US20080211166A1 - Sheet feeding device and image forming apparatus - Google Patents

Sheet feeding device and image forming apparatus Download PDF

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Publication number
US20080211166A1
US20080211166A1 US12/036,617 US3661708A US2008211166A1 US 20080211166 A1 US20080211166 A1 US 20080211166A1 US 3661708 A US3661708 A US 3661708A US 2008211166 A1 US2008211166 A1 US 2008211166A1
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US
United States
Prior art keywords
sheet
separating member
guide member
roller
feed roller
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/036,617
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English (en)
Inventor
Yuta Kawaguchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Assigned to CANON KABUSHIKI KAISHA reassignment CANON KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAWAGUCHI, YUTA
Publication of US20080211166A1 publication Critical patent/US20080211166A1/en
Abandoned legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H5/00—Feeding articles separated from piles; Feeding articles to machines
    • B65H5/36—Article guides or smoothers, e.g. movable in operation
    • B65H5/38—Article guides or smoothers, e.g. movable in operation immovable in operation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H3/00—Separating articles from piles
    • B65H3/46—Supplementary devices or measures to assist separation or prevent double feed
    • B65H3/52—Friction retainers acting on under or rear side of article being separated
    • B65H3/5207—Non-driven retainers, e.g. movable retainers being moved by the motion of the article
    • B65H3/5215—Non-driven retainers, e.g. movable retainers being moved by the motion of the article the retainers positioned under articles separated from the top of the pile
    • B65H3/5223—Retainers of the pad-type, e.g. friction pads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/30—Orientation, displacement, position of the handled material
    • B65H2301/31—Features of transport path
    • B65H2301/312—Features of transport path for transport path involving at least two planes of transport forming an angle between each other
    • B65H2301/3121—L-shaped
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2301/00—Handling processes for sheets or webs
    • B65H2301/30—Orientation, displacement, position of the handled material
    • B65H2301/34—Modifying, selecting, changing direction of displacement
    • B65H2301/342—Modifying, selecting, changing direction of displacement with change of plane of displacement

Definitions

  • the present invention relates to a sheet feeding device which separates multi-feeding sheets one by one to feed the sheet to an image forming portion on a downstream side, particularly to a structure in which vibration and noise are prevented when the sheet is drawn from the downstream side after feeding of the sheet is stopped.
  • a sheet feeding device in which the sheet passes between a feed roller and a friction separating member pressure-contacting each other and the sheet is separated one by one and fed to the image forming portion on the downstream side.
  • Japanese patent Application Laid-Open No. 2004-26403 discloses a sheet feeding device, in which the sheet separated and fed by the feed roller and the friction separating member is conveyed to a pair of conveying rollers of the image forming portion and the sheet is conveyed while nipped between the pair of conveying rollers.
  • the feed roller is partially cut out, i.e., the feed roller is formed in a so-called crescent shape, and a pressing roller is provided coaxially with the sheet feeding roller.
  • the sheet is nipped between the friction separating member and the rotatable pressing roller instead of the feed roller having large friction, which prevent the multi feed of the sheet.
  • Japanese patent Application Laid-Open No. 7-133033 discloses a sheet feeding device in which the sheet is guided while a course of the sheet fed by the feed roller is largely bent toward the feed roller side (so as to wound around the feed roller).
  • the friction separating member is fixed to a loosely-journaled lever arm, and a pressing spring applies a force to the lever arm to cause the friction separating member to pressure-contact the feed roller.
  • a vibration insulating spring is attached to the lever arm to prevent vibration (noise generation). The vibration is caused by rattling the lever arm around a rotating shaft in drawing the sheet.
  • Japanese patent Application Laid-Open No. 5-208747 discloses a sheet feeding device, in which a solenoid is provided to move up and down the lever arm to which the friction separating member is fixed. In this case, when the sheet reaches a conveying roller on the downstream side, the solenoid is started up to release the pressure contact between the feed roller and the friction separating member, which reduces the generation of the vibration (noise). The vibration is generated by resistance when the conveying roller draws the sheet and by the rattle around the lever arm.
  • the invention provides a sheet feeding device in which the vibration and noise can largely be reduced in the rotating shaft of the feed roller while the friction separating member sufficiently exerts the function of preventing the multi feed.
  • a sheet feeding device includes a sheet feed member which feeds a sheet; a separating member which separates the sheet between the sheet feed member and the separating member; a first guide member which guides the sheet fed by the sheet feed member while bending the sheet toward a sheet feed member side; a sheet conveying unit which conveys the sheet guided by the first guide member while nipping the sheet; and a second guide member which orientates a course of the sheet toward a sheet conveying unit side, wherein the second guide member contacts a surface on the sheet feed member side of the sheet drawn between the sheet feed member and the separating member, on a tangent line of the sheet feed member at a position where the sheet feed member contacts the separating member, or at a position located on a separating member side in relation to the tangent line.
  • the sheet conveying unit draws the sheet from the nip between the sheet pressing member and the separating member.
  • the direction in which the sheet is drawn between the sheet feed member and the separating member is located on the separating member side of the tangent line or on the tangent line of the sheet feed member located at the position where the second guide member pressure-contact the separating member. Therefore, the force in the direction in which the separating member is separated from the sheet feed member is applied to the separating member from the conveyed sheet, and the force of the pressure contact between the separating member and the pressing member is weakened, so that the generation of the vibration can be reduced in the sheet feed member.
  • FIG. 1 is an explanatory view of a configuration of an image forming apparatus according to an embodiment of the invention.
  • FIG. 2 is a perspective view of a sheet stacking member of a sheet feeding device.
  • FIG. 3 is an explanatory view of assembly of a feed roller.
  • FIG. 4 is an explanatory view of assembly of a separating member.
  • FIG. 5 is an explanatory view of a configuration of a sheet feeding device according to a first embodiment of the invention.
  • FIG. 6 is an explanatory view of operation of a second sheet guide member of the sheet feeding device.
  • FIG. 7 is an explanatory view of a sheet feeding device according to a comparative example in which the second sheet guide member is eliminated.
  • FIG. 8 is an explanatory view of a configuration of a sheet feeding device according to a second embodiment of the invention.
  • FIG. 9 is an explanatory view of operation of a second sheet guide member of the sheet feeding device.
  • FIG. 10 is an explanatory view of a configuration of a sheet feeding device according to a third embodiment of the invention.
  • FIG. 11 is an explanatory view of operation of a second sheet guide member of the sheet feeding device.
  • a sheet feeding device of the invention can be mounted on not only an image forming apparatus but also various kinds of sheet processing apparatus and sheet processing apparatus including an image reading apparatus.
  • An image forming apparatus of the invention can be implemented in not only a monochrome printer but also various applications such as an electrophotographic full-color printer, a copying machine, FAX, and a multifunction peripheral.
  • the image forming apparatus of the invention can be implemented in not only the electrophotographic system but also various printing methods in which images are formed in various sheet materials.
  • FIG. 1 is an explanatory view of a configuration of an image forming apparatus according to an embodiment of the invention.
  • An image forming apparatus 14 is an electrophotographic monochrome printer.
  • a sheet feeding device 1 is disposed in a lower portion of an apparatus main body.
  • sheets P stacked on a sheet stacking member 13 are separated one by one by a sheet feed member and a separating member 17 and the sheet P is fed to a direction of a pair of conveying rollers 21 .
  • the sheet feed member includes a feed roller 15 and a pressing roller 16 .
  • the feed roller 15 is formed in the so-called crescent roller in which a part of an outer periphery is partially cut out.
  • the feed roller 15 feeds the sheet P by contacting an upper surface of the sheet P stacked on the sheet stacking member 13 .
  • the feed roller 15 is rotated by one-rotation control using a driving mechanism (not illustrated), and the cut-out portion is rotated once from a position where the cut-out portion faces the separating member 17 , thereby feeding the sheet P.
  • the separating member 17 separates the sheet P one by one while nipping the sheet P between the separating member 17 and the feed roller 15 .
  • a pad arm 17 b and a pressing spring 18 are of an example of a support mechanism supporting the separating member 17 .
  • the pad arm 17 b and pressing spring 18 support the separating member 17 while applying a force to the separating member 17 toward the feed roller 15 .
  • a first sheet guide member 22 which is of an example of the first guide member guides the sheet P while bending a course of the sheet P fed by the feed roller 15 toward the side of the feed roller 15 .
  • a pair of conveying rollers 21 which is of an example of the sheet conveying unit conveys the sheet P while nipping the sheet P guided to the first sheet guide member 22 .
  • a pressing roller 16 which is of an example of the pressing member is provided to pressure-contact the separating member 17 when the cut-out portion of the feed roller 15 faces the separating member 17 .
  • the pressing roller 16 is a rotating body which is driven according to the sheet drawn by the pair of conveying rollers 21 while rotatably supported by a feed roller shaft 101 of the feed roller 15 .
  • a second sheet guide member 23 which is of an example of the second guide member contacts a surface on the side (the side contacted by the pressing roller) of the pressing roller 16 which is of an example of the pressing member side of the sheet P fed by the feed roller 15 and the separating member 17 .
  • the second sheet guide member 23 orientates the course of the sheet P toward the side of the pair of conveying rollers 21 which is of an example of the sheet conveying unit side.
  • the second sheet guide member 23 orientates the course of the sheet P toward the pair of conveying rollers 21 on the side of the separating member 17 with respect to a tangent line of the pressing roller 16 at the position (nip portion) where the second sheet guide member 23 pressure-contacts the separating member 17 . Therefore, although described in detail, the second sheet guide member 23 eliminates or decreases the nipping direction force applied on the pressing roller 16 in association with the sheet conveyance performed by the pair of conveying rollers 21 .
  • the sheet stacking member 13 which is of an example of a sheet accommodating unit retains the sheets P in the stacked state, and the feed roller 15 draws the top-most sheet P while contacting the top-most sheet P retained by the sheet stacking member 13 .
  • the top-most sheet P stacked on the sheet stacking member 13 is drawn by the feed roller 15 , and the sheets P are separated one by one in an abutment portion between the feed roller 15 and the separating member 17 .
  • the sheet P fed by the feed roller 15 is guided by the first sheet guide member 22 and transferred to the pair of conveying rollers (registration roller) 21 .
  • the pair of conveying rollers 21 includes a conveying roller 19 and a conveying roller 20 , and the pair of conveying rollers 21 feeds the sheet P to a transfer nip between a photosensitive drum 2 and a transfer roller 6 in synchronization with a head of a toner image formed in the photosensitive drum 2 .
  • a charging roller 3 , an exposing device 7 , a development portion 5 , the transfer roller 6 , and a cleaning portion 27 are disposed around the photosensitive drum 2 in an image forming portion G.
  • the photosensitive drum 2 , the charging roller 3 , the development portion 5 , and the cleaning portion 27 are assembled in a cartridge and drawn toward a near side to be able to be exchanged.
  • the cleaning portion 27 cleans a surface of the photosensitive drum 2 , and the charging roller 3 evenly charges the surface of the photosensitive drum 2 .
  • the charged surface of the photosensitive drum 2 is scanned to write an electrostatic image with a laser beam modulated by an image signal to write an electrostatic image.
  • the development portion 5 causes toner to adhere to the electrostatic image on the photosensitive drum 2 to form a toner image while a development sleeve 4 bears the toner stored in a toner container.
  • a transfer voltage having an opposite polarity to a polarity in which the toner image is charged is applied to the transfer roller 6 to transfer the toner image from the photosensitive drum 2 to the sheet P fed to the transfer nip.
  • the sheet P to which the toner image is transferred is fed to a fixing device 10 , and the sheet P is conveyed while nipped in a fixing nip between a pressure roller 9 and a heating device 8 , thereby fixing the toner image to the surface of the sheet P.
  • the sheet P to which the toner image is fixed is conveyed while nipped between a discharge roller 11 and a discharge roller 12 , and the sheet P is discharged to a discharge tray 26 .
  • FIG. 2 is a perspective view of a sheet stacking member of the sheet feeding device
  • FIG. 3 is an explanatory view of assembly of the feed roller
  • FIG. 4 is an explanatory view of assembly of the separating member.
  • the first sheet guide member 22 constitutes a part of a frame body of the resin-molded sheet feeding device 1 .
  • An intermediate-plate support plate 122 is fixed to the sheet stacking member 13 , and an intermediate plate 120 is rotatably supported by an intermediate plate shaft 121 supported with an intermediate-plate support plate 122 .
  • Pressing springs 123 are disposed between the intermediate plate 120 and the sheet stacking member 13 , and the pressing springs 123 upwardly apply a force to the sheet placed on the intermediate plate 120 to cause the sheet to pressure-contact a feed roller shaft unit 40 .
  • a feed roller shaft 101 is rotatably supported by a sidewall of the sheet stacking member 13 , and symmetrical intermediate plate cams 106 and 107 are fixed to both end portions of the feed roller shaft 101 .
  • the intermediate plate cams 106 and 107 are rotated while being integral with the feed roller shaft 101 , and the intermediate plate cams 106 and 107 push down the intermediate plate 120 against the pressing springs 123 to separate the sheet placed on the intermediate plate 120 from the feed roller shaft unit 40 .
  • a feed gear 108 is fixed to the outside of the intermediate plate cam 106 , and selective rotation is transmitted to the feed gear 108 by a solenoid or a clutch (not illustrated).
  • the feed roller shaft unit 40 is fixed to the feed roller shaft 101 , and a separating member unit 41 is disposed below the feed roller shaft unit 40 .
  • a feed roller holder 102 is fixed in a substantially central portion of the feed roller shaft 101 .
  • the feed roller holder 102 is integrally molded using a resin, an facing interval is widened to detachably attached a feed roller collar 103 by pushing down knobs 102 c provided both side faces of the feed roller holder 102 .
  • the feed roller 15 is made of an elastic material such as EPDM and an elastomer which has a high friction coefficient.
  • the feed roller 15 is assembled by enclosing the outside of the half-round feed roller collar 103 .
  • two index bosses 103 a provided in side faces of the feed roller collar 103 engage U-shape grooves 102 a provided in the side faces of the feed roller holder 102 .
  • pawls 103 b provided in the side faces of the feed roller collar 103 engages holes 102 b made in the side faces of the feed roller holder 102 .
  • the feed roller 15 is assembled by pressing a saddle portion 104 a against the feed roller shaft 101 .
  • the pressing force pulls the outside of the feed roller 15 in a circumferential direction to wind the feed roller 15 around the outer periphery of the feed roller collar 103 with no gap.
  • the pressing rollers 16 are rotatably supported on the sides of a hollow sleeve orientated toward the outside of the feed roller holder 102 , and pressing roller regulating portions 102 d prevent drop-off of the pressing rollers 16 .
  • the separating member 17 is made of a rubber material such as EPDM and elastomer, and the separating member 17 is bonded to a pad arm 17 b.
  • a boss extended from a swing support 17 a is fitted in an arm retaining portion 17 d provided in a pad holder 17 e, which rotatably retains the pad arm 17 b.
  • the pressing spring 18 is disposed between the pad arm 17 b and the pad holder 17 e, and the pressing spring 18 generates an applying force toward an obliquely upward direction such that the separating member 17 pressure-contacts the feed roller 15 or pressing roller 16 of FIG. 3 .
  • ⁇ 1 is a friction coefficient between the feed roller 15 and the sheet P
  • ⁇ 3 is a friction coefficient between the two sheets P overlapping each other
  • ⁇ 2 is a friction coefficient between the sheet P and the separating member 17 .
  • the friction coefficient ⁇ 1 of the feed roller 15 and the friction coefficient ⁇ 2 of the separating member 17 are set such that a relationship of an expression (1) is satisfied.
  • a force FS 1 applied to the first sheet P 1 is computed as follows.
  • F 1 is the conveying force receiving from the feed roller 15 and F 3 is a drag receiving from the second sheet P.
  • the sheet feeding device 1 the sheet P is separated one by one and fed using the feed roller 15 . Then, the sheet P is drawn from the nip between the pressing roller 16 and the separating member 17 without generating the multi feed.
  • FIG. 5 is an explanatory view of a configuration of a sheet feeding device according to a first embodiment of the invention
  • FIG. 6 is an explanatory view of operation of a second sheet guide member of the sheet feeding device
  • FIG. 7 is an explanatory view of a sheet feeding device according to a comparative example in which the second sheet guide member is eliminated.
  • a sheet feeding device 1 A of the comparative example has the same configuration as the first embodiment illustrated by FIGS. 1 and 2 except that the second sheet guide member 23 ( FIG. 6 ) is eliminated. Therefore, the same component of FIG. 7 is designated by the same numeral of FIG. 6 , and the overlapping description is neglected.
  • the feed roller 15 is rotated and the top-most sheet P of the sheet stacking member 13 is fed while frictioned with the separating member 17 .
  • the sheet P fed by the feed roller 15 is separated one by one by the separating member 17 which is pressed against the feed roller 15 by the pressing spring 18 .
  • the surface friction coefficient, contact angle, and shape of the separating member 17 are adjusted such that only one top-most sheet P is conveyed in each feed operation.
  • the fed sheet P is guided to the first sheet guide member 22 to bend the course of the sheet P upward, and the sheet P is transferred to the pair of conveying rollers 21 .
  • the pair of conveying rollers 21 conveys the transferred sheet P while nipping the sheet P therebetween.
  • the feed roller 15 is rotated once to stop the sheet feeding operation, and the cut-out portion of the feed roller 15 faces the separating member 17 . Therefore, the sheet P is nipped between the pressing roller 16 and the separating member 17 .
  • the pressing roller 16 is driven according to the sheet P drawn by the pair of conveying rollers 21 . Similarly to the feed roller 15 , the pressing roller 16 continuously presses the sheet P against the separating member 17 , the second sheet multi-fed along with the first sheet P is blocked by the separating member 17 .
  • the pair of conveying rollers 21 is provided toward the side of the pressing roller 16 (the side on which the pressing roller 16 is disposed in relation to a tangent line A) from the tangent line A of the pressing roller 16 in the pressure-contact portion (nip portion) between the pressing roller 16 and the separating member 17 .
  • the first sheet guide member 22 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the first sheet guide member 22 guides the sheet (P), fed to the feed roller 15 , on the side of the separating member 17 .
  • the second sheet guide member 23 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the second sheet guide member 23 guides the sheet (P), fed to the feed roller 15 , on the side of the pressing roller 16 .
  • a projection 23 a is formed in the second sheet guide member 23 , and the projection 23 a is disposed on the tangent line A or at the position where the projection 23 a is projected toward the side of the separating member 17 from the tangent line A (the side on which the separating member 17 is disposed in relation to a tangent line A).
  • the projection 23 a ensures a gap with the first sheet guide member 22 to form a sheet conveying passage.
  • the sheet (P) fed to the feed roller 15 is fed to the pair of conveying rollers 21 through a space between the first sheet guide member 22 and the second sheet guide member 23 .
  • the pressing roller 16 pressure-contacts the separating member 17 to prevent the multi feed of the sheet (P) after the sheet feeding operation is performed by the feed roller 15 .
  • the sheet (P) is conveyed to the downstream by the pair of conveying rollers 21 so as to be drawn while nipped between the separating member 17 and the pressing roller 16 .
  • the coupling line B 1 is a line coupling the abutment portion between the pressing roller 16 and the separating member 17 and a point at which the sheet (P) contacts the conveying roller 19 .
  • the tension F 1 in the direction of the coupling line B 1 can be divided into a force Ft 1 in a direction of the tangent line A and a force Fn 1 applied to the pressing roller 16 toward a center 16 a.
  • the sheet (P) is drawn from the nip between the separating member 17 and the pressing roller 16 while generating a force pressing the pressing roller 16 toward the center 16 a. Therefore, the pressing roller 16 is vibrated to generate the noise according to the fluctuation in tension of the sheet (P).
  • the projection 23 a of the second sheet guide member 23 is projected toward the side of the separating member 17 from tangent line A, and the gap is ensured between the projection 23 a and the first sheet guide member 22 . Therefore, the direction in which the sheet (P) is drawn becomes a direction of a coupling line B 2 , when the pair of conveying rollers 21 conveys the sheet (P) toward the downstream side to draw the sheet (P) from the nip between the pressing roller 16 and the separating member 17 .
  • the coupling line B 2 is a line drawn from the pressure-contact portion between the pressing roller 16 and the separating member 17 to the projection 23 a of the second sheet guide member 23 .
  • the vibration and noise can be suppressed on the downstream side distant from the structure separating the sheet irrespective of the addition of the member around the separating member or the change in pressure-contact state. Therefore, the change in configuration does not have an influence on the separation feed performance.
  • the generation of the force in the direction in which the separating member is pressed against the pressing roller by the drawing of the sheet, which is of the noise factor, is eliminated to reduce the noise with no influence on the separation feed performance.
  • a part of the second sheet guide member is projected on the tangent line drawn to the abutment surface of the pressing roller in the abutment portion (nip portion) between the pressing roller and the separating member or toward the separating member side from the tangent line.
  • the part of the second sheet guide member is provided between the first sheet guide member and the second sheet guide member.
  • the sheet drawing direction becomes the tangent line direction or the direction located on the separating member side in relation to the tangent line (direction inclined from the tangent line toward the side on which the separating member is disposed based on the abutment portion), and the force with which the separating member is pressed against the pressing roller by the drawing the sheet is eliminated or reduced, so that the generation of the noise can be reduced when the pair of conveying rollers conveys the sheet while the sheet is nipped between the separating member and the pressing roller. Even if the pressing force of the pressing roller is decreased, the sheet continuously presses the separating member with the tension. Therefore, the sheet intruding between the sheet and the separating member is blocked to avoid the multi feed of the sheet by the separating member.
  • FIG. 8 is an explanatory view of a configuration of a sheet feeding device according to a second embodiment of the invention
  • FIG. 9 is an explanatory view of operation of a second sheet guide member of the sheet feeding device.
  • a sheet feeding device 1 B of the second embodiment has the same configuration as the first embodiment except that the second sheet guide member 23 is replaced with a second sheet guide member 24 . Therefore, the same component of FIGS. 8 and 9 is designated by the same numeral of FIG. 6 , and the overlapping description is not presented.
  • the sheet feeding device 1 B of the second embodiment includes the sheet stacking member 13 , the feed roller 15 , the pressing roller 16 , the separating member 17 , the pressing spring 18 , and the pair of conveying rollers 21 .
  • the feed roller 15 is provided integrally or detachably.
  • the pressing roller 16 abuts on the separating member 17 to prevent the multi feed of the sheet P after the feed roller 15 is operated.
  • the separating member 17 is swingably supported by the swing support 17 a located on the upstream side in the conveying direction of the separating member 17 .
  • the sheet P placed on the sheet stacking member 13 is fed by the feed roller 15 and separated one by one by the separating member 17 .
  • the separating member 17 is pressed against the feed roller 15 by the pressing spring 18 .
  • the surface friction coefficient, contact angle, and shape of the separating member 17 are adjusted such that only one top-most sheet P is conveyed in each feed operation.
  • the separating member 17 is pressed against the pressing roller 16 to nip the sheet P therebetween.
  • the sheet P is fed to the pair of conveying rollers 21 while guided by the first sheet guide member 22 and the second sheet guide member 24 . Then, the sheet P is conveyed toward the downstream side by the pair of conveying rollers 21 so as to be drawn while nipped between the separating member 17 and the pressing roller 16 .
  • the pair of conveying rollers 21 is provided on the side of the pressing roller 16 from the tangent line A of the pressing roller 16 in the abutment portion between the pressing roller 16 and the separating member 17 (the side on which the separating member 17 is disposed in relation to a tangent line A).
  • the first sheet guide member 22 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the first sheet guide member 22 guides the sheet (P), fed to the feed roller 15 , on the side of the separating member 17 .
  • a second sheet guide member 24 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the second sheet guide member 24 guides the sheet (P), sent to the feed roller 15 , on the side of the pressing roller 16 .
  • a projection 24 a is formed in the second sheet guide member 24 , and the projection 24 a is disposed on the tangent line A or at the position where the projection 24 a is projected toward the side of the separating member 17 from the tangent line A.
  • the projection 24 a ensures a gap with the first sheet guide member 22 .
  • the pair of conveying rollers 21 which is of an example of the sheet conveying unit and the second sheet guide member 24 which is of an example of the second guide member are exchangeably assembled integral with each other while a positional relationship is fixed between the pair of conveying rollers 21 and the second sheet guide member 24 .
  • the second sheet guide member 24 retains the pair of conveying rollers 21 .
  • the pair of conveying rollers 21 is provided on the side of the pressing roller 16 in relation to the tangent line A, the direction in which the sheet (P) is drawn becomes the direction in which the sheet (P) is wound around the pressing roller 16 when the second sheet guide member 24 is eliminated (see FIG. 7 ). Therefore, when the pair of conveying rollers 21 conveys the sheet (P), the sheet (P) is drawn while the force pushing up the pressing roller 16 is generated. At this point, when the frictional state with the separating member 17 fluctuates to generate the fluctuation in tension F 3 of the sheet (P), the vibration is possibly generated in the direction in which the pressing roller 16 is pushed up to generate the noise.
  • the projection 24 a formed in the second sheet guide member 24 is projected toward the side of the separating member 17 from the tangent line A (the side on which the separating member 17 is disposed in relation to a tangent line A), and the gap is ensured with the first sheet guide member 22 . Therefore, the direction in which the sheet (P) is drawn becomes a direction of a coupling line B 3 , when the pair of conveying rollers 21 conveys the sheet (P) toward the downstream side so as to draw the sheet (P) from the nip between the pressing roller 16 and the separating member 17 .
  • the coupling line B 3 is a line drawn from the pressure-contact portion (nip portion) between the pressing roller 16 and the separating member 17 to the projection 24 a of the second sheet guide member 24 .
  • a tension F 3 in the direction of the coupling line B 3 is applied to the sheet (P), and the tension F 3 is divided into a force Ft 3 in the direction of the tangent line A and a force Fn 3 in a direction of the normal line C. Because the force Fn 3 in the direction of the normal line C is separated from the center 16 a of the pressing roller 16 , the pressing roller 16 is not pressed toward the center 16 a by the drawing force of the sheet (P) when the pair of conveying rollers 21 draws the sheet (P). Accordingly, the vibration and noise are reduced.
  • the sheet (P) cannot be guided to the desired position, the direction in which the sheet (P) is drawn does not become the direction of the tangent line A or the side of the separating member 17 in relation to the tangent line A, and possibly the generation of the vibration or noise cannot sufficiently be reduced.
  • the second sheet guide member 24 retains the pair of conveying rollers 21 , and the positional accuracy of the second sheet guide member 24 can be kept at a high level with respect to the pair of conveying rollers 21 . Therefore, the sheet P can be drawn more correctly in the direction of the tangent line A or onto the side of the separating member 17 in relation to the tangent line A, and the generation of the vibration or noise can be reduced more surely.
  • the second sheet guide member retains the pair of conveying rollers, and the positional accuracy of the second sheet guide member 24 can be kept at a high level with respect to the pair of conveying rollers 21 . Therefore, the sheet P can be drawn more correctly in the direction of the tangent line or the direction located on the side of the separating member in relation to the tangent line A (direction inclined from the tangent line toward the side on which the separating member is disposed based on the abutment portion), and the generation of the noise can be reduced more surely.
  • FIG. 10 is an explanatory view of a configuration of a sheet feeding device according to a third embodiment of the invention
  • FIG. 11 is an explanatory view of operation of a second sheet guide member of the sheet feeding device.
  • a sheet feeding device 1 C of the third embodiment has the same configuration as the second embodiment except that the second sheet guide member 24 is replaced with a second sheet guide member 25 . Therefore, the same component of FIGS. 10 and 11 is designated by the same numeral of FIGS. 8 and 9 , and the overlapping description is not presented.
  • the sheet feeding device 1 C of the third embodiment includes the sheet stacking member 13 , the feed roller 15 , the pressing roller 16 , the separating member 17 , the pressing spring 18 , and the pair of conveying rollers 21 .
  • the feed roller 15 is provided integrally or detachably.
  • the pressing roller 16 abuts on the separating member 17 to prevent the multi feed of the sheet P after the feed roller 15 is operated.
  • the separating member 17 is swingably supported by the swing support 17 a located on the upstream side in the conveying direction of the separating member 17 .
  • the sheet P placed on the sheet stacking member 13 is fed by the feed roller 15 and separated one by one by the separating member 17 .
  • the separating member 17 is pressed against the feed roller 15 by the pressing spring 18 .
  • the surface friction coefficient, contact angle, and shape of the separating member 17 are adjusted such that only one top-most sheet P is conveyed in each feed operation.
  • the separating member 17 is pressed against the pressing roller 16 to nip the sheet P therebetween.
  • the sheet P is fed to the pair of conveying rollers 21 while guided by the first sheet guide member 22 and the second sheet guide member 25 . Then, the sheet P is conveyed toward the downstream side by the pair of conveying rollers 21 so as to be drawn while nipped between the separating member 17 and the pressing roller 16 .
  • the pair of conveying rollers 21 is provided on the side of the pressing roller 16 from the tangent line A of the pressing roller 16 in the abutment portion between the pressing roller 16 and the separating member 17 (the side on which the separating member 17 is disposed in relation to a tangent line A).
  • the first sheet guide member 22 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the first sheet guide member 22 guides the sheet (P), fed to the feed roller 15 , on the side of the separating member 17 .
  • the second sheet guide member 25 is provided between the feed roller 15 and the pair of conveying rollers 21 , and the second sheet guide member 25 guides the sheet (P), fed to the feed roller 15 , on the side of the pressing roller 16 .
  • a projection 25 a is formed in the second sheet guide member 25 , and the projection 25 a is disposed on the tangent line A or at the position where the projection 25 a is projected toward the side of the separating member 17 from the tangent line A (the side on which the separating member 17 is disposed in relation to a tangent line A).
  • the projection 25 a ensures a gap with the first sheet guide member 22 .
  • the pair of conveying rollers 21 which is of an example of the sheet conveying unit and the second sheet guide member 25 which is of an example of the second guide member are exchangeably assembled integral with each other while a positional relationship is fixed between the pair of conveying rollers 21 and the second sheet guide member 24 .
  • the second sheet guide member 25 retains the pair of conveying rollers 21 .
  • a projection 25 a which is of an example of the second guide member is rotatably supported by the second sheet guide member 25 , and the projection 25 a is a rotating body which is driven according to the sheet (P) drawn from the nip between the separating member 17 and the pressing roller 16 .
  • the projection 25 a of the second sheet guide member 25 is disposed while projected toward the separating member 17 from to the tangent line A, and the projection 25 a is a roller which is rotatable with respect to the sheet (P).
  • the sheet (P) is conveyed to the downstream side by the pair of conveying rollers 21 so as to be drawn while nipped between the separating member 17 and the pressing roller 16 .
  • the pair of conveying rollers 21 is provided on the side of the pressing roller 16 in relation to the tangent line A, the direction in which the sheet (P) is drawn becomes the direction in which the sheet (P) is wound around the pressing roller 16 when the second sheet guide member 25 is eliminated (see FIG. 7 ). Therefore, when the pair of conveying rollers 21 conveys the sheet (P), because the sheet (P) is drawn while the force pushing up the pressing roller 16 is generated, the pressing roller 16 is vibrated to generate the noise.
  • the projection 25 a is projected from the tangent line A to ward the side of the separating member 17 while the gap with the first sheet guide member 22 is ensured, so that the direction in which the sheet (P) is drawn becomes the direction of a coupling line B 4 .
  • the coupling line B 4 is a line drawn from the abutment portion between the pressing roller 16 and the separating member 17 to the projection 25 a of the second sheet guide member 25 .
  • the sheet (P) is conveyed onto the downstream side by the pair of conveying rollers 21 so as to be drawn in the coupling line B 4 while nipped between the pressing roller 16 and the separating member 17 .
  • a tension F 4 applied to the sheet (P) in the direction of the coupling line B 4 is divided into a force Ft 4 in the direction of the tangent line A and a force Fn 4 in the direction of the normal line C. Because the force Fn 4 in the direction of the normal line C is separated from the center 16 a of the pressing roller 16 , the pressing roller 16 is not pressed toward the center 16 a by the sheet (P) drawn from the nip between the separating member 17 and the pressing roller 16 . Accordingly, the vibration and noise generated by the fluctuation of the force F 4 can be reduced.
  • the second sheet guide member 25 retains the pair of conveying rollers 21 , and the positional accuracy of the second sheet guide member 25 can be kept at a high level even after the pair of conveying rollers 21 is replaced. Therefore, the sheet P can be drawn more correctly in the direction of the tangent line or the direction located on the side of the separating member 17 in relation to the tangent line A, and the generation of the noise can be reduced more surely.
  • the projection 25 a of the second sheet guide member 25 is formed by a rotatable roller, and the projection 25 a is driven by the sheet (P). Therefore, the sheet (P) can be drawn with lesser drawing resistance compared with the second embodiment. Accordingly, the fluctuation in tension F 4 of the sheet (P) can further be decreased to reduce the generation of the vibration and noise in the pressing roller 16 .
  • the pair of conveying rollers 21 conveys the sheet (P) onto the downward side
  • the sheet (P) is slid while brought into pressure-contact with the second sheet guide member 25 . Therefore, the rubbing noise is possibly generated between the sheet (P) and the second sheet guide member 25 , or the friction between the sheet (P) and the second sheet guide member 25 possibly becomes the conveying resistance to generate variations in conveyance.
  • the projection 25 a of the second sheet guide member 25 is formed by the roller which is rotatable with respect to the sheet (P)
  • the rolling contact is generated between the sheet (P) and second sheet guide member 25 when the pair of conveying rollers 21 conveys the sheet (P). Therefore, the generation of the rubbing noise can be reduced while the variations in conveyance caused by the conveying resistance are also reduced. Accordingly, the fluctuation in speed of the sheet is decreased in the image forming portion G of FIG. 1 to improve the image quality.
  • the projection of the second sheet guide member is formed by the roller which is rotatable with respect to the sheet, the contact between the sheet and second sheet guide member can be changed from the sliding contact to the rolling contact when the pair of conveying rollers conveys the sheet. Accordingly, the generation of the rubbing noise can be reduced while the variations in conveyance caused by the conveying resistance are also reduced.
  • the invention can be implemented in another embodiment in which a part of or the whole of the configuration of the embodiments is replaced by an alternative configuration as long as the sheet is drawn from the nip between the pressing member and the separating member while the course of the sheet is bent toward the sheet feed member side.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Sheets, Magazines, And Separation Thereof (AREA)
US12/036,617 2007-03-01 2008-02-25 Sheet feeding device and image forming apparatus Abandoned US20080211166A1 (en)

Applications Claiming Priority (2)

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JP2007-052106 2007-03-01
JP2007052106A JP2008213998A (ja) 2007-03-01 2007-03-01 シート給送装置、および画像形成装置

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Publication number Priority date Publication date Assignee Title
JP2011016658A (ja) * 2009-06-11 2011-01-27 Ricoh Co Ltd シート搬送装置、これを用いた画像形成装置
CN102126626B (zh) * 2010-01-15 2013-02-20 致伸科技股份有限公司 自动馈纸装置
JP5606161B2 (ja) * 2010-06-02 2014-10-15 キヤノン株式会社 画像形成装置
JP6463127B2 (ja) * 2014-12-26 2019-01-30 キヤノン株式会社 画像読取装置及び画像形成装置
JP6840958B2 (ja) * 2016-09-01 2021-03-10 ブラザー工業株式会社 シート搬送装置及び画像形成装置
CN115649907B (zh) * 2022-12-28 2023-04-28 南京三隆包装有限公司 一种烟盒包装纸自动化快速印刷设备及其方法

Citations (3)

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US5083766A (en) * 1989-07-19 1992-01-28 Nisca Corporation Automatic sheet feeding device having a miniaturized structure
US6830244B2 (en) * 2001-09-11 2004-12-14 Nisca Corporation Sheet feeding apparatus
US20060237895A1 (en) * 2005-04-26 2006-10-26 Canon Kabushiki Kaisha Sheet feeding apparatus and image forming apparatus

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Publication number Priority date Publication date Assignee Title
JPH01162446A (ja) * 1987-12-18 1989-06-26 Hitachi Cable Ltd ループネットワーク
JP3254369B2 (ja) * 1996-04-11 2002-02-04 シャープ株式会社 転写材搬送装置
JP2000198561A (ja) * 1999-01-11 2000-07-18 Fuji Xerox Co Ltd 給紙装置
JP2000226130A (ja) * 1999-02-03 2000-08-15 Ricoh Co Ltd 用紙分離方法及び用紙搬送装置並びにインクジェット記録装置

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US5083766A (en) * 1989-07-19 1992-01-28 Nisca Corporation Automatic sheet feeding device having a miniaturized structure
US6830244B2 (en) * 2001-09-11 2004-12-14 Nisca Corporation Sheet feeding apparatus
US20060237895A1 (en) * 2005-04-26 2006-10-26 Canon Kabushiki Kaisha Sheet feeding apparatus and image forming apparatus

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CN101254862A (zh) 2008-09-03
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