JP3365685B2 - Paper feeder - Google Patents

Description

Description: 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 circumscribed to each other, and when paper is fed one by one. When the two or more papers enter the nip between the feed roller and the reverse roller, the reverse roller is turned in the opposite direction to the paper feed direction. The present invention relates to an FRR (Feed & Reverse Roller) type sheet feeding device in which a double feed is prevented by being rotationally driven. 2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, an FR having a feed roller and a reverse roller as described above in order to reliably feed sheets one by one.
There is an apparatus using an R-type paper feeder. The structure and operation of the FRR-type paper feeder will be described with reference to FIGS. First, a paper feed cassette 2 containing paper 1 is provided detachably with respect to an image forming apparatus main body (not shown), and is located at a position facing the front end of the paper feed cassette 2 in the paper feeding direction. In addition, a feed roller 3 and a reverse roller 4 whose outer peripheral surfaces are circumscribed to each other are provided. Further, there is provided a pickup roller 5 for feeding the paper 1 stored in the paper feed cassette 2 toward the nip portion between the feed roller 3 and the reverse roller 4 in order from the top one. Here, a drive motor (not shown) is connected to the feed roller 3 so that the feed roller 3 can feed in the sheet feeding direction (arrow a).
Direction). 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.
And a driven gear 11 fixed to the reverse roller shaft 7 meshes. The rotation force from a drive motor (not shown) connected to the drive shaft 9 acts in a direction to rotate the reverse roller 4 in a direction opposite to the sheet feeding direction. In such a configuration, at the time of paper feeding, the feed roller 3 is driven to rotate in the paper feeding direction (the direction of arrow a), and the rotational force transmitted from the drive shaft 9 to the reverse roller 4 is transmitted to the reverse roller 4. Shaft 7 and torque limiter 6
And acts in a direction to rotate the reverse roller 4 in the direction opposite to the sheet feeding direction (the direction of the arrow b '). But,
The reverse roller 4 circumscribing the feed roller 3 is
Due to the rotational force transmitted from the feed roller 3, the torque limiter 6 is idled, and is rotated in the sheet feeding direction (the direction of the arrow b). Even after one sheet of paper 1 is fed into the nip between the feed roller 3 and the reverse roller 4 by the action of the pickup roller 5, as shown in FIG. To the reverse roller 4, and the reverse roller 4 is rotated in the sheet feeding direction. Therefore, when the feed roller 3 and the reverse roller 4 are both rotated in the paper feeding direction, smooth paper feeding is performed. On the other hand, as shown in FIG.
When two or more sheets 1 are fed to the nip portion between the sheet 1 and the reverse roller 4, slippage occurs between the two sheets 1, and the rotational force transmitted from the feed roller 3 to the reverse roller 4 From the drive shaft 9 to the reverse roller 4
The reverse roller 4 is driven to rotate in the direction opposite to the sheet feeding direction (the direction of the arrow b ').
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 cassette 2, and double feeding of the sheet 1 is prevented. However, in the above-described paper feeder, a reverse mechanism for transmitting a rotational force to the reverse roller 4 in a direction opposite to the paper feed direction, 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 ensured. In addition, the cost increases due to an increase in the number of parts and the like. Therefore, in order to save space by installing a reverse mechanism and to reduce costs 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 roller is stored as a rotational force for rotating the roller in the direction opposite to the paper feeding direction, and the reverse roller is driven by the force stored in the coil spring or the like when two or more sheets of paper 1 are fed into the nip between the feed roller 3 and the reverse roller 4 There is also proposed a sheet feeding device in which the sheet 4 is rotated in a direction opposite to the sheet feeding direction. However, depending on the rotational force stored in the coil spring or the torsion spring, the reverse roller 4 can be rotated only 1/2 to 1 turn in the direction opposite to the sheet feeding direction. When the sheet 1 is fed into the nip portion between the feed roller 3 and the reverse roller 4, double feeding of the sheet 1 cannot be completely prevented. According to the present invention, there is provided a feed roller rotatably driven in a sheet feeding direction, and a reverse roller which is rotatably supported by a reverse roller shaft via a torque limiter and which is circumscribed by the feed roller. A roller having a center end fixed to the reverse roller shaft, and the reverse roller shaft being wound and fastened when the reverse roller shaft is rotated together with the reverse roller in the paper feeding direction by the feed roller. There is provided a mainspring that stores a rotational force for rotating the paper in the direction opposite to the paper feeding direction. In this case , a reverse roller shaft, a torque limiter, and a reverse roller are mounted on a paper cassette that is detachable from the main body of the image forming apparatus, and the paper feed cassette is detached from the main body of the image forming apparatus. A rotation regulating member that regulates rotation of the reverse roller shaft when the reverse roller separates from the feed roller may be provided. 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 fixed at the center end to the reverse roller shaft is tightened. Then, a rotational force for rotating the reverse roller in the direction opposite to the sheet feeding direction is stored. When two or more sheets enter the nip between the feed roller and the reverse roller, the stored rotational force drives the reverse roller to rotate in the direction opposite to the sheet feeding direction, thereby preventing double feeding of sheets. . Note that the mainspring can store a rotational force for rotating the reverse roller many times in the direction opposite to the paper feeding direction. Even when three or more sheets enter the nip between the feed roller and the reverse roller, By rotating the reverse roller many times in the direction opposite to the paper feeding direction by the rotation force of the mainspring,
Double feed is completely prevented. In the case where the rotation restricting member is provided, when the reverse roller is separated from the feed roller by removing the sheet cassette from the image forming apparatus main body, the rotation restricting member is rotated by the reverse roller shaft. In order to regulate the rotation of the spring, the rotational force for rotating the reverse roller stored in the mainspring in the direction opposite to the sheet feeding direction is maintained without being released. For this reason, even if two or more sheets enter the nip portion between the feed roller and the reverse roller immediately after the paper cassette is set in the image forming apparatus main body and the paper feeding is started, the reverse roller is kept in the spring-loaded state. Is rotated in the direction opposite to the paper feed direction by the rotational force stored in the
Double feeding of paper is prevented. An embodiment of the present invention will be described with reference to FIGS. The same parts as those described in FIGS. 5 to 8 are denoted by the same reference numerals, and description thereof will be omitted (the same applies hereinafter). A feed roller 3 and a reverse roller 4 whose outer peripheral surfaces are circumscribed are provided. The reverse roller 4 is supported by a reverse roller shaft 7 via a torque limiter 6. The feed roller 3 is connected to a drive motor for rotating the feed roller 3 in the sheet feeding direction (the direction of arrow a). Next, the center end is connected to the reverse roller shaft 7.
The mainspring 12 is mounted in such a direction as to be wound when the reverse roller shaft 7 is rotated by the feed roller 3 together with the reverse roller 4. In such a configuration, the feeding direction is set in a state where the feed roller 3 is in contact with the reverse roller 4 or in a state where one sheet 1 is fed into the nip portion between the feed roller 3 and the reverse roller 4. When rotated in the sheet feeding direction, the sheet is rotated in the sheet feeding direction (the direction of arrow b) by the rotational force transmitted from the feed roller 3. Immediately after the reverse roller 4 starts to rotate in the paper feeding direction, the torque limiter 6 and the reverse roller shaft 7 are rotated together with the reverse roller 4 in the paper feeding direction. Here, the reverse roller shaft 7 is rotated in the paper feeding direction (the direction of the arrow b) so that the center end of the spring roller 12 is fixed to the reverse roller shaft 7.
Are gradually tightened, and a rotational force for rotating the reverse roller 4 in the direction opposite to the sheet feeding direction (the direction of the arrow b ′) is stored in the mainspring 12. When the mainspring 12 is tightened 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 that rotates in the paper feeding direction. The roller 4 slips with respect to the torque limiter 6, and only the reverse roller 4 is rotated in the sheet 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 reverse rollers 4 Torque transmitted to the motor is reduced. The rotational force stored in the mainspring 12 is greater than the rotational force that causes the reverse roller 4 to rotate in the paper feeding direction. The reverse roller 4 is connected to the reverse roller shaft 7 by the torque stored in the mainspring 12. 6 is driven to rotate in the direction opposite to the sheet feeding direction (the 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 a reverse mechanism for rotating the reverse roller 4 in the direction opposite to the paper feeding direction, it is only necessary to provide the mainspring 12, so that the structure becomes extremely simple, the number of parts is reduced, and cost reduction is achieved. Is done.
Further, since a large installation space is not required, the size and weight of the image forming apparatus can be reduced. Further, the mainspring 12 can store a rotational force for rotating the reverse roller 4 many times, so that three to ten sheets of paper 1 are fed to the nip between the feed roller 3 and the reverse roller 4. When the sheet enters, the reverse roller 4 rotates in the direction opposite to the sheet feeding direction many times until the second sheet or more of the sheet 1 is completely returned to the sheet feeding cassette 2, and the double feeding of the sheet 1 is completely prevented. You. Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the reverse roller shaft 7, the torque limiter 6, and the reverse roller 4 are mounted on the sheet cassette 2 which is detachable from the main body of the image forming apparatus. The center end is fixed. Further, the reverse roller shaft 7 is held by a pressure arm 13,
By moving the pressure arm 13 up and down, the reverse roller 4 comes into contact with and separates from the feed roller 3. Next, the paper feed cassette 2 has a spindle 1
A rotation regulating member 15 rotatably supported around 4 and having three arms 15a to 15c is provided. The distal end of the arm 15a is provided with an engaging portion 17 which is detachably engaged with the spring pin 16 pressed into the reverse roller shaft 7, and the distal end of the arm 15b is connected via a link mechanism 18. The arm 15c is connected to the pressure arm 13, and the arm 15c abuts on a fixed shaft 19 provided in the image forming apparatus main body when the sheet feeding cassette 2 is set in the image forming apparatus main body. In the direction of arrow c. In addition, the rotation restricting member 15 is attached to the support shaft 14.
A spring (not shown) is provided for urging in the direction of rotation in the direction of arrow c '. FIG. 3 shows a state in which the paper feed cassette 2 is set in the main body of the image forming apparatus in such a configuration. When the arm 15c abuts on the fixed shaft 19, the rotation restricting member 15 And the spring pin 1 and the engaging portion 17 provided at the distal end of the arm portion 15a.
6 is released, and the pressure arm 13 connected via the link mechanism 18 is pushed up by raising the distal end side of the arm portion 15b, and the reverse roller 4 is moved to the outer peripheral surface of the feed roller 3. It is imposed. By starting the sheet feeding operation after setting the sheet feeding cassette 2 in the main body of the image forming apparatus, the sheet feeding direction is set in the sheet feeding direction in the same manner as in the embodiment described with reference to FIGS. The reverse roller 4 is rotated by the feed roller 3 that is driven to rotate, and the mainspring 1 is rotated.
2 is tightened, and a rotational force for rotating the reverse roller 4 in the direction opposite to the sheet feeding direction is stored. When two or more sheets 1 are fed into the nip between the feed roller 3 and the reverse roller 4, the reverse roller 4 rotates in the direction opposite to the sheet feeding direction by the rotational force stored in the mainspring 12. The sheet 1 is driven to prevent double feeding of the sheet 1. FIG. 4 shows a state in which the sheet cassette 2 is detached from the main body of the image forming apparatus. When the arm portion 15c separates from the fixed shaft 19, the rotation regulating member 15 rotates around the support shaft 14. , The engaging portion 17 provided at the tip of the arm portion 15a engages with the spring pin 16 to restrict the rotation of the reverse roller shaft 7. When the rotation restricting member 15 rotates in the direction of arrow c ', the distal end of the arm portion 15b writes, and when the pressing arm 13 connected via the link mechanism 18 is pulled down, the reverse roller 4 It has descended to a position away from 3. Therefore, when the sheet cassette 2 is detached from the image forming apparatus main body, the reverse roller 4 is separated from the feed roller 3, so that the reverse roller 4 and the feed roller 3 can be smoothly removed without rubbing. You. Here, when the reverse roller 4 separates from the feed roller 3 and the pressure acting on the reverse roller 4 from the feed roller 3 disappears, the rotational force stored in the mainspring 12 causes the reverse roller shaft 7 and the reverse roller shaft 7 to rotate. The rollers 4 and the like try to rotate in the direction opposite to the sheet feeding direction. However, substantially simultaneously with the separation of the reverse roller 4 from the feed roller 3, the engagement portion 17 engages with the spring pin 16 to restrict the rotation of the reverse roller shaft 7 and the reverse roller 4 in the direction opposite to the sheet feeding direction. . Accordingly, even when the reverse roller 4 is separated from the feed roller 3 as the sheet cassette 2 is removed from the image forming apparatus main body, the reverse roller 4 stored in the mainspring 12 is rotated in the direction opposite to the sheet feeding direction. The rotational force is maintained without being released. For this reason, immediately after the sheet feeding cassette 2 is set in the image forming apparatus main body and sheet feeding is started, two or more sheets of paper 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 mainspring 12, thereby preventing double feeding of the paper 1. As described above, the present invention relates to a feed roller which is driven to rotate in the sheet feeding direction, and a reverse roller which is supported by a reverse roller shaft via a torque limiter and which is circumscribed by the feed roller. A roller having a center end fixed to the reverse roller shaft, and the reverse roller shaft being wound and fastened when the reverse roller shaft is rotated together with the reverse roller in the paper feeding direction by the feed roller. A spring is provided to store the rotational force that rotates the paper in the direction opposite to the paper feeding direction.
A mechanism that rotates the reverse roller in the direction opposite to the paper feed direction when more than one sheet has entered to prevent double feeding of paper can be realized by a simple structure in which a spring is attached to the reverse roller shaft, and When the reverse roller is rotated by the rotational force stored in the mainspring, the reverse roller can be continuously rotated many times, so that three or more sheets enter the nip between the feed roller and the reverse roller. Even in this case, all the papers other than the paper in contact with the feed roller can be returned in the direction opposite to the paper feeding direction by continuously rotating the mainspring many times, completely preventing double feeding of papers. It has effects such as being able to. Further, mounting the reverse roller shaft and the torque limiter and the reverse roller to freely sheet cassette detachably attached to the image forming apparatus main body, the reverse roller due to the removal of the paper feed cassette from the image forming apparatus main body Since a rotation regulating member that regulates the rotation of the reverse roller shaft at the time of separation from the feed roller is provided,
When the paper cassette is detached from the image forming apparatus main body, the rotation of the reverse roller shaft can be regulated by the rotation regulating member, whereby the rotating force stored in the mainspring can be held without being released. And therefore,
Even if two or more sheets enter the nip between the feed roller and the reverse roller immediately after the paper cassette is set in the image forming apparatus main body and the paper is started, the reverse roller is stored in the spring. With the rotation force, the sheet can be rotated in the direction opposite to the sheet feeding direction. Therefore, the sheet feeding cassette can be prevented from being fed multiple times even immediately after it is set in the image forming apparatus main body.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing one embodiment of the present invention. FIG. 2 is a perspective view thereof. FIG. 3 is a front view showing a state in which a sheet cassette in another embodiment of the present invention is set in an image forming apparatus main body. FIG. 4 is a front view illustrating a state in which the sheet cassette is removed from the image forming apparatus main body. 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 enter a nip portion between the feed roller and the reverse roller. [Description of Signs] 2 Paper feed cassette 3 Feed roller 4 Reverse roller 6 Torque limiter 7 Reverse roller shaft 12 Spring spring 15 Rotation regulating member

Claims (1)

(57) [Claim 1] A feed roller which is driven to rotate in a sheet feeding direction, and a reverse roller which is supported by a reverse roller shaft via a torque limiter and which is circumscribed by the feed roller. In the sheet feeding device having the reverse roller, the center end is fixed to the reverse roller shaft, and the reverse roller shaft is wound together with the reverse roller in the paper feeding direction by the feed roller to feed the reverse roller. A mainspring that stores a rotational force that rotates in the direction opposite to the paper direction is provided , and is attached to the image forming apparatus main body.
The reverse roller shaft and the
Attach a lucr limiter and the reverse roller, and
For removing the paper cassette from the main body of the image forming apparatus
The separation of the reverse roller from the feed roller
Restriction of rotation for restricting rotation of the reverse roller shaft at the time of reverse
A sheet feeding device comprising a member.