JP4123072B2 - Paper conveying apparatus and image forming apparatus - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
In order to form an image by an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, or a multi-function machine or printing machine having a plurality of these functions, the present invention automatically reads a plurality of originals and reads image data. The present invention relates to an automatic document conveyance device that enables printing, a paper conveyance device such as a paper feeding device that conveys a plurality of recording papers and can write image data, and an image forming apparatus including these paper conveyance devices.
[0002]
[Prior art]
For example, in an automatic document feeder provided in an image forming apparatus, documents stacked on a document table are separated one by one and conveyed to an image reading unit, and image data described on a document surface is read by optical scanning. .
[0003]
2. Description of the Related Art Conventionally, an automatic document feeder that discharges a document placed on a document placement table from the document placement table and sends it to a conveyance path presses the document against a pickup roller by a movable pressing plate and rotates the pickup roller to rotate the document. Generally, it is configured to feed paper. In such an automatic document feeder, the pickup roller is generally fixedly attached to an opening / closing cover or the like. Such a situation also applies to the recording paper feeding device provided in the image forming apparatus, and the paper feed unit pickup roller is fixed to the image forming apparatus main body.
[0004]
[Patent Document 1]
JP2001-20569A
[Problems to be solved by the invention]
Therefore, for example, in an automatic document feeder, when a document bundle is pressed against a pickup roller by driving a movable pressing plate, a large impact sound is generated due to a collision between the movable pressing plate on which the document bundle is placed and the pickup roller. Has occurred. Further, vibration may be transmitted to the opening / closing cover or the like due to the collision.
[0005]
The present invention has been made in view of the above points, and has reduced the impact noise, reduced noise and improved durability, a sheet conveying apparatus such as an automatic document conveying apparatus or a sheet feeding apparatus, and these sheet conveying apparatuses. An object of the present invention is to provide an image forming apparatus including the apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a paper transport device according to the first invention of the present application is provided in a paper transport device on which a paper base on which a document, recording paper, etc. (hereinafter referred to as a document) is mounted, A movable pressing plate for biasing a document or the like loaded on the table upward to the paper table, and a biasing direction of the movable pressing plate are provided to be opposed to the paper table, and biased upward by the movable pressing plate to the paper table. A pick-up roller that abuts on the original document and the like, and sends the original document and the like from the paper table to the conveyance path by rotation;
The pickup roller is attached to a support member pivotally supported on a rotation drive shaft of the transport roller so as to be movable up and down, a damper attached to a casing and a tip of the support member abuts, and the support An impact absorbing mechanism is formed from an elastic member that urges the member to rotate, and the impact absorbing mechanism absorbs an impact when the movable pressing plate presses a document or the like loaded on the paper table to the pickup roller. It is characterized by doing so.
[0007]
The elastic member may be a torsion coil spring having a coil portion mounted coaxially with a rotation drive shaft of the transport roller.
[0009]
In the sheet conveying apparatus configured as described above, energy can be diffused by an impact between the movable pressing plate and the pickup roller, and the impact sound can be reduced. Further, since vibration is less transmitted to the apparatus main body, it is useful for improving the reliability of the entire apparatus.
[0010]
In particular, the shock absorbing mechanism includes a damper that is attached to the casing and a tip of the support member comes into contact with , and an elastic member that is provided on the rotation drive shaft of the support member and urges the support member to rotate. Therefore, the vibration of the pickup roller can be converged in a short time, not only can the impact sound absorbing effect be enhanced, but also a stable document feeding operation can be ensured.
[0011]
An image forming apparatus according to a second invention of the present application is an image forming apparatus in which the paper conveying device according to the first invention of the present application is mounted as a document conveying device or a paper feeding device. In such an image forming apparatus, it is possible to reduce the impact sound and to improve the reliability of the entire image forming apparatus.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an automatic document feeder, which is an optimum embodiment of a sheet feeder according to the present invention, will be described with reference to the drawings. The same applies to the recording paper feeding device, and the present invention is not limited to this embodiment. FIG. 1 is an overall configuration diagram of an image forming apparatus 10 equipped with an automatic document feeder 20 according to the present invention.
[0013]
The image forming apparatus 10 includes an automatic document feeder 20, an image reading unit 30, an image processing unit 35, an image forming unit 40, a cassette paper feeding unit 50, a fixing device 60, a paper discharge unit 70, and a reprint for automatic two-sided copying. Conveying means 90 is provided. An image reading unit 30 is mounted on the upper part of the main body of the image forming apparatus 10, and an automatic document feeder 20 is mounted thereon.
[0014]
The automatic document feeder 20 includes a document table 22, a paper discharge table 29, a document pressing plate 26, a plurality of roller groups 23, 24, and 24A, and a conveyance path. The document table 22 has a sheet feeding tray on which a plurality of documents can be set. A pair of regulating plates (not shown) for positioning in the width direction of the document are provided on the sheet feeding plate so as to be movable in the width direction. Yes. On a paper discharge tray 29 disposed below the document table 22, a document sent to the conveyance path by the paper feed mechanism 21 is discharged and placed after the image is read.
[0015]
In addition to the document pressing plate 26, the paper feeding mechanism 21 of the automatic document feeder 20 is provided with three types of rollers: a pickup roller 23, a conveyance roller 24, and a separation roller 24A. The document placed on the document table 22 with the first surface facing upward is urged upward by the document pressing plate 26 and comes into contact with the pickup roller 23, and is discharged from the document table 22 by the rotation of the pickup roller 23. Then, the sheets are separated one by one by the conveying roller 24 and the separation roller 24A and sent to the conveying path.
[0016]
The image reading unit 30 includes a light source L that irradiates a document and a scanning unit 31 including a mirror, two mirrors 32 that guide reflected light, an imaging lens 33, and a CCD image sensor 34 (hereinafter referred to as a CCD sensor). Yes.
[0017]
In the image reading unit 30, when the original passes through the slit glass 27 provided in the conveyance path, the image data of the original is read by the scanning unit 31, passed through the two mirrors 32 and the imaging lens 33, and then the CCD sensor. 34 is imaged.
[0018]
The CCD sensor 34 converts the read optical image into electronic image data and sends it to the image processing unit 35. The image processing unit 35 performs analog processing, A / D conversion, shading correction, image compression processing, and the like on the electronic image data, and then conveys the digitized image information data to the image forming unit 40.
[0019]
The image forming unit 40 has a photosensitive drum 1 as an image carrier on the surface of which a latent image is formed, and the photosensitive drum 1 is arranged in the order of operation along the outer peripheral surface of the photosensitive drum 1. A charging device 41 that charges the surface substantially uniformly, an exposure device 42 that writes an electrostatic latent image on the surface of the photosensitive member, and a toner that is transferred to the latent image formed on the surface of the photosensitive drum 1 to form a toner. A developing device 43 that forms an image, a transfer device 44 that transfers the toner image on the surface of the photoreceptor to the recording paper P, and a cleaning device 45 that cleans the surface of the photoreceptor drum 1 after the transfer are disposed.
[0020]
The exposure device 42 of the image forming unit 40 electrically modulates the semiconductor laser based on the digitized image information data, and performs sub-scanning with a polyhedral reflector (polygon mirror) and a lens group through a collimator lens. Further, the photosensitive drum 1 is rotated to perform main scanning, and the electrostatic latent image is reproduced on the photosensitive drum 1.
[0021]
Prior to exposure, a predetermined surface charge is imparted to the photosensitive drum 1 by corona discharge of the charging device 41. However, the laser beam irradiation reduces the charge at the exposed portion in accordance with the exposure amount, resulting in a result. As described above, an electrostatic latent image corresponding to the image information data is formed on each photosensitive drum 1. The electrostatic latent image is visualized by the developer toner supplied from the developing device 43 and becomes a toner image.
[0022]
On the other hand, a cassette paper feeding unit 50 is provided at the lower part of the main body of the image forming apparatus 10. In the paper feed cassette 51 for storing the recording paper P, there is disposed a movable plate 52 whose free end is always urged upward by an urging means such as a leaf spring, and the recording paper P placed thereon is arranged. The uppermost one is configured to contact the pickup roller 53.
[0023]
The recording paper P in contact with the pickup roller 53 is discharged from the paper feed cassette 51 and separated one by one by the paper feed roller 54 and the separating roller 54A, and then guided to the registration rollers 56 by being guided by a plurality of intermediate rollers 55. Is done.
[0024]
The conveyed recording paper P is fed to the transfer device 44 by the registration roller 56 at a paper feed timing, and the toner image formed on the photosensitive drum 1 is collectively transferred onto the recording paper P by the transfer device 44. . The recording paper P to which the toner image has been transferred is conveyed to the fixing device 60 and fixed by the fixing device 60. As shown in FIG. 1, the recording paper P sent out from the paper feed cassette 51 is transported to the fixing device 60 through a transport path A formed in a substantially vertical direction.
[0025]
The recording paper P heated for the fixing process is cooled by a cooling fan (not shown), is sandwiched between paper discharge rollers 71, discharged outside the apparatus, and placed on the recording paper discharge table 72. Alternatively, the recording paper P that has been subjected to single-sided image processing and sent to the re-conveying means 90 by the paper discharge path switching plate 73 is again subjected to double-sided image processing in the image forming unit 40 and then discharged by the paper discharge roller 71 of the paper discharge unit 70. The paper is placed on the recording paper discharge table 72.
[0026]
FIG. 2 is an overall configuration diagram of the automatic document feeder 20. Hereinafter, the automatic document feeder 20 which is one embodiment of the present invention will be described in detail with reference to FIG. The automatic document feeder 20 has a reverse conveyance path for reversing the document with respect to the image reading unit 30 so that the image data on both sides of the document can be read by one operation.
[0027]
The conveyance path is divided into three parts: a feeding path P1, a paper discharge path P2, and a reverse path P3. The paper feed path P1 is a path for guiding the document to the image reading unit 30, and the paper discharge path P2 is a path for discharging the document to the paper discharge table 29 and placing it. The inversion path P3 is a bypass path for inverting the upper and lower surfaces of the document and passing it over the slit glass 27 from which the image data of the document is read.
[0028]
These paths are switched by switching gates 201 and 202. Switching from the paper discharge path P2 to the reversing path P3 is performed by the switching gate 202, and switching from the feeding path P1 to the reversing path P3 is performed by the switching gate 201. The plurality of roller groups 25 and the like serve as driving sources for moving the document.
[0029]
A feeding path P1 connected to the document table 22 includes a document pressing plate 26, a pickup roller 23, a conveying roller 24, a feeding roller 21 including a separation roller 24A, a registration driving roller 25A, and a plurality of registration driven rollers 25B. Has been. During document feeding, the document pressing plate 26 is raised by the rotation of the drive shaft 261 to press the upper end of the document against the pickup roller 23, and the document is fed from the document table 22 to the transport roller 24 by the rotation of the pickup roller 23.
[0030]
At this time, if the document is double-fed, the load torque changes. Therefore, the torque limiter is activated by the change of the load torque, and the separation roller 24A rotates reversely to separate the documents one by one. As a result, only one uppermost document is guided by the conveyance roller 24 and moves on the paper feed path P1 to the registration driving roller 25A and the registration driven roller 25B. The registration driving roller 25A and the registration driven roller 25B correct the bending of the fed document.
[0031]
A switching gate 201 is disposed at the coupling point between the paper discharge path P2 and the reverse path P3. The switching gate 201 is normally opened so as to directly guide the document to the image reading unit 30. The document passes through the switching gate 201 and is then fed by a read roller 203 disposed downstream of the switching gate 201. Is taken out and sent onto the slit glass 27.
[0032]
A switching gate 202 for switching between the paper discharge path P2 and the reversing path P3 is provided on the downstream side of the slit glass 27, which is a coupling point with the image reading unit 30. The switching gate 202 is normally opened so as to guide the document to the sheet discharge roller 28, and the document is placed on the sheet discharge table 29 outside the apparatus by the sheet discharge roller 28 through the sheet discharge path P2. .
[0033]
When the switching gate 202 is switched, the paper discharge path P2 communicates with the reverse path P3. In this case, the document is sent from the paper discharge path P <b> 2 to the reverse path P <b> 3 and is sandwiched between the reverse conveyance rollers 204. The reverse conveying roller 204 rotates while pinching the original and places the original on the reverse path P3.
[0034]
When the original passes through the switching gate 202, the switching gate 202 is closed, the reverse conveying roller 204 rotates in the reverse direction, and the original is sent again to the paper feed path P1. At this time, the switching gate 201 is switched, and the reversing path P3 communicates with the sheet feeding path P1.
[0035]
When the automatic document feeder 20 reads one side of a document, the document fed from the transport roller 24 passes from the feeding path P1 over the slit glass 27 of the image reading unit 30 and passes through the sheet discharge path P2. As described above, the switching gate 202 guides the document to the discharge roller 28 and discharges the document to the discharge table 29.
[0036]
When reading both sides of the document, the document fed from the transport roller 24 is fed from the feed path P1 to the reversing path P3 switched by the switching gate 201. When the original enters the reversing path P3, the switching gate 201 is switched, and the original is again sent out to the feeding path P1 by the reverse conveying roller 204. As a result, the document is inverted and the image reading unit 30 reads one-sided document data.
[0037]
After that, the document is reversed by entering the reversing path P3 which is switched by the switching gate 202 and communicated from the paper discharge path P2. The original is sent again to the feeding path P1 by the reverse conveying roller 204, and the image data on the opposite side of the original is read by the image reading unit 30. Thereafter, the original is guided to the paper discharge roller 28 through the paper discharge path P <b> 2 and discharged onto the paper discharge tray 29.
[0038]
FIG. 3 is a block diagram showing a paper feed mechanism 21 having an impact absorbing mechanism which is the gist of the present invention. The paper feed mechanism 21 includes a document pressing plate 26, a pickup roller 23, a transport roller 24, and a separation roller 24A.
[0039]
The transport roller 24 has a drive shaft 242 rotatably supported on the casing 200, and the roller member attached to the outer peripheral surface is rotated by the rotation of the drive shaft 242. A separation roller 24A is in contact with the outer peripheral surface of the conveyance roller 24. The document is sandwiched between the pressure contact portions between the conveyance roller 24 and the separation roller 24A, and the document is sent out to the conveyance path by rotation.
[0040]
On the upstream side of the conveying roller 24, a pickup roller 23 for discharging the originals on the original pressing plate 26 one by one is disposed. The pickup roller 23 composed of a rubber roller is rotationally driven in conjunction with the rotation of the conveying roller 24 and discharges the document from the document table 22 by the rotational frictional force between the document on the document table 22 and the pickup roller 23.
[0041]
The pickup roller 23 is supported by a support member 232, and the support member 232 is pivotally supported so as to move up and down about the rotation drive shaft 242 of the transport roller 24. It is possible to move up and down with respect to the pressing.
[0042]
The upper end of the free end of the support member 232 located on the opposite side of the rotation driving shaft 242 of the transport roller 24 is in contact with the damper 231 to restrict the vertical movement of the support member 232 and to generate a downward reaction force. ing.
[0043]
On the other hand, the coiled portion of the torsion coil spring 241 is mounted coaxially with the rotational drive shaft 242 of the transport roller 24. One end of the torsion coil spring 241 is supported by the casing 200 of the automatic document feeder 20, and the other end is also supported by an elastic member fixed to the casing 200. A support member 232 is attached to the other end of the torsion coil spring 241, and the normal position of the pickup roller 23 is determined in a state where the urging force of the torsion coil spring 241 is released.
[0044]
Hereinafter, the operation of the paper feeding mechanism 21 will be described. When the document is placed at a predetermined position on the document table 22, the leading end of the document is positioned on the document pressing plate 26. When document feeding is started, the drive shaft 261 of the document pressing plate 26 is rotated to push the document pressing plate 26 upward so that the document bundle on the document pressing plate 26 is brought into contact with the pickup roller 23. At this time, in the automatic document feeder 20 of the prior art, it has been confirmed that a collision sound is generated by the upward driving of the document pressing plate 26.
[0045]
The vertical movement of the document pressing plate 26 is driven by a motor having a torque limiter disposed on the rotational drive shaft 261. When the document pressing plate 26 is driven upward by the motor, the pickup roller 23 is also pushed up together with the document bundle. Then, tension is generated in the torsion coil spring 241 and a reaction force that pushes down the pickup roller 23 is generated.
[0046]
On the other hand, the support member 232 that supports the pickup roller 23 is similarly pushed up by the document pressing plate 26. However, since the upper end of the free end of the support member 232 is in contact with the damper 231, the energy is absorbed by the damper 231. .
[0047]
When the reaction force generated by the torsion coil spring 241 and the damper 231 is balanced with the load torque of the torque limiter, the torque limiter disposed on the rotation drive shaft 261 of the document pressing plate 26 works, and the rotation drive shaft 261 of the document pressing plate 26 rotates idle. As a result, the impact force of the document pressing plate 26 is relaxed, and the document pressing plate 26 and the pickup roller 23 are balanced in a pressed state.
[0048]
At this time, a reaction force corresponding to the displacement of the rotation shaft of the pickup roller 23 caused by the pressing force of the document pressing plate 26 is generated by the torsion coil spring 241 and the damper 231 that are elastic members. The generated vibration of the pickup roller 23 can be converged in a short time to enhance the impact sound absorbing effect, and a stable paper feeding operation by the pickup roller 23 is also possible.
[0049]
In this embodiment, the automatic document feeder 20 connected to the copying machine is shown. However, the automatic document feeder 20 is connected to the image forming apparatus 10 such as a printer and a facsimile, a multifunction machine having a plurality of functions, a light printer, and the like. The same applies to the document conveying device used, and the same applies to the paper feeding device in the cassette paper feeding unit 50 of the image forming apparatus 10.
[0050]
【The invention's effect】
As described above, in the prior art in which the pickup roller is fixed to the casing, the pickup roller received the upward biasing force of the movable pressing plate at one point, and thus a large impact sound was generated. If the pickup roller is made movable as in the paper conveying device, energy due to the impact between the movable pressing plate and the pickup roller can be diffused, so that the impact sound can be reduced.
[0051]
In addition, the pickup roller is made movable, and the torsion coil spring and damper, which are elastic bodies for absorbing shock, are provided, so that the vibration of the pickup roller caused by the impact force of the movable pressing plate is rapidly converged to reduce the impact sound. The absorption effect can be enhanced, and not only a stable paper feeding operation can be performed, but also the reliability of the apparatus itself can be improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image forming apparatus equipped with an automatic document feeder according to an embodiment of the present invention.
FIG. 2 is an overall configuration diagram of an automatic document feeder according to an embodiment of the present invention.
FIG. 3 is a configuration diagram illustrating a paper feed mechanism including an impact absorbing mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming apparatus 20 Automatic document feeder 201,202 Switching gate 21 Paper feed mechanism 22 Document stand (paper stand)
23, 53 Pickup roller 231 Damper 24 Transport roller 24A Separation roller 241 Torsion coil spring 242 Support member 25A Registration drive roller 25B Registration driven roller 26 Document pressing plate (movable pressing plate)
28, 71 Paper discharge roller 29 Paper discharge table 30 Image reading part 35 Image processing part 40 Image forming part 50 Cassette paper feed part 60 Fixing device 70 Paper discharge part

Claims (3)

A movable press provided on a paper transport device on which a paper table on which a document, recording paper, etc. (hereinafter referred to as a document) is mounted is mounted, and urges the document loaded on the paper table upward. The board,
Opposed to the urging direction of the movable pressing plate, abuts against a document or the like urged above the sheet table by the movable pressing plate, and rotates to move the document or the like from the sheet table to a conveyance roller. A pick-up roller to send out;
In a paper transport device having
The pickup roller is attached to a support member pivotally supported by a rotation drive shaft of the transport roller, and is attached to a casing and a damper with which the tip of the support member abuts, and an elastic member that urges the support member to rotate. An impact absorbing mechanism is formed from the member, and the impact absorbing mechanism absorbs an impact when the movable pressing plate presses the document or the like loaded on the paper table against the pickup roller. Paper transport device.   2. The sheet conveying apparatus according to claim 1, wherein the elastic member is a torsion coil spring having a coil portion mounted coaxially with a rotation driving shaft of the conveying roller.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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