JP2010052852A - Document conveyance device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convey a document to be read in such a state that the document is not twisted or wrinkled, while securing appropriate reading of a document image. <P>SOLUTION: The document conveyance device includes: an image reading part making a predetermined image reading device 17 read the document image, by passing the document P0 between a glass 180b for automatic reading and a reading guide 40 disposed above the glass and to be opposed to the glass; a paper passage 50 formed downstream of the document reading part and passing the document P0 after the image is read therefrom; a pre-guide roller 60 disposed on an upper face side of the paper passage 50; and a plurality of conveyance roller pairs 70 constituting of a plurality of upper guide rollers 71 disposed downstream of the pre-guide roller 60 and in parallel with one another in a document width direction, and a plurality of lower guide rollers 72 disposed to be in parallel with one another so that their circumferential faces abut on circumferential faces of the upper guide rollers 71. The lower guide roller 72 at the center part out of the plurality of lower guide rollers 72 is disposed closer to the pre-guide roller 60 than other lower guide rollers 72. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a document conveying device that conveys a document having image information toward a reading position of the image information, and an image forming apparatus including the document conveying device.

  2. Description of the Related Art An image forming apparatus such as a copying machine or a facsimile machine that presupposes reading of a document image includes a document transporting device that transports a document fed one by one from a document bundle on a document tray toward a document reading position. Is provided. At the document reading position, a contact glass and a reading guide member having a V shape in a side view disposed opposite to the contact glass are provided, and the reading guide members are respectively upstream and downstream of the contact glass. Are provided with an upstream roller pair and a downstream roller pair. Generally, a plurality of these roller pairs are concentrically arranged in parallel on an axis extending in the document width direction orthogonal to the document conveyance direction.

  Then, the original conveyed from the original tray is fed downward toward the contact glass by the driving of the upstream roller pair, and passes through the gap between the reading guide member and the contact glass. The image is scanned and read by reflected light of light irradiated from below the contact glass. The document that has passed over the contact glass is conveyed by a pair of downstream rollers and discharged to a sheet discharge tray.

  In such a document conveying device, the document that has passed over the contact glass reaches the plurality of downstream roller pairs with the leading edge thereof reaching a plurality of downstream roller pairs in a state where the document is slightly loosened on the downstream side of the contact glass. Because the paper is nipped all at once by the pair of side rollers, the tension does not act on the original until it sags after it is nipped, and this slows the speed of transporting the original on the contact glass until the tension is restored. Occurs. If the transport speed of the document passing through the contact glass changes, there arises a disadvantage that the document image cannot be read properly.

  In order to eliminate such inconvenience, in the document conveying apparatus described in Patent Document 1, the nip positions of a plurality of downstream roller pairs are shifted in the conveying direction. Specifically, as shown in FIGS. 3 and 4 of Patent Document 1, the position of the nip of the downstream roller pair at one end in the width direction is set to the position closest to the contact glass, and the other The nip position is gradually shifted toward the downstream side toward the end.

By doing so, the originals after passing through the contact glass are not simultaneously nipped by a plurality of pairs of downstream rollers, but are sequentially nipped from the end one by one. The speed reduction can be avoided, thereby reducing the occurrence of abnormal images.
JP 2004-277055 A

  By the way, in the document conveying device of Patent Document 1, the nip position of one end in the width direction among the plurality of downstream roller pairs arranged side by side is set to the position closest to the contact glass. Since the nip position is shifted slightly toward the downstream side toward the other end, the original that has passed through the contact glass is first nipped by the pair of downstream rollers at the end. It will be. When one end portion of the document is nipped and pulled at the time of the nip, there is a problem that a problem that a twist occurs or a wrinkle easily occurs due to a moment acting on the document.

  The present invention has been made to solve such problems, and performs document conveyance for reading in a state in which the document image can be read properly and is not twisted or wrinkled. An object of the present invention is to provide a document conveying device capable of performing the above and an image forming apparatus including the document conveying device.

  According to a first aspect of the present invention (original conveying apparatus), an image reading unit that reads an image of an original fed one by one from a bundle of originals, and an image reading unit formed downstream of the original reading unit in the original conveying direction. A paper path through which the original passes, a pre-guide roller disposed on the upper surface side of the paper path, and a plurality of upper guide rollers and a circumference arranged in parallel in the document width direction on the downstream side of the pre-guide roller Including a plurality of conveying roller pairs composed of a plurality of lower guide rollers arranged in parallel so that a surface abuts on a peripheral surface of the upper guide roller, and a central portion in the document width direction of the plurality of lower guide rollers Is provided at a position closer to the pre-guide roller than the others.

  According to such a configuration, the document fed from the sheet bundle to the document reading unit is read by the document reading unit, and subsequently guided to the pre-guide roller through the sheet path, and then the leading edge is It reaches the nip portion between the lower guide roller at the center and the upper guide roller at the center (that is, the nip portion of the pair of transport rollers at the center).

  Thereafter, the document conveyed by the driving rotation of the upper and lower guide rollers sequentially reaches the nip portion of the upper and lower guide rollers other than the central portion (that is, the nip portion of the conveying roller pair other than the central portion), The conveyance is continued by these driving rotations while being nipped by upper and lower guide rollers other than the central portion.

  As described above, since the document that has passed through the document reading unit is relayed by the pre-guide roller in the paper path from the document reading unit until it reaches the central conveyance roller pair, the pre-guide roller The pre-guide roller suppresses the flickering phenomenon at the leading edge of the document that has occurred when no is present. Therefore, when the pre-guide roller is not provided, it is possible to effectively suppress the occurrence of inconvenience that the document is unstable at the leading edge and the conveyance state in the document reading unit becomes unstable and proper image reading processing cannot be performed. Is done.

  In addition, the document whose document image has been read by the document reading unit is relayed and conveyed by the rotation of the pre-guide roller, and then nipped by the conveyance roller pair at the center in the document width direction, and continues to be conveyed. There is no moment in the document width direction orthogonal to the conveyance direction, and as a result, it is possible to effectively prevent the occurrence of inconveniences such as wrinkles on the document or distortion of the read image due to oblique conveyance. .

  Then, since the original conveyed by a pair of conveying rollers at a proper distance for a short distance is immediately conveyed by a plurality of other conveying roller pairs, it is discharged outside in a stable state.

  According to a second aspect of the present invention, in the first aspect of the present invention, the conveying roller pair is positioned on the most upstream side in the central portion, and gradually positioned on the downstream side toward the end in the document width direction. It is characterized by being set.

  According to such a configuration, the document whose nipped center position of the leading edge is nipped by the central conveyance roller pair is endured from the conveyance roller pair near the center in a symmetrical state as the conveyance roller is driven. Since the nips are sequentially niped toward the transport roller pairs closer to each other, the transport force of each transport roller pair is always applied equally to the left and right with respect to the center line extending in the transport direction. As a result, the document is extremely stable. In this state, the conveyance is continued and discharged to the outside.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a lower roller unit for supporting the plurality of lower guide rollers is provided, and the lower roller unit includes a lower guide roller for each lower guide roller. A plurality of roller holders rotatably supported around an axis; a base plate supporting the plurality of roller holders; a plurality of pairs of brackets arranged in parallel to mount the plurality of roller holders on the base plate; and the lower guide rollers. And a biasing member that biases the roller holder so that the peripheral surfaces of the upper guide rollers are in contact with the corresponding peripheral surfaces, and the pair of brackets have elongated holes extending in the front-rear direction facing each other. Are formed in the roller holder, the projecting shafts projecting in opposite directions from both side surfaces thereof, and the elongated hole. That the position fixing member to fix the position of the projecting shaft is provided with is characterized in.

  According to such a configuration, the position of the lower guide roller can be easily set via the roller holder by moving the protruding shaft forward and backward within the long hole. Then, the set position of the lower guide roller is fixed by fixing the position of the projecting shaft by the position fixing member in a state where the position is set.

  Therefore, compared to the case where the installation position of the lower guide roller is changed from the beginning as in the prior art, the position of the lower guide roller can be easily set by moving the projecting shaft within the long hole after attaching the lower guide roller. Fine adjustment of the position of the lower guide roller after attachment is easy, and the workability of the lower guide roller mounting operation and position adjustment operation can be greatly improved.

  Then, with the position of each lower guide roller set, each lower guide roller has its peripheral surface in close contact with the corresponding peripheral surface of the upper guide roller by the biasing force of the biasing member. The document that has reached the nip portion of the guide roller is reliably conveyed by the drive rotation of the upper guide roller.

  According to a fourth aspect of the present invention (an image forming apparatus), a predetermined image forming process is performed based on a document image conveyed by the document conveying device according to any one of the first to third aspects and read by a document reading unit. It is characterized by applying.

  According to such a configuration, the image forming apparatus can enjoy the function and effect of the document conveying device according to any one of claims 1 to 3.

  According to the document conveying device of the present invention, the document after the document image is read by the document reading unit is conveyed by the pre-guide roller until the document reaches the pair of conveyance rollers at the center from the document reading unit. Therefore, it is possible to appropriately perform the image reading process in a stable state while suppressing the flutter at the leading edge of the document, and it is possible to suppress the occurrence of image reading defects due to the flutter of the document.

  In addition, since the original on which the original image has been read by the original reading unit is relayed and conveyed by the driving rotation of the pre-guide roller, it is first nipped by the conveyance roller pair at the center and is continuously conveyed. A moment that does not come off does not occur, and as a result, it is possible to effectively prevent the occurrence of inconveniences such as wrinkles on the document or distortion of the read image due to oblique conveyance.

  According to the image forming apparatus of the present invention, the image forming apparatus can enjoy the function and effect of the document conveying apparatus according to any one of claims 1 to 3.

  First, an image forming apparatus to which the document conveying device according to the present invention is applied will be described. FIG. 1 is a front sectional view showing an embodiment of an internal structure of an image forming apparatus to which a document conveying device according to the present invention is applied. In FIG. 1, the X-X direction is referred to as the left-right direction, and in particular, -X is referred to as the left and + X is referred to as the right.

  As shown in FIG. 1, an image forming apparatus 10 is used as a copying machine, and is provided in an apparatus main body 11 having a box shape called an in-body discharge type, and an upper portion of the apparatus main body 11. And a basic configuration including an image reading unit 16 for reading a document image. The image reading unit 16 is configured by an image reading device 17 being formed inside an outer cover body 170 having a flat box shape, and an automatic document feeder 18 being attached to the upper portion of the outer cover body 170. Yes.

  In the apparatus main body 11, an image forming unit 12 that forms an image based on image information of a document read by the image reading device 17, and a fixing process for an image formed by the image forming unit 12 and transferred to the paper P The fixing unit 13 that performs the above and the paper storage unit 14 that stores the transfer paper P are internally provided. A paper discharge unit 15 including an in-body paper discharge tray 151 that receives the discharged paper P after fixing processing is provided at the top of the apparatus main body 11 and immediately below the image reading unit 16.

  The automatic document feeder 18 includes a document pressing cover 181 that covers a contact glass 180 fitted in the upper surface opening of the image reading device 17, a document feeding portion 182 formed on the upper left side of the document pressing cover 181, A document tray 183 is provided that protrudes obliquely upward from the right surface of the document feeding portion 182 to the right.

  The contact glass 180 is a book original glass 180a that has a rectangular shape in a plan view slightly smaller than the entire upper surface of the exterior cover body 170, and a current conveying direction adjacent to the left side of the book original glass 180a. It consists of a long automatic reading glass 180b that is oriented in the direction of the document width perpendicular to it. The book original glass 180a is for book originals and the like, and is used for manually placing the originals with the original surface facing down. On the other hand, the automatic reading glass 180b is for reading the original image of the original P0 for the original P0 fed out one by one from the original bundle placed on the original tray 183.

  The document pressing cover 181 holds the book document or the like placed on the book document glass 180a in a stable manner, and an image on the document surface is read by the image reading device 17 through the book document glass 180a. It is done. The document presser cover 181 opens and closes by rotating forward and backward about a predetermined axis provided on one side of the upper surface of the apparatus main body (in the case of FIG. 1, the back side of the paper).

  The document feeding section 182 feeds the documents one by one from the bundle of documents placed on the document tray 183 and supplies them to the automatic reading glass 180b for use in reading the document surface by the image reading device 17. is there. The document for which the document surface has been read is discharged onto the document pressing cover 181. The image information of the document read by the image reading unit 16 is output to the image forming unit 12 in a state of being converted into an electric signal. A document conveying device 20 (FIG. 2) according to the present invention is provided at a position below the document feeding portion 182 in the automatic document feeder 18.

  The image reading device 17 is provided with a box-shaped casing 171 and the casing 171 so as to be movable forward and backward in the left-right direction. A reading unit 172 and a CCD (Charge Coupled Device) unit 173 that collects reflected light from the reading unit 172 and captures it as image data are provided.

  Then, an image of the original surface of the original placed on the book original glass 180 a or supplied from the original tray 183 to the automatic reading glass 180 b via the original feeding unit 182 is irradiated from the reading unit 172. And is read as image information by the CCD unit 173. The read image information is output to an exposure device 124 described later after the analog information is converted into digital information.

  At an appropriate position of the image reading unit 16, an operation panel (not shown) for inputting processing conditions relating to document reading, copying processing, and the like is provided. The operation panel is provided with a display panel (not shown), a numeric keypad, a start button, a mode switching key, and the like.

  The image forming unit 12 forms a toner image on a sheet fed from the sheet storage unit 14, and in the present embodiment, for magenta arranged sequentially from the upstream side (right side) to the downstream side. A unit 12M, a cyan unit 12C, a yellow unit 12Y, and a black unit 12K are provided.

  Each unit 12M, 12C, 12Y, 12K is provided with a photosensitive drum 121, respectively. The photoconductive drum 121 rotates in the counterclockwise direction around the center of the drum and receives toner supply from the corresponding developing device 122 to form a toner image on the peripheral surface thereof. Each developing device 122 is replenished with toner from an unillustrated toner cartridge disposed on the front side of the apparatus main body 11 (the front side of the paper surface of FIG. 1).

  A charger 123 is provided immediately below each photoconductor drum 121, and an exposure device 124 is provided further below each charger 123. Each photosensitive drum 121 has a peripheral surface uniformly charged by the charger 123, and laser light corresponding to each color based on the image data input by the image reading unit 16 is emitted from the exposure device 124. The peripheral surface is irradiated. Thereby, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. By supplying toner from the developing device 122 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 121.

  A transfer belt 125 stretched between the driving roller 125a and the driven roller 125b is provided at a position above each photoconductive drum 121 so as to be in contact with the peripheral surface of each photoconductive drum 121. The transfer belt 125 is driven by a driving roller 125 a and a driven roller while being synchronized with each photosensitive drum 121 while being opposed to the peripheral surface of the photosensitive drum 121 by a transfer roller 126 provided corresponding to each photosensitive drum 121. Circulate between the rollers 125b.

  Accordingly, when the transfer belt 125 circulates, the magenta toner image is transferred onto the surface of the transfer belt 125 by the photosensitive drum 121 of the magenta unit 12M, and then the photosensitive drum of the cyan unit 12C is placed at the same position on the transfer belt 125. The transfer of the cyan toner image by 121 is performed in the overcoating state, and then the transfer of the yellow toner image by the photosensitive drum 121 of the yellow unit 12Y to the same position of the transfer belt 125 is performed in the overcoating state. The transfer of the black toner image by the photosensitive drum 121 of the black unit 12K is performed in an overcoated state, whereby a color toner image is formed on the surface of the transfer belt 125. The color toner image formed on the surface of the transfer belt 125 is transferred to the paper P conveyed from the paper storage unit 14.

  In addition, a sheet conveyance path 111 extending in the vertical direction is formed at the left position of the image forming unit 12. The sheet conveying path 111 is provided with a pair of conveying rollers 112 at appropriate positions, and the sheet from the sheet storage unit 14 is conveyed toward the transfer belt 125 that is wound around the driving roller 125a by the driving of the conveying roller pair 112. Is done. In the sheet conveyance path 111, a second transfer roller 113 that is in contact with the surface of the transfer belt 125 is provided at a position facing the driving roller 125 a, and the sheet P being conveyed along the sheet conveyance path 111 is separated from the transfer belt 125. The toner image on the transfer belt 125 is transferred onto the paper P by being pressed and sandwiched between the second transfer roller 113.

  The fixing unit 13 performs a fixing process on the toner image on the paper transferred by the image forming unit 12, and includes a fixing roller 131 having an energization heating element serving as a heating source inside, and a fixing roller 131 on the left side. A pressure roller 132 disposed opposite to the fixing roller 131 is provided. Then, the transfer-processed paper P led out from the image forming unit 12 through the paper transport path 111 is heated by the fixing roller 131 while being pressed and clamped between the fixing roller 131 and the pressure roller 132, and the toner is subjected to heat treatment. The image is fixed, and a stable color image is formed on the paper.

  The color-printed paper P that has been subjected to the fixing process is discharged toward the in-body paper discharge tray 151 provided at the top of the apparatus main body 11 through a paper discharge conveyance path 114 extending from the top of the fixing unit 13. Is done.

  The paper storage unit 14 has a paper tray 141 that is detachably mounted at a position below the exposure device 124 in the apparatus main body 11. A sheet bundle is stored in the sheet tray 141. Then, the sheet P is fed out from the sheet bundle stored in the sheet tray 141 one by one by driving the pickup roller 142, and introduced into the image forming unit 12 through the sheet conveyance path 111. In the image forming apparatus 10, the document conveying device 20 according to the present invention is provided at a lower position in the document feeding unit 182 of the automatic document feeder 18.

  Hereinafter, the document conveying device 20 will be described with reference to FIGS. FIG. 2 is a front sectional view showing an embodiment of the document conveying device 20, and FIG. 3 is an enlarged view of a main part thereof. In FIG. 2, the lower guide roller 72 is positioned at the upstream position 72a on the upstream side of the reference position 72b with the left two-point difference line indicating the conveyance roller pair 70, and the lower guide with the two-point difference line on the right side. The state where the roller 72 is positioned at the downstream position 72c downstream of the reference position 72b is shown. FIG. 4 is an explanatory view taken along line IV-IV in FIG. Further, FIG. 5 is a perspective view showing an embodiment of the lower roller unit 80. 2 to 5, the X direction is referred to as the left-right direction and the Y direction is referred to as the front-rear direction. In particular, -X is referred to as the left, + X is the right, -Y is the front, and + Y is the rear.

  First, as shown in FIG. 2, the document conveying device 20 takes the document P0 fed out from the document bundle on the document tray 183 on the image reading position 180c on the automatic reading glass 180b (in FIG. 4, a solid black solid line). And is provided at a position below the document feeder 182 in the automatic document feeder 18.

  The document conveying device 20 includes an upstream conveying roller pair 30 disposed at the upper left of the automatic reading glass 180b, a reading guide 40 provided immediately above the automatic reading glass 180b, and an automatic reading glass 180b. A paper passage 50 formed obliquely from the downstream end (right end) to the downstream side and extending obliquely to the upper right, a pre-guide roller 60 disposed on the upper surface side of the paper passage 50, and the pre-guide roller 60 A plurality of conveying roller pairs 70 arranged in parallel in the document width direction on the downstream side are provided.

  The upstream conveyance roller pair 30, the pre-guide roller 60, and the conveyance roller pair 70 are configured to rotate in synchronization with each other when the driving force of a drive motor (not shown) is transmitted through a gear mechanism (not shown). .

  The upstream-side conveyance roller pair 30 includes an upper conveyance roller 31 and a lower conveyance roller 32 that is disposed so as to face the upper conveyance roller 31 at the lower part so that the circumferential surfaces thereof are in contact with each other. The upper conveyance roller 31 includes an upper conveyance roller shaft 311 provided between a pair of side plate frames provided in the automatic document feeder 18 in a front-rear direction (a direction orthogonal to the paper surface of FIG. 2), and an upper conveyance roller shaft 311. The upper conveying roller body 312 is made of an elastic material such as rubber and is fitted concentrically so as to be integrally rotatable. The lower conveyance roller 32 includes a lower conveyance roller shaft 321 provided between the side plate frames, and a lower conveyance roller made of an elastic material such as rubber that is concentrically and externally fitted to the lower conveyance roller shaft 321. It consists of a roller body 322.

  Then, the document P0 sent from the document tray 183 and reaching the nip portion of the upstream transport roller pair 30 is sent toward the automatic reading glass 180b by the drive rotation of the upstream transport roller pair 30. The original P0 on which the original image has been read while passing through the automatic reading glass 180b passes through the paper path 50 and reaches the conveyance roller pair 70 via the paper path 50. Thereafter, the upper and lower portions of the conveyance roller pair 70 are detected. As the guide rollers 71 and 72 are driven to rotate, they are carried out of the automatic document feeder 18 toward the outside (specifically, the upper surface of the document pressing cover 181).

  The reading guide 40 is for preventing the document P0 reaching the automatic reading glass 180b from being lifted, and is provided in a state of being separated from the upper surface of the automatic reading glass 180b by the thickness dimension of the document P0. . A document passage gap (document reading unit) 41 through which the document P0 can pass is formed between the lower surface of the reading guide 40 and the upper surface of the automatic reading glass 180b.

  Accordingly, the original P0 fed out from the original bundle on the original tray 183 is conveyed toward the original passage gap 41 between the automatic reading glass 180b and the reading guide 40 by the upstream conveying roller pair 30, and is used for automatic reading. After the original image is read at the image reading position 180c (FIG. 4) on the glass 180b, it is sent out toward the paper path 50.

  As shown in FIG. 3, the sheet path 50 includes an upper guide member 51 that is inclined upward and to the right, and a lower guide that is separated from the upper guide member 51 by a predetermined distance at a position below the upper guide member 51. A member 52 and a gap formed between the lower guide member 52 and the upper guide member 51 are provided. Thereafter, the original P0 introduced into the paper path 50 is transported through the paper path 50 by the driving rotation of the pre-guide roller 60 and the transport roller pair 70, and is discharged to a paper discharge tray formed on the upper surface of the document pressing cover 181. It will be discharged towards.

  In the present embodiment, as shown in FIG. 4, a plurality of the pre-guide rollers 60 are arranged in parallel in the document width direction orthogonal to the document transport direction (five in the example shown in FIGS. 4 and 5). ing. Each pre-guide roller 60 includes a pre-guide roller shaft 61 and a synthetic resin pre-guide roller body 62 that is concentrically fitted to the pre-guide roller shaft 61 so as to be integrally rotatable.

  Each of the pre-guide rollers 60 is provided on the upper surface side of the sheet path 50 between the automatic reading glass 180 b and the conveying roller pair 70 by being supported between a pair of brackets provided on the upper guide member 51. It has been.

  Each of the conveying roller pairs 70 includes an upper guide roller 71 and a lower guide roller 72 disposed so as to face the lower surface so that the peripheral surface thereof is in contact with the peripheral surface of the upper guide roller 71.

  The upper guide rollers 71 are arranged in the same number as the pre-guide rollers 60 on the downstream side (right side) of the pre-guide rollers 60, as indicated by the two-dot chain line in FIG. As shown in FIG. 3, the upper guide roller 71 includes an upper guide roller shaft 711 extending in the document width direction orthogonal to the document conveying direction, and a rubber that is externally fitted to the upper guide roller shaft 711 so as to be integrally rotatable. And an upper guide roller main body 712 made of an elastic material.

  The upper guide roller shaft 711 is installed on the side plate frames before and after the housing of the automatic document feeder 18. The plurality of upper guide roller bodies 712 are externally fitted to the upper guide roller shaft 711 at an equal pitch, and lower portions thereof protrude from the upper guide member 51 into the paper path 50.

  The plurality of lower guide rollers 72 are mounted on the lower roller unit 80 so that each of the lower guide rollers 72 can move in the left-right direction and can be set in the left-right direction. Each lower guide roller 72 is made of an elastic material such as a lower guide roller shaft 721 extending in the document width direction orthogonal to the document conveying direction, and a rubber or the like externally fitted to the lower guide roller shaft 721 so as to be integrally rotatable. It consists of a lower guide roller body 722.

  In this embodiment, as shown in FIG. 4, the lower guide roller 72 has a pair of lower guide rollers 72 adjacent to the front and rear of the central one, and a reference position 72 b is set. The central lower guide roller 72 is set at an upstream position 72a that is shifted by a distance d1 slightly upstream (leftward) from the reference position 72b. That is, the lower guide roller 72 at the center in the document conveying direction is provided at a position closer to the pre-guide roller 60 than the other lower guide rollers 72.

  Further, the lower guide rollers 72 provided at the front and rear ends are set at a downstream position 72c that is shifted by a distance d2 slightly toward the downstream side (right side) from the reference position 72b. That is, when the nip portion is taken as a reference, each conveyance roller pair 70 is positioned at the most upstream side in the document conveyance direction, and gradually positioned at the downstream side toward the end in the document width direction. It can be said that

  Even if each lower guide roller 72 is shifted to the upstream side and the downstream side with respect to the reference position 72b, the left and right shifts so that the peripheral surface comes into contact with the corresponding peripheral surface of the upper guide roller 71, respectively. The amount is set. Incidentally, since each upper guide roller 71 is pivotally supported by one upper guide roller shaft 711, it is set at the same position in the left-right direction.

  Hereinafter, the lower roller unit 80 will be described with reference to FIG. As shown in FIG. 5, the lower roller unit 80 includes a base plate 81 that is long in the front-rear direction and a plurality of pairs (five pairs in the example shown in FIG. 5) formed by cutting and raising the left end edge of the base plate 81. A bracket 82, a plurality of roller holders 83 supported by each bracket 72, and a coil spring (biasing member) 84 that applies a biasing force to each roller holder 83 are provided.

  The base plate 81 includes a flat plate main body 811 and a folded edge 812 formed by folding the right edge of the plate main body 811 upward. The base plate 81 is structurally strong by forming the folded edge 812 on the plate body 811.

  Each of the pair of brackets 82 is provided with a cut from the left edge of the plate body 811 toward the right, and the front and rear portions of the cut are cut and raised upward to extend parallel to each other in the left-right direction. It is formed with. A roller holder 83 is mounted between the pair of brackets 82. Each bracket 82 is provided with a long hole 821 extending in the left-right direction for fitting a screw shaft (projecting shaft) 834 described later of the roller holder 83 into the bracket 82.

  The roller holder 83 has a pair of longitudinal side plates 831 extending in the front-rear direction extending in the left-right direction, a top plate 832 erected between the upper edge portions on the right side of the center of the elongated side plate 831, and the elongated side plates 831. A bifurcated piece 833 formed so as to rise to the left from the left edge portion, and a pair of screw shafts 834 projecting from the substantially central portion in the left-right direction of each of the elongated side plates 831 in opposite directions. It has.

  The forked gap size of the forked piece 833 is set slightly smaller than the diameter size of the lower guide roller shaft 721 of the lower guide roller 72. Accordingly, the lower guide roller shaft 721 projecting forward and backward from the lower guide roller body 722 is press-fitted into the fork and the lower guide roller 72 is mounted on the roller holder 83.

  Then, each screw shaft 834 of the roller holder 83 to which the lower guide roller 72 is attached is fitted into each of the long holes 821 of the pair of brackets 82, and a nut (position fixing member) 835 is continuously screwed to each screw shaft 834. The roller holder 83 is attached to the base plate 81 by fastening.

  The coil spring 84 is fitted into a mounting recess 832 a having a lower end recessed in the upper surface of the top plate 832 in a compressed state, and the upper end is stopped against a lower surface of an appropriate place of the lower guide member 52 in a state of being prevented from coming off. As a result, a biasing force directed clockwise around the screw shaft 834 is applied to the roller holder 83. As a result, the peripheral surface of the lower guide roller 72 comes into contact with the peripheral surface of the upper guide roller 71.

  In the example shown in FIG. 5, the roller holder 83 at the center in the front-rear direction has a screw shaft 834 fitted and inserted into the long hole 821 of the bracket 82 and is positioned at the leftmost part in the long hole 821. As a result, the lower guide roller 72 is positioned at the upstream position 72a.

  The front and rear roller holders 83 adjacent to the center roller holder 83 are fastened by a nut 835 with the screw shaft 834 positioned at the center in the left-right direction of the elongated hole 821, thereby A pair of lower guide rollers 72 is set at the reference position 72b.

  Furthermore, the roller holder 83 at each of the front and rear ends is fastened by a nut 835 in a state where the screw shaft 834 is fitted into the rightmost portion of the long hole 821, so that the lower guide rollers 72 at both ends are positioned at the downstream positions. The position is set at 72c.

  Even if the lower guide roller 72 is set in any position in the left-right direction, the roller holder 83 is urged clockwise around the screw shaft 834 by the urging force of the coil spring 84. As a result, the lower guide roller 72 is urged. The peripheral surface of the roller 72 comes into press contact with the peripheral surface of the upper guide roller 71.

  As described above in detail, the document conveying device 20 according to the present embodiment is configured so that the document is placed in the document passage gap 41 between the automatic reading glass 180b in the contact glass 180 and the reading guide 40 disposed to face the automatic reading glass 180b. An image reading unit composed of an automatic reading glass 180b and a reading guide 40 that causes a predetermined image reading device 17 to read a document image by passing P0, and a document after image reading formed on the downstream side of the document reading unit A sheet path 50 through which P0 passes, a pre-guide roller 60 disposed on the upper surface side of the sheet path 50, and a plurality of upper guide rollers arranged in parallel in the document width direction on the downstream side of the pre-guide roller 60 71 and a plurality of conveying roller pairs 70 including a plurality of lower guide rollers 72 arranged in parallel so that the peripheral surface abuts on the peripheral surface of the upper guide roller 71. .

  And the thing of the center part in the some lower guide roller 72 is provided in the position which approached the pre-guide roller 60 compared with the other thing.

  According to the document feeder 20 having such a configuration, the document image P0 sent between the automatic reading glass 180b of the document reading unit and the reading guide 40 is read through the automatic reading glass 180b. Subsequently, after being guided to the pre-guide roller 60 through the paper passage 50, the tip edge portion is a nip portion between the lower guide roller 72 at the central portion and the upper guide roller 71 at the central portion (that is, the conveyance roller pair 70 in the central portion). Reach the nip).

  Thereafter, the original P0 conveyed by the driving rotation of the upper and lower guide rollers 71 and 72 has its leading edge sequentially in the nip portion of the upper and lower guide rollers 71 and 72 other than the central portion (that is, the conveying rollers other than the central portion). The nip portion of the pair 70 is reached, and the conveyance is continued by these driving rotations while being nipped by the upper and lower guide rollers 71 and 72 other than the central portion.

  In this way, the document P0 that has passed over the automatic reading glass 180b is relayed by the pre-guide roller 60 before reaching the central conveying roller pair 70 from the automatic reading glass 180b. The flickering phenomenon at the leading edge of the document P0 that occurs when the pre-guide roller 60 does not exist is suppressed by the pre-guide roller 60. Therefore, when the pre-guide roller 60 is not provided, the state of conveyance of the original P0 on the automatic reading glass 180b is unstable due to the flickering of the leading edge, and proper image reading processing cannot be performed. Generation is effectively suppressed.

  Further, the original P0 from which the original image has been read by the original reading unit is relayed and conveyed by the driving rotation of the pre-guide roller 60, and is first nipped by the conveyance roller pair 70 in the central portion so that the conveyance is continued. As a result, it is possible to effectively prevent the occurrence of inconveniences such as wrinkles on the original P0 and distortion of the read image due to oblique conveyance. it can.

  Then, the original P0 conveyed by a small distance by the conveyance roller pair 70 at the center in a proper posture is immediately conveyed by a plurality of other conveyance roller pairs 70, so that the original P0 is externally maintained in a stable state. Can be discharged.

  Further, the transport roller pair 70 is set at the upstream position 72a at the center in the front-rear direction, and the transport roller pair 70 adjacent to the center roller is positioned at the reference position 72b downstream from the upstream position 72a. Since the end conveyance roller pair 70 is positioned at the downstream position 72c further downstream from the reference position 72b, the document P0 that has passed through the document passage gap 41 passes through the pre-guide roller 60 in the sheet path 50. It reaches the lower guide roller 72 at the center of the plurality of conveyance roller pairs 70.

  Then, the original P0 having the central portion of the leading edge thereof nipped by the central conveyance roller pair 70 is sequentially conveyed toward the conveyance roller pair 70 closer to the end as the conveyance roller pair 70 is driven. Since the nipping is performed, the conveyance force of each conveyance roller pair 70 is always applied to the original P0 equally on the left and right with respect to the center line extending in the conveyance direction. As a result, the original P0 is conveyed in an extremely stable state. Discharged outside.

  Furthermore, in this embodiment, a lower roller unit 80 for supporting the plurality of lower guide rollers 72 is employed.

  The lower roller unit 80 includes a plurality of roller holders 83 that rotatably support the lower guide rollers 72 around the lower guide roller shaft 721, a base plate 81 that supports the plurality of roller holders 83, and a plurality of roller holders 83. Coil springs that urge the roller holder 83 so that a plurality of pairs of brackets 82 arranged in parallel to be mounted on the base plate 81 and a peripheral surface of each lower guide roller 72 abut against a corresponding peripheral surface of each upper guide roller 71. 84.

  The pair of brackets 82 are respectively provided with long holes 821 extending in the front-rear direction facing each other, while the roller holder 83 protrudes in opposite directions from both side surfaces and is long. A screw shaft 834 to be inserted into the hole 821 is provided, and a nut 835 is screwed and fastened to the screw shaft 834 so that the lower guide roller 72 is set and fixed in position.

  According to the lower roller unit 80, the position of the lower guide roller 72 can be easily set via the roller holder 83 by moving the screw shaft 834 forward and backward within the elongated hole 821. Then, the set position of the lower guide roller 72 can be fixed by fastening the screw shaft 834 to the bracket 82 with the nut 835 while the position is set.

  Therefore, compared to the case where the installation position of the lower guide roller 72 is changed from the beginning as in the prior art, the screw shaft 834 can be moved within the elongated hole 821 and easily positioned after the lower guide roller 72 is attached. In addition, fine adjustment of the position of the lower guide roller 72 after attachment is easy, and the workability of the installation work and the position adjustment work of the lower guide roller 72 can be greatly improved.

  Then, with the position of each lower guide roller 72 set, each lower guide roller 72 is brought into close contact with the corresponding peripheral surface of the upper guide roller 71 by the urging force of the coil spring 84. The original P0 that has reached the nip portion between the upper and lower guide rollers 71 and 72 can be reliably conveyed by the driving rotation of the conveying roller pair 70.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, a copying machine has been described as an example of the image forming apparatus 10 to which the document conveying device 20 according to the present invention is applied. However, a facsimile machine may be used instead of the copying machine. .

  (2) In the above-described embodiment, only the lower guide roller 72 at the center is set at the upstream position 72a upstream from the others, and the reference position 72b downstream from the upstream position 72a and the reference position 72b toward the end sequentially. The position is set at the downstream position 72c on the further downstream side, but instead, only the lower guide roller 72 at the center in the front-rear direction is set at the upstream position 72a, and the other lower guide rollers 72 are located at the upstream position 72a. The position may be set at the same left and right position on the downstream side.

  (3) In the above embodiment, the elongated holes 821 are formed in the plurality of pairs of brackets 82 formed in the plate body 811 of the base plate 81, respectively, while the pair of elongated side plates 831 of the roller holder 83 are opposite to each other. A pair of threaded shafts 834 projecting toward each other are projected, and each threaded shaft 834 is fitted and inserted into the corresponding elongated hole 821 and then fastened with a nut 835. Instead of this, the roller holder 83 May be directly fixed to a predetermined frame of the automatic document feeder 18 without using the base plate 81, and the position of each lower guide roller 72 may be set by changing the fixing position.

1 is a front cross-sectional view showing an embodiment of an internal structure of an image forming apparatus to which a document conveying device according to the present invention is applied. FIG. 3 is a front sectional view showing an embodiment of the document conveying device. FIG. 3 is an enlarged view showing a main part of the document conveying device shown in FIG. 2. It is explanatory drawing of the IV-IV line sectional view of FIG. It is a perspective view which shows one Embodiment of a lower roller unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Apparatus main body 111 Paper conveyance path 112 Conveying roller pair 113 Transfer roller 114 Paper discharge conveyance path 12 Image forming part 12M Magenta unit 12C Cyan unit 12Y Yellow unit 12K Black unit 121 Photosensitive drum 122 Developing device 123 Charging Device 124 Exposure Device 125 Transfer Belt 125a Drive Roller 125b Driven Roller 126 Transfer Roller 13 Fixing Unit 131 Fixing Roller 132 Pressure Roller 14 Paper Storage Unit 141 Paper Tray 142 Pickup Roller 15 Paper Output Unit 151 In-Cylinder Paper Output Tray 16 Image Reading unit 17 Image reading device 170 Exterior cover 171 Housing 172 Reading unit 173 Unit 18 Automatic document feeder 180 Contact glass 180a Book original glass 180b For automatic reading Glass 180c Image reading position 181 Document pressing cover 182 Document feeding section 183 Document tray 20 Document transport device 30 Upstream transport roller pair 31 Upper transport roller 311 Upper transport roller shaft 312 Upper transport roller body 32 Lower transport roller body 321 Lower transport roller shaft 322 Lower conveyance roller body 40 Reading guide 41 Original passage gap (original reading section)
50 Paper path 51 Upper guide member 52 Lower guide member 60 Pre-guide roller 61 Pre-guide roller shaft 62 Pre-guide roller body 70 Conveying roller pair 71 Upper guide roller 711 Upper guide roller shaft 712 Upper guide roller body 72 Lower guide roller 721 Lower guide Roller shaft 722 Lower guide roller body 72a Upstream position 72b Reference position 72c Downstream position 80 Lower roller unit 81 Base plate 811 Plate body 812 Folding edge 82 Bracket 821 Long hole 83 Roller holder 831 Elongation side plate 832 Top plate 832a Mounting recess 833 Two-forked piece 834 Screw Shaft (projecting shaft)
835 Nut (position fixing member)
84 Coil spring (biasing member)
P paper P0 manuscript

Claims (4)

An image reading unit for reading an image of a document fed out one by one from a document bundle;
A paper path through which the original after image reading formed on the downstream side in the original conveying direction of the original reading unit passes;
A pre-guide roller disposed on the upper surface side of the paper path;
From a plurality of upper guide rollers and a plurality of lower guide rollers arranged side by side so that the peripheral surfaces of the upper guide rollers are in contact with the peripheral surface of the upper guide rollers. A plurality of conveying roller pairs,
The document conveying apparatus according to claim 1, wherein one of the plurality of lower guide rollers at a central portion in the document width direction is provided at a position closer to the pre-guide roller than the other ones.   2. The document transport according to claim 1, wherein the pair of transport rollers is positioned at the most upstream side in the central portion, and is gradually set at the downstream side toward the end in the document width direction. apparatus. A lower roller unit for supporting the plurality of lower guide rollers is provided,
The lower roller unit includes a plurality of roller holders that rotatably support each lower guide roller about a lower guide roller axis, a base plate that supports the plurality of roller holders, and a plurality of roller holders arranged in parallel to be mounted on the base plate. A plurality of brackets provided, and a biasing member that biases the roller holder so that the peripheral surface of each lower guide roller abuts the corresponding peripheral surface of each upper guide roller, respectively.
The pair of brackets are respectively provided with long holes extending in the front-rear direction facing each other, while the roller holder is provided with projecting shafts projecting in opposite directions from both side surfaces thereof, The document conveying apparatus according to claim 1, further comprising a position fixing member that fixes a position of the projecting shaft in the long hole. An image forming apparatus that performs a predetermined image forming process based on a document image that is conveyed by the document conveying device according to claim 1 and that is read by a document reading unit.

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