JP2013146070A - Document feeder, image reader equipped with the same, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document feeder capable of suppressing fluctuation in the conveyance state of a document while a conveyance load is reduced during the conveyance of the document, and to provide an image reader and an image forming device equipped with the document feeder.SOLUTION: In a document feeder 27, a pair of first and second conveying rollers 38 and 39 are arranged respectively upstream and downstream from a reading guide 73 of a conveyance guide 71, and first following rollers 77a-77c are arranged upstream from the opposing surface 73d of the reading guide 73, the surface 73d being opposed to a first image reading region R1. The first following rollers 77a-77c are arranged along the width direction of the document. Among the first following rollers 77a-77c, the first following roller 77b disposed in the center of the width direction is disposed downstream in a document conveyance direction rather than the other first following rollers 77a and 77c.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus that scans and reads a document and is used in a digital copying machine, an image scanner, and the like, and particularly to an image forming apparatus including the image reading apparatus. The present invention relates to a sheet-through type image reading apparatus.

  2. Description of the Related Art Conventionally, in an image reading apparatus mounted on a multifunction machine using an electrophotographic process, a document is conveyed so that a sheet-like document is sequentially sent to a document placing table and discharged from the document placing table after the reading is completed. Some have a device (Automatic Document Feeder). In such an image reading apparatus, a sheet-through method in which a document is automatically conveyed and read by a document conveying device while the document press is closed, and the document press is opened and closed each time reading is performed on a document placement table (contact glass). Two types of reading methods are possible: a document fixing method in which the original is replaced one by one and the optical system (scanning means) is moved to read the original. In the former sheet-through method, the optical system in the image reading apparatus is scanned and moved while being held at a predetermined image reading position. On the other hand, in the latter document fixing method, A reading operation is performed while the optical system scans and moves.

  In such an image reading apparatus capable of reading in the sheet-through method, a document guide is conventionally provided with a transport guide disposed above a contact glass. The conveyance guide also supports the reading guide at a position facing the image reading area, and after the document is guided along the conveyance guide, it passes through the gap between the reading guide and the contact glass. Then, the paper is guided further downstream by the conveyance guide and discharged to the document discharge tray.

  Such a gap is narrow so that the original does not float and be conveyed from the contact glass, and the conveyance load of the original is large. For this reason, it is necessary to increase the document conveying force. However, when the document conveyance force is increased, the conveyance state such as the document conveyance speed is likely to fluctuate, which may cause a problem in the read image. Further, the reading guide may be worn due to the conveyance of the document, and the image quality of the read image may be deteriorated.

  Therefore, Patent Document 1 discloses a document that has passed through the image reading region by providing a protrusion at a position downstream of the reading guide in the document conveying direction and facing the conveying guide provided below the reading guide from above. Discloses a technique for preventing a change in the conveyance state by preventing the ink from bulging upward.

  In Patent Document 2, a platen roller facing the platen glass, a platen holder (reading guide member) that rotatably supports the platen roller, and a platen holder are provided, and a gap is provided between the platen roller and the platen glass. Disclosed is a technology that stabilizes the luminance level of the reading unit and prevents image quality fluctuations by providing a regulating rib to be formed and configuring the platen roller and the platen holder to have a highly reflective surface property. Yes.

  Japanese Patent Application Laid-Open No. H10-228667 discloses that a document pressing roller is provided on the upstream side of the platen roller in the conveying direction of the platen holder to prevent the document from floating.

JP 2006-086957 A JP 2004-297780 A

  However, Patent Document 1 neither discloses nor suggests that a follower roller is provided for the reading guide. In addition, it is difficult to sufficiently reduce the document transport load even if the protrusion slides on the document. Further, in Patent Document 2, the driven roller is only provided on the upstream side in the document conveyance direction with respect to the surface facing the contact glass in the reading guide, and the document conveyance load may not be sufficiently reduced. Further, the arrangement of the driven roller is only disclosed on a fixed axis that penetrates the platen holder, that is, on a straight line.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a document transport device capable of reducing a transport load during document transport and suppressing variations in the transport state of the document, an image reading apparatus including the same, and an image forming apparatus. With the goal.

  In order to achieve the above object, the present invention can be opened and closed upward with respect to the contact glass, and is disposed to face the contact glass along the document transport direction, and guides the document to the upper surface of the contact glass. A conveyance guide member, which is disposed along the width direction of the document and is supported so as to be movable in the vertical direction with respect to the conveyance guide member, has a facing surface facing the image reading area, and contacts the document with the contact A document guide device having a reading guide member guided between the glass and the facing surface, wherein the document is respectively disposed upstream and downstream in the transport direction with the reading guide member interposed therebetween. The first and second conveyance roller pairs for conveying the image are provided, and are supported rotatably on the reading guide member on the upstream side in the conveyance direction of the facing surface. A plurality of first rotation members that are driven and rotated are provided in the width direction, and at least one of the first rotation members is different from the other rotation members in the conveyance direction. It is arranged at a position.

  According to the present invention, in the document conveying device having the above-described configuration, each of the first rotating members is closest to the upstream edge of the facing surface in the conveying direction and the first rotating member of the conveying guide member. It protrudes downward with respect to the 1st plane which connects a lower end edge, and this downward protrusion amount is substantially equal, It is characterized by the above-mentioned.

  The present invention also provides an image reading apparatus provided with the document conveying apparatus having the above-described configuration.

  The present invention also provides an image forming apparatus including the image reading apparatus having the above-described configuration.

  According to the first configuration of the present invention, the conveyance guide member is provided with the first and second conveyance roller pairs for conveying the document on the upstream side and the downstream side in the conveyance direction with the reading guide member interposed therebetween. The guide member is rotatably supported on the upstream side in the conveyance direction of the opposing surface, and a plurality of first rotation members that rotate following the document to be conveyed are provided in the width direction, and at least one rotation member of the first rotation members is provided. By disposing the rotating member at a position different from that of the other rotating members in the conveying direction, it is possible to reduce a conveying load caused by friction with the reading guide member when conveying the document.

  In addition, since the trailing edge of the document does not pass through the first rotating member in the width direction at the same time, the variation in document transportation load during the passage can be dispersed in the width direction, and the variation in document transportation speed can be reduced. Can be suppressed. As a result, it is possible to reduce the conveyance load during document conveyance and to suppress fluctuations in the document conveyance state.

  Further, according to the second configuration of the present invention, in the document conveying apparatus having the first configuration, the first rotating member is respectively connected to the upstream edge of the opposite surface in the conveying direction and the first of the conveying guide member. By projecting downward with respect to the first plane connecting the rotation member and the lower edge that is closest to the rotation member, and by making the downward projection amount substantially equal, the document is relative to each first rotation member. Since the press contact is performed with substantially the same press contact force, it is possible to further suppress fluctuations in the document conveyance state.

  Further, according to the third configuration of the present invention, the image reading device including the document transport device having the first or second configuration described above enables the image reading due to the variation in the transport load or the transport state of the document. The occurrence of defects can be prevented.

  Further, according to the fourth configuration of the present invention, an image forming apparatus including the image reading device having the third configuration described above causes an image reading defect due to a variation in the conveyance load or conveyance state of the document. And the occurrence of defects in the output image can be prevented.

1 is a side cross-sectional view illustrating an overall configuration of an image forming apparatus including a document conveying device according to an embodiment of the present invention. Side surface sectional view showing the internal structure around the document feeder according to the present embodiment Side sectional view showing the internal structure of the image reading apparatus on which the document conveying apparatus according to the present embodiment is placed. Side sectional view showing the configuration around the conveyance guide and the reading guide The perspective view which shows the support state of the reading guide with respect to a conveyance guide The perspective view which shows the arrangement | positioning state of a 1st driven roller and a 2nd driven roller from the downward direction Side surface sectional view showing the arrangement state of the first driven roller and the second driven roller Side view showing amount of protrusion of first driven roller from first plane S1 Side sectional view showing a state in which a document is conveyed

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus provided with a document conveying device according to an embodiment of the present invention. In FIG. 1, in the image forming apparatus 100 (here, a digital multi-function peripheral is shown as an example), when performing a copying operation, image data of a document is read and converted into an image signal by an image reading apparatus 6 described later. On the other hand, in the image forming unit 3 in the MFP main body 2, the photosensitive drum 5 rotating in the direction A in the figure is uniformly charged by the charging unit 4, and is based on the document image data read by the image reading device 6. An electrostatic latent image is formed on the photosensitive drum 5 by a laser beam from an exposure unit (laser scanning unit or the like) 7, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 8. An image is formed. The toner is supplied to the developing unit 8 from the toner container 9.

  The sheet is conveyed from the sheet feeding mechanism 10 to the image forming unit 3 via the sheet conveying path 11 and the registration roller pair 12 toward the photosensitive drum 5 on which the toner image is formed as described above. 3, the toner image on the surface of the photosensitive drum 5 is transferred to the sheet by the transfer roller 13 (image transfer unit). The sheet onto which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to a fixing unit 14 having a fixing roller pair 14a to fix the toner image. The paper that has passed through the fixing unit 14 is sent to a paper conveyance path 15 that branches in a plurality of directions, and is fed by a path switching mechanism 21, 22 having a plurality of path switching guides provided at branch points of the paper conveyance path 15. The transport directions are sorted, and the sheets are discharged as they are (or after being sent to the sheet transport path 16 and double-sided copying) to the sheet discharge section including the first discharge tray 17a and the second discharge tray 17b.

  Although not shown, a static elimination device that removes residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 18. Further, the paper feed mechanism 10 is detachably attached to the multifunction machine main body 2 and includes a plurality of paper feed cassettes 10a and 10b for storing paper, and a stack bypass (manual feed tray) 10c provided above the paper feed cassettes 10a and 10b. These are connected to the image forming unit 3 including the photosensitive drum 5 and the developing unit 8 by the paper transport path 11.

  An image reading device 6 is disposed on the upper portion of the apparatus main body, and a platen (document pressing member) that holds and holds a document placed on the contact glass 25 (see FIG. 2) of the image reading device 6 on the upper surface of the apparatus main body. ) 24 is provided so as to be openable and closable, and a document conveying device 27 is provided on the platen 24.

  Specifically, the sheet conveyance path 15 first branches into a left and right fork on the downstream side of the fixing roller pair 14a, and one path (a path branched in the right direction in FIG. 1) communicates with the first discharge tray 17a. It is configured as follows. The other path (the path that branches in the left direction in FIG. 1) is bifurcated via the conveying roller pair 19, and the other path (the path that branches in the left direction in FIG. 1) is the second discharge tray 17b. It is comprised so that it may communicate with. On the other hand, the other path (the path that branches downward in FIG. 1) is configured to communicate with the sheet conveyance path 16.

  FIG. 2 is a side sectional view showing the internal structure around the document conveying apparatus according to the present embodiment. The document transport device 27 includes a document feed tray 29 provided with a document guide 29 a for aligning and stacking a plurality of documents, and a reversing tray 30 provided below the document feed tray 29. Each member of the paper tray 29 and the reverse tray 30 is attached to the frame of the document conveying device 27. Further, a cover member 31 is supported so as to be openable and closable with one end (lower left in the figure) as a rotation fulcrum with respect to the frame of the document conveying device 27. It is formed directly on a part of the upper surface. A document transport path d from the document feed tray 29 to the document discharge tray 32 is formed in the cover member 31. By opening the cover member 31, the document transport path d is opened, and jamming can be performed. ing.

  In the cover member 31, along the document transport path d, a pickup roller 33, a paper feed belt 34 and a separation roller 35, a registration roller pair 36, a first transport roller pair (first transport roller pair) 38, and a second transport A document conveying member including a roller pair (second conveying roller pair) 39, a third conveying roller pair 40, a reverse roller pair 42, a discharge roller pair 43, and the like is provided. The paper feed belt 34 is wound around a driving roller 44a and a driven roller 44b, and a separation roller 35 is in contact with the roller at a predetermined pressure from below. The separation roller 35 has a built-in torque limiter, which rotates in the opposite direction to the paper feed belt 34 only when the rotational load is lower than a predetermined torque, and is driven to rotate with the paper feed belt 34 when the rotational load exceeds a predetermined torque. It is supposed to be. Above the pickup roller 33, an upper surface detection sensor 50 for detecting the upper surface position of the document is disposed.

  The contact glass 25 includes an automatic reading glass 25a and a manually placed original glass 25b. The document conveyance path d is curved so as to be reversed between the registration roller pair 36 and the automatic reading glass 25a. A plurality of paper detection sensors including a paper feed sensor Sa and a discharge sensor Sb for detecting the presence / absence or passage of a document are provided at appropriate positions on the document transport path d.

  Next, a sheet-through type document conveying operation using the document conveying device 27 will be described. In the sheet-through method, when a plurality of documents are set on the document feed tray 29 with the image surface facing upward, when a copy start button on an operation panel (not shown) of the image forming apparatus 100 is turned on, the lifting mechanism The lift plate 45 raised by (not shown) pushes up the pickup roller 33 through the document, and the weight of the frame (not shown) including the pickup roller 33 is added to the lift plate 45, so that the upper surface of the document is It is pressed against the pickup roller 33 with a predetermined pressure (paper feed pressure).

  Here, the pickup roller 33, the drive roller 44a, the driven roller 44b, and the paper feed belt 34 are arranged in a frame not shown. The pickup roller 33 is connected to a driving roller 44a by a gear (not shown). When the driving roller 44a is rotated by a roller driving motor (not shown), the pickup roller 33 is stretched by the driving roller 44a and the driven roller 44b. The paper belt 34 is driven to rotate, and the pickup roller 33 is also driven to rotate.

  The document set on the document feed tray 29 is usually fed to the nip portion between the feed belt 34 and the separation roller 35 by a pickup roller 33. Only the uppermost one of the plurality of documents is separated by the separation roller 35 and conveyed toward the registration roller pair 36. At that time, after the leading edge of the document is detected by the sheet feeding sensor Sa, the document is conveyed by a predetermined distance, and then the rotation driving of the pickup roller 33 and the sheet feeding belt 34 is stopped by stopping the operation of the roller driving motor. Paper feeding ends. The document that has been primarily fed is stopped in a state where the leading end of the document is bent at the nip portion of the registration roller pair 36.

  Secondary feeding is started after a predetermined time has elapsed since the completion of primary feeding. That is, the registration roller pair 36 is rotationally driven by the operation of a secondary paper feed drive motor (not shown). The original is conveyed by the registration roller pair 36, the first conveyance roller pair 38, and the second conveyance roller pair 39 through the automatic reading glass 25a toward the discharge roller pair 43, and finally the discharge roller pair 43. Are discharged onto the document discharge tray 32. At that time, the completion of image reading of one original is detected by detecting the passage of the rear end of the original by the discharge sensor Sb.

  Here, the discharge sensor Sb has a count function for counting the number of documents every time the document conveyance is completed. If the paper feed sensor Sa detects a subsequent document, the second and subsequent document conveyance is performed as described above. Will continue as well. The original is guided by a conveyance guide (conveyance guide member) 71 when passing through the automatic reading glass 25a, and passes through a gap between the reading guide (reading guide member) 73 and the automatic reading glass 25a. The image is conveyed while being lightly pressed toward the automatic reading glass 25a from above, and the image of the original is read by the image reading device 6 (see FIG. 1) through the automatic reading glass 25a. Details of the conveyance guide 71 and the reading guide 73 will be described later.

  When reading a double-sided document, for example, after reading an image on the surface of the document with the automatic reading glass 25a, the document is distributed to the reversing tray 30 by the branching claws 47a, 47b and 47c, and the reversing roller pair 42 is reversed. Thus, a two-stage reading method can be used in which the document is conveyed again to the upstream side of the registration roller pair 36 with the back side of the document facing up, and the image on the back side of the document is read by the automatic reading glass 25a.

  When the two-stage reading method is used, when the original after reading is sequentially discharged to the original discharge tray 32 as it is, the discharged original is stacked with the reverse side of the state set on the original feed tray 29. It will be. Therefore, after reading the image on the back side of the document with the automatic reading glass 25a, the branching claws 47a to 47c are swung to introduce the document again onto the reverse tray 30, and the third conveying roller pair 40 and the discharge roller pair 43 are moved. To the document discharge tray 32. As a result, the front and back of each document are reversed again before being discharged, so that they can be stacked on the document discharge tray 32 while maintaining the state of being set on the document feed tray 29.

  Next, the configuration of the image reading device 6 for reading an image of a document as an electric signal will be described. FIG. 3 is a side sectional view showing the internal structure of the image reading apparatus according to this embodiment. In the frame 6a of the image reading device 6, a lamp (light source) 61 that irradiates light toward the image surface of the document, and a reflecting plate 62 for efficiently applying light from the lamp 61 to the image surface of the document. The first mirror 63 that directly receives and reflects the original reflected light, the second mirror 64 that receives and reflects the reflected light from the first mirror 63, and the reflected light that is received from the second mirror 64 and reflected. A third mirror 65 is disposed.

  Further, a lens barrel 66 holding a lens group (not shown) for introducing and collecting the reflected light from the third mirror 65, and the original reflected light collected by the lens group of the lens barrel 66 are received. A line-type CCD (photoelectric conversion member) sensor (image reading unit) 67 including a photoelectric conversion element that converts an electric signal is disposed on the base plate 70. The optical path of the original reflected light is indicated by a one-dot chain line.

  Here, the lamp 61, the reflector 62 and the first mirror 63 are integrally fixed on the first carriage 68, and the second mirror 64 and the third mirror 65 are integrally fixed on the second carriage 69. ing. These first and second carriages 68 and 69 constitute scanning means and are reciprocally movable in cooperation with each other although they are independent of each other.

  That is, when the original image reading operation is performed by the sheet through method, the first carriage 68 is moved and held immediately below the first image reading region (image reading region) R1 of the automatic reading glass 25a. At the same time, the second carriage 69 is held at a predetermined position. On the other hand, in the original fixing method, the first carriage 68 and the second carriage 69 maintain the optical path length of the original reflected light with respect to each other for a manually placed original. The glass 25b is reciprocated (scanned) below the second image reading region R2. The first carriage 68 and the second carriage 69 are driven by a carriage drive motor (not shown).

  Under such a configuration, the document reflected light irradiated from the lamp 61 and reflected by the image surface of the document is reflected by the first mirror 63 to the third mirror 65 and introduced into the lens group in the lens barrel 66. The light is condensed by the lens group and formed on the CCD sensor 67. The CCD sensor 67 performs photoelectric conversion processing, and the document image is read as an electrical signal.

  FIG. 4 is a side cross-sectional view illustrating a configuration around the conveyance guide and the reading guide, and FIG. 5 is a perspective view illustrating a supporting state of the reading guide with respect to the conveyance guide. Portions common to those in FIG. 2 are denoted by common reference numerals and description thereof is omitted.

  As shown in FIG. 4, a first drive roller 38 a constituting the first transport roller pair 38 is disposed at the upstream end portion of the transport guide 71 in the document transport direction (arrow direction in the figure), and at the downstream end portion. The second drive roller 39a constituting the second transport roller pair 39 is disposed. The first driven roller 38b is pressed against the first drive roller 38a to form a first nip portion N1 (see FIG. 7), and the second driven roller 39b is pressed to the second drive roller 39a to A second nip portion (nip portion) N2 (see FIG. 7) is formed.

  A central portion in the document conveyance direction at the lower end of the conveyance guide 71 is recessed upward along the front-rear direction of the apparatus main body (the width direction of the document, the direction perpendicular to the paper surface of FIG. 4). 73 is arranged along the conveyance guide 71. Further, the first driven roller (first rotating member) 77 is provided upstream of the facing surface 73d of the reading guide 73 facing the first image reading region R1 (see FIG. 2), and the second driven roller is provided downstream. A (second rotating member) 78 is provided. Details of the first and second driven rollers 77 and 78 will be described later.

  The document transported from the registration roller pair 36 is transported on the document transport path d by the first transport roller pair 38, guided to the first driven roller 77 on the upstream side of the reading guide 73, and the facing surface 73 d of the reading guide 73. And the automatic reading glass 25a. After passing through the gap, the document is guided to the second driven roller 78 on the downstream side, and conveyed by the second conveying roller pair 39 to the discharge roller pair 43 (see FIG. 2).

  As shown in FIG. 5, at the front side (front side in the figure) end of the conveyance guide 71, a plate-like shape that protrudes to the front side along the document conveyance direction (arrow direction in the figure) is located above the reading guide 73. A support portion 71a is formed. Two elastic portions 71b made of an elastic material projecting downward are formed on the support portion 71a along the document conveying direction.

  The elastic part 71b is formed at a position sandwiching a protruding part 73a described later, and a claw part 71c that protrudes inwardly between the elastic parts 71b and is pointed downward is formed at the tip of the elastic part 71b. Has been. Each of the claw portions 71c is provided with a first inclined portion 71ca that is inclined inward and upward. In addition, a substantially cylindrical guide portion 71d protruding downward is formed between the elastic portions 71b in the support portion 71a.

  On the other hand, at the front side end of the reading guide 73, a plate-like shape that protrudes to the front side along the document conveyance direction at a position below the support portion 71a of the conveyance guide 71 and sandwiched between the two elastic portions 71b. The protrusion 73a is formed. Both ends of the protruding portion 73a in the document conveying direction are slidable with the elastic portion 71b, and the protruding portion 73a is formed with a through hole 73aa through which the guide portion 71d is slidably penetrated. Thus, the protruding portion 73a is slidably held by the elastic portion 71b while being guided by the guide portion 71d. In addition, since the protrusion part 73a is guided by sliding with the guide part 71d and the through-hole 73aa, it can also be set as the structure clamped so that the protrusion part 73a can move without sliding with respect to the elastic part 71b. .

  When both ends of the projecting portion 73a in the document conveying direction are pressed against the claw portion 71c from below, the both end portions press the claw portion 71c outward, and the elastic portion 71b is bent by the pressing. Thereby, the protrusion part 73a is arrange | positioned above the nail | claw part 71c, and after arrange | positioning above this, the downward movement is controlled by the nail | claw part 71c. Thus, the protrusion 73a is engaged with the elastic part 71b by a snap fit.

  In addition, when the protrusion part 73a is arrange | positioned upwards rather than the nail | claw part 71c, the protrusion part 73a is slidably clamped by the elastic part 71b as above-mentioned. Moreover, the 2nd inclination part 73ab which can be engaged with the 1st inclination part 71ca protrudes in the both ends facing the claw part 71c of the protrusion part 73a toward the downward direction, and the protrusion part 73a is a nail | claw part. When contacting 71c from above, the first inclined portion 71ca and the second inclined portion 73ab are engaged.

  A reinforcing portion 73b is projected from the protruding portion 73a downward. The reinforcing portion 73b protrudes downward from the protruding portion 73a and protrudes from the front side end of the reading guide 73 to the front side. Thereby, durability with respect to the impact at the time of engagement with the protrusion part 73a and the nail | claw part 71c can be improved.

  A coil spring 75 is disposed between the support portion 71a and the protruding portion 73a so as to surround the peripheral surface of the guide portion 71d along the vertical direction. By the coil spring 75, the protruding portion 73a is urged in a direction away from the support portion 71a (downward). The biasing force of the coil spring 75 is closed when the document conveying device 27 is opened with respect to the contact glass 25 (see FIG. 1), and the protruding portion 73a engages with the claw portion 71c to restrict its downward movement. At this time, the force is set so that the reading guide 73 and the conveyance guide 71 do not contact each other in the vertical direction.

  In addition, protrusions 73 c are provided so as to protrude downward at the front and back end portions of the facing surface 73 d of the reading guide 73. Accordingly, when the document conveying device 27 is closed with respect to the contact glass 25, the projection 73c and the automatic reading glass 25a come into contact with each other, and the facing surface 73d of the reading guide 73 and the automatic reading glass 25a (see FIG. 4). The interval can be made constant.

  Note that an engagement projection (not shown) is formed at the rear side end of the reading guide 73, and the engagement projection is engaged with an engagement hole (not shown) formed at the rear side end of the conveyance guide 71. In this engaged state, the engaging protrusion can move up and down with respect to the engaging hole and is separated from the engaging portion by a coil spring (not shown). Being energized by.

  First, the engagement protrusion (not shown) formed at the rear side end of the reading guide 73 is engaged with the engagement hole (not shown) formed in the conveyance guide 71. Next, when the coil spring 75 is inserted so as to surround the peripheral surface of the guide portion 71 d and the front side end portion of the reading guide 73 is moved upward from below the front side end portion of the conveyance guide 71, the protruding portion 73 a becomes an elastic portion. The guide part 71d penetrates the through-hole 73aa of the protrusion part 73a while engaging with 71b by snap fit.

  Thus, the protruding portion 73a is slidably held between the elastic portions 71b, and the reading guide 73 can be slidably fixed to the conveyance guide 71 and assembled. In this way, since the reading guide 73 is assembled to the conveyance guide 71, it is possible to reduce the number of parts and to omit the assembly.

  When the document feeder 27 (see FIG. 1) is closed, the protrusion 73c comes into contact with the automatic reading glass 25a (see FIG. 4), and the downward movement of the reading guide 73 is restricted. At this time, since the reading guide 73 and the conveyance guide 71 approach each other in the vertical direction, the protruding portion 73a is disposed above the claw portion 71c below the support portion 71a.

  On the other hand, when the document conveying device 27 (see FIG. 1) is opened, the reading guide 73 moves downward by the biasing force of the coil spring 75 and the weight of the reading guide 73, but the protruding portion 73a engages with the claw portion 71c. Therefore, the downward movement of the reading guide 73 is restricted. At this time, since the second inclined portion 73ab of the protruding portion 73a and the first inclined portion 71ca of the claw portion 71c are engaged, the downward movement of the reading guide 73a is more reliably restricted. Further, this engagement can prevent assembly failure over time.

  Next, the arrangement of the first driven roller 77 and the second driven roller 78 will be described. 6 is a perspective view showing the arrangement state of the first driven roller and the second driven roller from below, and FIG. 7 is a side sectional view showing the arrangement state of the first driven roller and the second driven roller. 8 is a side view showing the amount of protrusion of the first driven roller from the first plane S1. Portions common to FIGS. 4 and 5 are denoted by common reference numerals and description thereof is omitted.

  As shown in FIG. 6, in the reading guide 73, on the upstream side in the document conveyance direction (arrow direction in the figure) across the facing surface 73d, the direction perpendicular to the document conveyance direction (the document width direction, the vertical direction in the figure). Three first driven rollers 77a, 77b and 77c are arranged in order from the front side (upper side in the figure) to the rear side (lower side in the figure), and in the width direction on the downstream side in the document transport direction. Three second driven rollers 78a, 78b and 78c are arranged in order from the front side to the back side.

  Of the first driven rollers 77a to 77c, the first driven roller 77a on the foremost side and the first driven roller 77c on the backmost side are arranged on the straight line L1 along the width direction and arranged in the center. The first driven roller 77b is disposed downstream of the first driven rollers 77a and 77c. As a result, when the trailing edge of the original passes through the first driven rollers 77a to 77c, the first driven rollers 77a to 77c do not simultaneously pass in the width direction. It is possible to suppress fluctuations in the conveyance speed by dispersing in the direction.

  As shown in FIGS. 7 and 8, the first driven rollers 77 a to 77 c all have circumferential surfaces 73 a on the upstream side 73 d in the document conveying direction of the opposing surface 73 d and the first driven rollers of the conveying guide 71. 77a-77c protrudes below the 1st plane (1st plane) S1 which ties the lower end edge 71e which comes closest. Further, the protruding amount D (that is, the amount of contact with the original) of the peripheral surfaces of the first driven rollers 77a to 77c with respect to the first plane S1 is set to be substantially equal.

  As a result, the first driven rollers 77a to 77c are rotated following the original conveyed upstream of the facing surface 73d, so that the original conveyance load can be reduced. In addition, since the document is pressed against each of the first driven rollers 77a to 77c with substantially the same pressing force, fluctuations in the transport state of the document can be further suppressed.

  On the other hand, the second driven rollers 78a to 78c are all arranged on the straight line L2 along the width direction. Further, the peripheral surfaces of the second driven rollers 78a to 78c connect a second flat surface (second surface) connecting the downstream edge 73db of the opposing surface 73d in the document conveying direction and the second nip portion N2 of the second conveying roller pair 39. The second driven rollers 78a to 78c are arranged so as to overlap S2.

  As a result, the second driven rollers 78a to 78c are rotated following the original conveyed downstream of the facing surface 73d, so that the original conveyance load can be reduced. The amount of overlap between the peripheral surface of the second driven rollers 78a to 78c and the second plane S2, that is, the amount of protrusion of the peripheral surface with respect to the second plane S2 is determined by the rotation of the second driven rollers 78a to 78c. The load can be reduced, and can be appropriately set to such an extent that the load is not increased due to being caught by the second driven rollers 78a to 78c.

  Further, when the trailing edge of the original passes through the second driven rollers 78a to 78c, since the original passes through the first image reading region R1 (see FIG. 2), the second driven rollers 78a to 78c are moved. There is no particular need to dispose them at different positions in the transport direction. However, it can also be arranged shifted in the transport direction according to the document transport state or the like.

  Next, the document conveyance state will be described. FIG. 9 is a side sectional view showing a state in which the document is conveyed. Portions common to FIGS. 5 to 7 are denoted by common reference numerals, and description thereof is omitted. As shown in FIG. 9, when the original enters the first nip portion N1 of the first conveying roller pair 38, the original is conveyed downstream by the first conveying roller pair 38 and further guided by the first driven rollers 77a to 77c. The second nip portion of the second conveying roller pair 39 is guided by the second driven rollers 78a to 78c after passing through the gap between the facing surface 73d of the reading guide 73 and the automatic reading glass 25a. N2 is entered and conveyed to the discharge roller 43 by the second conveying roller pair 39.

  At this time, normally, the transport speed (rotational speed) of the second transport roller pair 39 is set to be higher than the transport speed of the first transport roller pair 38, so that the downstream edge 73db of the facing surface 73d A greater tension is applied to the document between the second nip portion N2 and between the upstream end edge 73da of the facing surface 73d and the first nip portion N1.

  However, since the second driven rollers 78a to 78c are provided here, the conveyance load between the downstream end edge 73db of the facing surface 73d and the second nip portion N2 can be reduced. Further, since the first driven rollers 77a to 77c are provided, it is possible to avoid the rear end of the original from passing the first driven rollers 77a to 77c in the width direction at the same time, and to suppress fluctuations in the conveyance speed of the original. Can do.

  In addition, since the protruding amounts of the peripheral surfaces of the first driven rollers 77a to 77c with respect to the first plane S1 are substantially equal between the upstream end edge 73da of the facing surface 73d and the first nip portion N1, they are pressed against the document. The forces can be made approximately equal.

  As described above, the conveyance guide 71 includes the first and second conveyance roller pairs 38 and 39 for conveying the document on the upstream side and the downstream side in the conveyance direction with the reading guide 73 interposed therebetween. A plurality of first and second driven rollers 77 and 78 that are rotatably supported on the upstream side and the downstream side in the document conveyance direction with the 73d interposed therebetween and that rotate following the document to be conveyed are provided in the width direction of the document. Among the driven rollers 77a to 77c, the first driven roller 77b is disposed at a position different from the other first driven rollers 77a and 77c in the document transport direction, and therefore, a transport load caused by friction with the reading guide 73 during document transport is reduced. Can be reduced.

  In addition, since the trailing edge of the original does not pass through the first driven rollers 77a to 77c in the width direction at the same time, fluctuations in the conveyance load of the original during the passage can be dispersed in the width direction. Variations can be suppressed. As a result, it is possible to reduce the conveyance load during document conveyance and to suppress fluctuations in the document conveyance state.

  In the present embodiment, the first driven roller 77b is arranged at a position different from the first driven rollers 77a and 77c in the document conveying direction. However, at least one of the first driven rollers 77a to 77c may be replaced with other ones. If the arrangement is different from the following driven rollers, it is possible to prevent the rear end of the document from passing through the first driven rollers 77a to 77c simultaneously in the width direction. Accordingly, the arrangement and quantity of the first driven rollers 77a to 77c are not particularly limited as long as the first driven rollers 77a to 77c are arranged at different positions in the document conveyance direction.

  Further, such an arrangement can be appropriately set according to the passage position of the document in the width direction (direction perpendicular to the document conveyance direction) in the first image reading region R1 (see FIG. 2). As shown in the present embodiment, the first driven roller 77b can be arranged at a position different from the others. Further, such an arrangement can be appropriately set according to the document conveyance state and the like. Further, for example, in the above-described embodiment, the number of the first driven rollers 77a to 77c may be two or more, and can be appropriately set according to the size of the document or the document transport device 27, and the like.

  In the present embodiment, the first driven rollers 77a to 77c are respectively connected to the upstream edge 73da in the document conveying direction of the facing surface 73d and the lower edge 71e closest to the first driven rollers 77a to 77c of the conveying guide 71. Are projected downward with respect to the first plane S1 and the amount of projection relative to the first plane S1 is substantially equal, so that the document is pressed against each of the first driven rollers 77a to 77c with substantially the same pressing force. The Thereby, it is possible to further suppress fluctuations in the conveyance state of the document. However, the protruding amount can be set as appropriate according to the conveyance state of the document, and can be different for each of the first driven rollers 77a to 77c.

  In the present embodiment, the second driven rollers 78a to 78c are arranged along the width direction, and the peripheral surfaces of the second driven rollers 78a to 78c are opposite to the downstream edge 73db in the document conveying direction of the facing surface 73d. Since the second conveyance roller pair 39 is disposed at a position overlapping the second plane S2 connecting the second nip portion N2 of the second conveyance roller pair 39, the document conveyance load can be further reduced and fluctuations in the document conveyance state can be further suppressed. .

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. The conveyance guide 71 and the reading guide 73 used in the above embodiment, the assembled state thereof, and the like are not particularly limited, and can be appropriately set according to the apparatus configuration and the like.

  In the above embodiment, the image reading device 6 is a unit in which the pickup roller 33 and the paper feed belt 34 are unitized. However, the pickup roller 33 may be provided separately from the paper feed belt 34. A configuration in which a paper feed roller is disposed in place of the paper feed belt 34 and a configuration in which a separation pad is disposed in place of the separation roller 35 are also possible.

  According to the present invention, first and second pairs of conveyance rollers for conveying a document are provided on the conveyance guide member on the upstream side and the downstream side, respectively, in the conveyance direction with the reading guide member interposed therebetween. A plurality of first rotating members that are rotatably supported on the upstream side in the conveying direction and are rotated in a driven direction with the original to be conveyed are provided in the width direction, and at least one of the first rotating members is another rotating member. Is a document conveying device arranged at a different position in the conveying direction.

  As a result, it is possible to reduce the conveyance load during document conveyance and to suppress fluctuations in the document conveyance state. Further, by using the image reading apparatus and the image forming apparatus provided with the document conveying device, it is possible to prevent the occurrence of an image reading defect due to a variation in the document conveying load and the conveying state and the occurrence of a defect in the output image. be able to.

6 Image Reading Device 25 Contact Glass 25a Automatic Reading Glass 25b Manual Placed Glass 27 Document Conveying Device 38 First Conveying Roller (First Conveying Roller)
39 Second transport roller (second transport roller)
71 Conveyance guide (conveyance guide member)
71e Lower edge 73 Reading guide (reading guide member)
73d Opposing surfaces 77a to 77c First driven roller (first rotating member)
78a to 78c second driven roller (second rotating member)
75 Coil spring 100 Image forming apparatus N1 First nip portion N2 Second nip portion (nip portion)
R1 first image reading area (image reading area)
R2 Second image reading area S1 First plane (first plane)
S2 Second plane (second plane)

Claims (4)

The contact glass can be opened and closed upward,
A conveyance guide member that is arranged to face the contact glass along the conveyance direction of the document and guides the document to the upper surface of the contact glass;
It is disposed along the width direction of the document and is supported so as to be movable in the vertical direction with respect to the transport guide member, and has a facing surface that faces the image reading area, and the document is placed on the contact glass and the facing surface. A document guide device having a reading guide member guided between
First and second pairs of transport rollers for transporting the document are provided on the transport guide member on the upstream and downstream sides in the transport direction with the reading guide member interposed therebetween, respectively.
A plurality of first rotation members that are rotatably supported by the reading guide member on the upstream side in the conveyance direction of the facing surface and that rotate following the document to be conveyed are provided in the width direction;
At least one rotating member among the first rotating members is arranged at a position different from the other rotating members in the conveying direction.   Each of the first rotating members is connected to a first plane connecting the upstream end edge of the facing surface in the transport direction and a lower end edge of the transport guide member that is closest to the first rotating member. The document conveying apparatus according to claim 1, wherein the document conveying device projects downward, and the amount of downward projection is substantially equal.   An image reading apparatus comprising the document conveying device according to claim 1.   An image forming apparatus comprising the image reading apparatus according to claim 3.