JP2011246204A - Paper feeder and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeder capable of coping with various paper sheets, and capable of surely feeding the paper sheets one by one particularly when feeding the paper at a high speed, and an image forming system having the paper feeder.SOLUTION: This paper feeder includes a paper sheet placing tray for stacking the paper sheets, a feeding mechanism part for carrying the paper sheets stacked on the paper sheet placing tray to a carrying passage, an air-blowing part arranged on the side end part side of the paper sheets, an upper surface pressing member positioned above the air-blowing part and displaceable to a first position for pressing a paper sheet side end part upper surface by predetermined pressing force and a second position moved in the paper sheet upper surface direction than the first position, a switching mechanism part for switching an upper surface pressing member to the first position and the second position, and a control part for controlling the switching mechanism part for displacing the upper surface pressing member to the second position before starting or simultaneously when starting paper sheet carrying operation of the feeding mechanism part when blowing air by the air-blowing part.

Description

  The present invention relates to a sheet feeding device that separates and feeds a bundle of sheets stacked on a sheet loading table one by one, and an image forming system having the sheet feeding device.

  2. Description of the Related Art Conventionally, as a sheet feeding device that supplies sheets one by one to an image forming unit of an image forming apparatus such as a copying machine or a printer, an air assist type that blows air from the side of the sheet and floats the sheet is widely used. .

  In recent years, there has been a growing demand for a paper feeding apparatus that can accurately separate and feed a wide variety of paper, for example, coated paper or thick paper to thin paper one by one.

  For example, coated paper increases the adhesion between papers in a high humidity environment, and when the paper is blown from the side and floats, multiple papers may come into close contact and form a bundle. So it becomes double feed. Further, when the thick paper has a stiffness such as curling, for example, in the lower curl position, the air blown from the side escapes to other than between the papers, and the wind pressure of the blown air is lowered, making it difficult to float the paper. In the case of the upper curl position, the air is excessively levitated by the air blow from the side surface, resulting in double feeding. In order to cope with such a problem, it has an abutting member that abuts on the uppermost surface of the paper, a follow-up means that abuts the abutting member following the floating of the paper, and a shielding member that shields the air outlet, A device that changes the relative position of the shielding member with respect to the air blowing port in conjunction with the movement of the contact member is known (see, for example, Patent Document 1).

  Further, the detection means for detecting the uppermost height of the sheet, the relative position variable means for relatively changing the air blowing position of the blower means and the uppermost height of the sheet, and the relative position based on the detection result of the detection means. 2. Description of the Related Art A sheet supply apparatus including a control unit that controls driving of a position variable unit is known (see, for example, Patent Document 2).

JP 2005-35690 A JP 2007-91363 A

  The paper feeding device described in Patent Document 1 shields the space above the paper at the blower opening, and the abutting member presses the paper bundle, so that air can be efficiently blown between the papers, which is effective for floating the paper. There is something. However, since the abutting member is in contact with and pressed against the paper even during the feeding operation, it becomes a load at the time of feeding the paper, and a fold mark by the abutting member may rarely occur when the paper is thin.

  In addition, the sheet feeding apparatus described in Patent Document 2 is difficult to lift the uppermost sheet, particularly in the case of thick paper, and a large gap is formed between the uppermost sheet and the second sheet, and particularly high-speed feeding. When paper is fed, there is a problem that after feeding the uppermost paper, the next paper cannot be lifted in a short time and paper feed is delayed or not fed.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a sheet feeding device that can handle a wide variety of sheets, and that can reliably feed one sheet at a time even when feeding at high speed, and an image forming system having the sheet feeding device. It is intended.

  The above object is achieved by the following configuration.

  (1) A paper mounting table for stacking paper, a feeding mechanism unit for transporting the paper stacked on the paper mounting table to a transport path, a blower unit disposed on the side edge side of the paper, and the blower unit Is an upper surface pressing member that is displaceable between a first position that presses the upper surface of the paper side end portion with a predetermined pressing force and a second position that moves in the direction of the upper surface of the paper from the first position. And a switching mechanism that switches the upper surface pressing member between the first position and the second position, and during blowing by the blowing unit, before or simultaneously with the start of the sheet conveying operation of the feeding mechanism unit And a control unit that controls the switching mechanism unit to displace the upper surface pressing member to the second position.

  (2) The feeding mechanism unit includes a belt having a plurality of through holes and an air suction unit that is located inside the belt and sucks air through the through holes. A suction conveyance device that sucks air to adsorb a sheet to the belt and conveys the sheet to a conveyance path, and the start of the sheet conveyance operation of the feeding mechanism unit is the start of driving of a driving roller that drives the belt. The sheet feeding device according to (1), characterized in that:

  (3) A conveyance roller and a detection member for detecting a sheet on the downstream side of the conveyance roller are provided on the downstream side of the feeding mechanism, and the control unit is simultaneously with or after the detection of the leading edge of the sheet of the detection member. The sheet feeding device according to (2), wherein the switching mechanism unit is controlled to displace the upper surface pressing member to the first position.

  (4) The feeding mechanism is transported to a transport path by a feed roller disposed on the upper surface of the sheet, a separation roller for separating the sheet into one sheet, and a transport roller disposed on the downstream side of the separation roller. The sheet feeding device according to (1) is characterized in that the operation of conveying the sheet by the feeding mechanism unit is the start of driving of a roller disposed on the upper surface of the sheet.

  (5) It has a detection member for detecting a sheet on the downstream side of the transport roller, and the control unit moves the upper surface pressing member to the first position simultaneously with or after the detection of the leading edge of the sheet of the detection member. The sheet feeding device according to (4), wherein the switching mechanism unit is controlled to be displaced.

  (6) The air pressure of the air blowing section is 260 Pa to 320 Pa, and the pressing force on the paper when the upper surface pressing member is in the first position is 0.4 N to 2.4 N. The sheet feeding device according to any one of (1) to (5).

  (7) The wind pressure of the air blowing unit is 260 Pa to 380 Pa, and the pressing force against the sheet when the upper surface pressing member is in the first position is 0.4 N to 1.2 N. The sheet feeding device according to any one of (1) to (5).

  (8) An image forming system comprising: the paper feeding device according to any one of (1) to (7); and an image forming device that forms an image on a sheet supplied from the paper feeding device. .

  According to the present invention, it is possible to provide a sheet feeding device that can handle a wide variety of sheets, and that can reliably feed one sheet at a time even when feeding at high speed, and an image forming system having the sheet feeding device. It becomes.

1 is an overall configuration diagram of an image forming system including an image forming apparatus, an image reading apparatus, an automatic document feeder, and a large-capacity paper feeder. FIG. 3 is a perspective view illustrating a main part of the sheet feeding device main body according to the first embodiment. 1 is a schematic cross-sectional view of a sheet feeding device main body according to a first embodiment. It is a schematic diagram which shows an example of a 1st ventilation part. FIG. 3 is a block diagram illustrating a control configuration of a sheet feeding device according to a first embodiment. 4 is a flowchart illustrating an outline of operation of the sheet feeding device according to the first embodiment. It is a figure which shows the positional relationship of a sheet bundle and a collar part. FIG. 6 is a schematic cross-sectional view of a main part of a sheet feeding device body according to a second embodiment. 10 is a flowchart illustrating an outline of operation of a sheet feeding device according to a second embodiment.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

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

[Image forming apparatus]
FIG. 1 is an overall configuration diagram of an image forming system including an image forming apparatus A, an image reading apparatus SC, an automatic document feeder DF, and a large capacity sheet feeding apparatus LT.

  The illustrated image forming apparatus A includes an image forming unit including a photosensitive member (image carrier) 1, a charging unit 2, an image exposing unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and the like, a fixing unit 7 and And a paper transport system.

  The paper transport system includes a paper feed cassette 10, a first paper feed means 11, a second paper feed means 12, a paper discharge means 14, a transport path switching means 15, a circulation refeed means 16, a reverse paper discharge means 17, and the like. Has been.

  The document d placed on the document table of the automatic document feeder DF is conveyed, an image on one or both sides of the document is read by the optical system of the image reading device SC, and is read by the image sensor CCD. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like by the image processing unit of the control unit 20 and then sent to the image exposure apparatus 3. .

  In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  In the image forming unit, a charge is added to the photosensitive member 1 by the charging unit 2, an electrostatic latent image is formed by laser light irradiation from the image exposure device 3, and the electrostatic latent image is visualized by the developing device 4. Into a toner image. Next, the paper P stored in the paper feed cassette 10 is conveyed from the first paper feed means 11. On the other hand, the transfer residual toner on the photosensitive member 1 is removed by the cleaning unit 6.

  The sheet P is supplied from the large-capacity sheet feeding device LT or the sheet feeding cassette 10 and is conveyed in synchronization with the toner image by the second sheet feeding unit 12 including registration rollers. Thereafter, the paper P is fixed by the fixing device 7 after the toner image is transferred by the transfer means 5. The paper P after fixing is discharged out of the apparatus by the paper discharge means 14.

  In the case of double-sided copying, the paper P on which the image is formed on the first side is sent to the circulation refeed unit 16 and reversed, and after the image is formed again on the second side in the image forming unit, the paper discharge unit 14 is formed. Is discharged out of the apparatus. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is switched back by the reverse paper discharge means 17 and turned upside down, and then discharged from the apparatus by the paper discharge means 14.

[Paper Feeder]
(First embodiment)
The large-capacity paper feeding device LT connected to the image forming apparatus A has a plurality of paper feeding device bodies 30 inside, accommodates a large amount of paper, and feeds the paper to the image forming apparatus A one by one. .

  The sheet feeder main body 30 according to the first embodiment includes a sheet placing table 31, a sheet leading edge regulating member 32, a sheet trailing edge regulating member 33, and a guide rail 34. In this example, the sheet placing table 31 is configured in three stages, and each sheet placing table 31 is configured to be drawable from the large-capacity sheet feeding device LT by the guide rail 34. For example, the large-capacity paper feeder LT can accommodate 1300 sheets in the first tray, 1850 sheets in the second and third trays, and can accommodate approximately 5000 sheets as a whole.

  FIG. 2 is a perspective view illustrating a main part of the sheet feeder main body 30 according to the first embodiment, and FIG. 3 is a schematic cross-sectional view of the sheet feeder main body 30 according to the first embodiment. 2 and 3 are examples in which a suction conveyance unit that adsorbs a sheet to a belt and conveys the sheet to the conveyance path is used as a feeding mechanism unit that conveys the sheet loaded on the sheet placing table to the conveyance path. In FIG. 2, the feeding mechanism unit is shown in a temporary position slightly moved to the downstream side in the paper transport direction from the position where it is actually installed in the paper feeding device body 30.

  As shown in FIGS. 2 and 3, the sheet bundle Ps is placed on the sheet placing table 31 and is housed together with the sheet placing table 31 by a not-shown sheet placing table moving mechanism. When transporting the paper, the paper placement sensor 31 is raised until the paper height sensor PS3 shown in FIG. 3 detects that the uppermost paper P1 has reached a predetermined height.

  The pair of paper side end regulating portions 41 regulates the paper bundle Ps on the side surface in the direction orthogonal to the paper transport direction. The sheet-side end regulating member 41 can freely change the relative distance in the sheet width direction, and regulates the position of the sheet bundle Ps in the width direction corresponding to the sheet size.

  An opening 41k is formed in the pair of sheet side end regulating members 41, and air is supplied to the upper region of the sheet bundle Ps stacked from the side perpendicular to the feeding direction of the uppermost sheet P1 from the opening 41k. The 1st ventilation part 40 to spray is arrange | positioned at both side surfaces, respectively.

  In addition, a second air blowing unit 50 serving as a sheet separating unit is disposed on the downstream side of the sheet placing table 31 in the sheet feeding direction.

  Further, on the exit side of the large capacity sheet feeding device LT, a pair of transport rollers 39 for transporting the sheet transported by the suction transport device 60, which is the feeding mechanism unit of the first embodiment, to the image forming apparatus A, and its On the downstream side, a paper detection sensor PS1 that detects the presence or absence of a paper to be conveyed is disposed.

  In addition, a second blower unit 50 is disposed at the lower part of the sheet feeding direction of the suction conveyance device 60 that is the feeding mechanism unit of the first embodiment.

(First air blower)
FIG. 4 is a schematic diagram illustrating an example of the first blower 40.

  Fig.4 (a) is the front view which looked at the 1st ventilation part 40 from the ventilation port 44 side. The first blower unit 40 includes a blower unit 45 in which a blower port 44 is formed, and a fan unit 42 for blowing air below the blower port 44. The fan unit 42 is fixed to the paper side end regulating member 41, and the blower unit 45 is slidable in the vertical direction, which is the paper stacking direction, with respect to the fan unit 42. Further, as shown in FIG. 2, the upper surface of the blower unit 45 is formed with a collar portion 47 that protrudes toward the sheet bundle Ps in a bowl-like shape above the sheet, and when the sheet placement table 31 is raised. The uppermost sheet P1 is brought into contact with and pressed against the upper surface of the side end portion. That is, the collar portion 47 functions as an upper surface pressing member. Moreover, the wire 46 is connected with the ventilation part unit 45, and the plunger of solenoid SL is connected with the other end part of the wire 46 (refer FIG. 2).

  FIG. 4B is a view showing the back side of the first blower 40. On the back side of the first blower unit 40, a spring 43 is hung between a pin 42p formed on the fan unit 42 and a pin 45p formed on the blower unit 45. The air blowing unit 45 is pulled in the direction of the fan unit 42 by the urging force of the spring 43. For this reason, when the paper mounting table 31 is raised to a predetermined height, the collar portion 47 comes into contact with the upper surface of the uppermost paper P1 and reaches a position where the air outlet 44 shown in FIGS. 4 (a) and 4 (b) is exposed. The pressure rises and a pressing force is applied to the sheet bundle Ps by the spring 43.

  If the pressing force is too weak, the flange 47, which is the upper surface pressing member, is pushed up only by the wind pressure of the fan, and the pressing force cannot be exerted on the upper surface side edge of the sheet. On the other hand, if the pressing force is too strong, the state where the sheet is sufficiently lifted is further pressed to cause the sheets to be pressure-bonded, causing double feed.

  For this reason, when the wind pressure of the 1st ventilation part 40 is 260 Pa-320 Pa, when the paper mounting base 31 raises to predetermined | prescribed height, the pressing force (per one side) with respect to the paper of the collar part 47 is 0.4 N or more, It is preferable that it is 2.4N or less.

Moreover, in the paper feeder corresponding to the paper having a basis weight of 350 g / m ² or less, the wind pressure of the first air blowing unit 40 is set to 260 Pa to 380 Pa, and the pressing force (per one side) of the flange portion 47 is 0.4 N or more. It is preferable to be 1.2 N or less.

  FIG. 4C shows a state in which the solenoid SL (see FIG. 2) connected to the other end of the wire 46 is operated. When the solenoid SL is operated, the plunger is attracted by the electromagnet, and the blower unit 45 is moved upward against the urging force of the spring 43 as shown in the figure.

  The position of H1 shown in FIG. 4 indicates the height of the uppermost sheet P1 when the uppermost part of the sheet bundle is detected by the sheet height sensor PS3 (see FIG. 3) and the sheet placing table 31 is stopped. In this state, the sheet bundle Ps is being pressed by the flange 47.

  That is, the flange portion 47 which is an upper surface pressing member has a first position (height of H1 in the drawing) that presses the upper surface of the sheet side end portion, and a second position (the height of the sheet H1 in the drawing). It can be displaced to a height of H2 in the drawing. In addition, this displacement is performed by a switching mechanism portion composed of a solenoid SL and a spring 43.

  In addition, the 1st ventilation part 40 may change a wind pressure according to the kind of paper.

  Further, in this example, the member corresponding to the upper surface pressing member is described as an example in which the blower unit 45 is integrally formed as the flange portion 47. However, the present invention is not limited to this and is different from the blower unit 45. It may be formed of a body. The mechanism for pressing and displacing the upper surface pressing member is not limited to this, and any mechanism that can apply a predetermined pressing force at the first position and can be displaced to the second position may be used. For example, a method may be employed in which displacement is performed by motor drive and the pressing force at the first position is limited by a torque limiter.

(Feeding mechanism)
As shown in FIGS. 2 and 3, the suction conveyance device 60 that is the feeding mechanism unit of the first embodiment is located above the sheet bundle Ps stacked on the sheet loading table 31 and arranged downstream in the sheet conveyance direction. It is installed.

  The suction conveyance device 60 is disposed inside one end of an endless belt 63 (hereinafter, referred to as suction belt) in which a large number of small-diameter through holes are formed, and a driving force is supplied to the suction belt 63 by a motor (not shown). The first roller 61 and the second roller 62 that is arranged on the inner side of the other end of the suction belt 63 and is driven to rotate (in this example, two small-diameter rollers are used. May be).

  An air suction part 64 that sucks air through the through hole is disposed inside the suction belt 63. The air suction unit 64 includes a suction duct and a suction fan disposed in the suction duct, and the air sucked by the suction fan is discharged to the side through the suction duct.

  The uppermost sheet P1 sucked by the suction belt 63 by the suction of the air suction unit 64 is transported to the transport path 70 by the rotation of the first roller 61 and the second roller 62.

(Second air blower)
The fan unit 51 of the second air blowing unit 50 is attached with the air blowing port 53 facing upward. The air blown upward is changed in direction by the guide plate 52, blown obliquely upward from the air blowing port 53, and blown to the vicinity of the suction belt 63 of the suction conveyance device 60.

  The driving of the second blower 50 is controlled according to the type of paper. In other words, OHP film, trace paper, coated paper with a smooth surface, paper with perforations and lines, etc., and dust printed on offset printed paper. To ensure separation.

  The above is the schematic mechanism of the paper feeding device according to the first embodiment.

  FIG. 5 is a block diagram illustrating a control configuration of the sheet feeding device according to the first embodiment. In FIG. 4, components other than the components according to the present invention are omitted.

  The operation of the control unit 70 of the large capacity sheet feeding device LT is controlled in cooperation with the control unit 20 of the image forming apparatus A. The control unit 70 of the large-capacity sheet feeding device LT includes a suction conveyance device 60 that is a feeding mechanism unit according to the first embodiment, a first blowing unit 40, a second blowing unit 50, and a solenoid SL that is an actuator of a switching mechanism unit. Also, the operation of the sheet mounting table moving mechanism is controlled. The control unit 70 is input with detection results of the paper height sensor PS3 and the paper detection sensor PS1, paper size, paper type, and the like.

  FIG. 6 is a flowchart illustrating an outline of the operation of the sheet feeding device according to the first embodiment. Hereinafter, an outline of the operation of the sheet feeding device according to the first embodiment will be described according to a flow. In the flow shown in FIG. 6, the sheet placing table 31 has already been raised, and the uppermost sheet P1 of the sheet bundle Ps is positioned at a predetermined height by the sheet height sensor PS3 (see FIG. 3) ( The 1st ventilation part shall be in the state shown to FIG. 4 (a), (b).

  When the start of the image forming operation is instructed by the operator, the first air blowing unit 40 and the second air blowing unit 50 are driven in cooperation with the image forming unit of the image forming apparatus A to start the air blowing. Suction is started (step S101). At this time, the solenoid SL, which is an actuator of the switching mechanism, is turned off, and the flange portion 47, which is an upper surface pressing member, is in a state of pressing the upper surface of the uppermost sheet side end portion at the first position.

  FIG. 7 is a diagram illustrating a positional relationship between the sheet bundle Ps and the collar portion 47.

  When the sheet placing table 31 is raised and the uppermost sheet P1 of the sheet bundle Ps is positioned at a predetermined height by the sheet height sensor PS3 (see FIG. 3) and no air is blown, FIG. As shown in (), the pressed state against the paper is maintained.

  By the operation in step S101, as shown in FIG. 7B, the upper sheet of the sheet bundle Ps is separated by the air blown by the first air blower 40 and the second air blower 50, and the suction is carried out by the suction conveyance device 60. The upper sheet P1 is sucked onto the suction belt 63.

  At this time, the flange portion 47, which is the upper surface pressing member, maintains a pressing state against the uppermost sheet P1 by the urging force of the spring 43, and the levitation force and the pressing force due to the levitation of the end of the sheet due to the air blow are balanced. It will be a position to keep. In this way, until the uppermost sheet P1 is adsorbed by the adsorption belt 63, the pressed state against the sheet is maintained, so that the air flow is prevented from escaping above the uppermost sheet P1. Air can be efficiently blown between sheets below the upper sheet P1, and separation of sheets can be improved regardless of the type of sheet.

  Returning to FIG. 6, the solenoid SL, which is the actuator of the switching mechanism, is then turned on at a predetermined timing, and the flange 47, which is the upper surface pressing member, is lifted upward and displaced to the second position (step S102). As a result, the pressure on the uppermost sheet P1 is released.

  FIG.7 (c) has shown the state which raised the collar part 47 upward and was displaced to the 2nd position.

  Returning to FIG. 6, the paper transport operation is then started (step S103). In the first embodiment, the start of the paper transport operation corresponds to the rotation of the paper feed roller, that is, the rotation of the first roller 61 that supplies driving force to the suction belt 63.

  When the sheet transport operation is started, the flange 47 as the upper surface pressing member is in the second position, so that friction with the uppermost sheet P1 is reduced and the sheet can be transported more smoothly. .

  Note that the operation of displacing the collar portion 47, which is the upper surface pressing member in step S102, to the second position and the start of the paper transport operation in step S103 may be performed simultaneously.

  Returning to FIG. 6, next, it waits for the paper detection sensor PS1 to detect the leading edge of the paper being conveyed (step S104). When the leading edge of the sheet being conveyed is detected by the sheet detection sensor PS1 (step S104; Yes), the rotation of the sheet feeding roller is stopped (step S105), the solenoid SL that is the actuator of the switching mechanism is turned off, and the spring 43 The urging force is applied to the flange 47 (step S106). Thereby, the pressing state with respect to the sheet | seat by the collar part 47 is restarted. The restart of the pressed state may be performed at the same time as or after the detection of the leading edge of the paper by the paper detection sensor PS1.

  When the sheet detection sensor PS1 detects the leading edge of the sheet being conveyed, it means that the uppermost sheet P1 is being conveyed by the conveyance roller pair 39, and the sheet 47 is pressed against the sheet. Will not interfere with transport.

  Next, it is determined whether or not the uppermost sheet P1 has completely separated from the sheet bundle Ps (step S107). This determination may be made by determining that the sheet detection sensor PS1 has separated from the detection of the trailing edge of the sheet, or may have determined that the sheet has been separated from the passage of time calculated from the sheet size and the conveyance speed. Further, a sensor for detecting the trailing edge of the sheet may be disposed between the suction conveyance device 60 and the conveying roller pair 39 shown in FIG.

  If it is determined that the uppermost sheet P1 has completely separated from the sheet bundle Ps (step S107; Yes), it is determined whether or not the designated number of sheets has been fed (step S108). If the specified number of sheets has not been fed (step S108; No), the process returns to step S102 and the above operation is repeated.

  When the specified number of sheets has been fed (step S108; Yes), driving such as blowing and suction is stopped and the process is terminated.

  In addition, as a timing for displacing the flange portion 47 that is the upper surface pressing member to the second position before the start of the sheet transport operation, for example, when transporting the first sheet, a predetermined time is used as a timer. Or the like, and the sheet is moved to the second position before the start of the sheet transport operation. For the second and subsequent sheets, the sheet is detected at the same time as or detected by the sheet detection sensor PS1. What is necessary is just to displace to a 2nd position before the start of conveyance operation | movement.

  The predetermined time for the first sheet is, for example, a processing speed of about 80 sheets / minute, where t is the time from the displacement of the collar 47 to the second position to the start of the sheet conveying operation. In this case, 0 <t ≦ 300 (mS) is preferable. Note that t is not limited to this range, and is determined according to the speed of the image forming unit of the image forming apparatus and the conveyance speed of the paper feeding device. Also, this time t may be applied to the conveyance of the second and subsequent sheets.

  The above is the outline of the operation of the sheet feeding device according to the first embodiment.

  As described above, when the sheet before sheet conveyance is floated, the upper surface pressing member is pressed to prevent the air blown by the first air blowing unit from escaping from above the uppermost sheet, so that coated paper, cardboard, etc. This makes it possible to reliably separate and transport heavy sheets of paper.

  Furthermore, at the same time as or before the start of the paper transport operation of the feeding mechanism, the upper surface pressing member is retracted upward to release the pressure, eliminating friction with the paper being transported, especially for thin paper The generation of fold marks due to the upper surface pressing member can be eliminated.

  In the first embodiment, an example in which the suction conveyance device is applied to the feeding mechanism unit has been described. However, the present invention can also be applied to a configuration in which the feeding mechanism unit is configured by a roller. Below, the example which comprised the feeding mechanism part with the roller is demonstrated as 2nd Embodiment.

(Second Embodiment)
FIG. 8 is a schematic cross-sectional view of a main part of the sheet feeder main body 30 according to the second embodiment. FIG. 8 illustrates the case where the collar portion 47 is in the first position. The feeding mechanism according to the second embodiment is conveyed by a feeding roller disposed on the upper surface of the sheet, a separating roller that separates the sheet into one sheet, and a conveying roller disposed on the downstream side of the separating roller. It is to be transported to the route.

  In FIG. 8, the stacked paper bundle Ps is placed on a paper placement table (not shown) and supported by a paper placement table moving mechanism so as to be moved up and down.

  As in the first embodiment, the pair of paper side end regulating portions 41 are arranged on the side surface in the direction orthogonal to the paper transport direction. The sheet-side end regulating member 41 can freely change the relative distance in the sheet width direction, and regulates the position of the sheet bundle Ps in the width direction corresponding to the sheet size.

  An opening 41k is formed in the pair of sheet side end regulating members 41, and air is supplied to the upper region of the sheet bundle Ps stacked from the side perpendicular to the feeding direction of the uppermost sheet P1 from the opening 41k. The 1st ventilation part 40 to spray is arrange | positioned at both side surfaces, respectively. The structure of the 1st ventilation part 40 is the same as that of 1st Embodiment, and has the air blower unit 45 in which the ventilation opening 44 was formed, and the fan unit 42 for ventilation below the ventilation opening 44. . The fan unit 42 is fixed to the paper side end regulating member 41, and the blower unit 45 is slidable in the vertical direction, which is the paper stacking direction, with respect to the fan unit 42. Further, the upper surface of the blower unit 45 is formed with a flange portion 47 that protrudes toward the sheet bundle Ps in a bowl shape above the sheet, and when the sheet loading table 31 is raised, the uppermost sheet P1 Abuts and presses the upper surface of the side end. A wire 46 is connected to the blower unit 45, and a plunger of a solenoid SL is connected to the other end of the wire 46.

  A feeding roller 81 is disposed at the leading end of the uppermost paper P1 in the feeding direction. The upper roller 82 separates the uppermost paper P1 that is rotated in the direction of the arrow and floated by the blower of the first blower 40. And sent between the separation lower rollers 83.

  When a plurality of sheets are fed between the separation upper roller 82 and the separation lower roller 83 by the feeding roller 81, the second and subsequent sheets are pushed back by the separation lower roller 83, and only the uppermost sheet is separated. It passes between the roller 82 and the lower separation roller 83 and is sent to the image forming unit by the conveying roller pair 39 on the downstream side. A sheet detection sensor PS1 that detects the presence or absence of a sheet to be transported is disposed on the downstream side of the transport roller pair 39.

  Also in the second embodiment having such a configuration, when the wind pressure of the first air blowing unit 40 is 260 Pa to 320 Pa, the pressing force of the flange 47 against the sheet when the sheet placing table 31 rises to a predetermined height ( (Per one side) is preferably 0.4N or more and 2.4N or less.

Moreover, in the paper feeder corresponding to the paper having a basis weight of 350 g / m ² or less, the wind pressure of the first air blowing unit 40 is set to 260 Pa to 380 Pa, and the pressing force (per one side) of the flange portion 47 is 0.4 N or more. It is preferable to be 1.2 N or less.

  The block diagram in the case of the paper feeding device according to the second embodiment is that the suction conveyance device shown in FIG. 5 is conveyed to the conveyance path by each roller shown in FIG. 8, and the second air blowing unit is omitted. Become.

  FIG. 9 is a flowchart illustrating an outline of the operation of the sheet feeding device according to the second embodiment. The flow shown in FIG. 9 is different from the flow shown in FIG. 6 in steps S101 to S103. For this reason, only different steps S201 to S203 in the flow shown in FIG. 9 will be described.

  In the flow shown in FIG. 9, when the operator instructs the start of the image forming operation, the first air blowing unit 40 is driven in cooperation with the image forming unit of the image forming apparatus A to start air blowing (step S201). At this time, the solenoid SL, which is an actuator of the switching mechanism, is turned off, and the flange portion 47, which is an upper surface pressing member, is in a state of pressing the upper surface of the uppermost sheet side end portion at the first position.

  Next, the solenoid SL, which is an actuator of the switching mechanism, is turned on at a predetermined timing, and the flange portion 47, which is an upper surface pressing member, is lifted upward and displaced to the second position (step S202). As a result, the pressure on the uppermost sheet P1 is released.

  Next, the paper transport operation is started (step S203). In the second embodiment, the start of the sheet conveying operation corresponds to the rotation of the sheet feeding roller, that is, the rotation of the feeding roller 81 disposed at the leading end on the uppermost sheet P1.

  When the sheet transport operation is started, the flange 47 as the upper surface pressing member is in the second position, so that friction with the uppermost sheet P1 is reduced and the sheet can be transported more smoothly. .

  Note that the operation of displacing the collar portion 47, which is the upper surface pressing member in step S202, to the second position and the start of the sheet conveying operation in step S203 may be performed simultaneously.

  Also in the second embodiment, the timing for displacing the flange 47, which is the upper surface pressing member, to the second position is the same as that described in the first embodiment.

  The subsequent steps are the same as those after step S104 shown in FIG.

  That is, as in the second embodiment, a feeding roller having a feeding mechanism portion disposed on the upper surface of a sheet, a separating roller for separating the sheet into one sheet, and a conveying roller disposed on the downstream side of the separating roller The same effect as that of the first embodiment can be obtained even in the sheet feeding device configured as described above.

  An appropriate pressing force with respect to the sheet when the flange portion 47 that is the upper surface pressing member is in the first position will be described based on an embodiment.

  A paper side end regulating member 41 shown in FIG. 2 and a first air blowing unit 40 shown in FIG. 4 were assembled to the product A, and a paper passing test was conducted.

Test conditions are
・ Environment: High temperature and high humidity (temperature 30 ° C, humidity 80%)
-Paper type: high-quality paper (basis weight 350 g / m ² )
-Paper size: 330mm width x 482mm length
・ Bridge: Two places on both sides ・ Pressing force: 0.1N, 0.2N, 0.4N, 0.8N, 1.2N, 2.4N, 3N
(Pressing force per side of the buttocks)
・ Wind pressure (per one side of the first blower): 220 Pa, 260 Pa, 320 Pa, 380 Pa
Feeding mechanism: suction conveyance / number of sheets passed: 500 sheets each.

  In the evaluation, ○ was passed without any problem, △ when the defect occurred once, and × when the defect occurred twice or more. The results are shown in the following (Table 1).

  * 1 in the table indicates the occurrence of no feed. This is presumed that the wind pressure was not applied to the gap between the sheet bundles and the sheets could not be separated from each other.

  * 2 in the table indicates the occurrence of carry-on. This is presumably because an excessive wind pressure is applied to the sheet bundle, and the sheets are rubbed strongly at the time of feeding.

  In the experiment, a paper type with a large basis weight was used in a high-temperature and high-humidity environment, and severe conditions were set in which the paper absorbs moisture and easily causes poor feeding due to insufficient floating. For this reason, if there is no problem under these conditions, it can be said that there is no problem with a paper type having a small basis weight.

  From the above results, it is understood that when the wind pressure is 260 Pa to 320 Pa, the pressing force (per one side) of 0.4 N to 2.4 N is appropriate. Moreover, when wind pressure is 260 Pa-380 Pa, it turns out that the pressing force (per one side) of 0.4N-1.2N is appropriate.

DESCRIPTION OF SYMBOLS 30 Paper feeder main body 31 Paper mounting base 39 Conveyance roller pair 40 1st ventilation part 41 Paper side edge control member 41k Opening part 42 Fan unit 43 Spring 44, 53 Blower port 45 Blower part unit 46 Wire 47 Gutter part (Upper surface pressing member) )
50 Second blower 60 Adsorption conveyance device 63 Endless belt (adsorption belt)
64 Air Suction Unit A Image Forming Device DF Automatic Document Feeder LT Large Capacity Feeder SC Image Reader SL Solenoid Ps Paper Bundle P1 Topmost Paper PS1 Paper Detection Sensor PS3 Paper Height Sensor

Claims (8)

A paper mounting table for loading paper;
A feeding mechanism that transports the paper loaded on the paper mounting table to a transport path;
A blower disposed on the side edge of the paper;
Displaceable between a first position that is located above the blower and presses the upper surface of the sheet side end portion with a predetermined pressing force, and a second position that moves in the direction of the upper surface of the sheet from the first position. An upper surface pressing member;
A switching mechanism for switching the upper surface pressing member between the first position and the second position;
A controller that controls the switching mechanism so as to displace the upper surface pressing member to the second position while the air is being blown by the blower and before or simultaneously with the start of the sheet transport operation of the feeding mechanism. And a paper feeding device. The feeding mechanism section includes a belt having a plurality of through holes and an air suction section that is located inside the belt and sucks air through the through holes, and sucks air by the air suction section. A suction conveyance device that adsorbs the paper to the belt and conveys the paper to a conveyance path,
The sheet feeding device according to claim 1, wherein the sheet conveying operation of the feeding mechanism unit is started by driving of a driving roller that drives the belt. A transport roller on the downstream side of the feeding mechanism and a detection member for detecting paper on the downstream side of the transport roller;
The control unit controls the switching mechanism so as to displace the upper surface pressing member to the first position simultaneously with or after detection of the leading edge of the sheet of the detection member. Paper feeder. The feeding mechanism portion is transported to a transport path by a feed roller disposed on the upper surface of the sheet, a separation roller for separating the sheet into one sheet, and a transport roller disposed on the downstream side of the separation roller. Yes,
The sheet feeding device according to claim 1, wherein the start of the sheet feeding operation of the feeding mechanism unit is a start of driving of a roller disposed on the upper surface of the sheet. A detection member for detecting paper on the downstream side of the transport roller;
The said control part controls the said switching mechanism part to displace the said upper surface pressing member to the said 1st position simultaneously with the detection of the front-end | tip of the paper of the said detection member, or after that. Paper feeder. The wind pressure of the air blowing part is 260 Pa to 320 Pa,
The sheet feeding according to any one of claims 1 to 5, wherein a pressing force to the sheet when the upper surface pressing member is in the first position is 0.4N to 2.4N. apparatus. The wind pressure of the blowing section is 260 Pa to 380 Pa,
The sheet feeding according to any one of claims 1 to 5, wherein a pressing force with respect to the sheet when the upper surface pressing member is at the first position is 0.4N to 1.2N. apparatus.   8. An image forming system comprising: the sheet feeding device according to claim 1; and an image forming apparatus that forms an image on a sheet supplied from the sheet feeding device.

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