JP4184641B2 - Paper feeding device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet supply apparatus that picks up sheets stored in a sheet tray one by one and supplies them to a desired location, and an image forming apparatus such as a copying machine, a printer, and a facsimile equipped with the sheet supply apparatus.
[0002]
[Prior art]
As a paper feeding device that feeds paper one by one from a paper tray of an image forming apparatus such as a copying machine, a printer, or a facsimile, a paper feeding roller that rotates in the paper feeding direction and a pressure roller that is in pressure contact with the paper feeding roller A friction separating roller type (hereinafter, referred to as FRR type) paper feeding device having a separating roller which is configured to perform a driving force in a direction opposite to the feeding direction via a torque limiter is well known. In this FRR type paper feeder, the paper feed roller and the separation roller are always in pressure contact, so when the paper tray is pulled out with the paper held in the nip between both rollers, the paper is brought into the paper feeder. It remains, causing a paper jam (paper jam). In view of this, for example, as disclosed in Japanese Patent Laid-Open No. 6-183600, a paper feeding device having a mechanism for releasing the pressure contact between the separation roller and the paper feeding roller has been proposed. However, in this prior art, since the rubber roller rotating in the reverse direction is pressed, there is a biting force between the rollers even if the driving is stopped, and the separation roller may not be released only by releasing the pressing means.
[0003]
In such a case, in the FRR system paper feeding device that always applies driving force to the separation roller with emphasis on paper separation performance, the separation rollers of all the paper feeding units are collectively driven even when the paper is conveyed by other paper feeding units. For this reason, load torque of other sheet feeding units is also applied, and torque fluctuation is given to the drive source. On the other hand, in recent years, with the diversification of paper sizes and paper types used in image forming apparatuses, a plurality of (two-stage) are set in one image forming apparatus in order to set paper cassettes that store paper suitable for each application. There are an increasing number of paper trays having about 5 stages. For this reason, when the number of paper feeding units in which the separation roller cannot be released increases, the torque limiter remains in operation, and the life of the torque limiter is shortened. In addition, the load torque may increase and the drive system may be damaged. Furthermore, it is necessary to use a motor or the like having a large output corresponding to the increase in load torque. Both of these lead to increased costs.
[0004]
Japanese Patent Application Laid-Open No. 7-137872 discloses a mechanism for forcibly releasing the separation roller. However, in recent printers and copiers, the paper feeding roller and separation roller have been reduced in size by saving space and increasing the number of paper trays, so even a slight misalignment of the roller causes a large change in the contact angle between the rollers with respect to the pressing direction. As a result, the biting force of the roller also increases. In order to forcibly release this, a mechanism having a considerably large releasing force has to be configured, which hinders space saving and cost reduction of the apparatus.
[0005]
On the other hand, in the FRR type paper feeding device, the paper feeding roller is normally driven by the calling roller until the paper fed by the paper feeding roller reaches the grip roller provided downstream in the paper transport direction. When the paper reaches the grip roller, the drive of the paper feed roller is stopped. Therefore, if the paper feed roller is always driven, the next paper is also fed continuously, which may hinder image formation. Therefore, as described above, when the sheet is conveyed to some extent, it is necessary to stop the driving of the sheet feeding roller. Therefore, even if the feed roller is provided with a one-way clutch and the drive is stopped and the shaft of the feed roller does not rotate, the feed roller moves along with the movement of the paper conveyed by the grip roller. Is driven to rotate in the direction of conveyance.
[0006]
Further, in recent years, there are many methods in which the driving of the separation roller shaft is synchronized with the driving of the paper feeding roller shaft and the separation roller is not released while waiting for the paper feeding of the other paper feeding unit. In this method, load torque of the non-use sheet feeding unit is not generated, and it is only necessary to release the separation roller when the paper tray is pulled out. Therefore, the release mechanism can be simplified, which is advantageous in terms of cost. . However, in this method, when the driving of the paper feed roller is stopped, no driving force is applied to the torque limiter of the separation roller at that time, and the friction separating function is lowered while the paper feed roller is driven to rotate. There's a problem. If the friction separating function is reduced in this way, paper double feeding is caused. Such a problem is dealt with by driving the paper feed roller to the very end of the paper and shortening the drive stop time of the paper feed roller as much as possible.
[0007]
[Problems to be solved by the invention]
However, even in such a paper feeding device, the bite between the paper feeding roller and the separation roller is accumulated while the paper feeding roller is driven to rotate with the paper conveyed by the grip roller. In some cases, the release of the separation roller is insufficient and the paper remains.
[0008]
The present invention has been made in view of the drawbacks of the prior art, and an object of the present invention is to provide a friction separation roller type paper feeding device that always applies a driving force to the separation roller, and to keep the paper remaining when the tray is pulled out with a simple configuration. It is an object of the present invention to provide a space-saving paper feeding device that prevents the above-described problem.
[0009]
Another object of the present invention is to provide a sheet feeding device capable of protecting parts without increasing the cost of a drive system or a release mechanism for a separation roller.
[0010]
Another object of the present invention is to provide an image forming apparatus including a space-saving paper feeding device that prevents paper remaining when the tray is pulled out.
[0011]
[Means for Solving the Problems]
In order to achieve the object, the first means includes a paper feed roller that feeds the paper picked up from the paper tray, and a driving force applied in a direction opposite to the paper feed roller via a torque limiter. When there is no sheet and when there is one sheet, the separation roller rotates along with the sheet feeding roller, and reverses when there are a plurality of sheets, and the urging force for urging the separation roller in a direction in pressure contact with the sheet feeding roller. Means, release means for releasing the pressure contact force of the separation roller against the paper feed roller against the biasing force of the biasing means, and reverse rotation for preventing reverse rotation of the paper feed roller due to reverse rotation of the separation roller In the paper feeding device having the prevention means, the reverse rotation prevention means is operated in conjunction with the urging operation of the urging means, and the reverse rotation prevention means is released in conjunction with the release operation of the release means. It is characterized by.
[0012]
The second means is that in the first means, the urging by the urging means and the urging release by the releasing means are performed in conjunction with the insertion / extraction operation of the paper tray with respect to the paper feeding device body. Features.
[0013]
The third means is characterized in that, in the first means, the reverse rotation preventing means is operated and released in conjunction with the insertion / extraction operation of the paper tray with respect to the paper feeding device main body.
[0014]
In the first means, in the first means, the urging and urging release by the urging means and the operation and action of the reverse rotation preventing means are interlocked with the insertion / extraction operation of the paper tray to the paper feeding device main body. Release is performed.
[0015]
The fifth means is that a driving force is applied in the opposite direction to the paper feed roller through the torque limiter to feed the paper picked up from the paper tray, and when there is no paper, In this case, the sheet feeding roller includes a separation roller that rotates along with the sheet feeding roller and reverses when there are a plurality of sheets, and a reverse rotation preventing unit that prevents the sheet feeding roller from rotating in reverse with the reverse rotation of the separation roller. The apparatus is characterized in that the reverse rotation preventing means is operated and released in conjunction with the insertion / extraction operation of the paper tray with respect to the paper feeding device main body.
[0016]
A sixth means includes a paper feeding device in the first to fifth means, and an image forming means for forming an image on the paper fed from the paper feeding device based on input image information. It is characterized by. In this case, the sheet feeding device is provided integrally or separately with respect to the image forming apparatus main body.
[0017]
In the following embodiments, the first to fourth means correspond to the first and second embodiments, the urging means corresponds to the first lever 7, and the reverse rotation preventing means corresponds to the second lever 11. Corresponding to the reverse rotation preventing member 24, the releasing means corresponds to the second lever 11, the urging member 13, and the solenoid that operates the second lever 11. Further, the projection 5a operates the second lever 11 in conjunction with the insertion / extraction operation of the paper tray, and the urging member 13 and the first lever 7 operate according to this operation. On the other hand, the fifth means corresponds to the third embodiment, and the fourth lever 62 rotates in conjunction with insertion / extraction of the paper tray, thereby restricting the rotation of the reverse rotation preventing member 24.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. Note that, in the nuclear embodiment, the same or substantially the same constituent elements are denoted by the same reference numerals, and redundant description is omitted.
[0019]
First, the first embodiment shown in FIGS. 1 to 5 will be described. 1 is a diagram showing a schematic configuration of an electrophotographic printer as an image forming apparatus to which the present invention is applied, FIG. 2 is a perspective view showing a sheet feeding unit in a state where a separation roller is pressed against the sheet feeding roller, and FIG. FIG. 4 is a perspective view showing the sheet feeding unit in a state where the pressure contact state between the separation roller and the sheet feeding roller is released, FIG. 4 is a diagram for explaining the positional relationship between the separation roller and the sheet feeding roller, and FIG. It is a fragmentary perspective view for demonstrating a type | system | group.
[0020]
In FIG. 1, the printer 50 includes a two-stage sheet feeding unit in which sheet feeding units 100 and 200 are arranged above and below, and an image forming unit 70 disposed above the sheet feeding unit. The image forming unit 70 of the printer 50 includes various units of a conventionally known electrophotographic process including a writing unit 71, a photosensitive drum 72, a developing unit 73, a transfer unit 74, and a fixing unit 75. Since this process itself is publicly known, detailed description thereof is omitted. Further, since each of the paper feeding units 100 and 200 has the same configuration, a duplicate description will be omitted, and the case of the paper feeding unit 100 will be described below as an example.
[0021]
A paper tray 5 is attached to the paper feed unit 100, and the paper in the paper tray 5 is called by a call roller 3 that is rotationally driven by a drive source (not shown), and a nip between the paper feed roller 1 and the separation roller 2. Are conveyed one by one to the pair of registration rollers by the vertical conveying device, and further conveyed to the transfer position of the image forming unit 70 in timing with the leading edge of the image formed on the photosensitive drum 72.
[0022]
As shown in FIG. 2, the principle of paper rolling in the paper feeding unit 100 is that a predetermined return force is applied in a direction opposite to the paper transport direction (hereinafter referred to as the paper return direction) by the torque limiter 4 having a predetermined idling torque. The separation roller 2 generating pressure is brought into pressure contact with the paper feed roller 1, and when two or more sheets are held in the nip, the separation roller 2 rotates in the sheet return direction so that the lowermost sheet enters the sheet tray 5. When the sheet is fed backward and there is no sheet in the nip or when only one sheet is held, the separation roller 2 is rotated by the sheet feeding roller 1 in the sheet conveyance direction.
[0023]
The paper feed roller 1 is attached to a paper feed roller shaft 18 driven by a drive source (not shown), and the separation roller 2 is attached to the separation roller shaft 6 via a torque limiter 4. Further, the gear 10 mounted on the separation roller shaft 6 is engaged with the gear 20 driven by the above-described driving source. The separation roller shaft 6 is rotatably supported by a bearing 9, and the bearing 9 is fitted in a notch portion 21a of a support plate 21 so as to be movable in the vertical direction. The bearing 9 is placed on the upper side portion 7 a of the first lever 7 that is swingably attached to the shaft 22. One end of an initial pressure spring 8 is attached to the lower side portion 7c of the first lever 7, and a protruding portion 7b extending in the horizontal direction is integrally provided in the vicinity of the lower side portion 7c. The other end of the initial pressure spring 8 is attached to a frame 30 shown schematically in FIG. 1, and the first lever 7 presses the bearing 9 upward by the action of the initial pressure spring 8, thereby separating the separation roller. 2 is brought into pressure contact with the paper feed roller 1.
[0024]
An urging member 13 extending in the axial direction of the separation roller shaft 6 is located in the vicinity of the first lever 7, and although not shown in detail, the urging member 13 can slide on the frame 30. Is attached. A claw portion 13 a is provided at one end of the urging member 13. One end of the release spring 12 is attached to the side of the urging member 13, and the other end of the release spring 12 is attached to the frame 30. Further, the end of the biasing member 13 opposite to the end provided with the claw portion 13a is linked to one end of the second lever 11 rotatably attached by the shaft 23 so as to be rotatable. ing. The second lever 11 is instructed by a solenoid (not shown) so as to be able to turn clockwise with the shaft 23 as a fulcrum. The clockwise rotation of the second lever 11 causes the biasing member 13 to slide as shown in FIG. 2, so that the claw portion 13 a is separated from the protruding portion 7 b of the first lever 7. When the solenoid is deactivated, the biasing member 13 is pulled by the release spring 12 and slides in the reverse direction, and the claw portion 13a pushes the protruding portion 7b of the first lever. Here, since the release force of the release spring 12 is set to be larger than the biasing force of the initial pressure spring 8, the pressure applied to the bearing 9 of the first lever 7 is released.
[0025]
The separating roller 2 is always given a driving force in the sheet returning direction by a separating roller shaft 6 that rotates in the direction of arrow R in FIG. The pressure contact force of the separation roller 2 to the paper feed roller 1 is the sum of the initial pressure at which the first lever 7 presses the bearing 9 upward by the action of the initial pressure spring 8 and the kicking force by the gear 10 and the gear 20. However, this kick-up force is generated only when the torque limiter 4 operates.
[0026]
However, actually, as shown in FIG. 4, the notch portion 21a of the bearing 9 and the support plate 21 has a slight gap δ in order to improve the vertical movement. As a result, the center of the separation roller 2 is deviated from the center line in the pressure contact direction to the paper feed roller 1 by the driving force. Further, due to the elastic deformation of the roller rubber part, the tangential force T between the rubbers has an angle θ from the normal direction of the pressure contact direction. Even if the driving of each roller is cut off, the paper feed roller is prevented from reverse rotation and the separation roller is prevented from reverse rotation by the driving system load, so the tangential force T remains. Even if the first lever 7 is released in this state, the separation roller 2 is prevented from falling by its own weight due to the frictional force μ · T ″ between the bearing 9 and the notch portion 21a of the support plate 21 caused by the horizontal component T ″. The pressure contact state is maintained by the vertical component T ′ of the force T. As the roller diameter decreases, the angle θ increases, so that the pressure contact force tends to increase.
[0027]
In this embodiment, an anti-reverse member 24 incorporating a one-way clutch is provided on the paper feed roller shaft 18, and the rotation of the anti-reverse member 24 is restricted by the restricting portion 11 a of the second lever 11. When the solenoid (not shown) is deactivated, the urging member 13 is pulled and slid by the release spring 12, and the second lever 11 linked to this is rotated counterclockwise, thereby restricting the restricting portion. 11 a is separated from the reverse rotation preventing member 24. Since the reaction force of the tangential force T is transmitted through the paper feed roller 1 and the paper feed roller shaft 18, the reverse rotation prevention member 24 is reversed by the separation of the second lever 11, and the tangential force T goes to cancel (the first The separation amount of the three arms may be as long as the tangential force T is eliminated. As a result, when the pressure applied to the bearing 9 of the first lever 7 is released via the biasing member 13, the separation roller 2 falls by its own weight, is released from the paper feed roller 1, and enters the state shown in FIG.
[0028]
In the sheet feeding unit 100 having the above-described configuration, the above-described solenoid (not shown) is activated during the sheet feeding operation to rotate the second lever 11 in the clockwise direction, and the sheet feeding operation is performed. Further, since the solenoid (not shown) is deactivated when the paper feeding operation is completed, the nip between the paper feeding roller 1 and the separation roller 2 is reliably released only by the releasing force of the release spring 12 as described above, and the state shown in FIG. become.
[0029]
As shown in FIG. 5, the drive unit of the sheet feeding device in this embodiment includes a motor 15 serving as a drive source via an input gear 17 on a toothed belt 16 and a separation roller drive shaft 19. Driving force is transmitted to 100 and 200. The separation roller shaft 6 of each paper feed unit is always rotating while the drive motor 15 is rotating. The paper feed roller shafts 18 of the paper feed units 100 and 200 rotate when the clutch 14 is operated. As for the solenoid (not shown), only the selected paper feeding unit is activated. In FIG. 5, only the solenoid of the paper feed unit 100 is operated, only the separation roller 2 of the paper feed unit 100 is pressed against the paper feed roller 1, and the solenoid on the paper feed unit 200 side is operated. In other words, the separation roller 2 of the paper feed unit 200 is separated from the paper feed roller 1. Therefore, no load is generated in the torque limiter 4 of the paper feed unit 200, and the drive motor 15 only has to bear the drive load of the paper feed unit 100. A drive motor with a small rated output is sufficient, and the drive source is downsized. be able to. Further, even when the sheet feeding operation is completed with the sheet left in the nip between the sheet feeding roller 1 and the separation roller 2, the nip is released when the sheet tray 5 is pulled out, so that the sheet is not caught and the sheet is not caught. Residual can be prevented.
[0030]
In the first embodiment described above, the second lever 11 is rotated clockwise by the solenoid, but the second lever 11 may be rotated clockwise by mounting the paper tray 5. . The configuration will be described with reference to FIG. FIG. 6 is a partial perspective view for explaining the third arm rotation mechanism and the drive system in the second embodiment.
[0031]
That is, a protrusion 5a is provided at the front end of the paper tray 5 of each paper feed unit 100, 200 in contact with the pushing portion 11b on the second lever 11 when the paper tray 5 is installed. The protrusion 5 a pushes the pushing portion 11 b on the second lever 11 by mounting the paper tray 5, and rotates the second lever 11 clockwise about the shaft 23. This restricts the reverse rotation preventing member 24 and presses the separation roller 2 against the paper feed roller 1. Conversely, when the paper tray 5 is pulled out, the contact between the protrusion 5a and the pushing portion 11b of the second lever 11 is released, and the second lever 11 rotates counterclockwise by the release force of the release spring 12. As a result, the restriction of the reverse rotation preventing member 24 is released, the tangential force T between the paper feed roller 1 and the separation roller 2 is eliminated, and the separation roller 2 is reliably released.
[0032]
In this example, the motor 15 as a driving source transmits driving force to the clutches 14 of the paper feeding units 100 and 200 via the toothed belt 16 and the input gear 25. The paper feed roller shaft 18 rotates when the clutch 14 is operated. At this time, the gear 26 on the paper feed roller shaft 18 drives the gear 27 on the separation roller drive shaft 19, and the separation roller 2 is driven via the separation roller shaft 6. Since the torque limiter 4 on the separation roller shaft 6 does not operate unless the clutch 14 is actuated, the driving load is only the idling torque of the clutch 14 and the driving motor 15 only has to bear the driving load of the sheet feeding unit in operation. . Therefore, the separation roller 2 can be released only when the paper tray 5 is pulled out, and the release drive of a solenoid or the like is not necessary and the cost is reduced. In addition, even when the paper feed operation is completed with the paper left in the nip between the paper feed roller 1 and the separation roller 2, the nip is released when the paper tray is pulled out, so that the paper is not caught and the paper remains. Can be prevented.
[0033]
Thus, according to the first and second embodiments described above, the urging by the first lever 7 and the urging by the second lever and the reverse rotation preventing member 24 are interlocked with the insertion and removal of the paper tray 5 from the apparatus main body. Since the release of the force and the operation of the reverse rotation prevention member 24 and the release of the operation are performed, when pulling out the paper tray 5 from the apparatus main body, the paper feed roller 1 reverses and the biting force with the separation roller 2 can be reduced. The separating roller 1 can be reliably released by the releasing force. Accordingly, it is possible to reliably prevent paper remaining when the paper tray 5 is pulled out. Further, the urging release mechanism of the separation roller 2 can be constructed at a relatively low cost by utilizing the insertion / extraction force of the paper tray.
[0034]
In the third embodiment of the present invention shown in FIG. 7, the operation and non-operation of the reverse rotation preventing member 24 are controlled in conjunction with the insertion and removal of the paper tray 5. The configuration will be described with reference to FIG. FIG. 7 is a perspective view showing a sheet feeding unit in a third embodiment of the present invention in a state where a separation roller is pressed against the sheet feeding roller.
[0035]
That is, as in the first embodiment described above, the anti-reverse member 24 with a built-in one-way clutch is provided on the paper feed roller shaft 18, and the rotation of the anti-reverse member 24 is the same as that of the first embodiment. The fourth lever 62 corresponding to the second lever 11 is regulated by a regulating part 62 a provided at one end. The fourth lever 62 is rotatably supported at its end facing the restricting portion 62a by the shaft 23, and is pushed when the paper tray 5 is mounted to rotate the fourth lever 62 in the clockwise direction. For this purpose, a push-in part 62b is formed. The fourth lever 62 is further formed with a flange 62c between the end portion on the shaft 23 side and the pushing portion 62b, and the fourth lever 62 is counterclockwise when the paper tray 5 is pulled out. One end of a spring 28 is hung. The other end of the spring 28 is attached to a frame 30 schematically shown in FIG.
[0036]
Further, the third lever 61 corresponding to the first lever 7 in the first embodiment for pressing the separation roller 2 against the paper feed roller 1 is bent at a substantially right angle, and the corner portion is swung by the shaft 22. Supported as possible. The upper side 61a of the third lever 61 is positioned so as to contact the lower part of the bearing 9, and one end of the initial pressure spring 8 is attached to the lower side 61c. The action of the third lever 61 is the same as that of the first embodiment. The action of the initial pressure spring 8 causes the first lever 7 to press the bearing 9 upward, and the separation roller presses against the paper feed roller 1. .
[0037]
Therefore, the fourth lever 62 is rotated in the clockwise direction about the shaft 23 as the pushing portion 62b is pushed by the mounting of the paper tray 5. As a result, the restricting portion 62 a of the fourth lever 62 comes into contact with the reverse rotation preventing member 24 and restricts the rotation of the reverse rotation preventing member 24.
[0038]
Conversely, when the paper tray 5 is pulled out, the fourth lever 62 is rotated counterclockwise by the force of the spring 28, and the description of the rotation of the reverse rotation preventing member 24 is released. As a result, the reverse rotation restriction of the paper feed roller 1 via the paper feed roller shaft 18 is released. At this time, even if the paper feeding state is finished in a state where the paper that has entered the nip between the paper feeding roller 1 and the separation roller 2 has entered, the paper feeding roller is caused by the reaction force of the tangential force T as shown in FIG. 1 reverses. Since the paper is also returned to the upstream of the conveyance by the reverse rotation of the paper feed roller 1, the paper is not caught and the paper can be prevented from remaining.
[0039]
As described above, in the third embodiment, the functional operation / functional operation of the reverse rotation preventing member 24 is canceled in conjunction with the insertion / extraction of the paper tray 5 from the apparatus main body, and the urging of the separation roller 2 is performed. Even without a release mechanism, it is possible to prevent the remaining of the paper when the paper tray 5 is pulled out to some extent, and to reduce the cost. In addition, the spring 28 also requires a weak force for rotating only the fourth lever 62, and the force applied as a reaction force to the paper tray 5 can be reduced. Therefore, the positioning mechanism of the paper tray 5 can be simplified, leading to cost reduction.
[0040]
【The invention's effect】
As is apparent from the above description, according to the present invention, the reverse rotation preventing means is operated in conjunction with the urging operation of the urging means, and the reverse rotation preventing means is operated in conjunction with the releasing operation of the releasing means. Since the operation is released, the paper feed roller reverses when the biasing means releases the bias, the biting force between the paper feed roller and the separation roller can be reduced, and the separation roller can be reliably released with a small release force. This eliminates an unnecessary increase in driving load, avoids an increase in driving system cost, and also protects parts. Further, it is possible to prevent paper remaining when the paper tray is pulled out.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an electrophotographic printer to which a first embodiment of the invention is applied.
FIG. 2 is a perspective view illustrating a sheet feeding unit in a state where a separation roller is pressed against the sheet feeding roller.
FIG. 3 is a perspective view illustrating a sheet feeding unit in a state in which a pressure contact state between a separation roller and a sheet feeding roller is released.
FIG. 4 is a diagram for explaining a positional relationship between a separation roller and a paper feed roller.
FIG. 5 is a partial perspective view for explaining a drive system of a paper feeding unit.
FIG. 6 is a partial perspective view for explaining a third lever rotating mechanism and a drive system in a second embodiment of the present invention.
FIG. 7 is a perspective view illustrating a sheet feeding unit according to a third embodiment of the present invention in a state where a separation roller is pressed against the sheet feeding roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Paper feed roller 2 Separation roller 3 Calling roller 4 Torque limiter 5 Paper tray 5a Protrusion 7 First lever 8 Initial pressure spring 9 Bearing 11 Second lever 12 Release spring 13 Energizing member 14 Clutch 21 Support plate 21a Notch portion 24 Reverse rotation Prevention member 30 Frame 50 Printer 61 Third lever 62 Fourth lever 70 Image forming unit 100, 200 Paper feeding unit

Claims (6)

A drive force is applied in the opposite direction to the paper feed roller for feeding the paper picked up from the paper tray and the paper feed roller via a torque limiter, and the paper feed is performed when there is no paper and when there is one paper. A separation roller that rotates with the roller and reverses when there are a plurality of sheets; an urging unit that urges the separation roller in a direction in pressure contact with the sheet feeding roller; and an urging force of the urging unit A release unit that releases a pressure contact force of the separation roller to the paper feed roller, and a reverse rotation prevention unit that prevents reverse rotation of the paper feed roller due to reverse rotation of the separation roller.
The sheet feeding device, wherein the reverse rotation preventing means is operated in conjunction with an urging operation of the urging means, and the reverse rotation preventing means is released in conjunction with a releasing operation of the releasing means. 2. The paper feeding device according to claim 1, wherein the biasing by the biasing means and the biasing release by the releasing means are performed in conjunction with an insertion / extraction operation of the paper tray with respect to the main body of the paper feeding device. 2. The paper feeding device according to claim 1, wherein the reverse rotation preventing means is operated and released in conjunction with an insertion / extraction operation of the paper tray with respect to the paper feeding device main body. The biasing and biasing release by the biasing means and the operation and release of the reverse rotation preventing means are performed in conjunction with an insertion / extraction operation of the paper tray with respect to the paper feeder main body. 1. A drive force is applied in the opposite direction to the paper feed roller for feeding the paper picked up from the paper tray and the paper feed roller via a torque limiter, and the paper feed is performed when there is no paper and when there is one paper. In a paper feeding device comprising a separation roller that rotates with a roller and reverses when there are a plurality of sheets, and a reverse rotation preventing means for preventing reverse rotation of the paper feeding roller due to reverse rotation of the separation roller,
The sheet feeding device is characterized in that the reverse rotation preventing means is operated and released in conjunction with an operation of inserting and removing the sheet tray from the sheet feeding device main body. A paper feeding device according to any one of claims 1 to 5,
Image forming means for forming an image based on input image information on a sheet fed from the sheet feeding device;
An image forming apparatus comprising:

Images