JP5479433B2 - Paper feeding device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a sheet feeding device that draws out and feeds a sheet from a bundle of sheets stacked on a sheet loading table, and an image forming apparatus including the sheet feeding device.

  An example of this type of paper feeding device is disclosed in Patent Document 1. Here, a plurality of suction conveyance belts are arranged side by side, air is sucked through the suction holes of each suction conveyance belt, paper is sucked to each suction conveyance belt, and each suction conveyance belt is moved around to convey the paper. doing. In addition, a plurality of ribs projecting downward through the gaps between the suction conveyance belts are provided on the guide surface that is in sliding contact with the inner peripheral surface of each suction conveyance belt, and the sheet sucked by each suction conveyance belt is brought into contact with each rib. Thus, the paper is curved (undulated), and a space is formed between the sucked paper and the next paper to prevent double feeding of each paper.

Japanese Patent Laid-Open No. 4-358637

  However, when the sheet is curved by bringing the sheet into contact with each rib protruding downward from between the suction conveyance belts as in Patent Document 1, the curved sheet and each of the suction conveyance belts that are not curved are used. There is a gap between them. For this reason, air is sucked from the vicinity of the leading end of the sheet into the gap, and the next sheet is sucked by the suction of the air, that is, the next sheet is sucked near the leading end of the sheet, and this is the double feed of each sheet. Caused.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and provides a paper feeding device capable of more effectively preventing paper double feeding and an image forming apparatus including the paper feeding device. Objective.

In order to solve the above-described problem, a paper feeding device according to the present invention stacks a sheet bundle on a sheet stacking table, and arranges a plurality of sheet conveying members in a direction orthogonal to the sheet conveying direction of the sheet bundle, Is a paper feeding device that sucks and conveys the sheet onto the surface of each sheet conveying member, and includes a guide unit that guides each sheet conveying member, The guide portions are formed side by side in the orthogonal direction, smoothly curved in the orthogonal direction, and a plurality of curved portions that are in sliding contact with the back surface opposite to the front surface of each paper transport member, and each paper transport Ribs positioned between the members and projecting from the gaps between the paper transport members and flush with the surface of the paper transport members.
In the sheet feeding device of the present invention, a sheet bundle is stacked on a sheet stacking table, a plurality of sheet conveying members are arranged in parallel in a direction perpendicular to the sheet conveying direction of the sheet bundle, and air is supplied to each sheet conveying member. A sheet feeding device that sucks and conveys the sheet onto the surface of each of the sheet conveying members, and includes a guide unit that guides each of the sheet conveying members. Formed side by side in an orthogonal direction, smoothly curved in the orthogonal direction, and having a plurality of curved portions that are in sliding contact with the back surface opposite to the front surface of each paper transport member, each curved portion from the curved surface And the curved portion with which the outermost sheet conveying member in the orthogonal direction among the plurality of sheet conveying members is slidably contacted is a top portion protruding toward the sheet conveying member and the orthogonal direction from both sides of the top portion. A curved surface having continuous troughs. , The curved portion extends in a direction the perpendicular from the center of the outermost sheet transport members in sliding contact with the said curved portion to the outer end of the paper conveying member.

  In the present invention, since the back surface of the paper transport member is in sliding contact with the curved portion that smoothly curves in the direction orthogonal to the paper transport direction, the surface of the paper transport member is curved in the same manner as the curved portion, and the paper transport member The sheet adsorbed on the surface of the sheet is also bent in the same manner as the bending portion. For this reason, a space is formed between the curved sheet adsorbed on the surface of the sheet conveying member and the next sheet that is not curved, and each sheet is separated to prevent the multiple sheets from being fed. In addition, since the sheet conveying member and the sheet are curved in the same manner as the curved portion, it is difficult to form a gap between the sheet conveying member and the sheet, and air may be sucked into the gap from the front end of the sheet. Therefore, there is no occurrence of double feeding due to air suction near the leading edge of the paper.

Also, by providing a plurality of paper conveying members and a plurality of curved portions, the surface of each paper conveying member is curved at a plurality of locations, the paper is also curved at a plurality of locations, and a plurality of locations between one paper and the next paper A space is formed in the sheet, and the double feeding of each sheet is surely prevented. Further, even if the size of the paper is small, the paper is surely curved, and a space between the paper and the next paper is reliably formed, thereby preventing the double feeding of each paper.

  Further, in the paper feeding device of the present invention, the arrangement interval of the curved portions is made wider than the arrangement interval of the paper transport members.

  Under such conditions, the number of the curved portions is suppressed, and one or a plurality of paper transporting members are in sliding contact with one curved portion, and the surface of each paper transporting member is favorably curved along the curved portions. . As a result, the sheet is satisfactorily attracted to the surface of each sheet conveying member.

  In the paper feeding device of the present invention, the width of each of the curved portions in the direction orthogonal to the sheet conveyance direction is such that the curved portion near the center of the paper is closer to both sides of the paper. Longer than.

  As a result, a wide curved portion is formed near the center of the sheet adsorbed on the surface of the sheet conveying member, and a large wide space is formed between the vicinity of the center of the sheet and the next sheet. It becomes easy to separate, and the double feed of each paper is more effectively prevented.

  Furthermore, in the paper feeding device of the present invention, the plurality of paper transport members are in sliding contact with the curved portion having the longer width.

  Thereby, even if the width of the bending portion is long, the surface of each sheet conveying member that is smoothly curved along the bending portion can be formed.

  In the sheet feeding device according to the present invention, the height from the valley portion to the top portion of each curved portion is lower in the curved portions near both sides of the paper than in the curved portions near the center of the paper. .

  As a result, the height of the curved portion near the center of the sheet adsorbed on the surface of the sheet conveying member increases, and a large space is formed between the vicinity of the center of this sheet and the next sheet, and each sheet is further separated. It becomes easy and the double feed of each paper is prevented more effectively.

  Furthermore, in the paper feeding device of the present invention, the guide portion is located between the paper transport members, protrudes from the gaps of the paper transport members, and is flush with the surface of the paper transport members. It has a rib.

  By providing such ribs, the surface of each sheet conveying member and the end face of the ribs become a sheet adsorbing surface smoothly connected, and the sheet is adsorbed better.

  In the paper feeding device of the present invention, the curved portion is provided with an air suction port that overlaps and communicates with the plurality of air holes of the paper conveying member.

  As a result, air is sucked from the vent hole of the sheet conveying member to the air suction port of the curved portion.

  Furthermore, in the paper feeding device of the present invention, an air suction path for sucking air through the air suction port is provided in a direction orthogonal to the paper transport direction.

  Thereby, the air suction path can be provided in a straight line, and the structure of the air suction path can be simplified.

  In the paper feeding device of the present invention, an air blowing unit that blows air onto the front end surface of the sheet bundle is provided.

  When air is blown to the front end surface of the sheet bundle in this way, air quickly enters the space formed between the curved sheet adsorbed on the surface of the sheet conveying member and the next sheet that does not curve, Each sheet is more easily separated, and multiple feeding of each sheet is more effectively prevented.

  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.

  In the present invention, since the back surface of the paper transport member is in sliding contact with the curved portion that smoothly curves in the direction orthogonal to the paper transport direction, the surface of the paper transport member is curved in the same manner as the curved portion, and the paper transport member The sheet adsorbed on the surface of the sheet is also bent in the same manner as the bending portion. For this reason, a space is formed between the curved sheet adsorbed on the surface of the sheet conveying member and the next sheet that is not curved, and each sheet is separated to prevent the multiple sheets from being fed. In addition, since the sheet conveying member and the sheet are curved in the same manner as the curved portion, it is difficult to form a gap between the sheet conveying member and the sheet, and air may be sucked into the gap from the front end of the sheet. Therefore, there is no occurrence of double feeding due to air suction near the leading edge of the paper.

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. 4 is a perspective view showing a paper drawer portion of the paper feeding device as 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. It is sectional drawing which shows a paper feeding apparatus roughly. FIG. 4 is a perspective view showing the air intake duct and each paper transport belt of the paper supply device, as viewed from the front, broken in a direction perpendicular to the recording paper drawing direction. FIG. 4 is a cross-sectional view showing the guide bottom plate of the air intake duct and each paper transport belt, as viewed from the front, broken in a direction orthogonal to the recording paper drawing direction. It is sectional drawing which expands and shows the rib and paper conveyance belt of FIG. FIG. 11 is a cross-sectional view schematically illustrating a guide bottom plate, each sheet conveyance belt, and a recording sheet of the intake duct of FIG. 10. FIG. 10 is a cross-sectional view showing a guide bottom plate and each paper transport belt of an intake duct according to a modification, as viewed from the front, broken in a direction perpendicular to the recording paper drawing direction.

  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 color 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 orthogonal to the drawing direction E, and are moved so as to approach each other or interlock so as to be separated from each other. Moved.

  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 is formed with a large number of air holes 81 a, and air is sucked from the air holes 81 a of each paper transport belt 81 to the intake / exhaust fan 84 through the intake duct 85. 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 drawing direction E (backward).

  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. As shown in FIG. 4, 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 77a and 78a of the assist ducts 77 and 78 to the inside of the outer frame 72.

  As shown in FIGS. 2 and 4, the paper trailing edge guide 76 can reciprocate along the recording paper drawing direction E, and is positioned at an arbitrary position in the drawing direction E. Further, as shown in FIGS. 2 and 4, each of the assist ducts 77 and 78 can reciprocate in a direction orthogonal to the drawing direction E, and is positioned at an arbitrary position in the direction orthogonal to the drawing direction E.

  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 87 are connected to the protruding pieces 74 c on one side of the paper stacking base 74, and each wire 87 is hooked around a plurality of driven pulleys 88 and drawn around a take-up pulley 89. It is connected. On the other side of the outer frame 72, the other two wires 87 are connected to the protruding pieces 74c on the other side of the sheet stacking table 74, and the other wires 87 are connected to a plurality of other driven pulleys 88. It is drawn around and connected to another take-up pulley 89. Each winding pulley 89 is fixed to both ends of a common shaft 91 that is rotatably supported. The shaft 91 is rotationally driven by a pulse motor 92 to rotate each winding pulley 89, and each wire 87 is wound to each winding 87. It is wound around the pulley 89 and is fed out from each winding pulley 89.

  When the shaft 91 is rotationally driven by the pulse motor 92 and each take-up pulley 89 is rotated in the clockwise direction, each wire 87 is taken up by each take-up pulley 89, the paper stacking table 74 is raised, and each take-up pulley 89 is also turned up. When the take-up pulley 89 is rotated in the counterclockwise direction, each wire 87 is fed out from each take-up pulley 89, and the sheet stacking table 74 is lowered. Further, the rotation angle of the take-up pulley 89 that is rotationally driven by the pulse motor 92 and the height of the paper stacking base 74 are in a corresponding relationship. Therefore, by controlling the rotation direction and rotation angle of the pulse motor 92, the height of the sheet stacking base 74 can be adjusted and set.

  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, 6, and 7, the paper drawer 75 includes four endless paper transport belts 81, a set of rollers 82 and 83 that bridge the paper transport belts 81, an intake / exhaust fan 84, An intake duct 85 and an exhaust duct 86 are provided.

  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 93 is connected to the shaft of the front roller 82. Each sheet conveying belt 81 is stretched between the rollers 82 and 83, slightly separated from the upper surface 85 b of the intake duct 85, and is in contact with the lower surface 85 g of the intake duct 85.

  Further, an air suction port (shown in FIGS. 9 and 10) is provided on the lower surface 85 g of the intake duct 85 for each of the sheet conveying belts 81 so as to overlap the plurality of air holes 81 a of the sheet conveying belt 81.

  Here, the front roller 82 is rotationally driven in the arrow direction D by the transport motor 93, the rear roller 83 is driven to rotate, and each paper transport belt 81 rotates in the arrow direction D. In addition, air in the intake duct 85 is sucked by the intake / exhaust fan 84, and the air flows into the air suction port on the lower surface 85g of the intake duct 85 and the air holes 81a of the paper transport belt 81, and the recording paper is transported to each paper. The sheet is adsorbed on the surface of the belt 81, and the recording sheet is conveyed by each sheet conveying belt 81.

  On the other hand, the exhaust duct 86 is also a hollow body and has a long ventilation path in a direction orthogonal to the drawing direction E. One end 86a of the exhaust duct 86 is connected to the intake / exhaust fan 84 and is indicated by an arrow K. As described above, 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 the one end 86a of the exhaust duct 86.

  Further, each exhaust port 86 b communicating with the ventilation path of the exhaust duct 86 is 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 86 b 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, the air is blown out from the exhaust ports 86 b to the inner rear side of the outer frame 72.

  Further, one end 85a of the intake duct 85 and one 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 paper feeding device 71 having such a configuration, as shown in the schematic cross-sectional view of FIG. 8, the paper bundle is placed on the paper stacking base 74, and the paper bundle is placed on the column portion 76 a of the paper trailing edge guide 76 and the outer frame. The paper sheet is sandwiched between the assist ducts 77 and 78 and positioned. Then, each winding pulley 89 is rotated in the clockwise direction by the pulse motor 92 to raise the paper stacking base 74, and the uppermost recording paper in the paper bundle is positioned at a predetermined height. Further, air is sent from the assist fans 79 and 80 to the assist ducts 77 and 78, and the air is exhausted from the exhaust ports 77 a and 78 a of the assist ducts 77 and 78 on both side end surfaces near the leading edge of the sheet stack on the sheet stacking board 74. Air is blown onto the upper layer to allow air to enter between the recording sheets, thereby causing the recording sheets to vary. Further, air is sent from the intake / exhaust fan 84 to the exhaust duct 86, and air is blown from the exhaust holes 86b of the exhaust duct 86 to the upper layer of the leading end surface of the sheet bundle, so that the air enters between the recording sheets, and each recording sheet. Disperse the paper. 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 the air is sucked through the air suction ports 111 and 112 on the lower surface 85g of the air intake duct 85 while the air is sucked into the air suction duct 85. When the rollers 82 and 83 are intermittently rotated to move each paper conveyance belt 81 intermittently, the recording paper is attracted to the surface of each paper conveyance belt 81, and the recording paper is fed by each paper conveyance belt 81. Pulled in the drawing direction E and conveyed to the conveying roller pair 31 of the image forming apparatus 1, the recording sheet is conveyed through the conveying path 33, and the next recording sheet is subsequently adsorbed on the surface of each sheet conveying belt 81, The recording paper is pulled out in the drawing direction E by each paper transport belt 81 and transported to the transport roller pair 31. There is adsorbed, the recording sheet by the sheet conveying belt 81 is gradually is transported drawn in the drawing direction E.

  By the way, in the paper feeding device 71, air is blown from the exhaust ports 77a and 78a of the assist ducts 77 and 78 and the exhaust holes 86b of the exhaust duct 86 to the both side end surfaces and the front end surface of the sheet bundle, so that each recording sheet is discharged. Although it is scattered, a plurality of recording sheets may still be pulled out while overlapping each other on the surface of each sheet conveying belt 81. If such a phenomenon is left unattended, double feeding of recording sheets occurs.

  Therefore, in the present embodiment, the surface of each paper transport belt 81 is curved (wavy) in a direction perpendicular to the recording paper drawing direction (paper transport direction) E. For this reason, the recording paper adsorbed on the surface of each paper conveyance belt 81 is similarly bent, and the recording sheet adsorbed and curved on the surface of each paper conveyance belt 81 and the next recording that is not directly adsorbed on the surface and does not curve. A space is formed between the recording sheets and the recording sheets are separated. Thereby, double feeding of each recording sheet is prevented.

  Further, since each paper conveyance belt 81 and the recording paper adsorbed on the surface of each paper conveyance belt 81 are similarly curved, no gap is formed between them, and from the vicinity of the leading edge of the recording paper to such a gap. And air is not sucked, and double feeding due to air suction near the leading edge of the recording paper does not occur.

  Next, a configuration for bending the surface of each paper transport belt 81 in a direction perpendicular to the recording paper drawing direction (paper transport direction) E will be described in detail.

  FIG. 9 is a perspective view showing the air intake duct 85 and the respective paper transport belts 81 as viewed from the front side by breaking in a direction perpendicular to the recording paper drawing direction E. FIG. FIG. 10 is a cross-sectional view showing the guide bottom plate 102 and each paper transport belt 81 of the air intake duct 85 in the same direction as FIG.

  As shown in FIGS. 9 and 10, an air suction path 103 extending in a direction orthogonal to the drawing direction E is formed between the top plate 101 and the guide bottom plate 102 of the intake duct 85, and the end of the air suction path 103 is a partition wall 104. It is blocked by. Each paper transport belt 81 is slightly separated from the upper surface 85 b of the top plate 101 and is in contact with the lower surface 85 g of the guide bottom plate 102.

  On the lower surface 85 g of the guide bottom plate 102, five ribs 105 a to 105 e extending in the drawing direction E are formed and protrude downward, and the interval between the ribs 105 a to 105 e substantially matches the width of each paper transport belt 81. The paper transport belts 81 are disposed and sandwiched between the ribs 105a to 105e.

  Between the ribs 105a and 105b on one end side, the lower surface 85g of the guide bottom plate 102 is a smooth curved surface 106 that protrudes generally downward. Also, the lower surface 85g of the guide bottom plate 102 is a smooth curved surface 107 that protrudes generally downward between the ribs 105e and 105d on the other end side. Each of the curved surfaces 106 and 107 is a flat surface or a slightly recessed surface near both sides of the curved surface, but it can be said that the curved surfaces 106 and 107 as a whole protrude substantially downward.

  Furthermore, in the range of the three ribs 105b, 105c, and 105d closer to the center, the lower surface 85g of the guide bottom plate 102 is a smooth curved surface 108 that is recessed upward.

  Each sheet conveying belt 81 has elasticity, and each sheet conveying belt 81 is stretched between the rollers 82 and 83 so that each sheet conveying belt 81 has a lower surface 85g (each curved surface 106, 107, 108) of the intake duct 85. Is in pressure contact. Therefore, each paper transport belt 81 is deformed along each curved surface 106, 107, 108, and the surface of each paper transport belt 81 is curved along each curved surface 106, 107, 108.

A plurality of air suction ports 111 are formed on the curved surfaces 106 and 107 on both sides, and a plurality of air suction ports 112 and 113 are also formed on the central curved surface 108 . The width of the formation area of each air suction port 111, 112, 113 is narrower than the width of each paper transport belt 81, and each air suction port 111, 112, 113 is covered by each paper transport belt 81. Further, each of the air suction ports 111, 112, 113 overlaps with the plurality of vent holes 81 a of the paper transport belt 81. For this reason, air is sucked into the air suction path 103 of the intake duct 85 through the air holes 81 a and the air suction ports 111, 112, and 113 of the paper transport belt 81 while the paper transport belt 81 is revolving. Can do.

  In addition, not only each curved surface 106-108 but each rib 105b, 105c, 105d is supplemented with the small air suction hole 114. FIG.

  Further, as shown in an enlarged view in FIG. 11, the height hr of each of the ribs 105a to 105e and the thickness hb of each of the paper transport belts 81 are made substantially equal, and the end face facing downward of each of the ribs 105a to 105e and each paper. The surface of the transport belt 81 is flush with each other to form a smooth curved surface in which the end surfaces of the ribs 105a to 105e and the surface of the paper transport belt 81 are continuous.

Further, as shown in FIG. 9, the width w2 (= 33 mm) of each of the curved surfaces 106 and 107 on both sides in the direction orthogonal to the drawing direction E is slightly narrower than the width of the sheet conveying belt 81. 107 , one sheet conveying belt 81 is in sliding contact with each other. Further, the width w1 (= 115 mm) of the central curved surface 108 in the direction orthogonal to the drawing direction E is wider than twice the width of the paper conveying belt 81, and two paper conveying belts are provided on the curved surface 108. 81 is in sliding contact. In other words, the average arrangement interval (pitch) of the curved surfaces 106 to 108 is wider than the arrangement interval (pitch) of the paper conveying belts 81, thereby suppressing the number of the curved surfaces 106 to 108. In addition, one or a plurality of paper transport belts 81 are in sliding contact with one curved surface.

Further, as shown in FIG. 10, the height h2 (= 2 mm) from the trough to the top of each curved surface 106, 107 on both sides is the height h1 (= 3 mm) from the trough to the top of the central curved surface 108. ) Is lower than. Thereby, the curvature of each curved surface 106, 107 on both sides is suppressed, and even with a single paper conveyance belt 81, the paper conveyance belt 81 is well curved along each curved surface 106, 107 . Moreover, since the two paper transport belt 81 in the center of the curved surface 108 is in sliding contact, it is possible to form the surface of the sheet conveying belt 81 smoothly curved along the center of the curved surface 108. As a result, the surfaces of all the paper transport belts 81 are favorably curved along the curved surface, and the recording paper is easily adsorbed on the surfaces of the respective paper transport belts 81.

In such a configuration, as shown in the cross-sectional view of FIG. 12, air is sucked from the intake duct 85 to the intake / exhaust fan 84, and the air is sucked into the air holes 81a of the paper transport belt 81 and the air suction of the intake duct 85. When sucked through the mouths 111, 112, 113 and the air suction port 114 of the rib, the recording paper Pa 1 is adsorbed on the surface of each paper transport belt 81, and the recording paper Pa 1 is curved along the surface of each paper transport belt 81. (Rippling). For this reason, even if a plurality of recording papers Pa1 and Pa22 are pulled up while being superposed on the surface of each paper transport belt 81, the uppermost recording paper Pa1 that is directly attracted to the surface of each paper transport belt 81 and curved A space is formed between the recording sheet Pa2 and the next recording sheet Pa2 that is not directly attracted to the surface and is not curved. In particular, since the central curved surface 108 is wide and high in height, a wide and high curved surface is formed near the center of the recording paper adsorbed on the surface of each paper conveying belt 81 curved along the curved surface 108. Thus, a large wide space is formed between the vicinity of the center of the recording sheet and the next recording sheet.

  In this state, when air is blown from the exhaust holes 86b of the exhaust duct 86 to the upper layer of the front end surface of the sheet bundle, the air quickly enters the space formed between the recording sheets Pa1 and Pa2, and the recording sheet Pa2 leaves the recording paper Pa1 promptly. In particular, a large amount of air enters a large space formed near the center of the recording paper Pa1 and the next recording paper Pa2, and each recording paper Pa1, Pa2 is immediately separated from the center. For this reason, double feeding of the recording papers Pa1 and Pa2 is effectively prevented.

Each of the paper conveying belts 81 is curved at three locations according to the three curved surfaces 106 to 108, and the uppermost recording paper Pa1 is also curved at three locations, and between the recording paper Pa1 and the next recording paper Pa2. Since a plurality of spaces are formed, double feeding of the recording papers Pa1 and Pa2 is reliably prevented. Furthermore, even if the size of the recording paper is small, the recording paper is curved along at least one curved surface 108 , and a space between the recording paper and the next recording paper is formed reliably. Double feed is prevented.

  Further, since each paper transport belt 81 and the recording paper Pa1 are curved in the same manner as the curved surfaces 106 to 108, no gap is formed between each paper transport belt 81 and the recording paper Pa1, and the vicinity of the front end of the recording paper Pa1. Thus, air is not sucked into such a gap, and double feeding due to air suction near the leading edge of the recording paper Pa1 does not occur.

  Further, the ribs 105b to 105d are arranged between the paper conveying belts 81, and the end surfaces of the ribs 105a to 105e and the surfaces of the paper conveying belts 81 are continuously smooth curved surfaces. Is better adsorbed. Furthermore, the arrangement of the ribs 105b to 105d makes it difficult for air to be sucked from the vicinity of the front end of the recording paper Pa1 to the gap between the respective paper transport belts 81, and this also causes the air near the front end of the recording paper Pa1 to be sucked. The occurrence of double feed due to suction is prevented.

  FIG. 13 is a cross-sectional view of the guide bottom plate 102A and each paper transport belt 81 of the intake duct 85, which is a modified example, cut away in a direction perpendicular to the recording paper drawing direction E and viewed from the front. In FIG. 13, the same reference numerals are given to portions that perform the same operations as those in FIGS. 9 and 10.

  In the intake duct 85A of this modified example, five ribs 105a to 105e extending in the pull-out direction E are formed on the lower surface 85g of the guide bottom plate 102A, and each paper transport belt 81 is disposed between the ribs 105a to 105e. It is sandwiched between.

  Between the ribs 105a to 105e, the lower surface 85g of the guide bottom plate 102A is a smooth curved surface 121 protruding downward, and the four curved surfaces 121 between the ribs 105a to 105e have the same shape and the same. Size. Each sheet conveying belt 81 is deformed by being pressed against each curved surface 121, and the surface thereof is curved along each curved surface 121.

  Each curved surface 121 is formed with an air suction port 122, and each air suction port 122 is covered with each paper transport belt 81. Each air suction port 122 overlaps the plurality of vent holes 81 a of each paper transport belt 81.

  Further, the height of each rib 105a to 105e and the thickness of each paper transport belt 81 are substantially equal, and the end surface of each rib 105a to 105e and the surface of each paper transport belt 81 are flush with each other. A smooth curved surface in which the end surfaces of 105a to 105e and the surface of each paper transport belt 81 are continuous is formed.

  Even in such a configuration, when the air is sucked through the air holes 81a of the paper transport belt 81 and the air suction ports 122 of the intake duct 85, the recording paper Pa1 is adsorbed on the surface of the paper transport belt 81, and the recording paper. Pa1 is curved (undulated) along the surface of each paper conveying belt 81. For this reason, a space is formed between the recording sheet 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 does not curve, and each recording paper Pa1, Pa2 is formed. Leave. In addition, air from the exhaust ports 77a and 78a of the assist ducts 77 and 78 and the exhaust holes 86b of the exhaust duct 86 is quickly blown into the space between the recording sheets, and the recording sheet Pa2 is separated from the recording sheet Pa1. Thereby, double feeding of the recording papers Pa1 and Pa2 is prevented.

  Each of the paper conveying belts 81 is curved at four locations according to the four curved surfaces 121, the recording paper Pa1 is also curved at four locations, and spaces are provided at four locations between the recording paper Pa1 and the next recording paper Pa2. Is formed, and the double feeding of the recording papers Pa1 and Pa2 is surely prevented. Even if the size of the recording paper is small, the recording paper is curved along at least one curved surface 121, so that a space is reliably formed between the recording paper and the next recording paper. Is prevented.

  Further, since each paper conveyance belt 81 and the recording paper Pa1 are curved in the same manner as each curved surface 121, no gap is formed between each paper conveyance belt 81 and the recording paper Pa1, and from the vicinity of the leading end of the recording paper Pa1 No air is sucked into such a gap, and double feeding due to air suction near the leading edge of the recording paper Pa1 does not occur.

  Further, the ribs 105b to 105d are arranged between the paper conveying belts 81, and the end surfaces of the ribs 105a to 105e and the surfaces of the paper conveying belts 81 are continuously smooth curved surfaces. Is better adsorbed. Further, the arrangement of the ribs 105a to 105e prevents air from being sucked from the vicinity of the front end of the recording paper Pa1 into the gap between the respective paper transport belts 81, and this also causes the air in the vicinity of the front end of the recording paper Pa1. The occurrence of double feed due to suction is prevented.

  In addition, since the central portion of each curved surface 121 protrudes downward (outward), each paper transport belt 81 that is in sliding contact with each curved surface 121 is difficult to come off as it moves toward the center of each curved surface 121. On the other hand, when the central portion of each curved surface 121 is recessed inward, each paper transport belt 81 that is in sliding contact with each curved surface 121 is likely to come off in an attempt to move to the end of each curved surface 121.

  In the above embodiment, the ribs 105b to 105d are arranged between the paper transport belts 81, but the ribs 105b to 105d are omitted to narrow the gaps between the paper transport belts 81. It doesn't matter.

  Further, although the paper stacking table 74 is raised and lowered, instead of this, each paper transport belt 81 may be lifted or lowered, and the paper stacking table 74 and each paper transport belt 81 may be lifted and lowered.

  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)
71 Paper feeder 72 Outer frame 73 Bottom plate 74 Paper stacking board 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 86 Exhaust duct 92 Pulse motor 101 Top plate 102, 102A Guide bottom plate (guide portion)
103 Air suction path 104 Partition walls 105a to 105e Ribs 106, 107, 108, 121 Curved surface (curved portion)
111, 112, 122 Air suction port

Claims (11)

The sheet bundle is stacked on a sheet stacking table, a plurality of sheet conveying members are arranged in a direction perpendicular to the sheet conveying direction of the sheet bundle, and air is sucked through the vent holes of the respective sheet conveying members, and the sheet A sheet feeding device that attracts and conveys the sheet to the surface of each sheet conveying member,
A guide portion for guiding each of the sheet conveying members;
The guide portions are formed side by side in the orthogonal direction, smoothly curved in the orthogonal direction, and a plurality of curved portions that are in sliding contact with the back surface opposite to the front surface of each paper transport member, and each paper transport A sheet feeding device comprising ribs positioned between members and protruding from a gap between the sheet conveying members and flush with a surface of each sheet conveying member. The sheet bundle is stacked on a sheet stacking table, a plurality of sheet conveying members are arranged in a direction perpendicular to the sheet conveying direction of the sheet bundle, and air is sucked through the vent holes of the respective sheet conveying members, and the sheet A sheet feeding device that attracts and conveys the sheet to the surface of each sheet conveying member,
A guide portion for guiding each of the sheet conveying members;
The guide portion is formed side by side in the orthogonal direction, has a plurality of curved portions that are smoothly curved in the orthogonal direction, and are in sliding contact with the back surface opposite to the front surface of each paper conveying member,
Each of the curved portions is a curved surface,
The curved portion with which the outermost sheet conveying member in the orthogonal direction among the plurality of sheet conveying members is slidably contacted is a peak protruding to the sheet conveying member and a valley continuous in the orthogonal direction from both sides of the top. A curved surface having a portion,
The paper feeding device, wherein the curved portion extends in the orthogonal direction from the center of the outermost paper conveying member in sliding contact with the curved portion to the outer end of the paper conveying member . The sheet feeding device according to claim 1 or 2,
The paper feeding device according to claim 1, wherein an interval between the curved portions is wider than an interval between the paper conveying members. The sheet feeding device according to any one of claims 1 to 3,
The width of each of the curved portions in the direction orthogonal to the sheet conveyance direction is such that the curved portion near the center of the paper is longer than the curved portions near both sides of the paper. . The sheet feeding device according to claim 4,
The sheet feeding device, wherein the plurality of sheet conveying members are in sliding contact with the curved portion having the longer width. The sheet feeding device according to any one of claims 1 to 5,
The height from the trough part to the top part of each curved part is lower in the curved part near both sides of the paper than in the curved part near the center of the paper. The sheet feeding device according to claim 2,
The guide portion includes ribs that are positioned between the paper transport members, protrude from gaps between the paper transport members, and are flush with the surface of the paper transport members. Paper device. The sheet feeding device according to any one of claims 1 to 7,
The sheet feeding device according to claim 1, wherein an air suction port that overlaps and communicates with the plurality of air holes of the sheet conveying member is provided in the curved portion. The sheet feeding device according to claim 8,
An apparatus for feeding air, wherein an air suction path for sucking air through the air suction port is provided in a direction orthogonal to a transport direction of the paper. A sheet feeding device according to any one of claims 1 to 9,
A paper feeding device comprising an air blowing unit that blows air onto a front end surface of the sheet bundle.   An image forming apparatus comprising the paper feeding device according to claim 1.

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