containing cork or non-woven fabric to a resin film, or by subjecting the surface of a leaf spring material to a roughening treatment. There is. Then, the support pins 14 of the sheet feeding cassette 2 are fitted to both ends of the base 12 that are bent, and the sheet abutting plate 11 is attached to the sheet feeding cassette 2.

Here, the paper abutting plate 11 is tilted toward the paper feeding direction when its swing locus interferes with the tip of the bottom plate 3 and comes into contact with the tip of the bottom plate 3, picked up and fed, and separated. The upper edge portion of the sheet 1 facing the mechanism 7 is separated. The upper edge portion of such a paper abutting plate 11 is
The central part projects more than both sides. The protruding central portion of the upper edge portion of the sheet abutting plate 11 has a contact position of the pickup roller 6 with respect to the sheet 1 and the separating mechanism 7.
It is formed so as to interfere with a straight line connecting with the sheet passing position.

In such a structure, at the time of sheet feeding, the bottom plate 3 is pushed up by a push-up mechanism (not shown), so that the sheets 1 stacked on the bottom plate 3 come into contact with the pickup rollers 6. Then, when the pickup roller 6 is rotationally driven, the stacked sheets 1 are picked up and fed, and sent to the separation mechanism 7. At this time, when the paper 1 is double-fed, the reverse roller 9 which is normally rotated by the feed roller 8 is rotationally driven in the direction to push back the paper 1, and the multi-fed paper 1 is separated. Only the uppermost paper is fed to a paper transport path (not shown) of the image forming apparatus.

When the sheet 1 is separated and fed as described above, the sheet 1 picked up and fed to the pickup roller 6 abuts against the sheet abutting plate 11 and is separated. That is, it is possible to prevent the sheet abutting plate 11 from sliding over and feeding at least a large amount of the sheets 1 to the separating mechanism 7. At this time, since the portion of the sheet abutting plate 11 that separates the sheet 1 has an elastic force and a high friction coefficient, the sheet 1 is separated well at the portion having the elastic force and a high friction coefficient.
Further, since the central portion of the upper edge portion of the sheet abutting plate 11 projects more than both side portions, even if both ends of the sheet 1 are back-curled, the back-curling portion is the sheet abutting plate 1.
Therefore, the sheet 1 is prevented from being caught and the sheet 1 is prevented from being skewed or not fed.

Since the sheet abutting plate 11 is pushed by the sheet 1 to be picked up and fed, the sheet abutting plate 11 swings and abuts on the tip of the bottom plate 3 when the sheet 1 is picked up and fed. For this reason, the paper abutting plate 11 is used for the paper 1 stacked on the bottom plate 3.
The smaller the number of sheets, the greater the inclination toward the paper feeding direction. As a result, when the number of sheets 1 stacked on the bottom plate 3 is large, the angle at which the leading edge of the sheet 1 picked up and fed to the pickup roller 6 contacts the sheet abutting plate 11 is large, while the sheet 1 is The sliding distance when sliding over the sheet abutting plate 11 is shortened. On the other hand, when the number of sheets 1 stacked on the bottom plate 3 is small, the angle at which the leading edge of the sheet 1 picked up and fed to the pickup roller 6 contacts the sheet abutting plate 11 is gentle, but the sheet 1 is small. The sliding distance becomes longer when the paper slides over the paper abutting plate 11 and gets over it. Here, the tighter the contact angle of the leading edge of the sheet 1 with respect to the sheet abutting plate 11, the greater the force for separating the sheet 1, and the longer the sliding distance when the sheet 1 slides over the sheet abutting plate 11 and gets over The force to handle the paper is increased.
Therefore, regardless of the number of sheets 1 stacked on the bottom plate 3, the force for separating the sheets 1 on the sheet abutting plate 11 becomes uniform, and the separated state of the sheets 1 is stabilized.

The stabilization of the separated state of the sheet 1 due to the variation of the inclination angle of the sheet abutting plate 11 will be described with reference to FIG. As shown in FIG. 1, the sheet abutting plate 11 and the sheet 1
The angle θ formed by and θ is θ when the number of stacked sheets of paper 1 is large.
1 (FIG. 1 (b)) and θ2 (FIG. 1 (a)) when the number is small, and the relationship of θ1> θ2 is established. As a result, when the number of sheets 1 stacked on the bottom plate 3 is large, the angle at which the leading edge of the sheet 1 picked up and fed to the pickup roller 6 contacts the sheet abutting plate 11 becomes tight, and the sheets 1 are stacked on the bottom plate 3. It can be seen that when the number of sheets 1 to be formed is small, the angle at which the front end of the sheet 1 picked up and fed to the pickup roller 6 contacts the sheet abutting plate 11 becomes gentle. On the other hand, the protrusion amount of the sheet abutting plate 11 with respect to the straight line connecting the contact position of the pickup roller 6 with respect to the sheet 1 and the sheet passing position of the separation mechanism 7 is h1 (see FIG. b)), h2 (Fig. 1)
(A)), and the relationship is h2≈h1. in this case,
The sliding distance between the paper 1 and the paper abutting plate 11 is h2≈h1
Then, it is obvious that the sheet abutting plate 11 is longer when it is more inclined. That is, when the number of the sheets 1 stacked on the bottom plate 3 is large, the sheets 1 are pushed against the sheet abutting plate 1.
The sliding distance when sliding over 1 becomes shorter and the bottom plate 3
It can be seen that when the number of the sheets 1 stacked on the sheet 1 is small, the sliding distance when the sheets 1 slide on the sheet abutting plate 11 and get over the sheet 1 becomes long.

[0017]

According to the first aspect of the present invention, the pickup roller and the separating mechanism are mounted so as to be swingable in the sheet feeding direction, and the swing locus interferes with the tip of the bottom plate and hits the tip of the bottom plate. Since it has a paper abutting plate that tilts toward the paper feed direction when touching, picks up and feeds the paper toward the separation mechanism at the upper edge portion, regardless of the number of sheets loaded on the bottom plate, The force of separating the paper from the paper abutting plate can be made uniform, so that the separated state of the paper can be stabilized.

According to a second aspect of the present invention, in the sheet feeding device according to the first or second aspect, the upper edge portion of the sheet abutting plate has a contact position of the pickup roller with respect to the sheet and a sheet passing position in the separating mechanism. Since it interferes with the connecting straight line, it is possible to improve the sheet separating performance by the sheet abutting plate.

The invention according to claim 3 is the same as claims 1 to 3.
In the paper feeding device described in any one of the above, since the portion of the sheet abutting plate for separating the sheet has an elastic force and a high friction coefficient, the sheet separating performance of the sheet abutting plate can be improved.

The invention according to claim 4 is the invention according to claims 1 to 4.
In the paper feeding device according to any one of the above, since the central portion of the upper edge portion of the sheet abutting plate projects more than both side portions,
Even if both ends of the paper have back curl, it is possible to prevent the back curl part from being caught by the paper abutting plate, and therefore the paper skew or non-feeding caused by the paper being caught by the paper abutting plate. Can be prevented.

[Brief description of drawings]

FIG. 1 is an overall vertical cross-sectional side view showing an embodiment of the present invention in which (a) shows a case where there are few sheets stacked on a bottom plate and (b) shows a case where there are many sheets stacked on a bottom plate. It is a figure.

FIG. 2 is a perspective view of a sheet abutting plate.

[Explanation of symbols]

 1 paper 2 paper feed cassette 3 bottom plate 6 pickup roller 7 separation mechanism 11 paper abutting plate

Claims (4)

[Claims] 1. A paper feed cassette for accommodating a plurality of paper sheets, a bottom plate which is swingably attached to the paper feed cassette at a rear end fulcrum to stack and hold the paper sheets, and the bottom plate is pushed up at a predetermined timing. A push-up mechanism, a pickup roller arranged at a position where the sheets stacked on the bottom plate pushed up by the push-up mechanism come into contact with each other, and rotationally driven at a predetermined timing, and the sheets picked up by the pickup rollers are separated. And a separation mechanism that feeds only the topmost paper, and is swingably attached between the pickup roller and the separation mechanism in the sheet feeding direction, and the swing locus interferes with the tip of the bottom plate, A paper abutting plate that tilts toward the paper feed direction when it comes into contact with the tip of the bottom plate, picks up and feeds the paper toward the separating mechanism at the upper edge portion, and A paper feeding device characterized in that 2. The sheet feeding device according to claim 1, wherein an upper edge portion of the sheet abutting plate interferes with a straight line connecting a contact position of the pickup roller with respect to the sheet and a sheet passing position of the separating mechanism. . 3. The sheet abutting plate, which separates the sheet, has an elastic force and a high friction coefficient.
Alternatively, the sheet feeding device described in 2. 4. The paper feeding device according to claim 1, wherein a central portion of the upper edge portion of the sheet abutting plate projects more than both side portions.