JPH0769467A - Paper feeder of image former - Google Patents

Abstract

PURPOSE:To provide a paper feeder fair an image former, which is simple in structure and inexpensive in cost, and besides, there is no wrongfulness such as a fold of recording paper and a misfeeding operation in time of paper feeding. CONSTITUTION:A bottom plate 11 imparted with an upward pushing force by dint of a compression spring 12 is installed in a cassette type tray 10. Recording paper 3 is stacked on this bottom plate 11. An uppermost position of the recording paper 3 is regulated to a constant position by a presser claw 13 (14). In addition, a paper feed roller 2 is installed so as to come into contact with the uppermost position of the recording paper 3. A friction member 4 being free of rotation is installed in space between the paper feed roller 2 and the claw 13 (14). Moreover, a pair of feed rollers 5 are installed in the feeding direction of the recording paper 3.

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 recording sheet to an image forming apparatus such as a copying machine, a printer, a facsimile or a printing machine for forming an image on the recording sheet.

[0002]

2. Description of the Related Art Various types of image forming apparatuses for forming an image on recording paper are in widespread use, and many types of paper feeding devices for supplying the recording paper to the image forming apparatus are also adopted.
Above all, stacking recording paper in a cassette type tray,
The most commonly known type is a sheet feeding device that feeds recording sheets one by one to an image forming apparatus as needed. Even in the paper feeding device of this type, the recording papers stacked in the tray are separated one by one by using the pawls (corner pawls) provided at the corners of the cassette type tray and supplied to the image forming apparatus. The so-called corner separator system is one of the simplest and most inexpensive paper feeders.

In the corner separator system, since the recording papers are separated one by one by utilizing the buckling property of the supplied recording papers, the positions of the corner claws and the feed rollers with respect to the recording papers stacked in the tray. Relationships are important. However, since there are only one or two cassette-type trays for various sizes of recording paper, the positional relationship between the corner claws and the paper feed roller for the maximum size recording paper and the corner claws for the minimum size recording paper are different. The positional relationship between the paper feed rollers is different. For this reason, when the recording paper is separated and fed, there is a problem that a corner of the recording paper is broken or a problem such as non-feeding (misfeed) occurs. In addition, the actual development Sho 56-1
73543 discloses that instead of the corner claws, a separation claw is arranged at the center of one side of a cassette type tray, but it has the same problem as the corner separator method described above. From the point of view of the place, it is more likely to be deformed or damaged than the corner claws, and the replenisher is likely to come into contact when replenishing the recording paper in the tray, which is a safety problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not cause problems such as bending and misfeed of the recording paper at the time of paper feeding.
A sheet feeding device for an image forming apparatus having a simple structure and low cost.

[0005]

The sheet feeding device of the present invention separates the stacked recording sheets one by one and supplies them to the image forming apparatus. A claw member provided so as to abut on an edge of the uppermost surface in the feeding direction, a rotatable sheet feeding roller which comes into contact with the uppermost surface of the recording sheet and sends out the uppermost recording sheet in the feeding direction, and the claw member An image forming apparatus having a rotatable friction member that is disposed between the sheet feeding roller and the sheet feeding roller, is in contact with the uppermost surface of the recording sheet, and applies a force to the uppermost recording sheet in a direction opposite to the feeding direction. It is a paper feeding device.

Another paper feeding apparatus of the present invention is a paper feeding apparatus for an image forming apparatus, wherein the above paper feeding apparatus is provided with a bent guide plate disposed between the claw member and the paper feeding roller. is there.

The details of the present invention will be described below.

FIG. 1 shows a state in which a cassette type tray 10 on which recording papers 3 are stacked is mounted on an image forming apparatus 1 such as a copying machine. The cassette type tray 10 is the image forming apparatus 1
On the other hand, it is detachable from the front side (A side). After being mounted, the recording paper 3 in the cassette type tray 10 is conveyed into the image forming apparatus 1 by the paper feed roller 2.

FIG. 2 is a cross-sectional view as seen from the direction E in FIG. 1, showing a main part of the paper feeding device of the present invention.

A bottom plate 11 whose one end is rotatably supported is provided in the cassette type tray 10, and recording papers 3 are stacked on the bottom plate 11. Here, recording paper 3
Are positioned within the tray by a front wall 10a of the tray, a pair of side walls (not shown) and a rear wall (not shown). Further, the bottom plate 11 is given a force to push it upward by a compression spring 12 provided in the lower portion. On the other hand, the front wall 10a of the tray is provided with a pair of pressing claws 13 (14) slidable in a vertical direction by a predetermined amount. The pressing claw 13 (14) is a portion 13a for receiving the cut surface of the recording papers 3 stacked in the tray.
It has a portion 13b for receiving the upper edge of the uppermost recording sheet 3 and a stopper portion 13c for defining the upper limit of sliding. Normally, the uppermost position of the recording sheets 3 stacked in the tray is fixed at a fixed position (that is, as shown in FIG. 2) by the bottom plate 11 and the pressing claws 13 (14) to which a pushing-up force is applied. 14) Upper limit position of slide).

Above the recording papers 3 stacked in the tray, there is provided a paper feed roller 2 having a shape in which a part of an arc is cut off. A rotatable friction member 4 formed by a part of an arc is provided between the paper feed roller 2 and the pressing claw 13 (14). The peripheral edge portion 4a of the friction member 4 is preferably formed of a high friction material such as rubber in order to improve the contact with the recording paper 3. Further, as shown in FIG. 4, it is preferable that the portion 4b following the peripheral edge portion 4a is a recessed portion so as not to interfere with the feeding of the recording paper 3 and has a concave shape. A feed roller pair 5 is provided in the feeding direction of the recording paper 3.

FIG. 5 is a view of the main part of the paper feeder of FIG. 2 as seen from above. When the recording sheets 3 are stacked in the central portion of the cassette type tray 10, it is preferable to arrange the sheet feeding roller 2, the friction member 4 and the feed roller pair 5 on the center line of the tray in the feeding direction. The paper feed roller 2 is
Via a paper feed roller shaft 6 extending to the rear of the paper feed device, it is connected to a drive source 7 such as a clutch (not shown) for controlling rotation and a motor for drive control. Similarly, the friction member 4 is also connected to the paper feed roller shaft 6 via a friction member shaft 8 extending rearward of the paper feed device and a gear train (not shown), and rotation control is performed in synchronization with the paper feed roller 2. To be done.

When the cassette type tray 10 on which the recording papers 3 are stacked and mounted is attached to or detached from the image forming apparatus 1 such as a copying machine, the paper feed roller 2 and the friction member 4 are provided with an open circle as shown in FIG. Since the recording paper 3 is controlled so as to face the recording paper 3, the recording paper 3 does not come into contact with the paper feed roller 2 or the friction member 4 to cause a problem.

Next, the feeding operation of the recording paper 3 will be described with reference to FIGS. 3 and 4.

By the drive source 7 such as a motor, the paper feed roller 2 and the friction member 4 start to rotate in mutually opposite directions substantially at the same time. At this time, the rotational peripheral surfaces of the paper feed roller 2 and the friction member 4 are positioned so as to be lower than the uppermost position of the recording paper 3 by d. Therefore, the paper feed roller 2 and the friction member 4 push the recording paper 3 downward by d and are brought into pressure contact with the paper surface. (FIG. 3) The timing when the friction member 4 comes into pressure contact with the paper surface is
It may be after the paper feed roller 2 is in pressure contact with the paper surface. Along with this, the pressing claw 13 (14) also moves downward by d. When the rotation of the paper feed roller 2 and the friction member 4 is advanced, the recording paper 3 between the paper feed roller 2 and the friction member 4 rises upward,
A flexure is formed. Then, the edge of the uppermost recording paper 3 is separated from the pressing claw 13 (14). (FIG. 3) When the paper feed roller 2 and the friction member 4 are further rotated,
The peripheral portion 4a of the friction member 4 is separated from the paper surface of the recording paper 3,
It acts to wind this up against the flexure. When the peripheral portion 4a of the friction member 4 is separated from the paper surface of the recording paper 3 (Fig. 4), the recording paper 3 returns to the restoring direction (arrow direction in Fig. 4) by its own elastic force. (FIG. 4) At this time, the air inside the flexure is pushed out of the recording paper 3, so that the edge of the recording paper 3 is lifted by the wind pressure and goes over the pressing claws 13 (14) to cause the feed roller pair 5 to move. Smoothly delivered to the nip. Since both the paper feed roller 2 and the friction member 4 are controlled by the drive source 7 to make one rotation, they stop at the first position state (FIG. 2) after one rotation.

In order to separate the recording paper and guide it to the feed roller pair 5, the amount of deflection for causing the recording paper 3 to generate a predetermined elastic force and the edge of the recording paper 3 when the recording paper starts to return. It is important to set the distance e from the tip of the pressing claw 13 (14). When the recording paper is a copy paper which is usually used, the flexure height h is about 20 to 50 mm and the distance e is 5 to 20 mm.
A degree is preferable.

As the shape of the friction member 4, since the recording paper 3 crosses the pressing claws 13 (14), a relief portion 4b is provided behind the peripheral edge portion 4a so that the edge of the recording paper 3 is lifted upward. More preferable.

FIG. 6 shows another embodiment. In this embodiment, a bent guide plate 9 is provided between the paper feed roller 2 and the friction member 4. By providing the guide plate 9, it is possible to prevent excessive bending of the recording paper and to reliably feed the recording paper to the feed roller pair. Alternatively, the peripheral edge portion 4a of the friction member 4 may be a high friction member, and the low friction member 4c may be subsequently provided.

[0019]

According to the first and second aspects of the present invention, the apparatus has a simple structure and is inexpensive, and the recording sheet is folded or not fed (misfeed) when it is fed to the image forming apparatus. It is possible to realize paper feeding with very few problems.

[0020]

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which a cassette tray is attached to an image forming apparatus.

FIG. 2 is a cross-sectional view of FIG. 1 viewed from a direction E, showing a main part of the sheet feeding device of the present invention.

FIG. 3 is a diagram showing a paper feeding operation state of the paper feeding device of the present invention.

FIG. 4 is a diagram showing a sheet feeding operation state of the sheet feeding device of the present invention.

5 is a view of the sheet feeding device of the present invention in FIG. 2 as seen from above.

FIG. 6 is a view in which a bent guide plate is provided between a paper feeding roller and a friction member in the paper feeding device of the present invention.

[Explanation of symbols]

1. Image forming apparatus 2. Paper feed roller 3. Recording paper 4. Friction member 5. Feed roller pair 6. Paper feed roller shaft 7. Drive source such as motor 8. Friction member shaft 9. Guide plate 10. Cassette type tray 11. Bottom plate 12. Compression spring 13. Holding claw 14. Holding claw

Claims (2)

[Claims] 1. A paper feeding device for separating the stacked recording papers one by one and supplying the separated recording papers to an image forming apparatus, wherein the stacking recording papers are provided at an edge of the uppermost surface in the feeding direction. Between a claw member provided so as to abut, a rotatable paper feed roller that comes into contact with the uppermost surface of the recording paper and sends out the uppermost recording paper in the feeding direction, and between the claw member and the paper feed roller. A sheet feeding device of an image forming apparatus, which is arranged and has a rotatable friction member that is in contact with the uppermost surface of the recording sheet and applies a force to the uppermost recording sheet in a direction opposite to the feeding direction. 2. The sheet feeding device of the image forming apparatus according to claim 1, further comprising a bent guide plate disposed between the claw member and the sheet feeding roller.