JP6635723B2 - Sheet conveying device and image reading device - Google Patents

Description

  The present invention relates to a sheet conveying device having a function of correcting skew by hitting the leading end of a sheet, and an image reading apparatus including the same.

  2. Description of the Related Art Conventionally, an image forming apparatus such as an electrophotographic copying machine includes an image reading apparatus having an image reading unit, a mechanism for forming a toner image on an image carrier such as a photosensitive drum, and a mechanism for feeding a sheet from a feeding tray or the like. Have been.

  In the sheet conveyance path before the image reading unit of the image reading device and in the sheet conveyance path before the mechanism for forming an image of the image forming apparatus, the direction of the conveyed sheet is corrected, and the conveyance direction of the sheet and the sheet material. A resist correction mechanism that makes the directions substantially the same is provided.

  A general registration correction mechanism includes a registration roller and a space (hereinafter referred to as a thrust direction) provided in an entire area in a direction immediately upstream of the registration roller in a direction orthogonal to a conveyance direction on the conveyance surface (a depth direction in front of the apparatus, hereinafter a thrust direction). Loop space).

  In the registration roller, the surface of the driving roller is made of a high μ material such as rubber, and the surface of the driven roller is made of a low μ material such as polyacetal resin, in order to convey the sheet after the registration correction. The conveyance force of the registration roller is obtained by the frictional force between the rubber and the sheet generated by pressing the driven roller (hereinafter, pinch roller) to the driving roller by a spring or the like.

  The registration roller is stopped when the leading edge of the sheet is introduced into the nip, and feeds a further predetermined distance after the leading edge of the sheet reaches the nip. In this way, while bending the sheet in the loop space, the sheet tip position in the entire thrust direction is abutted against the registration roller nip using the stiffness of the sheet (restoring force for returning to the original position). Fit together.

  Thereafter, the sheet is conveyed by the registration roller in a state where the leading end position of the sheet is matched, so that the sheet is conveyed downstream of the registration roller with the direction of the sheet substantially the same as the conveyance direction.

  In Patent Literature 1, the registration correction function is enhanced by arranging the roller on the upstream side of the registration roller only near the conveyance center so that the sheet is easily turned. From such considerations, many conventional configurations use a registration roller as a conveyance roller immediately downstream of a feeding unit (arranged only near the center in the thrust direction).

JP 2002-265100 A

  By the way, with the recent improvement in the performance of the image forming unit and the image reading unit, higher sheet productivity tends to be required for higher productivity.

  However, increasing the speed at which the sheet is conveyed in the feeding section causes various problems such as a decrease in separation performance as a detrimental effect.

  In addition, the feeding of the feeding unit is performed by a feeding unit that conveys the sheet in the downstream direction of the conveying path, and the braking force by the separating unit acts on the sheet on the other side.

  This braking force tends to increase with the demand for improvement in separation performance. However, the action of this braking force varies depending on the wear of the separating means and the surface properties of the conveyed sheet. In other words, since the conveyance of the feeding unit is not stable due to the variation in the action of the braking force, when designing the productivity, the estimation is performed at the assumed minimum speed. Disadvantageous. For this reason, there is a case where the transport distance by the feeding unit is made as short as possible.

  However, if the distance from the feeding unit to the downstream registration roller (conveyance roller) is reduced, the sheet becomes stiff when trying to bend the sheet in the loop space as described above. Can not be pushed in the part.

  Further, in particular, when a sheet that is closed with a binder or the like and has a stiffness is further passed through with the folded portion toward the leading end, there is a possibility that the sheet may not be smoothly conveyed to the conveyance rollers. That is, the folded portion of the sheet is pinched at a position where the above-described loop space narrows in front of the transport roller, and the stiffness of the folded portion increases the transport load, and the transport may not be performed smoothly to the transport roller.

  SUMMARY OF THE INVENTION It is an object of the present invention to improve the pushing performance of a feeding unit onto a transport roller even in a configuration in which a distance from a feeding unit to a transport roller having a registration function is short.

In order to achieve the above object, the present invention provides a feeding means for feeding a sheet, a separating means for pressing and contacting the feeding means to form a feeding nip, and separating the sheets one by one; A conveying nip is formed downstream of the feeding unit and the separating unit , and a leading end of the sheet fed by the feeding unit and the separating unit is abutted against the carrying nip to correct a leading end position of the sheet. And a lower guide for guiding the sheet between the feeder and the feeder, wherein the lower guide is fed from the feed nip. A convex portion having an apex positioned above a feed nip straight line extending in a feeding direction, and a transport nip provided downstream of the apex of the convex portion, inclined toward the transport means, and extending from the transport nip in the transport direction. Have a, an inclined portion which intersects with the conveying nip linear and the feed nip linear intersect at the upstream side of the feeding direction of the feeding nip, characterized in that.

  According to the present invention, even when a sheet having a bent front end portion is conveyed, the folded portion abuts on the inclined surface, so that a factor that hinders the conveying force of the feeding unit can be reduced. Accordingly, even in a configuration in which the distance from the feeding unit to the transporting unit is short, the performance of pushing the feeding unit into the transporting unit can be improved.

FIG. 1 is a diagram schematically illustrating an entire configuration of an image reading apparatus including a sheet conveying device. Perspective view of the feeding unit of the sheet conveying device FIG. 2 is a diagram illustrating a driving configuration of a sheet conveying device. FIG. 2 is a diagram illustrating a driving configuration of a sheet conveying device. Diagram showing the block configuration of the sheet conveying device FIG. 4 is a diagram illustrating a feeding operation control sequence of the sheet conveying apparatus. FIG. 2 is a perspective view of the sheet conveying apparatus according to the first embodiment. FIG. 4 is a cross-sectional view of the sheet conveying apparatus according to the first embodiment. Top view of only the lower guide side of the sheet conveying device according to the first embodiment FIG. 9 is a perspective view of a sheet conveying apparatus according to a second embodiment. Sectional view of a sheet conveying device according to a second embodiment. FIG. 9 is a table illustrating simulation results of conveying a sheet having a bent portion by the sheet conveying apparatus according to the second embodiment.

  Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

  FIG. 1 illustrates an example of a document conveying device (hereinafter, ADF) to which a sheet conveying device can be applied, and an image reading device (hereinafter, a reader) that reads image information on a sheet conveyed by the ADF.

  The ADF 1 has a feed tray 2 as a mounting table above. The sheets on the feed tray 2 are sequentially fed out by the pickup roller 5 from the uppermost sheet. The fed-out sheets are separated one by one by a separation roller 7 as a separating unit while being fed to a feeding roller 6 as a feeding unit. The separating roller 7 is pressed against the feeding roller 6 to form a feeding nip.

  The transport path 20 is formed by the upper guide 15 and the lower guide 18. The lower guide 18 has a shape inclined upward from the downstream of the pickup roller 5, and guides the sheet placed on the feed tray 2 to the downstream transport path 21.

  The sheets separated and fed one by one by the feeding roller 6 and the separating roller 7 are once abutted against a pair of conveying rollers 206 downstream in the feeding direction, and the leading end position is corrected (registration correction). The configuration of the transport roller pair 206 as transport means will be described later.

  Thereafter, the sheet is transported further downstream of the transport path 20 by the transport roller pair 206, and is transported via the transport path 21 onto the platen unit 8 which is the image reading position of the ADF main body.

  A reader is arranged below the ADF 1. Inside the reader, there is a scanning body 31 as an image reading means for reading the image of the sheet. The scanning body 31 scans in the left-right direction along the guide member 33 in order to read image information of a sheet placed on the glass 34 arranged above.

  When a sheet is conveyed by the ADF 1, the scanning body 31 moves below the reading glass 30 to read image information of the sheet passing over the reading glass 30, and is fixed at that position during sheet conveyance. .

  An image is formed on the reading element 32 by a plurality of mirrors and finally by an image forming means inside the scanning body 31, and the reading element 32 performs photoelectric conversion. Note that examples of the reading element include a CMOS sensor, a CCD sensor, and a CIS sensor.

  The sheet that has passed through the reading glass 30 is discharged onto a discharge tray 19 by a discharge roller 9. The sheets are placed on the feed tray 2 in order of 1 page (2 pages), 3 pages (4 pages), etc. from the top, and the ADF 1 It is detected that it is placed on the.

  FIG. 2 is a cross-sectional view of the transport roller pair 206, the feed roller 6 and the separation roller 7, and the loop space 22 immediately upstream of the transport roller pair 206 in the ADF 1.

  In the ADF 1, the feeding unit has a feeding roller 6 and a pickup roller 5 as feeding means. The feed roller 6 is held on a shaft 62. The arm 102 rotates (elevates) the pickup roller 5 about the shaft 62. The driving force is transmitted from the shaft 62 to the pickup roller 5 by the driving transmission belt T2 (see FIG. 3). The drive transmission belt T2 is stretched by pulleys P3 and P4.

  FIG. 3 and FIG. 4 are diagrams showing a drive configuration of the ADF 1. Each arrow in the figure represents the rotation direction of each drive gear when viewed from above.

  In the ADF 1, the pickup roller 5 and the feed roller 6 forming the feed unit, and the transfer roller 206a forming the transfer roller pair 206 are driven by the same motor M1. The transport roller 206a is connected to the gear pulley PZ2, and is rotated by the drive transmitted from the motor M1 via the drive transmission belt T1.

  The driving torque of the motor M1 is transmitted downstream of the gear pulley PZ2 to the gear Z6 via a gear Z4 and a gear Z5 coaxially connected to the gear Z4, and the shaft 62 connected to the gear Z6 is rotated.

  The gear Z3 is a gear connected to the electromagnetic clutch CL, and can transmit the drive only when the current flows to the electromagnetic clutch CL and the drive can be transmitted.

  When the motor M1 is rotating in the normal rotation direction (FIG. 3), the feeding unit is rotationally driven in the direction for transporting the sheet in the downstream direction, whereas the transport roller 206a is stopped when the leading edge of the sheet is reached. Alternatively, the feeding unit is rotationally driven in a direction opposite to the sheet conveying direction (a direction for conveying the sheet in the upstream direction).

  When the motor M1 rotates in the normal rotation direction, the feed roller 6 rotates in the same manner as the shaft 62, and the pickup roller 5 is lowered from the standby position by the torque generated by the spring clutches TL2 and TL3 connected to the shaft 62. In addition, the pickup roller 5 is coaxially connected to a pulley P4, and rotational drive is transmitted by a pulley P3 connected to a shaft 62 and a drive transmission belt T2 stretched between the pulleys P3 and P4.

  On the other hand, when the motor M1 rotates in the reverse direction (FIG. 4), the feeding unit is stopped, and the transport roller 206a is driven to rotate in the direction of transporting the sheet in the downstream direction.

  At this time, the rotational drive of the motor M1 drives the gear pulley PZ2 to rotate via the drive transmission belt T1, but the rotational drive of the gear pulley PZ2 is not transmitted to the gear Z5 because of the one-way clutch included in the gear Z4. That is, the rotational drive of the motor M <b> 1 in the reverse rotation direction is not transmitted to the feed roller 6 and the pickup roller 5. The feed roller 6 and the pickup roller 5 of the feed unit follow the behavior of the sheet conveyed by the conveying roller 206a by one-way clutches provided on the inner peripheral side.

  FIG. 5 is a block diagram showing the electrical configuration of the ADF. The configuration of the ADF will be described with reference to FIG.

  In FIG. 5, the ADF is controlled by an ADF control unit. The information of the transport sensor Sn is processed by the CPU 800 based on a sequence stored in the ROM 801 in advance, and the driving unit M is driven.

  The image reading is performed by a reader control unit that controls the image reading unit, and a trigger signal for starting reading obtained from the conveyance sensor Sn in the ADF is sent from the ADF control unit to the reader control unit, or the size of the read image is changed. In order to adjust the driving of the driving unit M to adjust the (sub-scanning magnification), the specification is such that processing data is exchanged from the reader control unit to the ADF control unit.

  In the reader control unit, the image data read by the reading element 32 is processed by the image processing unit based on image processing parameters and sequences set in advance in the ROM 811 and the RAM 812. The processed image data is transferred to a controller or the like on the printer side through serial communication.

  FIG. 6 shows a control sequence for performing the ADF feeding operation based on FIG. Hereinafter, the feeding operation of the ADF will be described with reference to FIGS.

  When a sheet is placed on the feed tray 2, the set detection sensor 3 detects that a sheet has been set on the feed tray 2 (S101). In a state where the sheet setting is detected, the process waits until a user inputs a command for starting the feeding operation (S102).

  If the command is input, the ADF issues a driving command to the driving means M, and starts the feeding operation by driving the motor M1 (S103). At this time, the motor M1 rotates in the normal rotation direction (the direction of the solid line arrow in FIG. 3), the shaft 62 rotates through the drive transmission means (PZ2, Z4, Z5, Z6), and the feed roller 6 and the pickup roller 5 Rotates. When the shaft 62 rotates, the arm 102 descends toward the sheet placed on the feed tray 2 via the spring clutches TL2 and TL3. Thereby, the pickup roller 5 held by the arm 102 descends and comes into contact with the sheet.

  When the pickup roller 5 comes into contact with the sheet, the spring clutches TL2 and TL3 idle with a predetermined torque to the arm 102, and apply a contact pressure to the sheet to the pickup roller 5.

  At the same time, the reader control section moves the scanning body 31 in the reader below the reading glass 30 and drives an illumination device for irradiating the sheet with illumination (S104, S105). At this time, shading correction (reference correction) is performed by the image processing unit, and the parameters required for image processing at that time are temporarily stored in the RAM 812.

  During the feeding operation, every time the rear end of the fed sheet is detected by the conveyance sensor Sn arranged upstream of the platen unit 8, the presence or absence of the sheet on the feeding tray is checked, and as long as the presence of the sheet is detected. The feeding operation is repeated (S110).

  The scanning element 31 drives the reading element 32 by the reader control unit every time the leading edge of the sheet is detected by the conveyance sensor Sn (S106, S107). Then, the reflected light of the illumination applied to the sheet passing through the flow reading glass 30 is photoelectrically converted by the reading element 32 to acquire image information, and the image processing unit stores the image processing parameters stored in the RAM 812 described above. Alternatively, image processing is performed based on parameters set in the ROM 811 in advance. Further, the image data is transferred to a printer controller or the like through serial communication.

  The drive of the reader control unit is terminated after a predetermined time when the trailing edge of the sheet is detected by the transport sensor Sn (S108, S109), but is driven again when the transport sensor Sn detects the next sheet. . While the sheet is conveyed, the switching of the drive of the reading element 32 is repeated based on the detection result of the conveyance sensor Sn.

  When all the sheets placed on the feed tray are fed (S110), the set detection sensor 3 determines that there is no sheet placed, and the ADF control unit stops the feeding operation (S113).

  When the reader control unit also determines that there is no sheet placed by the set detection sensor 3 (S110), the driving of the illumination device is terminated, and the position of the scanning body 31 is also set to the standby position (shading) from below the flow reading glass 30. (Correction position, etc.) (S111, S112).

  After the feed operation is stopped, the motor M1 is rotated in the reverse direction (in the direction of the dotted arrow in FIG. 3) (S114), and the electromagnetic clutch CL is energized to be in a state where the drive can be transmitted. As a result, the drive of the motor M1 is transmitted from the gear pulley PZ2 to the gear Z3, and the shaft 62 is driven via the gears Z5 and Z6 coaxially connected (in the direction of the dotted arrow in FIG. 4). Due to the rotation of the shaft 62, the arm 102 moves up in the direction away from the feed tray 2 and waits for the next job sheet set detection (S115).

  When the pickup roller 5 is completely lifted by the arm 102, the transmission of drive is interrupted by a predetermined torque by the torque limiter TL1 adjacent to the gear Z5, so that the motor M1 is protected from overload and the position of the pickup roller 5 is maintained. You.

  When the pickup roller 5 lands on the upper surface of the sheet during the feeding operation, pressure is applied to the sheet. In the present embodiment, a spring clutch is exemplified as the pressure applying means. However, the present invention is not limited to this, and another pressure applying means such as a compression spring may be used.

  When the motor M1 rotates in the reverse direction by the spring clutch, the arm 102 is rotated in the direction opposite to the direction of the arrow in FIG. 2 to lock the pickup roller 5 for raising.

[Example 1]
FIG. 7 is a perspective view of the lower guide 18 side from the separation roller 7 to the conveying roller 206a of the sheet conveying apparatus according to the first embodiment.

  The upstream side of the lower guide (lower guide means) 18 has a slope portion for guiding the sheet placed on the feeding tray 2 to the separation roller 7 (or the feeding nip P67 with the feeding roller 6). In particular, in a portion corresponding to the separation roller 7 in the thrust direction, a high friction sheet 182 and a high friction sheet 182 that impart frictional resistance to a sheet bundle guided by a plurality of sheets immediately upstream of the separation roller 7 are provided. A support member 181 for supporting with high rigidity is provided.

  The lower guide 18 on the downstream side of the separation roller 7 is formed with projections 18a and 18b having a shape protruding in the sheet passing direction. The convex portion (first convex portion) 18a at the center in the width direction orthogonal to the sheet conveying direction is formed corresponding to the position of the separation roller 7 in the sheet conveying direction. The shapes of the protrusions (second protrusions) 18b on both sides in the width direction will be described later.

  Downstream of the convex portion 18a, one transport roller 206a forming the transport roller pair 206 is disposed, and the entrance sensor S2 for detecting the position of the leading end of the sheet transported by the feed unit is also disposed at substantially the same position. I have. A plurality of transport rollers 206a are arranged in the thrust direction, and the material is made of a rubber member such as EPDM, silicon, urethane, or the like. An entrance sensor S2 is arranged to swing between the plurality of transport rollers 206a.

  A guide member (guide means) 18s for guiding the leading end of the sheet is disposed immediately upstream of the conveying roller 206a. The guide member 18s has a thin shape and is made of a PET sheet, a SUS sheet, or the like because the tip of the guide member 18s is desired to be close to the transport roller 206a.

  As described above, the transport roller 206a is a rubber member and has a high coefficient of friction with respect to the sheet. Therefore, when the leading edge of the sheet touches the transport roller 206a, the transport roller 206a may be damaged (turned over, scratched, or the like). However, since the guide roller 18s covers the transport roller 206a up to just before the nip, the above-described damage can be reduced.

  FIG. 8 is a cross-sectional view of the conveyance path 20 from the separation roller 7 to the conveyance roller 206a of the sheet conveyance device according to the first embodiment. Here, a sheet P closed and stored with a binder or the like and having a habit at the end is illustrated. FIG. 8 illustrates a state immediately before the sheet P having passed the paper with the folded portion as the leading end during the ADF conveyance reaches the conveyance roller pair 206.

  The upper guide 15 between the feeding roller 6 and the conveying roller pair 206 is configured to be retracted upward with respect to the lower guide 18, and a loop space 22 is secured between the upper guide 15 and the lower guide 18. The loop space 22 is a space for absorbing an extra amount of the sheet conveyed to the feeding roller 6 after the front end is abutted against the conveying roller pair 206.

  The conveyance amount of the feed roller 6 is a conveyance while carrying a conveyance load (caused by a force for damming the sheet) by the separation roller 7, and the conveyance load depends on a worn state of the separation roller or a type of the sheet. Will vary.

  Therefore, the set value of the conveyance amount until the leading end of the sheet abuts on the conveyance roller pair 206 is set to an amount that can be safely reached even when the conveyance amount of the feeding roller 6 is the minimum. However, if the feeding amount of the feeding roller 6 is sufficiently ensured, the sheet is fed more than the leading end of the sheet reaches the feeding roller pair 206. The excessively fed portion is absorbed in the loop space 22.

  The loop space 22 becomes narrower toward the downstream side, and becomes approximately 2 mm immediately upstream of the pair of conveying rollers 206. However, a guide member 18s is disposed at a portion corresponding to the transport roller 206a in the thrust direction. As described above, since the guide member 18s needs to cover the transport roller 206a, it is disposed at substantially the same height as the transport nip straight line 206N of the transport roller pair 206 in the direction perpendicular to the sheet transport surface. Therefore, the distance between the upper and lower guides is reduced to about 1 mm.

  The projections 18a and 18b of the lower guide 18 are formed with an inclined portion 18i that is inclined downward toward the pair of conveying rollers 206 downstream of the vertex 18at that protrudes most toward the sheet passing surface. The vertices 18at of the convex portions 18a and 18b are located above (on the upper guide 15 side) the feed nip straight line 67N extending in the feed direction from the feed nip P67 between the feed roller 6 and the separation roller 7. Thus, when the sheet is pulled out from the feeding roller 6 and the separation roller 7 by the conveyance roller pair 206, the separation roller 7 can be prevented from being pushed down by the tension of the sheet.

  When the separation roller 7 is pushed down by the sheet tension, the nip pressure between the feeding roller 6 and the separation roller 7 therebetween decreases, and the damping performance of the next sheet of the conveyed sheet decreases, and the weight of the next sheet decreases. The possibility of transmission occurring increases. Further, the nip pressure between the feed roller 6 and the separation roller 7 is not stabilized, and the possibility of generating abnormal noise due to the nip pressure increases.

  The inclined portion 18i is formed at a distance of 10 to 20 mm or more upstream from a position where the interval between the upper and lower guides is about 1 mm at or immediately upstream of the transport nip P206 of the transport roller pair 206.

  As described above, when the leading end PL of the sheet P having a folded portion at the leading end passes immediately upstream of the conveying roller pair 206, the leading end PL comes into contact with the upper guide 15 at a portion where the vertical guide interval is narrowed, and the folded portion PF is It comes into contact with the inclined portion 18i. At this time, the folded portion of the sheet P having a folded portion at the leading end is crushed by the narrowed vertical guide interval.

  Therefore, a contact force FP corresponding to the stiffness of the folded portion acts on the inclined portion 18i. The contact force FP also acts on the sheet P in the vertical direction on the inclined portion 18i as shown in FIG.

  As for the contact force FP, downstream components F206 and F6 act on the sheet P, respectively. However, since the inclined portion 18i is inclined downward toward the conveying roller pair 206, the upstream component F6 can be made relatively smaller than the downstream component F206. Thus, the conveying force of the feed roller 6 can be applied to the sheet front end without being hindered by the upstream component F6.

  Further, the inclined portion 18i is formed at a distance of 10 to 20 mm or more upstream from a position where the vertical guide interval is about 1 mm at or immediately upstream of the transport nip P206 of the transport roller pair 206. Thus, when the sheet P having a bent portion at the leading end is conveyed, the folded portion can be brought into contact with the inclined portion 18i, and the conveying force of the feeding roller 6 can be applied to the leading end of the sheet as described above.

  By the way, the feed nip straight line 67N of the feed roller pair (the feed roller 6 and the separation roller 7) 67 of the present embodiment is set toward the loop space 22 on the upper guide side.

  As a result, not only can the sheet guided by the support member (inclined) 181 upstream of the feed roller pair be smoothly introduced into the feed nip P67 of the feed roller pair, but also after the sheet leading edge reaches the transport roller pair 206, Buckling to the loop space 22 is likely to occur.

  However, when the folded portion of the sheet P having a folded portion at the leading end is in contact with the inclined portion 18i, the upstream side of the folded portion of the sheet P is in a state where it is easy to bend in the entire region in the width direction. The apex 18at tends to further induce the curvature.

  In particular, by setting the feed nip straight line 67N of the feed roller pair 67 to the loop space 22 side, it is possible to easily form a loop in a normal sheet. A difference in the feeding direction occurs, and the sheet is easily curved.

  If the bending of the sheet progresses in the upstream portion from the bent portion, the transport amount by the feeding roller 6 is absorbed by the curved portion, and the leading end PL of the sheet P abuts against the transport roller pair 206 insufficiently. There is a possibility of becoming.

  However, in this embodiment, the intersection between the transport nip straight line 206N of the transport roller pair 206 and the feed nip straight line 67N of the feed roller pair 67 is set to It is set outside on the upstream side between the feed roller pair 67.

  With this configuration, the protrusion amount of the vertex 18at of the convex portion from the imaginary line 1 (the two-dot chain line in FIG. 8) connecting the transport nip P206 of the transport roller pair and the feed nip P67 of the feed roller pair is calculated as follows. , Can be set smaller. Specifically, the intersection point PI of the transport nip straight line 206N and the feed nip straight line 67N can be set smaller than that in the case where the intersection point PI is provided between the transport roller pair 206 and the feed roller pair 67. Thus, in a normal sheet, it is possible to easily form a loop in the loop space 22 and to reduce the occurrence of bending at a portion upstream of the bent portion of the sheet P having a bent portion at the front end.

  FIG. 9 is a diagram illustrating the lower guide side of the sheet conveying device according to the first embodiment as viewed from above the sheet conveying surface.

  As described above, a plurality of transport rollers 206a are arranged in the thrust direction. In this embodiment, four transport rollers 206a are arranged in the thrust direction. Of the plurality of transport rollers 206a, the center two in the thrust direction correspond to the position of the separation roller 7 in the sheet transport direction. When the sheet is pulled out from the feeding roller pair 67 by the conveying roller pair 206, conveyance resistance by the separation roller 7 is generated. Therefore, by adjusting the position in the thrust direction, it is possible to suppress wrinkles of the sheet due to the conveyance resistance. I have.

  Further, two of the plurality of transport rollers 206a on the outside in the thrust direction also have a registration function. The sheet conveyed to the feed roller pair 67 is often skewed. In this case, the leading end of the sheet comes into contact with one of the two outer sides of the conveying roller 206a, and then the leading end abuts on the conveying roller on the other side to correct the position of the leading end of the sheet. At this time, the position of the sheet can be corrected more stably if the distance between the first contacting roller and the next contacting roller is as large as possible.

  Therefore, the position of the leading end of the sheet is corrected by the two outside of the conveying roller 206a in the thrust direction. In the present embodiment, the transport rollers 206a are arranged at the minimum necessary to reduce the cost of parts, and the interval 206a2 between the outer transport rollers 206a, 206a is set to be about 10 to 20 mm smaller than the sheet having the minimum width in terms of product specifications. Has been placed.

  On the other hand, the widths of the projections 18a and 18b of the lower guide 18 in the thrust direction are set as follows. That is, the width (the length in the thrust direction) of the projection 18 a at the center in the thrust direction is set to be substantially the same as the length of the separation roller 7. On the other hand, the interval 18b2 between the protrusions 18b on both sides in the thrust direction is set wider than the interval 206a2 between the outer transport rollers 206a, 206a of the transport roller 206a.

  Accordingly, in the process in which the leading end of the sheet P having a bent portion at the leading end which is conveyed while being skewed to the feeding roller pair 67 abuts on one of the two outer sides of the conveying roller 206a, the sheet is conveyed by the stiffness of the bent portion The resistance can be effectively reduced by the inclined portion 18i as described above.

  The convex portions 18b, 18b on both outer sides of the lower guide extend to the outside so as to be larger by 20 to 30 mm than both outer sides of the transport roller 206a, but do not extend further outside. This is because the provision of the projections 18b, 18b more than necessary closes the transport path 20 so that the transport resistance does not increase.

  The length 18s2 between the outer ends of the guide member 18s is wider than the interval 206a2 between the outer rollers of the transport roller, but is 20 to 20 times longer than the interval 18b2 between the outer convex portions 18b of the lower guide 18. It is set to be 30 mm narrower.

  On both outer sides of the guide member 18s, inclined portions 18i are extended, and as shown in FIG. 8, in particular, the inclination angle of the inclined portion 18i below the guide member 18s is set to be larger.

  As a result, the area of about 1 mm between the upper and lower guides immediately upstream of the pair of conveying rollers 206 is kept to a necessary minimum, thereby maximizing the effect of the above-described inclined portion 18i and reducing the conveying resistance of the conveying path 20.

The heights of the ridges 18a and 18b may be set lower than the vertices 18at of the central ridge 18a. With such a configuration, in the thrust direction, sagging due to the sheet's own weight is caused by the difference between the heights of the apexes 18at of the convex portions 18b on both outer sides and the convex portion 18a of the central portion. Can produce a convex stiffness. Thereby, the induction of the bending can be further reduced in the upstream portion of the bent portion PF of the sheet P having the bent portion at the front end. Further, even in a sheet having a small thickness (a basis weight of 45 [g / m ² ] or less), the performance of abutting the leading end against the transport roller pair 206 can be improved by applying a convex stiffness at the center. .

  According to the present embodiment, the downstream side of the vertex 18at of the convex portion 18a of the lower guide 18 intersects with the transport nip straight line 206N extending in the transport direction from the transport nip P206 of the transport roller pair 206, and moves toward the transport roller pair 206. It is formed on an inclined portion 18i that is inclined. Accordingly, even when a sheet having a bent habit at the leading end is conveyed, a factor that hinders the conveying force by the feeding roller 6 can be reduced by the bent portion abutting on the inclined portion 18i.

  Further, a feed nip straight line 67N extending from the feed nip P67 of the feed roller 6 and the separation roller 7 in the feed direction and the transfer nip straight line 206N are located on the upstream side between the feed roller 6 and the transfer roller pair 206. Is provided with an intersection point PI on the outside. Thus, in a normal sheet, it is possible to easily form a loop in the loop space 22 and reduce the occurrence of curving at a portion upstream of the bent portion of the sheet having a bent portion at the front end.

  Further, the length (the length in the thrust direction) 18s2 between both outer ends of the guide member 18s is made larger than the interval 206a2 between the outer transport rollers 206a, 206a of the transport roller 206a, and the protrusions 18b, The length of the guide member 18b in the thrust direction (interval 18b2) is larger than the length of the guide member 18s in the thrust direction (interval 18s2). This makes it possible to minimize the transport resistance of the transport path due to the provision of the projections.

  With the above configuration, even in a configuration in which the distance from the feeding unit to the pair of conveying rollers having the registration function is short, it is possible to provide a sheet conveying device that improves the performance of pushing the feeding roller into the pair of conveying rollers.

[Example 2]
FIG. 10 is a perspective view of the lower guide 18 side from the separation roller 7 to the conveying roller 206a of the sheet conveying apparatus according to the second embodiment.

  The difference from the above-described first embodiment is that, instead of the protrusion 18a at the center in the thrust direction, a driven rotary member 7b is disposed immediately downstream of the separation roller 7 as auxiliary means for assisting sheet conveyance. Further, on both outer sides in the thrust direction, convex portions 18b, 18b of the lower guide 18 are arranged.

  The driven rotary member 7b is arranged to prevent the separation roller 7 from being pushed down by the tension of the sheet when the sheet is pulled out from the feeding roller pair 67 by the conveying roller pair 206, and the thrust direction in the first embodiment described above. They are arranged for the same purpose as the central projection 18a.

  However, in the present embodiment, by disposing the driven rotator 7b, the sheet surface at the time of pull-out comes into contact with the driven rotator 7b, but the driven rotator 7b rotates following the sheet surface being conveyed. Thus, scratches generated on the sheet surface can be reduced.

  FIG. 11 is a cross-sectional view of the conveyance path 20 from the separation roller 7 to the conveyance roller 206a of the sheet conveyance device according to the second embodiment.

  The driven rotary member 7b arranged in this embodiment is arranged so as to protrude toward the loop space 22 from the feed nip straight line 67N of the feed roller pair for the above-described purpose.

However, the height of the apex 18bt of the protrusion 18b is formed at a position lower than the driven rotor 7b on both sides. With such a configuration, in the thrust direction, sagging of the sheet due to its own weight is caused by the difference in height between the driven rotator 7b and the apex 18bt of the protruding portion 18b, and the central portion of the sheet is convex with respect to the sheet. Can be caused. Thereby, the induction of bending can be further reduced in the upstream portion of the folded portion of the sheet P having the folded portion at the leading end. Further, even in a sheet having a small thickness (basis weight of 35 to 45 [g / m ² ]), it is possible to improve the abutting performance of the leading end against the conveying roller pair 206 by giving a convex stiffness at the center. it can.

FIG. 12 shows a sheet P (basis weight 80 [g / m ² ], folded tip height 10 mm) having a folded portion at the leading end in the second embodiment, which is transported from the feeding roller pair 67 to the transporting roller pair 206. Of the transport load torque of the feed roller 6 (illustrated in FIG. 12A) and the guide reaction force of the vertical guides 15 and 18 (illustrated in FIG. 12B and FIG. 12C). It is.

  The horizontal axis is the time axis (unit: sec), and 0 is when the leading edge of the sheet P reaches the transport roller pair 206. The vertical axis indicates the torque (Nmm / mm) in FIG. 12A and the contact pressure (N / mm) in FIGS. 12B and 12C.

  12A, the transport load torque of the feed roller 6 in the present embodiment does not increase before the leading edge of the sheet P reaches the transport roller pair 206, and it can be transported smoothly. Understand.

  12B and 12C, when the reaction force of the upper and lower guides exceeds 0.04 [N / mm], the upstream portion buckles from the contact point with the guide, and the leading end of the sheet P is in the downstream direction. However, in the present embodiment, it can be seen that the sheet can be smoothly conveyed without being maximized before reaching the conveying roller pair 206.

  Note that, in the present embodiment, even if the outer convex portions 18b of the lower guide 18 are also replaced by driven rotators, an inclined portion 18i that is inclined toward the transport roller pair 206 is provided on the downstream side thereof. The same effect can be obtained by lowering the arrangement position below the driven rotor 7b.

  According to this embodiment, the following effects can be obtained in addition to the effects of the above-described embodiment. That is, by disposing the driven rotating body 7b in the central portion in the thrust direction, the driven rotating body 7b follows and rotates on the sheet surface when the sheet is pulled out, so that the scratches generated on the sheet surface can be reduced. it can.

P67: feeding nip P206: transport nip PF: bent portion PI: intersection point PL: tip 6: feeding roller 7: separating roller 7b: driven rotary member 15: upper guide 18: lower guides 18a, 18b: convex portions 18at, 18bt ... Apex 18i ... Incline 18s ... Guide members 20, 21 ... Convey path 22 ... Loop space 67 ... Supply roller pair 67N ... Supply nip straight line 206 ... Conveyer roller pair 206N ... Conveyer nip straight line

Claims (10)

Feeding means for feeding the sheet,
Separating means for pressing the said feeding means to form a feeding nip and separating sheets one by one ;
The transporting nip is formed downstream of the feeding unit and the separating unit to form a transport nip, and the leading edge of the sheet fed by the feeding unit and the separating unit is abutted against the transport nip, and the leading edge of the sheet is Conveying means for conveying the sheet after correcting the position ,
Lower guide means for guiding a sheet between the feeding means and the transport means,
In the sheet conveying device having
The lower guide means is provided with a convex part whose apex is located above a feed nip straight line extending in the feed direction from the feed nip, and is provided downstream from the apex of the convex part, and is inclined toward the transport means. , have a, an inclined portion which intersects with the conveying nip line extending in the conveying direction from the conveying nip,
The feed nip straight line and the transport nip straight line intersect on the upstream side in the feed direction of the feed nip,
A sheet conveying device, characterized in that: A guide unit is provided on the lower guide unit, and has a guide unit for guiding a sheet leading end to the transport unit.
A plurality of the transport means are arranged in the thrust direction,
The guide means is arranged at substantially the same height as the transfer nip straight line,
The length in the thrust direction of the guide means is larger than the interval between both outer sides where a plurality of the transport means are arranged,
The thrust direction of the length of the convex portion of the lower guide means, the sheet conveying device according to claim 1, characterized in that it is larger than the thrust direction of the length of the guide means. The thrust direction of the length of the convex portion of the lower guide means to claim 2, characterized by being formed so as 20~30mm greater respectively than the length between both outer ends of the thrust direction of said guide means The sheet conveying device as described in the above. The convex portion of the lower guide has a first convex portion formed at a central portion in the thrust direction, and second convex portions formed on both outer sides in the thrust direction of the first convex portion,
A guide unit is provided on the lower guide unit, and has a guide unit for guiding a sheet leading end to the transport unit.
A plurality of the transport means are arranged in the thrust direction,
The guide means is arranged at substantially the same height as the transfer nip straight line,
The length in the thrust direction of the guide means is larger than the interval between both outer sides where a plurality of the transport means are arranged,
The length in the thrust direction of the first convex portion at the center of the lower guide means is formed to be substantially the same length as that of the feeding means,
Thrust direction between the second convex portions of the both outer sides of the lower guide means, the sheet conveying device according to claim 1, characterized in that it is larger than the thrust direction of the length of the guide means. The distance in the thrust direction between the second convex portions on both outer sides of the lower guide means is formed to be larger by 20 to 30 mm than both outer ends in the thrust direction of the guide means. 5. The sheet conveying device according to 4 . Feeding means for feeding the sheet,
Separating means for pressing the said feeding means to form a feeding nip and separating sheets one by one ;
The transporting nip is formed downstream of the feeding unit and the separating unit to form a transport nip, and the leading edge of the sheet fed by the feeding unit and the separating unit is abutted against the transport nip, and the leading edge of the sheet is Conveying means for conveying the sheet after correcting the position ,
Auxiliary means for assisting the conveyance of a sheet between the feeding means and the conveyance means,
Lower guide means provided on both outer sides in the thrust direction of the auxiliary means and guiding a sheet between the feeding means and the transport means,
In the sheet conveying device having
The auxiliary means is provided so as to protrude above a feed nip straight line extending in a feed direction from the feed nip,
The lower guide unit is a projection located below the auxiliary unit, and a transport nip straight line that is provided downstream from the vertex of the projection and is inclined toward the transport unit and extends in the transport direction from the transport nip. an inclined portion crossing, was perforated,
The feed nip straight line and the transport nip straight line intersect on the upstream side in the feed direction of the feed nip,
A sheet conveying device, characterized in that: A guide unit is provided on the lower guide unit, and has a guide unit for guiding a sheet leading end to the transport unit.
A plurality of the transport means are arranged in the thrust direction,
The guide means is arranged at substantially the same height as the transfer nip straight line,
The length in the thrust direction of the guide means is larger than the interval between both outer sides where a plurality of the transport means are arranged,
7. The sheet conveying apparatus according to claim 6 , wherein a length of the projection of the lower guide in the thrust direction is larger than a length of the guide in the thrust direction. The sheet according to claim 7 , wherein the gap in the thrust direction of the convex portion of the lower guide means is formed to be larger by 20 to 30 mm than both outer ends in the thrust direction of the guide means. Transport device. Said conveying means, to any one of claims 1 to 8, characterized in that rotating the stop or the sheet conveying direction and reverse direction at the time of arrival of the sheet front end fed by the feeding means The sheet conveying device as described in the above. An image reading apparatus, comprising: a sheet conveying apparatus that separates and feeds sheets one by one, and an image reading unit that reads an image of a sheet that has been conveyed by the sheet conveying apparatus.
Wherein a sheet conveying apparatus, an image reading apparatus characterized by having a sheet conveying device according to any one of claims 1 to 9.

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