JPH0253343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper sheet feeding device that is applied to various printers, and more particularly, to a paper sheet feeding device that separates and conveys multiple sheets of paper. This is related to.

[Conventional technology]

In recent years, there has been a strong call for streamlining office work, and various office automation devices have been developed. BACKGROUND OF THE INVENTION In office work, the work of recording necessary information on forms such as slips is enormous, and various printers have been commercialized as a means of saving labor.

When using conventional printers, two methods are used: one is to manually insert forms one by one, and the other is to automatically feed continuous forms with feeding holes in the paper using a tractor. It's here. Recently, there has been a demand for automatic feeding of pre-cut forms.

Examples of devices that automatically feed sheets include copying machines and optical character readers (OCR).

FIGS. 1 and 2 show typical examples of friction type separation mechanisms used in these devices.

That is, the sheet group 1 is stacked and stored on the loading table 3 pushed up by the spring 2, and the sheet group 1
The topmost paper sheet 1a is lightly abutted against a feed-out roller 4, and when the feed-out roller 4 rotates in the direction of the arrow in the figure, the topmost sheet 1a is fed out. The paper sheet 1a fed out in this manner is transported by a separation feeding means consisting of a feeding roller 5, a friction member 6, and a spring 17 as a biasing means, and a conveyance means consisting of a pair of facing conveyance rollers 11 and 11'. The paper is separated into individual sheets and sent backwards. The rollers 4, 5, 11 are connected to motors 7, 8 via belts 9, 10, 12, and are rotated by these motors 7, 8 so as to convey the sheet 1a in the same direction.

Now, when the motor 7 is driven, the feeding roller 4
The uppermost sheet 1a is sent out in cooperation with the feed roller 5. The sheet of paper is moved to the left in the figure by the frictional force between the friction member 6 pressed against the feed roller 5 via the spring 17 and the feed roller 5. Only the uppermost sheet 1a that is stopped and comes into contact with the feed roller 4 and the feed roller 5 is conveyed downstream. As a result, the stacked sheet group 1 is separated one by one, held by the conveyance rollers 11, 11', and sent rearward.

In the conventional apparatus shown in FIGS. 1 and 2, the shaft 13 of the feed roller 4 and the shaft 14 of the feed roller 5 are connected by a transmission means such as a belt, and the first sheet 1a is transferred to the transport roller. 11, 11', the clutch 15 is connected to the shafts 13, 14 in order to remove the driving force on these shafts 13, 14.
14 and the motor 7. 16 indicates a guide for paper sheets.

[Problem to be solved by the invention]

On the other hand, among the forms printed by printers, multi-part forms (hereinafter referred to as multi-part forms) that print multiple forms at the same time occupy the main part, and their configuration uses non-carbon paper. There are various types such as carbon, medium carbon, and back carbon. What they all have in common is that the paper used is extremely thin in terms of printing quality because many copies are made at the same time.

If such a multi-copy paper is automatically separated and taken out one by one from a stacking table on which a plurality of copies are stacked and conveyed, a problem as shown in FIG. 3 occurs.

Now, there are many copies of paper piled up on the stacking table.
Among them, the uppermost multi-copy sheet A is fed out by a feeding roller 4, and separated from the lower multi-copy sheets R, H, etc. between the feed roller 5 and the friction member 6. Thereafter, the feed roller 5 is fed by the frictional force to the downstream conveyance rollers 11, 11', where it is held between the pair of rollers 11, 11' and carried out.

However, at this time, in the multi-sheet sheet I which is held at the separation force application point 20 by the feed roller 5 and the friction member 6, the first sheet from above I-1 is not affected by the feed roller 5. Although a conveying force is applied, the conveying force is not applied to the lowest n-th sheet of paper I-n that is in contact with the friction member 6, and on the contrary, a force is applied in a direction that prevents the sheet from moving. Therefore, if the force of the spring 17 is strong or if the friction coefficient of the friction member 6 is large, the lower sheet of paper E-n will not move and only the uppermost sheet of paper E-1 will be sent out. . If this situation continues, as shown in FIG. 3, only the sheets of the multi-copy sheet 1 that are in contact with the feed roller 5 will be fed, and a jam will occur between the feed roller 5 and the conveyance roller 11. Put it away.

The jamming phenomenon described above occurs when the leading edge 2 of the multi-copy paper 1
1 is glued, and the force acting on the first sheet of paper E-1 on the upper surface by the feed roller 5 is applied to the glued portion 21.
This occurs because the force is transmitted to the paper sheet below through the paper, and as the paper sheet becomes thinner, the sheet buckles and the force is not transmitted downwards sufficiently. To solve this problem, the lower surface of sheet I-1 and the upper surface of the next sheet E-2, and the lower surface of sheet E-2 and the next sheet E-3 are
By increasing the friction coefficient of the surface where sheets come into contact, such as the top surface, the conveying force can be sufficiently transmitted from the top surface to the bottom surface of multiple sheets at the separation force application point 20, and multiple sheets can be set. It can be transported as is. However, in reality, the friction coefficient of the friction member 6 for separating multiple copies of paper one by one cannot be made very small. Furthermore, since various chemical treatments are applied to the surfaces of sheets of paper used for copying, the coefficient of friction between each sheet of paper is reduced. Therefore, it is difficult to prevent misalignment between sheets by increasing the coefficient of friction between them.

FIG. 4 shows the buckling characteristics of paper sheets. As shown in Figure 4a, a force is applied to the position l from the tip of the sheet to cause the sheet to buckle from the state shown by the solid line to the state shown by the broken line, and the reaction force P at the time of buckling is measured. This results in a buckling characteristic curve as shown in Figure 4b.
In other words, this buckling reaction force P corresponds to the upper limit of the feeding force F that can be applied to the position l from the leading edge of the sheet under the condition that the uppermost sheet E-1 is not buckled.

As shown in Figure b, if we take the length l on the horizontal axis and the buckling reaction force P on the vertical axis, the smaller l is, the more the buckling reaction force P
It turns out that it is possible to make the value larger. Figure 4b
This is the result of determining the buckling characteristics of 35Kg paper, which is the most commonly used multi-sheet paper. Looking at it from a different perspective, if the feeding force F applied to the paper sheet is made minute, the critical length l that causes buckling can be made larger and larger, as shown by the solid line, but in order to convey the paper sheet, there is a Since a feeding force F greater than this value is required, a limit naturally occurs on the maximum value of l.

Now, returning to FIG. 3 again and considering the force acting on the sheet of paper, we can see that the force acting on the sheet of paper at the lowest position is
A sufficiently large feeding force F must be transmitted from the feed roller 5 to the paper sheet gluing section 21 via the uppermost paper sheet E-1 to counter the resistance force R applied to n. I know it won't happen. At this time, if the paper sheet I-1 is a thick paper sheet and the buckling reaction force P can be large, the relationship F>R can be satisfied. On the other hand, when paper sheets used in multiple copies become thinner, the buckling reaction force P becomes smaller as shown in FIG. 4, and the relationship F>R is no longer necessarily satisfied.

The present invention has been made in view of the above points, and an object of the present invention is to provide a highly reliable paper sheet feeding device that can transport multiple sheets of thin paper to a post-processing process without jamming them. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention provides a loading platform 3
Separating and feeding means 5 and 6 for separating and feeding the multi-sheet paper 1 stacked and stored on top and having the leading ends 21 of a plurality of sheets fixed to each other into portions, and downstream of the separating and feeding means. Conveying means 11, 1 for holding and conveying multiple sheets separated one by one by the separating and feeding means;
1', the separating feeding means 5, 6 and the conveying means 11,
11' is the buckling limit length of the paper sheet determined from the buckling characteristic curve of the paper sheet (Fig. 4b) by the feeding force F applied to the multiple sheets by the separating and feeding means. l It is characterized by being set smaller than ₂ .

[Effect]

With this configuration, according to the present invention, the above object is achieved through the following actions.

In other words, the buckling characteristic curve of the paper sheet illustrated in _FIG . be. Therefore, when the necessary feeding force F is determined, the buckling limit length l ₁ corresponding to the feeding force F (=buckling reaction force P') can be calculated from the buckling characteristic curve of the sheet. separation feeding means 5, 6 and conveying means 1
1 and 11' is set smaller than l ₁ , the uppermost sheet fed out by the feeding force F applied by the separating feeding means can be The leading end 21 of the paper 1 is the conveying means 11,
11', multiple copies of paper can be conveyed to the post-processing process without jamming.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The distance L between the contact point 20 between the feed roller 5 and the friction member 6, that is, the point that applies separation force and conveyance force to the sheet, and the sheet holding point 22 by the conveyance rollers 11 and 11' located downstream thereof is , the topmost paper leaf
1 is fed out by the feed roller 5, the length is such that the sheet does not buckle.

If we review this with reference to FIG. 4b, we can see that practically speaking, the L dimension may be made smaller than the length l ₂ at which the linear approximation (broken line) of the characteristic curve intersects the horizontal axis.

For example, in the case of a multi-copy paper made of 35Kg paper, which is commonly used in the past, this L dimension should be approximately
It should be 50mm or less.

Now, in Fig. 5, if the dimension L is set to 30 mm, the buckling reaction force P' is approximately 150 gf from Fig. 4, so the pressing force is adjusted by the spring 17 that presses the friction member 6 against the feed roller 5. However, by setting the friction member 6 so that the resistance applied to the bottom surface of the paper sheets does not exceed 150gf, it is possible to transport the sheets without jamming or misalignment of the sheets. This situation can be avoided.

It is clear that in the case of multiple sheets made of thin paper of 35 kg or less, the allowable dimension L becomes smaller because the characteristic curve in FIG. 4 moves toward the origin.

〔Effect of the invention〕

As detailed above, according to the present invention, the point 20 where the feeding force F and the resistance force R act simultaneously on the paper sheet
and the distance between the sheet holding point 22 of the conveying roller which is located downstream and grips and conveys the fed sheet.
Since the setting is made within a range that does not cause buckling of paper sheets, when multiple sheets of paper are separated and conveyed, only the sheets of paper that are in contact with the feed roller are fed out, causing the multiple sheets of paper to form a bag-like shape, or the upper and lower portions It is possible to avoid paper sheets being conveyed with misalignment or jams occurring between the feed roller and the conveyance roller, and it is possible to automatically feed multiple sheets, which is difficult to achieve with conventional separation mechanisms. It becomes possible.

In the embodiment, an example is given in which multiple sheets of paper are separated and conveyed one by one from above, but it goes without saying that the present invention can also be applied to a structure in which sheets of paper are separated and conveyed sequentially from below.

Furthermore, although an example has been shown in which a friction member is used as a means for applying separation resistance to paper sheets, for example, a vacuum suction means is provided in place of the friction member 6, and by sucking the paper sheets, resistance is applied to the conveyance thereof. Needless to say, the present invention can also be applied to devices having such a configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional sheet feeding device, FIGS. 2 and 3 are diagrams showing the sheet conveying state of the conventional sheet feeding device, and FIG. 4a shows how the sheet is buckled. FIG. 4b is a diagram showing the buckling characteristic curve of paper sheets, and FIG. 5 is a longitudinal sectional view of the paper sheet feeding device of the present invention. 4... Feeding roller, 5... Feeding roller, 6... Friction member, 11, 11'... Conveyance roller.

Claims (1)

[Scope of Claims] 1. Separation and feeding means 5, 6 for separating and feeding the multi-sheet paper 1 stacked and stored on the loading table 3 and having the tip ends 21 of the plurality of paper sheets fixed to each part one by one. and conveying means 11, 11' downstream of the separating and feeding means, which grips and conveys multiple sheets separated into portions by the separating and feeding means. In the feeding device, the separating feeding means 5, 6 and the conveying means 11,
11' is the buckling limit length of the paper sheet determined from the buckling characteristic curve of the paper sheet (Fig. 4b) by the feeding force F applied to the multiple sheets by the separating and feeding means. l A paper sheet feeding device characterized by being set smaller than ₁ . 2. In the case of multiple sheets of 35 kg paper, the distance L between the separating and feeding means 5, 6 and the conveying means 11, 11' is approximately 50 mm or less, according to claim 1. sheet feeding device. 3. The separating and feeding means includes a feed roller 5 that applies a feeding force F to the multiple sheets, and a friction member 6 that is pressed against the feed roller 5 by a biasing means 17 and separates the multiple sheets one part at a time. A sheet feeding device according to claim 1 or 2, characterized in that: