JP3502719B2 - Paper feeder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction separating roller type sheet feeding device for separating and feeding double fed sheets.

[0002]

2. Description of the Related Art Conventionally, various types of sheet feeding devices have been proposed and put to practical use so as to prevent double feeding of sheets. One of such sheet feeding devices is a feed roller that is rotationally driven in the sheet feeding direction, and a reverse roller that is pressed against the outer peripheral surface of the feed roller and applies a predetermined torque in the direction opposite to the sheet feeding direction. There is known a sheet feeding device of a friction separation roller type having a sheet feeding method. The structure of the friction separating roller type sheet feeding device will be described with reference to FIG. A pickup roller 3 is provided above the cassette 2 in which the sheets 1 are stored to sequentially feed the sheets 1 stored in the cassette 2 from the topmost sheet in the sheet feeding direction. A feed roller 4 rotatably driven in the sheet feeding direction and a reverse roller 5 pressed against the outer peripheral surface of the feed roller 4 are arranged downstream of the sheet 1 fed by the pickup roller 3 in the sheet feeding direction. . A torque limiter 6 is connected to the reverse roller 5, and a predetermined torque (paper returning force) is applied from the torque limiter 6 to the reverse roller 5 in a direction opposite to the paper feeding direction.

In this paper feeding device, the difference between the frictional force between the feed roller 4 and the paper 1 and the frictional force between the papers 1 and the paper feeding direction given to the reverse roller 5 by these frictional forces. And the torque applied in the reverse direction to the reverse roller 5 from the torque limiter 6 are utilized to separate and feed the double-fed sheets 1.

Specifically, when two or more sheets of paper 1 enter between the feed roller 4 and the reverse roller 5, the torque limiter 6 applies a reverse direction to the paper feed direction applied to the reverse roller 5. The torque exceeds the torque applied from the feed roller 4 to the reverse roller 5 in the paper feed direction, the reverse roller 5 rotates in the direction opposite to the paper feed direction, and only the paper 1 in contact with the feed roller 4 is fed. Paper 1 is fed in the direction
Double feed is prevented.

On the other hand, when one sheet of paper 1 is inserted between the feed roller 4 and the reverse roller 5, the torque in the paper feeding direction applied from the feed roller 4 to the reverse roller 5 is output from the torque limiter 6. The torque applied to the reverse roller 5 in the opposite direction to the paper feed direction is overcome, the reverse roller 5 is rotated in the paper feed direction, and the paper 1 is fed as it is.

Here, in this paper feeding apparatus, a conditional expression of a normal paper feeding range in which double feeding and non-feeding do not occur is as follows. _{T A / μr + (μp /} μr) · m <P B <T A / μp-
3 m However, T _A : Torque applied from the torque limiter to the reverse roller (paper returning force) P _B : Pressing force of the reverse roller against the feed roller (reverse roller pressing force) μp: Coefficient of friction between papers μr: With feed roller Coefficient of friction with sheet m: weight of one sheet Further, a normal sheet feeding range based on this conditional expression is shown in FIG.

Such a friction separating roller type sheet feeding device has a wider range of types of sheets and a weight of sheets that can be fed and a higher separation accuracy than a sheet feeding device of a corner claw type or a friction separating pad type. .

However, in the case of highly smooth paper such as coated paper, air is released between the papers during long-term storage, and an adhesive force due to negative pressure is generated. It is necessary to separate the sheets and introduce air between the sheets to reduce the adhesion between the sheets. In addition, the OHP paper, the second original drawing paper, and the like are likely to have an adhesive force due to static electricity when the humidity is low.

As described above, the normal feeding range when the adhesive force Q acts between the sheets is as shown in the following equation and FIG. T _A / μr + (μp / μr) ・ m + Q / μr <P _B <T _A / μ
p-3m-2Q / μp As is clear from FIG. 6, when the adhesive force Q acts between the sheets, the multi-feed line shifts downward by 2Q / μp, as compared with the case where the adhesive force Q does not act. The feed line is Q / μ
The paper feed range is shifted upward by r, and the normal paper feed range is shifted in the upper right direction as a whole. Therefore, the set point (point X in FIGS. 5 and 6) of the original sheet returning force T _A and the reverse roller pressure contact force P _B is outside the normal sheet feeding range,
Normal paper feeding cannot be performed as it is. Therefore, it is necessary to separate the sheets in order to eliminate the adhesion Q between the sheets.

Here, if the paper return force T _A and the reverse roller pressure contact force P _B can be increased in accordance with the adhesion force Q between the paper sheets, the paper can be fed without the trouble of sorting. From such a viewpoint, a sheet feeding device has been proposed in which the sheet returning force T _A and the reverse roller pressure contact force P _B can be changed in several steps.

[0011]

However, the paper return force T
_{When A} and the reverse roller pressure contact force P _B can be changed independently, the degree of freedom of setting increases, but the setting operation for setting the appropriate conditions is complicated, and the setting is not appropriate It may be defective.

Therefore, according to the present invention, the reverse roller pressure contact force P is used.
_An object of the present invention is to provide a sheet feeding device that can change _B and the sheet returning force T _A at the same time by one operation, and that can smoothly feed the sheet even when a contact force is generated between the sheets. To do.

[0013]

[0014]

Means for Solving the Problems The invention according to claim 1,
The feed roller includes a feed roller that is driven to rotate in the paper feed direction, and a reverse roller that is pressed against the outer peripheral surface of the feed roller to apply a predetermined torque in the opposite direction to the paper feed direction. In a paper feed device of a friction separation roller system that separates and feeds a sheet that has been double-fed between and A driven friction roller is provided coaxially, and a drive friction roller that applies a predetermined friction torque to the driven friction roller is arranged on the opposite side of the feed roller sandwiching the rotation axis of the reverse roller. By increasing or decreasing the pressure contact force of the roller with respect to the driven friction roller ,
The pressure contact force of the reverse roller against the feed roller
And increase or decrease the paper return force by the reverse roller
I did it. Therefore, by increasing the pressure contact force of the driving friction roller with the driven friction roller, the reverse roller is pressed against the feed roller, and the pressure contact force of the reverse roller with respect to the feed roller increases. Further, by increasing the pressure contact force of the driving friction roller with the driven friction roller, the torque acting on the driven friction roller and the reverse roller rotating integrally with the driven friction roller increases, and the sheet returning force by the reverse roller also increases.
Therefore, the pressure contact force of the reverse roller and the sheet return force are increased / decreased in a positive correlation, and the pressure contact force of the reverse roller and the sheet return force are increased / decreased simultaneously according to the magnitude of the adhesion force acting between the sheets. Therefore, it is possible to set the pressure contact force of the reverse roller and the paper return force to a value at which normal paper feeding can be performed by performing only one switching operation.

According to a second aspect of the present invention, in the first aspect of the invention, the coefficient of friction between the sheets is μp, the coefficient of friction between the feed roller and the sheet is μr, the radius of the reverse roller is Rr, and the driven friction roller. Where R is the radius of the friction coefficient μ between the driven friction roller and the driving friction roller.
Was set as μ≈ (Rr / R) · (μp + 2μr) / 3.
This makes it possible to minimize the amount of increase in the pressure contact force of the reverse roller and the paper return force of the reverse roller for performing normal paper feed when a contact force is generated between the paper. And the power transmission system is not overloaded.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The same parts as those described in FIG. 4 are designated by the same reference numerals. A pickup roller 3 is provided above the cassette 2 in which the sheets 1 are stored to sequentially feed the sheets 1 stored in the cassette 2 from the topmost sheet in the sheet feeding direction. On the downstream side of the sheet 1 fed by the pickup roller 3 in the sheet feeding direction, a feed roller 7 that is rotationally driven in the sheet feeding direction, and a reverse roller 8 that is pressed against the outer peripheral surface of the feed roller 7 so as to be able to come into contact with and separate from the outer surface. Are arranged.

The rotating shaft 8a of the reverse roller 8 is a pair of arms 10 which are vertically rotatable about a supporting shaft 9 as a fulcrum.
And the reverse roller 8 comes in contact with and separates from the feed roller 7 by rotating the arm 10 in the up-down direction with the support shaft 9 as a fulcrum. A driven friction roller 11 is fixed to the rotary shaft 8a.
1 and the reverse roller 8 rotate integrally.

A drive friction roller 12 is arranged at a position opposite to the feed roller 7 across the rotary shaft 8a so as to be brought into contact with and separated from the outer peripheral surface of the driven friction roller 11. The rotary shaft 12a of the drive friction roller 12 is held by a pair of arms 14 which are vertically rotatable about a support shaft 13 as a fulcrum, and the arm 14 is vertically rotated about the support shaft 13 as a fulcrum to drive friction. Roller 12
Moves toward and away from the driven friction roller 11. Gears 15a, 15b, and 15c for transmitting a driving force to the driving friction roller 12 are attached to the one arm 14, and the gear 15c is fixed to the rotating shaft 12a. Also,
One end of the arm 14 on the side of the support shaft 13 has a protrusion 1
6 is fixed, and the spring 1 is attached to the tip of the protrusion 16.
One end of the spring 7 is locked, and the biasing force of the spring 17 acts in a direction in which the friction drive roller 12 is brought into pressure contact with the driven friction roller 11. The other end of the spring 17 is locked by an operation lever (not shown) that adjusts the contact pressure of the friction drive roller 12 to the driven friction roller 11 by adjusting the extension of the spring 17.

The rotary shafts 8a and 12a and the rotary shaft 7a of the feed roller 7 are arranged in a direction substantially orthogonal to the extending direction of the arms 10 and 14, and the friction drive roller 12 is driven by the driven friction. Predetermined pressure contact force P to the roller 11
When the pressure is applied by _B , the pressure contact force of the reverse roller 8 with respect to the feed roller 7 (reverse roller pressure contact force) is also P _B.

Here, the radius of the driven friction roller 11 is R, and the radius of the reverse roller 8 is Rr.
Set μ and R so that = T _A · Rr (however,
T is a frictional force between the driving friction roller 12 and the driven friction roller 11, and T = μ · P _B. μ is a friction coefficient between the driving friction roller 12 and the driven friction roller 11), so that the slip between the driving friction roller 12 and the driven friction roller 11 acts as a torque limiter, which is different from the conventional example shown in FIG. Similarly, it is possible to perform paper feeding while preventing double feeding.

FIG. 3 shows a normal sheet feeding range when there is no close contact between the sheets and when there is close contact between the sheets. The inclination of the straight line connecting the intersection points A and B of the double feed line and the non-feed line is 3 / (μp + 2μr). On the other hand, the reverse roller pressure contact force P _B and the paper return force T _A
The relationship between a _{P B = (Rr / R)} · (1 / μ) · T A, the slope (Rr / R) · (1 / μ), the intersection point A,
By making the inclination of the straight line connecting B substantially equal to 3 / (μp + 2μr), what relationship should be exerted between the reverse roller pressure contact force P _B and the sheet return force T _A when an adhesive force is generated between the sheets. It becomes clear whether to shift. (Rr / R) ・ (1 / μ) and 3 / (μp + 2μ
If r) is approximately the same, μ ≈ (Rr / R)
It becomes (μp + 2μr) / 3.

In such a configuration, the gears 15a-1
The driving friction roller 1 is driven by the driving force transmitted via 5c.
When 2 is rotationally driven, a frictional force T (T = μ · P _B ) is generated between the driving friction roller 12 and the driven friction roller 11.

The pressure contact force of the drive friction roller 12 with respect to the driven friction roller 11, that is, the reverse roller pressure contact force P _B is
The reverse roller pressure contact force P _B can be changed by operating the operating lever to expand and contract the spring 17, which is applied by the tensile force of the spring 17.
Specifically, when the operation lever is operated to extend the spring 17, the pressure contact force of the drive friction roller 12 to the driven friction roller 11 increases, and the driven friction roller 11 and the reverse roller 8 move upward with the support shaft 9 as a fulcrum. When the reverse roller 8 is rotated to and the reverse roller 8 is pressed against the feed roller 7, the reverse roller pressure contact force P _B is also increased.

If the pressure contact force P _B of the driving friction roller 12 to the driven friction roller 11 is increased, the friction force T (T = μ · P _B ) acting between the driving friction roller 12 and the driven friction roller 11 is increased. Becomes larger, the driven friction roller 11
Friction torque applied to, i.e., the greater the torque applied to the reverse roller 8, the paper by reverse roller 8 return force _{T A (T A = T ·} R / Rr) is also increased.

Therefore, when the adhesive force between the sheets increases and normal feeding cannot be performed, the pressure contact force between the driving friction roller 12 and the driven friction roller 11 is increased to increase the reverse roller pressure contact force P _B. By performing the increasing operation, the paper return force T _A can be increased at the same time. That is, the reverse roller pressure contact force P _B and the sheet return force T _A can be increased or decreased in a positive correlation as shown in FIG.

Further, as shown in FIG. 3, the inclination of the straight line connecting the intersection points A and B and the inclination of the relationship between the reverse roller pressure contact force P _B and the sheet returning force T _A are made substantially equal to each other, and μ≈ (Rr /
R) · (μp + 2μr) / 3, it is necessary to increase the reverse roller pressure contact force P _B and the paper return force T _{A in} order to feed the paper normally when the adhesive force is generated between the paper. It can be minimized and it is possible to prevent an excessive load from being applied to the drive system and the power transmission system.

[0027]

[0028]

Effects of the Invention According to the first aspect of the present invention, when the adhesive force acting between the sheet to be fed is changed, by increasing or decreasing the press contact force of the driving friction roller against the driven friction roller accordingly , It is possible to increase / decrease the pressure contact force of the reverse roller with respect to the feed roller and the paper return force of the reverse roller with a positive correlation.
Therefore, it is possible to easily set the pressure contact force of the reverse roller and the paper return force necessary for proper feeding when the magnitude of the adhesion force acting between the papers changes. Therefore, even if the adhesive force between the sheets changes, the sheet can be smoothly fed without performing the work of separating the sheets.

According to the second aspect of the present invention, when the adhesive force acting between the sheets to be fed increases, the amount of increase in the pressure contact force of the reverse roller and the sheet by the reverse roller for normal feeding The amount of increase in the returning force can be suppressed to a necessary minimum, and the feeding can be continued without applying an excessive load to the drive system and the power transmission system.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a front view thereof.

FIG. 3 is a graph showing a normal paper feeding range when there is no close contact between the sheets and when there is close contact between the sheets.

FIG. 4 is a side view showing a conventional example.

FIG. 5 is a graph showing a normal sheet feeding range in the case where there is no adhesive force between sheets.

FIG. 6 is a graph showing a normal sheet feeding range when there is a close contact force between sheets.

[Explanation of symbols]

1 sheet 7 Feed roller 8 Reverse roller 8a rotating shaft 11 Driven friction roller 12 Drive friction roller

Claims (2)

(57) [Claims] 1. A feed roller rotatably driven in a sheet feeding direction, and a reverse roller that is pressed against an outer peripheral surface of the feed roller and applies a predetermined torque in a direction opposite to the sheet feeding direction. In a paper feed device of a friction separation roller system for separating and feeding the paper that has been double-fed between a feed roller and a reverse roller, the reverse roller is provided so as to come in contact with and separate from the feed roller. A driven friction roller that rotates integrally with the driven friction roller is coaxially provided, and a drive friction roller that applies a predetermined friction torque to the driven friction roller is arranged on the opposite side of the feed roller sandwiching the rotation axis of the reverse roller. Increase or decrease the pressure contact force of the driving friction roller with the driven friction roller.
By doing so, the river with respect to the feed roller is
Pressing force of the roller and paper return by the reverse roller
A paper feeding device characterized by increasing and decreasing force . 2. When the friction coefficient between the sheets is μp, the friction coefficient between the feed roller and the sheet is μr, the radius of the reverse roller is Rr, and the radius of the driven friction roller is R, the following friction roller is used. Friction coefficient with driving friction roller μ
The, μ ≒ (Rr / R) · (μp + 2μr) / 3 and the possible sheet feeding apparatus according to claim 1, wherein.