JP3389688B2 - Paper feeder of image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device arranged in a sheet feeding portion of an image forming apparatus such as an electrophotographic copying machine, and more particularly,
The present invention relates to a device for preventing a roller member of a paper separating device from being worn at a paper nip position of a paper separating device, by causing a succeeding paper to slightly protrude after a fed paper.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, a paper accommodating means such as a plurality of paper feeding trays is arranged in a paper feeding portion, and the size of the paper feeding tray or the like is increased. A mechanism is configured in which sheets of different types are accommodated and the required sheets are sent out in accordance with the size and reduction ratio of the document. The paper feeding device arranged on the paper feeding tray is provided with a combination of a pickup roller for feeding the paper from the tray and a paper separating device arranged downstream of the paper feeding unit, and the paper feeding device is fed through the paper feeding device. The formed sheet is fed toward the image recording unit by the conveyance roller device arranged in the sheet conveyance path. In the paper feeding device, for example, as shown in Japanese Patent Publication No. 2-58178, a paper separating device is configured by combining a feed roller and a retard roller, and when feeding a paper from a tray, the feed roller is used. A means for driving the retard roller in the direction opposite to the paper feeding direction is provided while driving in the paper feeding direction. Further, in the above-mentioned conventional example, since the retard roller is driven in the direction opposite to the paper feeding direction, when the feed roller in contact with the retard roller circulates in the direction opposite to the paper feeding direction after feeding the paper, A means is provided to prevent the sheet from being excessively returned toward the tray.

Apart from the above-mentioned conventional example, for example, Japanese Unexamined Patent Publication No.
In the example shown in Japanese Patent No. 231324 or the like, a sheet feeding device as shown in FIG. 11 is configured. In the example shown in FIG. 11, the rear end portion of the paper P stored in the paper feed tray 1 is regulated by the end guide 7, and the bottom plate 2 is swingably provided via the drive shaft 6. And means for positioning the upper surface of the sheet toward the pickup roller 13 of the sheet feeding device 11 by raising the sheet. And
In order to regulate the rising position of the sheet, the sheet height detection sensor S is arranged to regulate the rotation operation of the lift means with respect to the drive shaft 6. Further, the paper feed tray 1
Guides along the guide rails 4 arranged on the frame 3 of the sheet feeding unit of the image forming apparatus. The sheet feeding tray is inserted from the front side of the apparatus main body, and the direction perpendicular to the inserting direction of the sheet feeding tray. It constitutes a mechanism for feeding the paper toward.

In the paper feeding unit 10 arranged in the main body frame of the image forming apparatus in correspondence with the paper feeding tray 1,
A feed roller 20 and a pickup roller 13 are arranged using the support bracket 12, and a drive mechanism for transmitting the driving force transmitted to the shaft of the feed roller 20 to the pickup roller 13 via a gear device is arranged. Further, the retard roller 30 which constitutes the paper separating device is
The retard roller 3 is arranged so as to face the feed roller 20 and is driven by a drive mechanism for the feed roller 3.
A mechanism for driving 0 in the direction opposite to the paper feeding direction is configured. The bracket 15 for supporting the retard roller 30 is supported on the main body frame by using a support shaft 16, and a spring 17 sets a force for pressing the retard roller against the feed roller. Then, by the sheet feeding device configured as described above, the sheet fed from the sheet feeding tray 1 is conveyed toward the image recording section by the conveying roller device 18 arranged in the sheet conveying path.

[0005]

In the paper feeding device of the image forming apparatus constructed as described above, when the paper is fed from the paper feeding tray, as shown in FIG. 12, the pickup roller 13 and the feed roller 13 are provided. 20 is driven in the paper feeding direction, and the retard roller 30 is driven in the opposite direction. Then, following the paper P sent out, 2
When the sheet P1 of the second sheet plunges into the nip position of the sheet separating device 14, the second sheet P1 is returned to the tray, and the sheet is sent out in the double feed state toward the sheet conveying path. Be able to prevent that. Further, in the above-mentioned paper separating device, a torque limiter or the like is provided on the axis of the retard roller so that the retard roller 30 can follow the rotation of the feed roller when one sheet is being conveyed. . Therefore, the roller members of the feed roller and the retard roller are prevented from wearing due to excessive friction in a state where the paper is normally separated.

In the paper feeding device, as shown in FIG. 13, the leading end of the fed paper is the paper separating device 14
In the state where the sheet is moved to the nip position of the transport roller device 18 and is transported by the transport roller device, control is performed so as to stop the driving action on the sheet separating device. This is because by extending the life of the roller member without performing extra drive on the paper separating device and by exhibiting a conveying action for the paper between the conveying roller device and the paper separating device, It is also to prevent energy consumption. Further, in that state, the feed roller is allowed to freely rotate following the paper, but the rotation of the retard roller is not set to be free, and the rotation in the paper feeding direction is prevented, so that the second paper is rotated. Does not pass through the portion of the sheet separating device following the first sheet.

However, in the state shown in FIG. 13, when the leading edge of the second sheet P1 is stopped immediately before the nip position of the sheet separating device, the sheet P is conveyed, and the retard is retarded. Since the paper strongly slides and moves with respect to the rollers, the roller members often wear. Further, the paper strongly slides on the retard roller, which causes a problem such as chattering noise, which is one of the causes of noise generated from the image forming apparatus. Other,
The resistance of the paper separating device is applied as an extra load to the transport roller device arranged in the paper transport path, which greatly affects the configuration of the drive mechanism for the transport roller device.

[0008]

It is an object of the present invention to solve the above-mentioned problems of the conventional paper separating device, in which the paper is conveyed by the conveying roller device at the downstream portion of the paper separating device.
A mechanism is provided to allow the retard roller to rotate slightly in the paper feed direction when the drive of the paper sorting device is stopped, and the leading edge of the second sheet is pushed into the nip position of the paper sorting device. By feeding out the paper of the eye, it is possible to prevent the paper from sliding directly on the roller member of the retard roller and prevent abrasion of the roller member. It is an object of the present invention to provide a means for preventing the leading edge of the second sheet from remaining at the nip position by returning to the above.

[0009]

The present invention relates to a sheet feeding device of an image forming apparatus, and the invention of claim 1 is directed to a sheet feeding portion from a sheet storing means such as a sheet feeding tray in a sheet feeding direction. In the drive transmission mechanism provided in the paper separating device, the rotating feed roller and the retard roller for applying a driving torque in the opposite direction to the paper feeding direction are arranged to face each other, and the drive path of the retard roller is provided. A one-way clutch for preventing rotation of the roller member in the sheet feeding direction is disposed on the one-way clutch, and means for permitting rotation of the one-way clutch at a minute angle is provided between the one-way clutch and a support member disposed at a fixed position. The means for permitting the clutch to rotate at a small angle includes a protruding member of a one-way clutch arranged with respect to the shaft of the feed roller, Than the projection member Eikuratchi inserted into the supporting hole of the fixed support member configured as a broad pore width,
A projecting member configured to have a width narrower than the support hole of the fixed support member is provided as a member allowing the rotation of a minute angle inside the support hole, and the action of conveying the paper in the paper feeding device is stopped. In this state, a spring that returns the one-way clutch to the drive start position is provided in combination, and the feed roller is rotated in the paper feed direction after the reverse drive of the retard roller is stopped.

According to the second aspect of the present invention, the drive motor is driven in the forward direction to drive the roller device of the paper feed section, and the motor is driven in reverse to raise the paper stored in the paper feed tray. Means for driving the means, means for transmitting the drive motor to the sheet raising means of the paper feed tray, which does not transmit the reverse rotation of the minute angle of the drive motor, and after stopping the normal rotation of the drive motor. It is characterized in that a driving means for performing a reversing operation of a minute angle is provided.

[0011]

In the sheet feeding device of the image forming apparatus of the present invention configured as described above, the one-way clutch is arranged in the middle of the path for transmitting the driving force from the feed roller to the retard roller, and the one-way clutch is provided. A means for allowing the retard roller to rotate a minute angle in the paper feeding direction is provided. Also, after the retard roller has rotated in the moving direction of the paper by a small angle, when the paper has finished passing,
Since the retard roller can be returned to the driving position by the action of the spring or the like, it is prevented that the paper remains at the nip position of the paper separating device and adversely affects the next paper feeding operation. .

Further, in the drive unit for the sheet separating apparatus of the present invention, the means for driving the motor in the reverse direction by the minute angle is provided, and the means for allowing the play provided in the drive transmission mechanism is used, so that only the minute angle of the motor can be controlled. It is possible to configure a device that causes only the retard roller to rotate in reverse during rotation. Then, when the paper is sent out, the retard roller is slightly reversely rotated, so that the subsequent paper can be pushed into the nip position of the paper separating device, and the paper sent out can be prevented from sliding with respect to the retard roller. To do so. Therefore, in the present invention, when the sheet is conveyed by the conveying roller device arranged at the downstream of the sheet separating device, the retard roller slides excessively on the sheet even if the driving of the sheet separating device is cut off. As a result, the wear of the roller member can be reduced and the generation of noise can be suppressed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet feeding device of an image forming apparatus according to the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 is the paper feeding device configured as shown in FIG.
The structure of the member and the drive transmission mechanism arrange | positioned at a paper separating device is shown. In the example shown in FIG. 1, the paper separating device 14 includes a feed roller 20 and a retard roller 3
0s are arranged to face each other. Further, the feed roller 20 has a one-way clutch 2 with respect to the shaft 22.
And a mechanism for transmitting a driving force via the shaft 22.
Is configured as an input shaft of a driving force for the sheet separating device, and another gear member 26 provided on the shaft 22 is used to configure a drive transmission unit for the pickup roller. Further, a torque limiter 31 is provided on the shaft 32 supporting the retard roller 30 to configure a mechanism that allows the retard roller 30 to rotate only in one direction. A driving force transmission device 25 is arranged at the ends of the two roller shafts 22 and 32, and a gear member 26 provided on the shaft 22 and a shaft 32.
The idler gear 27 is arranged between the gear members 28.

In the drive transmission mechanism, a one-way clutch 33 for transmitting drive to the retard roller is arranged on the shaft 22 of the feed roller, and a projecting member 34 provided integrally with the one-way clutch 33 is fixedly supported. The one-way clutch 33 is accommodated in the support hole 36 of the member 35, and is rotatably provided at a minute angle. As shown in FIGS. 2 and 3, the fixed support member 35 is provided at a fixed position with respect to the main body frame of the sheet feeding device.
The protruding member 34 of the one-way clutch 33 arranged with respect to the shaft 22 of the feed roller is inserted into the support hole 36 of the fixed support member 35 so that the one-way clutch can be rotated by a predetermined angle. The support hole 36 provided in the fixed support member 35 has a shape in which linear portions are arranged on both sides of a circular member, and is configured as a hole wider than the projecting member 34 of the one-way clutch 33, and is wider than the support hole. The protruding member 34 configured to have a narrow shape is rotatable inside the support hole between a position shown by a solid line in FIG. 2 and a position shown by a chain line. Further, a bracket 37 is provided on the one-way clutch 33, and a spring 38 is provided between the bracket 37 and the main body of the fixed support member to automatically return the one-way clutch to the retard roller driving state. is doing.

In the paper feeding apparatus of the present invention constructed as described above, when the paper is fed while being fed, as shown by the arrow in FIG. 1, the feed roller 20 and the retard roller 30 are provided.
Are rotated in the same direction with respect to their respective axes, and the paper is fed while separating the paper between both roller members. When the paper is fed by the paper feeding device, the driving force of the feed roller shaft 22 is transmitted through the one-way clutch 21 so that the feed roller rotates in the paper feeding direction, but is driven with respect to the shaft 22. The retard roller 30 driven via the force transmission device 25 is driven via the torque limiter 31 in the direction opposite to the paper feeding direction. When two or more sheets are inserted between the two roller members, the feed roller 20 feeds the upper sheet, but the lower sheet is fed by the retard roller 30 in the opposite direction to the sheet feeding direction. By being rotated in the direction, it is returned toward the tray.
Further, when only one sheet of paper is conveyed between both roller members, the torque limiter 31 provided between the retard roller 30 and the shaft 32 slides, so that the retard roller 30 rotates in a state of rotating around the sheet. .

Then, in a state where the leading end of the sheet is nipped by the downstream transport roller device, the shaft 22 of the feed roller is
Is stopped and the state is switched to the state of paper feeding by the conveying roller device. At that time, the sheet conveyed by the conveying roller device rotates the feed roller 20 provided via the one-way clutch in the sheet feeding direction. However, since the retard roller 30 has the shaft and the driving force transmitting device in a stopped state, , It cannot rotate following the movement of paper.
However, the retard roller 30, which is in contact with the paper at a predetermined pressure, receives the force of the paper being conveyed by the conveyance roller device, and therefore, the one-way clutch 33 for transmitting the drive to the retard roller provided on the shaft 22 is provided. It is rotated from the state shown by the solid line in FIG. 2 to the state shown by the chain line.
When the retard roller rotates as described above, the second sheet that has been stopped with the leading end in contact with the retard roller enters the nip position of both roller members, and the second sheet is retarded. The sheet feeding operation for the first sheet conveyed by the conveying roller device is performed so as to stop at the nip position. Therefore, while the sheet is being fed by the transport roller device, as shown in FIG. 4, the second sheet P1 is in a state of protecting the surface of the retard roller, and the surface of the retard roller at the nip position is the sheet to be transported. It is prevented from sliding directly on.

As described above, the projecting member 34 provided on the shaft of the retard roller is stopped and held at the position shown by the chain line in FIG. 2 and the spring 38 extends until the paper leaves the nip position of both roller members. Held in a state. When the first sheet of paper comes out of the nip position of the sheet separating device, the driving of the feed roller in the sheet feeding direction is released, but the second sheet of paper P1 remains between both roller members. There is. Therefore, when the state in which the feed roller is driven by the paper ends, the force of the spring 38 of the drive system with respect to the retard roller 30 exerts an action of returning the retard roller 30 to the original position.
When the one-way clutch 33 is rotated by the spring 38, the protrusion member 34 of the one-way clutch 33 is rotated.
Is returned from the position shown by the chain line in FIG. 2 to the position shown by the solid line, and the paper P1 that has entered the nip position of both rollers is
By the reverse rotation of the retard roller, it is returned from the nip position toward the tray. Therefore, after the paper is sent out by the transport roller device and the first paper is sent out from the nip position of the paper separating device, no paper remains in the paper separating device, so the pickup roller is driven at the next paper feeding. Then, it is possible to newly take out the paper from the tray and send it out toward the paper separating device.

In the paper feeding device, the returning means provided in the one-way clutch 33 corresponding to the retard roller is
Disposing a spring 38 between the protruding member 34 and the fixed support member 35, as shown in FIGS.
It can be easily configured by providing the guide means by the combination of the support hole and the projecting member in which the arcuate sliding portion and the linear regulating portion are combined. Further, the angle that allows a minute rotation with respect to the retard roller can be arbitrarily set depending on the shape such as the width of the protruding member and the support hole, and the thickness of both members can be set as necessary. it can. Further, in the present invention, the mechanism for allowing a minute rotation with respect to the retard roller and the mechanism for returning the retard roller to the original position after the paper passes,
It can also be implemented by using means having other configurations.

[0019]

Second Embodiment Apart from the above embodiment, in the present invention,
As shown in FIGS. 5 to 7, a mechanism that allows a minute rotation of the retard roller can be incorporated in the driving force transmission device. In the example shown in FIG. 5, the feed roller 20 that constitutes the sheet separating device 14 is used.
The retard roller 30 and the retard roller 30 are provided with a one-way clutch 21 and a torque limiter 31 between the retard roller 30 and the retard roller 30 to regulate the rotation of each roller member. A driving force transmission device 25, which is a combination of a plurality of gear members 26 to 28, is arranged at the ends of the shafts 22 and 32 of the two rollers 20 and 30. The roller member is rotated in the same manner as in the state shown in FIG. In the driving force transmission device 25, the one-way clutch 40 is arranged with respect to the idler gear 27, and the transmission of the driving force to the retard roller is controlled.

The one-way clutch 40 provided on the gear 27 is constructed as shown in FIGS. 6 and 7, and the gear 27 and the one-way clutch 40 are supported by a fixed shaft 42 provided on the body frame 3. In addition, the one-way clutch 40 has a protruding member 4 that faces the gear side.
1 is provided so as to project, an opening 46 is arranged in the receiving member 45 of the gear 27, and only the distance between the walls on both sides of the opening 46,
A mechanism that allows the movement of the protruding member 41 is configured.
Although not shown in FIG. 7, a return spring can be arranged on the one-way clutch as shown in FIG. 3 to perform a return action on the retard roller. Can also be configured by combining arbitrary members.

In the sheet separating apparatus shown in FIGS. 5 to 7, when the sheet is being fed while being separated, the projecting member 41 of the one-way clutch 40 and the receiving member 45 are driven by the driving force transmitted from the shaft of the feed roller. The rotation with respect to the idler gear 27 is transmitted in a state of being caused by the one side of the opening 46. On the other hand, in the state where the sheet is conveyed by the conveying roller device at the downstream portion and the driving of the sheet separating device is stopped, the projecting member 41 is positioned at the other side of the opening 46 by the driving force of the sheet with respect to the retard roller. Stop. Then, after the trailing edge of the sheet has passed through the nip position of the sheet separating device, the projecting member 41 is returned to the center of the opening or the driving position to cope with the conveyance of the next sheet, and as shown in FIG. A paper transport action as shown can be performed.

[0022]

Third Embodiment In addition to the example shown in FIG. 1, in the present invention, as shown in FIG.
A one-way clutch 33 may be arranged with respect to the shaft 32, and means may be provided corresponding to the one-way clutch 33 to allow rotation at a minute angle. In the example shown in FIG. 8, the sheet separating device 14 is configured by disposing the feed roller 20 and the retard roller 30 so as to face each other. Further, the feed roller 20 constitutes a mechanism for transmitting a driving force to a shaft 22 via a one-way clutch 21, and the shaft 22 constitutes an input shaft of a driving force for a sheet separating device, and a drive transmission for a pickup roller. Constitutes a means. Further, a torque limiter 31 is provided on the shaft 32 supporting the retard roller 30 to configure a mechanism that allows the retard roller 30 to rotate only in one direction.

A one-way clutch 33 is arranged on the shaft 32 of the retard roller 30, and a projecting member 34 provided integrally with the one-way clutch 33 is accommodated in a support hole 36 of a fixed support member 35. The one-way clutch 33 is provided so as to be rotatable by a minute angle. The fixed support member 35 can be configured in the same manner as that shown in FIGS. Then, the projecting member 34 of the one-way clutch 33 arranged with respect to the shaft 32 of the retard roller is inserted into the support hole 36 of the fixed support member 35 so that the one-way clutch can be rotated by a predetermined angle. The support hole 36 provided in the fixed support member 35 has a shape in which linear portions are arranged on both sides of a circular member, and is configured as a hole wider than the projecting member 34 of the one-way clutch 33, and is wider than the support hole. The protruding member 34 configured to have a narrower shape is located inside the support hole as indicated by the solid line in FIG.
It is allowed to rotate between the positions shown by the dashed lines.

In the sheet feeding device of the present invention constructed as described above, when the sheet is fed while being fed, as shown by the arrow in FIG. 8, the feed roller 20 and the retard roller 30 are provided.
Are rotated in the same direction with respect to their respective axes, and the paper is fed while separating the paper between both roller members. When the paper is fed by the paper feeding device, the driving force of the feed roller shaft 22 is transmitted through the one-way clutch 21 so that the feed roller rotates in the paper feeding direction, but is driven with respect to the shaft 22. The retard roller 30 driven via the force transmission device 25 is driven via the torque limiter 31 in the direction opposite to the paper feeding direction.

When two or more sheets are inserted between the two roller members, the upper sheet is fed by the feed roller 20, but the lower sheet is fed by the retard roller 30 in the sheet feeding direction. And is rotated in the opposite direction, and is returned toward the tray. Further, when only one sheet is conveyed between both roller members, the torque limiter 31 provided between the retard roller 30 and the shaft 32 slides, so that the retard roller 30 rotates in a state of rotating around the sheet. This is performed in the same manner as in the case of the device shown in FIG. Therefore, as shown in FIG.
Even when the drive transmission mechanism for the sheet separating device is configured, the sheet separating operation can be performed in the state shown in FIG.

In addition to the example shown in FIG. 8, the drive transmission mechanism shown in FIG. 9 can be constructed in the present invention. In the example shown in FIG. 9, the motor 5
0 shows a case in which a mechanism for driving the roller member of the paper feeding device and means for raising the paper stored in the paper feeding tray is configured by using 0. In the drive transmission mechanism, two gears 52 and 53 are provided on the output shaft 51 of the motor 50, and the drive transmission is transmitted to the gear device 55 by the gear 52, and the other gear 53 is fed to the feed roller via the transmission device 65. It constitutes means for transmitting drive to the shaft 22 of the. The gear device 55 that transmits the drive by the gear 52 transmits the drive to the shaft 32 of the retard roller 30 via the one end gear 56, and the other end gear 58 swings the lift means 5. Constitutes a means for performing.

In the gear device 55, an end gear 56 meshing with the gear 52 has a coupling member 57 arranged between it and a one-way clutch 60 arranged at the end of the shaft 32. As shown in FIG. 8 and the like, when transmitting the rotation, the drive transmission mechanism is configured in a state in which there is some play. The one-way clutch 61 is attached to the shaft 32 of the retard roller 30.
And a torque limiter 62 are arranged, and of the two one-way clutches 60, 61 and the torque limiter 62, the one-way clutch 60 transmits the driving force of the end gear 56 to the shaft when performing the feeding operation. The other one-way clutch 61 constitutes a means for locking the retard roller when the retard roller is reversely driven. Further, the torque limiter 62 can allow the retard roller 30 to rotate following the sheet in a state where only one sheet is nipped at the nip position of the sheet separating device when performing the sheet separating operation. It is used to perform the action. When the motor 50 is normally rotated, the transmission gear device 6 drives the shaft 32 in one direction.
3 to the retard roller 30 so that the retard roller can perform the paper separating action in a good state.

When the retard roller 30 is driven, the drive roller shaft 22 also transmits the drive in synchronization with the retard roller, and feeds the paper fed from the paper feed tray while performing a separating action. To be able to perform an action. A one-way clutch is arranged on the shaft 22 of the feed roller to prevent the driving force from being transmitted when the motor is driven in the reverse direction, thereby forming a driving means similar to that shown in each of the embodiments. Further, although not described in FIG. 9, a drive transmission means for the pickup roller is arranged with respect to the drive means for the feed roller to constitute a means for driving the feed roller and the pickup roller in synchronization.

The gear device 55 constitutes means for transmitting the drive force to the lift means 5 via the end gear 58 by performing the reverse drive of the motor 50. The drive shaft 6 of the lift means 5 is connected to the transmission device 70 via a one-way clutch 71, and a coupling member 59 is arranged between the end gears of the transmission device 70. The coupling member 59 is configured to allow rotation of a small angle when transmitting drive. Further, the one-way clutch 71 arranged on the drive shaft 6 of the lift means constitutes a mechanism for transmitting the drive force to the shaft 6 only when the motor rotates in the reverse direction. Therefore, in the device in which the drive is transmitted by the motor 50 via the gear device 55, the roller member of the paper feeding device is driven when the motor rotates in the normal direction to perform the operation of feeding the paper toward the paper transport path while separating the paper. In the state in which the motor is rotated in the reverse direction, the lift means 5 is driven, and the bottom plate or the like of the paper feed tray is lifted by the lift means 5 to position the paper in correspondence with the pickup roller of the paper feed device. it can.

In the drive transmission mechanism for the sheet feeding device constructed as described above, the drive corresponding to the retard roller 30 is performed to perform the sheet separating action, and the sheet is temporarily sent to a predetermined position on the sheet conveying path. Stop.
Then, for example, in a state where the leading end portion of the sheet is nipped by the conveyance roller device arranged in the downstream portion of the sheet feeding device, the motor 5
0 is driven in the reverse direction by a small angle. In addition, the drive transmission mechanism for the retard roller 30 is provided with an action of driving the retard roller 30 in the reverse direction, but the play between the coupling member 57 and the one-way clutch 60 and the support body of the one-way clutch 61 are provided. Due to the backlash, the retard roller 30 is reversed by a minute angle, and the leading edge of the sheet under the sheet being sent out rushes into the nip position of the sheet separating device by the minute rotation of the retard roller, as shown in FIG. In this state, the surface of the retard roller is covered so as to perform a guiding action when the preceding paper is sent out. When the paper is fed out as described above, and the paper is conveyed by the conveyance roller device arranged in the downstream portion of the paper feeding device, and the trailing end of the paper leaves the nip position of the paper separating device, The paper resistance to the retard roller is eliminated. Then, when the rotation action of the retard roller by the paper is stopped, the action of the return mechanism incorporated in the one-way clutch causes the retard roller to return the paper at the nip position toward the paper feed tray, and When the leading edge is pulled out from the nip position of the sheet separating device, the apparatus stands by in a state where the next sheet can be fed.

When the motor is driven in the reverse direction, since the rotation angle is small, the drive transmission mechanism for the lift means 5 is in a state in which drive is not transmitted to the lift means due to the backlash of the coupling member 59. . Therefore, in the coupling member 59 provided in the end gear 58 of the gear device 55, there is a mechanism for giving a play so as not to give a swinging action to the lift means when the coupling member 59 is reversed by a slight angle with respect to the retard roller. Is configured. Further, in order to raise the paper in the paper feed tray between the paper feeding operations, the time for which the motor 50 is driven in the reverse direction is extended to detect the paper height which is arranged corresponding to the paper feed tray. When the sensor detects the rise of the paper and outputs a signal to the control device to stop the movement of the paper rise,
Stop the reverse rotation of the motor.

In the apparatus of the present invention constructed as described above, as shown in the graph of FIG. 10, the relationship between the rotation angle of the retard roller, the worn state of the roller, and the double feed occurrence rate has been found. In the graph, the relationship between the rotation angle of the retard roller and the amount of wear of the roller is as shown by the curve a, and the double feed occurrence rate is as shown by the curve b. In other words, the smaller the rotation angle of the retard roller, the greater the amount of wear of the roller, and in inverse proportion to this, the double feed occurrence rate increases. In the present invention, it has been found that two conditions, that is, the amount of wear of the retard roller and the double feed occurrence rate, can be satisfied within the range in which the rotation angle of the retard roller is in the range of 2 ° to 20 °. Therefore, in each of the first and second embodiments of the present invention, the device that allows the rotation of the retard roller may be configured with a means that allows the rotation of the retard roller with respect to the shaft within the range of the allowable angle. it can.

[0033]

Since the sheet feeding device of the image forming apparatus of the present invention is configured as described above, the drive transmission mechanism of the sheet feeding device allows the minute rotation of the retard roller. By providing the mechanism, it is possible to reduce the wear of the rollers and reduce the double feed occurrence rate. Further, in the present invention, the retard roller drive transmission mechanism is provided with a one-way clutch and means for permitting rotation of a minute angle, and the retard roller is moved after the trailing edge of the sheet has passed through the nip position of the sheet separating device. Only by providing the means for returning to the original position, the operation of the paper separating apparatus can be exhibited in good condition. Then, after the retard roller is rotated by the paper, when the paper has finished passing, the retard roller can be returned to the drive position by the action of the spring or the like, so that the paper remains at the nip position of the paper separating device, There is no adverse effect on the next paper feed.

In addition to the above effects, in the present invention, the drive motor for the sheet feeding device is configured to be switchable in the forward and reverse directions, and is configured to perform the operation of reversing the motor by a minute angle. You can Then, at the nip position of the paper separating device, the leading end of the succeeding paper can be pushed in to cover the retard roller, and the paper feeding operation can be performed. In that case, the paper separating device can be used. It is possible to easily control the reverse rotation operation of the roller device and the normal rotation operation at the time of sheet feeding.
Therefore, in the present invention, when the sheet is conveyed by the conveying roller device arranged at the downstream of the sheet separating device, the retard roller slides excessively on the sheet even if the driving of the sheet separating device is cut off. Therefore, it is possible to reduce the wear of the roller member and suppress the generation of noise.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a paper separating apparatus of the present invention.

FIG. 2 is a front view of a mechanism for restricting rotation of the one-way clutch of the present invention.

FIG. 3 is an explanatory diagram of a mechanism for returning the one-way clutch.

FIG. 4 is an explanatory diagram of a sheet conveyance state by the sheet feeding device of the present invention.

FIG. 5 is a perspective view of a second embodiment of the present invention.

FIG. 6 is a side view of a mechanism for restricting rotation of the one-way clutch provided in FIG.

FIG. 7 is an explanatory view of the mechanism of FIG. 6 as seen from the front.

FIG. 8 is an explanatory diagram of an example in which a drive transmission mechanism for the retard roller is provided with a unit that allows rotation of the one-way clutch at a minute angle.

FIG. 9 is an explanatory diagram showing the configuration of another embodiment of the present invention.

FIG. 10 is a graph showing the relationship between the abrasion amount of the retard roller and the double feed occurrence rate in the device of the present invention.

FIG. 11 is an explanatory diagram of a sheet feeding device used in a general image forming apparatus.

FIG. 12 is an explanatory diagram of a paper feeding operation in a conventional paper feeding device.

FIG. 13 is an explanatory diagram of a state in which a sheet is conveyed by a conveying roller device at a downstream portion.

[Explanation of symbols]

1 paper feed tray, 10 paper feed unit, 11
Paper feeder, 13 Pickup roller, 14
Paper separating device, 20 Feed rollers, 21
One-way clutch, 22 shafts, 25 driving force transmission device, 30 retard roller, 31 torque limiter, 32 shafts, 33 one-way clutch, 34 projecting member, 35 fixed support member, 3
6 support holes, 40 one-way clutch, 41
Projecting member, 45 receiving member, 46 opening, 5
0 motor, 55 gear device, 56/58 end gear, 57/59 coupling member, 60/6
1.71 one-way clutch, 62 torque limiter.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65H 3/52 330 B65H 5/06 G03G 15/00 516

Claims (2)

(57) [Claims] 1. A feed roller that rotates in a paper feeding direction in a paper feeding section from a paper accommodating unit such as a paper feeding tray.
A retarding roller that applies a drive torque in a direction opposite to the paper feeding direction is arranged so as to face each other to configure a paper separating device, and in a drive transmission mechanism provided in the paper separating device, a roller member is fed to a drive path of the retard roller. A one-way clutch for preventing rotation in a direction is arranged, and means for permitting rotation of the one-way clutch at a minute angle is provided between the one-way clutch and a support member arranged at a fixed position. Means for allowing the protruding member of the one-way clutch arranged with respect to the axis of the feed roller to be inserted into a support hole of a fixed support member configured as a hole wider than the protruding member of the one-way clutch, The protruding member, which has a shape narrower than the support hole of the support member, enables rotation of a minute angle inside the support hole. Provided as to volume, with the conveying action of the paper in the paper feeding device is stopped,
A sheet feeding device of an image forming apparatus, wherein a spring for returning a one-way clutch to a drive start position is provided in combination, and the feed roller is rotated in a sheet feeding direction after stop of reverse driving of the retard roller. 2. A means for driving a roller device of a paper feeding section by driving a drive motor in a forward direction and a means for driving a means for raising a paper stored in a paper feeding tray by driving the motor in a reverse direction. Is provided to the drive transmission mechanism for the sheet raising means of the paper feed tray, the transmission means not transmitting the reverse rotation of the minute angle of the drive motor, and the reverse rotation of the minute angle after the forward rotation of the drive motor is stopped. The sheet feeding device of the image forming apparatus according to claim 1, further comprising a driving unit that performs an operation.