JP2019094212A - Sheet feeding device, image formation device, and image formation system - Google Patents

Abstract

To provide a sheet feeding device which enables prevention of feeding failures.SOLUTION: A sheet feeding device 200 which floats and feeds a sheet on the top from a bundle of sheets P loaded on a sheet loading mount 11 by blowing air from air blowing means such as an air blowing device 24 to the bundle of the sheets and feeds the sheet by feeding means such as a feeding unit 20. It is equipped with air sucking means such as a downward air sucking device 25 which sucks air so that a force acts toward a direction for sheets nearby the topmost sheet to draw away from the feeding means, and the air sucking means consists of a sucking nozzle 25a which sucks air, a sucking fan such as a downward sucking fan 42 which generates negative pressures, and a sucking duct such as a downward air sucking chamber 33 which allows air flow between the sucking nozzle and the sucking fan, and is equipped with an opening/shutting mechanism such as a downward sucking shutter 34 which opens/shuts the air flow in the sucking duct.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet feeding apparatus, an image forming apparatus, and an image forming system.

2. Description of the Related Art Conventionally, there is known a sheet feeding apparatus which blows air to a sheet bundle stacked on a sheet stacking table to feed an uppermost sheet while separating the uppermost sheet from the sheet bundle.
As a sheet feeding apparatus of this type, according to Patent Document 1, air is blown to a sheet bundle to float the uppermost sheet, and the uppermost sheet is attracted to the belt surface of a suction belt as a feeding unit facing the uppermost sheet. An apparatus for feeding is described. In this apparatus, when air is blown to the sheet bundle, the sheet in the vicinity of the uppermost sheet is suppressed in order to suppress that another sheet is adsorbed to the suction belt together with the uppermost sheet and the double feeding occurs. There is provided a suction nozzle for applying a suction force directed downward with respect to. When another sheet is adsorbed to the suction belt together with the uppermost sheet, the air blown to the sheet bundle acts to press the other sheet to the suction belt side (uppermost sheet side). According to Patent Document 1, the air suction of the suction nozzle cancels the action of the blowing air which presses the other sheet to the suction belt side (uppermost sheet side), and the top sheet adsorbed to the suction belt is the other sheet. It is said that the sheets can be separated to suppress double feeding.

  However, in the sheet feeding apparatus of Patent Document 1, air suction can not be shut off when air suction is unnecessary.

  In order to solve the problems described above, according to the present invention, air is blown to the sheet bundle stacked on the sheet loading table by the air blowing means, and the uppermost sheet is floated from the sheet bundle and fed by the feeding means. The sheet feeding apparatus further includes an air suction unit that sucks air so that a force acting in a direction away from the feeding unit acts on the sheet in the vicinity of the uppermost sheet, and the air suction unit sucks the air. And a suction duct for ventilating between the suction nozzle and the suction fan, and an opening / closing mechanism for blocking and opening the ventilation in the suction duct. It is characterized by

  According to the present invention, there is an excellent effect that air suction can be shut off when air suction is unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the image forming system of this embodiment. FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view of a sheet feeding apparatus of the present embodiment provided on the side surface of the apparatus main body. FIG. 2 is a schematic side view of the sheet feeding device of the present embodiment. FIG. 2 is a schematic front view of the sheet feeding device of the present embodiment. FIG. 1 is a schematic perspective view of a sheet feeding device of the present embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The schematic perspective view of an air blower and a downward suction apparatus. The perspective view seen from the front side of a lower suction device. The perspective view seen from the back side of the downward suction device. The schematic perspective view explaining the structure of a suction shutter. FIG. 2 is a block diagram showing an example of a main configuration of a control system in the sheet feeding apparatus of the present embodiment. 5 is a flowchart showing an example of a feeding operation in the sheet feeding apparatus of the present embodiment.

Hereinafter, an embodiment of a sheet feeding apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram of an image forming system 1 of the present embodiment.
As shown in FIG. 1, the image forming system 1 includes an image forming apparatus 100 as an image forming unit that forms an image on a sheet, and a sheet feeding apparatus 200 that feeds a sheet to the image forming apparatus 100. . The sheet feeding apparatus 200 is provided on the side surface of the image forming apparatus 100 main body.

First, among the image forming apparatuses of the electrophotographic type and the ink jet type to which the sheet feeding apparatus of the present embodiment can be applied, the entire configuration and operation of the image forming apparatus will be described using the electrophotographic type image forming apparatus as an example. Do.
FIG. 2 is a schematic block diagram of the image forming apparatus 100 according to the present embodiment.
The image forming apparatus 100 is a full-color printer using four color toners of yellow (Y), magenta (M), cyan (C), and black (K), and a full-color copying machine having an equivalent image forming function. As shown in FIG. 2, four image forming units 101Y, 101M, 101C, and 101K for forming an image with toners of respective colors are arranged side by side in the upper part in the apparatus main body. The configuration and operation of each of the image forming units 101Y, 101M, 101C, and 101K are substantially the same, and therefore, the symbols (Y, M, C, and K) indicating colors are omitted here to describe the image forming unit. . In the image forming unit 101, a charger 103, a developing device 104, a cleaning device 105, and the like are disposed around a photosensitive drum 102 as an image carrier. An exposure unit 107 is disposed above the photosensitive drum 102.

  Below the four image forming units 101Y, 101M, 101C, and 101K, an intermediate transfer belt 108 wound around a plurality of support rollers is disposed. The intermediate transfer belt 108 is driven to travel in the direction of arrow A by driving one of the support rollers to rotate. A transfer roller 106 as a primary transfer unit is disposed to face the photosensitive drum 102 of each image forming unit with the intermediate transfer belt 108 interposed therebetween.

In each image forming unit 101, the photosensitive drum 102 is rotationally driven counterclockwise in the drawing, and the surface of the photosensitive member is uniformly charged to a predetermined polarity by the charger 103. Next, the charged surface is irradiated with the light modulated laser beam emitted from the exposure means 107, whereby an electrostatic latent image is formed on the photosensitive drum. The electrostatic latent image is developed by the toner applied from the developing device 104 and visualized as a toner image. The yellow, magenta, cyan, and black toner images formed by the image forming units are sequentially superimposed and transferred onto the intermediate transfer belt 108.

  On the other hand, the lower portion of the apparatus main body is provided with a feeding portion 114 having storage trays 114a and 114b. From either the feeding portion 114 or a sheet feeding device 200 described later attached to the image forming apparatus 100. For example, a sheet such as a transfer sheet is fed. The fed sheet is conveyed as indicated by arrow B toward the registration roller 111.

  The sheet that has been abutted against the registration roller 111 and temporarily stopped is delivered from the registration roller 111 in timing with the toner image on the intermediate transfer belt 108, and the secondary transfer roller 109 and the intermediate transfer belt 108 are in contact with each other. It is sent to the next transfer unit. A voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 109, whereby the superimposed toner image (full color image) on the intermediate transfer belt 108 is transferred onto the sheet. The sheet after the toner image transfer is conveyed to the fixing device 113 by the conveying belt 112, and the toner is fixed to the sheet by the heat and pressure in the fixing device 113. The sheet after fixing the toner image is discharged to the outside of the machine as indicated by arrow C, and is discharged onto the discharge tray.

  When the back side discharge (face-down discharge) is performed by single-sided printing, the sheet is discharged outside the machine as indicated by an arrow C through the sheet reversing unit 115, whereby the front and back of the sheet is reversed. Further, in the case of double-sided printing, the sheet after fixing is re-fed from the re-feed path 117 to the registration roller 111 through the double-sided reversing portion 116, and the toner image is transferred from the intermediate transfer belt 108 to the back of the sheet. The sheet after the toner image transfer is fixed by the fixing device 113, and as shown by the arrow C from the fixing device 113 as in single-sided printing, or outside the machine as shown by the arrow C through the sheet reversing portion 115. It is discharged and discharged onto the discharge tray. Switching claws 118 and 119 for switching the sheet conveyance direction are appropriately arranged.

  In the case of monochrome printing, in the image forming apparatus 100 of this embodiment, a toner image is formed using only the black (K) imaging unit 101K, and the toner image is transferred onto a sheet via the intermediate transfer belt 108. Do. The handling of the sheet after fixing the toner image is the same as in full color printing.

  A toner bottle setting unit 120 is provided on the upper surface of the apparatus main body for setting each color toner bottle 121 containing toner supplied to the developing device 104 of each image forming unit. Further, an operation unit 124 having a display unit 122 and an operation panel 123 is also provided on the upper surface of the apparatus main body. Furthermore, on the side surface on the right side of the apparatus main body, a sheet loading unit D from a sheet feeding device (see FIG. 3) described later is provided. In the sheet carry-in unit D, an opening 125 for receiving the sheet and a conveying means 126 for conveying the sheet are provided.

FIG. 3 is a schematic explanatory view of the sheet feeding apparatus 200 of the present embodiment provided on the side surface of the apparatus main body.
As shown in FIG. 3, the sheet feeding apparatus 200 includes the upper and lower two storage trays 10. Each accommodation tray 10 includes a sheet stacking table 11 on which the sheet bundle P is stacked. In the present embodiment, each storage tray 10 is capable of storing up to about 2500 sheets. The sheet includes paper, coated paper, label paper, OHP sheet, film, prepreg and the like. Prepregs are mainly used as materials for laminates and multilayer printed wiring boards. For example, a long base material such as glass cloth, paper, non-woven fabric, aramid cloth, etc. is continuously impregnated with a resin varnish mainly composed of a thermosetting resin such as epoxy resin or polyimide resin, and dried after heating and drying. Processed into sheet material. Above each storage tray 10, a feeding unit 20 for separating and feeding the sheets stacked on the storage tray 10 is disposed. The feeding unit 20 is provided with a suction belt 21 and an upper suction device 23 which are conveying means.

  The sheets stacked on the lower accommodation tray 10 are conveyed to the main body of the image forming apparatus 100 by the exit roller pair 80 through the lower conveyance path 82. The sheets stacked on the upper accommodation tray 10 are conveyed to the main body of the image forming apparatus 100 by the exit roller pair 80 through the upper conveyance path 81.

FIG. 4 is a schematic side view of the sheet feeding device 200 of the present embodiment. FIG. 5 is a schematic front view of the sheet feeding device 200. FIG. 6 is a schematic perspective view of the sheet feeding device 200. FIG. 7 is a schematic perspective view of the blower and the lower suction device.
As shown in FIG. 4, the suction belt 21 of the feeding unit 20 as sheet conveying means is stretched by two stretching rollers 22a and 22b, and penetrates from the front surface side to the back surface side of the belt. Suction holes are provided in the entire circumferential direction. An upper suction device 23 is provided inside the suction belt 21. The upper suction device 23 is connected to an upper suction fan that sucks air through an air duct, which is a flow path of air, and generates a negative pressure downward by the upper suction device 23 so that the sheet is attached to the lower surface of the suction belt 21. Acts to adsorb.

  Further, the storage tray 10 is provided with a blower 24 as air blowing means for blowing air to the upper portion of the sheet bundle P and a lower suction device 25 as air suction means for suctioning air in the vicinity of the upper portion of the sheet bundle P. Prepare.

  The blower 24 has a front blower 26 and a side blower 27. As shown in FIGS. 4 and 5, the front air blower 26 blows air to the top end (the downstream end in the feeding direction) of the sheet bundle P. In the front air blower 26, air is blown to the floating nozzle 26a that blows air in a direction to make the sheet in the upper part of the sheet bundle P float, and the suction belt 21 and is reflected on the suction belt 21 to be the first sheet. A separation nozzle 26b is provided which discharges air for directing the upper sheet and the other sheets downward. Furthermore, a separation air chamber 31b communicating with the floating nozzle 26a and a separation air chamber 31b communicating with the separation nozzle 26b are disposed. Inside the floating air chamber 31a and the separation air chamber 31b, a floating / separation shutter 32 is provided which momentarily shuts off and opens the air in the floating air chamber 31a and the separation air chamber 31b.

  A blower fan for feeding air is disposed in each of the floating air chamber 31a and the separation air chamber 31b. Further, the air blown in the direction indicated by the arrow a1 in the drawing from the rising nozzle 26a is referred to as front floating air, and the air blown in the direction indicated by the arrow a2 in the drawing from the separation nozzle 26b is referred to as separation air. The floating air and the separation air are discharged from a position facing the top end (the feeding direction downstream end) of the sheet bundle P, and are blown to the top end (the feeding direction downstream end) of the sheet bundle P .

  Further, as shown in FIG. 6, the side blowers 27 are provided on a pair of side fences 28 for positioning so that the sheet is not skewed in the width direction corresponding to the direction perpendicular to the feeding direction. ing. The sheet feeding device 200 is a center reference for moving both of the two side fences 28 in the width direction according to the sheet size. Then, the side fence 28 is provided with a side air blower 27 for pushing air to the vicinity of the widthwise side end of the upper portion of the sheet bundle P to lift and loosen the sheet.

  In the side air blower 27, a side levitation nozzle front 27a arranged to face the sheet bundle P and guide air in a direction to float and to face the front side in the sheet feeding direction in the sheet side, and the sheet side And a rear side floating nozzle 27b disposed opposite to the rear side in the feeding direction. The air blown from these nozzles is called side levitation air. The side floating air is discharged from a discharge port provided at a position facing the upper portion of the sheet bundle P of each side fence 28 and is blown to the side surface of the upper portion of the sheet bundle P. The air blown from the nozzles of the front air blower 26 and the side air blower 27 causes the sheet at the top of the sheet bundle P to float. Further, as shown in FIG. 6, the storage tray 10 is provided with an end fence 29 for aligning the rear end of the sheet bundle P stacked on the sheet stacking table 11.

  The lower suction device 25 sucks the air in the vicinity of the front end of the upper portion of the sheet bundle P downward to generate a negative pressure, as shown in FIG. 4, FIG. 5 and FIG. Function. In the lower suction device 25, a lower suction nozzle 25a for suctioning air in the vicinity of the front end at the upper portion of the sheet bundle P downward, and a lower suction air chamber 33 communicating with the lower suction nozzle 25a are disposed. The lower suction air chamber 3 is provided with a lower suction fan 42 which is suction means for suctioning air. Further, inside the lower suction air chamber 33, a lower suction shutter 34 is provided as an open / close mechanism that instantaneously switches blocking / opening of ventilation in the lower suction air chamber 33.

  As shown in FIG. 7, the sheet feeding device 200 is a sheet upper surface sensor which is a sheet height detecting means for detecting the height of the upper surface of the uppermost sheet on the upstream side of the suction belt with respect to the suction belt. It has 41.

  In the sheet feeding apparatus 200, the distance between the upper surface of the topmost sheet in the storage tray and the lower surface of the suction belt in which the number of sheets is reduced by the feeding needs to be within a certain range. For this reason, the height of the upper surface of the uppermost sheet is detected by the sheet upper surface sensor 41, and based on the detection signal of the sheet upper surface sensor 41, the bottom plate is moved up and down. Control the drive of the motor. Thus, the height of the bottom plate can be adjusted, and the distance between the top surface of the uppermost sheet of the sheet bundle placed on the bottom plate and the bottom surface of the suction belt can be controlled within a certain range.

  Further, the accuracy of the stop position in the height direction of the sheet loading platform detected by the sheet upper surface sensor 41 can be improved for the following reason (see FIG. 7). That is, the detection of the stop position when raising and lowering the sheet loading table is performed on the sheet upper surface sensor 41 and the upper surface of the sheet, and if the air enters between the sheets and the sheet is floating, accurate upper surface detection can not be performed. Therefore, by closing the front floating air and the separation air with a shutter and dropping the sheet, accurate detection of the top surface height of the uppermost sheet becomes possible. In addition to the upstream side of the suction belt in the feeding direction, the sheet upper surface sensor 41 may be provided on the side surface orthogonal to the feeding direction, or a plurality of sheet top sensors 41 may be provided.

FIG. 8 is a perspective view of the lower suction device 25 as viewed from the front side. FIG. 9 is a perspective view of the lower suction device 25 as viewed from the back side. FIG. 10 is a schematic perspective view illustrating the configuration of the lower suction shutter 34. As shown in FIG.
As shown in FIGS. 8, 9 and 10, the lower suction nozzle 25a lowers the air in the vicinity so as to make the vicinity of the leading edge at the top of the sheet bundle a negative pressure by the negative pressure generated by the lower suction fan 42. Suction. Two lower suction nozzles 25a are disposed between the floating nozzle 26a and the separation nozzle 26b. Further, the lower suction nozzle 25a is arranged to restrict the feeding of the sheet to be fed to the leading end of the sheet fed after the uppermost sheet in the height direction, and the leading end of the second sheet (other sheet) It also has a function as a blocking plate that suppresses double feeding with the first sheet (uppermost sheet). Even when the second sheet is to be fed together with the first sheet, the leading end of the lower suction nozzle 25a can hit the leading end of the second sheet, thereby suppressing double feeding.

  Furthermore, the tip of the lower suction nozzle 25a is arranged to suction at a position close to the uppermost sheet in the height direction. As a result, if the one closer to the top sheet is suctioned, the separation effect is enhanced, so it is more effective to make the gap with the suction belt relatively smaller, but a gap through which the top sheet passes is also required. The gap is preferably about 1 to 3 mm. The clearance is adjusted by the height of the lower suction nozzle 25a with a mounting screw as an adjustment means. In addition, the tip of the lower suction nozzle 25a may be deteriorated because the side surface and the top surface come in contact with the sheet and wear occurs. Therefore, by applying a surface treatment such as metal plating on the side surface and the upper surface at the tip of the lower suction nozzle 25a, the deterioration can be suppressed and the product life can be extended.

  In suction by the lower suction nozzle 25a, the lower suction shutter 34 switches between open and shut by reciprocating the tension shaft of the solenoid 36 in the direction indicated by the arrow b1 in FIG. The lower suction shutter 34 is connected to the solenoid 36 via the pulling shaft 35, and shuts off / opens suction air in the lower suction air chamber 33 by turning on / off the solenoid 36 controlled by the control unit 60 described later. Is switched. Specifically, the lower suction shutter 34 is in a state where the solenoid is not energized and no solenoid suction force is applied, that is, in the OFF state, the lower suction shutter 34 is pulled by the spring 37. As a result, the lower suction shutter 34 is disposed horizontally with respect to the air suction direction.

  On the other hand, when the solenoid 36 is in an energized state and the solenoid suction force acts and suction is complete, that is, in the ON state, the lower suction shutter 34 slides to the solenoid side and the lower suction air by the lower suction fan 42 is lower air Open the vents in the chamber. By driving the lower suction fan 42 in this state, the lower suction air flows from the lower suction nozzle 25a in the direction indicated by arrow a3 in FIG. 9, and is discharged in the direction indicated by arrow a4 in FIG.

Next, feed control according to the present embodiment will be described.
FIG. 11 is a block diagram showing an example of a main configuration of a control system in the sheet feeding apparatus 200 of the present embodiment.
As shown in FIG. 11, the control unit 60 as the control means of the sheet feeding apparatus 200 includes a belt suction fan 61 for generating a negative pressure for suctioning the sheet to the suction belt, a front blower and a side blower. A blower fan 62 for blowing air toward each, a solenoid 63 for operating the side float air shutter, a solenoid 64 for operating the front float air shutter, a solenoid 65 for operating the separation air shutter, and an upper suction shutter A solenoid 66, a solenoid 36 for operating the lower suction shutter, a lower suction fan 42 of a lower suction device for suctioning air near the upper portion of the sheet bundle P, and a suction belt 21 are connected.

Next, an operation in the case of feeding sheets one by one by the sheet feeding apparatus will be described.
FIG. 12 is a flowchart showing an example of the feeding operation in the sheet feeding apparatus 200 of the present embodiment.
The upper controller of the image forming apparatus receives an image forming instruction using a sheet set on the storage tray 10 of the sheet feeding apparatus 200 from the operation unit of the image forming apparatus (see FIG. 4). Then, a control instruction of the sheet feeding apparatus 200 and information such as the type of sheets stacked on the sheet stacking table of the storage tray are transmitted from the upper controller (see FIG. 11). When receiving the feeding instruction, the control unit 60 confirms that the shutters of the side floating air, the front floating air, the separation air, the upper suction air and the lower suction air are in the initial state, with the suction belt stopped. If there is a shutter that is not in the initial state, the initial state is set (S1). The initial state of each shutter of side float air, front float air, separation air, and upper suction air is "open (open state)", while the initial state of lower suction air is "closed (closed state)" . As described later, since the feeding operation is ended after each shutter is in the initial state, normally, each shutter is in the initial state at the start of the feeding operation.

  Next, the control unit 60 operates the side levitation air, the front levitation air and the separate air blower fans, the belt suction fan of the upper suction air, and the lower suction fan of the lower suction air. Then, a pre-saver operation for 5 seconds is performed (S2). In the present embodiment, although the preliminary separation operation is 5 seconds, the present invention is not limited to this, and may be appropriately set according to the configuration of the apparatus.

  At the time of this preliminary clearance operation, the shutters of the side float air and the front float air are opened. Therefore, side floating air or front floating air is blown to both sides and the tip side of the upper part of the sheet bundle P, and among the upper parts of the sheet bundle P, the first sheet of the uppermost sheet and several sheets after the second sheet To rise. Further, in the preliminary separation operation, since the shutter of the separation air is also opened, the first sheet and the second and subsequent sheets are separated by the separation air. Furthermore, in the preliminary separation operation, since the shutter of the upper suction air is also released, the first sheet which has floated up is adsorbed to the suction belt.

  When the preliminary separation operation is completed (five seconds after the start of the operation of each fan), the suction belt is rotated to feed the first sheet. At this time, if the second sheet as the second sheet excessively floats or disturbs the behavior and contacts the first sheet, the sheet bundle may be conveyed together with the first sheet. Therefore, in the present embodiment, when the preliminary clearance operation is completed, the shutters of the front floating air and the separation air are closed, and the second floating sheet is dropped so as not to contact the first sheet. Suppress double feed (S3). Further, the shutter of the lower suction air is opened to start the lower suction (S4). The shutter of the lower suction air is closed until the preliminary operation is completed. Thus, in the preliminary separation operation, the first sheet can be favorably adsorbed to the adsorption belt without being hindered by the lower suction air. As described above, double feeding of the second sheet is suppressed, and in the preliminary separation operation, the first sheet is favorably absorbed without being impeded by the lower suction air due to the floating of the first sheet and the adsorption onto the suction belt. It can be attracted to the belt. Then, driving of the feeding motor is started, and feeding is started by rotating the suction belt to which the first sheet is sucked (S5).

  When a predetermined time has elapsed from the start of feeding (when the leading end of the first sheet is fed to a predetermined next step (for example, a conveying roller pair) downstream of the suction belt), the shutter of the upper suction air is closed and suction is performed. Release the first sheet attached to the belt (SS6). Also, the drive of the feed motor is stopped to stop the suction belt (S7).

  Next, the control unit determines whether there is a sheet to be fed (S8). When there is a sheet to be fed (YES in S8), the shutter of the front floating air is opened, and the blowing of the front floating air to the top end side of the sheet bundle P is resumed, and the shutter of the separation air is opened. And restart blowing of separated air (S9).

  Next, the control unit closes the shutter of the lower suction air to prevent the lower suction air from obstructing the floating of the second sheet fed next. Next, the shutter of the upper suction fan is opened to resume sheet suction to the suction belt (S11). As a result, the second sheet can be adsorbed to the suction belt well. Then, the processing of S3 to S8 is performed to feed the sheet.

  In S8, S3 to S11 are repeated until the number of sheets to be fed reaches the set number, and when the number of sheets to be fed reaches the set number and there is no next feeding (NO in S8), each shutter is in the initial state ( After S12), the operation of each fan is stopped to complete the feeding operation.

  In the above feeding operation, the shutter of the lower suction air closed in S4 is opened in accordance with the closing of the shutter of the front floating air and the shutter of the separation air in S3. As a result, air is sucked from the front of the first sheet by the lower suction air to generate a negative pressure. As a result, it is possible to suppress the double feeding by accelerating the falling speed of the second sheet. Also, as the feeding operation of the second sheet, the front floating air and the separation air are blown again, the second sheet is floated, and adsorption is performed by the suction belt, but in order to improve productivity, Immediately after the shutter of the upper suction air is opened (without waiting for 5 seconds). At this time, if the shutter for the lower suction air is open, it takes time for the second resurfacing operation to take time, and there is a possibility that the sheet may be fed without being well adsorbed by the suction belt, which may result in a defect feed. There is. Therefore, by closing the lower suction shutter in S10 and stopping the lower suction air, it is possible to accelerate the re-flying speed of the second sheet and quickly adsorb the second sheet to the suction belt favorably. As a result, even if the operation after S3 is performed immediately (without waiting for 5 seconds) after the shutter of the upper suction air is opened, the second and subsequent sheets can be adsorbed to the suction belt favorably, and the second sheet It is possible to suppress feeding failure after the sheet.

  In addition, immediately after the shutter of the front floating air and the shutter of the separation air are released by the resurfacing operation of the second sheet, the second sheet jumps up and comes into contact with the first sheet being conveyed, and the double feed double feed It causes the outbreak. So, in this embodiment, as shown to S9 and S10, the shutter of lower suction air is closed, for example, 50 [ms]-150 [ms] progress, after releasing the shutter of front levitation air. As a result, the second sheet to be bounced can be sucked downward by the lower suction air, and it can be suppressed that the second sheet comes into contact with the first sheet being conveyed. Therefore, it is possible to suppress the simultaneous feed and double feed.

  As described above, when the sheet is adsorbed to the suction belt, the sheet can be favorably floated by closing the shutter of the lower suction air to stop the action of the suction force on the sheet. Therefore, the occurrence of sheet feeding failure can be suppressed.

  In the present embodiment, as the switching means, a mechanism for sliding the shutter by switching the solenoid to the non-energized state or the energized state and switching the blocking or opening of the air has been described as an example, but the present invention is not limited thereto. For example, a so-called butterfly valve is provided with a disc-like valve body having a diameter equal to the inner diameter of the air passage in a cylindrical air passage, which is pivoted about a diameter axis to block or open the air passage. It may be a mechanism of switching the Alternatively, an air passage is formed of a flexible resin or the like, and the air passage is pressed from the outside to crush the air passage, thereby blocking the air passage in the air passage or releasing the pressure. It may be configured to open the air. As the feeding means, the sheet is attracted to the feeding belt by negative pressure. However, the present invention is not limited to this. The sheet may be electrostatically attracted to the feeding belt using static electricity.

The above-described one is an example, and each mode has the unique effect.
(Aspect A)
The air is blown to the sheet bundle P stacked on the sheet stacking table 11 by the air blowing means such as the blower 24 so that the uppermost sheet is separated from the sheet bundle and fed by the feeding means such as the feeding unit 20. The sheet feeding apparatus 200 includes an air suction unit such as a lower suction unit 25 that sucks air so that a force acting in a direction away from the feeding unit acts on the sheet in the vicinity of the topmost sheet. The suction means includes a suction nozzle such as the lower suction nozzle 25a for suctioning air, a suction fan such as the lower suction fan 42 for generating a negative pressure, and a lower suction air chamber for ventilating between the suction nozzle and the suction fan. And a suction duct such as 33, and is provided with an open / close mechanism such as a lower suction shutter 34 for blocking and opening ventilation in the suction duct. .
In Patent Document 1 described above, air suction can not be shut off when air suction is unnecessary. As a result, for example, the following problem may occur. That is, the air suction of the suction nozzle also inhibits the action of the blowing air when the uppermost sheet is lifted from the sheet bundle by the blowing of the air. As a result, it takes a long time for the topmost sheet to be adsorbed to the suction belt, which causes a delay in sheet feeding, or causes the topmost sheet not to be adsorbed to the suction belt but causes non-feeding of the sheet. Is likely to occur.
In this aspect, it is possible to shut off the ventilation in the suction duct by the opening and closing mechanism. Thereby, air suction can be shut off when air suction is unnecessary. Therefore, an air suction stop period in which the air suction operation by the air suction means is stopped is provided, for example, within the air blowing period in which the air is blown by the air blowing means. In this air suction stop period, the action of the blowing air for separating the top sheet from the sheet bundle is not hindered. Therefore, the uppermost sheet can be separated from the sheet bundle without being obstructed by the air suction operation, and sheet feeding delay and sheet non-feeding due to the air suction operation can be suppressed.

(Aspect B)
(Aspect A), including control means such as a control unit 60 that performs control to switch between blocking and opening in the suction duct by the opening and closing mechanism, the control means blowing air from the air blowing means, The opening and closing mechanism is controlled to provide a period for blocking air flow in the suction duct, and when air blowing by the air blowing means is stopped, the period for opening the air flow in the suction duct is provided. It is characterized by controlling a mechanism.
According to this aspect, in the period when the air suction is stopped, the action of the blowing air for separating the top sheet from the sheet bundle is not hindered. During the air suction period, other sheets can be separated from the uppermost sheet adsorbed to the suction belt to suppress double feeding. Therefore, the uppermost sheet can be separated from the sheet bundle without being obstructed by the air suction operation, and sheet feeding delay and sheet non-feeding due to the air suction operation can be suppressed.

(Aspect C)
In (Aspect B), the control means controls the open / close mechanism to open the ventilation in the suction duct after a predetermined time has elapsed since the air blowing by the air blowing means is stopped. .
According to this aspect, by delaying the stopping of the action of the force moving away from the feeding means for a predetermined time, suction of the excessively floated sheet toward the sheet stacking table by the action of the force moving away from the feeding means As a result, it is possible to reliably suppress the sheet from floating excessively and to suppress the occurrence of feeding failure.

(Aspect D)
In (Aspect A) to (Aspect C), the suction nozzle is disposed such that the tip of the suction nozzle hits the tip of the sheet to be fed from the uppermost sheet onward in the height direction, and regulates feeding of the sheet. It is characterized by being.
According to this aspect, it is possible to reduce the problem that the sheet is caught by the tip of the suction nozzle and the feeding failure occurs.

(Aspect E)
(Aspect A) to (Aspect D), the tip of the suction nozzle is arranged such that the suction nozzle suctions a position near the uppermost sheet in the height direction.
According to this aspect, by suctioning a portion close to the top sheet with the suction nozzle, the effect of separation from other sheets is enhanced. Further, by quickly sucking another sheet approaching the topmost sheet and quickly releasing it from the sheet, double feeding can be suppressed in a short time, and feeding of each sheet can be performed at high speed.

(Aspect F)
In any one of Aspects A to E, the apparatus further comprises an adjustment unit that adjusts the position of the suction nozzle in the height direction.
According to this aspect, the suction position can be adjusted, and the suction position is adjusted to reduce the variation of the apparatus.

(Aspect G)
In any of (Aspect A) to (Aspect F), a surface treatment to reduce wear is performed on at least a portion of the suction nozzle where the sheet hits.
According to this aspect, it is possible to suppress the deterioration of the suction nozzle and extend the life of the device.

(Aspect H)
In any of (Aspect A) to (Aspect G), a sheet surface sensor such as a sheet upper surface sensor 41 for detecting the uppermost position of the sheet bundle is disposed in the vicinity of the suction nozzle.
According to this aspect, if the sheet surface sensor and the upper surface of the sheet detect the stop position when moving the sheet loading table up and down, if the air enters between the sheets and the sheet floats, the upper surface is accurately detected Can not do. Therefore, the top surface height of the uppermost sheet of the sheet bundle can be accurately detected by dropping the uppermost sheet of the sheet bundle to the sheet bundle side by the action of the suction force by the suction nozzle.

(Aspect I)
In the image forming apparatus 100 provided with an image forming unit that forms an image on a sheet and a feeding unit that feeds the sheet toward the image forming unit, (mode A) to (mode H) as the feeding unit The sheet feeding apparatus according to any one of the above is used.
According to this aspect, it is possible to provide an image forming apparatus capable of suppressing the occurrence of feeding failure.

(Aspect J)
In the image forming system 1 including at least an image forming apparatus 100 including an image forming unit for forming an image on a sheet, and a sheet feeding apparatus 200 for feeding a sheet toward the image forming apparatus, the sheet feeding apparatus The sheet feeding device according to any one of (Aspect A) to (Aspect H) is used.
According to this aspect, it is possible to provide an image forming system capable of suppressing the occurrence of feeding failure.

1: Image forming system 10: Storage tray 11: Sheet loading table 20: Feeding unit 21: Adsorption belt 22a: Stretching roller 22b: Stretching roller 23: Upper suction device 24: Blower 25: Lower suction device 25a: Lower Suction nozzle 26: front blower 26a: levitation nozzle 26b: separation nozzle 27: side blower 27a: side levitation nozzle front 27b: side levitation nozzle 28: side fence 29: end fence 31a: levitation air chamber 31b: separation air chamber 32: floating / separating shutter 33: lower suction air chamber 34: lower suction shutter 35: tension shaft 36: solenoid 37: spring 41: sheet upper surface sensor 42: lower suction fan 60: control unit 61: belt suction fan 62: blowing fan 63: Renoid 64: solenoid 65: solenoid 80: outlet roller pair 81: upper conveying path 82: lower conveying path 100: image forming apparatus 101: imaging unit 101C: imaging unit 101K: imaging unit 101M: imaging unit 101Y: imaging Image unit 102: Photosensitive drum 103: Charging device 104: Development device 105: Cleaning device 106: Transfer roller 107: Exposure device 108: Intermediate transfer belt 109: Secondary transfer roller 111: Registration roller 112: Conveying belt 113: Fixing device 114: feeding portion 114a: storage tray 115: sheet reversing portion 116: double-sided reversing portion 117: refeeding path 118: switching claw 119: switching claw 120: toner bottle setting portion 121: color toner bottle 122: display portion 123: Operation panel 124: Operation unit 125: Opening 126: Conveying means 200: Sheet feeding device P: Sheet bundle

JP, 2011-162321, A

Claims (10)

In the sheet feeding apparatus, the air is blown to the sheet bundle stacked on the sheet loading table by the air blowing unit to raise the uppermost sheet from the sheet bundle and to feed the sheet by the feeding unit,
An air suction unit for suctioning air so that a force acting in a direction away from the feeding unit acts on the sheet in the vicinity of the topmost sheet;
The air suction means has a suction nozzle for suctioning air, a suction fan for generating a negative pressure, and a suction duct for ventilating between the suction nozzle and the suction fan, and the air duct in the suction duct What is claimed is: 1. A sheet feeding apparatus comprising: an opening and closing mechanism for blocking and opening. In the sheet feeding device according to claim 1,
Control means for controlling switching between blocking and opening in the suction duct by the opening and closing mechanism;
The control means controls the opening / closing mechanism so as to provide a period for blocking ventilation in the suction duct when blowing air by the air blowing means, and stops blowing of air by the air blowing means. The sheet feeding device according to claim 1, wherein the opening and closing mechanism is controlled so as to provide a period for opening the ventilation in the suction duct. In the sheet feeding device according to claim 2,
The sheet feeding device, wherein the control means controls the opening and closing mechanism to open the ventilation in the suction duct after a predetermined time has elapsed since the air blowing by the air blowing means is stopped. The sheet feeding apparatus according to any one of claims 1 to 3.
The suction nozzle is arranged so that the leading end of the suction nozzle contacts the leading end of the sheet to be fed after the uppermost sheet in the height direction, and restricts the feeding of the sheet. Feeder. The sheet feeding apparatus according to any one of claims 1 to 4.
The tip of the suction nozzle is disposed such that the suction nozzle suctions a position close to the uppermost sheet in the height direction. The sheet feeding device according to any one of claims 1 to 5.
A sheet feeding apparatus comprising: adjustment means for adjusting the position of the suction nozzle in the height direction. The sheet feeding device according to any one of claims 1 to 6.
A sheet feeding apparatus characterized in that surface treatment for reducing wear is applied to at least a portion where the sheet hits the suction nozzle. The sheet feeding apparatus according to any one of claims 1 to 7.
A sheet feeding apparatus, wherein a sheet surface sensor for detecting the uppermost position of the sheet bundle is disposed in the vicinity of the suction nozzle. An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and a feeding unit that feeds the sheet to the image forming unit,
An image forming apparatus comprising the sheet feeding device according to any one of claims 1 to 8 as the feeding means. 1. An image forming system comprising: an image forming apparatus comprising image forming means for forming an image on a sheet; and a sheet feeding apparatus for feeding a sheet toward the image forming apparatus,
An image forming system using the sheet feeding device according to any one of claims 1 to 8 as the sheet feeding device.

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