JP5812347B2 - Paper feeding device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a sheet feeding device that pulls out and conveys a sheet from a sheet bundle loaded on a sheet loading table, and an image forming apparatus including the sheet feeding device.

  This type of paper feeding device includes a paper stacking table on which a stack of sheets is stacked, a paper transporting belt disposed above the paper stacking base, and a fan that sucks air through the vent holes of the paper transporting belt. In some cases, the uppermost sheet of the sheet bundle is attracted to and conveyed by the sheet conveying belt by suction of air through the ventilation holes of the conveying belt.

  Also, in such a paper feeding device, air is blown onto the end face of the sheet bundle, air is blown in between the sheets, the sheets are dispersed, and the sheets are sucked one by one from the sheet bundle. This makes it easy to pull out and prevent double feeding of paper.

  For example, in Patent Document 1, air is blown out from the outlet of the leading end abutting portion against which the leading end surface of the sheet bundle is abutted, and this air is blown onto the upper layer of the leading end surface of the sheet bundle to vary each sheet, The uppermost sheet of the sheet bundle is sucked and conveyed by the sheet conveying belt.

JP 2010-247970 A

  By the way, in order to attract the uppermost sheet of the sheet bundle by the sheet conveyance belt, it is necessary to bring the uppermost sheet of the sheet bundle closer to the sheet conveyance belt, and each sheet is blown out by blowing air to the upper layer of the sheet bundle. In order to disperse the air, it is necessary to arrange the air outlet near the upper layer of the sheet bundle. Accordingly, the air outlet is brought close to the paper transport belt.

  However, when the air outlet is brought close to the paper transport belt, the path of the paper transported by being attracted to the paper transport belt becomes narrow.

  For example, in Patent Document 1, since the air outlet of the leading end abutting portion is brought close to the paper conveying belt, the upper surface of the leading end abutting portion approaches the paper conveying belt, and the upper surface of the leading end abutting portion The opening between the sheet conveying belt is narrow, and the sheet that is sucked and conveyed by the sheet conveying belt passes through the narrow opening.

  On the other hand, even if the sheet is adsorbed by the sheet conveying belt, both ends of the sheet are likely to hang down. This is because air leakage is likely to occur between the paper transport belt and both ends of the paper. Alternatively, this is because the width of the suction area by the paper transport belt is adjusted to the medium or small size paper width. This is because, when the width of the suction area by the paper transport belt is matched to the large paper width, when the medium or small size paper is sucked by the paper transport belt, The air hole of the paper transport belt is opened, and a large amount of air is sucked from the open air hole, and the suction force of the medium or small size paper by the paper transport belt is reduced, resulting in poor suction. Because.

  Then, both end portions of the paper hanging down like this are caught in the narrow opening described above, and a jam may occur.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and includes a paper feeding device that does not cause jamming even when both ends of the paper hang down without being attracted by the paper conveyance belt, and the paper feeding device including the same. Another object of the present invention is to provide an image forming apparatus.

In order to solve the above-described problems, the present invention provides a sheet feeding device according to the following first to third aspects.
(1) Paper Feeding Device According to the First Aspect The paper feeding device according to the first aspect of the present invention stacks a sheet bundle on a sheet stacking table, sucks air through a vent hole of a sheet conveying member, A paper feeding device that attracts and conveys a sheet to the sheet conveying member, and is conveyed by the sheet conveying member between the sheet conveying member and a guide portion disposed below the sheet conveying member. The guide portion has a central portion extending in a direction perpendicular to the paper transport direction and each side portion on both sides of the central portion, and the opening portion The side portions of the paper transport member are made lower than the central portion , the air holes of the paper transport member are overlapped with the plurality of suction ports of the suction duct, and air is passed through the air holes of the paper transport member. And sucking into the suction duct through each suction port Wherein each side of the guide portion is provided in the region from the most than the outer end portions of the outer suction port inner part of the suction port to the opposite ends of the guide portion.
Here, since both ends of the paper hang down in the region from the inner side of the outermost ends of the outermost suction ports to both ends of the guide portion, each side portion of the guide portion is provided in such a region. ing.
(2) Paper feeder of the second aspect
A sheet feeding device according to a second aspect of the present invention is configured to stack a sheet bundle on a sheet stacking table, suck air through a vent hole of a sheet conveying member, and adsorb the sheets of the sheet bundle to the sheet conveying member. In the paper feeding device for transporting, an opening through which the paper transported by the paper transport member passes is formed between the paper transport member and a guide portion disposed below the paper transport member. The guide portion has a central portion extending in a direction perpendicular to the paper transport direction and each side portion on both sides of the central portion, and each side on the paper entrance side of the opening portion. A curved track portion that is lower than the central portion and is smoothly curved in a direction perpendicular to the paper transport direction, guides the paper transport member, and curves the paper transport member; The side portions of the curved portion are the outermost portions of the curved track portion. Than the curved top of the two outer are provided from the inside of the site in the region of one end to the other end of the guide portion.
When the paper transport member is curved, the paper adsorbed on the paper transport member is also curved. Then, both end portions of the sheet hang down from the inner portion of the curved outermost portion of the curved track portion. For this reason, each side part of a guide part is provided in the area | region from the inner side part to the both ends of a guide part from the outermost curve top part of the curved track part.
(3) Paper feeder of the third aspect
A sheet feeding device according to a third aspect of the present invention is configured to stack a sheet bundle on a sheet stacking table, suck air through a vent hole of a sheet conveying member, and adsorb the sheets of the sheet bundle to the sheet conveying member. In the paper feeding device for transporting, an opening through which the paper transported by the paper transport member passes is formed between the paper transport member and a guide portion disposed below the paper transport member. The guide portion has a central portion extending in a direction perpendicular to the paper transport direction and each side portion on both sides of the central portion, and each side on the paper entrance side of the opening portion. A lower portion than the central portion, and a plurality of outlets for blowing air in the direction of the sheet bundle are provided to be distributed directly below the central portion of the guide portion and directly below the side portions, The outlet provided in each side portion is The plurality of outlets are located in a position lower than the outlets provided in the section, and the plurality of outlets use the air sucked through the vents of the paper transport member in the direction of the sheet bundle and the air from the vents It is configured to blow out.
By blowing air from the outlet to the upper layer of the sheet bundle, each sheet in the upper layer of the sheet bundle can be dispersed, and only the uppermost sheet of the sheet bundle can be sucked and conveyed by the sheet conveying member. . Since it is preferable to provide the air outlet near the uppermost layer of the sheet bundle, the air outlet is provided at a lower position in the central portion higher than each side portion.

  In the present invention, each side portion is set lower than the central portion on the paper entrance side of the opening. For this reason, even if both ends of the sheet being sucked and conveyed by the sheet conveying member hang down, both ends of the sheet can enter the opening without being caught on the sheet entrance side of the opening. Will not occur.

  For example, in the sheet feeding device of the present invention, the upper surface of each side portion of the guide portion is inclined so as to become lower as the distance from the center portion increases.

  In the paper feeder of the present invention, when the upper surface of each side portion of the guide portion is inclined so as to become lower as the distance from the center portion reaches a certain height, the upper surface reaches the certain height. The constant height is maintained from the part to both ends of the guide part.

  Since the recording paper is rigid, even if both ends of the recording paper hang down, it does not droop drastically. For this reason, even if the upper surface of each side part is not made lower than a certain height, the recording sheet passes through the opening without being caught by each side part.

  Furthermore, in the paper feeding device of the present invention, the upper surface of each side portion of the guide portion is inclined so as to become higher as the opening portion is separated from the paper inlet side.

  In this case, even if both ends of the recording paper hang down, both ends of the recording paper enter the opening without being caught on each side on the entrance side of the opening, and both ends of the recording paper are The sheet is received by the inclined upper surface and is gradually lifted, and the entire sheet is sucked and flattened by the sheet conveying member, and the recording sheet is conveyed.

  For example, in the sheet feeding device of the present invention, a step is provided between each side portion and the central portion of the guide portion so that each side portion is lower than the central portion.

  On the other hand, an image forming apparatus of the present invention includes the paper feeding device of the present invention.

  Such an image forming apparatus of the present invention also has the same operational effects as the sheet feeding apparatus of the present invention.

  As described above, in the present invention, each side portion is set lower than the central portion on the paper entrance side of the opening. For this reason, even if both ends of the sheet being sucked and conveyed by the sheet conveying member hang down, both ends of the sheet can enter the opening without being caught on the sheet entrance side of the opening. Will not occur.

1 is a cross-sectional view illustrating an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. It is a top view which shows the paper feeder of this embodiment. It is a front view which shows a paper feeder. FIG. 3 is a perspective view showing the sheet feeding device with the sheet drawer portion removed, as viewed obliquely from the rear. FIG. 6 is a perspective view showing a paper drawer portion when viewed obliquely from the upper front. It is a perspective view which shows a paper drawer part seeing from diagonally upper back. It is a perspective view which shows a paper drawer part seeing from diagonally lower back. FIG. 4 is a perspective view showing the air intake duct and each paper transport belt of the paper supply device, broken away in a direction orthogonal to the recording paper drawing direction. FIG. 6 is a cross-sectional view illustrating a state of two recording sheets adsorbed by each sheet conveying belt. It is sectional drawing which shows a paper feeding apparatus roughly. FIG. 6 is a cross-sectional view illustrating a state of a recording sheet adsorbed by each sheet conveying belt. FIG. 5 is a rear view showing each sheet conveying belt and a guide unit as viewed from the rear. It is a perspective view which expands and shows the guide part of FIG. 12 seeing from back. It is a rear view which shows the modification of a guide part seeing from back. It is a rear view which shows another modification of a guide part seeing from back. It is a rear view which shows another modification of a guide part seeing from back. (A), (b) is sectional drawing and the bottom view which show the modification of an intake duct.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. The image forming apparatus 1 is roughly composed of a document reading device 2, a printing unit 11, a paper transport unit 12, a paper supply unit 13, and a large-capacity paper feed cassette (LCC) 14.

  In the printing unit 11, after the residual toner on the surface of the photosensitive drum 21 is removed and collected by the cleaning device 26, the surface of the photosensitive drum 21 is uniformly charged to a predetermined potential by the charging device 22, and then the laser exposure device 23. The surface of the photosensitive drum 21 is exposed to form an electrostatic latent image on the surface, and the developing device 24 develops the electrostatic latent image on the surface of the photosensitive drum 21 to form a toner image on the surface of the photosensitive drum 21. To do.

  The transfer roller 25 is pressed against the photosensitive drum 21 to form a nip area with the photosensitive drum 21, and the recording paper conveyed through the paper conveyance path 33 is sandwiched and conveyed in the nip area. At the same time, the toner image on the surface of the photosensitive drum 21 is transferred onto the recording paper. Then, the recording paper is sandwiched between the heating roller 28 and the pressure roller 29 of the fixing device 27 and heated and pressed to fix the toner image on the recording paper.

  On the other hand, the paper supply unit 13 includes a plurality of paper supply cassettes 38. Each paper feed cassette 38 includes a pickup roller 39 and the like for pulling out and feeding out recording sheets one by one, and sends out the pulled-out recording sheets to the sheet transport path 33 of the sheet transport section 12.

  The large-capacity paper feed cassette (LCC) 14 can store a large amount of recording paper, pulls out the recording paper one by one, and sends it out to the paper transport path 33 of the paper transport section 12.

  The recording sheet is conveyed through a sheet conveying path 33 and is discharged to a sheet discharge tray 37 via a transfer roller 25 and a fixing device 27 and a sheet discharge roller 36. In this paper conveyance path 33, the recording paper is temporarily stopped and the leading edges of the recording paper are aligned, and then the recording paper is fed in accordance with the transfer timing of the toner image in the nip area between the photosensitive drum 21 and the transfer roller 25. A registration roller 32 for starting conveyance, a conveyance roller 31 for urging conveyance of a recording sheet, a sheet discharge roller 36, and the like are arranged.

  Further, when printing not only on the front side of the recording paper but also on the back side, the position of the branch claw 35 is switched, and the recording paper is conveyed in the reverse direction from the paper discharge roller 36 to the reverse path 34, so that the recording paper The front and back sides are reversed, and the recording paper is again guided to the registration roller 32, and an image is recorded and fixed on the back surface of the recording paper in the same manner as the front surface of the recording paper, and the recording paper is discharged to the paper discharge tray 37.

  Next, the document reading device 2 mounted on the upper body of the image forming apparatus 1 will be described. In the document reading apparatus 2, the document conveying unit 42 is pivotally supported on the inner side of the first reading unit 41 by a hinge (not shown), and the document conveying unit 42 is moved up and down to move the front portion up and down. 42 can be opened and a document sheet can be placed on the platen glass 44 of the first reading unit 41.

  In the first reading unit 41, the first scanning unit 45 illuminates the original paper surface on the platen glass 44 with the light source 51 while moving in the sub-scanning direction, and reflects the reflected light by the first reflecting mirror 52. Guide to the second scanning unit 46. The second scanning unit 46 reflects the reflected light from the original paper by the second and third reflecting mirrors 53 and 54 while moving following the first scanning unit 45. The reflected light is condensed on a CCD 48 (Charge Coupled Device) by the imaging lens 47, and the image of the original paper is read by the CCD 48.

  When reading the image on the surface of the original sheet conveyed by the original conveying section 42, the first scanning unit 45 is moved to a reading position below the original reading glass 55 as shown in FIG. The second scanning unit 46 is positioned according to the position. In this state, the original paper on the original tray 57 is pulled out by the pickup roller 56, the original paper is conveyed through the original conveyance path 58, and the surface of the original paper is passed through the original reading glass 55 by the light source 51 of the first scanning unit 45. Illuminated, the reflected light from the original paper is guided to the imaging lens 47 by the respective reflection mirrors of the first and second scanning units 45 and 46, the image of the original paper is read by the CCD 48, and the original paper is discharged to the original paper discharge roller 61. To the document discharge tray 62.

  A second reading unit 43 (Contact Image Sensor (CIS)) built in the document conveying unit 42 passes under the second reading unit (CIS) 43 and moves to the document discharge tray 62. The back side of the discharged original paper is illuminated, the reflected light from the back side of the original paper is received, and the image on the back side of the original paper is read.

  The original paper image read by the CCD 48 and the CIS 43 in this way is input to the laser exposure device 23 of the image forming apparatus 1, and the image is recorded on the recording paper in the image forming apparatus 1, and this recording paper is output as a copy original. Is done.

  Next, the configuration of the paper feeding device 71 of the present embodiment built in the large capacity paper feeding cassette 14 will be described in detail. The paper feeding device 71 stacks and stores a large amount of recording paper, pulls out the recording paper one by one, and sends it out to the conveyance path 33 (shown in FIG. 1).

  2 and 3 are a plan view and a front view showing the sheet feeding device 71 of the present embodiment. As shown in FIGS. 2 and 3, the sheet feeding device 71 is disposed on the outer frame 72, the bottom plate 73, the sheet stacking plate 74 disposed on the inner side of the outer frame 72, and one end upper side of the outer frame 72. A paper drawer 75 and the like are provided.

  The sheet stacking table 74 is used for stacking a large amount of recording sheets (sheet bundle) and is provided inside the outer frame 72 so as to be moved up and down. The paper stacking base 74 is formed with an opening 74 a that is long in the recording paper drawing direction (paper transport direction) E. The paper trailing edge guide 76 is supported on the bottom plate 73 so as to be reciprocally movable along the recording paper drawing direction E, and protrudes upward through the opening 74 a of the paper stacking table 74. The recording paper drawing direction (paper conveyance direction) E is the front, and the direction opposite to the drawing direction E is the rear.

  Recesses 74b are formed on both sides of the sheet stacking table 74, and assist ducts 77 and 78 are disposed in the respective recesses 74b. The assist ducts 77 and 78 are supported on both sides of the outer frame 72 so as to be able to reciprocate in a direction perpendicular to the pull-out direction E, and are moved in conjunction with each other or separated from each other. Are moved in conjunction with each other.

  The paper drawing section 75 includes four endless paper conveyance belts 81, a set of rollers 82 and 83 that bridge the paper conveyance belts 81, an intake / exhaust fan 84, an intake duct 85, an exhaust duct 86, and the like. Yes. Each paper transport belt 81 has a large number of air holes 81 a, and air is sucked from the air holes 81 a of each paper transport belt 81 into the intake / exhaust fan 84 through the intake duct 85. Further, the air exhausted from the intake / exhaust fan 84 is guided through the exhaust duct 86 and is blown out from the exhaust duct 86 to the inside of the outer frame body 72 in the direction opposite to the extraction direction E (rearward).

  FIG. 4 is a perspective view showing the outer frame body 72, the bottom plate 73, the paper stacking board 74, and the like as viewed obliquely from the rear side with the paper drawing portion 75 removed. Here, when the sheet bundle is mounted on the sheet stacking board 74, the sheet rear end guide 76 is moved rearward to widen the gap between the sheet rear end guide 76 and the contact plate 72b of the outer frame 72, or The assist ducts 77 and 78 are moved in directions away from each other so that the space between the assist ducts 77 and 78 is wide open. In this state, the sheet bundle is placed on the sheet stacking table 74, and then the sheet trailing edge guide 76 is moved in the drawing direction E, and the trailing edge of the sheet bundle is pushed in the drawing direction E by the column portion 76a of the sheet trailing edge guide 76. Then, the sheet bundle is slid and moved on the sheet stacking table 74, the leading end of the sheet bundle is brought into contact with the contact plate 72 b of the outer frame body 72, and the leading end and the trailing end of the sheet bundle are aligned with the pillars of the sheet trailing end guide 76. Positioning is performed by being sandwiched between the portion 76a and the contact plate 72b of the outer frame 72. Further, the assist ducts 77 and 78 are moved in a direction approaching each other so that both ends of the sheet bundle are sandwiched between the assist ducts 77 and 78 and positioned.

  Further, as shown in FIG. 4, two protruding pieces 74 c are formed on both sides of the paper stacking base 74, and each protruding piece 74 c protrudes from the opening 72 a on both sides of the outer frame 72. On one side of the outer frame 72, two wires 91 are connected to the protruding pieces 74 c on one side of the paper stacking table 74, and each wire 91 is drawn around a plurality of driven pulleys 92 and is wound around a take-up pulley 93. It is connected. Also, on the other side of the outer frame 72, the other two wires 91 are connected to the protruding pieces 74c on the other side of the sheet stacking table 74, and the other wires 91 are connected to a plurality of other driven pulleys 92. It is drawn around and connected to another take-up pulley 93. Each winding pulley 93 is fixed to both ends of a common shaft 94 that is rotatably supported. The shaft 94 is rotationally driven by a pulse motor 95 to rotate each winding pulley 93, and each wire 91 is wound to each winding 91. It is wound around the pulley 93 or is fed out from each winding pulley 93.

  When the shaft 94 is driven to rotate by the pulse motor 95 and each take-up pulley 93 is rotated in the clockwise direction, each wire 91 is taken up by each take-up pulley 93, and the sheet stacking table 74 is raised, and each take-up pulley 93 is moved up. When the take-up pulley 93 is rotated in the counterclockwise direction, each wire 91 is fed out from each take-up pulley 93 and the sheet stacking table 74 is lowered. Further, the rotation angle of the take-up pulley 93 that is rotationally driven by the pulse motor 95 and the height of the paper stacking table 74 have a correspondence relationship. Therefore, by controlling the rotation direction and rotation angle of the pulse motor 95, the height of the sheet stacking base 74 can be adjusted and set.

  Further, a height sensor 98 is provided above the sheet trailing edge guide 76 to detect the upper surface of the sheet bundle when the upper surface of the sheet bundle on the sheet stacking table 74 reaches a predetermined height. By rotating the pulse motor 95 until the upper surface of the sheet bundle is detected by the height sensor 98, the upper surface of the sheet bundle on the sheet stacking board 74 is positioned at a predetermined height.

  In addition, assist fans 79 and 80 are provided outside the assist ducts 77 and 78, respectively. Each of the assist ducts 77 and 78 is a hollow body and has a ventilation path therein. Air sucked by each of the assist fans 79 and 80 is sent to the ventilation paths of the respective assist ducts 77 and 78. The air is blown out from the exhaust ports 78 a and 79 a of the assist ducts 77 and 78 to the inside of the outer frame 72 and blown to both end surfaces of the sheet bundle on the sheet stacking table 74.

  Next, the configuration of the paper drawer 75 will be described in detail. FIG. 5 is a perspective view showing the paper drawer portion 75 as viewed obliquely from the upper front. FIG. 6 is a perspective view showing the paper drawer portion 75 as viewed obliquely from above and behind, and FIG. 7 is a perspective view showing the paper drawer portion 75 as seen from diagonally below and rear.

  As shown in FIGS. 5 to 7, the paper drawing portion 75 includes four endless paper conveyance belts 81, a pair of rollers 82 and 83 that bridge the paper conveyance belts 81, an intake / exhaust fan 84, and an intake duct 85. And an exhaust duct 86 and the like.

  The intake duct 85 is a hollow body, and has an air suction path that is long in a direction orthogonal to the drawing direction (paper conveyance direction) E, and one end 85 a thereof is connected to the intake / exhaust fan 84. Then, as indicated by an arrow F, air is sucked from the air suction path of the intake duct 85 to the intake port (not shown) of the intake / exhaust fan 84 through the one side end 85a.

  The front end portion 85c and the rear end portion 85d of the intake duct 85 are formed with respective recesses 85h. The rollers 82 and 83 are disposed in these recesses 85h and are rotatably supported. The output shaft of the transport motor 97 is connected to the shaft of the front roller 82. Each paper transport belt 81 is stretched between the rollers 82 and 83, slightly separated from the upper plate 85 b of the intake duct 85, and is in contact with the bottom plate 85 g of the intake duct 85.

  Here, the front roller 82 is rotationally driven in the arrow direction D by the transport motor 97, the rear roller 83 is driven to rotate, and each paper transport belt 81 rotates in the arrow direction D. Further, air in the intake duct 85 is sucked by the intake / exhaust fan 84, and the air flows in through the air holes 81 a of the paper transport belt 81 and the air suction port of the bottom plate 85 g of the air intake duct 85, so The uppermost recording sheet of the sheet bundle is attracted to the surface of each sheet conveying belt 81, and the recording sheet is pulled out and conveyed by each sheet conveying belt 81.

  As shown in the cutaway perspective view of FIG. 8, five ribs 101a to 101e extending in the drawing direction E are formed on the bottom plate 85g of the intake duct 85, and each sheet conveying belt 81 is disposed between the ribs 101a to 101e. Has been. Further, between the ribs 101a to 101e, the lower surface of the bottom plate 85g of the intake duct 85 is a smooth curved surface 102 that protrudes downward, and each paper transport belt 81 is pressed against the curved surface 102 and deformed. The surface of each paper transport belt 81 is curved along each curved surface 102. Further, air suction ports 103 are formed in the curved surfaces 102 so as to overlap the plurality of air holes 81 a of the paper transport belt 81, and the air suction ports 103 are covered by the paper transport belts 81. In addition, a small suction assisting hole 104 is also formed in each curved surface 102 and each rib 101c to 101d.

  As shown in FIG. 9, when the air is sucked through the air holes 81 a of the paper transport belt 81, the air suction ports 103 of the intake duct 85, and the suction auxiliary holes 104, the recording paper Pa 1 is adsorbed on the surface of each paper transport belt 81. Is done. Then, a space is formed between the uppermost recording paper Pa1 that is directly attracted to the surface of each paper transport belt 81 and curved and the next recording paper Pa2 that is not directly attracted to the surface and is not curved, and each recording paper Pa1. The air reliably enters between Pa2 and Pa2, and the recording papers Pa1 and Pa2 are easily separated.

  On the other hand, as shown in FIGS. 5 to 7, the exhaust duct 86 is also a hollow body and has a long ventilation path in a direction orthogonal to the drawing direction E, and its one end 86 a is an intake / exhaust fan. As shown by an arrow K, air is sent from the exhaust port (not shown) of the intake / exhaust fan 84 to the ventilation path of the exhaust duct 86 through one end 86a of the exhaust duct 86.

  A plurality of exhaust ports 96 communicating with the ventilation path of the exhaust duct 86 are formed on the inner wall surface 86 d of the exhaust duct 86. An inner wall surface 86 d of the exhaust duct 86 is provided so as to overlap with an outer surface of a contact plate 72 b (shown in FIG. 4) of the outer frame body 72, and each exhaust port 96 of the exhaust duct 86 is a contact plate of the outer frame body 72. It faces the inside of the outer frame 72 through the notch 72c of 72b. When air is sent from the intake / exhaust fan 84 to the exhaust duct 86, this air is blown out from each exhaust port 96 toward the inside (rear) of the outer frame 72, and the leading end surface of the sheet bundle on the sheet stacking board 74. Be sprayed on.

  Further, the upper end portion of the exhaust duct 86 serves as a guide portion 87, and the guide portion 87 is positioned below each paper transport belt 81, and each paper transport belt 81 and the guide portion 87 are provided between each paper transport belt. It is an opening ES through which a recording sheet adsorbed and conveyed by the belt 81 passes. The guide portion 87 has a central portion 88 extending in a direction orthogonal to the recording paper conveyance direction (drawing direction E) and side portions 89 on both sides of the central portion 88. Each exhaust port 96 is distributed and provided directly below the central portion 88 and directly below each side portion 89.

  One side end 85a of the intake duct 85 and one side end 86a of the exhaust duct 86 are connected to the intake / exhaust fan 84, and the other side end 85f of the intake duct 85 and the other side of the exhaust duct 86 are connected. The end portions 86c are connected to each other, whereby the intake / exhaust fan 84, the intake duct 85, and the exhaust duct 86 are integrated.

  In the sheet feeding device 71 having such a configuration, as shown in the schematic cross-sectional view of FIG. 10, the sheet bundle is placed on the sheet stacking table 74, and the sheet bundle is placed on the column portion 76 a of the sheet trailing edge guide 76 and the outer frame body. The paper sheet is sandwiched between the assist ducts 77 and 78 and positioned. Then, each winding pulley 93 is rotated clockwise by the pulse motor 95 to raise the paper stacking table 74. When the upper surface of the paper bundle is detected by the height sensor 98, the pulse motor 95 is stopped and the paper bundle is turned on. The uppermost recording paper is positioned at a predetermined height. In addition, air is sent from the assist fans 79 and 80 to the assist ducts 77 and 78, and air is exhausted from the exhaust ports 77 a and 78 a of the assist ducts 77 and 78 toward the leading ends of both side surfaces of the sheet stack on the sheet stacking board 74. By blowing on the upper layer, air is allowed to enter between the recording sheets, and the recording sheets are dispersed. Further, air is sent from the intake / exhaust fan 84 to the exhaust duct 86, and air is blown from the respective exhaust ports 96 to the upper layer of the front end surface of the sheet bundle so that the air enters between the recording sheets, and the recording sheets are separated. I can catch it. As a result, the adhesion of each recording sheet in the upper layer of the sheet bundle is reduced, the recording sheet can be easily pulled out from the sheet bundle, and the recording sheets can be pulled out one by one.

  In this state, air is sucked from the air intake duct 85 to the air intake / exhaust fan 84, and air is sucked through the air holes 81a of the paper transport belt 81, the air suction port 103 of the bottom plate 85g of the air intake duct 85, and the suction auxiliary hole 104. The recording paper is sucked and adsorbed on the surface of each paper transport belt 81. At this time, a space is formed between the uppermost recording sheet that is directly adsorbed and curved on the surface of each sheet conveying belt 81 and the next recording sheet that is not directly adsorbed and curved on the surface. Air surely enters during the period. As a result, the adhesion of each recording sheet in the sheet bundle is reduced, and the recording sheet can be easily pulled out from the sheet bundle, and the recording sheets can be pulled out one by one.

  At the same time, the rollers 82 and 83 are rotated by the transport motor 97 to rotate the respective paper transport belts 81, and the recording paper is pulled out in the pull-out direction E by the respective paper transport belts 81 to the transport rollers 31 of the image forming apparatus 1. And the recording paper is conveyed through the conveyance path 33. When the recording sheet is conveyed to the conveying roller 31, the suction of air by the intake / exhaust fan 84 and the rotation of the rollers 82 and 83 by the conveying motor 97 are temporarily stopped, and the recording sheet is drawn out from the respective sheet conveying belts 81. Is completed, the suction of air by the intake / exhaust fan 84 and the rotation of the rollers 82 and 83 by the transport motor 97 are resumed, and the next recording paper is sucked onto the surface of each paper transport belt 81 to transport each paper. The recording paper is pulled out in the pulling direction E by the belt 81 and transported to the transport roller 31, and thereafter the recording paper is repeatedly adsorbed on the surface of each paper transporting belt 81, and the recording paper is pulled out by each paper transporting belt 81 in the same way Pull to E and carry.

  When the upper surface of the sheet bundle is lowered due to repeated drawing of the recording sheets, the pulse motor 95 is rotated until the upper surface of the sheet bundle is detected by the height sensor 98, so that the uppermost recording sheet of the sheet bundle is predetermined. Raise to height.

  By the way, in order to blow air from each exhaust port 96 onto the upper layer of the front end surface of the sheet bundle, it is necessary to position each exhaust port 96 at or near the same height as the upper surface of the sheet bundle. The opening 96 approaches each paper transport belt 81. Further, the exhaust ports 96 are distributed and provided directly below the central portion 88 of the guide portion 87 of the opening ES and directly below the side portions 89. For this reason, when each exhaust port 96 approaches each sheet conveyance belt 81, the guide portion 87 approaches each sheet conveyance belt 81.

  On the other hand, when the size of the recording paper is increased, both end portions PP of the recording paper P may hang down without being attracted by each paper conveying belt 81 as shown in FIG.

  If both end portions PP where the recording paper P hangs down are caught by the guide portions 87 that are close to the respective paper conveyance belts 81, a jam occurs.

  Specifically, as shown in FIG. 11, the distance between the outer ends of the two inner paper conveyance belts 81 is slightly narrower than the width of the standard postcard size, The distance is substantially the same as the width of the standard B5 size. Further, the width of the opening ES is slightly longer than the width of the standard A3 size. Therefore, when the recording paper P is approximately a standard postcard size, the entire recording paper P is adsorbed by the two inner paper conveyance belts 81, and both ends of the recording paper P do not hang down.

  However, when the recording paper P is of the standard B5 size, even if the recording paper P is adsorbed in the area A inside the curved apex s1 of each of the outer paper conveying belts 81, both end portions PP of the recording paper P are Air is bent downward along the curved surfaces of the respective outer sheet conveying belts 81 and outside the curved apex s1 and between the outer sheet conveying belts 81 and both ends PP of the recording sheet P. Becomes easy to leak. For this reason, both ends PP of the recording paper P hang down without being attracted outside the vicinity of each curved top portion s1, and in this state, the recording paper P is transported to the opening ES by each paper transport belt 81.

  Further, even when the recording paper P is the standard A4 size or the standard A3 size, since both end portions PP of the recording paper P protrude from the respective outer paper transport belts 81, the both end portions PP of the recording paper P hang down. The recording paper P is transported to the opening ES by each paper transport belt 81.

  Then, when both end portions PP where the recording paper P hangs down are caught by the guide portions 87 close to the respective paper conveying belts 81, a jam occurs.

  Therefore, in the paper feeding device 71 of the present embodiment, the upper surface shape of the guide part 87 of the opening ES is appropriately set so that the both end parts PP where the recording paper P hangs are not caught by the guide part 87.

  12 and 13 are a rear view and a perspective view showing the guide portion 87 of the opening ES. As shown in FIGS. 12 and 13, the upper surface 88 a of the central portion 88 of the guide portion 87 is a flat surface having a specified height, and is provided substantially in parallel with each paper conveying belt 81. Further, when the upper surface 89a of each side portion 89 is inclined so as to become lower as it is farther from the central portion 88 and reaches a certain height, the constant height from the portion s2 reaching the certain height to both ends of the guide portion 87 is constant. And is inclined so as to become higher as the distance from the entrance side of the recording paper in the opening ES increases, and so as to approach each paper transport belt 81 as the distance from the entrance side increases. The constant height is a height from a horizontal plane lower than the upper surface 89a of each side portion 89.

  For this reason, even if both ends PP of the recording paper P hang down, the both ends PP of the recording paper P enter the opening ES without being caught by the side portions 89 at the entrance side of the opening ES, and the recording paper P Both end portions PP are gradually lifted by the inclined upper surface 89a of each side portion 89 and brought close to each sheet conveying belt 81, and both end portions PP of the recording sheet P are adsorbed by each sheet conveying belt 81, and the recording sheet P The recording paper P is transported to the paper transport path 33 of the image forming apparatus 1 after the entire surface is substantially flat. As a result, the occurrence of a jam is more reliably prevented.

  In addition, as shown in FIG. 12, although the central portion 88 of the guide portion 87 is raised to be close to each paper transport belt 81, the central portion of the recording paper P is reliably adsorbed by each paper transport belt 81 and hangs down. Since it does not fall, the central portion of the recording paper P is not caught by the central portion 88 of the guide portion 87. For this reason, each exhaust port 96 directly below the central portion 88 of the guide portion 87 can also be brought close to each paper transport belt 81, and air from these exhaust ports 96 is blown onto the upper layer of the front end surface of the sheet bundle. The upper layer sheets can be dispersed well.

  FIG. 14 is a rear view showing a modified example of the guide portion 87 of the opening ES as viewed from the rear. In the guide portion 87A of this modified example, the upper surface 88a of the central portion 88 of the guide portion 87A is a flat surface having a specified height and is provided substantially in parallel with each paper transport belt 81, and the upper surface of each side portion 89 of the guide portion 87A. 89b is an inclined surface that becomes lower as the distance from the central portion 88 increases, and the upper surface 88a of the central portion 88 and the upper surface 89b of each side portion 89 form an isosceles trapezoid when the guide portion 87A is viewed from the back. . In addition, the boundary between the central portion 88 and each side portion 89 is positioned on the inner side of the curved top portion s1 of each of the sheet conveying belts 81 on both outer sides.

  For this reason, even if both ends PP of the recording paper P hang down outside the vicinity of each curved top portion s 1, the recording paper P does not get caught by the side portions 89 lower than the central portion 88, so that the recording paper P is not caught. P passes through the opening ES.

  FIG. 15 is a rear view showing a modification of the guide portion 87 of the opening ES as viewed from the rear. In the guide portion 87B of this modified example, the upper surface 88a of the central portion 88 of the guide portion 87B is a flat surface having a specified height, and is provided substantially in parallel with each paper transport belt 81. Further, when the upper surface 89c of each side portion 89 is inclined so as to become lower as it is away from the central portion 88 and reaches a certain height, the constant height from the portion s2 reaching the certain height to both ends of the guide portion 87B. Is maintained.

  Since the recording paper P has rigidity, as shown in FIG. 15, even if both ends PP hang down as shown in FIG. For this reason, even if the upper surface 89c of each side part 89 is not made lower than a certain height, the recording paper P passes through the opening ES without the both ends PP of the recording paper P being caught by each side part 89.

  Further, as shown in FIG. 15, since the height of the upper surface 89c of each side portion 89 is not remarkably lowered, each exhaust port 96 directly below each side portion 89 can be brought close to each sheet conveying belt 81, and these exhaust ports are provided. The air from 96 can be reliably blown to the upper layer of the front end surface of the sheet bundle, so that the upper sheets can be dispersed well.

  FIG. 16 is a front view showing another modification of the guide portion 87 of the opening ES. In the guide portion 87C of this modified example, the upper surface 88a of the central portion 88 of the guide portion 87C is a flat surface having a specified height and is provided substantially in parallel with each paper conveying belt 81, and the upper surface 89d of each side portion 89 is centered. It is lower than the upper surface 88a of the portion 88 and is provided substantially in parallel with each paper conveying belt 81, and a step is formed between the upper surface 88a of the central portion 88 and the upper surface 89d of each side portion 89.

  For this reason, even if both ends PP of the recording paper P hang down, the recording paper P passes through the opening ES without being caught by the side portions 89 of the opening ES.

  FIGS. 17A and 17B are a cross-sectional view and a bottom view showing a modification of the intake duct 85. In the intake duct 85A of this modified example, the bottom surface of the bottom plate 85i is flat, and the surface of each paper transport belt 81 disposed between the ribs 101a to 101e is also flat. When air is sucked through the air holes 81a of the paper transport belt 81, the air suction ports 103 of the air intake duct 85A, and the suction auxiliary holes 104, the recording paper P is adsorbed on the surface of each paper transport belt 81 and becomes flat. The recording paper P is conveyed to the opening ES.

  As described above, when the surface of each paper transport belt 81 is planar, the recording paper P is formed in the region C from the inner part of the outermost air suction port 103 to the both ends of the guide part 87A. Both end portions PP hang down, and the portion of the recording paper P adsorbed on the surface of each paper conveying belt 81 becomes flat in the region B between the inner portions of the outer end portions. Therefore, the upper surface 88a of the central portion 88 of the guide portion 87A is disposed in the region B, the upper surface 88a of the central portion 88 is provided as a flat surface having a specified height, and is provided substantially in parallel with each paper transport belt 81. The upper surface 89b of each side portion 89 is arranged in the outer regions C, and the upper surface 89b of each side portion 89 is inclined so as to become lower from the central portion 88, and each side portion 89 extends to both ends of the guide portion 87A. In the area.

  For this reason, even if both ends PP of the recording paper P hang down in the outer regions C, the both ends PP of the recording paper P pass through the opening ES without being caught by the side portions 89 lower than the central portion 88. .

  Even when the intake duct 85A in which the bottom surface of the bottom plate 85i is flat is applied, the central portion 88 is formed by combining the guide portion 87A, the guide portion 87B, and the guide portion 87C as shown in FIGS. If it is provided in the region B and each side part 89 is provided in the region C on both outer sides, the same effect can be obtained.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Document reader 11 Printing part 12 Paper conveyance part 13 Paper supply part 14 Large capacity paper feed cassette (LCC)
33 Paper transport path 71 Paper feeder 72 Outer frame body 73 Bottom plate 74 Paper stacking base 75 Paper drawer part 76 Paper rear end guides 77, 78 Assist ducts 79, 80 Assist fan 81 Paper transport belt (paper transport member)
82, 83 Roller 84 Intake / exhaust fan 85, 85A Intake duct 85i Bottom plate 86 Exhaust duct 87, 87A, 87B, 87C Guide portion 88 Central portion 89 Side portion 102 Curved surface (curved track portion)

Claims (8)

A paper feeding device that stacks a sheet bundle on a sheet stacking table, sucks air through a vent hole of a sheet conveying member, and sucks and conveys the sheets of the sheet bundle to the sheet conveying member,
Between the paper transport member and the guide portion disposed below the paper transport member is an opening through which the paper transported by the paper transport member passes,
The guide portion has a central portion extending in a direction orthogonal to the paper transport direction and each side portion on both sides of the central portion,
On the entrance side of the sheet of the opening, the side portions are made lower than the central portion ,
The air holes of the paper transport member are overlapped with a plurality of suction ports of the suction duct, and air is sucked into the suction duct through the air holes and the suction ports of the paper transport member,
Each of the side portions of the guide portion is provided in a region from a portion inside the outer end portion of the outermost suction ports of the suction ports to both ends of the guide portion. Paper feeder. A paper feeding device that stacks a sheet bundle on a sheet stacking table, sucks air through a vent hole of a sheet conveying member, and sucks and conveys the sheets of the sheet bundle to the sheet conveying member,
Between the paper transport member and the guide portion disposed below the paper transport member is an opening through which the paper transported by the paper transport member passes,
The guide portion has a central portion extending in a direction orthogonal to the paper transport direction and each side portion on both sides of the central portion,
On the entrance side of the sheet of the opening, the side portions are made lower than the central portion,
Smoothly curved in a direction perpendicular to the paper conveyance direction, and has a curved track portion that guides the paper conveyance member and curves the paper conveyance member;
Wherein each side of said guide portion includes a sheet feeding apparatus, wherein said than most outer sides of the curved top of the curved track portion provided from the inside of the site in the region of one end to the other end of the guide portion. A paper feeding device that stacks a sheet bundle on a sheet stacking table, sucks air through a vent hole of a sheet conveying member, and sucks and conveys the sheets of the sheet bundle to the sheet conveying member,
Between the paper transport member and the guide portion disposed below the paper transport member is an opening through which the paper transported by the paper transport member passes,
The guide portion has a central portion extending in a direction orthogonal to the paper transport direction and each side portion on both sides of the central portion,
On the entrance side of the sheet of the opening, the side portions are made lower than the central portion,
A plurality of outlets that blow out air in the direction of the sheet bundle are provided to be distributed directly below the central portion of the guide portion and directly below the side portions ,
Wherein said air outlet provided in each side are in the low have position than the air outlet provided in the central portion,
The plurality of air outlets are configured to blow air from the air holes in the direction of the sheet bundle using air sucked through the air holes of the paper conveying member. apparatus. A paper feeding device according to any one of claims 1 to 3 ,
The upper surface of each said side part of the said guide part inclined so that it might become so low that it left | separated from the said center part. A paper feeding device according to any one of claims 1 to 3 ,
Upper surface of each side of the guide portion, the constant reaches a certain height inclined to become lower than the extent away from said central portion, the portion thereof reaches said predetermined height from one end to the other end of the guide portion A paper feeder characterized by maintaining the height. The sheet feeding device according to claim 4 or 5 ,
The upper surface of each said side part of the said guide part inclined so that it might become so high that it spaced apart from the entrance side of the said sheet | seat of the said opening part. A paper feeding device according to any one of claims 1 to 3 ,
Sheet feeding apparatus, characterized in that the said guide portion between the central portion and each side, wherein each side is provided with a step which is lower than the central portion. An image forming apparatus comprising the paper feeding device according to claim 1 .

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