JPH08119472A - Paper sheet feeding device - Google Patents

Abstract

PURPOSE: To feed both wide and narrow sheets at optimum sheet feeding pressures, respectively, by a single sheet feeding roller by providing an energizing means to press the sheet feeding roller elastically downward only when the wide sheets are set in a sheet feeding cassette. CONSTITUTION: Leaf springs 9 are installed on the downstream side of a sheet feeding route at positions symmetrical laterally with respect to the axis center part of of a sheet feeding roller 5. Also the leaf springs 9 are arranged on the inner side of the lateral end parts of a large-sized sheet feeding cassette 1 in which large-sized sheets are stored, and the optimum sheet feeding pressure is energized automatically to the large-sized sheets 2 by the leaf springs 9. On the other hand, when a small-sized sheet feeding cassette in which small-sized sheets are stored is set up, the leaf springs 9 are positioned on the outside of the sheet feeding cassette and applies a sheet feeding pressure of only the self weight of the sheet feeding roller 5 to the sheets. Thus double sheet feeding by excess sheet feeding pressure is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of pushing a stacked sheet up to a predetermined height by mounting a sheet feeding cassette containing a stacked sheet placed on a bottom plate in the main body of the apparatus, and the uppermost sheet of the stacked sheet. The present invention relates to a sheet feeding device in which a sheet feeding rotary member is brought into contact with a sheet by its own weight and the uppermost sheet is sequentially fed by rotation of the sheet feeding rotary member.

[0002]

2. Description of the Related Art A sheet feeding device of the above type is well known, and is mainly provided for feeding a transfer sheet in a printer, a copying machine, a facsimile, a printing machine or the like. In this type of conventional sheet feeding device, as shown in FIG. 5, a sheet 51 stored in a sheet feeding cassette 50 is urged upward by a tray raising device 52 driven by a driving unit (not shown), and its uppermost sheet surface. By the paper surface detection sensor whose height is not shown,
It is controlled to be maintained at a predetermined height.

On the other hand, a paper feed roller 53, which is a paper feed rotating member, is rotatably supported by a paper feed arm 54 and is rotationally driven by a driving means (not shown). This paper feed roller 53
Is in contact with the sheet 51 stacked in the sheet feeding cassette 50 due to its own weight, and thus the sheet feeding pressure depends on the weight W of the sheet feeding roller 53 that is initially determined.

In the sheet feeding apparatus configured as described above, there are many apparatuses in which sheets having different sheet widths, for example, B5 size to A1 size, must be fed by the same feeding roller. This type of sheet feeding device shows that it can handle sheets of any sheet width with the same sheet feeding pressure. For example, when the sheet feeding width is set to an optimum sheet feeding pressure, When feeding a sheet having a small sheet width, an excessive sheet feeding pressure is generated, which causes a problem that double feeding frequently occurs. On the other hand, when the optimum sheet feeding pressure is set for a sheet having a small sheet width, there is a problem in that when a wide sheet is fed, non-feeding occurs due to insufficient sheet feeding pressure.

Therefore, in order to prevent such a problem,
The weight of the paper feed roller is set to be equal to or greater than the weight of the largest sheet that can be fed, and the elastic force is set according to the size of the sheets loaded in the paper feed cassette. A paper feeding device in which an elastic member for pushing up a roller is provided in a paper feeding cassette has already been proposed. In this paper feeding device, the elastic member corresponding to the size of the sheet pushes up the paper feeding roller, so that the paper feeding pressure can be set for each size of the sheet.

[0006]

However, in the above-mentioned paper feeding device, the weight of the paper feeding roller is equal to or more than the weight at which the largest sheet that can be fed can be fed. When the elastic force of the elastic member that pushes up the roller shaft of the paper feed roller is reduced due to a change with time or the like, there is a possibility that an excessive paper feed pressure occurs and double feeding occurs. In addition, double-feeding and non-feeding have relatively few post-processing and side effects after non-feeding occurs, but when double-feeding wastes the sheets and the double-feeding sheet becomes a jam, the jam sheet is removed. Requires action. Therefore, the paper feeding pressure tends to be a set value close to the non-feeding side, but in the above-described paper feeding device, double feeding is likely to occur. Further, in the above-described paper feeding device, since the elastic member is provided for each cassette, the number of parts increases and the cost becomes high.

The present invention solves the above-mentioned conventional problems, and provides a sheet feeding device capable of feeding a wide sheet and a sheet having a small sheet width at optimum sheet feeding pressures with a single sheet feeding roller. Is intended.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a stacking sheet to a predetermined size by mounting a paper feed cassette storing the stacking sheet on a bottom plate in the main body of the apparatus. In the sheet feeding device that is pushed up to the height, the sheet feeding rotating body is brought into contact with the uppermost sheet of the stacked sheets by its own weight, and the sheet is sequentially fed from the uppermost sheet by the rotation of the sheet feeding rotating body. It is characterized in that a pressing means for urging an elastic force for pressing down the sheet feeding rotary member in the direction of contacting the sheet with a pressing force according to the size of the sheet thus formed is provided.

Further, in order to achieve the above object, the present invention is characterized in that the pressing force by the pressing means is generated by mounting the paper feeding cassette on the paper feeding device main body.

[0010]

In the sheet feeding device of the present invention, the sheet feeding pressure corresponding to the sheet having the predetermined small sheet width is applied to the portion corresponding to the sheet feeding roller only when the wide sheet is set in the sheet feeding cassette. The attached sheet feeding pressure amplifying device urges the sheet feeding roller contacting the sheet set in the sheet feeding cassette downward to increase the sheet feeding pressure to a desired sheet feeding pressure. As a result, it is possible to feed the wide paper and the small-width sheet at the optimum paper feeding pressure.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 are explanatory views showing an embodiment of the present invention. In FIGS. 1 and 2, reference numeral 1 is a sheet feeding cassette, 2 is a sheet accommodated in the sheet feeding cassette 1, and the sheets are stacked and placed on the cassette bottom plate 3.
Further, reference numeral 4 denotes a sheet feeding device main body, and the sheet feeding device main body 4
Is a sheet feeding roller 5 as a sheet feeding rotating member that sequentially feeds the uppermost sheet of the stacking sheet 2, a bottom plate raising device 7 that raises the uppermost sheet to a predetermined height via the cassette bottom plate 3, and the attached sheet feeding device. It has a stopper 8 for stopping the cassette 1 at a predetermined position. The paper feed roller 5 is rotatably mounted on a paper feed arm 6 rotatably supported by a side plate (not shown) of the paper feed device main body 4, and is rotationally driven clockwise by a driving means (not shown).

The paper feeding device is provided in a device capable of forming images on sheets of various sizes, and in this example, it is a device that uses sheets of different sheet widths from B5 size to A1 size. The paper feed cassette 1 stores a small paper feed cassette 1S for storing small sheets 2S of B5 size to A3 size shown in FIG. 4, and a large pay for storing a large sheet 2B of B3 size to A1 size shown in FIG. The paper cassette 1B is divided into two sizes. Therefore, the sheet feeding device of this embodiment is set so that when the sheet feeding roller 5 is placed on the accumulation sheet 2 by its own weight, the sheet feeding pressure P corresponds to the small sheet 2S. That is, the sheet feeding pressure P based on the sheet feeding roller weight W of the sheet feeding roller 5 is set to the optimum pressure for feeding the small sheet 2S.

In the paper feeding device according to the present invention, a pair of leaf springs 9 as pressing means are provided on the downstream side in the paper feeding direction symmetrically with respect to the axial center portion C of the paper feeding roller 5. The leaf spring 9 is located outside the widthwise end of the small sheet feeding cassette 1S containing the small sheets 2S and inside the widthwise end of the large sheet feeding cassette 1B containing the large sheets 2B. It is arranged. The leaf spring 9 is formed in an L-shaped lateral shape, one end of which is an abutting portion 9a against which the paper feeding cassette 1 is abutted, and the other end of which is the shaft 5 of the paper feeding roller 5.
It is a pressing portion 9b that presses a from above. And
The leaf spring 9 is swingably attached via a shaft 12 to a support member 11 attached to a bottom plate 10 of the sheet feeding device main body 4, and in this case, the pressing portion 9b is always the roller shaft 5 of the sheet feeding roller 5.
is abutted on a.

The sheet feeding device having the above-described structure is based on the large sheet feeding cassette 1
When B is set at the proper position in the sheet feeding device body 4, the large sheet feeding cassette 1B is abutted against the stopper 8 and set at the regular position. At this time, the front wall portion 13 in the sheet feeding direction of the large sheet feeding cassette 1B pushes forward against the abutting portion 9a of the leaf spring 9, and the leaf spring 9 is rotated about the shaft 12 in the clockwise direction in FIG. I try to force it. On the other hand, when the large sheet 2B stored in the large sheet feeding cassette 1B is raised by the bottom plate raising device 7 and reaches a predetermined height, the pressing portion 9b of the leaf spring 9 is pressed against the roller shaft 5a of the sheet feeding roller 5. Leaf spring 9
Is elastically deformed, and a pushing-down force F that pushes the roller shaft 5 of the paper feed roller 5 downward is generated. At this time, the sum of the pushing-down force F for pushing down the roller shaft 5a of the sheet feeding roller 5 and the weight W of the sheet feeding roller becomes the sheet feeding pressure P, and the pushing down force F depends on the thickness of the leaf spring 9, the material, and the shape. Since it can be set arbitrarily,
It is possible to make the paper feed pressure P that is the sum of the pushing-down force F and the paper feed roller weight W optimal for the large sheet 2B to be fed.

Also, a small sheet feeding cassette 1S for small sheets 2S.
Is set to the proper position on the main body 4 of the paper feeder,
The small sheet 2S set in the small sheet feeding cassette 1S of the small sheet 2S is lifted up to a predetermined height by the tray lifting device 7. At this time, since the leaf spring 9 is positioned outside the widthwise end of the small sheet feeding cassette 1S for the small sheet 2S, it does not contact the small sheet feeding cassette 1S for the small sheet 2S. Therefore, the leaf spring 9 is not in the tensioned state, and the pushing down force F that pushes down the roller shaft 5a of the sheet feeding roller 5 is not generated. As a result, the small sheet 2S stored in the sheet feeding cassette 1S is fed by the sheet feeding pressure of only the weight of the sheet feeding roller 5.

Thus, when the large paper feed cassette 1B is set in the paper feed device main body 4, the leaf spring 9 automatically sets the optimum paper feed pressure for the large sheet 2B, and the small paper feed cassette 1S is set in the paper feed device main body 4. When the sheet is set at the regular position, the feeding pressure is only the own weight of the feeding roller 5 which is optimum for the small sheet 2S. Moreover, even when the elastic action of the leaf spring 9 is not exerted, the sheet feeding pressure is set to a value close to the non-feeding side, so that there is no problem of double feeding in which post-processing is troublesome.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, in the above-described embodiment, two types of sheet feeding pressures, that is, the small sheet feeding cassette 1S and the large sheet feeding cassette 1B are set, but the leaf spring 9 is in contact with the front wall portion 13 in the sheet feeding direction of all the sheet feeding cassettes 1. By adjusting the overhanging width or the width of the depression of the front wall portion 13 in the sheet feeding direction, the pushing-down force F can be changed steplessly from zero to obtain the sheet feeding pressure P corresponding to each size. You can in this case,
It can also be applied to a paper feeding device of a type in which all sheets are stored in a paper feeding cassette of a single size.

Further, although the leaf spring is used as the elastic member in the above embodiment, it is needless to say that a rubber material having the same property can be used.

[0020]

According to the first aspect of the present invention, it is possible to set the optimum sheet feeding pressure according to the size and thickness of the sheet with a single sheet feeding roller, and the elastic force of the pressing means is reduced. Even in such a case, the paper feeding pressure is reduced, and since the paper feeding pressure approaches the non-feeding side, it is advantageous that the double feeding having a large side effect does not easily occur.

According to the second aspect, since the paper feed pressure increasing pressure is automatically generated by mounting the paper feed cassette, it is possible to change the paper feed pressure with a simple structure without requiring any other power source. Furthermore, when the paper feed cassette is not attached, the load is not applied to the paper feed pressure amplifying device, the life of parts is extended, fluctuations in the paper feed pressure increase are suppressed, and it is possible to constantly increase the paper feed pressure. .

[Brief description of drawings]

FIG. 1 is a side view illustrating a state before a paper feeding cassette of a paper feeding device according to the present invention is set to a regular position.

FIG. 2 is a side view illustrating a state in which the paper feed cassette is set at a regular position.

FIG. 3 is a perspective view showing a state in which a large paper feed cassette is set.

FIG. 4 is a perspective view showing a state in which a small paper feed cassette is set.

FIG. 5 is an explanatory diagram showing a conventional paper feeding device.

[Explanation of symbols]

 1 Paper feeding cassette 1B Large paper feeding cassette 1S Small paper feeding cassette 2 Sheet 2B Large sheet 2S Small sheet 4 Paper feeding device body 5 Paper feeding roller 7 Tray lifting device 9 Leaf spring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 1/00 108 Z

Claims (2)

[Claims] 1. A stacking sheet placed on a bottom plate is attached to a main body of the apparatus to push the stacking sheet up to a predetermined height, and a sheet feeding rotary member is placed on the uppermost sheet of the stacking sheet. In the paper feeding device that is abutted by its own weight and sequentially feeds the uppermost sheet by rotation of the paper feeding rotator, the paper feeding rotation is performed by pressing force according to the size of the sheets stored in the paper feeding cassette. A sheet feeding device, comprising: a pressing unit that applies an elastic force that pushes down a body in a direction of abutting against a sheet. 2. The paper feeding device according to claim 1, wherein the pressing force of the pressing means is generated by mounting the paper feeding cassette on the paper feeding device main body.