JP6552348B2 - Sheet feeding apparatus, image reading apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus for feeding a sheet, and an image reading apparatus and an image forming apparatus provided with the sheet feeding apparatus.

  Conventionally, an image forming apparatus such as a printer or an image reading apparatus mounted on a printer is provided with a sheet feeding apparatus for feeding sheets. Conventionally, this type of sheet feeding apparatus includes a pickup roller for feeding sheets stacked on a deck, and a feed roller and a retard roller for separating the fed sheets one by one. An apparatus has been proposed (see Patent Document 1). The retard roller is supported so as to be able to swing, and is in contact with the feed roller at a predetermined nip pressure.

  The retard roller receives a driving force in the direction opposite to the sheet conveyance direction, and acts as a conveyance resistance when the sheet is pulled out by the conveyance roller pair disposed downstream from the feed roller in the conveyance direction. . The sheet pulled by the pair of conveying rollers is conveyed in tension between the separation nip formed by the feed roller and the retard roller and the conveyance nip formed by the pair of conveyance rollers by the conveyance resistance.

JP 2000-191169 A

  When the retard roller is configured to be swingable as in the sheet feeding device described in Patent Document 1, depending on the position of the retard roller or the position of the conveying roller pair, the retard force may be caused by the frictional force of the tensioned sheet. The roller may be separated from the feed roller. When the retard roller separates from the feed roller, the subsequent sheet is transported past the separation nip, causing a problem that the sheet may jam.

  Further, as in the case of the sheet feeding device described in Patent Document 1, when the conveyance guide is disposed on a straight line connecting the separation nip and the conveyance nip, the sheet in a tensioned state is rubbed by the conveyance guide. Damage to the sheet will occur.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet feeding device, an image reading device, and an image forming device that reliably separate sheets and suppress damage to the sheets.

  The present invention relates to, in a sheet feeding apparatus, a stacking unit that stacks sheets, a feeding unit that feeds a sheet stacked on the stacking unit, and a first unit that transports a sheet fed by the feeding unit. A transporting unit, a separating unit which forms a separating nip together with the first transporting unit, and which separates the sheet one by one by the separating nip, and is disposed downstream of the separating nip in the sheet conveying direction to convey the sheet. Are disposed between the separation nip and the conveyance nip in the conveyance direction, and the second conveyance means and the third conveyance means for nipping and conveying by; the support means for rotatably supporting the separation means; And a rotary member coaxially supported with the rocking shaft and rotatably supported, the outer peripheral surface of the rotary member protruding into the sheet conveyance path. That.

  According to the present invention, since the rotation member is provided coaxially with the swinging axis of the support means, the positional accuracy between the separation means supported by the support means and the rotation member can be improved. Further, since the rotating member is provided with high positional accuracy so that the outer peripheral surface thereof protrudes into the transport path, it is possible to obtain the sheet feeding apparatus capable of reliably separating the sheets one by one and suppressing damage to the sheet. It is done.

FIG. 1 is an overall schematic view showing an image forming apparatus according to the present embodiment. The side view which shows the waiting position and scanning position of an optical box. The side view which shows a sheet feeding apparatus. FIG. The side view which shows a roller. The side view which shows the reference example which changed arrangement | positioning of the auxiliary | assistant roller.

  An image reading apparatus according to an embodiment of the present invention is provided in a copying machine, a printer, a facsimile, and a composite device thereof. In the present embodiment, the position at which the user faces the operation unit (not shown) for performing various inputs / settings on the image reading apparatus is referred to as the “front side” of the image reading apparatus, and the back side is “back side”. That's it. FIG. 1 shows an internal configuration of the image reading apparatus as viewed from the front side.

[overall structure]
The printer 1 (image forming apparatus) includes a printer main body 3 having an image forming unit 4 and a cassette feeding unit 5, and an image reading device 2 disposed above the printer main body 3. As shown in FIG. 1, the image reading device 2 includes a reader unit 20 that reads an image of a document (sheet), and an ADF 10 (Auto Document Feeder) that can transport the document to the reader unit 20. Further, in the image reading device 2, the ADF 10 is rotatably supported by the reader unit 20 by a hinge disposed on the back side so that the platen glass 203 described later can be opened and closed from the front side. . The ADF 10 may feed not only a document on which an image is formed but also a blank sheet, and any sheet may be fed as long as it is in a sheet form.

  The reader unit 20 includes an optical box 30 a for reading an image of a document, a platen glass 201, and a document table glass 203 disposed on the top surface of the reader unit 20 along with the platen glass 201. The optical box 30a (reading unit) includes a lamp 310 that irradiates a document, and mirrors 301, 302, and 303 that guide reflected light from the document. The optical box 30a also includes a lens 304 for condensing the reflected light induced by the mirrors 301, 302, 303, and a charge coupled device 305 (hereinafter referred to as “photoelectric conversion”) which photoelectrically converts the collected reflected light. And a CCD).

  The optical box 30a is connected to a wire (not shown), and is driven by a motor (not shown) to scan the reading position below the platen glass 201 (the position shown in FIG. 1) and scanning below the platen glass 203. It can be moved between the position (the position shown by the broken line in FIG. 2). The position of the optical box 30a can be grasped by a position sensor (not shown) and the number of rotation pulses of the motor. In addition, the optical box 30a is stopped at the reading position, and the form of reading the document moving on the platen glass 201 is scanned, the document is placed on the document table glass 203, and the standby position shown by the solid line in FIG. The form read while moving the optical box 30a is called fixed reading.

  The ADF 10 has a sheet feeding device 40, conveyance roller pairs 104, 106, 108, 110, a registration roller pair (hereinafter referred to as registration roller pair) 105, and platen rollers 107, 109. The ADF 10 includes a back platen glass 202, a back optical box 30b, a discharge roller pair 111, and a discharge tray 122.

  Next, an operation when the image reading device 2 reads an image will be described. When the control unit (not shown) receives the image reading signal of the flow reading, the document stacked on the document tray 409 (stacking unit) is fed by the sheet feeding device 40 described later. The front end of the fed document comes into contact with the registration roller pair 105 in a stopped state, and a loop is generated when the document is pushed by a predetermined amount by the conveying roller pair 104 in this state. Due to the stiffness of the document by this loop, the leading edge of the document follows the nip of the registration roller pair 105, and the skew of the document is corrected.

  Then, the document is resumed when the registration roller pair 105 is driven, and is conveyed while being pressed against the platen glass 201 by the platen roller 107. At this time, the optical box 30a is located at a reading position which is a position below the platen glass 201 as shown in FIG. The optical box 30 a irradiates light by the lamp 310 toward the document conveyed on the platen glass 201, and the CCD 305 reads the reflected light from the document through the mirrors 301, 302, 303 and the lens 304. The CCD 305 photoelectrically converts the reflected light and outputs it as an electronic image signal to a printer unit (not shown) or the like.

  A document whose front surface has been read by the optical box 30 a is conveyed toward the rear surface platen glass 202 by the conveyance roller pair 108, and is conveyed in a state of being pressed against the rear surface platen glass 202 by the platen roller 109. A document conveyed on the back platen glass 202 is scanned on the back side by the back side optical box 30b in the same manner as the front side. The original on which the front and back images are read is discharged to the discharge tray 122 by the transport roller pair 110 and the discharge roller pair 111.

  On the other hand, when reading an image of a document by fixed reading, the user opens the ADF 10 and places the document on the document table glass 203. Then, the user positions the document on the document platen glass 203 by closing the ADF 10. When the control unit receives an image reading signal for fixed reading in this state, the optical box 30a reads the image of the document while moving in the X direction from the standby position indicated by the solid line to the scanning position indicated by the broken line in FIG.

  The image data of the document read by the image reading device 2 is, for example, formed on the sheet fed from the cassette feeding unit 5 of the printer main body 3 by the image forming unit 4 (image forming unit). The sheet on which the image is formed by the image forming unit 4 is fixed by an unillustrated fixing device, and is discharged outside the apparatus.

[Sheet feeding device]
Next, the sheet feeding apparatus 40 will be described in detail. As shown in FIG. 3, the sheet feeding apparatus 40 includes an original tray 409, a pickup roller 401 (feeding means), a feed roller 402 (first conveying means), and a separating roller 403 (separating means). Have. Further, the sheet feeding device 40 includes a drawing roller 407 (second conveying unit), a drawing roller 406 (third conveying unit), a pre-separation unit 415 (inclined surface), and a separating roller holder 404 (support unit). ,have.

  The pickup roller 401 is held by a feed arm 408 rotatably supported around a rotation shaft 402 a of the feed roller 402, and feeds an original stacked on an original tray 409. The feeding arm 408 is configured to rotate according to the height of the uppermost document stacked on the document tray 409.

  The separating roller 403 forms a separation nip N1 together with the feed roller 402, and separates the sheets one by one by the separation nip N1. The drawing roller 407 and the drawing roller 406 are disposed downstream of the separation nip N1 in the document conveyance direction, and nip and convey the document by the conveyance nip N2. A drive force can be input to the drawing roller 407 so as to convey the document in the conveyance direction (forward direction), and the drawing roller 406 rotates together with the drawing roller 407.

  The pre-separation unit 415 is disposed upstream of the separation nip N1 in the transport direction and is formed to be inclined upward toward the downstream. The pre-separating portion 415 protrudes from below into the document transport path 50, and the tip end 415a on the downstream side of the pre-separating portion 415 in the transport direction is slightly exposed to rubber.

  The document fed from the document tray 409 by the pickup roller 401 is guided while being in sliding contact with the pre-separation unit 415. However, since the pre-separation unit 415 has an upward slope, the lower the document, the higher the conveyance load. Becomes larger. Further, the rubber at the tip end 415a prevents the passage of documents other than the topmost document, and it is possible not to go over the pre-separation part 415 except for a few documents counted from the top. By such an operation, it is possible to prevent an excessive number of documents from being fed to the separation nip N1, and it is possible to reliably separate the documents one by one by the separation nip N1.

  When the leading end of the document separated into one sheet after passing through the pre-separation unit 415 and the separation nip N1 enters the transport nip N2, rotation of the drawing roller 407 is started, and the document is transported downstream by the transport nip N2 The Further, when the rotation of the pulling roller 407 is started, the pickup roller 401 and the feed roller 402 are turned off, and the pickup roller 401 and the feed roller 402 that are turned off are idled by a one-way clutch (not shown).

[Peripheral configuration of winding roller]
Next, the peripheral configuration of the rolling roller 403 will be described. As shown in FIGS. 3 to 5, the holder rotation shaft 413 (swing shaft) is disposed downstream of the separation nip N1 in the transport direction, and the holder rotation shaft 413 is fixed to the frame of the ADF 10 It is fixed by a rotating shaft support member 414. A whirling roller holder 404 is swingably supported on the holder rotation shaft 413, and the whirling roller holder 404 rotatably supports the whirling roller shaft 412 (roller shaft) of the whirling roller 403. The holder rotation shaft 413 is formed of metal.

  The separating roller holder 404 is biased toward the feed roller 402 by a tension spring 411 as shown in FIGS. 4 and 5, and the separating roller 403 is in contact with the feed roller 402 at a predetermined nip pressure. . A torque limiter 410 is interposed between the separating roller shaft 412 and the separating roller 403.

  The torque limiter 410 is configured to rotate along with the feed roller 402 at a predetermined torque or more, and to stop the rotation when the torque is less than the predetermined torque to hold a document. Basically, the surface friction resistance values of the tension spring 411 and the winding roller 403 are adjusted so that no torque exceeding a predetermined torque is generated during the conveyance of the document, and the rotation of the winding roller 403 is fixed. Thereby, in the separation nip N1, other than the uppermost document is blocked, and the documents can be separated one by one.

  Further, when the document is transported, torque is continuously applied to the torque limiter 410. Therefore, there are cases where the torque limiter 410 exceeds the predetermined torque value suddenly and instantaneously while a large number of documents are being fed. As a result, when the loosening roller 403 is slightly rotated as needed, a fresh roller surface is always exposed on the document conveyance surface, and high durability of separation performance can be achieved.

  An original document guide 404a is formed on the upper surface of the separating roller holder 404, and the conveyance path 50 includes an original document guide 404a and an upper surface guide 51 facing the original document guide 404a between the separation nip N1 and the conveyance nip N2. The second guide is configured. The document guide 404a (first guide) is curved in a convex shape toward the conveyance path 50 side (upper side), and this curved shape ensures that the leading edge of the document is fed into the conveyance nip N2 by the feed roller 402. It is a necessary configuration.

  This is because the pre-separation unit 415 has the document transport direction upward, so that the nip line B of the separation nip N1 is also inclined so that the downstream in the transport direction is higher than the upstream. It is because it is doing.

  As described above, when the leading end of the document enters the conveyance nip N2, the drawing roller 407 starts to rotate, and the drive of the pickup roller 401 and the feed roller 402 is cut off and idles. Further, since the rotation of the loosening roller 403 is fixed, the separation nip N1 serves as a conveyance resistance. Therefore, the document is pulled between the separation nip N1 and the conveyance nip N2, and is in a tension state.

  Here, as shown in FIG. 3, the document guide 404a overlaps with a straight line A connecting the separation nip N1 and the conveyance nip N2. Therefore, in the present embodiment, the document in the tension state is rotatably supported coaxially with the holder rotation shaft 413 in order to suppress the rubbing of the document guide 404 a with the document guide 404 a, and the outer peripheral surface 405 a is Auxiliary rollers 405, 405 are provided to project in the conveyance path 50. The auxiliary roller 405 (rotating member) is a resin roller formed of a resin such as polyacetal (POM), for example, and its outer peripheral surface 405a protrudes from the straight line A toward the feed roller 402 side (first conveying means side). Is provided. Further, the outer peripheral surface 405 a of the auxiliary roller 405 is provided so as to intersect the document guide 404 a on a plane orthogonal to the axial direction of the holder rotation shaft 413.

  Therefore, when the document is conveyed between the separation nip N1 and the conveyance nip N2, the document abuts on the outer peripheral surface 405a of the auxiliary roller 405, and the auxiliary roller 405 rotates along with the document. Thereby, it is possible to suppress the formation of damage such as a rubbing trace on the document and to convey the document smoothly.

  Further, as shown in FIG. 3, the auxiliary roller 405 is provided such that the outer peripheral surface thereof protrudes toward the feed roller 402 beyond the nip line B, and when the document is pulled out by the transport nip N2, This prevents 403 from being pressed.

  Here, a case where the auxiliary roller 505 is disposed on the side of the roller that is spaced from the nip line B as in the reference example shown in FIG. As shown in FIG. 6, the document P pulled between the auxiliary roller 505 and the separation nip N1 has a frictional force μN acting on the separation nip N1. At this time, since the component force F of the frictional force μN acts in a direction to push the roller 403 down, the roller roller holder 404 rotates downward against the urging force of the tension spring 411.

  When the separating roller 403 separates from the feed roller 402 in this manner, the originals can not be separated one by one, and a plurality of originals simultaneously pass between the feed roller 402 and the separating roller 403, causing a jam. It becomes. In the present embodiment, as described above, since the outer peripheral surface of the auxiliary roller 405 is provided so as to protrude toward the feed roller 402 from the nip line B, the force for pushing down the separating roller 403 does not act, and the document Can be reliably separated.

  Further, if the amount of protrusion of the auxiliary roller 405 to the conveyance path 50 is insufficient, the above effect can not be obtained, and if the amount of protrusion is too large, the document may be curled. For this reason, the positional accuracy between the auxiliary roller 405 and the whirling roller 403 is important, but in this embodiment, the auxiliary roller 405 is provided on the holder rotation shaft 413 that is the center of swinging of the whirling roller 403. As a result, the number of parts interposed between the auxiliary roller 405 and the loosening roller 403 can be reduced, and the positional accuracy between the auxiliary roller 405 and the loosening roller 403 can be improved.

  Further, since the holder rotation shaft 413 is made of metal and the auxiliary roller 405 is made of resin, the sliding sound generated between the holder rotation shaft 413 and the auxiliary roller 405 is reduced. Can do.

  Although the sheet feeding device 40 is applied to the ADF 10 in the present embodiment, the sheet feeding device 40 may be applied to, for example, the cassette feeding portion 5 of the printer main body 3 or a multi feeding portion (not shown).

  In the present embodiment, the auxiliary roller 405 and the holder rotation shaft 413 are configured separately, but may be configured to be integrally formed. Further, the auxiliary roller 405 is not limited to a roller, and may be composed of another rotating member such as a belt. In the present embodiment, the pre-separation unit 415 is provided upstream of the separation nip N1 in the transport direction, but a configuration in which the pre-separation unit 415 is not provided may be used.

  1: Image forming apparatus (printer) / 2: image reading device / 4: image forming means (image forming unit) / 30a: reading unit (optical box) / 40: sheet feeding device / 50: conveyance path / 51: fifth 2 Guide (upper surface guide) / 401: feeding means (pickup roller) / 402: first conveying means (feed roller) / 403: separating means (separating roller) / 404: supporting means (separating roller holder) / 404a: first 1 guide (original guide) / 405: rotating member (auxiliary roller) / 405a: outer peripheral surface / 406: third conveying means (extraction roller) / 407: second conveying means (extraction roller) / 409: stacking means (original tray) ) / 410: Torque limiter / 412: Roller shaft (rolling roller shaft) / 413: Oscillating shaft (holder rotating shaft) / 415: Inclined surface (pre-separation part) / A: Straight line / B: Nip line / N1: Away nip / N2: conveying nip

Claims (10)

Loading means for loading sheets;
A feeding means for feeding sheets stacked on the stacking means;
First conveying means for conveying the sheet fed by the feeding means;
Separating means for forming a separation nip together with the first conveying means, and separating the sheets one by one by the separation nip;
A second conveying means and a third conveying means which are arranged downstream of the separation nip in the conveying direction of the sheet and which sandwich and convey the sheet by the conveying nip;
Supporting means for rotatably supporting the separating means;
A swing shaft disposed between the separation nip and the transport nip in the transport direction and configured to swingably support the support means;
A rotating member that is rotatably supported on the same axis as the swing shaft, and whose outer peripheral surface protrudes into the sheet conveyance path,
Sheet feeding apparatus characterized in that. The outer peripheral surface of the rotating member protrudes toward the first conveying means from a straight line connecting the separation nip and the conveying nip.
The sheet feeding apparatus according to claim 1. The outer peripheral surface of the rotating member protrudes toward the first conveying means from the nip line of the separation nip;
The sheet feeding apparatus according to claim 1 or 2, wherein The transport path is formed by a first guide formed on an upper surface of the support means, and a second guide facing the first guide,
The outer peripheral surface of the rotating member intersects the first guide in a plane orthogonal to the axial direction of the swing shaft;
The sheet feeding device according to any one of claims 1 to 3, wherein the sheet feeding device is provided. In addition to being disposed upstream of the separation nip in the conveying direction, the inclined surface is formed to be inclined upward toward the downstream, and is in sliding contact with the sheet fed by the feeding unit.
The sheet feeding device according to any one of claims 1 to 4, wherein the sheet feeding device is provided. The nip line of the separation nip is formed so as to be inclined so that the downstream in the transport direction is higher than the upstream.
The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. The separating means is a roller,
A roller shaft supported by the support means;
A torque limiter interposed between the roller shaft and the roller,
The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device. The rotating member is a resin roller formed of resin,
The swing shaft is made of metal.
The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device. A sheet feeding device according to any one of claims 1 to 8,
A reading unit that reads an image of the sheet fed by the sheet feeding device,
An image reading apparatus characterized in that. A sheet feeding device according to any one of claims 1 to 8,
Image forming means for forming an image on the sheet fed by the sheet feeding device,
An image forming apparatus.

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