JP3327857B2 - Paper feeder and image forming apparatus having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder and an image forming apparatus provided with the same, and more particularly, to the control of rotation of a retard roller of the paper feeder.

[0002]

2. Description of the Related Art Normally, an image forming apparatus cannot form a good image if a recording material, which is a sheet, is conveyed even slightly, so that the recording material is prevented from being fed multiple times. There is a paper feeder that separates and feeds paper one by one.

FIG. 12 shows the configuration of such a paper feeder. In this paper feeder, when performing continuous paper feed, the trailing edge of the recording material conveyed by the paper feed roller 105 is fed. Nip N between roller 105 and retard roller 104
Immediately before exiting, the electromagnetic clutch 113 is turned off at a certain timing to cut off the drive input to the feed roller shaft 105a.

After the drive input is cut in this way, the recording material is pulled out by the pulling roller pair 106 immediately downstream of the paper feeding roller 105 while rotating the paper feeding roller 105 together. In the figure, reference numeral 111 denotes a one-way clutch provided on the paper feed roller shaft 105a to reduce the pulling load of the pull-out roller pair 106, and reference numeral 103 denotes a drive for transmitting the rotation of the paper feed roller shaft 105a to the retard roller shaft 104a. It is an input belt.

Here, such a one-way clutch 1
11 is provided, the feed roller shaft 105a is provided as described above.
When the recording input is cut off and the recording material is pulled out by the pull-out roller pair 106, the drive input portion also follows the retard roller 104 and the torque limiter 102, and the separation mechanism does not work. The next recording paper may be conveyed in an overlapped manner, resulting in double feeding.

Therefore, in order to prevent this, another one-way clutch 112 is inserted so that the retard roller shaft drive input side does not rotate forward (transport direction).

In recent image forming apparatuses, in order to respond to recent demands for higher speed, not only the conveying speed of a recording material is increased, but also a separating unit constituted by a paper feed roller 105 and a retard roller 104. Thus, the interval between the recording materials separated and conveyed one by one (hereinafter, referred to as a paper feeding interval) is reduced. Also,
Even if the sheet is fed in a slightly multi-feed state, some apparatuses have a function of correcting a sheet interval before transferring an image.

[0008]

However, in order to prevent double feeding, the conventional paper feeding device described above waits for the pull-out roller 106 to pull out the preceding recording material without fail. The control for reconnecting the driving of the paper feed roller 105a is performed, and there is a stop time of the paper feed roller 105, so that there is a limit in reducing the paper feed interval.

Further, since the conventional paper feeding device is configured to reliably prevent double feeding, it is possible to feed a predetermined amount of the preceding recording material and the next recording material to be conveyed in an overlapping manner. In addition, when an attempt is made to set the paper feed interval including the overlap amount to a certain value, the paper feed interval is not stabilized, and there is a limit in the control.

Therefore, the present invention has been made in view of such a situation, and it is possible to feed a sheet in a stable state with a small sheet feeding interval including the overlapping amount while allowing double feeding. It is an object of the present invention to provide a paper feeder capable of providing the same and an image forming apparatus having the same.

[0011]

According to the present invention, there is provided a sheet feeding apparatus for separating and conveying sheets stacked on a sheet stacking unit one by one by a sheet feeding roller and a retard roller contacting the sheet feeding roller. Conveying means configured to convey the rear end portion of the preceding sheet and the leading end portion of the next sheet in a state where the trailing end portion of the preceding sheet and the leading end portion of the next sheet abut on the contact portion of the feed roller and the retard roller; and When the overlapping portion approaches the contact portion of the two rollers, the retard roller is caused to rotate together with the paper feed roller to transport the preceding sheet and the next sheet in an overlapping state. Is what you do.

Further, in the invention, it is preferable that the conveying means is provided at a position downstream from the rear end of the sheet by a distance substantially equal to a distance between a contact portion of the two rollers and a front end of the sheet stacked on the sheet stacking means. , And are rollers that are always rotated during paper feeding.

Further, according to the present invention, the conveying means is provided on the sheet stacking means so as to be able to move up and down, and a stacking plate for stacking the sheets, and a urging means for urging the stacking plate to move the sheets to the second position.
Urging means for moving the stacking plate to the vicinity of the abutting portion of the two rollers, the urging means, when the preceding sheet is conveyed by the paper feed roller, the stacking plate, and the next sheet together with the next sheet It is characterized in that the sheet is maintained at an angle at which the sheets are conveyed in an overlapping state.

The present invention also provides a retard roller shaft to which the retard roller is fixed, a rotation drive input unit for inputting a rotation drive of the paper feed roller to the retard roller shaft,
A selection unit provided on the retard roller shaft, for selectively transmitting the rotation drive of the paper feed roller input to the rotation drive input unit to the retard roller shaft, and constantly rotating the paper feed roller. When the overlapping portion of the preceding sheet and the next sheet approaches the abutting portion of the two rollers, transmission of the rotational drive to the retard roller is interrupted by the selecting means, and the retard roller is moved to the sheet feeding roller. It is characterized in that it is made to rotate.

The present invention further includes a pull-out roller provided downstream of the sheet feed roller and the retard roller, for pulling out a sheet held between the sheet feed roller and the retard roller, and pulling the preceding sheet by the pull-out roller. When the sheet is pulled out, the preceding sheet and the next sheet are conveyed in an overlapping state by rotating the retard roller together.

According to another aspect of the present invention, there is provided an image forming apparatus including an image forming section and a paper feeding device, wherein the paper feeding device is as described in any one of the above-mentioned claims 1 to 5. Is what you do.

Further, as in the present invention, the abutting portion of the sheet feeding roller and the retard roller that separates and transports the sheets stacked on the sheet stacking unit one by one, and the rear end of the preceding sheet is connected to the next end by the conveying unit. The sheet is conveyed in a state of being overlapped with the leading edge of the sheet, and when the overlapping portion of the sheet approaches the contact portion of the two rollers, the retard roller is caused to rotate together with the sheet feeding roller, so that the preceding sheet and the next sheet are rotated. The sheets are conveyed in an overlapping state.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an image forming apparatus provided with a sheet feeding device according to a first embodiment of the present invention. In FIG. 1, reference numeral 100 denotes an image forming apparatus, and 101 denotes an image forming apparatus main body. is there.

Here, the image forming apparatus 100 feeds a recording material P on which an image is to be formed from a paper feeding cassette 8 which is a sheet stacking means by a paper feeding device 40, and then passes through a transport path 41. The paper is stacked on the transport belt 46 and transported to the image forming unit 50.

Further, in the image forming apparatus 100, in the image forming section 50, four electrophotographic photosensitive drums 50a, which become four image forming means in response to image information signals transmitted from a reader scanner, a personal computer or the like (not shown). After the toner images formed on the surfaces of 50b, 50c and 50d are sequentially transferred to the recording material P, the fixing device 52
After that, the recording material P on which a monochrome or full-color image is formed is discharged onto the discharge tray 53.

In the same figure, 50e, 50f, 5
0g and 50h are the photosensitive drums 50a, 50b, 50c,
Independently controlled LEDs (light emitting diodes) as light source devices for forming toner images on the surface of 50d
The LEDs 50e, 50f, 50g, and 50h are configured to face the respective surfaces of the photosensitive drums 50a, 50b, 50c, and 50d.

On the other hand, the image forming apparatus 100 has an automatic double-sided function. When an image is formed on both sides of the sheet material P, the recording material P having an image formed on one side is transferred to the main body 101.
After passing through the double-sided pass section 54 provided in the printer, the sheet is conveyed again to the image forming section 50 to form an image on the back surface.

On the other hand, FIG. 2 is a perspective view of a main part of the sheet feeding device 40, in which 4 is a retard roller, 4a is a retard roller shaft, and 5 is a feed roller which constitutes a retard roller separating means together with the retard roller 4. Paper rollers 5a are feed roller shafts.

Reference numeral 3 denotes a roller wound around pulleys 3a and 3b fixed to the retard roller shaft 4a and the paper feed roller shaft 5a, and rotates the paper feed roller shaft 5a rotated in the direction of arrow A by driving means (not shown). This is a drive input belt that is input to the retard roller 4 via the pulleys 3a and 3b. The pulleys 3a and 3b and the drive input belt form a rotation drive input unit.

Further, 2 is provided between the drive input belt 3 and the retard roller 4 of the retard roller shaft 4a,
This is a torque limiter that idles when a rotation torque equal to or more than a predetermined rotation torque is transmitted.

During feeding of the recording material, while the recording material is being conveyed by a predetermined distance by the paper feeding roller 5, the retard roller shaft 4a is driven by the drive input belt 3 via the arrow A of the paper feeding roller 5. Is inputted, the retard roller 4 is rotated in the direction of arrow B.

When the retard roller 4 rotates in the direction of arrow B, that is, in the direction opposite to the direction in which the sheet feeding roller 5 is conveyed, the sheet feeding roller 5 conveys the next sheet and subsequent sheets together with the preceding sheet. Then, the retard roller 4 separates the recording material other than the preceding sheet to be conveyed, and returns the recording material to the upstream direction in the conveying direction.

Thus, as described later, the sheet feeding roller 5
In the case where the next sheet and subsequent sheets reaching the vicinity of the nip N between the sheet and the retard roller 4 have passed through the nip N together with the preceding sheet by the sheet feeding roller 5, the next sheet and the subsequent sheets can be pulled back to the vicinity of the nip. Become.

On the other hand, when the feed roller 5 conveys only the uppermost sheet as the preceding sheet, a rotation torque greater than a predetermined rotation torque is applied to the retard roller 4 via the recording sheet. When a large rotation torque is applied, the retard roller 4 is caused to rotate together with the paper feed roller 5 by the torque limiter 2, whereby only the uppermost sheet is conveyed.

In the present embodiment, during the continuous paper feeding operation, as shown in FIG. 3, the uppermost recording material P1 of the recording materials P stored in the paper feeding cassette 8 is fed to the paper feeding roller. 5, the recording material P2 to be fed next (hereinafter referred to as the next recording material) is always retarded by the feeding roller 5 by the feeding roller 9 constituting the feeding means as shown in FIG. It is transported to the vicinity of the nip N of the roller 4.

Here, assuming that a distance between the leading end of the recording material P stored in the sheet feeding cassette 8 and the nip N is c, the conveying roller 9 is moved from the rear end of the recording material P as shown in FIG. c is provided near the tip. Then, the transport roller 9 is provided at such a position, and the transport roller 9 is continuously rotated, whereby the uppermost recording material (hereinafter, referred to as a preceding recording material) P1 is nipped between the feed roller 5 and the retard roller 4. And the next recording material P2 can be transported to the vicinity of the nip N.

On the other hand, in FIG. 2, reference numeral 1 denotes an electromagnetic clutch which is a selecting means provided between the drive input belt 3 and the retard roller 4, and this electromagnetic clutch 1 is, as shown in FIG. P1 rear end and two rollers 4,
When the distance to the nip N of 5 becomes a, the nip is turned off.

By turning off the electromagnetic clutch 1 in this manner, the driving force is not transmitted to the retard roller 4 so that the retard roller 4 rotates together with the paper feed roller 5 in the direction indicated by the arrow C. Become. Further, when the retard roller 4 rotates in this manner, as described above, the next recording material P2 conveyed to the vicinity of the nip by the pick roller 9 is pulled by the frictional force with the preceding recording material P1, and the preceding recording material P1 is pulled. The sheet P1 is conveyed in an overlapping state.

The electromagnetic clutch 1 is turned on again after the rear end of the preceding recording material P1 has passed through the nip N, whereby the separating operation by the retard roller 4 is restarted, and Even if more than one sheet starts to be conveyed together, the third and subsequent sheets are pulled back to the nip N of the two rollers 4 and 5.

As described above, during the continuous paper feeding operation, the paper feed roller 5 is constantly rotated and the electromagnetic clutch 1 is turned on / off, so that the preceding recording material P1 and the next recording material P2 are conveyed in an overlapped state. I can do it.

The on / off of the electromagnetic clutch 1 is controlled by a control device 30 as shown in FIG. That is, the control device 30 detects the distance between the rear end of the preceding recording material P1 and the nip N between the two rollers 4 and 5 based on a detection signal from the first detection unit 31 that detects that the distance is a. The electromagnetic clutch 1 is turned off. Further, the electromagnetic clutch 1 is turned on based on a detection signal from the second detection means 32 for detecting that the rear end of the preceding recording material P1 has come out of the nip N.

Next, the continuous sheet feeding operation of the sheet feeding apparatus thus configured will be described.

When the continuous feeding operation is started, first, among the recording materials P stored in the paper cassette 8, the uppermost recording material P1 is fed by the feed roller 5 as the preceding recording material P1. Also, when the preceding recording material P1 is fed,
As shown in the figure, the next recording material P2 is conveyed to the vicinity of the nip N between the two rollers 4 and 5.

Here, while the preceding recording material P1 is being conveyed by a predetermined distance, the retard roller 4 is rotating in the direction opposite to the conveying direction of the paper feeding roller 5, so that the paper feeding roller 5 is moved to the next recording material P2. When it is attempted to convey the recording material P1 together with the preceding recording material P1, the retard roller 4 transfers the next recording material P2 to the preceding recording material P1.
And returns to a position near the nip N.

When only the preceding recording material P1 is being conveyed, the retard roller 4 rotates together with the feed roller 5 by the torque limiter 2, so that the feed roller 5
The preceding recording material P1 without being hindered by the retard roller 4
Can be transported.

Next, as shown in FIG. 5, the preceding recording material P1
The distance between the rear end and the nip N between the two rollers 4 and 5 becomes a, and when the first detection means 31 that detects this outputs a detection signal to the control device 30, the control device 30 Then, the electromagnetic clutch 1 is turned off.

When the electromagnetic clutch 1 is turned off as described above, the retard roller 4 starts to rotate together with the paper feed roller 5, whereby the feed roller 5 and the preceding recording material P1 are rotated.
The next recording material P2 conveyed to the vicinity of the nip between the sheet P and the retard roller 4 is conveyed in a state where the next recording material P2 overlaps the preceding recording material P1.

When the trailing end of the preceding recording material P1 comes out of the nip N, a detection signal is input to the control device 30 from the second detecting means 32 which has detected the trailing end of the preceding recording material P1. The control device 30 turns on the electromagnetic clutch 1 according to the signal. As a result, the retard roller 4 resumes rotation, and even if three or more sheets have begun to be conveyed together, the third and subsequent sheets are pulled back to the nip N of the sheet feeding roller 5 by the retard roller 4, which hinders operation. Will not come.

As described above, by continuously rotating the paper feed roller 5 and turning on and off the electromagnetic clutch 1 during the continuous paper feeding operation, the preceding recording material P1 and the next recording material P2 are conveyed in an overlapped state. As a result, it is possible to reduce the sheet feeding interval, and it is possible to respond to recent demands for speeding up.

Further, by changing the on / off timing of the electromagnetic clutch 1, the paper feed interval can be set arbitrarily, and the paper feed interval can be set to be positive or negative without becoming unstable and stable. Continuous feeding is possible. Further, by setting the distance a between the rear end of the preceding recording material P1 and the nip N to 0, a paper feeding interval close to 0 can be obtained, and stable inter-sheet paper feeding can be realized. If the electromagnetic clutch 1 is always turned on, the recording materials can be separated and conveyed one by one.

In the above description, the case where the next recording material P2 is transported to the vicinity of the nip using the transport roller 9 has been described. However, the next recording material P2 may be transported to the vicinity of the nip. If possible, it goes without saying that transport means of another configuration may be used.

For example, as shown in FIG.
Is provided below the nip N between the two rollers 4 and 5, and a loading plate 8a provided to be able to move up and down in the paper feed cassette 8 is pushed up by an urging means 10 to be placed on the loading plate 8a. The recorded recording material may be positioned below the nip.

Further, when the preceding recording material P1 is conveyed by the feed roller 5 on the mounting plate 8a by the urging means 10, the next recording material P2 overlaps with the preceding sheet P1 due to friction of the preceding sheet P1. When the preceding recording material P1 is conveyed, the next recording material P2 is conveyed to the vicinity of the nip as shown in FIG.

Further, in the above description, the rear end of the preceding recording material P1 is detected by the first and second detecting means. However, if it is difficult to detect the rear end, The control device 30 measures the time from the start of the sheet feeding operation, for example, and the rear end of the preceding recording material P1 is
The electromagnetic clutch 1 may be turned off at the timing when the distance to the position a is reached, and the electromagnetic clutch 1 may be turned on at the timing when the rear end of the preceding recording material P1 comes out of the nip N. Good. The on / off timing of the electromagnetic clutch 1 is determined in advance according to the size of the recording material P.

Next, a second embodiment of the present invention will be described.

FIG. 8 is a perspective view of a main part of the sheet feeding apparatus according to the present embodiment. 2, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In the figure, reference numeral 15 denotes a paper feed roller, and 16 denotes a pull-out roller located immediately downstream of the paper feed roller 15. Here, as shown in FIG. 9, the paper feed roller 15 is a roller collar 17 having a one-way clutch 11 built therein.
When the feed roller driving shaft 15a is stopped, the roller runs idle when a force acts in the pulling direction from the pulling roller side.

In FIG. 8, reference numeral 13 denotes an electromagnetic clutch provided on the paper feed roller shaft 15a. As shown in FIG.
The switch is turned off when the distance between the rear end of the roller 1 and the nip N between the two rollers 4 and 15 becomes b.

By turning off the electromagnetic clutch 13 in this manner, the driving force is not transmitted to the paper feed roller 15, and in this state, when the pull-out roller 16 pulls out the recording material P, the paper feed roller 15 While rotating in the direction of arrow A, the retard roller 4 comes to rotate with the sheet feeding roller 15 in the direction indicated by arrow C. Further, when the retard roller 4 rotates in this way, the first
As in the embodiment, the next recording material P2 conveyed to the vicinity of the nip by the pick roller 9 is pulled by the frictional force with the preceding recording material P1, and is conveyed in a state of overlapping with the preceding recording material P1. .

The electromagnetic clutch 13 is turned on again after the rear end of the preceding recording material P1 has passed through the nip N, whereby the separating operation by the retard roller 4 is restarted, and Even when more than one sheet starts to be conveyed together, the third and subsequent sheets are pulled back to the nip N of the sheet feeding roller 15.

As described above, when the recording material is pulled out by the pull-out roller 16 during the continuous paper feeding operation, the electromagnetic clutch 13 is pulled out.
Are turned on and off, so that the preceding recording material P1 and the next recording material P2 can be conveyed in an overlapping state.

Next, the continuous sheet feeding operation of the sheet feeding device having such a configuration will be described with reference to FIGS.

When the feeding operation is started, first, among the recording materials P stored in the sheet cassette 8 as shown in FIG.
The uppermost recording material P1 is fed by the feed roller 15 as the preceding recording material P1. Further, when the preceding recording material P1 is fed, as shown in the figure, the next recording material P2 is transported by the feeding means shown in the first embodiment to the feeding roller 15 and the retard roller 4 as shown in FIG. It is transported to the vicinity of the nip N.

Here, while the preceding recording material P1 is being conveyed by a certain distance, the retard roller 4 is rotating in the direction B opposite to the rotation direction A of the sheet feeding roller 15, so that the sheet feeding roller 1
5 tries to convey the next recording material P2 together with the preceding recording material P1, the retard roller 4 separates the next recording material P2,
Return to the position near nip N.

When only the preceding recording material P1 is being conveyed, the retard roller 4 rotates together with the paper feed roller 15 by the torque limiter 2.
Can transport the preceding recording material P1 without being hindered by the retard roller 4.

Next, as shown in FIG.
When the distance between the rear end of the roller 1 and the nip N between the two rollers 4 and 15 becomes b, the control device 30 turns off the electromagnetic clutch 13 and cuts off the drive input to the paper feed roller shaft 15a. . Then, in this state, the preceding recording material P1 is pulled out by the pulling-out roller 16 so that the sheet feeding roller 1 is pulled out.
Reference numeral 5 idles in the direction of arrow A due to the preceding recording material P1 being pulled out.

Further, when the paper feed roller 15 idles, the retard roller 4 starts to rotate along with the paper feed roller 15 and rotates in the direction of arrow C, whereby the two rollers 4 and 15 are moved together with the preceding recording material P1. Is conveyed in a state where the next recording material P2 conveyed to the vicinity of the nip overlaps with the preceding recording material P1.

When the trailing end of the preceding recording material P1 comes off the nip N, the control device 30 sets the electromagnetic clutch 1
Turn 3 on. As a result, even if the feed roller 15 and the retard roller 4 resume rotation and three or more sheets are conveyed together, the third and subsequent sheets are moved by the retard roller 4 to the nip N between the two rollers 4 and 15. It is pulled back and does not disturb the operation.

As described above, when the recording material is pulled out by the pull-out roller 16 during the continuous paper feeding operation, the electromagnetic clutch 13
By turning on and off, it is possible to convey the preceding recording material P1 and the next recording material P2 in an overlapping state, thereby making it possible to reduce the paper feeding interval, and to respond to the recent demand for higher speed. Can be.

Further, by changing the on / off timing of the electromagnetic clutch 13, the paper feed interval can be set arbitrarily, and the paper feed interval can be set to a positive or negative value without becoming unstable and stable. Continuous feeding is possible. Further, the rear end of the preceding recording material P1 and the nip N
By setting the distance b to 0 to 0, it is possible to obtain a paper feed interval close to 0, and to realize stable inter-sheet feed.

[0067]

As described above, according to the present invention, a sheet conveyed in a state of being superposed on a contact portion between a feed roller and a retard roller rotates the retard roller with the feed roller at a predetermined timing. By doing so, the sheets can be conveyed in an overlapped state, so that the sheets can be fed in a stable state with a small sheet feeding interval including the overlap amount while allowing the double feeding. Further, by controlling the timing of the rotation of the retard roller, the amount of overlap between the preceding recording material and the next recording material can be set to a predetermined value, and stable continuous paper feeding can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the paper feeding device.

FIG. 3 is a diagram illustrating a state during continuous paper feeding operation of the paper feeding device.

FIG. 4 is a perspective view illustrating a conveying unit of the sheet feeding apparatus that conveys the rear end portion of the preceding sheet and the front end portion of the next sheet in an overlapping state.

FIG. 5 is a diagram illustrating a continuous paper feeding operation of the paper feeding device.

FIG. 6 is a control block diagram of the paper feeding device.

FIG. 7 is a view for explaining another conveying means of the sheet feeding device for conveying a rear end portion of a preceding sheet and a front end portion of a next sheet in an overlapped state.

FIG. 8 is a perspective view of a main part of a sheet feeding device according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating a one-way mechanism in a sheet feeding roller of the sheet feeding device.

FIG. 10 is a diagram illustrating a continuous paper feeding operation of the paper feeding device.

FIG. 11 is a diagram illustrating a continuous sheet feeding operation of the sheet feeding device.

FIG. 12 is a perspective view of a main part of a conventional sheet feeding device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electromagnetic clutch 2 torque limiter 3 drive input belt 4 retard roller 4 a retard roller shaft 5, 15 feed roller 8 paper feed cassette 8 a mounting plate 9 pick roller 10 biasing means 11 built-in one-way clutch 16 pull-out roller 30 control device 40 feed Paper device 50 Image forming unit 100 Image forming device P1 Prior recording material P2 Secondary recording material

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 3/52

Claims (6)

(57) [Claims] 1. A sheet loaded on a sheet loading means,
In a sheet feeding apparatus that separates and conveys one sheet at a time by a sheet feeding roller and a retard roller that abuts on the sheet feeding roller, a rear end portion of the preceding sheet and a next sheet A conveying unit configured to convey the sheet in a state in which the leading end portion is overlapped, and when the overlapping portion of the preceding sheet and the next sheet approaches the contact portion of the two rollers, the retard roller feeds the sheet. A sheet feeding device characterized in that the preceding sheet and the next sheet are conveyed in an overlapping state while being rotated together with a roller. 2. The method according to claim 1, wherein the conveying unit is located downstream from a rear end of the sheet by a distance substantially equal to a distance between a contact portion of the two rollers and a front end of a sheet stacked on the sheet stacking unit. 2. The paper feeding device according to claim 1, wherein the paper feeding device is a roller that always rotates during paper feeding. 3. A loading plate provided on the sheet loading means so as to be able to move up and down, and a loading plate for loading the sheets,
Urging means for urging the stacking plate to move the sheet to a position near the contact portion of the two rollers, the urging means moving the stacking plate by the paper feed roller to the preceding sheet. 2. The sheet feeding device according to claim 1, wherein when the sheet is conveyed, the sheet is kept at an angle at which the next sheet and the preceding sheet are conveyed in an overlapping state. 4. A retard roller shaft to which the retard roller is fixed, a rotation drive input unit for inputting a rotation drive of the sheet feeding roller to the retard roller shaft, and a rotation drive input provided on the retard roller shaft. Selection means for selectively transmitting the rotation drive of the sheet feed roller input to the section to the retard roller shaft, while always rotating the sheet feed roller, and the overlapping portion of the preceding sheet and the next sheet is When approaching the abutting portion of the two rollers, transmission of the rotation drive to the retard roller is interrupted by the selection means, and the retard roller is caused to rotate together with the paper feed roller. The paper feeding device according to claim 1. 5. A pull-out roller provided downstream of the feed roller and the retard roller, for pulling out a sheet sandwiched between the feed roller and the retard roller, wherein the pull-out roller pulls out the preceding sheet. By rotating the retard roller,
2. The sheet feeding device according to claim 1, wherein the preceding sheet and the next sheet are conveyed in an overlapping state. 6. An image forming apparatus comprising an image forming unit and a paper feeding device, wherein the paper feeding device is the one according to any one of claims 1 to 5. apparatus.