JP2005075490A - Paper feeder and image forming apparatus including it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder, allowing a user to find a paper jam and inhibit feeding of the next paper sheet, and an image forming apparatus having the paper feeder. <P>SOLUTION: This paper feeder has a feed roller 3 and an abutting reverse roller 4, and the feeder is connected to a driving motor through a feed clutch 21 for transmitting or interrupting the power from the driving motor to the feed roller 3. In the paper feeder, after the trailing end of a paper sheet passes through a nip between the feed roller 3 and the reverse roller 4 driven to rotate by the driving motor, the feed clutch 21 is turned off to interrupt the transmission of power to the feed roller 3 so that the feed roller 3 is put in the freely rotating state, the rotation of a reverse shaft 5 is transmitted to the reverse roller 4 through a torque limiter 6, and the reverse roller 4 is driven to rotate in the counter-paper feeding direction to return another paper sheet nipped between the reverse roller 4 and the feed roller 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet feeding device that feeds sheets one by one and an image forming apparatus having the sheet feeding device.

In a copying machine, a printer, a facsimile, a multifunction machine of these, an image scanner, or the like, a paper feeding device that feeds paper such as recording paper or a document one by one is widely used (for example, see Patent Documents 1 and 2). ).
Japanese Patent Laid-Open No. 10-218403 (pages 2 to 3, FIG. 3) Japanese Patent Laid-Open No. 9-183529 (pages 4 to 5, FIG. 1)

FIG. 10 is a schematic view showing a conventional example of a paper feeding device for feeding paper one by one. In this paper feeding device, the paper P is sent out in the direction of the arrow AC when the pickup roller 2C contacting the uppermost paper of the paper P loaded on the paper feeding tray 1C rotates.
A feed roller 3C and a reverse roller 4C in contact with the feed roller 3C are disposed downstream of the pickup roller 2C in the sheet conveying direction. The feed roller 3C is also illustrated in FIG. It is connected to a drive motor not shown.
The reverse roller 4C is coupled to a reverse shaft 5C that is rotationally driven by a drive motor via a torque limiter (not shown). Here, the rotation direction when each of the rollers 2C, 3C, and 4C rotates in the direction of transporting the paper P in a predetermined feeding direction is defined as a paper feeding direction.
If the rotational direction opposite to the paper feeding direction is referred to as the counter paper feeding direction, the feed roller 3C rotated in the paper feeding direction (arrow BC direction) by the drive motor and the reverse roller 4C are fed. When only one sheet P1 to be fed is fed, the reverse roller 4C is rotated in the sheet feeding direction (arrow CC direction) in conjunction with the movement of the sheet P1 by the action of the torque limiter.
Further, when the paper P1 to be fed between the feed roller 3C and the reverse roller 4C and the other paper P2 are fed together, the reverse shaft 5C rotates to the reverse roller 4C via the torque limiter. Then, the reverse roller 4C rotates in the reverse paper feeding direction indicated by the arrow IC, and the other paper P2 that contacts the reverse roller 4C is returned in the arrow DC direction.

FIG. 11 is a schematic view showing a sheet fed between the feed roller and the reverse roller. As described above, this type of paper feeding device that can prevent a plurality of papers from being fed simultaneously is generally referred to as an FRR type paper feeding device.
In the conventional paper feeding device of this system, after the last paper in a series of paper feeding operations is sent out, the next paper P2 is fed between the feed roller 3C and the reverse roller 4C as shown in FIG. Stop while holding in between.
In this state, when the paper feed tray 1C is pulled out, for example, in a direction perpendicular to the paper surface of FIG. 11, the paper P2 is left sandwiched between the feed roller 3C and the reverse roller 4C. When 1C is set, a large external force is applied to the paper P2, and the paper may be jammed.
In view of this, various types of paper feeding apparatuses that eliminate the above-described drawbacks have been proposed (see, for example, Patent Documents 1 and 2). According to the paper feeding device according to this proposal, it is possible to avoid a problem in which, after the last paper is sent out, the next paper remains stopped in a state of being sandwiched between the feed roller and the reverse roller. .
However, the configuration of the apparatus is complicated, the number of parts increases, and the cost increases. For example, according to the paper feeding device described in Patent Document 1, a reverse clutch for transmitting or interrupting power from the reverse shaft to the reverse roller is required, which increases the cost of the entire device.
Further, when a paper jam occurs in any place of the image forming apparatus, the conventional image forming apparatus needs to stop the drive motor, display the paper jam to the user, and have the user perform the paper jam processing.
However, when a sheet on the manual feed tray is slightly fed in a manual sheet feeder, it is difficult for the user to determine whether or not the sheet should be removed, and the user is confused without noticing that the sheet is jammed paper. In recent years, the structure of the device itself, particularly the paper transport path, has become complicated, and there are a variety of paper jam handling, so the user cannot find a paper jam and tends to perform operations such as turning off the power of the entire device. .
Once the power is turned off, if the paper fed from the manual feed tray is stopped without being detected by a sensor or the like, the next paper is fed as it is.
This is a factor that causes further paper jams. In order to solve this problem, there is a method of providing a sheet detection unit such as a sensor immediately after the manual sheet feeding unit, which causes an increase in cost.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a paper feeding device that allows a user to find a jammed paper and prevent feeding of the next paper and an image forming apparatus having the paper feeding device in order to solve the above-described problems. There is to do.

In order to solve the above-described problems, in the invention described in claim 1, a pickup roller that feeds stacked sheets, a feed roller that is disposed downstream of the pickup roller in the sheet conveyance direction, and a contact with the feed roller. A reverse roller in contact with the feed motor, wherein the feed roller is connected to the drive motor via a feed clutch that transmits or cuts power from the drive motor to the feed roller. After the end passes through the nip between the feed roller and the reverse roller that are rotationally driven by the drive motor, the feed clutch is turned off, the transmission of power from the drive motor to the feed roller is interrupted, The feed roller was allowed to rotate freely and was rotated by the drive motor. The rotation of the berth shaft is transmitted to the reverse roller via a torque limiter, and the reverse roller is driven to rotate in the reverse sheet feeding direction so as to return another sheet sandwiched between the reverse roller and the feed roller. The constructed paper feeder is the main feature.
According to a second aspect of the present invention, at the start of paper feeding, prior to feeding out the paper by the pickup roller, the drive motor rotates the reverse shaft, turns off the feed clutch, and feeds the feed motor from the feed motor. The paper feeding device according to claim 1, wherein transmission of power to the roller is cut off so that the feed roller can freely rotate.

According to a third aspect of the present invention, there is provided a pair of registration rollers disposed downstream of the feed roller and the reverse roller in the sheet conveyance direction, the leading end of the sheet is abutted against the stopped pair of registration rollers, and the sheet is slackened. The paper is temporarily stopped after forming, and the pair of registration rollers is rotated at a predetermined timing to feed the paper, and the drive motor is stopped while the feed clutch is on, The paper feeding device according to claim 1 or 2, wherein conveyance of the paper is temporarily stopped.
According to a fourth aspect of the present invention, the paper feeding device is the paper feeding device according to any one of the first to third aspects, comprising a plurality of the paper feeding devices, and as drive motors for the plurality of paper feeding devices, An image forming apparatus using one common drive motor is the main feature.
According to a fifth aspect of the present invention, the paper feeding device according to the first aspect is used, and the driving motor in the paper feeding device is driven for a predetermined time at the time of restart after the device is temporarily stopped due to paper jam. The main feature is an image forming apparatus that stops.
According to a sixth aspect of the invention, an image forming apparatus using the paper feeding device according to the first aspect and driving a drive motor in the paper feeding device for a predetermined time when the apparatus power is turned on is the main feature.

According to the first aspect, when the paper feeding operation is stopped immediately due to a paper jam or the like, the feed roller and the reverse roller nip portion do not cause the user to determine whether the last fed paper is a paper jam. Even when the user finishes the jamming process with the paper fed, the feed roller can be reversed for a predetermined time before the paper feed is resumed to return the paper to the original paper feed position.
Even if the user does not know the position of the paper when the paper is jammed and turns off the apparatus power, the paper can be returned to the original paper feeding position in the same way as described above. It is possible to provide a good paper feeding device that does not.
According to the second aspect, even when the user does not know the position of the paper when the paper is jammed and the apparatus power is turned off, the paper can be returned to the original paper feeding position in the same manner as described above. Furthermore, it is possible to provide a good paper feeding device that does not waste paper.
According to the third aspect, even when the user does not know the position of the paper at the time of paper jam and the apparatus power is turned off, the paper can be returned to the original paper feeding position in the same manner as described above. Furthermore, it is possible to provide a good paper feeding device that does not waste paper.
According to the fourth aspect, even when the user does not know the position of the paper when the paper is jammed and the apparatus power is turned off, the paper can be returned to the original paper feeding position as described above. Furthermore, it is possible to provide a good image forming apparatus that does not waste paper.
According to the fifth aspect, even when the user does not know the position of the paper at the time of paper jam and the apparatus power is turned off, the paper can be returned to the original paper feeding position in the same manner as described above. Furthermore, it is possible to provide a good image forming apparatus that does not waste paper.
According to the sixth aspect, even when the user does not know the position of the paper when the paper is jammed and the apparatus power is turned off, the paper can be returned to the original paper feeding position as described above. Furthermore, it is possible to provide a good image forming apparatus that does not waste paper.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus provided with a sheet feeding device. The image forming apparatus shown here has four drum-shaped photoconductors 8Y, 8M, 8C, and 8BK arranged in the main body 7, and a charging unit, an exposure unit, and a developing unit attached to each photoconductor. In cooperation with each other, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are formed.
Further, the image forming apparatus is provided with first to third paper feeding devices 9, 9A, 9B, and a sheet fed from any one of the paper feeding devices is arranged to face the photoreceptors 8Y to 8BK. Then, the toner image of each color is superimposed and transferred from each of the photoreceptors 8Y to 8BK onto the sheet.
The sheet on which the toner image has been transferred passes through the fixing device 11, and at this time, the toner image is fixed on the sheet by the action of heat and pressure. The paper that has passed through the fixing device 11 is discharged onto a paper discharge tray 12.
The first paper feeding device 9 is configured as a manual paper feeding device that feeds the paper P manually set on the paper feeding tray 1 by the user, and the second and third paper feeding devices 9A and 9B are configured as follows. The paper P stacked on the paper feed trays 1A and 1B is fed.
Any of the paper feeding devices 9, 9A, 9B picks up rollers 2, 2A, 2B for feeding the stacked paper P, and a feed roller 3, which is arranged downstream of the pick-up rollers 2, 2A, 2B in the paper transport direction, 3A, 3B, and reverse rollers 4, 4A, 4B which are in contact with the feed rollers 3, 3A, 3B and abut against these rollers 3, 3A, 3B, respectively.
As a common element, a registration roller pair 13 is disposed on the downstream side in the sheet conveyance direction with respect to the feed roller 3 and the reverse roller 4. The paper P sent out from each of the paper feed trays 1, 1 </ b> A, 1 </ b> B hits the registration roller pair 13 and temporarily stops.
Thereafter, when the registration roller pair 13 starts rotating at a predetermined timing, the toner image on each of the photoconductors 8Y to 8BK is fed between the photoconductor and the transfer belt 10 at a timing at which the toner image is correctly transferred onto the paper. Is done.
Since the pickup rollers 2, 2A, 2B, feed rollers 3, 3A, 3B, reverse rollers 4, 4A, 4B and the related components of each of the paper feeding devices 9, 9A, 9B are substantially the same, the first Only the rollers 2, 3, 4 in the sheet feeding device 9 and the configuration related thereto will be described.

FIG. 2 is a schematic perspective view illustrating a roller and a configuration related to the roller in the first paper feeding device. As shown in FIG. 2, the feed roller 3 is supported on the feed shaft 14 via the one-way clutch 15 or is fixed to the feed shaft 14.
The shaft portion of the pickup roller 2 is supported so as to be swingable in the direction of arrow E with respect to the feed shaft 14, and is drivingly connected to the feed roller 3 via the timing belt 16, and is synchronized with the feed roller 3. Is rotated. The reverse roller 4 is connected to the reverse shaft 5 via a torque limiter 6.
A drive gear 17 that is rotationally driven by a drive motor (not shown) meshes with a reverse gear 18 that is fixed to the reverse shaft 5. The reverse gear 18 is drivingly connected to a feed gear 20 rotatably supported by the feed shaft 14 via an intermediate gear 19, and a feed clutch 21 made of, for example, an electromagnetic clutch is provided at the other end of the feed shaft 14. It has been.
The rotation of the drive motor is transmitted to the reverse shaft 5 via the drive gear 17 and the reverse gear 18, and the rotation of the reverse gear 18 is transmitted to the feed gear 20 via the intermediate gear 19.
When the feed clutch 21 is on, the rotation of the feed gear 20 is transmitted to the feed shaft 14 via the feed clutch 21, and the feed roller 3 and the pickup roller 2 are fed in the feed directions indicated by arrows B and F, respectively. However, when the feed clutch 21 is turned off, the rotation of the feed gear 20 is not transmitted to the feed shaft 14.
Thus, the feed roller 3 is connected to the drive motor via the feed clutch 21 that transmits or cuts the power from the drive motor to the feed roller 3, and the reverse roller 4 is connected to the reverse shaft 5 that is rotationally driven by the drive motor. They are connected via a torque limiter 6. As the drive motor, it is preferable to use a stepping motor capable of performing on / off control with high accuracy.

FIG. 3 is a schematic diagram showing the first paper feeding device and the registration roller pair. FIG. 4 is a timing chart for explaining the sheet feeding timing. In the timing chart shown in FIG. 4, the drive motor first starts to operate in response to the paper feed start signal, and its rotation is transmitted to the reverse shaft 5 via the drive gear 17 and the reverse gear 18. 2 is driven to rotate in the direction indicated by the arrow G.
At this time, the pickup roller 2 is separated from the paper P on the paper feed tray 1 as shown in FIG. 3, and the feed clutch 21 is turned off, so that power is transmitted from the drive motor to the feed roller 3. Blocked. Therefore, the feed roller 3 is in a state where it can freely rotate together with the feed shaft 14.
For this reason, the rotation of the reverse shaft 5 that is rotationally driven by the drive motor in the direction of arrow G is transmitted to the reverse roller 4 via the torque limiter 6, and the reverse roller 4 is the reverse of the reverse roller 4 indicated by the arrow I in FIGS. Rotates in the paper feed direction. At this time, the feed roller 3 is rotated in the reverse sheet feeding direction indicated by the arrow J by the reverse roller 4.

FIG. 5 is a schematic view showing the first paper feeding device and the registration roller pair in which the pickup roller is lowered. When a predetermined time T1 has elapsed from the start of rotation of the drive motor, the feed clutch 21 is turned on, and the pickup roller 2 descends and presses against the paper P as shown in FIG.
Thereby, the rotation of the drive motor is transmitted to the feed roller 3 and the pickup roller 2, and these rollers 2 and 3 rotate in the paper feeding direction indicated by arrows B and F in FIG. The one-way clutch 15 transmits the rotation of the feed shaft 14 in this direction to the feed roller 3.
As a result, the paper P on the paper feed tray 1 is fed in the direction of arrow A, and this paper P is sandwiched between the feed roller 3 and the reverse roller 4 and conveyed. Thus, the feed roller 3 and the reverse roller 4 are rotationally driven in the paper feeding direction (arrow B direction) by the drive motor.
When only one sheet P1 to be fed is fed between the feed roller 3 and the reverse roller 4, the reverse roller 4 is operated by the torque limiter 6 to move the arrow in conjunction with the movement of the sheet P1. The paper is rotated in the paper feeding direction indicated by C.
Further, a sheet P1 to be fed and other sheets (shown by broken lines in FIG. 5) P2 are fed together between the feed roller 3 and the reverse roller 4 that are rotationally driven by the drive motor.
At that time, the rotation of the reverse shaft 5 driven to rotate by the drive motor is transmitted to the reverse roller 4 through the torque limiter 6, and the reverse roller 4 rotates in the counter-feeding direction indicated by the arrow I in FIG. The other sheet P2 in contact with the reverse roller 4 is returned in the direction of arrow D.
After the paper fed out from the paper feed tray 1 is inserted into the feed roller 3 and the reverse roller 4, the pickup roller 2 may be separated from the paper on the paper feed tray 1 or brought into contact with the paper. You can leave it alone.

FIG. 6 is a schematic diagram showing a first paper feeding device and a registration roller pair in which a sheet has slack in contact with the registration roller pair. As described above, when the paper P1 to be fed is transported for a time T2 as shown in FIG. 4, the leading edge thereof is detected by the registration sensor 22 shown in FIG.
Next, the leading edge of the sheet hits the stopped pair of registration rollers 13, and a slack as shown in FIG. 6 is formed on the sheet P1, and the leading edge of the sheet P1 is corrected. After the registration sensor 22 detects the leading edge of the sheet, the drive motor stops after a predetermined time T3 has elapsed, the drive to the feed roller 3 is cut off, and the sheet P1 stands by with a slack formed. At this time, the feed clutch 21 maintains the on state.
Next, the registration roller pair 13 starts rotating at a timing at which the toner image can be correctly transferred from each of the photoreceptors 8Y to 8BK (FIG. 1) to the paper P1, and the drive motor resumes its operation to feed the feed roller 3. Are driven to rotate in the paper feeding direction.
As described above, the leading end of the sheet P1 is abutted against the stopped pair of registration rollers 13 to form a slack on the sheet P1, and then the sheet is temporarily stopped. The pair of registration rollers 13 is rotated at a predetermined timing, and the sheet Feed P1.
However, at that time, the drive motor is stopped while the feed clutch 21 is turned on, and the conveyance of the paper P1 is temporarily stopped. Therefore, it is possible to prevent a problem that the paper roller P1 is not slackened due to the reverse rotation of the feed roller 3.
That is, if the drive motor is stopped with the feed clutch 21 turned off, the reverse roller 4 rotates in the counter-feeding direction (the direction of the chain arrow I in FIG. 6) due to the external force received from the stopped paper P1. The rotation is transmitted to the feed roller 3, and the feed roller 3 may rotate in the counter-feeding direction (the direction of the dashed line arrow J in FIG. 6), and the sagging of the paper P1 may be eliminated.
Further, when the feed clutch 21 is turned off while the drive motor is operated to form a sag in the paper P1, the reverse roller 4 rotates in the anti-paper feeding direction due to the rotation of the drive motor and the sag in the paper P1 is eliminated. There is a fear.
On the other hand, in the paper feeder of the present embodiment, the drive motor is stopped while the feed clutch 21 is turned on, so the feed roller 3 tries to rotate with the reverse roller 4.
However, since the drive motor and the feed roller 3 are in a directly connected state, the feed roller 3 is not rotated in the anti-feed direction by the hold torque of the drive motor, and there is no possibility that the slack of the paper P1 is eliminated.

FIG. 7 is a schematic diagram showing the first sheet feeding device and the registration roller pair in which the leading edge of the sheet passes through the registration roller pair. The sheet P1 is further transported by the operation of the drive motor again.
However, as shown in FIG. 7, the rear end of the sheet P1 to be fed passes through the nip between the feed roller 3 and the reverse roller 4 that are rotationally driven by the drive motor, that is, as shown in FIG. When the elapsed time T4 has elapsed, the feed clutch 21 is turned off.
At this time, in the example shown in FIG. 7, the sheet P <b> 1 is separated from the nip between the rollers 3 and 4 by a distance X. By turning off the feed clutch 21 in this state, the transmission of power from the drive motor to the feed roller 3 is cut off, and the feed roller 3 can freely rotate.
On the other hand, the drive motor continues to operate at this time, and therefore, the rotation of the reverse shaft 5 driven to rotate by the drive motor is transmitted to the reverse roller 4 via the torque limiter 6.
As a result, the reverse roller 4 is rotationally driven in the reverse paper feeding direction indicated by the arrow I in FIG. 7, and the feed roller 3 rotates along with the feed shaft 14 in the reverse paper feeding direction indicated by the arrow J.
As a result, as shown by a broken line in FIG. 7, when another sheet P2 is sandwiched between the reverse roller 4 and the feed roller 3, the sheet P2 is returned in the direction of the arrow D, and both rollers 3, 4 away from the nip. When the sheets are continuously fed, this operation is performed every time the sheets are fed.
When the last sheet of the series of sheet feeding operations has been fed, as shown in FIG. 4, after the feed clutch 21 is turned off, the drive motor is operated for a time T5 to return the other sheet P2. And the operation of the drive motor is stopped when the other paper P2 is separated from the nip between the rollers 3 and 4. When the sheet is continuously fed, the drive motor can be kept operating.
As described above, since the paper P2 that should not be fed can be fed back from the nip between the feed roller 3 and the reverse roller 4 each time, when the paper feeding operation is finished, There is no problem that the next sheet stops in a state where it is held between the feed roller 3 and the reverse roller 4.
For this reason, it is possible to eliminate the possibility of jamming of paper even when the paper feed tray is removed from the image forming apparatus main body and mounted again. Moreover, unlike the conventional paper feeder, there is no need to provide a reverse clutch, and an increase in the number of parts of the paper feeder and an increase in its cost can be suppressed.

Further, in the conventional paper feeding device, after the paper to be fed is inserted into a roller pair (hereinafter referred to as a grip roller pair) positioned downstream of the feed roller and the reverse roller, The feed clutch is turned off in a state where the roller is sandwiched between the feed roller and the reverse roller, and thereafter, the sheet is conveyed while being pulled by the grip roller pair on the downstream side.
According to this configuration, the feed roller conveys the sheet before the feed clutch is turned off. However, when the feed clutch is turned off, the feed roller does not exert a conveying force on the sheet. For this reason, the load applied to the pair of grip rollers changes abruptly from the time when the feed clutch is turned off, resulting in uneven rotation of the drive motor that drives the load.
Therefore, for example, when the photoconductor is also driven by the drive motor, an impact is applied to the photoconductor, which may cause image unevenness.
Also, in a device in which no grip roller pair is arranged between the feed roller and reverse roller and the registration roller pair, the feed roller and reverse roller side pulls the paper, so the paper conveyance speed of the registration roller pair changes. As a result, the image may be deformed from the middle of the paper.
On the other hand, in the paper feeding device according to the present embodiment, the feed clutch 21 is turned off after the trailing edge of the paper passes between the feed roller 3 and the reverse roller 4, so that the above-described conventional drawbacks occur. Therefore, it is possible to always form a high quality image.
Further, as described above, at the start of paper feeding, prior to feeding the paper by the pickup roller 2, the reverse shaft 5 is rotationally driven by the drive motor for the time T1 shown in FIG.
At the same time, the feed clutch 21 is turned off, the transmission of power from the drive motor to the feed roller 3 is cut off, and the feed roller 3 can be freely rotated. In the case of a manual sheet feeding device such as the paper device 9, it is possible to prevent the occurrence of a jam due to an inappropriate setting of paper.

Next, FIG. 8 is a schematic view showing a case where a plurality of sheets are pushed between the feed roller and the reverse roller.
That is, as shown in FIG. 8, when the user sets the paper P on the paper feed tray, if the paper P is strongly pressed and a plurality of papers are pushed between the feed roller 3 and the reverse roller 4, In the case of the conventional paper feeding device, there is a risk of jamming when the paper is sent out.
In order to prevent the occurrence of such a problem, when a large number of sheets are pushed between the rollers 3 and 4 as shown in FIG. 8, this is detected by a sensor and notified to the user by a buzzer or a lamp, A method for urging the user to reset paper has been proposed. However, according to such a configuration, the cost of the paper feeding device increases.
On the other hand, according to the paper feeding device of the present embodiment, the reverse shaft 5 is driven to rotate and the feed roller 3 can be freely rotated before the paper is fed out. It rotates in the paper direction (the direction of arrow I in FIG. 8).
The feed roller 3 is rotated in the arrow J direction, and the paper pushed between the rollers 3 and 4 can be returned in the arrow D direction. In this way, it is possible to automatically reset the paper to an appropriate state, and to prevent the paper from jamming.
The image forming apparatus shown in FIG. 1 is provided with a plurality of paper feeding devices 9, 9A, 9B. If a common motor is used as a drive motor for the plurality of paper feeding devices, The overall cost can be reduced.
At that time, the rotation of the drive motor is also transmitted to the sheet feeding device that is not used, and at this time, the feed clutch of the sheet feeding device remains off. Rotate to.
At this time, since the feed roller can rotate in the counter paper feeding direction without load, the reverse roller rotates in the counter paper feeding direction without generating torque in the torque limiter. Less. In addition, since torque is not generated in the torque limiter, it is possible to prevent a decrease in its life.

FIG. 9 is a flowchart for explaining the operation of the apparatus according to the present invention, which is arranged as a part of the image forming apparatus and mounted in the manual feed section, when a paper jam occurs and the apparatus is turned on.
The sheet conveyed from the manual sheet feeding unit 9 passes through the registration roller 13, is imaged by the image forming apparatus, passes through the fixing unit, and is discharged to the sheet discharge tray 12. When continuous paper is passed through the process, for example, when a paper jam occurs in the fixing unit 11 (S1), the drive motor is stopped so that the subsequent paper does not collide with the jammed paper.
Next, it is determined whether or not there is a sheet on the manual sheet feeder 9 (S2). If there is a sheet, it is determined whether or not there is a sheet on the sensor 22 (S3), and there is a sheet on the sensor 22. Then, a paper jam is displayed on the display unit or the like in this state.
At the same time, the user is instructed to handle the jammed paper. However, since it is difficult for the user to determine whether or not to remove a slightly fed sheet from a sheet feeding device such as manual feeding, it is usually left as it is.
Therefore, when the jammed paper such as the fixing unit is removed, the apparatus control unit confirms that there is no paper in the sensor 22 (pre-registration sensor), and feeds the paper feeding motor from the sensor 22 to the manual feed roller / reverse roller. Rotate more than the distance to the nip (S5).
Similarly, when the power is turned on (S1), it is assumed that the user has turned off the power when the paper is jammed, and this apparatus control unit confirms that there is no paper in the sensor 22 (pre-registration sensor), and then The paper motor is rotated more than the distance from the sensor 22 to the manual feed roller / reverse roller nip.
The sheet is returned to just before the feed roller / reverse roller nip by the rotating operation. As a result, the paper start position at the time of restarting is optimized, and there is no paper jam.

According to the present invention, the paper feed device 9 feeds the stacked paper, the pickup roller 2 that feeds the stacked paper, the feed roller 3 disposed downstream of the pickup roller 2 in the paper transport direction, and the reverse that contacts the feed roller 3. And a roller 4.
The feed roller 3 is connected to a drive motor through a feed clutch 21 that transmits or cuts power from a drive motor (not shown) to the feed roller 3, and the reverse roller 4 is reversely driven by the drive motor. The shaft 5 is connected via a torque limiter 6.
When only one sheet to be fed is fed between the feed roller 3 rotated in the sheet feeding direction by the drive motor and the reverse roller 4, the reverse roller 4 is operated by the action of the torque limiter 6. The paper moves in the paper feeding direction in conjunction with the movement of the paper.
When a sheet to be fed and other sheets are fed together between the feed roller 3 rotated by the drive motor and the reverse roller 4, the reverse shaft 5 rotated by the drive motor is rotated. The rotation is transmitted to the reverse roller 4 via the torque limiter 6, and the reverse roller 4 rotates in the reverse sheet feeding direction to return the other sheet that contacts the reverse roller 4.
After the trailing edge of the paper to be fed passes through the nip between the feed roller 3 rotated by the drive motor and the reverse roller 4, the feed clutch 21 is turned off, and the power from the drive motor to the feed roller 3 is reduced. The transmission is cut off so that the feed roller 3 can freely rotate.
The rotation of the reverse shaft 5 that is rotationally driven by the drive motor is transmitted to the reverse roller 4 via the torque limiter 6, and the reverse roller 4 is rotationally driven in the non-feed direction to be sandwiched between the reverse roller 4 and the feed roller 3. It is configured to return other printed paper.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus including a sheet feeding device. FIG. 3 is a schematic perspective view illustrating a roller and a configuration related to the roller in the first paper feeding device. FIG. 3 is a schematic diagram illustrating a first paper feeding device and a registration roller pair. 6 is a timing chart illustrating sheet feeding timing. FIG. 3 is a schematic view showing a first paper feeding device and a registration roller pair in which a pickup roller is lowered. FIG. 3 is a schematic diagram showing a first paper feeding device and a registration roller pair in which a sheet has slack in contact with the registration roller pair. FIG. 3 is a schematic diagram illustrating a first sheet feeding device and a registration roller pair in which a leading end of a sheet passes through the registration roller pair. Schematic which shows the case where several sheets of paper are pushed in between a feed roller and a reverse roller. 6 is a flowchart illustrating an example of an operation of a sheet feeding device. 1 is a schematic diagram illustrating a conventional example of a paper feeding device that feeds paper one by one. FIG. 3 is a schematic diagram illustrating a sheet fed between a feed roller and a reverse roller.

Explanation of symbols

2 Pickup roller 3 Feed roller 4 Reverse roller 5 Reverse shaft 6 Torque limiter 9 Paper feeder 13 Registration roller pair 21 Feed clutch 22 Registration sensor

Claims (6)

  A pickup roller that feeds the stacked paper; a feed roller that is disposed downstream of the pickup roller in the paper conveyance direction; and a reverse roller that contacts the feed roller. In the sheet feeding device connected to the drive motor via a feed clutch that transmits or blocks the feed roller to or from the feed roller, the feed roller and the reverse roller in which the rear end of the sheet to be fed is rotated by the drive motor After passing through the nip, the feed clutch is turned off to cut off the transmission of power from the drive motor to the feed roller so that the feed roller can freely rotate and is driven to rotate by the drive motor. The reverse shaft is rotated by means of a torque limiter. Tell La, the sheet feeding apparatus characterized by being configured to return the other sheet sandwiched between the reverse roller and the feed roller driven to rotate the reverse roller in a counter-sheet feeding direction.   At the start of paper feeding, prior to feeding the paper by the pickup roller, the drive motor rotates the reverse shaft, turns off the feed clutch, and interrupts transmission of power from the drive motor to the feed roller. The sheet feeding device according to claim 1, wherein the feed roller is in a freely rotatable state.   The feed roller and a pair of registration rollers disposed downstream of the reverse roller in the paper conveyance direction, and the paper is stopped once the leading edge of the paper is abutted against the stopped registration roller pair to form a slack in the paper. The pair of registration rollers is rotated at a predetermined timing to feed the paper, and the drive motor is stopped while the feed clutch is turned on to temporarily stop the transport of the paper. The sheet feeding device according to claim 1 or 2.   4. The paper feeding device according to claim 1, wherein the paper feeding device comprises a plurality of the paper feeding devices, and a common driving motor is used as a driving motor for the plurality of paper feeding devices. An image forming apparatus.   An image using the paper feeding device according to claim 1, wherein the driving motor in the paper feeding device is driven for a predetermined time and then stopped at the time of restart after the device is temporarily stopped due to paper jam. Forming equipment.   2. An image forming apparatus using the sheet feeding device according to claim 1, wherein a driving motor in the sheet feeding device is driven for a predetermined time when the apparatus power is turned on.

Images