Sheet Feeding Device

Abstract

To provide a sheet feed device capable of reducing labor of releasing jamming and having less wasteful paper while suppressing generation of dust.SOLUTION: An induction guide 10 guides paper P, conveyed from a fed paper conveyance part 12 toward a paper feed stand 2 in a reverse conveying direction D2, to a conveying surface 26a of a suction conveyance part 8. A control part 13, when jamming of the paper P occurs at the fed paper conveyance part 12, controls the suction conveyance part 8 and the fed paper conveyance part 12 so as to convey reusable paper P in the reverse conveying direction D2 to return it from the fed paper conveyance part 12 to the paper feed stand 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device that feeds sheets. [Background technology]

[0002] A known sheet supplying device for supplying sheets is one that blows air onto a stack of sheets of paper stacked on a paper supply tray to lift the sheets, removes the topmost (uppermost) sheet of the lifted sheets from the paper supply tray by adsorbing and transporting it with an adsorption and transporting means, and transports the sheet with a transport roller to feed it to a printing device.

[0003] Further, as a paper feeder of this type, there is known one which is provided with a blocking member that blocks the floating sheets other than the uppermost sheet adsorbed by the suction transport means in order to prevent double feeding of sheets.

[0004] In the above-mentioned paper feeder, a paper jam may occur while being fed by the feed roller. If a jam occurs during continuous paper feeding, the paper feed stops and the paper remains in the feed path. In this case, paper other than the one causing the jam is also targeted for clearing, and usable paper may go to waste.

[0005] In response to this, Patent Document 1 discloses a paper feeder that, when a jam occurs, drives a conveying roller in the reverse direction to return the paper to the paper feed tray for reuse. This paper feeder can reduce the effort required to clear a jam and the amount of paper wasted (damaged paper).

[0006] In the paper feeder of Patent Document 1, the blocking member is configured to be vertically changeable (liftable). When returning the paper to the paper feed tray, the blocking member is lowered so that it does not interfere with the return of the paper. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2014-223978 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the paper feeding device of the above-mentioned Patent Document 1, when the blocking member is raised and lowered, the blocking member rubs against the stack of papers in the paper feed tray, generating paper powder (dust).

[0009] The present invention has been made in view of the above, and has an object to provide a sheet feeding device that can reduce the effort required to clear jams and the amount of wasted sheets while suppressing the generation of dust. [Means for solving the problem]

[0010] In order to achieve the above object, a sheet supplying device of the present invention includes a stacking table on which a stack of sheets is stacked, a floating portion that blows air onto the stack of sheets to float a plurality of sheets from the stack of sheets, a first conveying portion that holds a topmost sheet of the plurality of sheets floated by the floating portion on a conveying surface and conveys the topmost sheet, a non-movable blocking member that blocks sheets other than the topmost sheet conveyed by the first conveying portion, and a blocking member that is disposed downstream of the blocking member in a conveying direction of the topmost sheet by the first conveying portion and that is conveyed by the first conveying portion. The device is characterized by comprising a second conveying section which conveys the conveyed sheet downstream in the conveying direction, a guide which is arranged between the blocking member and the second conveying section and which guides the sheet conveyed from the second conveying section towards the loading platform in the opposite direction to the conveying direction to the conveying surface of the first conveying section, and a control section which controls the first conveying section and the second conveying section to convey a reusable sheet in the opposite direction to the conveying direction and return it from the second conveying section to the loading platform when a sheet jam occurs in the second conveying section. Effect of the Invention

[0011] According to the sheet feeding device of the present invention, it is possible to reduce the effort required for clearing jams and the amount of wasted sheets while suppressing the generation of dust. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a paper feed device according to an embodiment; [Diagram 2] 2 is a control block diagram of the paper feeder shown in FIG. 1. [Diagram 3] FIG. 13 is a diagram showing a state in which a plurality of sheets of paper are floated. [Figure 4] 13 is a diagram showing how the second and subsequent sheets of paper from the top of the floated sheets fall. FIG. [Diagram 5] 13 is a flowchart of a paper collection process. [Figure 6] 13A and 13B are diagrams illustrating a state in which a sheet is guided by a guide to a conveying surface of a suction conveying unit during a sheet collection process. [Figure 7] 13A and 13B are diagrams illustrating a state in which the paper reaches an end fence during the paper collection process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts and components are denoted by the same or equivalent reference numerals throughout the drawings.

[0014] The following embodiments are examples of devices for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the material, shape, structure, arrangement, etc. of each component to those described below. The technical idea of ​​the present invention can be modified in various ways within the scope of the claims.

[0015] Fig. 1 is a schematic configuration diagram of a paper feeder according to an embodiment of the present invention. Fig. 2 is a control block diagram of the paper feeder shown in Fig. 1. In the following description, the top, bottom, left and right directions on the paper surface of Fig. 1 are defined as the top, bottom, left and right directions.

[0016] As shown in Figures 1 and 2, the paper feeding device (corresponding to a sheet supplying device) 1 of this embodiment includes a paper feeding table (corresponding to a loading table) 2, an end fence 3, a lifting motor 4, an encoder 5, a floating section 6, a separation section 7, an adsorption conveying section (corresponding to a first conveying section) 8, a blocking member 9, an induction guide 10, an upper limit sensor 11, a paper feeding conveying section (corresponding to a second conveying section) 12, and a control section 13.

[0017] The paper feeder 1 is a device that feeds paper (corresponding to a sheet) P to a printing device (not shown). The path indicated by the dashed line in Fig. 1 is the paper feed path R along which the paper P fed to the printing device is transported. During the paper feed operation, the paper P is transported in a transport direction D1 from the paper feed tray 2 toward the printing device. In the following description, upstream and downstream refer to upstream and downstream in the transport direction D1, unless otherwise specified.

[0018] The paper feed tray 2 is configured to be capable of being raised and lowered, and is configured to hold paper P to be used for printing.

[0019] The end fence 3 is a member that regulates the position of the upstream end (left end) of the paper P on the paper feed tray 2.

[0020] The lifting motor 4 lifts and lowers the paper feed tray 2 .

[0021] The encoder 5 outputs a pulse signal for each predetermined rotation angle of the rotation shaft of the lift motor 4.

[0022] The floating unit 6 blows air from the downstream side onto a paper stack (corresponding to a sheet stack) PT consisting of multiple papers P stacked on the paper feed tray 2, and floats the multiple papers P at the upper end of the paper stack PT. The floating unit 6 includes a floating fan 16 and a floating shutter 17.

[0023] The floating fan 16 generates a floating air current A1 (see FIG. 3) for floating the sheets P of the sheet stack PT on the sheet feed tray 2.

[0024] The floating shutter 17 switches on and off the blowing of the floating air current A1 onto the stack of paper-sheets PT.

[0025] Two floating portions 6 may be further provided, facing each other with the stack of paper sheets PT on the paper feed tray 2 sandwiched therebetween in the width direction of the paper sheets P perpendicular to the transport direction D1.

[0026] The separating section 7 separates the uppermost sheet P, which has been floated by the floating section 6 and adsorbed to the adsorption transport section 8, from the second and subsequent sheets P from the top. The separating section 7 includes a separation fan 18.

[0027] The separation fan 18 generates a separation airflow A2 (see FIG. 3) for blowing air between the topmost sheet P adsorbed to the adsorption and transport section 8 and the second sheet P from the top, thereby separating the topmost sheet P from the sheets P below the second sheet from the top.

[0028] Two separation sections 7 may be further provided, facing each other in the width direction of the paper P with the paper stack PT on the paper feed tray 2 sandwiched therebetween.

[0029] The suction transport section 8 uses air suction to suction and transport the uppermost sheet P of the multiple sheets P floated by the floating section 6. The suction transport section 8 includes a belt unit 21 and a suction mechanism section 22.

[0030] The belt unit 21 attracts and holds the paper P and transports the paper P. The belt unit 21 includes a transport belt 26, a drive roller 27, a driven roller 28, and a transport motor 29.

[0031] The conveyor belt 26 is a circular belt stretched over a drive roller 27 and a driven roller 28. A plurality of belt holes (not shown) are formed around the entire circumference of the conveyor belt 26. The conveyor belt 26 attracts and holds the paper P on the conveyor surface 26a by an attraction force generated in the belt holes by the drive of the suction mechanism unit 22. The conveyor surface 26a is the lower surface of the lower part of the conveyor belt 26 between the drive roller 27 and the driven roller 28. With the paper P attracted and held, the conveyor belt 26 rotates (moves endlessly) by the drive of the drive roller 27, thereby conveying the paper P.

[0032] The drive roller 27 rotates (endlessly moves) the conveyor belt 26. The drive roller 27 is configured to be capable of rotating forward and reverse. When the drive roller 27 is driven to rotate forward, the belt unit 21 is driven to rotate forward, so that the paper P can be conveyed in the conveying direction D1, and when the drive roller 27 is driven to rotate in the reverse direction, the belt unit 21 is driven to rotate in the reverse direction, so that the paper P can be conveyed in the reverse conveying direction D2 that is the opposite direction to the conveying direction D1.

[0033] The driven roller 28 supports the conveyor belt 26 together with the drive roller 27. The driven roller 28 rotates in response to the rotation of the conveyor belt 26.

[0034] The conveying motor 29 drives the drive roller 27 to rotate in the forward and reverse directions.

[0035] The suction mechanism 22 sucks air through the belt holes of the conveyor belt 26, thereby adsorbing the paper P to the conveyor belt 26. The suction mechanism 22 includes a fan (not shown) that generates a suction airflow A3 (see FIG. 3) to suck air through the belt holes. The suction mechanism 22 also includes a suction shutter 30 that switches the suction airflow A3 on and off.

[0036] The damming member 9 blocks the sheets P other than the uppermost sheet P transported by the suction transport section 8 among the multiple sheets P floated by the floating section 6. The damming member 9 is a non-movable (fixed) member disposed near the lower downstream end of the suction transport section 8. The damming member 9 is disposed so that the distance between its upper end and the transport surface 26a of the suction transport section 8 is a predetermined distance.

[0037] The guide 10 guides the paper P, which is transported in the reverse transport direction D2 from the paper feed conveying section 12 toward the paper feed tray 2 in a paper recovery process described later, to the transport surface 26a of the suction transport section 8. The guide 10 is a non-movable (fixed) member disposed between the blocking member 9 and the paper feed conveying section 12 so as to be in contact with the blocking member 9.

[0038] The leading guide 10 has a guide surface 10a formed so as to become lower toward the downstream side in the conveying direction D1 (upstream side in the reverse conveying direction D2). The upper end of the guide surface 10a is at the same height as the upper end of the blocking member 9. The guide surface 10a guides the paper P conveyed in the reverse conveying direction D2 from the paper feed conveying section 12 toward the paper feed table 2 to the conveying surface 26a of the suction conveying section 8.

[0039] By using such an induction guide 10, even if the blocking member 9 is configured to be non-movable (fixed) and not rise or fall, the blocking member 9 is prevented from interfering with the return of the paper P to the paper feed table 2, and the paper P can be smoothly collected on the paper feed table 2.

[0040] The upper limit sensor 11 monitors the downstream (right) end face of the paper P loaded on the paper feed tray 2. The upper limit sensor 11 is disposed downstream of the paper feed tray 2 at a height position where it can detect the paper P floating in the floating area F (see FIG. 3). The floating area F is an area in the vertical direction where the floating part 6 floats the paper P. The upper limit sensor 11 is made of a reflective photosensor, and includes a light-emitting unit 31 and a light-receiving unit 32.

[0041] The light emitting unit 31 emits light from the right side of the stack of paper-sheets PT on the paper feed tray 2 to the left side (the stack of paper-sheets PT side).

[0042] The light receiving section 32 receives light from the left side (the side of the stack of paper sheets PT).

[0043] The paper feed conveying section 12 conveys the paper P conveyed by the suction conveying section 8 along a paper feed path R toward a printing device arranged downstream of the paper feeder 1. The paper feed conveying section 12 includes a plurality of paper feed roller pairs 36, a paper feed conveying drive section 37, and a plurality of paper sensors 38.

[0044] The paper feed roller pair 36 nip and transport the paper P. A plurality of paper feed roller pairs 36 are arranged along the paper feed path R. The paper feed roller pair 36 is configured to be capable of transporting the paper P in a transport direction D1 by forward rotation drive and to be capable of transporting the paper P in a reverse transport direction D2 by reverse rotation drive.

[0045] The paper feed conveyance drive unit 37 drives the paper feed roller pairs 36 in forward and reverse directions. The paper feed conveyance drive unit 37 includes a motor (not shown) and the like. The paper feed conveyance drive unit 37 is configured to be able to drive each paper feed roller pair 36 independently.

[0046] The paper sensor 38 detects the paper transported along the paper feed path R. A plurality of paper sensors 38 are arranged along the paper feed path R.

[0047] The control unit 13 controls the overall operation of the sheet feeding device 1. The control unit 13 includes a CPU, a RAM, a ROM, a hard disk, and the like.

[0048] The control unit 13 controls the suction conveyance unit 8 and the paper feed conveyance unit 12 to convey the reusable paper P in the reverse conveyance direction D2 and return it from the paper feed conveyance unit 12 to the paper feed tray 2 in a paper recovery process described later.

[0049] Next, the operation of the sheet feeding device 1 will be described.

[0050] When the start of paper feeding is instructed, the control unit 13 starts lifting the paper feed tray 2 from a state in which the top surface of the paper stack PT on the paper feed tray 2 is below the lower limit of the detection range of the upper limit sensor 11.

[0051] After the paper feed tray 2 starts to rise, when the upper end of the paper stack PT on the paper feed tray 2 comes within the detection range of the upper limit sensor 11, the light reflected by the right side surface of the upper end of the paper stack PT begins to be received by the light receiving unit 32 of the upper limit sensor 11. Then, as the paper feed tray 2 rises, the area of ​​the paper stack PT on the paper feed tray 2 that is within the detection range of the upper limit sensor 11 expands, and the sensor value (amount of received light) of the upper limit sensor 11 increases.

[0052] When the control unit 13 determines that the sensor value has reached a predetermined non-floating threshold, it stops the lifting of the paper feed tray 2. Here, the non-floating threshold is set as the sensor value when the height position of the top surface of the paper stack PT is at a predetermined sensor position within the detection range of the upper limit sensor 11. Therefore, by stopping the lifting of the paper feed tray 2 when the sensor value reaches the non-floating threshold as described above, the paper feed tray 2 stops at a height position where the top surface of the paper stack PT is at the above-mentioned sensor position.

[0053] Next, the control unit 13 starts raising or lowering the paper feed tray 2, and when the top surface of the paper stack PT reaches a predetermined paper feed start position, stops the paper feed tray 2. This sets the height position of the top surface of the paper stack PT to the paper feed start position. Here, the control unit 13 determines whether or not the top surface of the paper stack PT has reached the paper feed start position based on the number of output pulses from the encoder 5 from the point when the paper feed tray 2 started to rise or fall.

[0054] The paper feed start position is higher than the target position of the top surface of the paper stack PT during the paper feed operation. Specifically, the paper feed start position is higher than the target position by the thickness of the paper P of the total number of sheets excluded from sampling (described later) and half of the number of sheets sampled (described later).

[0055] Next, the control unit 13 starts the paper feed operation. Specifically, the control unit 13 opens the floating shutter 17, and starts driving the suction mechanism unit 22, the floating fan 16, and the separation fan 18. Here, the suction shutter 30 is open. The control unit 13 also controls the paper feed conveyance drive unit 37 to start driving each of the paper feed roller pairs 36 in the forward direction.

[0056] After the suction mechanism 22, the levitation fan 16, and the separation fan 18 start to operate, as shown in FIG. 3, the multiple sheets of paper P in the levitation area F are levitated by the levitation airflow A1, and the topmost sheet of paper P is adsorbed to the conveying surface 26a of the conveying belt 26 by the suction airflow A3.

[0057] Next, the control unit 13 closes the floating shutter 17. This stops the floating air current A1. As a result, as shown in FIG. 4, the uppermost sheet P is separated from the second and subsequent sheets P by the separation air current A2, and the second and subsequent sheets P fall.

[0058] Next, the control unit 13 starts driving the belt unit 21 in the forward direction. This causes the paper P to be transported by the suction transport unit 8 to the paper feed transport unit 12. The topmost paper P transported by the suction transport unit 8 passes through the gap between the transport surface 26a and the damming member 9 and is transported toward the paper feed transport unit 12. The second and subsequent sheets of paper P from the top are stopped by the damming member 9 and fall.

[0059] The paper P conveyed to the paper feed conveyance section 12 is conveyed to the printing device by a plurality of paper feed roller pairs 36. The control section 13 stops the belt unit 21 after a predetermined driving time has elapsed since the start of normal rotation of the belt unit 21.

[0060] Next, the control unit 13 opens the floating shutter 17 to float the paper P in order to feed the next paper P.

[0061] By repeating the above operation, the paper P is fed in sequence from the paper feeder 1 to the printing device.

[0062] After the start of the paper feed operation, when the number of fed sheets reaches the sampling exclusion number, the control unit 13 starts sampling of the sensor value for determining the tracking threshold value used for tracking control during the paper feed operation.

[0063] Here, the follow-up control is a control for raising the paper feed table 2 in accordance with a decrease in the remaining amount of paper P on the paper feed table 2 due to paper feeding in order to maintain the height position of the upper surface of the paper stack PT on the paper feed table 2 at a target position during paper feeding operation. In the follow-up control, the control unit 13 acquires a sensor value of the paper P floated by the floating unit 6 for each sheet of paper transported by the suction transport unit 8, and raises the paper feed table 2 when the acquired sensor value is less than a follow-up threshold value.

[0064] The sensor value of the paper P floated by the floating portion 6 while it is floating is the amount of reflected light received from the edge surface of the floating paper P within the detection range of the upper limit sensor 11. Therefore, the sensor value of the paper P while it is floating increases as the number of floating sheets of paper P within the detection range of the upper limit sensor 11 increases.

[0065] The number of sheets P that can be floated by the air blown by the floating part 6 is the number of sheets P within the floating area F. Therefore, the lower the height position of the uppermost sheet P (the upper surface of the stack of sheets PT) on the paper feed table 2 when the sheets P on the paper feed table 2 are not floating, the fewer the number of sheets P that can be floated by the air blown by the floating part 6.

[0066] For this reason, the sensor value while the paper P is floating can be used as information indicating the height position of the upper surface of the paper stack PT on the paper feed table 2 in a pseudo manner in the case where the paper P on the paper feed table 2 is not floating. If the height position of the paper feed table 2 does not change, the amount of floating paper P decreases as the paper feeding proceeds, and the sensor value tends to decrease.

[0067] Therefore, in the paper feeder 1, as described above, the sensor value while the paper P is floating is used to perform follow-up control during the paper feed operation.

[0068] The above-mentioned number of sheets excluded from sampling is preset as the number of sheets fed for which sampling of the sensor value for determining the tracking threshold is not performed immediately after the start of the paper feed operation. Immediately after the start of the paper feed operation, the behavior of the paper P when it is floated is unstable, so the number of sheets excluded from sampling is set and sampling of the sensor value is not performed until that number of sheets have been fed. The behavior of the paper P when it is floated differs depending on the paper type (paper thickness), so the number of sheets excluded from sampling is set according to the paper type (paper thickness). The number of sheets excluded from sampling may be one sheet or multiple sheets.

[0069] When the above-mentioned sampling is started, the control unit 13 acquires the sensor value of the upper limit sensor 11 while the paper P is floating up for feeding the next paper P after the last paper P of the number of sheets excluded from sampling. After that, the control unit 13 acquires the sensor value while the paper P is floating up for each sheet of paper transported by the suction transport unit 8. As the sensor value while the paper P is floating up, the control unit 13 acquires, for example, the sensor value after a predetermined time from the time when the floating shutter 17 is opened.

[0070] When the sensor values ​​for the number of samples are acquired, the control unit 13 determines a tracking threshold and starts tracking control. Specifically, the control unit 13 calculates an average value of the sensor values ​​for the acquired number of samples, and determines the calculated average value as the tracking threshold.

[0071] Here, the number of samples is a preset number of sheets to be sampled as the number of sheets fed for sampling the sensor value to determine the tracking threshold value. The number of samples can be a common value regardless of the paper type, etc., or can be changed according to the paper type (paper thickness).

[0072] The sampling period during which the sensor values ​​for the sampling number of sheets are acquired is set so that the same number of sheets are fed both before and after the height position of the top surface of the stack of sheets PT reaches the target position.

[0073] The number of sheets fed before and after the height position of the top surface of the paper stack PT reaches the target position during the sampling period may be different. In this case, for example, the tracking threshold can be determined by adjusting the average value of the sensor value for the number of sampled sheets according to the number of sheets fed before and after the height position of the top surface of the paper stack PT reaches the target position during the sampling period.

[0074] When the tracking threshold is determined, the control unit 13 starts tracking control using the determined tracking threshold. Until the tracking control starts, the height position of the paper feed tray 2 is fixed at the position set at the start of the paper feed operation.

[0075] When the tracking control is started, the control unit 13 raises the paper feed tray 2 for each sheet that is fed if the acquired sensor value is less than the tracking threshold value.

[0076] Specifically, when the acquired sensor value is less than the tracking threshold, the control unit 13 drives the lift motor 4 for a predetermined driving time to raise the paper feed tray 2. At this time, the control unit 13 controls the driving voltage of the lift motor 4 according to the difference between the acquired sensor value and the tracking threshold.

[0077] Specifically, the control unit 13 controls the lift motor 4 to increase the drive voltage as the difference between the sensor value and the tracking threshold increases, thereby increasing the amount of lift of the paper feed tray 2. The greater the difference between the sensor value and the tracking threshold, the fewer sheets of paper P are in the floating area F, and the lower the height position of the top surface of the stack of paper sheets PT on the paper feed tray 2 when the sheets P on the paper feed tray 2 are not floating. For this reason, the control unit 13 controls the lift of the paper feed tray 2 to increase the amount of lift of the paper feed tray 2, the greater the difference between the sensor value and the tracking threshold. The relationship between the difference between the sensor value and the tracking threshold and the drive voltage of the lift motor 4 is preset based on experiments, etc. for each paper type (paper thickness) so that the height position of the top surface of the stack of paper sheets PT reaches a target position as the paper feed tray 2 rises.

[0078] When the feeding of the number of sheets P to be printed has been completed, the control unit 13 stops the suction mechanism unit 22, the levitation fan 16, the separation fan 18, and each pair of paper feed rollers 36, thereby completing the series of paper feeding operations.

[0079] Next, the paper collection process will be described.

[0080] The paper recovery process is a process for recovering reusable paper P from the paper feed conveyance section 12 to the paper feed tray 2 when a jam of the paper P occurs in the paper feed conveyance section 12.

[0081] During the above-mentioned paper feeding operation, if the detection timing of the paper P in at least any one of the paper sensors 38 is delayed from the theoretical value by a threshold value or more, the control unit 13 determines that a jam has occurred in the paper feeding and conveying unit 12. When it is determined that a jam has occurred in the paper feeding and conveying unit 12, the control unit 13 stops the paper feeding operation.

[0082] When the paper feed operation is stopped due to a jam in the paper feed conveying section 12, the paper P upstream of the paper P that caused the jam in the paper feed conveying section 12 is undamaged and can be reused. Therefore, the paper feeder 1 returns reusable paper P to the paper feed tray 2 by a paper recovery process. However, even if the paper P is upstream of the paper P that caused the jam, if the paper P is nipped by the same paper feed roller pair 36 as the paper P that caused the jam, it is not treated as reusable paper P and is not targeted for recovery by the paper recovery process. Here, the control section 13 can determine the position of the paper P when the paper feed operation is stopped due to a jam and which paper P caused the jam, based on the timing of detection of the paper P by the paper sensor 38.

[0083] When the paper feed operation is stopped due to the occurrence of a jam in the paper feed conveyance section 12, if there is reusable paper P in the paper feed conveyance section 12 (on the paper feed path R), the control section 13 executes a paper recovery process.

[0084] Fig. 5 is a flow chart of the paper collection process. In step S1 of Fig. 5, the suction mechanism unit 22 starts to be driven. Here, the suction shutter 30 is opened. In addition, the control unit 13 sets the height position of the upper surface of the paper stack PT to a predetermined receiving position.

[0085] Here, the receiving position is preset as the height position of the upper surface of the paper stack PT during paper recovery processing. The receiving position is set as close as possible to the conveying surface 26a of the suction conveying unit 8 in order to prevent the paper P that has fallen from the suction mechanism unit 22 due to the closing of the suction shutter 30 in step S4 described later from leaning against the damming member 9 or becoming slanted. Specifically, the receiving position is located lower than and near the upper end of the damming member 9, and is higher than the target position described above during the paper feeding operation.

[0086] The control unit 13 starts lifting the paper feed tray 2, and when the number of output pulses from the encoder 5 from the start of lifting the paper feed tray 2 reaches the number of pulses for the distance from the target position to the receiving position, the control unit 13 stops the paper feed tray 2. As a result, the height position of the top surface of the paper stack PT is set to the receiving position.

[0087] Next, in step S2, the control unit 13 starts reverse driving of the paper feed roller pair 36 and the belt unit 21. Here, the control unit 13 starts reverse driving of each of the paper feed roller pairs 36 necessary to transport the paper P remaining in the paper feed transport unit 12, the paper P furthest upstream in the transport direction D1, toward the paper feed table 2, among the multiple paper feed roller pairs 36 in the paper feed transport unit 12.

[0088] As a result, of the reusable sheets P to be collected, the sheet P furthest upstream in the conveying direction D1 starts to be conveyed in the reverse conveying direction D2 by the sheet feed roller pair 36. When the rear end of the sheet P conveyed in the reverse conveying direction D2 by the sheet feed roller pair 36 when conveyed in the conveying direction D1 (the leading end when conveyed in the reverse conveying direction D2) reaches the guide surface 10a of the induction guide 10, the sheet P advances along the guide surface 10a and is guided to the conveying surface 26a of the suction conveying unit 8, as shown in FIG.

[0089] When the rear end of the paper P being transported in the reverse transport direction D2 (the leading end when transported in the reverse transport direction D2) reaches the transport surface 26a, a part of the paper P is adsorbed to the transport surface 26a. After that, the paper P is transported in the reverse transport direction D2 by the adsorption transport unit 8 and the paper feed roller pair 36 until the leading end of the paper P (the trailing end when transported in the reverse transport direction D2) passes through the upstreammost paper feed roller pair 36 in the transport direction D1.

[0090] Here, in the paper recovery process, the control unit 13 controls the conveying speed of the paper P by the suction conveying unit 8 to be faster than the conveying speed of the paper P by the paper feed roller pair 36. This allows the paper P to be conveyed in the reverse conveying direction D2 with the slack in the paper P eliminated.

[0091] After starting to transport the paper sheet P in the reverse transport direction D2, in step S3, the control unit 13 determines whether or not the rear end of the paper sheet P (the leading end when transported in the reverse transport direction D2) has reached the end fence 3. Here, the control unit 13 determines whether or not the rear end of the paper sheet P has reached the end fence 3 based on the elapsed time since the leading end of the paper sheet P (the trailing end when transported in the reverse transport direction D2) was detected by the paper sensor 38 most upstream in the transport direction D1. If it is determined that the rear end of the paper sheet P has not reached the end fence 3 (step S3: NO), the control unit 13 repeats step S3.

[0092] In addition, an encoder may be connected to the motor of the paper feed conveying drive unit 37, which drives the upstreammost paper feed roller pair 36 in the conveying direction D1, and the control unit 13 may determine whether the rear end of the paper P has reached the end fence 3 based on the number of output pulses from this encoder.

[0093] If it is determined that the rear end of the paper P has reached the end fence 3 (step S3: YES), then in step S4, the control unit 13 stops the pair of paper feed rollers 36 and the belt unit 21. The control unit 13 also closes the suction shutter 30. As a result, when the rear end of the paper P reaches the end fence 3 as shown in FIG. 7, the transport of the paper P in the reverse transport direction D2 is stopped. Also, the suction of the paper P to the suction transport unit 8 is released, and the paper P falls onto the paper stack PT on the paper feed table 2. As a result, the paper P is collected on the paper feed table 2.

[0094] The transport of the paper P in the reverse transport direction D2 may be stopped at the point in time when the paper P has been transported a predetermined transport amount after the rear end of the paper P reaches the end fence 3. In this case, the transport amount after the rear end of the paper P reaches the end fence 3 may be changeable.

[0095] Next, in step S5, the control unit 13 determines whether or not there is a next sheet P to be collected in the paper feed conveyance unit 12. Here, as described above, even if a sheet P is located upstream of the sheet P that caused the jam, the sheet P that is nipped by the same sheet feed roller pair 36 as the sheet P that caused the jam is not a target for collection.

[0096] If it is determined that there is the next paper P to be collected (step S5: YES), in step S6, the control unit 13 opens the suction shutter 30. The control unit 13 also lowers the paper feed tray 2 by the number of sheets of paper. Here, the control unit 13 controls the amount of lowering of the paper feed tray 2 based on the number of output pulses from the encoder 5 from the start of the lowering of the paper feed tray 2. After this, the control unit 13 returns to step S2.

[0097] If it is determined that there is no next paper P to be collected (step S5: NO), in step S7, the control unit 13 stops the suction mechanism unit 22 and opens the suction shutter 30. This ends the paper collection process.

[0098] After the paper collection process, the paper P remaining in the paper feed conveyance section 12, such as the paper P that caused the jam, is removed by the user through the operation of clearing the jam.

[0099] As described above, in the paper feeding device 1, the control unit 13 controls the suction conveying unit 8 and the paper feed conveying unit 12 in the paper recovery process to convey the reusable paper P in the reverse conveying direction D2 and return it from the paper feed conveying unit 12 to the paper feed tray 2. This makes it possible to reduce the amount of paper P remaining in the paper feed conveying unit 12. This makes it possible to reduce the effort required to clear jams and the amount of paper P that is wasted.

[0100] Furthermore, the paper feeding device 1 includes an induction guide 10 that guides the paper P transported in the reverse transport direction D2 from the paper feed transport section 12 toward the paper feed tray 2 during the paper recovery process to the transport surface 26a of the suction transport section 8. This allows the paper recovery process to be performed even if the damming member 9 is immovable (fixed), without the damming member 9 interfering with the paper P transported in the reverse transport direction D2. Furthermore, because the damming member 9 is immovable, it is possible to prevent the damming member 9 from rubbing against the paper P (paper stack PT) on the paper feed tray 2 and generating paper dust.

[0101] Therefore, according to the paper feeding device 1, it is possible to reduce the effort required to clear a jam and the amount of paper P that is wasted, while suppressing the generation of paper powder (dust).

[0102] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

[0103] [Note] This application discloses the following inventions.

[0104] (Appendix 1) A loading platform on which a sheet stack is loaded; a floating unit that blows air onto the sheet stack to float a plurality of sheets from the sheet stack; a first conveying section that conveys a topmost sheet of the plurality of sheets floated by the floating section while holding the topmost sheet on a conveying surface; a non-movable blocking member that blocks sheets other than the uppermost sheet transported by the first transport unit; a second conveying section disposed downstream of the blocking member in a conveying direction of the uppermost sheet by the first conveying section, and configured to convey the sheet conveyed by the first conveying section to a downstream side in the conveying direction; a guide disposed between the blocking member and the second conveying unit, the guide guiding the sheet conveyed from the second conveying unit to the stacking table in a direction opposite to the conveying direction to the conveying surface of the first conveying unit; a control unit that controls the first conveying unit and the second conveying unit to convey the reusable sheet in a direction opposite to the conveying direction and return the reusable sheet from the second conveying unit to the stacking table when a sheet jam occurs in the second conveying unit; A sheet feeding device comprising: [Explanation of symbols]

[0105] 1 Paper feeder 2 Paper feed tray 3 End Fence 4 Lifting motor 5 Encoders 6 Floating part 7 Separation part 8. Suction and transport section 9. Damming members 10 Guidance 10a Guide surface 11 Upper limit sensor 12 Paper feed transport section 13 Control section 16 Levitation Fan 17 Floating Shutter 18 Separate Fan 21 Belt unit 22 Suction mechanism section 26 Conveyor belt 26a Conveying surface 27 Drive roller 28 Driven roller 29 Transport motor 30 Suction shutter 31 Light emitting part 32 Light receiving part 36 Paper feed roller pair 37 Paper feed transport drive unit 38 Paper Sensor P paper PT paper stack

Claims

[Claim 1] A loading platform on which a sheet stack is loaded; a floating unit that blows air onto the sheet stack to float a plurality of sheets from the sheet stack; a first conveying section that conveys a topmost sheet of the plurality of sheets floated by the floating section while holding the topmost sheet on a conveying surface; a non-movable blocking member that blocks sheets other than the uppermost sheet transported by the first transport unit; a second conveying section that is disposed along a path along which the sheets are conveyed downstream of the blocking member in a conveying direction of the uppermost sheet by the first conveying section, and that has a plurality of roller pairs that nip the sheet conveyed by the first conveying section and convey the sheet downstream in the conveying direction; a guide disposed between the blocking member and the second conveying unit, the guide guiding the sheet conveyed from the second conveying unit toward the stacking table in a direction opposite to the conveying direction to the conveying surface of the first conveying unit; a control unit that controls the first conveying unit and the second conveying unit to convey, in the case where a sheet jam occurs in the second conveying unit, a reusable sheet that is located upstream in the conveying direction from the sheet that caused the jam and is not nipped by the same roller pair as the sheet that caused the jam when a sheet jam occurs in the second conveying unit and a sheet that is reusable is conveyed in a direction opposite to the conveying direction and returned from the second conveying unit to the stacking table when a sheet supply operation is stopped due to the occurrence of the jam; A sheet feeding device comprising:

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