JPH11240633A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder, in which the number of partitems is reduced, and which is capable of fine adjustment of the quantity to be conveyed. SOLUTION: The paper feeder is provided with a pickup roller 2, a feed roller 3 arranged in the downstream in the travelling direction of a paper sheet 1 sent out from the pickup roller 2, and a retard roller 4 installed to face on the outer peripheral surface of the feed roller 3 and abutting on the paper sheet 1 passing through the outer peripheral surface of the feed roller 3 under pressure. Then, the diameter of the feed roller 3 is set larger than that of the pickup roller 2, and the conveyed quantity Ap per one full turn of the pickup roller 2 and the conveyed quantity Af per one full turn of the feed roller 3 satisfy the following expression; 1.00<Ap/Af<=1.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copier (PPC)
The present invention relates to a sheet feeding device used for a facsimile machine and the like.

[0002]

2. Description of the Related Art Conventionally, in a paper feeder used for a copying machine (PPC), a facsimile, or the like, a friction retard (FRR) system (see FIG. 4) or the like is used in order to reliably feed paper one by one. The pad retard (FR) method (see FIG. 5) is employed. In these methods, when two or more sheets of paper 1 are fed by the pickup roller 2 (feeds out the paper 1 set in a cassette or the like [not shown]), in the FRR method, the paper 1 comes into contact with the feed roller 3. Rotate (or stop) in the opposite direction to feed roller 3
The paper 1 is separated into one sheet by the retard roller 4 that is used, and by the retard pad 5 in the FR method.

[0003] In the above-mentioned paper feeder, in order to prevent the paper 1 from being skewed (skewed), a separating unit (in FIG. 4, a feed roller 3 and a retard roller 4 are provided, and in FIG. (Consisting of pad 5)
When the paper 1 enters the paper, a loop 10 is formed slightly (FIG. 6).
), A method of correcting the direction of the leading end of the paper 1 may be adopted. However, when the linear velocity of the pickup roller 2 and that of the feed roller 3 are the same, the speed of the paper 1 at the separation section is reduced by the resistance of the retard roller 4 or the retard pad 5, so that the paper 1 enters the separation section. In this case, the loop 10 generated due to the linear velocity difference between the pickup roller 2 and the separation unit becomes too large, and a paper feed JAM such as a paper break occurs. Therefore, the number of teeth of the drive gear (not shown) of the pickup roller 2 is made larger than the number of teeth of the drive gear (not shown) of the feed roller 3 so that the gear ratio of both drive gears is 1.05 to 1 .18,
In this way, a difference is made between the linear velocities of the two rollers 2 and 3 (that is, the speed of the pickup roller 2 is made slower than the speed of the feed roller 3), so that paper feed JAM such as paper breakage does not occur. Thus, both rollers 2,
Making the linear speed of the rollers 2 and 3 different from each other by the gear ratio of the driving gear 3 is a common technical knowledge in this industry, and the setting of the gear ratio is determined by the operator by feeling. .

[0004]

However, in the above-described paper feeder, it is necessary to prepare two types of drive gears having different numbers of teeth, so that the number of parts is increased. Moreover, the loop amount changes due to the loss of the distance between the pickup roller 2 and the separation unit and the conveyance amount at the separation unit. However, the difference between the linear velocities of the two rollers 2 and 3 depends on the gear ratio of the driving gear. Since it is difficult to finely adjust the transport amount by the attaching method, it is very difficult to always ensure a good loop amount.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a sheet feeder which has a small number of components and can finely adjust a transport amount.

[0006]

In order to achieve the above object, a paper feeder according to the present invention comprises: a pickup roller; a feed roller disposed downstream of the paper fed by the pickup roller in the traveling direction; A pressing member that is in contact with the outer peripheral surface of the feed roller and that presses against the paper passing through the outer peripheral surface of the feed roller in a pressing manner;
The outer diameter of the feed roller is set to be larger than the outer diameter of the pickup roller, and the transport amount Ap per one rotation of the pickup roller and the transport amount Af per one rotation of the feed roller satisfy the following inequality (1). Take the configuration.

[0007]

1.00 <Ap / Af ≦ 1.05 (1)

That is, the present inventors have conducted a series of studies on a sheet feeder having a small number of components and capable of finely adjusting the transport amount. In the course of the research, the linear velocity of both rollers was changed by changing the outer diameter of both rollers, instead of making a difference in the linear velocity of both rollers based on the gear ratio of the drive gear of the pickup roller and the feed roller I imagined that. As a result of further study on this, the present inventors have found that a desired paper feeder can be obtained by satisfying the condition of the above inequality (1), and reached the present invention. Therefore, in the conventional example, two types of driving gears are required, but in the present invention, only one type of driving gear may be used, and the number of types of driving gears can be reduced by one type. In addition, when the outer diameters of both rollers are changed, the change of the outer diameter can be adjusted with high accuracy, so that the conveyance amount can be adjusted more finely than the setting based on the gear ratio of the driving gear.

In the present invention, the transport amount Ap per one rotation of the pickup roller and the transport amount Af per one rotation of the feed roller satisfy the above inequality (1).
In this case, when the paper enters the separation section, an appropriate (slight) loop can be formed, and no JAM or skew occurs. That is, the above-mentioned transport amount ratio A
If p / Af> 1.05, the loop becomes too large, and problems such as broken paper JAM and contact with components on the paper feed path are likely to occur. Also, Ap / Af ≦ 1.0
In the case of 0, a loop is not formed, so that skew easily occurs. In the present invention, the pressing member (the retard roller 4 in FIG. 4, the retard pad 5 in FIG. 5) presses the paper passing through the outer peripheral surface of the feed roller.
Is 50 g or more, and the rotation speed of the pickup roller and the feed roller is 500 m.
This is applied to a sheet feeding device set to m / sec or less. The pickup roller and the feed roller have a coefficient of friction of 1 or more. If these conditions are not satisfied, there is a difference between the theoretical feed amount of the pickup roller and the feed roller and the actual feed amount. In the paper feeder set to such a condition, the transport amount A per rotation of the pickup roller
p is the amount of paper transported during one rotation of the pickup roller, and is equal to the circumference of the pickup roller. Also,
The transport amount Af per one turn of the feed roller is determined by a pressing member (a retard roller or a retard pad in a separation unit).
Is smaller than the circumference of the feed roller due to the loss L (%) due to the resistance of the feed roller, and is calculated by the following equation (2).

[0010]

Af = Df × π × (100−L) / 100 (2) Df: outer diameter of feed roller

The outer diameter ratio between the outer diameter Dp of the pickup roller and the outer diameter Df of the feed roller used in the present invention varies depending on the value of L, the paper type, the structure of the paper transport path, and the like. The outer diameter ratio with the best sheet feeding performance under the conditions is selected. That is, when L is small, the outer diameter ratio Dp / Df of both rollers may be large (see Table 1 below), but when L is large, the outer diameter ratio Dp / Df of both rollers is large.
Df must be reduced (see Table 3 below). Even if the rotation speeds of both rollers are different, Ap / Af does not change, so that the rotation speeds of both rollers are 500 mm /
sec or less, for all speed paper feeders,
The above conditions apply.

In the present invention, when the feed roller is composed of a shaft and an elastic rubber layer formed on the outer peripheral surface of the shaft, an elastic rubber is formed on the shaft made of a synthetic resin material or the like. The elastic rubber layer can be manufactured by polishing and finishing the surface of the elastic rubber layer for the purpose of increasing the dimensional accuracy and the like, in which the layer is press-fitted into an external fitting shape. In this case, by controlling the outer diameter of the vulcanized rubber and the allowance for polishing in the polishing step, the outer diameter of the elastic rubber layer can be easily adjusted to an optimum set value to produce the elastic rubber layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the sheet feeding device of the present invention. In the drawing, reference numeral 2 denotes a cassette or the like (not shown)
Is a pickup roller (outer diameter Dp = 20 mm) for feeding out the paper 1 set in the printer. Reference numeral 3 denotes a feed roller (outer diameter D) formed to have a larger diameter than the pickup roller 2.
f = 21 mm), and is disposed on the downstream side in the traveling direction of the paper 1 sent out by the pickup roller 2. Reference numeral 4 denotes a retard roller in a stopped state in contact with the feed roller 3. The feed roller 3 and the retard roller 4 constitute a separation section. Reference numeral 6 denotes a spring for urging the retard roller 4 toward the feed roller 3.

As shown in FIGS. 2 and 3, each of the rollers 2, 3, and 4 has a cylindrical iron core 7 and a cylindrical polyacetal shaft formed on the outer peripheral surface of the core 7. 8 and a cylindrical ethylene-propylene-diene copolymer (EDP) provided by press-fitting on the outer peripheral surface of the core shaft 8.
M) made of an elastic rubber layer 9, and a shaft is constituted by the core metal 7 and the core shaft 8. The surface of the elastic rubber layer 9 is polished in order to increase the accuracy of the outer diameter.

In such an embodiment, the feed speed of the paper 1 is always set to a constant speed, and the loss L due to the resistance of the retard roller 4 is set to 5%. The rotation speed of the pickup roller 2 and the feed roller 3 is set to 500 mm / sec or less, and the friction coefficient is set to 1 or more. Further, it is set so that a load of 50 g or more is applied to the paper 1 by the elastic pressing force of the spring 6.

In this embodiment, as shown in Example 2 in Table 1 below, the transport amount Ap of the pickup roller 2
The ratio Ap / Af of the feed amount Af of the feed roller 3 is 1.003. And in this one, paper folding JA
M and skew do not occur. Further, in this embodiment, since the linear velocities of the rollers 2 and 3 are made different by changing the outer diameters of the rollers 2 and 3, only one type of driving gear may be used. Moreover, since the two rollers 2 and 3 are formed by press-fitting the elastic rubber layer 9 on the outer peripheral surface of the shaft body, the outer diameters of the two rollers 2 and 3 can be finely controlled, and the fine transport amount can be reduced. Adjustment is possible.

[0018]

Embodiments 1 and 2 and Comparative Examples 1 to 3 In the paper feeder shown in FIG.
mm, and the loss L of the transport amount at the separation section due to the resistance of the retard roller 4 was set to 5%. Then, the outer diameter Df of the feed roller 3 is set to 19.5 mm, 20 mm, and 2 mm.
0.5 mm, 21 mm, and 21.5 mm, respectively, and Df / Dp, Ap, Af, Ap /
The value of Af was calculated, and the occurrence of JAM (paper break) and the occurrence of skew (oblique feed) were checked to determine whether or not use was possible. The results are shown in Table 1 below.

[0019]

Examples 3 and 4 and Comparative Examples 4 to 6 In the paper feeder shown in FIG. 1, the outer diameter Dp was set to 20 mm, and the loss L of the transport amount was set to 10%. The outer diameter Df is 20.5
mm, 21mm, 21.5mm, 22mm, 22.5m
m, and Table 2 below was created in the same manner as in Table 1.

[0020]

Examples 5 to 7 and Comparative Examples 7 and 8 In the paper feeder shown in FIG. 1, the outer diameter Dp was set to 20 mm, and the loss L of the transport amount was set to 15%. And the outer diameter Dp is 22m
m, 22.5 mm, 23 mm, 23.5 mm, 24 mm
Table 3 below was prepared in the same manner as in Table 1.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

As is clear from Tables 1 to 3,
If 1.00 <Ap / Af ≦ 1.05, JA
It can be seen that there is no occurrence of M and no skew, and it can be used. On the other hand, when Ap / Af> 1.05, JAM such as paper breakage or paper jam is likely to occur, while Ap
In the case of /Af≦1.00, it can be seen that skew easily occurs. When L is small, Dp / Df may be large. However, when L is large, Dp / Df needs to be small.

In the above embodiment, the material of the elastic rubber layer 9 of each of the rollers 2, 3 and 4 is EPDM.
However, the present invention is not limited to this. Various rubbers such as olefin-based rubber and natural rubber, no solex, urethane rubber, and other rubber materials generally used as rollers, or resins other than rubber, such as rubber, are used. Materials are used. Further, in the above embodiment, the shaft is constituted by the core metal 7 and the core shaft 8, but the shaft may be constituted by the core metal 7 or the core shaft 8 alone.

[0026]

As described above, according to the paper feeding apparatus of the present invention, two types of driving gears are required in the conventional example, but in the present invention, only one type of driving gear is required, and One kind of gear can be reduced. In addition, when the outer diameters of both rollers are changed, the change of the outer diameter can be adjusted with high accuracy, so that the conveyance amount can be adjusted more finely than the setting based on the gear ratio of the driving gear.

Further, in the present invention, the transport amount Ap per rotation of the pickup roller and the transport amount Af per rotation of the feed roller satisfy the above inequality (1).
In this case, when the paper enters the separation section, an appropriate (slight) loop can be formed, and no JAM or skew occurs. That is, the above-mentioned transport amount ratio A
If p / Af> 1.05, the loop becomes too large, and problems such as broken paper JAM and contact with components on the paper feed path are likely to occur. Also, Ap / Af ≦ 1.0
In the case of 0, a loop is not formed, so that skew easily occurs.

In the present invention, when the feed roller comprises a shaft and an elastic rubber layer formed on the outer peripheral surface of the shaft, the shaft made of a synthetic resin material or the like has an elastic rubber. The elastic rubber layer can be manufactured by polishing and finishing the surface of the elastic rubber layer for the purpose of increasing the dimensional accuracy and the like, in which the layer is press-fitted into an external fitting shape. For this reason, by controlling the outer diameter of the vulcanized rubber and the polishing allowance in the polishing step, the outer diameter of the elastic rubber layer can be easily adjusted to the optimum set value to produce the elastic rubber layer.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a sheet feeding device of the present invention.

FIG. 2 is a perspective view of a roller used in the paper feeding device.

FIG. 3 is a sectional view of the roller.

FIG. 4 is an explanatory diagram of a conventional sheet feeding device.

FIG. 5 is an explanatory diagram of another conventional sheet feeding device.

FIG. 6 is an explanatory diagram of a loop.

[Explanation of symbols]

 1 paper 2 pickup roller 3 feed roller 4 retard roller

Claims (2)

[Claims] 1. A pickup roller, a feed roller disposed on the downstream side in the traveling direction of paper fed by the pickup roller, and a paper passing through the outer peripheral surface of the feed roller in contact with the outer peripheral surface of the feed roller. A pressing member that comes into contact with the pressing roller, the outer diameter of the feed roller is set to be larger than the outer diameter of the pickup roller, and the transport amount Ap per one rotation of the pickup roller and the transport amount Af per one rotation of the feed roller are different. A sheet feeding device characterized by satisfying the following inequality (1). 1.00 <Ap / Af ≦ 1.05 (1) 2. The sheet feeding device according to claim 1, wherein the feed roller includes a shaft and an elastic rubber layer formed on an outer peripheral surface of the shaft.