JP2016130176A - Paper feeder and image forming apparatus comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder which has a simple structure and can effectively suck and pull out a sheet regardless of the size of the sheet, and to provide an image forming apparatus comprising the same.SOLUTION: A paper feeder stacks a sheet bundle on a sheet stacker, sucks a sheet in the sheet bundle to a sheet conveyance member by sucking air with a suction duct, and conveys it. The suction duct has first air suction ports formed in a center section in a direction perpendicular to the conveyance direction of the sheet and second air suction ports which are smaller than the first air suction ports formed in side sections in such a manner that a plurality of them are arranged along the conveyance direction of the sheet.SELECTED DRAWING: Figure 11

Description

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

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

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

  For example, in Patent Document 1, air is blown from the floating nozzles of the air duct to the front end surface of the sheet bundle, the sheets of the sheet bundle are dispersed and floated, and the uppermost sheet of the sheet bundle is conveyed by the sheet conveyance belt. Is sucked and transported. In addition, a shutter that changes the opening area of each floating nozzle or the opening area of the air escape hole of the air duct is provided, and the amount of air blown from each floating nozzle by the shutter is adjusted to be either thin paper or thick paper The sheets in the bundle are floated appropriately.

Japanese Patent Laid-Open No. 2001-3272

  By the way, in many cases, the width of the suction region by the paper transport belt is adjusted to the width of the medium or small size paper. This is because, when the width of the suction area by the paper transport belt is matched to the large paper width, when the medium or small size paper is sucked by the paper transport belt, A large amount of air is sucked from the open vent hole, reducing the amount of air sucked from the vent hole of the paper transport belt that is adsorbing the paper, and adsorbing the paper by the paper transport belt. This is because the force is reduced and adsorption failure occurs.

  For this reason, based on the configuration for adjusting the air blowing amount from each floating nozzle of the air duct described in Patent Document 1, the air from the vent hole of the paper transport belt when adsorbing the medium size or small size paper A configuration in which the suction amount is increased to maintain the suction force is conceivable.

  However, in order to change the amount of air sucked from the vent of the paper transport belt, it is necessary to provide a shutter in the vent or to control the motor of the fan that sucks air, increasing the number of parts and costs, The complexity of the configuration cannot be avoided.

  Therefore, the present invention has been made in view of the above-described conventional problems, and has a simple configuration, and a paper feeding device capable of adsorbing and drawing out paper regardless of the paper size and the same An object is to provide an image forming apparatus provided.

In order to solve the above-described problems , the present invention provides the following sheet feeding device and image forming apparatus.

(1) Paper feeder
A sheet feeding device according to the present invention is a sheet feeding device that stacks a sheet bundle on a sheet stacking table, sucks air by a suction duct, and sucks and conveys sheets of the sheet bundle to a sheet conveying member, The suction duct has a first air suction port formed at the center side in a direction orthogonal to the paper transport direction, and a second air suction port smaller than the first air suction port at both ends. Are formed along the sheet conveyance direction.

(2) Image forming apparatus
An image forming apparatus according to the present invention includes the sheet feeding device according to the present invention.

In the present invention, the suction duct can be exemplified by a suction auxiliary hole formed between the first air suction port and the second air suction port.

In the present invention, a plurality of the first air suction ports can be exemplified along a direction orthogonal to the transport direction of the paper.

In the present invention, the suction duct can be exemplified by a mode in which suction auxiliary holes are formed between the plurality of first air suction ports along the direction orthogonal to the sheet conveyance direction on the center side.

In the present invention, it is possible to exemplify an embodiment in which the sheet conveying member is a sheet conveying belt provided with a plurality of air holes.

In the present invention, the suction duct can be exemplified by an aspect in which the first air suction port and the second air suction port are formed at positions where they overlap the paper transport member.

In the present invention, the suction duct is formed such that the first air suction port is formed at a position overlapping the paper transport member, and the first air suction port and the second air suction port are located between the first air suction port and the second air suction port. A mode in which the suction auxiliary hole is formed at a position overlapping with the sheet conveying member can be exemplified.

In the present invention, the sheet conveying member is a plurality of sheet conveying belts each having a plurality of air holes, and the suction duct is provided in the first air provided at a position overlapping with the plurality of sheet conveying belts. A suction port and a second air suction port; and a suction auxiliary hole provided at a position between adjacent paper transport belts among the plurality of paper transport belts, A suction region provided by the suction auxiliary hole provided at a position between adjacent paper transport belts and sucking air is smaller on the end side than the center side of the paper transport member in a direction orthogonal to the paper transport direction. Examples of such distributed modes can be illustrated.

In the present invention, the overall shape of the first air suction port and the second air suction port is substantially rectangular, and the area of the second air suction port is larger than the area of the first air suction port. A mode that is reduced can be exemplified.

In the present invention, the overall shape of the first air suction port and the second air suction port is substantially diamond-shaped, and the area of the second air suction port is larger than the area of the first air suction port. A mode that is reduced can be exemplified.

In the present invention, the overall shape of the first air suction port and the second air suction port is a substantially isosceles triangle shape, and the area of the second air suction port is the area of the first air suction port. The aspect made smaller than this can be illustrated.

In such a present invention, the suction duct has a first air suction port formed at the center side in a direction orthogonal to the sheet conveyance direction, and a second smaller than the first air suction port at both ends. Since multiple air suction ports are formed along the paper transport direction, the area of the effective suction area that is open simultaneously on both outer sides of the paper is reduced when suctioning small paper. The amount of air sucked from the effective suction area is suppressed, and the amount of air sucked from the effective suction area that actually sucks the paper is not insufficient, so that the paper can be satisfactorily sucked.

1 is a cross-sectional view illustrating an image forming apparatus to which an embodiment of a paper feeding device of the present invention is applied. It is a top view which shows the paper feeder of this embodiment. It is a front view which shows a paper feeder. FIG. 3 is a perspective view showing the sheet feeding device with the sheet drawer portion removed, as viewed obliquely from the rear. FIG. 6 is a perspective view showing a paper drawer portion when viewed obliquely from the upper front. It is a perspective view which shows a paper drawer part seeing from diagonally upper back. It is a perspective view which shows a paper drawer part seeing from diagonally lower back. FIG. 3 is a perspective view showing the suction duct and each paper transport belt of the paper feeder broken in a direction perpendicular to the recording paper drawing direction. FIG. 6 is a cross-sectional view illustrating a state of two recording sheets adsorbed by each sheet conveying belt. It is sectional drawing which shows a paper feeding apparatus roughly. It is a top view which shows each paper conveyance belt, the baseplate of a suction duct, each roller, etc. seeing from the downward direction. FIG. 6 is a plan view showing a state in which a standard postcard size recording sheet is adsorbed as viewed from below. FIG. 6 is a plan view showing a state in which a recording paper P having a standard B5 size is adsorbed as viewed from below. (A), (b) is a top view which shows the modification of the air suction opening formed in the baseplate of a suction duct seeing from the downward 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 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.

  Further, 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 the reading position below the original reading glass 55, and the first scanning unit 45 is moved in accordance with the position of the first scanning unit 45. The two scanning unit 46 is positioned. 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.

  Further, a second reading unit 43 (contact image sensor (CIS)) built in the document conveying unit 42 passes under the second reading unit (CIS) 43 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 paper transport 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 unit 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, a suction 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 into the intake / exhaust fan 84 through the suction duct 85. Further, the air exhausted from the intake / exhaust fan 84 is guided through the exhaust duct 86 and is blown out from the exhaust duct 86 to the inside of the outer frame body 72 in the direction opposite to the extraction direction E (rearward).

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

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

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

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

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

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

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

  The suction duct 85 is a hollow body and has an air suction path that is long in a direction orthogonal to the drawing direction (paper transport direction) E, and one end 85 a of the suction duct 85 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 suction duct 85 to the intake port (not shown) of the intake / exhaust fan 84 through the one side end portion 85a.

  Also, the front end portion 85c and the rear end portion 85d of the suction 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 97 is connected to the shaft of the front roller 82. Each paper transport belt 81 is stretched between the rollers 82 and 83 and contacts the upper plate 85b and the bottom plate 85g of the suction duct 85.

  Here, the front roller 82 is rotationally driven in the arrow direction D by the transport motor 97, the rear roller 83 is driven to rotate, and each paper transport belt 81 rotates in the arrow direction D. In addition, air in the suction duct 85 is sucked by the intake / exhaust fan 84, and air flows through the air suction ports 103a and 103b (shown in FIG. 8) of the bottom plate 85g of the suction duct 85 and the air holes 81a of the paper transport belt 81. Then, the uppermost recording sheet of the sheet bundle on the sheet stacking table 74 is attracted to the surface of each sheet conveying belt 81, and the recording sheet is pulled out and conveyed by each sheet conveying belt 81.

  As shown in the cutaway perspective view of FIG. 8, five ribs 101a to 101e extending in the drawing direction E are formed on the bottom plate 85g of the suction duct 85, and each sheet conveying belt 81 is disposed between the ribs 101a to 101e. Has been. In addition, between the ribs 101a to 101e, the bottom surface of the bottom plate 85g of the suction duct 85 is a smooth curved surface 102a to 102d that protrudes downward, and the paper transport belt 81 is formed on the curved surfaces 102a to 102d. The surface of each paper transport belt 81 is curved along the curved surfaces 102a to 102d. Further, air suction ports 103a and 103b are formed on the curved surfaces 102a to 102d so as to overlap with the plurality of air holes 81a of the paper transport belt 81, and the air suction ports 103a and 103b are covered by the paper transport belt 81. ing. In addition, small suction assist holes 104, 107a, 107b are also formed in the curved surfaces 102b, 102c and the ribs 101c-101d.

  As shown in FIG. 9, when air is sucked through the air holes 81 a of the paper conveyance belt 81, the air suction ports 103 a and 103 b of the suction duct 85, and the suction auxiliary holes 104, 107 a and 107 b, The recording paper Pa1 is adsorbed on the surface. Then, a space is formed between the uppermost recording paper Pa1 that is directly attracted to the surface of each paper transport belt 81 and curved and the next recording paper Pa2 that is not directly attracted to the surface and is not curved, and each recording paper Pa1. The air reliably enters between Pa2 and Pa2, and the recording papers Pa1 and Pa2 are easily separated.

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

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

  One end 85a of the suction duct 85 and one end 86a of the exhaust duct 86 are connected to the intake / exhaust fan 84, and the other end 85f of the suction 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 suction duct 85, and the exhaust duct 86 are integrated.

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

  In this state, air is sucked from the suction duct 85 to the suction / exhaust fan 84, and the air is passed through the air holes 81a of the paper transport belt 81, the air suction ports 103a and 103b of the suction duct 85, and the suction auxiliary holes 104, The recording paper is sucked through 107a and 107b, and the recording paper is sucked and sucked onto the surface of each paper transport belt 81. At this time, a space is formed between the uppermost recording paper that is directly adsorbed and curved on the surface of each paper conveying belt 81 and the next recording paper that is not directly adsorbed on the surface and is not curved, and between the recording papers. Air will surely enter. As a result, the adhesion of each recording sheet in the sheet bundle is reduced, and the recording sheet can be easily pulled out from the sheet bundle, and the recording sheets can be pulled out one by one.

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

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

  By the way, as shown in FIG. 9, the distance between the outer ends of the inner two sheet conveying belts 81 is slightly narrower than the lateral width of the standard postcard size, and the distance between the outer ends of the two outer sheet conveying belts 81 is It is slightly wider than the width of the standard B5 size. Further, the width of the conveyance path of the recording paper conveyed by the four paper conveyance belts 81 is slightly longer than the horizontal width of the standard A3 size, and the maximum size of the recording paper that can be conveyed is the standard A3 size.

  Accordingly, when the recording paper P is a standard postcard size, the entire recording paper P is adsorbed by the two inner paper conveyance belts 81. Further, when the recording paper P is a standard B5 size, the entire recording paper P is adsorbed by the four paper transport belts 81. Further, when the recording paper P is larger than the standard B5 size, the central portion of the recording paper P is adsorbed by the four paper transport belts 81.

  Here, when the recording paper P is larger than the standard B5 size, the recording paper P overlaps all the air holes 81a of the four paper conveying belts 81 to which air is sucked at the same time. Since the air holes 81a are blocked, the recording paper P is favorably adsorbed by the four paper transport belts 81.

  However, when the recording paper P is approximately a postcard size, the recording paper P overlaps with the air holes 81a of the two inner paper transport belts 81 where air is sucked at the same time. Even if the recording paper P is adsorbed, the recording paper P does not overlap the vent holes 81a of the two outer paper transport belts 81 where air is sucked at the same time. The pores 81a are opened.

  If a large amount of air is sucked from the open vent holes 81a of the two outer paper transport belts 81, the air holes 81a of the two inner paper transport belts 81 adsorbing the recording paper P are sucked. The suction amount of the air is insufficient, the suction power of the recording paper P by the two inner paper transport belts 81 is reduced, and suction failure occurs.

  Therefore, in the paper feeding device 71 of the present embodiment, the size of the air suction ports 103a and 103b and the like formed in the bottom plate 85g of the suction duct 85 is changed for each of the four paper transport belts 81, and the air suction ports 103a and 103a are changed. The number of the air holes 81a of the paper conveying belt 81 that overlaps with 103b or the like is changed, and the number of the air holes 81a of the two outer paper conveying belts 81 where the air is simultaneously sucked is changed to the two inner holes where the air is simultaneously sucked. The number of the air holes 81a of the paper conveying belt 81 is smaller than the number of the air holes 81a.

  As a result, even if the recording paper P is approximately a postcard size and the air holes 81a of the two outer paper transport belts 81 from which air is sucked simultaneously are opened, the air holes 81a are opened. The suction amount of air is suppressed, the suction amount of air from the air holes 81a of the two inner paper transport belts 81 adsorbing the recording paper P is not short, and the two inner paper transport belts 81 The recording paper P is adsorbed satisfactorily.

  Next, the sizes of the air suction ports 103a and 103b formed in the bottom plate 85g of the suction duct 85 will be described in detail.

  FIG. 11 is a plan view showing each paper transport belt 81, the bottom plate 85g of the suction duct 85, each of the rollers 82, 83, and the like when viewed from below. As shown in FIGS. 9 and 11, each sheet conveying belt 81 is disposed between each rib 101 a to 101 e formed on the bottom plate 85 g of the suction duct 85, and each curve of the bottom plate 85 g slidably contacting each sheet conveying belt 81. A large air suction port 103a or a small air suction port 103b is formed on the surfaces 102a to 102d.

  A large air suction port 103a is formed on each of the curved surfaces 102b and 102c overlapping the two sheet conveying belts 81 on the center side in a direction orthogonal to the drawing direction E, and four suction auxiliary holes 104 are formed. The slits 105 are formed side by side in the drawing direction E, and four slits 105 are formed in the drawing direction E.

  Further, small air suction ports 103b are formed side by side in the drawing direction E on each of the curved surfaces 102a and 102d that overlap the two outer paper conveyance belts 81 in the direction orthogonal to the drawing direction E. Each small-sized air suction port 103b has a bridge portion 103c that divides the air suction port 103b across the air suction port 103b in a direction orthogonal to the drawing direction E.

  Further, suction assist holes 107 a and 107 b are also formed in the ribs 101 b to 101 d between the paper transport belts 81. The suction auxiliary holes 107b of the ribs 101b and 101d have respective bridge portions 107c that are divided across the suction auxiliary holes 107b in a direction orthogonal to the drawing direction E.

  The bridge portions 103c and 107c are provided to prevent the sheet conveying belt 81 from being sucked into the air suction port 103b and the suction auxiliary hole 107b and prevent the surface of the sheet conveying belt 81 from being deformed into a concave shape. Yes.

  Here, in each of the curved surfaces 102b and 102c on the center side, 15 air holes 81a overlap with the large-sized air suction port 103a, and 4 air holes 81a overlap with each suction auxiliary hole 104, for a total of 19 Air is simultaneously sucked from the air holes 81a. In each of the curved surfaces 102a and 102d on both end sides, 16 air holes 81a are overlapped with each small-sized air suction port 103b, and air is simultaneously sucked from a total of 16 air holes 81a. Furthermore, the suction auxiliary hole 107a of the rib 101c has a larger opening area than the suction auxiliary hole 107b of the ribs 101b and 101d.

  Accordingly, the area of the suction duct 85 where air on the outer peripheral side of each paper transport belt 81 is sucked simultaneously is defined as the effective suction area, that is, each air hole 81a and each rib 101b of each paper transport belt 81 where air is sucked simultaneously. Assuming that each of the suction auxiliary holes 107a and 107b of ˜101d is an effective suction area, the effective suction area is distributed so as to be smaller at both ends than the center side of each paper transport belt 81 in the direction orthogonal to the drawing direction E. It can be said that the ratio of the area of the effective suction area to the unit area of the surface of each paper transport belt 81 facing the recording paper is smaller at both ends than at the center. Further, the air holes 81a through which air is sucked simultaneously and the suction auxiliary holes 107a and 107b are arranged symmetrically with respect to the center of the recording paper sucked by the paper transport belts 81, and the effective suction area is also recorded. They are arranged symmetrically with respect to the center of the paper.

For this reason, for example, as shown in FIG. 12, when the recording paper P having a standard postcard size is adsorbed by the two inner paper conveyance belts 81, the air suction of the curved surfaces 102 b and 102 c on the center side is performed by the recording paper P A total of 19 ventilation holes 81a overlapping the opening 103a and each suction auxiliary hole 104, the suction auxiliary holes 107a of the rib 101c, and half of the suction auxiliary holes 107b of the ribs 101b and 101d are blocked, and A total of 16 vent holes 81a overlapping the air suction ports 103b of the curved surfaces 102a and 102d and half of the suction auxiliary holes 107b of the ribs 101b and 101d are simultaneously opened, and the recording paper P is actually sucked. vent hole 81a and the suction auxiliary hole 107a of each rib 101C～101d, than the total area of 107 b, the vent holes 81a and the ribs 101b that is opened at the same time Towards the total area of the suction auxiliary holes 107b of 101d decreases. As a result, the air suction amount from the suction auxiliary holes 107b of the air holes 81a and the ribs 101b and 101d that are opened simultaneously is suppressed, and the air holes 81a and the ribs that actually adsorb the recording paper P are suppressed. The amount of air sucked from the suction auxiliary holes 107a and 107b of 101c to 101d does not become insufficient, and the recording paper P is favorably adsorbed by the two inner paper conveyance belts 81.

For example, as shown in FIG. 13, when a standard A5 size recording sheet P is adsorbed to four sheet conveying belts 81, the recording sheet P causes the air suction ports 103 a of the curved surfaces 102 b and 102 c on the center side to be sucked. In addition, a total of 19 ventilation holes 81a that overlap with the suction auxiliary holes 104, a suction auxiliary holes 107a and 107b of the ribs 101b to 10d, and a total of 16 air holes 103b that overlap the curved surfaces 102a and 102d on both ends. Half (eight) vent holes 81a are blocked, and half (eight) vent holes 81a out of a total of sixteen that overlap each air suction port 103b are simultaneously opened, and the recording paper P is actually each vent hole 81a and the suction auxiliary hole 107a of each rib 101c~101d adsorbed on, than the total area of 107 b, small, towards the total area of the ventilation holes 81a that are open at the same time It made. As a result, the amount of air sucked from the air holes 81a opened simultaneously is suppressed, and the amount of air sucked from the air holes 81a and the suction auxiliary holes 107a and 107b that actually suck the recording paper P is reduced. The recording paper P is adsorbed satisfactorily by the four paper transport belts 81.

As described above, in the sheet feeding device 71 of the present embodiment, the area of the suction duct 85 in which the air on the outer peripheral side of each sheet conveying belt 81 is simultaneously sucked is defined as the effective suction area, that is, each air hole through which air is simultaneously sucked. Assuming that 81a and each suction auxiliary hole 107a, 107b are effective suction areas, this effective suction area is distributed so as to be smaller at both ends than the center side of each sheet conveying belt 81 in the direction orthogonal to the drawing direction E. since, at the time of adsorption of the recording paper P of smaller size than the total area of such the ventilation holes 81a that actually adsorb the recording paper P, it is more of the total area of such the ventilation holes 81a that are open at the same time small becomes, is suppressed suction amount of air from the vent holes 81a and the like that are open at the same time, not insufficient air suction amount from the vent holes 81a and the like that actually adsorb the recording paper P, It is possible to satisfactorily adsorb recording sheet P.

  Further, since the effective suction area is arranged symmetrically with respect to the center of the recording paper, the recording paper can be adsorbed with a good balance regardless of the size of the recording paper.

  FIGS. 14A and 14B are plan views showing modifications of the air suction ports formed on the curved surfaces 102a to 102d of the bottom plate 85g that are in sliding contact with the paper conveying belts 81 as viewed from below. In the modification of FIG. 14A, the air suction ports 111a to 111d are formed on the curved surfaces 102a to 102d of the bottom plate 85g, respectively. The overall shape of each of the air suction ports 111a to 111d is generally diamond-shaped, and the area of each of the air suction ports 111a and 111d on both ends is made smaller than the area of each of the air suction ports 111b and 111c on the center side, The effective suction area composed of the suction holes 81a is distributed so as to be smaller at both end sides than at the center side. 14B, the overall shape of the air suction ports 112a to 112d of the curved surfaces 102a to 102d is generally an isosceles triangle, and the area of each of the air suction ports 112a and 112d on both ends is the center. The air suction ports 112b and 112c on the side are made smaller than the area, and the effective suction region is distributed so as to be smaller on both end sides than on the central side.

  In the embodiment and the modified example, the area of the air suction ports on both ends is made smaller than the area of the air suction port on the center side, and the effective suction area is distributed so as to be smaller on both ends than the center side. However, the area of each air suction port is made constant, and the area of each ventilation hole 81a of each outer sheet conveyance belt 81 is made smaller than the area of each ventilation hole 81a of each sheet conveyance belt 81 on the center side. Also good. Alternatively, the area of each air suction port and the area of each ventilation hole 81a are made constant, and the distribution number (number per unit area) of each ventilation hole 81a of each outer sheet conveyance belt 81 is set to each sheet conveyance belt on the center side. The distribution number of the 81 air holes 81a may be smaller. Further, the curved surfaces 102a to 102d of the bottom plate 85g of the suction duct 85 may be changed to flat surfaces.

(About this embodiment)
The sheet feeding device according to the present embodiment stacks the sheet bundle on the sheet stacking table, sucks air from the outside of the sheet conveying member to the suction duct, and adsorbs the sheets of the sheet bundle to the sheet conveying member. In the sheet feeding device that conveys, if the area of the suction duct in which the air outside the sheet conveying member is simultaneously sucked is an effective suction area, the effective suction area is set in a direction orthogonal to the sheet conveying direction. The distribution is made to be smaller at both end sides than at the center side of the sheet conveying member.

In this embodiment , since the effective suction area in which air is simultaneously sucked is distributed so as to be smaller on both end sides than the center side of the paper transport member in the direction orthogonal to the paper transport direction, When attracting small-size recording paper, the area of the effective suction area that is open simultaneously on both outsides of the recording paper is reduced, and the amount of air sucked from the effective suction area that is simultaneously open is suppressed. Therefore, the recording paper can be satisfactorily adsorbed without a shortage of air sucked from the effective suction area where the ink is actually adsorbed.

For example, in the paper feeding device according to the present embodiment, the air holes of the paper transport member are overlapped with a plurality of air suction ports of the suction duct, and air is supplied to the air holes of the paper transport member and the air suction ports. Through the suction duct, and by making the area of each air suction port different between the central side and both end sides of the paper conveying member, the effective suction area is made to be more than the central side of the paper conveying member. The distribution is such that it becomes smaller at both ends.

Further, in the paper feeding device of the present embodiment, the air suction ports are arranged in a direction perpendicular to the paper transport direction and symmetrically with respect to the center of the paper, and are arranged symmetrically with each other. The area of each air suction port is set to be the same.

  In this case, the sheet can be adsorbed with a good balance.

Furthermore, in the paper feeding device according to the present embodiment, the air suction ports arranged on both ends of the paper transport member are divided across the air suction ports in a direction perpendicular to the paper transport direction. Each bridge is provided.

Such a bridge portion prevents the sheet conveying member from being sucked into the air suction port, thereby preventing the deformation of the sheet conveying member.

In the sheet feeding device of the present embodiment, the suction duct has a plurality of suction auxiliary ports provided at positions separated from the paper transport member, and the area of each suction auxiliary port is set to By differentiating between the center side and both end sides of the sheet conveying member, the effective suction area is distributed so as to be smaller at both end sides than the center side of the sheet conveying member.

  Also in this case, the effective suction area where air is sucked simultaneously can be distributed so as to be smaller at both ends than the center side of the paper transport member in the direction orthogonal to the paper transport direction.

Furthermore, in the paper feeding device according to the present embodiment, the paper transport member is a plurality of paper transport belts arranged in a direction orthogonal to the paper transport direction, and the suction duct is configured of each of the paper transport belts. A plurality of suction assist holes provided at a position between them, and the area of each suction assist hole is made smaller than the area of the air suction port.

  Even if the suction force of the sheet is increased by such a suction assist hole and the sheet transport member is sucked by the small suction assist hole, the sheet transport member is not deformed.

Further, in the sheet feeding device according to the present embodiment, each suction assisting hole has a respective bridge portion that is divided across the suction assisting holes in a direction orthogonal to the sheet conveyance direction.

  Such a bridge portion prevents the sheet conveying member from being sucked into the suction auxiliary hole, thereby preventing the deformation of the sheet conveying member.

Further, in the sheet feeding device of the present embodiment, the area of each suction auxiliary hole is made smaller at both end sides than the center side of the sheet conveying member.

  The area of each suction auxiliary hole opened simultaneously on both outer sides of the recording paper is reduced, the amount of air sucked from each suction auxiliary hole opened at the same time is suppressed, and each recording paper is actually adsorbed The amount of air sucked from the suction auxiliary hole is not insufficient, and the recording paper can be adsorbed satisfactorily.

For example, in the paper feeding device according to the present embodiment, the effective suction area is changed from the central side of the paper conveying member by making the area of each air hole different between the central side and both ends of the paper conveying member. Is also distributed so as to be smaller at both ends. Alternatively, the effective suction area is distributed to be smaller at both end sides than the center side of the sheet conveying member by making the distribution number of the air holes different between the center side and both end sides of the sheet conveying member. ing.

On the other hand, the image forming apparatus of this embodiment includes a sheet feeding device of the present embodiment.

Also in the image forming apparatus of the present embodiment described above, the same effects as the sheet feeding apparatus of the present embodiment.

In this embodiment , since the effective suction area in which air is simultaneously sucked is distributed so as to be smaller on both end sides than the center side of the paper transport member in the direction orthogonal to the paper transport direction, When attracting small-size recording paper, the area of the effective suction area that is open simultaneously on both outsides of the recording paper is reduced, and the amount of air sucked from the effective suction area that is simultaneously open is suppressed. Therefore, the recording paper can be satisfactorily adsorbed without a shortage of air sucked from the effective suction area where the ink is actually adsorbed.

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

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Document reader 11 Printing part 12 Paper conveyance part 13 Paper supply part 14 Large capacity paper feed cassette (LCC)
33 Paper transport path 71 Paper feeder 72 Outer frame body 73 Bottom plate 74 Paper stacking base 75 Paper drawer part 76 Paper rear end guides 77, 78 Assist ducts 79, 80 Assist fan 81 Paper transport belt (paper transport member)
81a Ventilation hole 82, 83 Roller 84 Intake / exhaust fan 85 Suction duct 86 Exhaust duct 103a, 103b Air suction port 103c, 107c Bridge part 104, 107a, 107b Suction auxiliary hole

Claims (12)

Stacked sheet bundle on the sheet stacking table, the air is sucked by the suction pull the duct, a paper feeding apparatus for transporting by adsorbing sheet of the sheet bundle in the sheet transport members,
The suction duct has a first air suction port formed at the center side in a direction orthogonal to the paper transport direction, and a second air suction port smaller than the first air suction port at both ends. A plurality of paper feed devices are formed along the paper transport direction . The sheet feeding device according to claim 1,
The sheet feeding device , wherein the suction duct has a suction auxiliary hole formed between the first air suction port and the second air suction port . The sheet feeding device according to claim 1 or 2,
A plurality of the first air suction ports are formed along a direction orthogonal to the sheet conveyance direction . The sheet feeding device according to claim 3 ,
The sheet feeding device, wherein the suction duct has suction auxiliary holes formed between the plurality of first air suction ports along a direction orthogonal to the sheet conveyance direction on the center side . A sheet feeding device according to any one of claims 1 to 4 ,
The paper feeding device, wherein the paper conveying member is a paper conveying belt having a plurality of air holes . A sheet feeding device according to any one of claims 1 to 5 ,
The sheet feeding device , wherein the suction duct is formed at a position where the first air suction port and the second air suction port overlap with the sheet conveying member . A sheet feeding device according to any one of claims 1 to 6 ,
In the suction duct, the first air suction port is formed at a position overlapping the paper transport member, and the suction duct is formed in the paper transport member between the first air suction port and the second air suction port. A sheet feeding device having suction assist holes formed at overlapping positions . A sheet feeding device according to any one of claims 1 to 7 ,
The paper conveying member is a plurality of paper conveying belts each having a plurality of vent holes,
The suction duct is provided between the first air suction port and the second air suction port respectively provided at positions overlapping with the plurality of paper transport belts, and between adjacent paper transport belts among the plurality of paper transport belts. And a suction auxiliary hole provided at the position of
A suction area formed by the suction auxiliary hole that is provided at a position between adjacent paper transport belts among the plurality of paper transport belts and sucks air is set to a center of the paper transport member in a direction orthogonal to the paper transport direction. A paper feeding device distributed so as to be smaller at the end side than at the side . A sheet feeding device according to any one of claims 1 to 8 ,
The overall shape of the first air suction port and the second air suction port is substantially rectangular, and the area of the second air suction port is smaller than the area of the first air suction port. A paper feeder characterized by that. A sheet feeding device according to any one of claims 1 to 8 ,
The overall shape of the first air suction port and the second air suction port is a substantially rhombus shape, and the area of the second air suction port is smaller than the area of the first air suction port. A paper feeder characterized by that. A sheet feeding device according to any one of claims 1 to 8,
The overall shape of the first air suction port and the second air suction port is a substantially isosceles triangle shape, and the area of the second air suction port is made smaller than the area of the first air suction port. A paper feeding device characterized by that. An image forming apparatus comprising the paper feeding device according to any one of claims 1 to 11.

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