JPH07315605A - Paper feeder - Google Patents

Abstract

PURPOSE:To completely prevent double feeding (to send two sheets one upon another), by providing a power spring by accumulating the torque, which rotates the reverse roller in the direction opposite to the paper feeding direction, when the reverse roller shaft is turned by a feed roller together with a reverse roller in the paper feeding direction. CONSTITUTION:As a reverse roller shaft 7 corotates in the paper feeding direction (direction (b) as shown by an arrow mark), a power spring 12, a central end of which is fixed to the reverse roller 4, is gradually tightened through winding, so that the torque, by which a reverse roller 4 is turned in the direction opposite to the paper feeding direction, is accumulated. When two or more paper sheets 1 are sent into a nip part between the feed roller 3 and the reverse roller 4, a slip occurs between two paper sheets 1, thereby reducing the torque transmitted from the feed roller 3 to the reverse roller 4. As a result, the torque accumulated in the power spring 12 becomes larger than the torque by which the reverse roller 4 is turned in the paper feeding direction, thereby preventing double feeding of the paper sheet 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a feed roller and a reverse roller whose outer peripheral surfaces are in contact with each other. When the paper is fed one by one, the reverse roller is rotated along with the feed roller. By doing so, smooth paper feeding is performed, and when two or more sheets enter the nip portion between the feed roller and the reverse roller, the reverse roller is rotationally driven in the direction opposite to the paper feeding direction to prevent double feeding. The present invention relates to an FRR (Feed & Reverse Roller) type sheet feeding device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, an FR having the above-described feed roller and reverse roller in order to reliably feed the sheets one by one.
Some R-type sheet feeders are used, and the structure and operation of the FRR-type sheet feeder will be described with reference to FIGS.

First, a paper feed cassette 2 accommodating a paper 1 is detachably provided to an image forming apparatus main body (not shown), and a position facing the leading end side of the paper feed cassette 2 in the paper feed direction. Further, a feed roller 3 and a reverse roller 4 whose outer peripheral surfaces are in contact with each other are provided. Further, there is provided a pickup roller 5 that feeds the sheets 1 accommodated in the sheet feeding cassette 2 toward the nip portion between the feed roller 3 and the reverse roller 4 in order from the uppermost sheet.

Here, a drive motor (not shown) is connected to the feed roller 3 to feed the paper in the paper feeding direction (arrow a).
Direction). Also, the reverse roller 4
Is supported by a reverse roller shaft 7 via a torque limiter 6, and the reverse roller 4 is pressed against the outer peripheral surface of the feed roller 3 by a pressure spring 8.

Next, a drive shaft 9 having an axis parallel to the reverse roller shaft 7 is provided.
The drive gear 10 fixed to the rear roller shaft 7 and the driven gear 11 fixed to the reverse roller shaft 7 mesh with each other. The rotational force from a drive motor (not shown) connected to the drive shaft 9 acts in a direction to rotate the reverse roller 4 in the direction opposite to the paper feeding direction.

In such a structure, the feed roller 3 is rotationally driven in the paper feeding direction (the direction of arrow a) during paper feeding, and the rotational force transmitted from the drive shaft 9 to the reverse roller 4 is the reverse roller. Shaft 7 and torque limiter 6
The reverse roller 4 acts in a direction (arrow b'direction) opposite to the paper feeding direction via the. But,
The reverse roller 4 circumscribing the feed roller 3 is
The torque transmitted from the feed roller 3 causes the torque limiter 6 to idle and is rotated in the paper feeding direction (arrow b direction). Even after one sheet of paper 1 is fed into the nip portion between the feed roller 3 and the reverse roller 4 by the action of the pickup roller 5, the rotational force from the feed roller 3 is applied to the paper 1 as shown in FIG. To the reverse roller 4, and the reverse roller 4 is rotated in the paper feeding direction. Therefore, the feed roller 3 and the reverse roller 4 both rotate in the paper feeding direction, so that smooth paper feeding is performed.

On the other hand, as shown in FIG.
When two or more sheets 1 are fed into the nip between the reverse roller 4 and the reverse roller 4, the slip between the two sheets 1 occurs, and the rotational force transmitted from the feed roller 3 to the reverse roller 4 is generated. Than drive shaft 9 to reverse roller 4
The rotational force transmitted to the reverse roller 4 is increased, and the reverse roller 4 is rotationally driven in the direction opposite to the paper feeding direction (arrow b'direction).
As a result, the sheet 1 on the side that comes into contact with the reverse roller 4 is returned to the inside of the sheet feeding cassette 2, and the double feeding of the sheet 1 is prevented.

[0008]

However, in the above-described sheet feeding device, a reverse mechanism for transmitting a rotational force in the direction opposite to the sheet feeding direction to the reverse roller 4, specifically,
A drive shaft 9, a drive gear 10, a driven gear 11, a drive motor connected to the drive shaft 9, and the like are required, and a space for arranging the reverse mechanism must be secured, resulting in an increase in size of the image forming apparatus. In addition, the cost will increase due to an increase in the number of parts.

Therefore, in order to save the space for installing the reverse mechanism and reduce the cost by reducing the number of parts, the force when the reverse roller 4 is rotated in the paper feeding direction is reversed by a coil spring or a torsion spring. The reverse roller is stored as a rotational force for rotating the roller in the direction opposite to the paper feeding direction, and when the two or more sheets 1 are fed into the nip portion between the feed roller 3 and the reverse roller 4, the reverse roller is generated by the force stored in the coil spring or the like. There is also proposed a sheet feeding device in which 4 is rotated in the direction opposite to the sheet feeding direction.

However, due to the rotational force stored in the coil spring or the torsion spring, the reverse roller 4 can be rotated only 1/2 to 1 rotation in the direction opposite to the paper feeding direction, and therefore 3 to 10 sheets of paper can be rotated. When 1 is fed into the nip portion between the feed roller 3 and the reverse roller 4, the double feeding of the sheets 1 cannot be completely prevented.

[0011]

The invention according to claim 1 is
In a paper feeding device having a feed roller rotatably driven in a paper feeding direction and a reverse roller rotatably supported by a reverse roller shaft via a torque limiter and circumscribing the feed roller, a central end is the reverse roller shaft. A spring spring that is fixed to the spring and that stores a rotational force for rotating the reverse roller in the direction opposite to the paper feed direction by being wound around when the reverse roller shaft is rotated together with the reverse roller in the paper feed direction by the reverse roller. Provided.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the reverse roller shaft, the torque limiter, and the reverse roller are attached to a sheet cassette that is detachable from the image forming apparatus main body. A rotation restricting member that restricts the rotation of the reverse roller shaft when the reverse roller is separated from the feed roller when the paper cassette is removed from the main body is provided.

[0013]

According to the present invention, when the reverse roller shaft is rotated together with the reverse roller in the paper feeding direction by the feed roller rotating in the paper feeding direction, the main spring whose center end is fixed to the reverse roller shaft is wound. It is tightened and the rotational force for rotating the reverse roller in the direction opposite to the paper feeding direction is stored. When two or more sheets of paper get into the nip between the feed roller and reverse roller,
The stored rotational force drives the reverse roller to rotate in the direction opposite to the paper feeding direction, thereby preventing double feeding of paper. Note that the mainspring can store a rotational force for rotating the reverse roller a number of times in the direction opposite to the paper feeding direction, and the rotational force applied to the nip portion between the feed roller and the reverse roller is 3
Even when more than one sheet of paper has entered, the reverse roller is rotated many times in the direction opposite to the paper feeding direction by the rotational force of the spring, and the double feeding of the paper 1 is completely prevented.

According to the second aspect of the invention, when the reverse roller is separated from the feed roller by removing the paper feed cassette from the main body of the image forming apparatus, the rotation restricting member restricts the rotation of the reverse roller shaft. The rotational force for rotating the reverse roller in the direction opposite to the paper feeding direction is retained without being released. Therefore, even if two or more sheets enter the nip portion between the feed roller and the reverse roller immediately after the sheet cassette is set in the main body of the image forming apparatus and the paper feeding is started, the reverse roller does not have the spring spring. Due to the rotational force stored in the sheet, the sheet is rotated in the direction opposite to the sheet feeding direction, and the double feeding of sheets is prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described with reference to FIGS. The same parts as those described in FIGS. 5 to 8 are designated by the same reference numerals, and the description thereof will be omitted (the same applies hereinafter). A feed roller 3 and a reverse roller 4 whose outer peripheral surfaces are in contact with each other are provided, and the reverse roller 4 is pivotally supported by a reverse roller shaft 7 via a torque limiter 6. A drive motor for driving the feed roller 3 to rotate in the paper feeding direction (direction of arrow a) is connected to the feed roller 3.

Next, the center end is connected to the reverse roller shaft 7
A mainspring spring 12 fixed to the reverse spring shaft 12 is provided so as to be wound and tightened when the reverse roller shaft 7 is rotated together with the reverse roller 4 by the feed roller 3.

In such a structure, the feed roller 3 is in contact with the reverse roller 4 or the sheet 1 is fed to the nip portion between the feed roller 3 and the reverse roller 4 in the sheet feeding direction. When it is rotationally driven to, the rotational force transmitted from the feed roller 3 rotates in the paper feeding direction (arrow b direction). Immediately after the reverse roller 4 starts to rotate in the sheet feeding direction, the torque limiter 6 and the reverse roller shaft 7 are rotated together with the reverse roller 4 in the sheet feeding direction.

Here, the reverse roller shaft 7 is rotated in the paper feeding direction (the direction of arrow b) so that the center end of the mainspring spring 12 is fixed to the reverse roller shaft 7.
Is gradually tightened, and a rotational force for rotating the reverse roller 4 in the direction opposite to the sheet feeding direction (direction of arrow b ′) is stored in the main spring 12. When the mainspring 12 is wound up to a predetermined state, the torque limiter 6 and the reverse roller shaft 7 cannot be rotated in the paper feeding direction due to the rotational force of the reverse roller 4 which rotates in the paper feeding direction. The roller 4 slides with respect to the torque limiter 6, and only the reverse roller 4 is rotated in the paper feeding direction.

Next, when two or more sheets of paper 1 are fed into the nip portion between the feed roller 3 and the reverse roller 4, slippage occurs between the two sheets of paper 1, and the feed roller 3 and the reverse roller 4 move. The rotational force transmitted to is reduced. The rotational force stored in the main spring 12 becomes larger than the rotational force that rotates the reverse roller 4 in the sheet feeding direction. The rotational force stored in the main spring 12 causes the reverse roller 4 and the torque limiter to rotate. 6 and 6 are rotated in the direction opposite to the paper feeding direction (direction of arrow b ′). As a result, the sheet 1 on the side in contact with the reverse roller 4 is returned to the inside of the sheet feeding cassette 2, and the double feeding of the sheet 1 is prevented.

Here, as the reverse mechanism for rotating the reverse roller 4 in the direction opposite to the paper feeding direction, it is sufficient to provide only the mainspring 12, and the structure is extremely simple, the number of parts is reduced, and the cost is reduced. To be done.
Further, since a large installation space is not required, it is possible to reduce the size and weight of the image forming apparatus.

Moreover, the mainspring 12 can store a rotational force for rotating the reverse roller 4 a number of times. Therefore, a large number of sheets 1 of 3 to 10 are fed to the nip portion between the feed roller 3 and the reverse roller 4. When it enters, the reverse roller 4 rotates in the direction opposite to the sheet feeding direction many times until all the second or more sheets 1 are returned to the sheet feeding cassette 2, and the double feeding of the sheets 1 is completely prevented. It

Next, an embodiment of the invention described in claim 2 will be described with reference to FIGS. 3 and 4. In this embodiment, the reverse roller shaft 7, the torque limiter 6, and the reverse roller 4 are detachable from the image forming apparatus main body, and the paper feed cassette 2 is detachable.
The reverse spring shaft 7 has a center end of a mainspring 12 fixed thereto. The reverse roller shaft 7 is held by a pressing arm 13, and the reverse roller 4 is brought into contact with and separated from the feed roller 3 by moving the pressing arm 13 up and down.

Next, the support shaft 1 is attached to the paper feed cassette 2.
A rotation restricting member 15 is provided that is rotatably supported around 4, and has three arm portions 15a to 15c. An engaging portion 17 that engages with a spring pin 16 press-fitted into the reverse roller shaft 7 in a disengageable manner is provided at a tip portion of the arm portion 15a, and a tip portion of the arm portion 15b is connected via a link mechanism 18. The arm portion 15c is connected to the pressure arm 13 and contacts the fixed shaft 19 provided in the image forming apparatus main body when the paper feed cassette 2 is set in the image forming apparatus main body, and the rotation regulating member 15 is supported by the support shaft 14. It functions to rotate in the direction of arrow c. The rotation restricting member 15 is provided with the rotation restricting member 15 as the support shaft 14.
A spring (not shown) is provided for urging in a direction to rotate in the direction of arrow c '.

In such a structure, FIG. 3 shows a state in which the paper feed cassette 2 is set in the main body of the image forming apparatus. When the arm portion 15c abuts on the fixed shaft 19, the rotation regulating member 15 is indicated by the arrow c. The spring pin 1 and the engaging portion 17 provided at the tip of the arm portion 15a.
The engagement state with 6 is released, and the tip end side of the arm portion 15b rises to push up the pressure arm 13 connected via the link mechanism 18, and the reverse roller 4 is brought to the outer peripheral surface of the feed roller 3. It is pressed.

Then, the sheet feeding operation is started after the sheet feeding cassette 2 is set in the main body of the image forming apparatus as described above, so that the sheet feeding direction is changed in the same manner as the embodiment described with reference to FIGS. The reverse roller 4 is rotated by the feed roller 3 which is rotationally driven, and the spring 1
2 is wound up and the rotational force for rotating the reverse roller 4 in the direction opposite to the paper feeding direction is stored.

Then, when two or more sheets 1 are fed into the nip portion between the feed roller 3 and the reverse roller 4, the reverse roller 4 rotates in the direction opposite to the paper feeding direction by the rotational force stored in the main spring 12. It is driven and double feeding of the sheet 1 is prevented.

Next, FIG. 4 shows a state in which the paper feed cassette 2 is detached from the main body of the image forming apparatus. When the arm portion 15c moves away from the fixed shaft 19, the rotation restricting member 15 rotates around the support shaft 14. In the direction of arrow c ', the engaging portion 17 provided at the tip of the arm portion 15a engages with the spring pin 16 to regulate the rotation of the reverse roller shaft 7. The rotation restricting member 15 rotates in the direction of arrow c'to write on the tip side of the arm portion 15b, and the pressure roller 13 connected via the link mechanism 18 is pulled down to cause the reverse roller 4 to feed. It has descended to a position away from 3. Therefore, when the paper feed cassette 2 is removed from the main body of the image forming apparatus, the reverse roller 4 is separated from the feed roller 3, so that the reverse roller 4 and the feed roller 3 do not rub against each other and can be taken out smoothly. It

Here, when the pressure acting on the reverse roller 4 from the feed roller 3 disappears when the reverse roller 4 separates from the feed roller 3, the reverse roller shaft 7 and the reverse roller 7 are driven by the rotational force stored in the spring 12. The roller 4 or the like tries to rotate in the direction opposite to the paper feeding direction. However, substantially at the same time that the reverse roller 4 separates from the feed roller 3, the engaging portion 17 engages with the spring pin 16 to regulate the rotation of the reverse roller shaft 7 and the reverse roller 4 in the direction opposite to the paper feeding direction. . Therefore, even when the reverse roller 4 is separated from the feed roller 3 as the paper feed cassette 2 is taken out from the image forming apparatus main body, the reverse roller 4 stored in the mainspring 12 is rotated in the direction opposite to the paper feed direction. The rotational force is retained without being released.

Therefore, immediately after the paper feed cassette 2 is set in the main body of the image forming apparatus and the paper feed is started, two or more papers 1 enter the nip portion between the feed roller 3 and the reverse roller 4. However, the reverse roller 4 is rotated in the direction opposite to the paper feeding direction by the rotational force stored in the main spring 12, and the double feeding of the paper 1 is prevented.

[0030]

As described above, according to the first aspect of the invention, the feed roller which is rotationally driven in the sheet feeding direction and the reverse roller shaft are rotatably supported by the torque limiter and circumscribed on the feed roller. In a paper feeding device having a reverse roller, the center end is fixed to the reverse roller shaft, and the reverse roller shaft is wound and tightened when the reverse roller is rotated together with the reverse roller in the paper feeding direction by the feed roller. Since a spring spring that stores a rotational force that rotates the roller in the direction opposite to the paper feeding direction is provided, when two or more sheets enter the nip portion between the feed roller and the reverse roller, the reverse roller is in the opposite direction to the paper feeding direction. A simple structure in which the spring is attached to the reverse roller shaft to prevent double feeding of paper by rotating Therefore, when the reverse roller is rotated by the rotational force stored in the main spring, the reverse roller can be continuously rotated many times. Therefore, the nip portion between the feed roller and the reverse roller can be realized. Even when three or more sheets of paper are inserted into the paper, all the paper except the paper that is in contact with the feed roller can be returned in the direction opposite to the paper feeding direction by continuously rotating the mainspring spring many times. This has the effect of completely preventing double feeding of paper.

According to a second aspect of the present invention, as described above, in the first aspect of the invention, the reverse roller shaft, the torque limiter, and the reverse roller are attached to a paper feed cassette that is detachable from the image forming apparatus main body. Since the rotation regulating member that regulates the rotation of the reverse roller shaft when the reverse roller is separated from the feed roller due to the removal of the paper feeding cassette from the image forming apparatus main body is provided, the paper feeding cassette is used as the image forming apparatus. When removed from the main body, the rotation of the reverse roller shaft can be restricted by the rotation restricting member, which allows the rotational force stored in the main spring to be retained without being released. Immediately after setting the main body of the image forming apparatus and starting feeding, two or more sheets of paper are fed by the feed roller and the reverse roller. Even when it enters the nip portion, the reverse roller can be rotated in the direction opposite to the paper feeding direction by the rotational force stored in the mainspring, and therefore, immediately after the paper feeding cassette is set in the image forming apparatus main body. Also in this case, it is possible to prevent double feeding of paper.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the invention described in claim 1.

FIG. 2 is a perspective view thereof.

FIG. 3 is a front view showing a state in which a paper feed cassette according to an embodiment of the present invention is set in the image forming apparatus main body.

FIG. 4 is a front view showing a state in which a paper feed cassette is taken out from the main body of the image forming apparatus.

FIG. 5 is a side view showing a conventional example.

FIG. 6 is a front view thereof.

FIG. 7 is a side view illustrating a rotation state of a feed roller and a reverse roller when feeding one sheet of paper.

FIG. 8 is a side view illustrating a rotation state of the feed roller and the reverse roller when two sheets of paper have entered the nip portion between the feed roller and the reverse roller.

[Explanation of symbols]

 2 Paper feed cassette 3 Feed roller 4 Reverse roller 6 Torque limiter 7 Reverse roller shaft 12 Spring spring 15 Rotation restriction member

Claims (2)

[Claims] 1. A sheet feeding device having a feed roller rotatably driven in a sheet feeding direction and a reverse roller rotatably supported by a reverse roller shaft through a torque limiter and circumscribing the feed roller. Is fixed to the reverse roller shaft and is rotated when the reverse roller shaft is rotated together with the reverse roller in the paper feeding direction by the feed roller to rotate the reverse roller in a direction opposite to the paper feeding direction. A paper feeding device characterized by having a power spring for storing power. 2. A reverse roller shaft, a torque limiter, and a reverse roller are attached to a paper feed cassette that is detachable from the main body of the image forming apparatus, and the reverse roller is attached when the paper feed cassette is removed from the main body of the image forming apparatus. The sheet feeding device according to claim 1, further comprising a rotation regulating member that regulates rotation of the reverse roller shaft when the sheet is separated from the feed roller.