JP5505908B2 - 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 transport belts are arranged side by side, air is sucked through the suction holes of each suction transport belt, the paper is sucked into each suction transport belt, and each suction transport belt is moved around to transport the paper. ing. 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 sheets sucked by the suction conveyance belts are brought into contact with the ribs. Thus, the paper is curved (undulated), and a space is formed between this paper and the next paper, and each paper is dispersed to prevent double feeding of the paper.

Japanese Patent Laid-Open No. 4-358637

  However, in Patent Document 1, the protruding length of each rib downward from the gap of each suction conveyance belt is constant, and the degree of curvature of the paper that is attracted to the surface of each suction conveyance belt and contacts each rib is also constant. It is. For this reason, depending on the type of paper, the paper sucked on the surface of each suction conveyance belt and the next paper do not vary well, and double feeding of the paper occurs. For example, when the thickness of the paper is thin, the adhesiveness of each paper is high, so that the paper sucked on the surface of each suction conveyance belt is curved and a space is formed between this paper and the next paper. However, if this space is small, the sheets are difficult to separate, and sheet multi-feeding easily occurs. In addition, even when the moisture content of the paper is large or the charge amount of the paper is large, the adhesiveness of each paper is high, so that the paper sucked on the surface of each suction conveyance belt and the next paper If the space is small, it is difficult to separate the sheets, and sheet multi-feeding easily occurs.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and a paper feeding device capable of more reliably separating a paper adsorbed on a paper conveying belt and a next paper and an image including the same. An object is to provide a forming apparatus.

In order to solve the above problems, the sheet feeding apparatus of the present invention, there is provided a sheet feeding apparatus for conveying by suction the paper on the surface of the paper conveying belt by sucking air through the vent holes of the paper conveying belt, the surface of the paper conveying belt is curved in the direction perpendicular to the conveying direction of the sheet, the curvature setting changing unit for changing a curvature of the sheet conveying belt surface, and a controller for controlling the curvature setting change unit, the paper and a guide portion for guiding the conveyor belt, wherein the guide portion extends in the transport direction and adjacent to the side edge of the sheet conveying belt, projecting from the surface of the guide portion on the side of the sheet conveying belt Has ribs.

In the present invention, the adsorption of the surface of the sheet conveying belt on which is curved in the direction perpendicular to the conveying direction of the sheet can be controlled by changing the curvature of the sheet conveying belt surface, the sheet conveying belt surface The curvature of the printed paper can be changed and controlled. For this reason, when the adhesion of each sheet is high and it is difficult to separate each sheet, the curvature of the sheet adsorbed on the surface of the sheet conveying belt is increased so that the sheet and the sheet conveying belt are not directly adsorbed on the surface. The space formed between the next sheet and the next sheet can be increased to improve the separation of each sheet. On the contrary, when the adhesion of each sheet is low and each sheet is likely to vary, the curvature of the sheet adsorbed on the surface of the sheet conveying belt is decreased, and the space between this sheet and the next sheet is decreased. . Thereby, the respective sheets can be reliably separated and dispersed, and the double feeding of the sheets can be prevented.

In the paper feeding device of the present invention, the control unit controls the curvature of the surface of the paper transport belt according to at least one of the type of the paper, the moisture retention amount of the paper, and the charge amount of the paper. ing.

Depending on the type of paper, the thickness, rigidity, basis weight, etc. of the paper vary, and the adhesion of each paper changes, making it easier or less likely to cause double feeding of paper. Further, the adhesiveness of each sheet also changes depending on the moisture retention amount and the charge amount of the sheet, and the sheet multi-feeding is likely or difficult to occur. Therefore, the curvature of the surface of the paper transport belt is changed according to the type of paper, the moisture retention amount of the paper, and the charge amount, and the space formed between the paper adsorbed on the surface of the paper transport belt and the next paper is changed. Regardless of the change in the adhesion of each paper, the size is adjusted, and each paper is surely separated and dispersed to prevent double feeding of paper.

Furthermore, the paper feeding device of the present invention further includes an air suction unit that sucks air through a vent hole of the paper transport belt , and the control unit reduces the curvature of the surface of the paper transport belt as the thickness of the paper decreases. The amount of air sucked by the air suction unit is reduced to increase the amount.

The thinner the paper, the higher the adhesion between the papers, and the more likely the paper to be fed. Therefore, as the thickness of the sheet is reduced, by increasing the curvature of the sheet conveying belt surface, to increase the space between the the sheet and the next sheet adsorbed to the sheet conveying belt surface, the separation of each sheet It is increasing. Further, as the thickness of the sheet becomes thin, paper is easily attracted to the sheet conveying belt surface, thereby reducing the amount of suction air sucked through the ventilation holes of the sheet conveying belt.

Further, the sheet feeding apparatus of the present invention, the curvature setting change unit, by pressing the back surface of the sheet conveying belt, a pressing member for bending the surface of the paper conveying belt in a direction perpendicular to the conveying direction the control unit is configured to the pressing member is displaced to change the pressing amount for the rear surface of the paper conveying belt by the pressing member, which changes the curvature of the sheet conveying belt surface.

Thus changing the pressing amount for the rear surface of the sheet conveying belt by the pressing member, it is possible to change the curvature of the sheet conveying belt surface.

Further, the sheet feeding apparatus of the present invention, the pressing member presses the downstream portion of the back surface of the sheet conveying belt in a conveying direction of the sheet by the sheet conveying belt.

In the downstream part of the back side of the paper transport belt , the paper adsorbed on the surface of the paper transport belt is transported away from the next paper, so if each paper is dispersed well in this downstream part, each paper Can be effectively prevented.

For example, the paper feeding device according to the present invention includes a guide member that is in sliding contact with the back surface of the paper transport belt , and the pressing member presses the back surface of the paper transport belt through the opening of the guide member.

In the paper feeding device of the present invention, the pressing member is an eccentric cam, the back surface of the paper conveying belt is pressed by the peripheral surface of the eccentric cam, and the displacement of the peripheral surface of the eccentric cam causes the The amount of pressing against the back surface of the paper transport belt is changed.

In this case, by rotating the eccentric cam, it displaces the peripheral surface portion of the eccentric cam for pressing a back surface of the sheet conveying belt, to change the curvature of the sheet conveying belt surface.

Further, the sheet feeding apparatus of the present invention, the control unit controls the rotation angle of the eccentric cam to change the pressing amount for the rear surface of the paper conveying belt by the eccentric cam, the sheet conveying belt The curvature of the surface is adjusted.

When the eccentric cam is used as described above, the curvature of the surface of the sheet conveying belt can be adjusted by controlling the rotation angle of the eccentric cam.

In the paper feeding device according to the present invention, the plurality of paper transport belts are arranged in parallel in a direction orthogonal to the paper transport direction, and the back surfaces of the respective paper transport belts are respectively pressed by the plurality of pressing portions. Yes.

In this case, the curvature of the surface of the sheet conveying belt is changed for each sheet conveying belt . In addition, the paper adsorbed on each paper transport belt is curved at a plurality of locations in a direction orthogonal to the paper transport direction.

In the paper feeding device of the present invention, a suction path for air sucked through each of the paper transport belts 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.

  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, the adsorption of the surface of the sheet conveying belt on which is curved in the direction perpendicular to the conveying direction of the sheet can be controlled by changing the curvature of the sheet conveying belt surface, the sheet conveying belt surface The curvature of the printed paper can be changed and controlled. For this reason, when the adhesion of each sheet is high and it is difficult to separate each sheet, the curvature of the sheet adsorbed on the surface of the sheet conveying belt is increased so that the sheet and the sheet conveying belt are not directly adsorbed on the surface. The space formed between the next sheet and the next sheet can be increased to improve the separation of each sheet. On the contrary, when the adhesion of each sheet is low and each sheet is likely to vary, the curvature of the sheet adsorbed on the surface of the sheet conveying belt is decreased, and the space between this sheet and the next sheet is decreased. . Thereby, it is possible to reliably separate and disperse the respective sheets and to prevent the double feeding of the sheets.

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. FIG. 4 is a cross-sectional view showing the air intake duct and each paper transport belt as viewed from the side, with the recording paper being pulled out in the drawing direction. (A)-(d) is a figure which shows typically the relationship between the protrusion length of the surrounding surface of each eccentric cam, and the curvature of the surface of each paper conveyance belt. 3 is a block diagram illustrating a configuration of a control system of the image forming apparatus and the paper feeding apparatus. FIG. FIG. 3 is a cross-sectional view showing an uppermost recording sheet that is directly adsorbed and curved on the surface of each sheet conveying belt and a next recording sheet that is not directly adsorbed on the surface and is not curved.

  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 a first 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. 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 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.

  In addition, air suction ports 94 (shown in FIG. 8) that overlap with the plurality of air holes 81 a of the paper transport belt 81 are provided on the lower surface 85 g of the intake duct 85 for each paper transport belt 81. Each air suction hole 94 is connected to the air suction path of the intake duct 85.

  Furthermore, the front end portion 85c and the rear end portion 85d of the intake duct 85 are formed with respective recesses 85h, and the rollers 82 and 83 are disposed in these recesses 85h so as to be rotatably supported. The output shaft of the transport motor 93 is connected to the shaft of the front roller 82. Each paper transport belt 81 is bridged between the rollers 82 and 83.

  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 in by the intake / exhaust fan 84, and the air flows into the air suction ports 94 on the lower surface 85 g of the intake duct 85 and the air holes 81 a of the paper transport 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. 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 on both side end surfaces near the leading edge 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 the 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 so that the air enters between the recording sheets. Disperse the recording 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 intake / exhaust fan 84, and air is sucked through the air holes 81a of the paper transport belt 81 and the air suction ports 94 on the lower surface 85g of the air intake duct 85. The recording paper is sucked and adsorbed on the surface. At the same time, the rollers 82 and 83 are rotated by the transport motor 93 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. And the recording paper is conveyed through the conveyance path 33. Then, when the recording sheet is conveyed to the conveying roller pair 31, the suction of air by the intake / exhaust fan 84 and the rotation of the rollers 82 and 83 by the conveying motor 93 are temporarily stopped, and the recording sheet from the respective sheet conveying belts 81 is stopped. After the drawing 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 93 are resumed, and the next recording paper is sucked onto the surface of each paper transport belt 81, The recording paper is pulled out in the pulling-out direction E by the conveyance belt 81 and conveyed to the conveyance roller pair 31. Thereafter, the recording paper is repeatedly adsorbed on the surface of each paper conveyance belt 81, and the recording paper is collected by each paper conveyance belt 81. It is pulled out in the pulling direction E and conveyed.

  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 end face of the sheet bundle, thereby causing the recording sheets to vary. However, a plurality of recording sheets may still be pulled out on the surface of each sheet conveying belt 81, and if such a phenomenon is left unattended, recording sheets are double-fed.

  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 sheet adsorbed on the surface of each sheet conveying belt 81 is similarly curved, and the recording sheet that is directly adsorbed on the surface of each sheet conveying belt 81 and the curved recording sheet that is not directly adsorbed on the surface are next curved. A space is formed between the recording sheets and the recording sheets are separated. Thereby, double feeding of each recording sheet is prevented.

  Further, as the recording paper is thinner, the adhesion of each recording paper is higher, and the recording paper is more likely to be double fed.

  For this reason, in this embodiment, as the thickness of the recording sheet becomes thinner, the curvature of the surface of each sheet conveying belt 81 is increased, and the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet The space between the recording sheets is increased, the separation of each recording sheet is improved, each recording sheet is dispersed well, and double feeding of the recording sheets is prevented.

  Further, in the present embodiment, the amount of air sucked from each air hole 81a of each paper transport belt 81 is adjusted according to the thickness of the recording paper, and the surface of each paper transport belt 81 is controlled regardless of the thickness of the recording paper. The recording paper is adsorbed satisfactorily and curved. As a result, it is possible to reliably form a space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet, and to distribute each recording sheet satisfactorily.

  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 of the intake duct 85 and the respective sheet transport belts 81 taken along the same direction as FIG. 9 and viewed from the front. Further, FIG. 11 is a cross-sectional view showing the intake duct 85 and each paper transport belt 81 in a recording paper drawing direction E and viewed from the side.

  As shown in FIGS. 9 to 11, 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. The upper surface 85b of the top plate 101 and the lower surface 85g of the guide bottom plate 102 are substantially planar.

  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. The guide bottom plate 102 is formed with air suction ports 94 arranged in a direction orthogonal to the drawing direction E. The air suction ports 94 are located between the ribs 105a to 105e, and the paper transport belts 81 are provided. Thus, each air suction port 94 is covered.

  A bearing 107 projects from the outer side of the rib 105a of the guide bottom plate 102, and both ends of the rotary shaft 108 are rotatably supported by a shaft hole (not shown) formed in the bearing 107 and the partition wall 104. Has been. Four eccentric cams 114 are arranged and fixed on the rotary shaft 107 in a direction orthogonal to the drawing direction E, and each eccentric cam 114 is disposed at each air suction port 94 of the guide bottom plate 102. A drive gear 111 is fixed to one end of the rotating shaft 108 outside the partition wall 104, and a pinion gear 113 fixed to the output shaft of the cam motor 112 is engaged with the drive gear 111. When the cam motor 112 rotates, the pinion gear 113 and the drive gear 111 rotate, and the rotating shaft 108 and each eccentric cam 114 rotate.

  Along with the rotation of each eccentric cam 114, the protruding length m of the circumferential surface of each eccentric cam 114 from each air suction port 94 of the guide bottom plate 102 changes. Further, the rotation angle of the cam motor 112 and the protrusion length m of the peripheral surface of each eccentric cam 114 have a correspondence relationship. Therefore, by controlling the rotation angle of the cam motor 112, the protruding length m of the peripheral surface of each eccentric cam 114 can be changed. The protruding length m of the circumferential surface of each eccentric cam 114 is adjusted and set, for example, in the range of 0 mm to several mm.

  Further, since the diameter, the amount of eccentricity, and the direction of eccentricity of each eccentric cam 114 are set to be the same, the protruding length of the peripheral surface of each eccentric cam 114 regardless of the rotation angle of each eccentric cam 114. M always matches.

  Each sheet conveying belt 81 has elasticity, is stretched between the rollers 82 and 83, and contacts the planar lower surface 85 g of the intake duct 85 and the circumferential surface of each eccentric cam 114.

  Here, as shown in FIG. 12A, when the protruding length m of the circumferential surface of each eccentric cam 114 is 0 mm, the circumferential surface of each eccentric cam 114 is merely in contact with the back surface of each paper conveyance belt 81. Yes, the surface of each paper transport belt 81 is maintained flat. Also, as shown in FIGS. 12B, 12C, and 12D, when the protruding length m of the peripheral surface of each eccentric cam 114 is longer than 0 mm, the peripheral surface of each eccentric cam 114 is each sheet. By pressing the back surface of the conveyance belt 81, the surface of each paper conveyance belt 81 is curved in a direction orthogonal to the drawing direction E, and each paper conveyance belt 81 is corresponding to the protruding length m of the circumferential surface of each eccentric cam 114. The curvature of the surface changes. Of course, the curvature of the surface of each paper conveying belt 81 increases as the protruding length m of the circumferential surface of each eccentric cam 114 increases.

  Therefore, by controlling the rotation angle of the cam motor 112 and changing the protruding length m of the circumferential surface of each eccentric cam 114, the surface of each paper transport belt 81 can be made flat or the surface of each paper transport belt 81 can be changed. The curvature of the surface can be adjusted and controlled.

  In a state where the surface of each paper transport belt 81 is flat, the recording paper adsorbed on the surface of each paper transport belt 81 is flat. Further, in a state where the surface of each paper transport belt 81 is curved, the recording paper adsorbed on the surface of each paper transport belt 81 is curved (waved), and the curvature of the surface of each paper transport belt 81 and the curvature of the recording paper are recorded. Are almost the same.

  Further, as shown in FIG. 11, each eccentric cam 114 presses a downstream portion of the back surface of each paper transport belt 81 in the drawing direction E. Therefore, each eccentric cam 114 curves the downstream portion of the surface of each paper transport belt 81.

  Next, the configuration of the control system of the image forming apparatus 1 and the paper feeding device 71 will be described. FIG. 13 is a block diagram showing the configuration of the control system. In FIG. 13, the control unit 121 integrally controls the image forming apparatus 1, the sheet feeding device 71, and the like, and includes a CPU, a RAM, a ROM, various interfaces, and the like. The input operation unit 122 includes, for example, a plurality of operation keys, a liquid crystal display device, and a touch panel superimposed on the screen of the liquid crystal display device, and displays operation guidance and the like of the image forming apparatus 1 on the screen of the liquid crystal display device. Data or the like input by an operation of each operation key or the like is output to the control unit 121. The memory 123 is a hard disk device (HDD), for example, and stores various data and programs. The image processing unit 124 performs various types of image processing on the image data.

  In such a configuration, for example, the control unit 121 causes the document reading device 2 to read an image on a document sheet, stores image data indicating the image on the document sheet in the memory 123, and the image processing unit 124 stores the image data in the memory 123. The image data is processed, and the printing unit 11 records the image of the original paper indicated by the image data in the memory 123 on the recording paper.

  Further, when the paper supply unit 13 is selected and instructed by the operation of the input operation unit 122, the control unit 121 controls the paper supply unit 13 in response to this and records from the paper supply unit 13 to the printing unit 11. A sheet is fed, and an image of a document is recorded on the recording sheet.

  Alternatively, when the large capacity sheet cassette 14 is selected and instructed by the operation of the input operation unit 122, the control unit 121 controls each motor, fan, and the like in the sheet feeding device 71 of the large capacity sheet cassette 14 to supply the sheet. A recording sheet is fed from the paper device 71 to the printing unit 11, and an image of a document is recorded on the recording sheet.

  Furthermore, the thickness of the recording paper stored in the large-capacity paper feed cassette 14 can be input by operating the input operation unit 122, and the thickness of the recording paper can be stored in the memory 123. For example, “thin paper”, “plain paper”, and “thick paper” are displayed on the screen of the input operation unit 122, and any of “thin paper”, “plain paper”, and “thick paper” is displayed by the operation of the input operation unit 122. Select and store in memory 123. The thickness of one of the “thin paper”, “plain paper”, and “thick paper”, that is, the thickness of the recording paper is controlled by adjusting the curvature of the surface of each paper transport belt 81 and the thickness of each paper transport belt 81 as described later. It is used for adjusting and controlling the air suction amount from each vent hole 81a.

  Next, the paper feeding operation of the paper feeding device 71 will be described in detail. First, as shown in FIG. 8, the sheet bundle is placed on the sheet stacking table 74, and the sheet bundle is positioned between the column portion 76 a of the sheet rear end guide 76 and the contact plate 72 b of the outer frame body 72, The sheet bundle is positioned between the assist ducts 77 and 78.

  When storing the sheet bundle, the user operates the input operation unit 122 in FIG. 13 to determine the thickness of the recording sheet (“thin paper”, “plain paper”, and "Thick paper") is input, and the thickness of the recording paper is stored in the memory 123.

  The control unit 121 reads the thickness of the recording sheet from the memory 123, drives the cam motor 112 to rotate, controls the rotation angle of the cam motor 112, and changes the protrusion length m of the circumferential surface of each eccentric cam 114. The curvature of the surface of each paper transport belt 81 is adjusted and controlled.

  Here, when “thin paper” is stored in the memory 123 as the thickness of the recording paper stored in the large-capacity paper feed cassette 14, the protrusion length m of the circumferential surface of each eccentric cam 114 is set to the longest. The length mx is set, and the curvature of the surface of each paper conveying belt 81 is increased (state shown in FIG. 12D). When “plain paper” is stored in the memory 123 as the thickness of the recording paper, the protruding length m of the peripheral surface of each eccentric cam 114 is set to a medium length mm, and each paper is The curvature of the surface of the conveyor belt 81 is set to a medium level (state shown in FIG. 12C). Further, when “thick paper” is stored in the memory 123 as the thickness of the recording paper, the protruding length m of the circumferential surface of each eccentric cam 114 is set to the shortest length ms, and each paper conveying belt is set. The curvature of the surface of 81 is made small (state of FIG.12 (b)). Note that 0 mm <length ms <length mm <length mx.

  After the curvature of the surface of each paper transport belt 81 is adjusted and set according to the thickness of the recording paper stored in the large-capacity paper feed cassette 14 in this way, the control unit 121 controls the pulse motor 92 of the paper feed device 71. , And the winding pulleys 98 are rotated clockwise by the pulse motor 92 to raise the paper stacking table 74 and position the recording paper on the top layer of the paper bundle at a predetermined height. For example, the pulse motor 92 is rotationally driven until the uppermost recording sheet of the sheet bundle is detected by a sensor (not shown) provided on the head 76b of the sheet rear end guide 76, and the sheet stacking board 74 is moved. Raise.

  Further, the control unit 121 rotationally drives the assist fans 79 and 80 of the sheet feeding device 71 to send air from the assist fans 79 and 80 to the assist ducts 77 and 78. The air outlets 77a and 78a are blown to both end surfaces near the leading end of the sheet bundle on the sheet stacking base 74, so that air enters between the recording sheets and the recording sheets are dispersed.

  Further, the control unit 121 rotates and drives the intake / exhaust fan 84 of the sheet feeding device 71 to send air from the intake / exhaust fan 84 to the exhaust duct 86, and the air is discharged from each exhaust hole 86 b of the exhaust duct 86. The air is blown onto the front end surface to allow air to enter between the recording sheets, and the recording sheets are dispersed. Then, air is sucked from the air intake duct 85 to the air intake / exhaust fan 84, and each of the rollers 82, 83 is sucked through the air suction ports 94 on the air holes 81a of the paper conveying belt 81 and the lower surface 85g of the air intake duct 85. , The paper transport belts 81 are moved around, the recording paper is adsorbed on the surface of the paper transport belts 81, and the recording paper is pulled out in the drawing direction E by the paper transport belts 81 and transported.

  At this time, the control unit 121 controls the rotational speed of the intake / exhaust fan 84 according to the thickness of the recording paper, and adjusts and sets the air suction amount (and exhaust amount) by the intake / exhaust fan 84. For example, when “thin paper” is stored in the memory 123 as the thickness of the recording paper, the air suction amount by the intake / exhaust fan 84 is set to be small. Thin paper is light and flexible. For this reason, even if the suction amount of air from each air hole 81a of each paper transport belt 81 is set to be small, the recording paper is satisfactorily attracted to the surface of each paper transport belt 81, and the recording paper is fed to each paper transport belt. It can be sufficiently curved along the surface of 81.

  When the recording paper is “thin paper”, the protrusion length m of the circumferential surface of each eccentric cam 114 is set to the longest length mx, and the curvature of the surface of each paper conveyance belt 81 is increased. Therefore (the state of FIG. 12D), the space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet becomes large. For this reason, even if the recording paper is “thin paper” and the adhesiveness of each recording paper is high, each recording paper is well separated and varies.

  When “plain paper” is stored in the memory 123 as the thickness of the recording paper, the air suction amount by the intake / exhaust fan 84 is set to a medium level. Plain recording paper is moderate in weight and rigidity. For this reason, the recording paper is attracted to the surface of each paper transport belt 81 and curved by setting the air suction amount from each air hole 81 a of each paper transport belt 81 to a medium level.

  When the recording paper is “plain paper”, the protruding length m of the circumferential surface of each eccentric cam 114 is set to a medium length mm, and the curvature of the surface of each paper conveying belt 81 is set to the medium. Therefore, the space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet becomes medium, and each recording sheet Good separation and variation.

  Further, when “thick paper” is stored in the memory 123 as the thickness of the recording paper, the air suction amount by the intake / exhaust fan 84 is set large. Thick paper is heavy and has high rigidity. For this reason, it is necessary to ensure that the recording sheet is sucked and curved on the surface of each sheet conveying belt 81 by setting a large amount of air sucked from each vent hole 81 a of each sheet conveying belt 81.

  When the recording paper is “thick paper”, the protrusion length m of the circumferential surface of each eccentric cam 114 is set to the shortest length ms, and the curvature of the surface of each paper transport belt 81 is reduced. (The state shown in FIG. 12B), the space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet is reduced, but the recording sheet is “thick paper”. Since the adhesion of each recording paper is low, each recording paper is well separated and varies.

  FIG. 14 is a cross-sectional view showing a space between a recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet. As shown in FIG. 14, even if a plurality of recording papers Pa1 and Pa22 are pulled up while overlapping on the surface of each paper transport belt 81, the uppermost recording paper that is directly attracted to the surface of each paper transport belt 81 and curved. A space is formed between Pa1 and the next flat recording paper Pa2 that is not directly attracted to the surface, and the recording papers Pa1 and Pa2 are separated.

  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 between the recording papers Pa1 and Pa2, and the recording paper Pa2 is surely discharged from the recording paper Pa1. To separate. This effectively prevents double feeding of the recording papers Pa1 and Pa2.

  In addition, the uppermost recording paper Pa1 is curved at four locations along the curved surface of each paper conveying belt 81, and four spaces are formed between the recording paper Pa1 and the next recording paper Pa2. Double feeding of the papers Pa1 and Pa2 is reliably prevented. Even if the size of the recording papers Pa1 and Pa2 is small, the recording paper Pa1 is curved along at least one curved surface, and a space between the recording paper Pa1 and the next recording paper Pa2 is reliably formed. Therefore, double feeding of the recording papers Pa1 and Pa2 is prevented.

  Further, since the recording paper adsorbed on the surface of each paper transport belt 81 is transported away from the next recording paper at the downstream side portion of the surface of each paper transport belt 81, each deviation as shown in FIG. The downstream portion of the surface of each paper conveying belt 81 is curved by the core cam 114, and each recording paper is favorably dispersed at this downstream portion, thereby effectively preventing double feeding of the recording paper. .

  As described above, in the paper feeding device 71 of the present embodiment, the curvature of the surface of each paper conveying belt 81 is changed according to the thickness of the recording paper, and the air suction amount by the intake / exhaust fan 84 is changed according to the thickness of the recording paper. Therefore, regardless of the thickness of the recording paper, the recording paper is satisfactorily attracted to the surface of each paper conveying belt 81, and the recording paper is bent appropriately, and this recording paper and the next recording paper By forming a space between the recording sheets, the recording sheets can be dispersed well, and the multiple feeding of the recording sheets can be prevented.

  In the above embodiment, the curvature of the surface of each paper transport belt 81 and the amount of air sucked by the intake / exhaust fan 84 are changed according to the thickness of the recording paper, but according to the rigidity and basis weight of the recording paper. Even if the curvature of the surface of each paper conveying belt 81 or the amount of air sucked by the intake / exhaust fan 84 is changed, the same effect can be obtained. This is because the thickness, rigidity, and basis weight of the recording paper have a corresponding relationship. For example, as the recording paper becomes thinner, the rigidity and basis weight tend to decrease, and as the recording paper becomes thicker, the rigidity and basis weight tend to increase.

  Further, although “thin paper”, “plain paper”, and “thick paper” are illustrated as the thickness of the recording paper, the thickness of the recording paper may be classified into two types or four or more types. . Also, once “Thin paper”, “Plain paper”, and “Thick paper” are set, the thickness can be finely adjusted manually, and the curvature of the surface of each paper transport belt 81 is finely adjusted accordingly. You can adjust it.

  Alternatively, the moisture retention amount of the recording sheet may be detected by a sensor, and the curvature of the surface of each sheet conveyance belt 81 may be changed according to the moisture retention amount. This is because when the moisture retention amount of the recording paper is increased, the recording paper is likely to bend like a thin paper and the adhesion of each recording paper is increased. It is necessary to increase the space between each recording sheet and increase the separation of each recording sheet. When the moisture content of the recording sheet decreases, the recording sheet becomes difficult to bend like a thick sheet. This is because each recording sheet is separated without increasing the space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet.

  Furthermore, the charge amount of the recording paper (static charge amount) may be detected by a sensor, and the curvature of the surface of each paper transport belt 81 may be changed according to the charge amount. This is because if the charge amount of the recording sheet is large, the adhesion of each recording sheet is increased, so that it is necessary to increase the space between the recording sheet adsorbed on the surface of each sheet conveying belt 81 and the next recording sheet. In addition, if the charge amount of the recording sheet is small, the adhesiveness of each recording sheet is lowered, so there is no need to increase the space between this recording sheet and the next recording sheet.

  Further, regardless of the rotation angle of each eccentric cam 114, the protrusion length m of the peripheral surface of each eccentric cam 114 is always matched, and the curvature of the surface of each paper transport belt 81 is always matched. The curvature of the surface of each paper conveying belt 81 may be adjusted separately by changing the shape of each eccentric cam 114 or shifting the phase of each eccentric cam 114.

  Further, the back surface of each paper transport belt 81 is pressed by each eccentric cam 114 and the surface of each paper transport belt 81 is curved, but the back surface of each paper transport belt 81 is pressed by another pressing member. It doesn't matter. For example, the back surface of the paper transport belt 81 can be pressed using a screw screw or the like. Furthermore, the eccentric cam or the pressing member may be displaced by manual control (operation) according to the thickness of the recording paper.

  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 stack 75 Paper drawer part 76 Paper rear end guides 77, 78 Assist ducts 79, 80 Assist fan 81 Paper transport belts 82, 83 Rollers 84 Air intake / exhaust fan 85 Air intake duct 86 Exhaust Duct 92 Pulse motor 93 Conveyance motor 94 Air suction port 112 Cam motor 114 Eccentric cam (pressing member)
121 Control Unit 122 Input Operation Unit 123 Memory 124 Image Processing Unit

Claims (11)

A paper feeding device that sucks air through a vent hole of a paper transport belt to attract and transport the paper to the surface of the paper transport belt ;
And said surface of the sheet conveying belt is curved in the direction perpendicular to the conveying direction of the sheet, the curvature setting changing unit for changing a curvature of the sheet conveying belt surface,
A control unit for controlling the curvature setting changing unit;
A guide portion for guiding the paper conveying belt ,
The guide portion includes a sheet feeding apparatus which comprises said extending in the conveying direction and adjacent to the side edge of the sheet conveying belt, projecting from the surface of the guide portion on the side of the sheet conveying belt ribs . The sheet feeding device according to claim 1,
The control unit controls the curvature setting changing unit that changes the curvature of the surface of the sheet conveying belt in accordance with at least one of the type of sheet, the moisture retention amount of the sheet, and the charge amount of the sheet. A paper feeder. The sheet feeding device according to claim 1 or 2,
An air suction part for sucking air through the vents of the paper transport belt ;
The sheet feeding device , wherein the control unit increases the curvature of the surface of the sheet conveying belt as the sheet becomes thinner, and reduces the amount of air sucked by the air sucking unit. The sheet feeding device according to any one of claims 1 to 3,
The curvature setting change unit, by pressing the back surface of the sheet conveying belt, a pressing member for bending the surface of the paper conveying belt in a direction perpendicular to the conveying direction,
The control unit, said pressing member is displaced, the sheet feeding apparatus to change the pressing amount for the rear surface of the paper conveying belt by the pressing member, and changing a curvature of the sheet conveying belt surface. The sheet feeding device according to claim 4,
The paper feeding device , wherein the pressing member presses a downstream portion of a back surface of the paper transport belt in a paper transport direction by the paper transport belt . The sheet feeding device according to claim 4 or 5,
A guide member that is in sliding contact with the back surface of the paper transport belt ;
The paper feeding device, wherein the pressing member presses a back surface of the paper conveying belt through an opening of the guide member. The sheet feeding device according to any one of claims 4 to 6,
The pressing member is an eccentric cam, the back surface of the paper transport belt is pressed by the peripheral surface of the eccentric cam, and the amount of press against the back surface of the paper transport belt is changed by the displacement of the peripheral surface of the eccentric cam. A paper feeder characterized by that. The sheet feeding device according to claim 7,
Wherein the control unit controls the rotation angle of the eccentric cam to change the pressing amount for the rear surface of the paper conveying belt by the eccentric cam, and adjusting the curvature of the sheet conveying belt surface Paper feeder. The sheet feeding device according to any one of claims 4 to 8,
A plurality of the paper transport belts are juxtaposed in a direction perpendicular to the paper transport direction,
A paper feeding device that presses the back surface of each paper transport belt by the plurality of pressing portions. The sheet feeding device according to claim 9,
A sheet feeding device , wherein a suction path for air sucked through each of the sheet conveying belts is provided in a direction orthogonal to the sheet conveying direction.   An image forming apparatus comprising the paper feeding device according to claim 1.

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