JP2015040096A - Paper feeder and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder and an image formation apparatus that can prevent sheets from being fed one over another when conveying sheets one by one from a bundle of sheets placed on a sheet loading bed.SOLUTION: A paper feeder 71 includes: a sheet loading bed 74 where a sheet bundle is loaded; a sheet conveyance part which has a suction part for sucking air, and draws out and conveys a sheet of the sheet bundle loaded on the sheet loading bed 74 by suction by the suction part; and a blowout part which blows air out toward conveyance directional-side end parts of the sheets of the sheet bundle. The paper feeder detects a conveyance state of the sheet (S102) and adjusts the flow rate of the air (S104) according to the detection result (S103: YES).

Description

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

  An image forming apparatus such as a printer, a facsimile machine, or a copier, in which a paper feeding device having a paper feeding mechanism that pulls out and supplies paper from a paper stack placed on a paper stacking base forms an image on the supplied paper As widely used. In the paper feeding device, a technique for conveying the paper one by one from the paper stack loaded on the paper stacking base is required. If a double feed occurs in which a plurality of sheets are pulled out at once from a bundle of sheets stacked on the sheet stacking table, it may cause an abnormality such as a paper jam.

  Such a paper feeding device includes a paper transport belt disposed above the paper stacking base, and a fan that sucks air through a vent opening provided in the paper transport belt, and by suction of air through the vent hole. There is a method in which the uppermost sheet of the sheet bundle is sucked and conveyed by a sheet conveying belt.

  In addition, such a paper feeding device blows air toward the end of the paper bundle so that air is blown between the papers of the stacked paper bundle, and the paper bundles are dispersed. In some cases, it is easy to suck and pull out the sheets one by one.

  For example, Patent Document 1 discloses a paper feeder provided with a swinging actuator that operates in accordance with a change in the amount of air blown out.

  In a paper feeding device that uses air to prevent double feeding of paper, the optimal air flow varies depending on conditions such as the type of paper, so the air flow needs to be adjusted. Therefore, for example, the paper is classified into several types of paper such as plain paper and cardboard according to the basis weight of the paper, and the flow rate is determined by an appropriate value set in advance for each paper type.

JP 2011-184179 A

  However, there is a problem that the flow rate according to the paper classification is not necessarily an appropriate value. This is because, for example, the behavior of the paper with respect to the airflow changes depending on the paper cutting state, curl state, humidity control state, and the like.

  The present invention has been made in view of such a situation, and by adjusting the flow rate of air according to the conveyance state of the paper, the flow rate is optimized according to the state of the paper and other various situations, An object of the present invention is to provide a sheet feeding device capable of suppressing double feeding.

  Another object of the present invention is to provide an image forming apparatus including the paper feeding device according to the present invention.

  In order to solve the above problems, a paper feeding device according to the present invention has a paper stacking table on which a stack of sheets is stacked and a suction unit that sucks air, and is loaded on the paper stacking table by suction of the suction unit. A sheet conveying section that sucks the sheets in the sheet bundle and conveys the sucked sheets, and a blowout section that blows air toward the end of the sheet bundle in the sheet conveyance direction, and conveys the sheets in the sheet bundle A sheet feeding device that supplies a supply destination via a path, comprising: a detection unit that detects a conveyance state of a sheet; and an adjustment unit that adjusts an air flow rate according to a detection result of the detection unit. Features.

  In the sheet feeding device according to the present invention, the adjusting unit adjusts at least one of an amount of suction by the suction unit and an amount of blowing from the blowing unit.

  Further, in the paper feeding device according to the present invention, the detection means is a multi-feed detection unit that detects that a plurality of sheets are pulled out from a bundle of sheets stacked on the sheet stacking table, and the adjustment The means adjusts the flow rate of the air when the multi-feed detection unit detects that a plurality of sheets have been taken out.

  Further, in the sheet feeding device according to the present invention, the detection unit is a timing unit that counts the conveyance time from the start of conveyance to a predetermined position in the conveyance path, and the adjustment unit is timed by the timing unit. The air flow rate is adjusted according to the conveyance time.

  The image forming apparatus according to the present invention includes the sheet feeding device and an image forming unit that forms an image on a sheet supplied from the sheet feeding device.

  The sheet feeding device and the image forming apparatus according to the present invention adjust the flow rate of air in accordance with the sheet conveyance status. With this configuration, it is possible to adjust the flow rate according to various conditions such as the cutting state, curl state, and humidity control state of the paper as well as the classification according to the basis weight of the paper, thus suppressing double feeding of paper. It has an excellent effect such as being able to do so.

1 is a schematic cross-sectional view illustrating an example of an image forming apparatus to which a paper feeding device according to the present invention is applied. It is a schematic plan view showing an example of a paper feeding device according to the present invention. It is a schematic front view which shows an example of the paper feeder which concerns on this invention. It is a schematic perspective view which shows an example of the paper feeder which concerns on this invention from the viewpoint from diagonally backward. It is a schematic perspective view which shows an example of the paper drawer part of the paper feeder which concerns on this invention from the viewpoint from diagonally upward front. It is a schematic perspective view which shows an example of the paper drawer part of the paper feeder which concerns on this invention from the viewpoint from diagonally upward and rear. It is a schematic perspective view which shows an example of the paper drawer part of the paper feeder which concerns on this invention from the viewpoint from diagonally lower back. FIG. 4 is an enlarged schematic plan view illustrating an example of a member such as a sheet conveying belt in a sheet drawing unit of the sheet feeding device according to the present invention. FIG. 3 is a schematic side cross-sectional view schematically showing a configuration example of a paper drawing unit and its periphery of the paper feeding device according to the present invention. 1 is a block diagram illustrating a configuration example of an image forming apparatus and a sheet feeding device according to the present invention. FIG. 3 is a schematic side cross-sectional view schematically showing a configuration example of a paper drawing unit and its periphery of the paper feeding device according to the present invention. FIG. 3 is a schematic side cross-sectional view schematically showing a configuration example of a paper drawing unit and its periphery of the paper feeding device according to the present invention. 6 is a flowchart illustrating an example of a first adjustment process of a sheet feeding device included in the image forming apparatus according to the present invention. 6 is a flowchart illustrating an example of a second adjustment process of a sheet feeding device included in the image forming apparatus according to the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiment is an example embodying the present invention, and is not intended to limit the technical scope of the present invention.

(First embodiment)
FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus to which a paper feeding device according to the present invention is applied. 1 shows an example in which the paper feeding apparatus according to the present invention is applied to an image forming apparatus 1 such as a printer, a facsimile machine, or a copier. The image forming apparatus 1 includes various mechanisms such as 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. A paper feeding device 71 (see FIG. 2) according to the present invention, which will be described later, is applied to the large capacity paper feeding cassette 14.

  The image forming apparatus 1 acquires image data by reading a document image by the document reading device 2 or receiving image data input from an external device. The image forming apparatus 1 performs various image processing on the image data as necessary, and then displays an image indicated by the image data by the printing unit 11 on the sheet supply unit 13 or a sheet feeding device 71 described later. Formed on the recording paper supplied from the printer.

  A photosensitive drum 21 is disposed at the approximate center of the printing unit 11, and a charging device 22, a laser exposure device 23, a developing device 24, a transfer roller 25, and a cleaning device 26 are disposed around the photosensitive drum 21.

  The photosensitive drum 21 has a photosensitive layer on its surface. The surface of the photosensitive drum 21 is rotated by the cleaning device 26 while being rotated in the direction of the arrow shown in the figure. Is charged. The laser exposure device 23 is a laser scanning unit (LSU) including a laser diode and a reflection mirror, and receives image data, modulates the intensity of the laser beam according to the image data, and uses the photosensitive drum 21 with the laser beam. The surface is scanned and an electrostatic latent image is written on the surface of the photosensitive drum 21. The developing device 24 develops the electrostatic latent image on the surface of the photosensitive drum 21 with toner to form a toner image on the surface of the photosensitive drum 21.

  The transfer roller 25 is pressed against the photosensitive drum 21, forms a nip area with the photosensitive drum 21, and rotates together with the photosensitive drum 21. The photoconductive drum 21 and the transfer roller 25 transfer the toner image on the surface of the photoconductive drum 21 onto the recording paper while the recording paper conveyed through the conveying path 33 is sandwiched and conveyed in the nip region.

  A fixing device 27 is disposed above the printing unit 11. The fixing device 27 includes a heating roller 28 and a pressure roller 29 that are pressed against each other. The recording paper is sandwiched in a nip region between the heating roller 28 and the pressure roller 29 to heat and heat the recording paper. The toner image transferred onto the recording paper is fixed by applying pressure. The recording sheet is conveyed from the fixing device 27 to the discharge roller pair 36 and is discharged to the discharge tray 37 by the discharge roller pair 36.

  On the other hand, the paper transport unit 12 includes a plurality of transport roller pairs 31, a registration roller pair 32, a transport path 33, a detour path 34, a branching claw 35, a paper discharge roller pair 36, a paper discharge tray 37, and the like for transporting recording paper. It has a mechanism related to the conveyance.

  The paper supply unit 13 includes a plurality of paper supply cassettes 38. Each paper feed cassette 38 is a tray for storing recording paper, and is provided in a plurality of stages below the image forming apparatus 1. Each paper feed cassette 38 is provided with members such as respective pickup rollers 39 for pulling out the recording paper one by one and feeding it to the transport path 33. The transport path 33 of the paper transport unit 12 feeds the pulled out recording paper. To send to.

  The large-capacity paper feed cassette (LCC) 14 can store a large amount of recording paper, and similarly to each paper feed cassette 38, the recording paper is pulled out one by one and sent out to the transport path 33.

  In the conveyance path 33, the recording sheet pulled out from one of the paper feed cassettes 38 is conveyed in the sheet conveyance direction C and transferred to the registration roller pair 32, and the leading end of the recording sheet is temporarily stopped. The recording paper is bent against the recording paper 32, and the leading edge of the recording paper is aligned in parallel with the registration roller pair 32 by the elastic force of the recording paper, and then the rotation of the registration roller pair 32 is started. As a result, the recording sheet is conveyed to the nip region between the photosensitive drum 21 and the transfer roller 25. The recording sheet passes through the nip area between the photosensitive drum 21 and the transfer roller 25, is transferred with the toner image, passes through the nip area between the heating roller 28 and the pressure roller 29, and then passes through the nip area. The image is fixed, conveyed in the forward direction A by the discharge roller pair 36, and discharged to the discharge tray 37.

  When printing an image on the back side of the recording paper, the paper discharge roller pair 36 is stopped while the recording paper is conveyed in the forward direction A and discharged to the paper discharge tray 37, that is, the recording paper is sandwiched. In this state, the paper discharge roller pair 36 is stopped. Then, after switching the branching claw 35 in the obliquely downward direction, the paper discharge roller pair 36 is rotated in the reverse direction to convey the recording paper in the reverse direction B to the detour path 34, and through the detour path 34, the transport path 33. Then, the recording paper is returned to the registration roller pair 32.

  Such switching of the conveyance direction of the recording paper is referred to as switchback conveyance. By this switchback conveyance, the front and back sides of the recording paper are reversed, and at the same time, the leading edge and the trailing edge of the recording paper are switched. Therefore, when the recording paper is reversed and returned, the trailing edge of the recording paper comes into contact with the registration roller pair 32, and the trailing edge of the recording paper is aligned parallel to the registration roller pair 32. Is conveyed from the rear end to the nip region between the photosensitive drum 21 and the transfer roller 25, and printing is performed on the back surface of the recording paper. The toner image is formed on the back surface of the recording paper by the heating roller 28 and the pressure roller 29. Fixing is performed, and the recording paper is discharged to the paper discharge tray 37 via the paper discharge roller pair 36.

  Next, the document reading device 2 mounted on the upper part of the main body of the image forming apparatus 1 will be described. The document reading device 2 includes a lower first reading unit 41 and an upper document conveying unit 42. The document conveying unit 42 is pivotally supported by the back side of the first reading unit 41 by a hinge (not shown) and opened and closed by moving the front portion up and down. When the document conveying unit 42 is opened, the platen glass 44 of the first reading unit 41 is opened, and a document sheet is placed on the platen glass 44.

  The first reading unit 41 includes a mechanism related to image reading, such as a platen glass 44, a first scanning unit 45, a second scanning unit 46, an imaging lens 47, a CCD (Charge Coupled Device) 48, and the like. The first scanning unit 45 includes a light source 51 and a first reflection mirror 52. The first scanning unit 45 illuminates the surface of the original paper on the platen glass 44 with the light source 51 while moving at a constant speed V in the sub-scanning direction according to the size of the original paper, and reflects the reflected light. Is reflected by the first reflecting mirror 52 and guided to the second scanning unit 46. As a result, the image on the surface of the original paper is scanned in the sub-scanning direction. The second scanning unit 46 includes a second reflecting mirror 53 and a third reflecting mirror 54. The second scanning unit 46 follows the first scanning unit 45 and moves at a speed V / 2, while reflecting the reflected light from the document sheet to the second. The light is reflected by the reflection mirror 53 and the third reflection mirror 54 and guided to the imaging lens 47. The imaging lens 47 focuses the reflected light from the original paper on the CCD 48 and forms an image on the original paper surface on the CCD 48. The CCD 48 repeatedly scans the image on the surface of the original paper in the main scanning direction, and outputs a analog image signal of the main scanning line each time.

  Further, the first reading unit 41 can read not only a stationary document but also an image on the surface of the document sheet conveyed by the document conveying unit 42. In this case, as shown in FIG. 1, the first scanning unit 45 is moved to a reading position below the original reading glass 55, and the second scanning unit 46 is positioned in accordance with the position of the first scanning unit 45. Then, the conveyance of the original sheet by the original conveying unit 42 is started.

  The document transport unit 42 pulls the document paper by rotating the pickup roller 56 while pressing the pickup roller 56 against the document paper on the document tray 57. Then, the document conveying unit 42 conveys the document sheet through the document conveying path 58, passes the document sheet over the document reading glass 55 of the first reading unit 41, and further passes under the second reading unit 43 to discharge the document. The paper is conveyed from the roller pair 61 to the paper discharge tray 62.

  When transporting the original paper, the light source 51 of the first scanning unit 45 illuminates the original paper surface via the original reading glass 55, and reflects the reflected light from the original paper to each of the first scanning unit 45 and the second scanning unit 46. The light is guided to the imaging lens 47 by a reflection mirror. Reflected light from the original paper is condensed on the CCD 48 by the imaging lens 47, and an image on the original paper surface is formed on the CCD 48. The formed image on the surface of the original paper is read by the CCD 48.

  Further, at the same time as reading the image on the front surface of the original paper transported by the original transport unit 42, the second reading unit 43 incorporated in the original document transport unit 42 can read the image on the back side of the original paper. The second reading unit (hereinafter referred to as CIS) 43 is a contact print image sensor (Contact Image Sensor (CIS)) and is disposed above the platen glass 44. The document sheet that has passed over the document reading glass 55 of the first reading unit 41 passes under the CIS 43 and is discharged to the sheet discharge tray 62. When the document sheet passes, the CIS 43 illuminates the back surface of the document sheet, receives reflected light from the document sheet, and reads an image on the back surface of the document sheet.

  The original paper image read by the CCD 48 and the CIS 43 in this way is output as an analog image signal from the CCD 48 and the CIS 43, and the analog image signal is A / D converted into a digital image signal. The digital image signal (image data) is subjected to various image processing and then transmitted to the laser exposure device 23 of the image forming apparatus 1, and an image is formed on the recording paper in the image forming apparatus 1. The paper is output as a copy original.

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

  FIG. 2 is a schematic plan view showing an example of the paper feeding device 71 according to the present invention, and FIG. 3 is a schematic front view showing an example of the paper feeding device 71 according to the present invention. As shown in FIGS. 2 and 3, the sheet feeding device 71 includes an outer frame 72, a bottom plate 73, a sheet stacking plate 74 disposed inside the outer frame 72, and a sheet disposed above one end of the outer frame 72. A mechanism such as a drawer 75 is provided.

  The paper stacking table 74 is used for stacking a large amount of recording paper as a paper bundle, and is provided inside the outer frame 72 so as to be lifted and lowered. An opening 74 a that is long in the recording paper drawing direction (feeding and transporting direction) E is formed in the paper stacking table 74. 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 base 74. The recording paper drawing direction E is referred to as the front, and the direction opposite to the drawing direction E is referred to as the back.

  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 as indicated by double arrows in a direction orthogonal to the pull-out direction E, and are interlocked so as to approach each other or to be separated from each other. Can be moved.

  The paper drawing unit 75 includes a mechanism related to conveyance of four paper conveyance belts 81, a pair of rollers 82 and 83, an intake / exhaust fan 84, an intake duct 85, an exhaust duct 86, etc. Yes. Each paper transport belt 81 is formed with a large number of air holes 81 a, and air is sucked from the air holes 81 a of each paper transport belt 81 to the intake / exhaust fan 84 through the intake duct 85. 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 schematic perspective view showing an example of a sheet feeding device 71 according to the present invention from a perspective from obliquely rearward. FIG. 4 shows the internal configuration of the outer frame 72, the bottom plate 73, the paper stacking board 74, and the like from obliquely rearward with the paper drawer 75 of the paper feeder 71 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. The air sucked by the assist fans 79 and 80 is sent to the ventilation passages of the assist ducts 77 and 78, and the sent air is sent from the exhaust ports 77 a and 78 a of the assist ducts 77 and 78 to the outer frame 72. Blown out inside.

  As shown in FIGS. 2 and 4, the paper trailing edge guide 76 can reciprocate along the drawing direction E of the recording paper, and is positioned at an arbitrary position along 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 perpendicular to the drawing direction E, and is positioned at an arbitrary position along the direction perpendicular to the drawing direction E. .

  The stacking of the sheet bundle on the sheet stacking board 74 will be described. When stacking, the paper trailing edge guide 76 is moved backward to widen the space between the paper trailing edge guide 76 and the contact plate 72 b of the outer frame 72. Further, the assist ducts 77 and 78 are moved in a direction away from each other so that the space between the assist ducts 77 and 78 is widened. In this state, the sheet bundle is stacked on the sheet stacking board 74. Then, the sheet trailing edge guide 76 is moved in the drawing direction E, 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, and the sheet bundle is slid on the sheet stacking table 74 and moved. . Further, the front end of the sheet bundle is brought into contact with the contact plate 72b of the outer frame body 72, and the front end and rear end of the sheet bundle are formed between the column portion 76a of the paper rear end guide 76 and the contact plate 72b of the outer frame body 72. Position between them. 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 body 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 to 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 winding 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 or 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 rotates in the take-up direction, each wire 87 is taken up by each take-up pulley 89 and the paper stacking table 74 is raised. When each take-up pulley 89 rotates in the opposite direction, each wire 87 is drawn out from each take-up pulley 89, and the paper 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. Further, the height of the uppermost layer of the sheet bundle on the sheet stacking table 74 is detected by a height position sensor 93 provided on the head 76 b of the sheet trailing edge guide 76.

  Next, the configuration of the paper drawer 75 will be described in detail. FIG. 5 is a schematic perspective view showing an example of the paper drawing portion 75 of the paper feeding device 71 according to the present invention as seen from a diagonally upper front. FIG. 6 is a schematic perspective view showing an example of the sheet drawing portion 75 of the sheet feeding device 71 according to the present invention from a perspective from obliquely upward and rearward. FIG. 7 is a schematic perspective view showing an example of the sheet drawing portion 75 of the sheet feeding device 71 according to the present invention from a perspective from obliquely below and rearward. FIG. 8 is an enlarged schematic plan view showing an example of a member such as a paper conveying belt in the paper drawing unit 75 of the paper feeding device 71 according to the present invention.

  As shown in FIGS. 5, 6, and 7, the sheet drawing unit 75 includes four sheet conveying belts 81, a pair of rollers 82 and 83 that bridge the respective sheet conveying belts 81, an intake / exhaust fan 84, an intake duct 85, A mechanism for pulling out the paper such as the exhaust duct 86 is provided.

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

  Further, the upper surface 85b and the lower surface 85g of the intake duct 85 are formed in a planar shape. 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. ing.

  A plurality of ribs 85j that are long in the pull-out direction E are formed side by side on the lower surface 85g of the intake duct 85. As shown in an enlarged plan view in FIG. 8, a plurality of intake holes 85 e communicating with the ventilation path of the intake duct 85 are formed between the ribs 85 j on the lower surface 85 g of the intake duct 85.

  Then, the transport motor 107 rotationally drives the front roller 82 in the arrow direction D (see FIG. 5), the rear roller 83 is driven to rotate, and each paper transport belt 81 rotates in the arrow direction D. At this time, each sheet conveying belt 81 is in sliding contact with each rib 85j formed on the lower surface 85g of the intake duct 85.

  As shown in FIG. 8, the air holes 81a of the paper transport belt 81 are formed in a plurality of rows along the pull-out direction E, and these rows are formed at the same intervals as the ribs 85j. A sheet conveying belt 81 is bridged so as to be positioned between the ribs 85j. Therefore, a space surrounded by the ribs 85j, the sheet conveying belt 81, and the lower surface 85g of the intake duct 85 is formed between the ribs 85j. For the formed space, the air holes 81a of the paper conveyance belt 81 and the air intake holes 85e on the lower surface 85g of the air intake duct 85 serve as air inlets and outlets. For this reason, when the air in the intake duct 85 is sucked by the intake / exhaust fan 84, the air flows into the intake holes 85e of the lower surface 85g of the intake duct 85 through the air holes 81a of the paper transport belt 81 and the spaces. The air flows through the intake duct 85 to the intake / exhaust fan 84. As a result, the recording sheet can be adsorbed to the lower surface of each sheet conveying belt 81 and conveyed.

  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, as shown in FIG. 7, each exhaust port 86 b communicating with the ventilation path of the exhaust duct 86 is formed in 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 the contact plate 72 b of the outer frame body 72, and each exhaust port 86 b of the exhaust duct 86 forms a notch 72 c of the contact plate 72 b of the outer frame body 72. Via the outer frame 72. 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.

  Next, the process of placing the recording paper on the paper feeding device 71 and the process of transporting the placed recording paper will be described with reference to FIGS. 5 to 8 and FIG. 9 described above. FIG. 9 is a schematic cross-sectional side view schematically showing a configuration example of the paper drawing portion 75 of the paper feeding device 71 according to the present invention and its surroundings. FIG. 9 schematically shows a state in which a bundle of sheets stacked on the sheet feeding device 71 is conveyed. First, in the paper feeding device 71, the paper bundle is placed on the paper stacking board 74, and the front and rear ends of the paper bundle are placed between the column portion 76 a of the paper rear end guide 76 and the contact plate 72 b of the outer frame 72. The both ends of the sheet bundle are sandwiched between the assist ducts 77 and 78 for positioning. Then, each take-up pulley 89 is rotated in the take-up direction by the pulse motor 92 to raise the paper stacking table 74. At this time, when the uppermost sheet of the sheet stack on the sheet stacking board 74 is detected by the height position sensor 93, that is, when the uppermost sheet reaches the detection reference height, the pulse motor 92 is stopped. Then, the height of the uppermost sheet is set to the detection reference height, or the rotation direction and the rotation angle of the pulse motor 92 are further controlled to adjust and set the height of the uppermost sheet. Also, air is sent from the assist fans 79 and 80 to the assist ducts 77 and 78, and the air is exhausted from the exhaust ports 77a and 78a of the assist ducts 77 and 78 on both sides near the front end of the sheet stack loaded on the sheet stacking board 74. Air is blown onto the upper layer of the surface, allowing air to enter between the sheets and causing the sheets to scatter.

  Furthermore, air is sent from the intake / exhaust fan 84 to the exhaust duct 86, and air is blown from the exhaust ports 86b of the exhaust duct 86 onto the upper layer of the front end surface of the sheet bundle so that air enters between the sheets, To disperse. As a result, the adhesion of each sheet in the upper layer of the sheet bundle is reduced, the sheet can be easily pulled out from the sheet bundle, and the sheets can be easily pulled out one by one.

  In this state, air is sucked from the intake duct 85 to the intake / exhaust fan 84, and the air is sucked through the air holes 81a of the paper conveying belt 81 and the air holes 85e of the lower surface 85g of the air intake duct 85, and the rollers 82. , 83 are intermittently rotated, and the respective sheet conveying belts 81 are intermittently moved around. As a result, one recording sheet is attracted to the lower surface of each sheet conveying belt 81, and the recording sheet is pulled out in the drawing direction E by each sheet conveying belt 81 and conveyed to the conveying roller pair 31 of the image forming apparatus 1. The recording paper is conveyed through the conveyance path 33. Subsequently, the next sheet of recording paper is adsorbed to the lower surface of each paper conveying belt 81, and the recording paper is drawn in the drawing direction E by each paper conveying belt 81 and conveyed to the conveying roller pair 31, and so on. The recording paper is attracted to the lower surface of each paper transport belt 81, and the recording paper is pulled out in the drawing direction E by each paper transport belt 81 and transported.

  On the transport path 33, a paper front end sensor 106 that detects the front end of the recording paper is disposed on the front side of the transport roller pair 31. The paper leading edge sensor 106 is configured by using an optical sensor, and detects that the leading edge of the conveyed recording paper has passed. In addition, a double feed sensor 108 is arranged from the inside to the bottom of the sheet conveying belt 81 that circulates below the rollers 82 and 83. The double feed sensor 108 is disposed in front of the outer frame 72 on the front side of the paper stacking table 74, and optically detects the occurrence of so-called accompanying feeding in which a plurality of recording papers are simultaneously fed. When the double feed sensor 108 detects double feed, the double feed sensor 108 outputs a double feed detection signal to the control unit 101 and / or the paper feeding device 71 described later.

  Next, the configuration of the control system of the image forming apparatus 1 and the paper feeding device 71 according to the present invention will be described.

  FIG. 10 is a block diagram illustrating a configuration example of the image forming apparatus 1 and the paper feeding device 71 according to the present invention. The image forming apparatus 1 includes a control unit 101 and an input operation unit 102, in addition to the document reading device 2, the printing unit 11, the paper transport unit 12, the paper supply unit 14 (large-capacity paper feed cassette 14), and the paper feed device 71. Various devices and mechanisms such as a memory 103 and an image processing unit 104.

  The control unit 101 is a mechanism that integrally controls the image forming apparatus 1 and the sheet feeding device 71. The control unit 101 includes circuits such as a CPU, a RAM, a ROM, and various other interfaces.

  The input operation unit 102 includes mechanisms such as a plurality of operation keys, a liquid crystal panel, and a liquid crystal touch panel, and serves as a man-machine interface for displaying and inputting various information.

  The memory 103 is a mechanism such as a hard disk drive (HDD) that records information such as various programs and data.

  The image processing unit 104 is a mechanism that performs various types of image processing based on image data.

  Further, the paper feeding device 71 includes various mechanisms such as the size detecting unit 105 and the time measuring unit 109 in addition to the above-described height position sensor 93, the paper leading edge sensor 106, and the double feed sensor 108.

  The size detection unit 105 detects, for example, the position of the sheet trailing edge guide 76 in the drawing direction E and the position of the assist ducts 77 and 78 in the direction orthogonal to the drawing direction E in the sheet feeding device 71 and corresponds to these positions. This is a mechanism for outputting a detection output indicating the size of the recording paper to be printed.

  The time measuring unit 109 is a mechanism that measures the time from the start of conveyance of the recording paper until the paper leading edge sensor 106 detects the leading edge of the recording paper.

  In the sheet feeding device 71 configured as described above, various types of recording sheets are stacked on the sheet stacking board 74, so that recording is performed on the lower surface of each sheet conveying belt 81 regardless of the type of recording sheet. It is necessary to suck out the paper.

  However, when various conditions such as the type of recording paper change, the recording paper attracting state on the lower surface of each paper conveying belt 81 varies, and a recording paper conveyance error may occur. For example, there are various types of recording paper having different sizes, basis weights, air permeability, and the like, and the proper suction conditions for the recording paper differ depending on these types.

  The size of the recording paper is generally a standard size such as B5, A4, B4, etc. When the size of the recording paper changes, the weight of the recording paper changes. The basis weight of the recording paper is the weight per unit area of the recording paper. When the basis weight of the recording paper changes, the weight and rigidity of the recording paper change. If the recording paper becomes too heavy, even if the air is sucked from the air holes 81 a of the paper transport belt 81, the recording paper is not easily lifted and it is difficult to attract the recording paper to the lower surface of each paper transport belt 81. . Further, if the recording paper is too rigid, the recording paper is difficult to adhere to the lower surface of each paper conveying belt 81, and it is difficult to attract the recording paper to the lower surface of each paper conveying belt 81.

  The air permeability is the speed at which air escapes from one side of the recording paper to the other side, and is the ease of air escape. If the air permeability is excessively large, when air is sucked from the air holes 81a of the paper transport belt 81, the air is released from the lower surface to the upper surface of the recording paper, and the recording paper is hardly lifted. It becomes difficult to attract the recording paper to the lower surface of the belt 81.

  As described above, since the proper suction condition varies depending on the type of recording paper, if the proper suction condition is not set, an abnormality occurs in the suction of the recording paper to the lower surface of each paper transport belt 81, and the recording paper There is a risk of transport errors. In addition, not only the type of recording paper, but also the proper suction conditions vary depending on the cutting state, curl state, humidity control state, and the like of the recording paper.

  Next, occurrence of double feeding of recording sheets will be described. 11A and 11B are schematic cross-sectional side views schematically showing an example of the configuration of the paper drawing portion 75 of the paper feeding device 71 according to the present invention and its periphery. FIG. 11A shows a state where the conveyance is normally performed, and FIG. 11B shows a state where an abnormality has occurred in the conveyance.

  11A and 11B show a state after one recording sheet is conveyed. As shown in FIG. 11A, when the conveyance is performed normally, the recording sheets are pulled out one by one and conveyed, so that all the remaining recording sheets remain on the sheet stacking board 74. It is a state.

  However, even when the sheets are conveyed one by one, there may be a case where a multiple feed (carrying feed) in which a plurality of sheets are pulled out from the sheet stacking table 74 may occur. In such a case, one stacked uppermost recording sheet is conveyed, and the next recording sheet pulled out together with the uppermost recording sheet is disposed in the exhaust duct 86 positioned in front of the paper feeding device 71. There is a case where only a part of the inner wall surface 86d protrudes from the sheet feeding device 71 without reaching the conveyance path 33. FIG. 11B shows a state in which such a conveyance error has occurred, and the recording sheet pulled out together with the recording sheet located in the upper layer protrudes from the sheet feeding device 71 beyond the outer frame 72, The uppermost recording sheet is in contact with the inner wall surface 86 d of the exhaust duct 86.

  If such a transport error continues, a plurality of recording sheets are transported to the transport path 33 and may cause a trouble such as a transport trouble. Therefore, the transport condition such as suction is corrected to prevent the trouble from occurring. There is a need.

  When the uppermost recording sheet protrudes from the paper feeding device 71 due to such a conveyance error, since the protruding uppermost recording sheet has already been partially pulled out during the next conveyance, the conveyance starts. Therefore, the time for transporting from the transport path 33 to the transport path 33 is shortened compared to the normal time. Therefore, whether or not a conveyance error has occurred due to the accompanying feeding by measuring the time from the start of conveyance until the paper leading edge sensor 106 disposed on the conveyance path 33 detects the leading edge of the recording paper being conveyed. It is possible to determine whether or not.

  Further, whether or not the uppermost recording sheet protrudes from the sheet feeding device 71 can be optically detected by a double feed sensor 108 disposed inside the sheet conveying belt 81.

  Therefore, in the paper feeding device 71 according to the present invention, by correcting the conveyance conditions based on the detection result of the paper leading edge sensor 106 and / or the double feed sensor 108, an abnormality such as a conveyance trouble is prevented in advance. ing. The conveyance condition to be corrected is adjustment of the flow rate of air, such as adjustment of the amount of air blown from the exhaust duct 86 and adjustment of the amount of suction by the intake duct 85.

  Next, processing of the image forming apparatus 1 and the paper feeding device 71 according to the present invention will be described.

  FIG. 12 is a flowchart showing an example of the first adjustment process of the paper feeding device 71 provided in the image forming apparatus 1 according to the present invention. The first adjustment process is a process of adjusting the air flow rate using the paper leading edge sensor 106.

  Based on the control of the control unit 101 provided in the image forming apparatus 1, the paper feeding device 71 starts a paper feeding process (S101). The start of the paper feed process in step S101 is one sheet or a plurality of recording sheets from the paper stacking base 74 to the transport path 33 for the purpose of image forming or the like from the uppermost layer of the stack of sheets stacked. This is a process for starting the process of sending out one by one. Note that, at the start of the paper feed process, the blowout amount from the exhaust duct 86 and the suction amount by the intake duct 85 are set to initial values. The initialization process for setting the blowout amount and the suction amount to the initial values is executed at an appropriately determined timing such as when a new paper feed job is started or when the consumables of the image forming apparatus 1 are replaced.

  The paper feeding device 71 measures the passage time to the passage point of the recording paper sent out from the paper stacking board 74 by the time measuring unit 109 (S102). In step S102, the time from the paper conveyance start time until it passes the passing point is measured. The sheet conveyance start time indicates the time when the process of pulling out the uppermost sheet of the stacked recording sheets from the sheet stacking board 74 is started. The time of passing the passing point indicates the time when the paper leading edge sensor 106 detects the leading edge of the recording paper that is transported along the transport path 33.

  The paper feeding device 71 compares the time measured by the time measuring unit 109 in step S102 with a predetermined time set in advance, and determines whether or not the measured time is within the predetermined time (S103). As shown in FIG. 11B, when a part of the stacked uppermost recording sheet protrudes from the sheet stacking No. 74, the recording sheet that has been pulled out from the conveyance start time by the amount that has been pulled out. The time to pass the passing point is shortened. Therefore, by setting an appropriate predetermined time, when the time measured by the time measuring unit 109 is within the predetermined time, it can be estimated that there is a possibility that a carry-on has occurred.

  In step S103, when it is determined that the passage time is within the predetermined time (S103: YES), the sheet feeding device 71 decreases the suction amount by the intake duct 85 and increases the discharge amount from the exhaust duct 86 ( S104). By suppressing the suction amount by the intake duct 85, it is possible to prevent a plurality of recording sheets from being sucked up and to prevent the occurrence of double feeding. Further, by increasing the amount of air blown out from the exhaust duct 86, it is possible to increase the efficiency of handling the stacked sheet bundle, separate the individual recording sheets that overlap, and prevent the occurrence of double feeding. Note that the increase level of the blowout amount and the decrease level of the suction amount are adjusted using preset values. For example, when the flow rate ratio between the suction amount and the blowing amount is set to 50:50 as the initial value, the suction amount and the blowing amount are adjusted to 20:80.

  After adjusting the suction amount and the blowout amount, the sheet feeding device 71 determines whether or not all sheet feeding processes have been completed (S105). If it is determined in step S105 that all paper feed processes have been completed (S105: YES), the first adjustment process is terminated. If it is determined that the paper feed process has not ended (S105: NO), the end determination in step S105 is repeated until the paper feed process ends.

  In step S103, when it is determined that the passage time exceeds the predetermined time (S104), the sheet feeding device 71 determines whether or not all sheet feeding processes have been completed (S106). If it is determined in step S106 that all paper feed processes have been completed (S106: YES), the first adjustment process is terminated.

  If it is determined in step S106 that the paper feed process has not ended (S106: NO), the paper feed device 71 repeats the processes in and after step S102. That is, the passage time of the recording sheet to be conveyed next is measured, and the air flow rate is adjusted as necessary.

  In this way, the first adjustment process is performed.

  As described above, the sheet feeding device 71 according to the first embodiment and the image forming apparatus 1 using the sheet feeding device 71 adjust the air flow rate according to the conveyance state of the recording sheet. Specifically, when it is determined that the passage time from the start of conveyance to a predetermined position in the conveyance path exceeds a predetermined time, the suction amount is decreased and the blowout amount is increased. Thereby, since the flow rate can be optimized according to the state of the recording paper and various other conditions, it is possible to suppress double feeding of the recording paper.

(Second Embodiment)
The second embodiment is a form in which a double feed sensor is used for detection of a sheet conveyance state in the first embodiment. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the first embodiment is referred to, and the description thereof is omitted.

  In the second embodiment, instead of the first adjustment process according to the first embodiment, a second adjustment process using the double feed sensor 108 is executed. FIG. 13 is a flowchart showing an example of the second adjustment process of the paper feeding device 71 provided in the image forming apparatus 1 according to the present invention. The second adjustment process is a process of adjusting the air flow rate using the double feed sensor 108.

  Based on the control of the control unit 101 provided in the image forming apparatus 1, the paper feeding device 71 starts a paper feeding process (S201).

  The paper feeding device 71 determines whether or not the double feed sensor 108 has detected double feed every time the recording paper is pulled out from the paper stacking base 74 and conveyed to the conveyance path 33 (S202). The determination of double feed detection is made based on whether or not the double feed sensor 108 outputs a double feed detection signal.

  If it is determined in step S202 that double feeding has been detected (S202: YES), the paper feeder 71 reduces the amount of suction by the intake duct 85 and increases the amount of blown air from the exhaust duct 86 (S203).

  After adjusting the suction amount and the blowout amount, the paper feeding device 71 determines whether or not all the paper feeding processes have been completed (S204). If it is determined in step S204 that all paper feed processes have been completed (S204: YES), the second adjustment process is terminated. If it is determined that the paper feed process has not been completed (S204: NO), the determination process in step S04 is repeated until the paper feed process is completed.

  If it is determined in step S202 that double feed has not been detected (S202: NO), the sheet feeder 71 determines whether or not all sheet feeding processes have been completed (S205). If it is determined in step S205 that all paper feed processes have been completed (S205: YES), the second adjustment process is terminated.

If it is determined in step S205 that the paper feed process has not ended (S205: N
), The paper feeding device 71 repeats the processing after step S202. That is, after the recording sheet is transported next, it is determined whether or not the double feed sensor 108 detects double feed, and the air flow rate is adjusted as necessary.

  In this way, the second adjustment process is performed.

  As described above, the sheet feeding device 71 according to the second embodiment and the image forming apparatus 1 using the sheet feeding device 71 adjust the air flow rate according to the conveyance state of the recording sheet. Specifically, when the double feed sensor 108 detects double feed, the suction amount is decreased and the blowout amount is increased. Thereby, since the flow rate can be optimized according to the state of the recording paper and various other conditions, it is possible to suppress double feeding of the recording paper.

(Third embodiment)
In the first embodiment, the air flow rate is adjusted a plurality of times in the first embodiment. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the first embodiment is referred to, and the description thereof is omitted.

  In the third embodiment, adjustment is not performed once per job, but the adjustment amount is classified finely and the flow rate is adjusted in several stages. Specifically, in the flowchart illustrated in FIG. 12, the sheet feeding device 71 reduces the suction amount by the intake duct 85 and increases the blowout amount from the exhaust duct 86 in step S104, and then returns to step S102. The passing time to the passing point is measured by the timer 109. And the process after step S103 is repeated.

  By doing so, it is possible to achieve appropriate adjustment without excessively adjusting the flow rate. An upper limit may be set for the number of adjustments and the adjustment amount.

(Fourth embodiment)
The fourth embodiment is a mode in which the air flow rate is adjusted a plurality of times in the second embodiment. In the following description, the same components as those in the first embodiment or the second embodiment are denoted by the same reference numerals, and the first embodiment and the second embodiment are referred to. Description is omitted.

  In the fourth embodiment, in the flowchart illustrated in FIG. 13, the sheet feeding device 71 reduces the suction amount by the intake duct 85 and increases the blowout amount from the exhaust duct 86 in step S203, and then step S202. Then, it is determined whether or not the double feed sensor 108 detects double feed. And the process after step S203 or S205 is repeated.

  By doing so, it is possible to achieve appropriate adjustment without excessively adjusting the flow rate. An upper limit may be set for the number of adjustments and the adjustment amount.

  The first to fourth embodiments only disclose some of the myriad examples of the present invention, and should be appropriately designed in consideration of various factors such as purpose, application, specifications, and settings. Is possible.

  For example, in the above embodiment, when there is a possibility of double feeding, an example is shown in which the initial value is adjusted to a certain amount, for example, the suction amount 50% and the blow amount 50%, and the suction amount 20% and the blow amount 80%. However, as described in the third and fourth embodiments, the adjustment amount can be set as appropriate. Further, if it is possible to control individually, only the suction amount or only the blowing amount may be adjusted.

  Furthermore, for example, when the passage time exceeds a predetermined upper limit time in the first adjustment process, the reverse adjustment of increasing the suction amount and decreasing the blowout amount may be performed.

  Further, the first to fourth embodiments can be executed not only independently but also in combination as appropriate.

  As described above in detail, the sheet feeding device 71 described in the present application includes the sheet stacking table 74 on which the sheet bundle is stacked, and the suction section (suction / exhaust fan 84 and intake duct 85) for sucking air. A sheet conveying section (sheet conveying belt 81) for sucking sheets of the sheet bundle stacked on the sheet stacking base 74 by suction of the sections (intake / exhaust fan 84, intake duct 85), and conveying the sucked sheet; And a blow-out unit (exhaust duct 86) that blows out air toward an end of the sheet in the conveyance direction, and supplies a bundle of sheets to a supply destination via a conveyance path (conveyance path 33) 71, a detection means (paper leading edge sensor 106, double feed sensor 108, timing unit 109) for detecting the conveyance status of the paper and the detection means (paper leading edge sensor 106, double feed sensor 108, timing unit 109). Depending on the detection result Characterized by comprising an adjustment means (control unit 101) for adjusting the flow rate of air.

  Therefore, the paper feeding device 71 according to the present application can suppress the occurrence of double feeding by adjusting the flow rate of air when there is a possibility that double feeding of paper has occurred.

  Further, in the sheet feeding device 71 described in the present application, the adjusting unit (control unit 101) is configured such that the suction amount by the suction unit (intake / exhaust fan 84, intake duct 85) and the blowout from the blowout unit (exhaust duct 86). It is characterized by adjusting at least one of the quantities.

  Therefore, the paper feeding device 71 according to the present application can suppress the occurrence of double feeding by optimizing the suction amount and / or the blowing amount.

  In the sheet feeding device 71 described in the present application, the detection unit detects a plurality of sheets pulled out from the sheet bundle stacked on the sheet stacking table (multifeed sensor). 108), and the adjusting means (control unit 101) adjusts the air flow rate when the multi-feed detection unit (multi-feed sensor 108) detects that a plurality of sheets have been taken out. It is characterized by.

  Therefore, the sheet feeding device 71 according to the present application can detect double feeding by the baking soda detection unit (double feeding sensor 108).

  Further, in the paper feeding device 71 described in the present application, the detection unit is a time measuring unit 109 that measures a conveyance time from the start of conveyance to a predetermined position in the conveyance path, and the adjustment unit (control unit 101) includes The air flow rate is adjusted in accordance with the transport time measured by the time measuring unit 109.

  Therefore, when the conveyance time is short, the paper feeding device 71 according to the present application can detect double feeding because there is a possibility that feeding has occurred in the previous paper conveyance.

  Further, in the sheet feeding device 71 described in the present application, the adjusting unit (control unit 101) is configured to reduce the amount of suction by the suction unit (intake / exhaust fan 84, intake duct 85) and the blowout as adjustment of the air flow rate. It is characterized in that at least one of the increase in the amount of blowout from the section (exhaust duct 86) is performed.

  Therefore, when there is a possibility of double feeding, the sheet feeding device 71 according to the present application prevents a plurality of sheets from being sucked up by suppressing the sucking amount and / or a sheet accompanying separation of individual recording sheets by increasing the blowing amount. It is possible to suppress the occurrence of double feeding by improving the bundle separation efficiency.

  The paper feeding device 71 described in the present application is a paper feeding device 71 that transports a sheet separated from a bundle of paper stacked on a paper stacking table using an air flow generated inside the device and supplies the paper to a supply destination. The detection means (paper leading edge sensor 106, double feed sensor 108, timing unit 109) for detecting the sheet conveyance status and the detection results of the detection means (paper leading edge sensor 106, double feeding sensor 108, timing unit 109) Accordingly, an adjustment means (control unit 101) for adjusting the flow rate of air is provided.

  Therefore, the paper feeding device 71 according to the present application can suppress the occurrence of double feeding by adjusting the flow rate of air when there is a possibility that double feeding of paper has occurred.

  The image forming apparatus 1 described in the present application includes the paper feeding device 71 and an image forming unit (image processing unit 104) that forms an image on a sheet supplied from the paper feeding device 71. .

  Therefore, the image forming apparatus 1 according to the present application can suppress the occurrence of double feeding by adjusting the flow rate of air when there is a possibility that double feeding of paper has occurred.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Original reading apparatus 11 Printing part 12 Paper conveyance part 13 Paper supply part 14 Large capacity paper feed cassette (LCC)
DESCRIPTION OF SYMBOLS 71 Paper feeder 72 Outer frame 73 Bottom plate 74 Paper stacking base 75 Paper drawer part 76 Paper rear end guide 77, 78 Assist duct 79, 80 Assist fan 81 Paper conveyance belt 82, 83 Roller 84 Air intake / exhaust fan 85 Air intake duct 86 Exhaust Duct 92 Pulse motor 93 Height position sensor 101 Control unit 102 Input operation unit 103 Memory 104 Image processing unit 105 Size detection unit 106 Paper leading edge sensor 108 Double feed sensor 109 Timing unit

Claims (5)

A sheet transporting unit that has a sheet stacking table for stacking a sheet bundle and a suction unit that sucks air, sucks the sheets of the sheet bundle loaded on the sheet stacking table by suction of the suction unit, and transports the sucked sheet A sheet feeding device that supplies the sheets of the sheet bundle to the supply destination via the conveyance path, and a blowout unit that blows out air toward an end portion of the sheet bundle on the conveyance direction side of the sheet,
Detection means for detecting the conveyance status of the paper;
An adjustment unit that adjusts a flow rate of air according to a detection result of the detection unit. The sheet feeding device according to claim 1,
The adjusting means includes
At least one of the suction amount by the suction portion and the blowout amount from the blowout portion is adjusted. The sheet feeding device according to claim 1 or 2,
The detection means includes
A double feed detection unit for detecting that a plurality of sheets are pulled out from a bundle of sheets loaded on the sheet loading table;
The adjusting means includes
A sheet feeding device that adjusts an air flow rate when the double feed detection unit detects that a plurality of sheets have been taken out. The paper feeding device according to any one of claims 1 to 3,
The detection means includes
A timekeeping unit that times the transport time from the start of transport to a predetermined position in the transport path;
The adjusting means includes
The sheet feeding device, wherein the flow rate of air is adjusted according to the conveyance time measured by the time measuring unit. A paper feeding device according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet supplied from the sheet feeding device.

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