JP2005247530A - Paper conveying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for preventing generation of image failure by paper dust or the like by efficiently removing foreign matter such as paper dust deposited on the paper in a paper conveying device provided with an image formation part or an image reading part. <P>SOLUTION: The paper conveying device is provided with a paper feed cassette 105 for successively feeding the paper for recording the image; an image formation part 106 for forming a toner image to an electro-static latent image using a photoreceptor drum 60 and recording the image on the paper; and a conveying passage 108 for conveying the paper from the paper feed cassette 105 to a paper delivery tray 107 through the image formation part 106. The conveying passage 108 reaching from the paper feed cassette 105 to the image formation part 106 is curved so as to slide-contact the recording surface of the conveyed paper with a guide surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet to an image forming unit or an image reading unit in a printer, a facsimile, a copying machine, or the like.

  Printers, facsimiles, copiers, and the like are equipped with an image forming unit for recording characters and images on paper. FIG. 7 shows an example of the image forming unit. The surface of the photoconductive drum 902 is charged by the charging device 901 to which a predetermined bias voltage is applied, and the LED head 903 responds to the image information according to the image information. By selectively exposing the photosensitive drum 902, an electrostatic latent image is formed on the surface of the photosensitive drum 902. The developing device 904 supplies charged toner to the electrostatic latent image to form a toner image, and the toner image is transferred onto a sheet by a transfer device 905 to which a predetermined bias voltage is applied. Thereafter, heat and pressure are applied to the paper by a fixing device 906, and the transferred toner image is fixed. On the other hand, after the surface charge of the photosensitive drum 902 to which the toner has been transferred is removed by the charge removal device 907, the toner remaining on the surface is removed by the cleaning device 908 and is charged again by the charging device 901. (For example, refer to Patent Document 1).

  Some scanners, facsimiles, copiers, and the like are equipped with a paper conveyance device such as an auto document feeder (hereinafter referred to as “ADF”) that sequentially feeds a plurality of documents. According to the transport device, a plurality of documents placed on the document tray can be continuously and automatically transported to the reading position.

  FIG. 8 shows a cross-sectional structure of a conventional ADF, and the ADF conveys the paper on the document tray 911 so as to make a U-turn from above to the paper discharge tray 912 provided below the document tray 911. In the conveyance process, an image reading unit equipped with a CCD or the like reads an image of the paper. Specifically, as shown in the figure, a conveyance path 913 that leads from the document tray 911 to the paper discharge tray 912 is formed, and a paper feed roller 914 and a conveyance path 913 provided near the paper feed port of the conveyance path 913. The paper on the document tray 911 is continuously transported to the paper discharge tray 912 by transport rollers 915 appropriately disposed on the paper. The sheet fed from the document tray 911 to the conveyance path 913 is scanned on the first surface by the first image reading unit 916 in the conveyance process, and further on the second surface by the second image reading unit 917 downstream thereof. Is read (see, for example, Patent Document 2).

JP 2003-307987 A JP-A-8-133551

  In the image forming section as described above, the mainstream is to negatively charge the photosensitive drum 902, but recently, a method of positively charging the photosensitive drum 902 has been devised. For example, in a method of charging the photosensitive drum 902 by corona discharge using a scorotron charger for the charging device 901, it is better to use a positively charged photosensitive member for the photosensitive drum 902 and generate a positive corona discharge in the charging device 901. There is an advantage that less ozone is generated than when negative corona discharge is generated. However, the paper dust adhering to the paper is often negatively charged. When the toner image formed on the photosensitive drum 902 is transferred to the paper, the photosensitive drum is charged positively with the paper dust. Move to 902. The paper dust is removed together with residual toner by the cleaning device 907, but a large amount of foreign matter such as paper dust may adhere to the poor quality paper, and the paper dust that cannot be completely removed by the cleaning device 907 is exposed to light. There is a problem of remaining on the body drum 902 and causing image defects such as fogging and black streaks. Further, when the residual toner is reused as in the so-called cleanerless system, there is a problem that paper dust or the like is mixed into the collected residual toner, and image defects such as white spots occur.

  On the other hand, also in the ADF described above, paper dust adhering to the paper causes image defects. For example, paper dust adhering to the conveyance roller 915 or paper dust falling from the paper and staying in the vicinity of the reading position of the first image reading unit 916, which is the lowest position of the substantially U-shaped conveyance path 913 in the horizontal direction, May be reattached to the sheet conveyed to the second image reading unit 917 and cause image defects such as black stripes.

  The present invention has been made to solve such a problem, and in a paper conveying apparatus provided with an image forming unit or an image reading unit, foreign matters such as paper dust adhering to the paper are efficiently removed to make paper dust etc. An object of the present invention is to provide means for preventing the occurrence of image defects due to the above.

  The present invention relates to a sheet conveying apparatus that sequentially supplies accumulated sheets to a conveying path and discharges them to a sheet discharge tray through an image reading unit for reading an image on the sheet or an image forming unit for recording an image on the sheet. The conveyance path on the upstream side of the image reading section or the image forming section is curved so that the reading surface or recording surface of the sheet being conveyed is brought into sliding contact with the guide surface.

  Further, the present invention provides the sheet conveying apparatus, wherein the image forming unit forms an electrostatic latent image by selectively exposing the photosensitive drum charged by the charging device according to image information, A developing device forms a toner image on the electrostatic latent image, transfers the toner image onto a sheet by a transfer device, and fixes the transferred toner image on the sheet by a fixing device. .

  Further, the present invention provides the paper transport apparatus, wherein the transport path extends upward from the paper supply position to the image forming unit, and a pair of transports for transporting the paper while nipping the transport path. A roller is provided, and a conveyance roller on the recording surface side is provided with a foreign matter collecting mechanism for removing foreign matter adhering to the roller surface, and the recording surface of the sheet being conveyed is placed almost directly above the conveyance roller on the recording surface side. A position for sliding contact with the guide surface is provided.

  In the paper transporting apparatus according to the present invention, the transport path on the upstream side of the image forming unit is substantially S-shaped with the center of curvature disposed on the opposite side on the upper and lower sides of the transport roller. And

  Also, in the present invention, in the paper transport device, the image reading unit includes a first image reading unit that reads a first surface of the paper and a second image reading unit that reads a second surface of the paper, The conveyance path on the upstream side of the second image reading unit and on the downstream side of the first image reading unit is curved so that the second surface of the sheet is in sliding contact with the guide surface. .

  The present invention is also characterized in that, in the paper conveying apparatus, the conveying path is curved in a substantially S shape.

  According to the paper conveyance device of the present invention, the conveyance path on the upstream side of the image reading unit or the image forming unit is curved so that the reading surface or the recording surface of the conveyed paper is in sliding contact with the guide surface. Therefore, paper dust or the like adhering to the paper before reaching the image forming unit or the image reading unit is removed by sliding contact with the guide surface. Thereby, the paper dust adhering to an image forming part or an image reading part can be reduced, and an image defect can be suppressed.

  According to the present invention, the image forming unit forms an electrostatic latent image on the photosensitive drum charged by the charging device according to image information, thereby forming an electrostatic latent image. The developing device forms a toner image on the image, the toner image is transferred onto the paper by the transfer device, and the transferred toner image is fixed on the paper by the fixing device. It is possible to effectively suppress image defects due to the above.

  Further, according to the present invention, the transport path extends upward from the paper feed cassette to the image forming unit, and the pair of transport rollers for transporting the paper while nipping the paper in the transport path. The recording surface side transport roller is provided with a foreign matter collecting mechanism for removing foreign matter adhering to the roller surface, and the recording surface of the paper being transported is a guide surface substantially directly above the recording surface side transport roller. When the transport roller nips the paper, it removes the paper dust by attaching it to the transport roller, and the paper dust removed by the sliding contact with the guide surface is on the recording surface side. Falls on the transport roller and is collected by the foreign matter collecting mechanism. Thereby, paper dust etc. do not remain in a conveyance path or a conveyance roller, and reattachment of paper dust etc. can be prevented.

  According to the present invention, the conveyance path from the paper feed cassette to the image forming unit is substantially S-shaped with the center of curvature arranged on the opposite side on the upper and lower sides of the conveyance roller. While achieving smooth conveyance without giving an excessive burden, the above-described effects can be achieved with a simple configuration.

  Further, according to the present invention, the conveyance path upstream of the second image reading unit and downstream of the first image reading unit is curved so that the second surface of the sheet is brought into sliding contact with the guide surface. For example, it is possible to effectively suppress image defects in the second image reading unit when performing double-sided reading of paper in one pass.

  Further, according to the present invention, since the transport path is curved in a substantially S shape, smooth transport can be achieved without imposing an excessive burden on the paper, and the above effect can be achieved with a simple configuration. be able to.

  FIG. 1 is a schematic perspective view showing the external appearance of a copy / facsimile multifunction peripheral 100 equipped with a paper transport apparatus according to the first embodiment of the present invention. As shown in FIG. Includes a reading table 101 that functions as a flatbed scanner, a document pressing cover 102 that fixes a document on the reading table 101, an operation panel 103 for inputting start of image reading and recording, and a sheet. The image forming unit includes an image forming unit that records an image, a main body 104 that includes a transmission unit that transmits an image, and the like, and a paper feed cassette 105 that sequentially supplies sheets for recording an image. In the copy / facsimile multifunction peripheral 100, the sheet conveying apparatus conveys a sheet from a sheet feeding cassette 105 to an image forming unit in a main body 104, and images, characters, and the like read by the image forming unit by a flat bed scanner or the like. It is realized as being recorded on paper.

  FIG. 2 is a diagram showing an internal configuration of the main body 104 and the paper feed cassette 105 constituting the paper transport device in the copy / facsimile multifunction peripheral 100. As shown in the figure, a paper feed cassette 105 for sequentially supplying paper for recording images is disposed at the bottom of the apparatus, and an image forming unit 106 is disposed above the paper feed cassette 105. A paper discharge tray 107 is disposed above the paper discharge tray 107. A transport path 108 for transporting paper from the paper feed cassette 105 to the paper discharge tray 107 is extended upward from one end side of the paper feed cassette 105 to the image forming unit 106 and further extended upward. After that, it is formed so as to bend in the horizontal direction and lead to the paper discharge tray 107. Although not shown in the drawing, the reading table 101, the document pressing cover 102, and the operation panel 103 are disposed above the paper discharge tray 108. For convenience of explanation, the lower paper feed cassette 105 is omitted in the figure.

  The paper feed cassette 105 has a box shape capable of storing various sizes of paper. The paper feed cassette 105 is provided at the bottom of the apparatus so that it can be drawn out, and can be loaded with paper as needed. Inside the paper feed cassette 105, a guide 50 for holding a paper of a predetermined size at the paper feed position is disposed. The guide 50 is provided so as to be able to swing within a predetermined range around the fulcrum 50a, and its bottom plate is urged upward by an elastic member to hold a plurality of sheets in a stacked state, and at the top thereof. One end of the paper is always positioned at the paper feed position. A paper feed roller 51 and a separation pad 52 are provided at the paper feed position, and the uppermost paper positioned at the paper feed position by the guide 50 is in pressure contact with the paper feed roller 51. The paper feed roller 51 is formed by fixing a roller made of silicon and EPDM (Ethylene-Propylene-Diene Methylene Linkage) on a metal roller shaft, for example, and is the top paper The sheet is fed into the conveyance path 108 by rotating while being pressed against the sheet. The friction coefficient with respect to the separation pad 52 and the paper is lower than the friction coefficient with respect to the paper of the paper feed roller 51 and higher than the friction coefficient between the papers, and can be formed of, for example, urethane resin. Such a separation pad 52 is stuck on the upper surface of the separation pad holder 53. The separation pad holder 53 is disposed below the paper feed roller 51 so as to be movable up and down and is urged upward by an elastic member (not shown). The sheets that are pressed against the roller surface and pass through the pressed portion are separated and supplied one by one by friction.

  The image forming unit 106 includes a scorotron charger (charging device) 61, an LED printer head 62, a developing device (developing device) 63, a transfer device (transfer device) 64, and a cleaning device disposed around the photosensitive drum 60. 65 and a fixing device (fixing device) 66 disposed in the conveyance path 108 on the downstream side of the photosensitive drum 60.

  The photoconductor drum 60 has a photoconductive film formed of an organic photoconductor on the surface and is rotated at a predetermined speed by a motor. The scorotron charger 61 is of a so-called non-contact corona charging method, and although not shown in detail in the drawing, a discharge wire is disposed at the approximate center of a casing electrode forming a half space, and a photosensitive member. A grid electrode is disposed on the drum 60 side, and a predetermined voltage is applied to the discharge wire to generate corona discharge. The amount of ions generated by the corona discharge is controlled by the grid electrode. The photosensitive drum 60 is positively charged by the scorotron charger 61. Of course, negative charging may be used, but the use of positive charging has the advantage that the amount of ozone generated from the scorotron charger 61 is small. In the case of negative charging, other charging devices such as a contact roller charging method may be employed instead of the non-contact corona charging method.

  The LED printer head 62 is a so-called self-luminous printer head in which LED arrays are arranged in parallel for the number of recording pixels, and light emitted from the LED arrays is imaged on the surface of the photosensitive drum 60 by a Selfoc lens array. The surface of the photosensitive drum 60 is selectively exposed to the photosensitive drum 60 based on image information, and an electrostatic latent image is formed on the surface. The surface of the photosensitive drum 60 is positively charged as described above, and the surface potential of the portion exposed by the LED printer head 62 is attenuated, and an electrostatic latent image is formed by the potential difference from the unexposed portion. The As the image information, for example, an image of a document read by the reading table 101 functioning as a flatbed scanner is transmitted to the LED printer head 62 as an electric signal. As the exposure device, in addition to the LED printer head 62, a scanning optical system using a semiconductor laser may be adopted.

  The developing device (developing device) 63 includes a supply roller 67, a development roller 68, and a toner container 69, and a bias voltage applied to the supply roller 67 and the development roller 68 from an electric circuit (not shown). Due to this difference, the toner in the toner container 69 is supplied to the developing roller 68 via the supply roller 67. The toner layer formed on the surface of the developing roller 68 is made uniform by pressing the regulating blade 70 to which a predetermined bias voltage is applied. In this way, the developing roller 68 having a uniform toner layer formed on the surface is rotated at a position close to the photosensitive drum 60, and on the developing roller 68 due to a potential difference from the electrostatic latent image on the photosensitive drum 60. The toner moves to the photosensitive drum 60, and a toner image is formed on the surface of the photosensitive drum 60 based on the electrostatic latent image.

  The transfer device (transfer device) 64 is a transfer roller made of an EPDM foam, is pressed against the photosensitive drum 60 at a position opposite to the conveyance path 108, and is applied with a bias voltage from an electric circuit (not shown). The toner image on the photosensitive drum 60 is transferred to a sheet. In place of the contact type conductive roller type like the transfer unit 64, a non-contact type transfer device such as a corona transfer unit may be used.

  In the cleaning device 65, a cleaning roller made of EPDM foam is pressed against the photosensitive drum 60 after transfer, and a constant voltage is applied from an electric circuit (not shown), so that the cleaning device 65 remains on the surface of the photosensitive drum 60. The toner and paper dust are removed and the electrostatic latent image is erased. As a result, the surface of the photosensitive drum 60 is cleaned and continuous use is possible. As the cleaning device, other contact type methods such as a blade or a non-contact type can be adopted, and a cleaningless type can also be adopted. The photosensitive drum 60, the scorotron charger 61, the LED printer head 62, the developing device 63, and the cleaning device 65 are integrated as a process cartridge and can be attached to and detached from the main body 104 of the copy / facsimile multifunction peripheral 100. In addition, the process cartridge can be replaced as a unit when the toner is replenished.

  The fixing device 66 heats and presses and fixes the sheet on which the toner image is transferred by a heating roller 72 and a pressure roller 73 that are respectively disposed at positions opposed to the conveyance path 108. The surface of the heating roller 72 is maintained at a predetermined temperature by a heater (not shown). A pressure roller 73 is pressed against the heating roller 72 with a predetermined pressure. The sheet on which the toner image has been transferred is nipped between the heating roller 72 and the pressure roller 73 so that the toner on the sheet is melted and fixed. The image forming unit 106 configured as described above records an image of a document read by the reading table 101 on a sheet.

The sheet is transported from the paper feed cassette 105 to the image forming unit 106 along the transport path 108, and the paper on which the image is recorded is transported to the paper discharge tray 107. Hereinafter, image formation from the paper feed cassette 105 is performed. The configuration of the conveyance path 108 leading to the section 106 will be described in detail.
As shown in FIG. 3, the conveyance path 108 extends substantially upward from the paper feed cassette 105 to the image forming unit 106. In the middle of the conveyance path 108, a pair of conveyance rollers 80 that convey the sheet in a nip state, 81 is provided. The transport rollers 80 and 81 rotate when a rotational force from a driving source such as a motor is transmitted to the roller shaft, and the pair of transport rollers 80 and 81 are positioned at opposite positions of the transport path 108. It is arrange | positioned so that it may press-contact with the roller surface of this. As will be described later, the conveyance roller 80 is preferably longer than the maximum sheet width in order to receive the paper dust that has been wiped off at the sliding contact position P1, and a metal roller or a resin roller can be used. However, a metal roller having a low friction coefficient is suitable so that paper dust or the like attached to the paper does not adhere.

  Of the pair of transport rollers 80 and 81, a foreign substance that removes paper dust and the like attached to the roller surface of the transport roller 80 on the recording surface side of the sheet, that is, the photosensitive drum 60 side of the image forming unit 106. A collecting mechanism 82 is provided, which adheres to the recording surface of the paper, and the recording surface is brought into pressure contact with the roller surface of the conveying roller 80, so that the paper surface moved to the roller surface or the sliding contact position P1 on the roller surface. The fallen paper dust is removed.

  As shown in FIGS. 3 and 4, the foreign matter collecting mechanism 82 includes a scraping piece 83 that is in contact with the roller surface of the transport roller 80, a concave groove 84 that is provided in parallel with the scraping piece 83, And a spiral blade 85 provided in the groove 84. The scraping piece 83 and the concave groove 84 are integrally formed on the side of the conveying roller 80, and the scraping piece 83 protrudes in a substantially horizontal direction along the axial direction of the conveying roller 80, and its tip is on the roller surface. It is in the shape of a blade in contact. A concave groove 84 is continuously formed on the base end side of the scraping piece 83, and paper dust or the like adhering to the roller surface of the conveying roller 80 is scraped into the concave groove 84 by the scraping piece 83. It is like that. The bottom portion of the recessed groove 84 is formed in a semicircular shape, and a spiral blade 85 is disposed in the vicinity of the bottom portion so as to be rotatable about an axis 86. The shaft 86 is driven and transmitted from the conveying roller 80 via a pulley 87, and the paper dust scraped into the concave groove 84 is conveyed to one end side of the concave groove 84 by the rotation of the spiral blade 85. It is accommodated in a container 88 provided on one end side of the concave groove 84. Such foreign matter collecting mechanism 82 removes paper dust and the like adhering to the transport roller 80 as needed, so that the paper dust does not re-adhere to the paper transported thereafter.

  On the other hand, as shown in FIG. 3, the conveyance path 108 from the paper feed cassette 105 to the image forming unit 106 is formed in a substantially S shape with the center of curvature arranged on the opposite side on the upper and lower sides of the conveyance rollers 80 and 81. ing. That is, the conveyance path 108 extending obliquely upward from the sheet feeding position of the sheet feeding cassette 105 becomes a substantially vertical direction by curving in an arc shape with the left side as a center of curvature with respect to the traveling direction, and the conveyance rollers 80 and 81. After that, by curving in an arc shape with the right side as the center of curvature with respect to the traveling direction, the image is directed obliquely upward again toward the image forming unit 106. The guide surface outside the curved portion of the conveyance path 108 on the downstream side of the conveyance rollers 80 and 81 is a sliding contact position P1 of the recording surface of the sheet.

  Such a conveyance path 108 is formed by arranging a pair of conveyance guides 87 and 88 at a predetermined interval through which the sheet can pass, and the sheet is conveyed at the curved portion of the conveyance path 108. , 88 and is guided to bend along the curve of the conveying path 108. Accordingly, in the conveyance path 108 on the downstream side of the conveyance rollers 80 and 81, the conveyed sheet abuts on the conveyance guide 87 outside the curved portion and bends from the substantially vertical direction to the right in the traveling direction, and is conveyed at the sliding contact position P1. The recording surface is conveyed in such a manner that the recording surface contacts the guide surface 87. As a result, paper dust or the like adhering to the recording surface of the paper is removed. Although not shown in the drawing, a rib may be provided on the guide surface of the conveyance guide 87 as appropriate, and a conductive brush is provided in the paper width direction to wipe off paper dust on the recording surface and to make sliding contact with the guide surface. You may make it remove the electrical charge of the paper by. Further, the conveyance guides 87 and 88 constituting the conveyance path 108 may be constituted by a plate-shaped member made of resin or the like, or may be used in combination with the main body 104 or the housing of the process cartridge.

  The slidable contact position P1 is located almost immediately above the conveyance roller 80 on the recording surface side, and the paper dust and the like that have been wiped off at the slidable contact position P1 are located on the conveyance roller 80 along the guide surface of the conveyance guide 87. Fall into. The paper dust and the like are collected by the foreign matter collecting mechanism 82 as described above with the rotation of the transport roller 80. In this way, the recording surface of the paper being conveyed at the sliding contact position P1 downstream of the conveying rollers 80 and 81 is brought into sliding contact with the guide surface, so that paper dust remaining on the recording surface is removed. Even paper with a large amount of foreign matter such as paper dust can be removed before reaching the image forming unit 106, reducing paper dust or the like adhering to the photosensitive drum 60 of the image forming unit 106. Image defects can be prevented from occurring. Further, since paper dust and the like removed by sliding contact with the guide surface falls on the recording surface side conveyance roller 80 and is collected by the foreign matter collection mechanism 82, paper dust and the like are collected on the conveyance path 108 and the conveyance roller 80. It does not remain, and it is possible to prevent paper dust from adhering again to the paper transported thereafter. In addition, by forming the conveyance path 108 from the paper feed cassette 105 to the image forming unit 106 to be substantially S-shaped, smooth conveyance can be achieved without imposing an excessive burden on the paper, and the above-described effects can be achieved with a simple configuration. Can be realized.

Hereinafter, a paper conveying apparatus according to a second embodiment of the present invention will be described.
In the copy / facsimile multifunction peripheral 100, the paper transport device is realized as an ADF 1 on a document pressing cover 102 for fixing the paper on the reading table 101. With the ADF 1, the paper on the document tray 2 is transferred to the document tray. 2 is conveyed so as to make a U-turn from the upper side to the lower side to a paper discharge tray 4 provided below 2, and image reading is performed in the conveyance process.

  As shown in FIG. 5, a platen glass 11 is disposed on the top surface of a substantially rectangular parallelepiped housing 10 in the reading mounting table 101, and a CCD reading unit (first reading unit) is provided in the housing 10. 12 is built-in. As shown in the figure, the CCD reading unit 12 converges the reflected light R, a light source 14 for irradiating light to the reading position X1, a reflection mirror 15 for guiding reflected light R from the document in a predetermined direction, and the like. This is a reading unit of a so-called reduction optical system that includes a condenser lens 16 and a CCD image sensor 17 that converts the convergent light into an electrical signal and outputs it. The CCD reading unit 12 configured as described above moves horizontally with respect to the platen glass 11 when it functions as an FBS, scans the paper on the platen glass 11, and reads when the ADF 1 is used. The image of the paper transported to the position X1 and transported through the transport path 3 is scanned, and the reflected light R from each paper is guided to the CCD 17 to form an image. Although not shown in the drawing, the image signal read by the CCD reading unit 12 and converted into an electric signal is subjected to analog / digital conversion, shading processing, and the like, and is then applied to a sheet by the image forming unit 106. It is recorded or transmitted by a transmission unit such as CODEC.

  The ADF 1 includes a document tray 2 and a paper discharge tray 4 arranged in two upper and lower stages, a conveyance path 3 formed in a lateral U-shape from the document tray 2 to the paper discharge tray 4, and a paper feed port of the conveyance path 3. A paper feed roller 5 and a separation pad 6 which are disposed in the vicinity and sandwich the paper fed from the document tray 2 in the thickness direction and separated, and a transport path 3 are appropriately disposed, and the paper is nipped and transported. The CCD reading unit 12 that is disposed outside the conveyance path 7 immediately downstream of the folding section of the conveyance path and reads the first surface of the conveyed paper, and downstream of the CCD reading unit 12. And a CIS reading unit (second reading unit) 8 that reads the second surface of the sheet being conveyed at the reading position X2 and the vicinity of the discharge port of the conveyance path 3. , Nip the paper after reading, paper discharge tray 4 A discharge roller 9 that discharges become comprises a. The sheet fed from the document tray 2 to the transport path 3 by the ADF 1 is reversed so as to make a U-turn from the top to the bottom along the lateral U-shaped transport path 3, and reaches the reading position X1. When passing through the reading position X1, the CCD reading unit 12 reads an image on the first surface of the document, and further conveyed through the conveyance path 3 to the reading position X2. When passing through the reading position X2, the CIS reading is performed. After the image on the second side of the paper is read by the unit 8, the image is discharged to the paper discharge tray 4 below the document tray 2, so that both sides of the paper can be read in one pass, so-called one pass. .

  The conveyance path 3 is formed in a horizontal U shape so as to connect the document tray 2 and the paper discharge tray 4 arranged in two upper and lower stages, and a platen glass 18 that becomes the reading position X1 immediately downstream of the folded portion. The paper passes above, passes through a reading position X2 downstream of the reading position X1, and communicates with the paper discharge tray 4. Although not shown in detail in the drawing, the conveyance path 3 has an inner guide surface and an outer guide surface constituted by a paper guide disposed in the document pressing cover 102, a housing of the document pressing cover 102, and the like. A thick original can pass through.

  The transport roller 7 is formed by fixing a plurality of roller bodies to a roller shaft at predetermined intervals in the axial direction. For example, a roller made of silicon or EPDM is fixed to a metal roller shaft. The number and position of the roller bodies are appropriately set in consideration of the size of the document to be conveyed. In the present embodiment, four transport rollers are provided inside the transport path 3, and the driven rollers 74 outside the transport path 3 are in pressure contact with the transport rollers 7 with respect to the transport rollers 7. The paper is transported along the transport path 3 while the original is nipped by the transport roller 7 and the driven roller 74.

  The CIS reading unit 8 uses a so-called contact type image sensor, and although not shown in detail in the figure, the reflected light from the original irradiated by the light source is converged on the photoconductive element by a converging fiber. This is a fixed reading means for reading. The CIS reading unit 8 is disposed inside the conveyance path 3 on the downstream side of the CCD reading unit 12. Further, since the CIS adopted in the CIS reading unit 8 has a shallow subject depth, a platen roller 89 is disposed on the outer side of the conveyance path, which is a position opposite to the conveyance path 3, and is conveyed by the platen roller 89. The original is pressed against the reading surface of the CIS reading unit 8 to read the image.

  Here, the conveyance path 3 from the reading position X1 to the reading position X2 is formed in a substantially S-shape as shown in FIGS. That is, the conveyance path 3 extends obliquely upward from the reading position X1 while curving in an arc shape with the left side as the center of curvature with respect to the paper traveling direction, and then curved in an arc shape with the right side as the center of curvature relative to the traveling direction. By doing so, it becomes substantially horizontal and moves toward the reading position X2. The guide surface inside the portion that curves in the horizontal direction is the sliding contact position P2 of the second surface of the sheet.

  In such a conveyance path 3, the sheet is guided to bend along the curve of the conveyance path 3, and the sheet that has passed through the reading position X <b> 1 contacts the outer guide surface and is conveyed obliquely upward while being bent to the left in the traveling direction. Then, it abuts on the inner guide surface and bends to the right in the traveling direction, and is conveyed in the horizontal direction so as to slide while the second surface is in contact with the inner guide surface at the sliding contact position P2. As a result, paper dust or the like adhering to the second surface of the paper is removed. Although not shown in the drawing, ribs may be provided on the guide surface as appropriate, and a conductive brush is provided in the paper width direction to remove paper dust on the recording surface and to make sliding contact with the guide surface. The charging of the paper may be removed.

  Further, the paper dust or the like that has been wiped off at the sliding contact position P2 falls on the outer guide surface of the conveyance path 3 and falls toward the reading position X1 according to the inclination, and the roller of the driven roller 74 facing the conveyance roller 7. As shown in the figure, by providing the driven roller 74 with a foreign matter collecting mechanism 30 similar to the foreign matter collecting mechanism 82, the paper dust and the like can be collected. Instead of the foreign matter collecting mechanism 30, a concave groove is formed in the outer guide surface upstream of the sliding contact position P2 across the width direction of the transport path 3 so as to receive and store the falling paper dust or the like. May be. As described above, since the second surface of the paper conveyed at the sliding contact position P2 is brought into sliding contact with the guide surface so as to wipe out paper dust and the like, a large amount of foreign matters such as paper dust adhere to the paper. Even if the paper dust adhering to the conveyance roller 7 or the paper dust stored at the reading position X1 reattaches to the paper, the foreign matter can be removed before reaching the CIS reading unit 8, and the CIS reading It is possible to prevent image defects in the unit 8. Further, since paper dust and the like removed by sliding contact with the guide surface is collected by the foreign matter collecting mechanism 30, paper dust or the like remains on the transport roller 7, the driven roller 74, the reading position X1, and the like of the transport path 3. It is possible to prevent the paper dust from re-adhering to the paper transported thereafter. Further, by making the conveyance path 3 from the reading position X1 to the reading position X2 substantially S-shaped, smooth conveyance can be achieved without imposing an excessive burden on the paper, and the above-described effects can be realized with a simple configuration. be able to.

  Note that the configuration of the copy / facsimile multifunction peripheral 100 shown in the present embodiment is merely an example, and the number of transport rollers 7 and 80 may be appropriately increased according to the distance of the transport paths 3 and 108, the image forming unit 106, Needless to say, the design of the ADF 1 can be changed as appropriate without departing from the scope of the present invention, such as changing the configuration of the ADF 1 to another known configuration.

1 is a schematic perspective view showing an external configuration of a copy / facsimile multifunction peripheral 100 according to a first embodiment of the present invention. 2 is a schematic diagram showing a configuration inside a main body 104 of the copy / facsimile multifunction peripheral 100. FIG. FIG. 4 is an enlarged view showing a configuration in the vicinity of a conveyance path 108 from a paper feed cassette 105 to an image forming unit 106. 4 is a schematic perspective view showing a configuration of a foreign matter recovery mechanism 82. FIG. It is sectional drawing which shows the internal structure of ADF1 which concerns on the 2nd Embodiment of this invention. FIG. 4 is an enlarged view showing a configuration in the vicinity of a conveyance path 3 from a reading position X1 to a reading position X2. It is a schematic diagram which shows an example of an image formation part. It is a schematic diagram which shows an example of the conventional ADF.

Explanation of symbols

1 ADF (paper transport device)
2 Document tray 3 Transport path 4 Paper discharge tray 8 CIS reading unit (second reading unit)
12 CCD reading unit (first reading unit)
60 Photosensitive drum 61 Scorotron charger (charging device)
63 Developer (Development device)
64 Transfer device (transfer device)
66 Fixing device (fixing device)
80, 81 Transport roller 82 Foreign matter recovery mechanism 105 Paper feed cassette 106 Image forming unit 107 Paper discharge tray 108 Transport path

Claims (6)

  In the paper transport device that sequentially feeds the accumulated paper to the transport path and discharges it to a paper discharge tray through an image reading unit for reading an image on the paper or an image forming unit for recording an image on the paper, the image reading The sheet conveying apparatus is characterized in that the conveyance path on the upstream side of the image forming section or the image forming section is curved so that the reading surface or recording surface of the sheet being conveyed is brought into sliding contact with the guide surface.   The image forming unit forms an electrostatic latent image on the photosensitive drum charged by the charging device according to image information to form an electrostatic latent image, and the developing device applies toner to the electrostatic latent image. 2. The paper conveying apparatus according to claim 1, wherein an image is formed, the toner image is transferred onto a paper by a transfer device, and the transferred toner image is fixed on the paper by a fixing device.   The conveyance path extends upward from the paper supply position to the image forming unit, and a pair of conveyance rollers for nipping and conveying the sheet is provided on the conveyance path, and the conveyance roller on the recording surface side In addition, a foreign matter collecting mechanism for removing foreign matter adhering to the roller surface is provided, and a position where the recording surface of the paper being conveyed is in sliding contact with the guide surface is provided almost directly above the conveying roller on the recording surface side. 3. A paper conveying apparatus according to claim 1, wherein   4. The sheet conveying apparatus according to claim 3, wherein the conveying path on the upstream side of the image forming unit is substantially S-shaped with the center of curvature arranged on the opposite side on the upper and lower sides of the conveying roller.   The image reading unit includes a first image reading unit that reads a first side of a sheet and a second image reading unit that reads a second side of the sheet, and is upstream of the second image reading unit and 2. The sheet conveying apparatus according to claim 1, wherein the conveying path on the downstream side of the first image reading section is curved so that the second surface of the sheet is brought into sliding contact with the guide surface.   6. The sheet conveying apparatus according to claim 5, wherein the conveying path is curved in a substantially S shape.

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