JPH07285688A - Paper feeding device for image forming device - Google Patents

Abstract

PURPOSE:To arrange a reverse rotation preventing member against the drive shaft of a feed roller of a paper separation means, accurately retaining the stop position with the shaft being stopped, prevent the roller from rotating due to the reacting force of paper loop or the like, and enabling resistration operation to be done. CONSTITUTION:In a paper feeding device l for feeding out paper sheets from a paper sheet tray in a paper feeding part of an image forming device, registration roller means is arranged downstream from paper separation means 3, and means for facilitating matching to paper sheets between the means 3 and the resitration means is provided. In the paper separation means a one-way clutch 21 and the like is arranged as a reverse rotation preventing member 22 with respect to a feed roller shaft 20 driven by a driver 40 in the paper separation means 3, and thus the shaft is prevented from rotating by the moving direction force under a state that a feed roller 4 is stopped to facilitate a good condition of paper tip positioning action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, which feeds sheets one by one from a sheet accommodating means such as a sheet feeding tray by using a sheet feeding device, and a sheet separating device and a registration roller. The present invention relates to an apparatus for aligning sheets between apparatuses, and particularly when a sheet fed from a sheet feeding apparatus is locked by a registration roller apparatus to form a loop,
The present invention relates to a device that prevents a roller member of a paper separating device from reversing due to the stiffness of a paper and enables accurate positioning of the leading end of the 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 sheet accommodating means such as a sheet feeding tray is arranged in a sheet feeding section, and sheets accommodated in the sheet feeding tray are arranged. It uses a mechanism that feeds paper from the above one while separating it with a paper feeding device. As a sheet feeding device arranged on the sheet feeding tray, a relatively large image forming apparatus such as that disclosed in Japanese Patent Laid-Open No. 2-231324 is used. In the image forming apparatus shown in the above conventional example, a plurality of paper feed trays are arranged in a stack at the lower part of the main body of the apparatus, and the paper feed devices arranged for the respective paper feed trays are used to form a paper feed path. It constitutes a mechanism for feeding the paper toward. Then, the sheet sent out from the sheet feeding tray toward the sheet conveying path is subjected to the aligning action by the sheet aligning device arranged immediately before the position where the image from the photosensitive drum is transferred, and then the image transfer section. Will be sent to.

In addition to the sheet feeding device provided in the image forming apparatus, in a relatively small-sized image forming apparatus, a registration roller device arranged in a position close to a sheet feeding device arranged in a sheet feeding tray. In some cases, a paper aligning operation is performed between the paper separating devices so that an image can be immediately transferred to the paper delivered from the paper feed tray. In the apparatus such as the small electrophotographic copying machine as described above, a sheet feeding device for a sheet feeding tray is generally configured as shown in FIG. In the paper feeding device, the paper P sent out by the pickup roller 2 arranged corresponding to the leading end on the paper feeding side with respect to the paper feeding tray 9 is fed between the feed roller 4 and the retard roller 5 of the paper separating device 3. It constitutes a mechanism for delivering the image to the registration roller device 7 in the downstream portion. When the paper is sent out from the paper feed tray, the leading end of the paper sent out by the pickup roller 2 is pushed into the nip portion of the paper separating device 3 to perform a separating operation, and the paper P sent out from the paper separating device is registered. The roller device 7 is pushed into the nip portion. Then, while the registration roller device is stopped, the feed roller 4 of the paper separating device is excessively rotated to form a loop Pr on the paper, and the reaction of the loop of the paper causes the reaction of the waist of the paper. Harnessing the power
The leading edge of the sheet is uniformly pressed against the nip portion of the registration roller device so that the aligning action can be exerted. Then, when the registration roller device 7 is driven to send the paper toward the image transfer portion, the registration roller device 7 conveys the paper with the leading end surface of the paper positioned at a right angle to the conveyance direction. It is possible to prevent the sheet from being bent at the image transfer portion.

[0004]

However, as shown in FIG. 6, in the case of a device that forms a loop between the paper separating device and the registration roller device to provide a matching action, the paper When the user is stiff, the reaction force of the loop may cause the paper to reverse the roller of the paper separating device. Such a problem is apt to occur, for example, when there is play in the meshing of the gear device of the drive diameter with respect to the feed roller, and the play roller is caused by the play in the meshing part of the gear device when the feed roller is stopped. This is because the state is slightly rotated. When the backlash described above occurs, the paper is thick paper, and when the paper is stiff, the leading edge of the paper comes from the nip part of the paper separating device due to the reaction force of the loop. It will be returned and the loop will become smaller. Also, when feeding the paper, if the leading edge of the paper moves forward with the feed roller rotating, the succeeding paper will also rush into the nip part of the paper separating device. When the rollers are operated and sent out toward the registration roller device 7 at the downstream portion, there is a problem that double feeding or the like is likely to occur.

In the general sheet aligning apparatus as shown in FIG. 6, as shown in the graph of FIG. 7, the feed roller 4 of the sheet separating apparatus rotates to feed the sheet, and after a predetermined time, the sheet is fed. The tip of the is detected by the sensor. After that, in a state in which the leading end of the sheet has entered the nip portion of the registration roller device 7 and stopped, the roller 4 performs an additional feeding operation to form a loop Pr on the sheet. Then, when the registration roller device 7 is driven to send the paper toward the image transfer portion, the rigidity of the loop of the paper is used to bring the leading end of the paper into the nip portion of the registration roller device. The sheet is made to enter and the conveying operation is performed with the leading edge of the sheet aligned. However, when the paper rolls back at the paper separating device due to the stiffness of the paper, the loop amount decreases by R1 with respect to the paper loop setting amount R according to the length of the paper retracted. Because
There is a problem in that the registration roller device is driven to shift the timing of feeding the paper. Also, in fact,
The fact that the paper moves backward in the paper separating device means that the leading edge of the paper is delayed from the set value when the registration roller device is driven to feed the paper, as shown by the chain line in the graph of FIG. The image transferred onto the paper will be displaced from the set position at the leading end.

In order to solve the above problems,
For example, as shown in Japanese Utility Model Publication No. 4-15727 and the like, incorporating a sheet reverse running preventing means is also one method. However, in the device as shown in the above-mentioned conventional example, since the reverse rotation preventing means is not arranged directly with respect to the feed roller shaft, a slight backlash may occur before the reverse rotation of the feed roller shaft is stopped. A rush is inevitable. Further, in the paper separating device as shown in FIG. 6, in the device in which the rotation of the retard roller shaft is made to follow the rotation of the feed roller shaft, the feed roller shaft is stopped and the downstream conveying roller device is used. Depending on the conveyed sheet, the retard roller is driven to rotate (reverse). In such a state, even if the next sheet enters the lower part of the sheet being sent, there is a problem that two sheets are sent out in the double-feed state as they are without adding a judgment action to the sheet. . Therefore, in order to solve the above-mentioned problem, it is possible to prevent the reverse rotation of the retard roller shaft by providing a means for preventing the reverse rotation of the feed roller shaft. If there is backlash, the degree of occurrence of double feeding of paper and feeding error will increase.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional sheet feeding device. By disposing the reverse rotation preventing means with respect to the feed roller shaft, the sheet separating device and the registration roller device are separated from each other. When aligning paper with, prevent the phenomenon that the feed roller reverses and the paper retracts due to the strength of the paper loop, and keeps the size of the loop formed on the paper at a constant value. It is an object of the present invention to provide an apparatus capable of preventing a registration error and performing an accurate paper feeding action.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a paper feeding device is constructed by combining a pickup roller arranged corresponding to a paper feeding portion of a paper feeding tray and a paper separating device arranged downstream of the pickup roller. Then, a registration roller device is arranged downstream of the paper feeding device to form a paper aligning device, the feed roller of the paper separating device is driven in the paper feeding direction, and the retard roller is used to feed the paper through a torque limiter. In addition to performing the paper separating operation by driving in the direction of returning to, the paper aligning operation is performed by forming a loop in the paper between the paper separating device and the registration roller device.
The present invention relates to a device for feeding a sheet by a transport roller device arranged in a downstream sheet transport path. In the present invention, the reverse rotation preventing member is arranged on the roller shaft for transmitting the drive to the feed roller, and the driving means for transmitting the driving force from the driving device through the reverse rotation preventing member is provided. Further, in the present invention, a one-way clutch for transmitting the rotation of the feed roller shaft to the feed roller together with the reverse rotation preventing member and a feed roller clutch for transmitting drive to the pickup roller are arranged on the feed roller shaft. A means for transmitting drive to the feed roller and the pickup roller can be configured via the feed roller clutch and the one-way clutch provided on the feed roller shaft.

[0009]

As described above, in the paper feeding device of the present invention,
A reverse rotation preventing member is arranged with respect to the feed roller shaft that drives the feed roller, so that even if there is play between the drive device and the gear device, backlash can be prevented from occurring while the feed roller is stopped. I am trying.
Further, in the sheet feeding device of the present invention, the reverse rotation preventing member is arranged directly with respect to the feed roller shaft, so that even if a force for rotating the feed roller is applied while the feed roller is stopped, It is possible to reliably maintain the roller in a stopped state. Therefore, even if the reaction force of the loop formed on the thick paper or the like exerts a strong force to reverse the feed roller, the feed roller can be held in a stopped state, so that the paper feed timing may be misaligned. Can be prevented. Further, the sheet feeding device of the present invention is provided only with a reverse rotation preventing member additionally provided on the feed roller shaft, and as the feed roller shaft, for example, a one-way type often used in conventional electrophotographic copying machines and the like. Since a clutch or the like can be used, the structure of the device is not complicated.

[0010]

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. As shown in FIG.
The sheet feeding device 1 of the present invention comprises a pickup roller 2 arranged on the upper front side of the sheet feeding portion of the sheet feeding tray 9 and a sheet separating device 3 arranged downstream thereof. The sheet sent by is fed toward the image transfer section by the registration roller device 7 arranged in the sheet conveying path. The pickup roller 2 is a support link 1
5, the support link 15 is swingably provided with respect to the feed roller shaft 20 of the feed roller 4, and an idle gear arranged between the gear of the pickup roller 2 and the gear of the feed roller 4. Drive is transmitted via 12. The retard roller 5 arranged at a position facing the feed roller 4 constituting the sheet separating device 3 has a retard roller shaft 30 supported by a support link 32, and the support link 32 supports the support shaft 33.
It is provided so as to be swingable through the spring, and the spring 34 pushes the retard roller toward the feed roller.

In the sheet feeding device 1 of the present invention configured as described above, by rotating the feed roller shaft 20, the pickup roller 2 is driven via the gear device,
Further, the shaft 30 of the retard roller 5 is driven in the opposite direction via an interlocking mechanism with the feed roller shaft 20. Therefore, the paper P picked up by the pickup roller 2 from the paper feed tray 9 is used as the paper separating device 3
Thus, the sheet can be fed toward the image transfer section while being fed by the registration roller device 7 in the downstream section. Further, when the registration roller device conveys the paper delivered from the paper separating device, the driving of the roller member of the paper separating device is stopped. The carrying action is performed. In the paper feeding device 1, the paper taken out from the paper feeding tray 9 by the pickup roller 2 is blown into the nip portion between the roller members of the paper separating device, and is separated by the feed roller of the paper separating device. By rotating the sheet in the sheet feeding direction, the sheet is sent toward the registration roller device 7. Then, in a state where the leading end portion of the sheet is projected into the nip portion of the registration roller device 7, the feeding action by the sheet separating device is continued for a predetermined time to form a loop on the sheet and the aligning action of the sheet is performed. .

In the paper feeding device as shown in FIG. 1, a driving device as shown in FIG. 2 can be constructed. In the driving device of the sheet feeding device shown in FIG. 2, the driving device 40 arranged outside the frame 8 of the main body of the device has an input gear 41 connected to another driving device, a feed roller shaft 20, and a retard roller shaft. A drive gear device 43 for 30 is arranged. Further, in the drive system of the sheet feeding device of the present invention, the feed clutch 23 is arranged between the transmission gear 42 corresponding to the feed roller shaft 20 and the feed roller shaft 20, and the reverse rotation preventing member 22 is provided at the base of the feed roller shaft 20. Are arranged to form a drive system for the feed roller 4. Further, the feed roller shaft 20
On the other hand, the feed roller 4 is provided via the one-way clutch 21, and when the feed roller 4 is driven, a mechanism for transmitting the rotation of the feed roller shaft 20 via the one-way clutch 21 is configured.

The pickup roller shaft 1 is connected to the feed roller shaft 20 via support links 15 and 15a.
0, and a pickup roller shaft 10 on which the pickup roller 2 is arranged, and a feed roller shaft 20.
The drive transmission mechanism by the gears 11 to 13 is arranged between
The pickup roller 2 can be driven. In the drive system for the pickup roller 2, drive transmission is performed to the drive gear 13 via the feed roller clutch arranged on the feed roller shaft. Therefore, via the feed clutch 23, the shaft 20
Rotation of the feed roller 4 causes the drive gear 1 to rotate.
Shaft 10 of pickup roller 2 through 3, 12, 11
Be transmitted to. Then, by driving the pickup roller and the feed roller in association with each other, the operation of feeding the paper from the paper feed tray can be continued.

With respect to the retard roller 5 arranged so as to face the feed roller 4, a means for driving the retard roller shaft 30 via the drive gear device 43 of the drive device 40 is constituted. A torque limiter 31 is arranged between the retard roller 5 and the retard roller shaft 30, and when the sheet sorting operation is performed, one sheet of paper is nipped by the sheet sorting device and the torque limiter 31 acts as a retard roller. Due to the large friction between the sheets,
The torque limiter 31 slides to cause the retard roller 5 to rotate following the sheet. Further, even when the retard roller is held at the stop position, if the action of rotating the retard roller in the rotation direction is added,
The retard roller can be rotated in a direction opposite to the rotation direction of the retard roller shaft following the movement of the paper.

In the drive system of the present invention constructed as described above, since the reverse rotation preventing member 22 is arranged directly with respect to the feed roller shaft, the action of stopping the feed roller shaft can be accurately performed. become. Further, in the state where the feed roller shaft 20 is stopped, the state in which the feed roller shaft 20 is stopped can be maintained even if the action of rotating the feed roller 4 is applied due to the reaction force of the paper contacting the feed roller. , Make it possible to set the paper stop position accurately. Further, in the apparatus of the present invention, when the registration roller device performs the action of pulling the paper toward the downstream portion with the feed roller shaft stopped, the one-way clutch 21 idles. It does not interfere with the feeding action of the paper by rotating it with respect to 20.

In addition to the example of the drive device shown in FIG. 2, the present invention may also be configured with a drive system as shown in FIG. In the example shown in FIG. 3, the reverse rotation preventing member 22 is arranged at the base of the feed roller shaft 20, and the feed roller shaft 20 and the transmission gear 42 are arranged.
A drive transmission means using a feed clutch 23 such as an electromagnetic clutch is provided between and. Further, the feed roller clutch 2 is provided between the shaft 20 and the feed roller 4.
4 is arranged and a one-way clutch 25 is provided between the drive gear 13 and the feed roller shaft 20 in order to transmit the drive between the feed roller shaft 20 and the pickup roller 2. Further, between the drive device 40 and the retard roller shaft 30, a drive transmission means similar to the device shown in FIG. 2 is configured. In the example shown in FIG. 3, the coupling 14 is provided between the drive gear 11 supported by the pickup roller shaft 10 and the pickup roller 2, but the drive transmission is performed via the coupling. When replacing the pickup roller,
It is a means provided so that only the roller member of the pickup roller can be easily replaced.

In the sheet feeding device of the present invention configured as described above, as shown in FIG. 4, the leading end of the sheet fed from the sheet separating device 3 is projected into the nip portion of the registration roller device 7 to separate the sheet. The apparatus further feeds the sheet to form a loop Pr on the sheet. Then, the reaction force of the loop of the sheet uniformly presses the leading end of the sheet against the nip portion of the registration roller device to perform the aligning action. Further, in the sheet aligning device of the present invention, the feed roller 4 of the sheet separating device is prevented from rotating in the reverse direction due to the reaction force of the sheet loop, so that the size of the loop formed on the sheet is maintained as it is. It is possible to prevent the sheet from being returned to the sheet feeding device side, and prevent the alignment state of the sheet from being disturbed when the registration roller device is driven to send the sheet toward the image transfer section.

In the paper feeding device shown in FIG. 4, as shown in the graph of FIG. 5, after the paper is fed out from the paper separating device 3, a registration roller device 7 is provided after a predetermined time.
After the leading edge of the sheet is detected by the sensor S arranged at the upstream side of the sheet, the leading edge of the sheet is projected and locked at the nip position of the registration roller device. Further, the loop setting amount R is formed on the paper by driving the feed roller 4 of the paper separating device to perform the additional feeding operation. After that, when the sheet is fed out by the roller device of the sheet separating device according to the feeding instruction, the feeding timing of the leading end portion of the sheet is prevented from deviating. Therefore, as described above, when the reverse rotation preventing member is provided on the feed roller shaft, the feed roller shaft does not rotate excessively, so that it is possible to set the paper feed timing favorably. .

[0019]

Since the sheet feeding device of the image forming apparatus of the present invention is configured as described above, the reverse rotation preventing member is arranged with respect to the feed roller shaft for driving the feed roller, and the sheet feeding device Even if there is play between the gear unit,
Backlash can be prevented from occurring when the feed roller is stopped. Further, in the paper feeding device of the present invention,
By arranging the reverse rotation prevention member directly on the feed roller shaft, even if a force that reverses the feed roller is applied while the feed roller is stopped, the feed roller can be reliably maintained in the stopped state. Is possible. Therefore, even if the reaction force of the loop formed on the thick paper or the like exerts a strong force to reverse the feed roller, the feed roller can be held in a stopped state, and the registration roller device is driven to feed the paper. At this time, it is possible to prevent a deviation in the sheet feeding timing. Further, the sheet feeding device of the present invention is provided only with a reverse rotation preventing member additionally provided on the feed roller shaft, and as the feed roller shaft, for example, a one-way type often used in conventional electrophotographic copying machines and the like. Since a clutch or the like can be used, the structure of the device is not complicated.

[Brief description of drawings]

FIG. 1 is a side view of a sheet feeding device of the present invention.

FIG. 2 is a plan view showing a configuration of a drive system of the paper feeding device of the present invention.

FIG. 3 is a plan view showing another configuration of the drive system of the paper feeding device of the present invention.

FIG. 4 is an explanatory diagram of a paper feeding operation by the paper feeding device of the present invention.

FIG. 5 is a graph showing a sheet conveyance state.

FIG. 6 is an explanatory diagram of a sheet conveying operation in a conventional sheet feeding device.

FIG. 7 is a graph showing a sheet conveyance state in the apparatus of FIG.

[Explanation of symbols]

1 paper feeding device, 2 pickup rollers, 3
Paper sorting device, 4 feed roller, 5 retard roller, 7 registration roller device, 9 paper feed tray, 10 pickup roller shaft, 15
Support link, 20 Feed roller shaft, 21 One-way clutch, 22 Reverse rotation preventing member, 23
Feed clutch, 24 feed roller clutch, 30 retard roller shaft, 31 torque limiter, 40 drive device, 43 drive gear device.

Claims (2)

[Claims] 1. A paper feeding device is configured by combining a pickup roller arranged corresponding to a paper feeding portion of a paper feeding tray and a paper separating device arranged at a downstream portion of the pickup roller, and the paper feeding device is configured downstream of the paper feeding device. A sheet aligning device is configured by arranging a registration roller device in the section, the feed roller of the sheet separating device is driven in the paper feeding direction, and the retard roller is driven in the direction of returning the paper to the tray via the torque limiter. In a device for performing a sorting operation, a loop is formed between the sheet sorting device and the registration roller device to align the sheets, and the sheet is fed by a transport roller device arranged in a sheet transport path at a downstream portion. , A reverse rotation preventing member is arranged on a roller shaft for transmitting drive to the feed roller, and a driving force from a drive device is prevented from rotating reversely. A sheet feeding device for an image forming apparatus, which is provided with a driving unit that transmits through a sheet. 2. A one-way clutch for transmitting the rotation of the feed roller shaft to the feed roller together with the reverse rotation preventing member, and a feed roller clutch for transmitting drive to the pickup roller are arranged on the feed roller shaft. 2. The image forming apparatus according to claim 1, further comprising means for transmitting drive to the feed roller and the pickup roller via a feed roller clutch and a one-way clutch provided on the feed roller shaft. Paper equipment.