JP3882426B2 - Paper feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding device for feeding sheets stacked on a tray one by one.
[0002]
[Prior art]
In a paper feeding device used for an image forming apparatus or the like, one sheet is taken out from the paper stored on a tray and conveyed to a paper feeding path after being separated so as not to cause double feeding. It is configured to send to the recording unit or reading unit. When the paper feeding device is used as a document feeding device of an image forming apparatus, a document stacked on a document tray is picked up by a pickup roller, and a separation roller that is rotated in a paper feeding direction is set in a direction opposite to the paper feeding direction. The sheet is separated by a separating device arranged opposite to a retard roller to which a rotational force is applied, and conveyed toward the reading unit by a conveying roller device arranged in the document conveying path. And after reading the said original, it is comprised so that it may send out toward a discharge tray.
[0003]
The pickup roller provided in the paper feeding device performs the operation of feeding the paper toward the separating device. When the paper reaches the conveying roller device arranged in the downstream portion of the paper separating device, the conveying speed in the conveying roller device is increased. Since it is faster than the conveying speed of the sheet separating device and the pickup roller, a mechanism (one-way clutch) is provided that stops driving transmission to the sheet separating device and the pickup roller and idles. In addition, a one-way clutch mechanism using a coil spring is provided for driving transmission to the pickup roller. When the pickup roller is driven, the coil spring is wound so as to be tightened to rotate the drive shaft. To communicate.
[0004]
[Problems to be solved by the invention]
In order to transmit the driving force to the pickup roller of the paper feeding device, a conventional device uses a mechanism in which an idler gear is arranged on a support arm that swings up and down with respect to the drive shaft of the separate roller, and the idler gear is used. ing. With such a mechanism, when the paper accumulated on the document tray is picked up, the pickup roller comes into contact with the upper surface of the accumulated paper by the lowering of the support arm, and the paper is taken out from the upper surface by the subsequent rotation of the pickup roller. It is fed to the nip position between the roller and the retard roller.
[0005]
When an attempt is made to increase the paper stack amount of the tray, a step is formed in the vicinity of the nip position of the tray, and an inclined surface is formed in the vicinity thereof. In this case, in the conventional mechanism, the pickup roller is lowered to the inclined surface, and when the accumulated paper is reduced, the paper is stressed, or the leading edge of the paper is shifted from the inclined surface, and the action of the pickup roller is caused. As a result, the paper is not taken out smoothly.
[0006]
In order to solve this problem, it is conceivable to lengthen the support arm so that the pickup roller descends to the flat part of the tray. In this case, the diameter of the idler gear is increased or the number thereof is increased. It is necessary to increase. However, when the gear has a large diameter, there is an inconvenient situation that it protrudes from the arm member that supports the pickup roller and blocks the paper conveyance path, and the arrangement of a plurality of gears is due to an increase in the number of parts. There is also the problem of increased costs.
[0007]
The present invention is intended to solve the problems of the conventional drive transmission mechanism. By using a drive transmission mechanism using a belt, a paper feed function capable of performing a pickup function without any trouble even when the paper stacking amount on the tray is increased. The device is intended to be provided.
[0008]
[Means for Solving the Problems]
The present invention relates to a sheet feeding device in which a drive shaft provided with a separation roller for separating and transporting a sheet performs rotational drive transmission to the pickup roller from the drive shaft. The present invention provides a sheet feeding device in which a pickup roller for taking out a sheet from a tray is supported via a support arm member, and rotational drive transmission to the pickup roller is performed from the drive shaft. A one-way clutch, an arm elevating torque limiter, and an overload buffering clutch for transmitting drive from the roller shaft to the pickup roller are provided on the roller shaft of the pickup roller.
[0009]
In the invention, it is preferable that the belt is stretched between a clutch pulley provided on the drive shaft and a driven pulley provided on the roller shaft. Therefore, drive transmission from the drive shaft to the pickup roller is facilitated.
[0010]
Furthermore the present invention, the separating roller is rotatably supported relative to the drive shaft, and sliding along the drive shaft to separate roller side with the rotation of the normal of the drive shaft, the separate roller and cam coupled to When drive force is transmitted to the separate roller and a rotational force that is opposite to the normal rotation acts on the drive shaft, the cam coupling is released by sliding in the opposite direction to the normal rotation. A separate hub, and the clutch pulley is fitted into the separate hub, and the cam is coupled to and released from the hub by sliding movement along the axial direction of the separate hub. To do. By the operation of the separate hub, drive transmission to the separate roller and the pickup roller is performed, and the drive transmission is also cut off by the separate hub.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The drive transmission mechanism of the present invention will be described according to the illustrated example. FIG. 1 shows the structure of the pickup roller support and transmission mechanism, FIG. 2 is an explanatory view seen from the side, and FIG. 3 is an exploded perspective view of the drive transmission mechanism from the drive shaft to the separate roller 7 and the pickup roller 4. It is shown in the figure. In the example of the paper feeding device shown in FIGS. 1 and 2, the sheets stacked and accommodated in the tray are taken out by the pickup roller 4 toward the conveyance path and rotated in the paper feeding direction of the paper separating device 6 (see FIG. 4). The separating roller 7 and the retard roller 8 rotated in the direction opposite to the conveying direction are used to handle the multi-feed sheets and separate them one by one before sending them out to the next processing step. I have to.
[0013]
In the paper feeding device, the drive shaft 31 of the separation roller 7 is driven by a drive source of the device body (not shown), and the drive shaft 31 is driven in response to a command to take out the paper from the paper tray. The separate roller 7 is driven. Then, the rotation of the drive shaft 31 is transmitted to the pickup roller 4 via the belt 25 provided in the drive transmission device 30 to press the pickup roller 4 against the paper, and the pickup roller 4 is rotated to separate the paper. 7 to carry out the paper feeding operation. Further, as in a sheet feeding device that is generally used in the past, a sheet is fed at a speed higher than the conveyance speed of the sheet feeding device by the conveyance roller device 11 disposed in the conveyance path 10 as shown in FIG. Then, the separation roller 7 is idled and the pickup roller 4 is returned to a position not in contact with the sheet so as to cope with the next sheet feeding operation.
[0014]
In the drive transmission device 30 configured to perform the above-described operation, a drive force transmission pin 32 is provided on the drive shaft 31 that is pivotally supported by the frame of the device body. The drive shaft 31 is detachable. The separation hub 40 that is movable to the left and right in the axial direction of the drive shaft 31 is provided with an oblique groove (spiral groove) 42, and the pin 32 is provided in the oblique groove 42. As the shaft 31 rotates, the pin 32 moves in the oblique groove 42, and the pin 32 comes into contact with the wall surface of the groove, whereby drive is transmitted from the drive shaft 31 to the separate hub 40.
[0015]
Further, since the groove is provided obliquely, the separation hub 40 can be moved along the drive shaft 31 by the movement of the pin 32. Further, the driving force is transmitted to the drive system of the pickup roller 4 and the swing system of the support arm 5 by using the belt 25 wound around the clutch pulley 35 that is driven and transmitted by the separate hub 40. ing.
[0016]
A belt 25 for transmitting drive between the pickup roller 4 and the separate roller 7 is constituted by a timing belt, and a pulley 58 disposed on the drive shaft 31 and a pulley 58 provided on a roller shaft 50 of the pickup roller 4. It is stretched over. By performing the drive transmission by the belt 25, there is an advantage that the drive transmission can be easily performed without being affected by the length of the support arm 5, as compared with the case of using the conventional gear transmission means.
[0017]
In other words, in the case where the drive of the separation roller 7 is transmitted to the pickup roller 4 by the idler gear as in the prior art, if the amount of paper stack in the tray 3 is increased, the step between the position where the paper is taken in by the pickup roller and the tray 3 Therefore, the pickup roller 4 cannot move down to the flat portion of the tray 3, and there is a problem that the sheet is stressed when the number of sheets that can be accumulated is reduced.
[0018]
In order to solve the problem of stress on the paper, when the pickup roller is lowered on the flat portion of the tray, the distance between the rollers 4 and 7 becomes long. It is necessary to arrange gears. In the case of using a meniscus gear, it becomes a big problem that needs to be solved, such as the arrangement of gears to avoid protruding into the paper feed path. On the other hand, when the belt conducting means is used, the interval between the pickup roller 4 and the separation roller 7 can be arbitrarily set, and even when a groove is formed so that a large amount of documents can be stored in the document tray, The taking-out action can be performed satisfactorily. Further, since the belt conducting means is used, a reinforcing member can be added to an intermediate portion between the pickup roller 4 and the separating roller 7 of the arm member.
[0019]
In FIG. 2 shown as a side view of the drive transmission device, a pickup roller 4 is supported on a drive shaft 31 that supports a separation roller 7 via a swingable support arm 5. Arm raising means by an arm spring 27 is provided for the support arm 5, and both end portions of the arm spring 27 are engaged with the locking member 2 a of the upper frame and the locking member 5 a of the support arm 5, respectively. The operation of holding the support arm 5 in the state indicated by the solid line in FIG. When the paper stored in the paper tray 3 is sent out by the pickup roller 4, the support arm 5 is lowered using the function of the torque limiter 60 shown in FIG. 1 and pressed onto the paper. Synchronize with rotation to perform the feeding action.
[0020]
In the pickup roller 4 provided in the drive transmission device, the rotation of the drive shaft 31 of the separate roller 7 is transmitted from the pulley 36 via the belt 25 to the pulley 58, and the roller shaft 50 is transmitted from the spring clutch 55 via the fixed flange 51. Rotate. A torque limiter 60 including a compression spring 63 is interposed between the support arm 5 and the friction plate 61 provided on the end face of the pulley 58 at the side of the roller shaft 50.
[0021]
In the first stage where the rotation of the drive shaft 31 is transmitted to the roller shaft 50, the rotation of the drive shaft 31 is transmitted to the pulley 58 via the pulley 36 and the belt 25, but between the pulley 58 and the support arm 5. Since the torque limiter 60 is interposed in this, this rotational force acts in a direction to move the support arm 5 downward against the force of the arm spring 27. As a result, the support arm 5 is lowered and the pickup roller 4 is pressed against the paper stored in the tray. When the pickup roller 4 is pressed against the paper, the lowering of the support arm 5 is prevented, so that the pulley 58 is rotated, and this rotation is applied to the pickup roller 4 via the spring clutch 55 and the one-way clutch 54. Then, the sheet is fed by the pickup roller 4.
[0022]
As described above, the sheet is sent out from the sheet separating device 6 toward the conveyance roller device 11 in the downstream portion, and the leading end portion of the sheet is conveyed by the conveyance roller device 11. Since the conveyance speed by the conveyance roller device 11 is set to be higher than the conveyance speed of the separation roller 7 and the pickup roller 4 of the sheet separating device 6, the drive transmission to the separation roller 7 and the pickup roller 4 is performed by the one-way mechanism. Will be stopped. As a result of the rotation transmission to the pulley 36 and the pulley 58 being cut off, the lowering action of the support arm 5 is eliminated, and the support arm 5 moves the pickup roller 4 upward about the drive shaft 31 by the force of the spring 27. It swings and stops at a position where it waits corresponding to the next sheet feeding operation.
[0023]
The rotation of the shaft 31 is transmitted to the separate roller 7 from the pin 32 via the separate hub 40. For drive transmission to the pickup roller 4, the drive transmission from the separate hub 40 to the belt 25 via the clutch pulley 35 is transmitted. Is done. As shown in FIG. 1, the separate roller 7 is provided with a roller cylinder 33 that supports a rubber roller member with respect to the drive shaft 31 so as to be freely rotatable. The part is provided with an engaging claw 34.
[0024]
The separation hub 40 has a driving claw member 43 disposed at the end of the substantially cylindrical main body 41 on the roller side, and for driving transmission to the pickup roller 4 side in the outer peripheral direction of the other end of the main body. The driving claw 44 is provided so as to protrude. A pin 32 is detachably inserted into a pin insertion hole 32 a provided in the drive shaft 31, and an inclined groove 42 corresponding to the pin 32 provided in the drive shaft is provided in the main body 41 of the separate hub 40. . The pin 32 moves relative to the oblique groove 42 to move the separate hub 40 in the axial direction of the drive shaft 31. When the separate hub 40 presses the separate roller 7, the drive claw The member 43 engages with the engaging claw 34 of the roller cylinder 33 to transmit the rotation of the shaft to the roller. A drive claw 44 formed to project from the outer peripheral portion of the separate hub 40 transmits drive to the clutch pulley 35, and the clutch pulley 35 is rotated so that the belt 25 is wound around the pulley 36. Drive is transmitted toward the pickup roller 4.
[0025]
The clutch pulley 35 includes a substantially cylindrical body portion 37 and a pulley 36 integrally provided at an end opposite to the roller 7. The clutch pulley 35 protrudes from the body portion 37 on the inner surface of the pulley and is engaged by a claw. 38 is provided. As shown in FIG. 1, the separation hub 7 is inserted into the clutch pulley 35 and combined with the separation roller 7, and the side of the roller 7 and the other side of the separation hub 40 are connected to the support arms 5 on both sides. Position and regulate in between. By driving the drive shaft 31, the drive claw member 43 is engaged with the engagement claw 34 of the separate roller 7, and the drive shaft is driven in the paper feeding direction (the direction indicated by the arrow ■) to rotate the drive shaft 31. Is transmitted to the separation hub 40 via the pin 32, and the separation roller 7 whose one end is regulated by the support arm 5 is driven in the direction of arrow (2). The rotation of the separate hub 40 rotates the clutch pulley 35 via the meshing portion of the drive claw 44 and the engaged claw 38, and the drive transmission to the pickup roller 4 is performed via the pulley 36.
[0026]
When the separation roller 7 is driven to separate the sheets one by one, and the feeding operation is performed in the conveyance path, the leading edge of the sheet to be fed is disposed in the downstream part of the conveyance path, and is faster than the separation roller 7. When the sheet is nipped by the rotating conveying roller device 11 and is conveyed at a high speed by the conveying roller device 11 rotated at a high speed, the separating roller 7 is pulled by the high-speed moving sheet and the separation roller 7 is driven. It is rotated at a speed faster than the drive speed by 31. As described above, when the rotation speed of the separation roller 7 is high with respect to the drive shaft 31 rotating at a constant speed, the drive claw member 43 of the separate hub 40 and the engagement claw 34 of the roller 7 are used. Therefore, the drive claw member 43 and the engagement claw 34 are disengaged from each other, and the slopes of both protrusions slide.
[0027]
Then, when the separate hub 40 moves in a direction away from the separate roller 7, the engagement between the drive claw 44 and the engaged claw 38 is released. Since the pin 32 provided on the drive shaft 31 moves along the oblique groove 42 in a direction away from the separation roller 7, the engagement between the drive claw 44 and the engaged claw 38 is released, and the rotation of the drive shaft 31 is separated. In this state, no transmission is made to the roller 7 and the clutch pulley 36. In a state in which the sheet is fed at a high speed by the conveyance roller device 11 disposed in the downstream portion of the conveyance path, even if the drive shaft 31 is driven at a constant speed, the separation roller 7 and the pickup roller 4 are not moved. When the drive transmission by the drive shaft 31 is stopped and the paper transmission operation is performed using the drive transmission mechanism provided in the separate roller 7 shown in FIG. When the conveyance by the roller device 11 is performed, the separation hub 40 moves in a direction away from the separation roller 7 with respect to the separation roller 7 rotated by the movement of the sheet. Due to the movement of the separate hub 40, the engagement between the drive claw 44 and the engaged claw 38 is released, and the drive transmission from the drive shaft 31 to the clutch pulley 35 is also cut off. When the rear end of the sheet is separated from the separating roller 7, the reaction of the engaging claw 34 with respect to the driving claw member 43 is eliminated. As a result, the separation hub 40 is pushed again toward the separation roller, and the claw members are engaged with each other so that the next sheet feeding operation can be dealt with.
[0028]
As described above, the grooved drive transmission device can be applied to the device shown in FIG. 4, and is provided in the automatic document feeder 1 used in combination with the image reading device, so that the document stored in the tray can be received. It can be configured that an image is read by a reading unit arranged in the conveyance path while the sheet is being conveyed one by one. In the automatic document feeder 1 shown in this embodiment, a laterally substantially U-shaped conveyance path 10 is disposed in the apparatus main body, and a large-diameter driving roller 14 is disposed at a bent portion of the conveyance path to convey the document. A document tray 3 is provided at the entrance of the road.
[0029]
In order to convey the document in the conveyance path 10, a pickup roller 4 is arranged on the upper portion of the tray 3 via a swingable support arm 5, and a separation roller 7, a retard roller 8, A sheet separating device 6 is provided. The sheet separating device 6 is a separation roller 7 driven in the sheet feeding direction, and a retard roller 8 driven in the direction opposite to the sheet feeding direction, similarly to a device provided in a sheet feeding device such as a general copying machine. Are placed facing each other. Then, when a plurality of documents taken in by the pickup roller 4 overlap, only the top one is separated and sent to the transport roller device 11 in the transport path, and the other document is returned to the tray side. Configure as a thing.
[0030]
On the downstream side of the paper separating device 6, a conveying roller device 11 in which a driving roller 12 and a press roller 13 are combined is provided, and the paper is supplied toward a conveying region by the large-diameter driving roller 14. In the conveyance area of the large diameter driving roller 14, a platen 18 is provided near the lower part of the shaft core of the large diameter driving roller 14 between the portions where the press rollers 15 and 16 press the paper against the large diameter driving roller 14. Then, the image is read by a scanning device positioned below the platen 18. Further, a conveyance path is provided substantially horizontally from a portion nipped and conveyed by the large-diameter driving roller 14 and the press roller, and a discharge roller device 17 is disposed at the end of the conveyance path, and the document after reading is discharged to the discharge tray. To send out towards the.
[0031]
In the transport roller device 11 disposed in the transport path 10, the upper frame 2 is provided with a press roller support unit 20 that supports the press rollers 13 and 15 via a stay 21 that is fixedly provided on the frame. ing. The press roller support unit 20 is provided with a base bracket 23 on a stay 21 provided on the upper frame 2 of the apparatus, and press rollers 13 and 15 are disposed at both ends of the base bracket 23, respectively. A nip pressure with respect to the original is set, and the conveying action in the conveying path 10 can be performed in a good state. An action of pressing the pickup roller 4 against the document (paper) loaded on the tray 3 and an operation of applying rotation to the roller 4 and feeding the document toward the conveyance path are applied to the drive shaft 31. Along with driving of the provided separate roller 7, it can be performed via a drive transmission device.
[0032]
Note that the drive transmission device shown in the above embodiment is not only used in the document conveying device of FIG. 4, but also applied to a device that feeds sheets one by one from a tray in a recording paper feeding device of the image forming apparatus. Is possible. For example, even when a sheet is conveyed to each section of the image forming apparatus and an image is recorded, the sheet can be separated and conveyed from the sheet feeding tray, thereby simplifying the structure of the sheet feeding apparatus. Is possible. Further, in the drive transmission mechanism, a drive transmission separate operation is performed without using a pressing means such as a spring in order to perform a drive transmission operation to the pickup roller 4 and a paper conveyance operation by the roller. The configuration of the drive transmission member in the transmission device that moves the hub 40 along the drive shaft 31 can be simplified, and there is no problem that labor is required for maintenance.
[0033]
【The invention's effect】
This apparatus is configured as described above, and a pickup roller for taking out a sheet from a tray is supported by a drive shaft having a separation roller for separating and conveying the sheet via a support arm member, In the paper conveying apparatus in which the rotational drive transmission to the pickup roller is performed from the drive shaft, since the gear mechanism is not used for the drive transmission to the pickup roller, the degree of freedom in designing the transmission mechanism can be improved. . That is, even if a step is provided in the tray in order to increase the stack amount of sheets on the tray, the length of the arm can be increased without any problem accordingly. Further, the drive transmission from the drive shaft to the pickup roller can be easily performed, and the drive transmission to the pickup roller and the operation of separating the pickup roller from the tray can be easily performed.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an apparatus.
FIG. 2 is a side view of the apparatus of FIG.
FIG. 3 is an exploded perspective view illustrating drive transmission from a drive shaft to a separation roller 7 and a pickup roller 4;
FIG. 4 is an explanatory diagram illustrating a configuration of a sheet feeding device.
[Explanation of symbols]
1 automatic document feeder, 2 upper frame, 4 pickup roller,
6 paper separating device, 7 separate roller, 11 transport roller device,
14 Large-diameter drive roller, 25 Endless belt, 31 Drive shaft, 35 Clutch pulley, 36 Pulley, 40 Separate hub, 54 One-way clutch,
55 Spring clutch, 58 driven pulley, 60 torque limiter

Claims (3)

A drive roller having a separation roller for separating and conveying paper is supported by a pickup roller for taking out the paper from the tray via a support arm member, and rotational drive transmission to the pickup roller is performed from the drive shaft. In the sheet feeding device, the drive transmission is performed by an endless belt , and the one-way clutch, the arm lifting torque limiter, and the overload buffer for transmitting the drive from the roller shaft to the pickup roller are transmitted to the roller shaft of the pickup roller. A paper feeding device provided with a clutch. 2. The sheet feeding device according to claim 1, wherein the belt is stretched between a clutch pulley provided on the drive shaft and a driven pulley provided on the roller shaft. The separating roller is rotatably supported relative to the drive shaft, and sliding along the drive shaft to separate roller side with the rotation of the normal of the drive shaft, the separate roller and cam coupled to the drive transmission to the separating roller When a rotational force that is opposite to normal rotation is applied to the drive shaft, it has a separate hub that slides in the opposite direction to that during normal rotation and the cam coupling is released. 3. The clutch pulley according to claim 2, wherein the clutch pulley is fitted into the separate hub, and the hub is cam-coupled and released by sliding movement along the axial direction of the separate hub. Paper feeder.

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