Sheet feeding device

Abstract

To provide a sheet feeding device capable of suppressing sheet separation failure.SOLUTION: The sheet feeding device includes: a sheet supporting section that supports a sheet; an air blowing section that blows air onto a downstream end in a sheet feeding direction of the sheet supported on the sheet supporting section; a feeding belt that feeds the uppermost sheet among the sheets onto which air has been blown by the air blowing section while sucking it; and an upstream suction section that is disposed upstream of the feeding belt in the sheet feeding direction and sucks the uppermost sheet. The air blowing section includes: a first blowing section that blows air in the width direction of the sheet supported on the sheet supporting section from one side in the width direction of the sheet; and a second blowing section that blows air from downstream to upstream in the sheet feeding direction at the sheet supported on the sheet supporting section.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, an air feeder has been disclosed that includes a sheet tray, a blower that floats sheets loaded on the sheet tray with air, and a sheet transport section that attracts and transports the floated sheets. The sheet transport section has a first sheet suction section, a second sheet suction section, and a transport belt that covers the first and second sheet suction sections, and the sheets are attracted to the transport belt by the suction forces of the first sheet suction section and the second sheet suction section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-199437 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the printing industry has been in demand for printing machines and printers capable of printing on various media sheets on demand. Media sheets include different types of paper, such as plain paper and coated paper, and range from thin paper with a low basis weight and low rigidity to thick paper with a high basis weight and high rigidity. In addition, cut paper that has been cut to a predetermined size in advance is used for the above media sheets due to its ease of handling, and the cut sizes vary from small to large.

[0005] In the case of an air feeder as described in Patent Document 1, for example, when feeding long sheets or sheets that stick closely to each other, it is necessary to reliably separate the top sheet from the sheet below it. If the top sheet and the sheet below it stick closely to each other, the air sent from the blower to the leading edge of the sheet may not reach the trailing edge of the sheet and may escape in the width direction of the sheet midway, which may cause poor separation of the sheets.

[0006] SUMMARY OF THE DISCLOSURE An object of the present invention is to provide a sheet feeding device capable of suppressing sheet separation failure. [Means for solving the problem]

[0007] The present invention is characterized in that the sheet feeding device comprises a sheet supporting section that supports a sheet, an air blowing section that blows air onto a downstream end in a sheet feeding direction of the sheet supported by the sheet supporting section, a feeding belt that feeds the uppermost sheet among the sheets onto which air has been blown by the air blowing section while sucking it, and an upstream suction section that is arranged upstream of the feeding belt in the sheet feeding direction and sucks the uppermost sheet. Effect of the Invention

[0008] According to the present invention, poor separation of the sheets can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall schematic diagram showing a printer according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 4A is a perspective view showing a feeding unit, and FIG. 4B is an enlarged view showing a plurality of holes formed in a separation belt. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a block diagram showing a control block of a feeding module. [Figure 7] 11 is a flowchart showing a feeding operation. [Figure 8] 13 is a flowchart showing control for changing the suction force and suction timing of the second suction unit 1670. [Figure 9] FIG. 13A is a bottom view showing a feeding unit according to a second embodiment, and FIG. 13B is an enlarged view showing a plurality of long holes provided in a chamber guide. [Figure 10] FIG. 13 is a perspective view showing a second suction unit according to a third embodiment. [Figure 11] FIG. 13 is a perspective view showing a second suction unit according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present embodiment will be described below with reference to the drawings. Note that the embodiment described below is a preferred embodiment of the present invention, and various technically preferable limitations are attached, but the scope of the present invention is not unduly limited by the following explanation, and all of the configurations described in the present embodiment are not essential constituent elements of the present invention.

[0011] <First embodiment> [Outline of the inkjet recording system] In the first embodiment, a case where an image forming system is applied to an inkjet recording system 1 is described. FIG. 1 is a schematic diagram showing an example of a schematic configuration of the inkjet recording system 1. The inkjet recording system 1 is a sheet-fed inkjet recording system that produces a recorded matter by forming an ink image on a sheet using two liquids, a reaction liquid and an ink. As shown in FIG. 1, the inkjet recording system 1 is composed of a feeding module 100, a print module 200, a drying module 300, a fixing module 400, a cooling module 500, an inversion module 600, and a discharge module 700. A cut-paper-like sheet supplied from the feeding module 100 is conveyed along a conveying path, processed in each module, and discharged from the discharge module 700. The sheet in this embodiment includes paper such as paper and envelopes, plastic films such as overhead projector sheets (OHP), and cloth.

[0012] A feeding module 100, which is an example of a sheet feeding device, has three storages 110a, 110b, and 110c that store sheets. Each storage 110a, 110b, and 110c is configured to be able to be pulled out to the front side of the device. Sheets are fed one by one in each storage 110a, 110b, and 110c by a feeding unit (160a, 160b, and 160c) and transported to a print module 200. The number of storages 110a, 110b, and 110c is not limited to three, and may be one, two, or four or more.

[0013] The print module 200 has a pre-imaging registration correction unit (not shown), a print belt unit 220, and a recording unit 230. The sheet conveyed from the feed module 100 has its inclination and position corrected by the pre-imaging registration correction unit, and is conveyed to the print belt unit 220. The recording unit 230 is disposed at a position facing the print belt unit 220 with respect to the conveying path. The recording unit 230 is a sheet processing unit that performs recording processing (printing) on ​​the conveyed sheet from above with a recording head to form an image. A plurality of recording heads are arranged along the conveying direction. In this embodiment, in addition to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), a total of five line-type recording heads corresponding to the reaction liquid are provided. Note that the number of colors and the number of recording heads are not limited to five.

[0014] The inkjet method may employ a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, or the like. Ink of each color is supplied to the recording head from an ink tank (not shown) via an ink tube. The sheet printed by the recording unit 230 is attracted and conveyed by the print belt unit 220, so that the sheet is conveyed while ensuring a clearance with the recording head. The sheet printed by the recording unit 230 is subjected to detection of misalignment and color density of the image formed on the sheet by an in-line scanner (not shown) arranged downstream of the recording unit in the sheet conveying direction. The detection result is used to correct the printed image.

[0015] The drying module 300 has a decoupling section 320, a drying belt unit 330, and a hot air blowing section 340, and reduces the liquid content contained in the ink applied to the sheet by the recording section 230 of the print module 200, thereby improving the fixation of the sheet and the ink. The sheet printed by the recording section 230 of the print module 200 is transported to the decoupling section 320 arranged on the upstream side of the drying module 300 in the sheet transport direction. The decoupling section 320 can transport the sheet from above by air pressure and friction of the belt, and by weakly holding and transporting the sheet on the belt, it prevents the sheet on the print belt unit 220 where the ink image is formed from shifting. The drying belt unit 330 is arranged below the belt, and the hot air blowing section 340 is arranged above the belt, facing each other with the belt in between.

[0016] The sheet conveyed from the decoupling section 320 is adsorbed and conveyed by the drying belt unit 330, and at the same time, the ink-applied surface is dried by receiving hot air from the hot air blowing section 340. Note that the drying method may be a combination of a method of applying hot air, a method of irradiating the sheet surface with electromagnetic waves (ultraviolet rays, infrared rays, etc.), and a conductive heat transfer method by contact with a heating element.

[0017] The fixing module 400 has a fixing belt unit 410. The fixing belt unit 410 has an upper belt unit and a lower belt unit, and the sheet conveyed from the drying module 300 passes between the heated upper belt unit and lower belt unit, thereby fixing the ink to the sheet.

[0018] The cooling module 500 has a plurality of cooling sections 510, and cools the high-temperature sheet transported from the fixing module 400. The cooling sections 510 are configured to take in outside air into a cooling box with a fan, increase the pressure inside the cooling box, and cool the sheet by blowing air from nozzles formed in a transport guide onto the sheet. The cooling sections 510 are disposed both above and below the transport path, and cool the sheet from both sides.

[0019] The cooling module 500 also has a conveying path switching unit, and can switch the sheet conveying path depending on whether the sheet is conveyed to the inversion module 600 or to a double-sided conveying path used for double-sided printing. During double-sided printing, the sheet is conveyed to a conveying path below the cooling module 500. In this case, the sheet is further conveyed from the cooling module 500 along a double-sided conveying path of the fixing module 400, the drying module 300, the print module 200, and the feeding module 100. The double-sided conveying path of the fixing module 400 is provided with a first inversion unit 420 that inverts the sheet. Then, the sheet is conveyed again from the feeding module 100 to the pre-imaging registration correction unit of the print module 200, the print belt unit 220, and the recording unit 230, where it is printed.

[0020] The inversion module 600 has a second inversion section 640, and can invert the front and back of the conveyed sheet, and can change the front and back orientation of the discharged sheet. The discharge module 700 has a top tray 720 and a stacking section 750, and aligns and stacks the sheets conveyed from the inversion module 600.

[0021] [Feeding module] Next, the configuration of the feeding module 100 will be described in detail. The sheets stored in the above-mentioned three storages 110a, 110b, and 110c provided in the feeding module 100 are fed by the feeding units 160a, 160b, and 160c corresponding to the storages 110a, 110b, and 110c, respectively. Since the storages 110a, 110b, and 110c and the feeding units 160a, 160b, and 160c have the same configuration, the storage 110a, the feeding unit 160a, and the peripheral configurations thereof will be described in detail below. Note that the storages 110a, 110b, and 110c and the feeding units 160a, 160b, and 160c do not all need to have the same configuration. For example, the maximum number of sheets that can be stored in the storages 110a, 110b, and 110c and the size of the sheets may be different from each other.

[0022] 2, the storage 110a has a main body 1110, a lifter plate 1140 supported by the main body 1110, a front end guide 1131, a rear end guide 1130, a first side guide 1121, and a second side guide 1122. The lifter plate 1140 as a sheet support section supports a sheet and is suspended by a lifter wire 1141. The lifter wire 1141 is wound or unwound by a wire pulley 1142 driven by a motor (not shown), so that the lifter plate 1140 can move up and down while maintaining the sheet in a horizontal state.

[0023] The leading edge guide 1131 regulates the leading edge of the sheets stacked on the lifter plate 1140, i.e., the downstream edge in the sheet feeding direction D1. The trailing edge guide 1130 regulates the trailing edge of the sheets stacked on the lifter plate 1140, i.e., the upstream edge in the sheet feeding direction D1. The first side guide 1121 and the second side guide 1122 are configured to be movable in a width direction W perpendicular to the sheet feeding direction D1, and regulate the edge position in the width direction W of the sheets stacked on the lifter plate 1140. The storage 110a is configured to be detachable in the width direction W from the housing of the feeding module 100, and is pulled out to the first side guide 1121 side in the width direction W and attached to the second side guide 1122 side.

[0024] FIG. 3(a) is a perspective view showing the feeding unit 160a and its surrounding configuration, and FIG. 3(b) is an enlarged view showing a plurality of holes 1610a formed in the separation belt 1610. FIG. 4 is a cross-sectional view showing the feeding unit 160a. The feeding unit 160a floats the sheets from the end face in the width direction of the sheet stack with handling air, adsorbs the sheets to the separation belt 1610 with negative pressure suction air, and separates the sheets into individual sheets with separation air blown from the leading end of the sheet stack. The feeding unit 160a employs a full air feeding method in which the sheets are fed one by one by rotating the separation belt 1610 without using rollers for separating the sheets.

[0025] As shown in FIGS. 3(a) and 4, the feeding unit 160a has a separating air unit 170, a separating air unit 180, a first suction unit 1600, a separating belt 1610, a second suction unit 1670, and a driving roller unit 1700.

[0026] 3(a), the sorting air unit 170 as the first blowing section has a side fan 1651 whose rotation speed can be controlled, a side duct 1652, a side nozzle 1653, and a side fan valve 1654. A cylindrical side duct 1652 is connected to the side fan 1651, and a side nozzle 1653 is provided at the tip of the side duct 1652. The side duct 1652 and the side nozzle 1653 are provided at the rear side of the storage 110a and at the downstream end in the sheet feeding direction D1.

[0027] Air sent from the side fan 1651 (hereinafter referred to as "cleaning air") passes through the side duct 1652 and is discharged from the side nozzle 1653. The side duct 1652 is configured to be movable in the width direction W in conjunction with the second side guide 1122 (see FIG. 2). As a result, the side nozzle 1653 from which the cleaning air is discharged is disposed near and behind the leading ends of the sheets stacked in the storage 110a.

[0028] The side fan valve 1654 is provided between the side fan 1651 and the side duct 1652, and is configured to be openable and closable by a side fan valve solenoid 1655. By controlling the opening and closing of the side fan valve 1654, the timing of blowing the cleaning air can be controlled.

[0029] The separation air unit 180 has a front fan 1661, a front duct 1662, a front nozzle 1663, and a front fan valve 1664. A cylindrical front duct 1662 is connected to the front fan 1661, and a front nozzle 1663 is provided at the tip of the front duct 1662. The front duct 1662 and the front nozzle 1663 are provided at the downstream end of the storage 110a in the sheet feeding direction D1.

[0030] Air sent from the front fan 1661 (hereinafter referred to as separation air) passes through a front duct 1662 and is discharged from a front nozzle 1663. The front nozzle 1663 from which the separation air is discharged is disposed toward the separation belt 1610 above the sheets loaded in the storage 110a.

[0031] The front fan valve 1664 is provided between the front fan 1661 and the front duct 1662, and is configured to be openable and closable by a front fan valve solenoid 1665. By controlling the opening and closing of the front fan valve 1664, the blowing timing of the separation air can be controlled.

[0032] The above-mentioned separating air unit 170 and separating air unit 180 constitute an air blowing section 800 that blows air onto the downstream end of the sheet supported by the lifter plate 1140 in the sheet feeding direction D1.

[0033] The first suction unit 1600 has a first suction fan 1601, a first suction chamber 1602, and a first suction fan valve 1603. The first suction chamber 1602 is connected to the first suction fan 1601 and has a space therein. The first suction chamber 1602 has an opening 1602a at a position facing the sheets stacked in the storage 110a, and the opening 1602a communicates with the internal space of the first suction chamber 1602. The first suction fan 1601 can generate negative pressure in the internal space of the first suction chamber 1602.

[0034] The first suction fan valve 1603 is provided between the first suction fan 1601 and the first suction chamber 1602, and is configured to be openable and closable by a first suction fan valve solenoid 1605. When the first suction fan valve 1603 is opened while the first suction fan 1601 is driven, the inside of the first suction chamber 1602 becomes negative pressure.

[0035] 4, a separation belt 1610 is disposed around the first suction chamber 1602, and the separation belt 1610 as a feeding belt is wound around a belt driving roller 1612 and a belt driven roller 1613. The belt driving roller 1612 is driven by a belt driving motor 1614 (see FIG. 6), whereby the separation belt 1610 rotates, and the belt driven roller 1613 rotates following the separation belt 1610.

[0036] As shown in FIG. 3(b), the separation belt 1610 is provided with a plurality of circular holes 1610a, and the circular holes 1610a located on the lower surface side of the separation belt 1610 communicate with the opening 1602a of the first suction chamber 1602. Therefore, when the internal space of the first suction chamber 1602 becomes negative pressure, the air around the separation belt 1610 can be sucked toward the inside of the first suction chamber 1602 through the opening 1602a and the plurality of holes 1610a of the separation belt 1610. When a sheet is present near the lower surface of the separation belt 1610, the sheet is adsorbed to the separation belt 1610. The plurality of holes 1610a have an edge portion 1610b on the upstream side in the sheet feeding direction D1. The edge portion 1610b extends so as to intersect with the sheet feeding direction D1, which is the moving direction of the separation belt 1610. When the separation belt 1610 is driven with the sheet adsorbed thereto, the separation belt 1610 conveys the sheet by biting the sheet with the edge portions 1610b of the multiple holes 1610a. This allows the separation belt 1610 to reliably convey the sheet.

[0037] 4, the drive roller unit 1700 is disposed downstream of the separation belt 1610 in the sheet feeding direction D1, and includes a drive roller 1710 and a driven roller 1720. The drive roller 1710 is driven by a motor (not shown), and the driven roller 1720 rotates following the drive roller 1710. The sheet S fed while being sucked by the separation belt 1610 is transported by the drive roller unit 1700.

[0038] As shown in FIG. 3(a) and FIG. 4, the second suction unit 1670 as an upstream suction section is disposed upstream of the separation belt 1610 in the sheet feeding direction D1. The second suction unit 1670 has a second suction fan 1671, a second suction chamber 1672, and a second suction fan valve 1674. The second suction chamber 1672 is connected to the second suction fan 1671 and has a space therein. The second suction chamber 1672 has an opening 1672a at a position facing the sheets stacked in the storage 110a, and the opening 1672a communicates with the internal space of the second suction chamber 1672. The second suction fan 1671 as a fan can generate negative pressure in the internal space of the second suction chamber 1672.

[0039] The second suction fan valve 1674 is provided between the second suction fan 1671 and the second suction chamber 1672, and is configured to be openable and closable by a second suction fan valve solenoid 1675. When the second suction fan valve 1674 is opened while the second suction fan 1671 is driven, the inside of the second suction chamber 1672 becomes negative pressure.

[0040] A chamber guide 1676 is attached to the second suction chamber 1672 so as to cover the opening 1672a, and a plurality of circular holes 1676a are provided in the chamber guide 1676 as a guide member. The plurality of holes 1676a of the chamber guide 1676 are connected to the opening 1672a of the second suction chamber 1672. Therefore, when the internal space of the second suction chamber 1672 becomes negative pressure, it becomes possible to suck air around the chamber guide 1676 toward the inside of the second suction chamber 1672 through the opening 1672a and the plurality of holes 1676a of the chamber guide 1676. If a sheet is present near the lower surface of the chamber guide 1676, the sheet floats up toward the chamber guide 1676.

[0041] Between the separation belt 1610 and the chamber guide 1676 in the sheet feeding direction D1, a sheet detection sensor 1620 and a sheet detection flag 1620a, a sheet presence / absence detection sensor 1621 and a sheet presence / absence detection flag 1621a are arranged.

[0042] Fig. 5 is a view of the feeding unit 160a as viewed from the upstream side in the sheet feeding direction D1. In Fig. 5, a conveying center 1622 is the center in the width direction W of the sheet S fed from the storage 110a, and is also the center in the width direction W of the conveying path along which the sheet S is conveyed. In addition, the conveying center 1622 is the center in the width direction W of the first side guide 1121 and the second side guide 1122.

[0043] 5, the sheet detection sensor 1620 and the sheet detection flag 1620a are disposed on one side of the conveying center 1622 in the width direction W. The sheet presence / absence detection sensor 1621 and the sheet presence / absence detection flag 1621a are disposed on the other side of the conveying center 1622 in the width direction W. The sheet detection flag 1620a as a first pressing portion hangs down toward the uppermost sheet of the sheets S stacked on the lifter plate 1140, and contacts the surface of the uppermost sheet when the sheets are fed.

[0044] The sheet detection sensor 1620 as a first detection unit detects the height of the uppermost sheet supported by the lifter plate 1140 based on the position of the sheet detection flag 1620a. The sheet detection flag 1620a rotates from a non-detection position to a detection position by contacting the uppermost sheet on the lifter plate 1140. When the sheet detection flag 1620a is in the detection position, the sheet detection sensor 1620 is in a detection state (ON). Even if there is no sheet on the lifter plate 1140, as long as the lifter plate 1140 is at a predetermined height, the sheet detection flag 1620a is held in the detection position by contacting the lifter plate 1140. Therefore, the sheet detection sensor 1620 maintains the detection state (ON).

[0045] Also, the sheet presence / absence detection flag 1621a as the second pressing part hangs down toward the top sheet of the sheets S stacked on the lifter plate 1140, and contacts the surface of the top sheet during sheet feeding. The sheet presence / absence detection sensor 1621 as the second detection part detects the presence or absence of a sheet supported by the lifter plate 1140 based on the position of the sheet presence / absence detection flag 1621a. The sheet presence / absence detection flag 1621a rotates from the non-detection position to the detection position by contacting the top sheet on the lifter plate 1140. When the sheet presence / absence detection flag 1621a is in the detection position, the sheet presence / absence detection sensor 1621 is in a detection state (ON). Also, when there is no sheet on the lifter plate 1140 and the lifter plate 1140 is at a predetermined height, the sheet presence / absence detection flag 1621a falls into an opening formed in the lifter plate 1140, and rotates from the detection position to the non-detection position. Therefore, the sheet presence / absence detection sensor 1621 is in a non-detecting state (OFF).

[0046] The sheet detection flag 1620a and the sheet presence / absence detection flag 1621a are disposed at positions corresponding to the vicinity of the rear end of a sheet of the minimum size that can be conveyed by the feeding unit 160a. The sheet detection flag 1620a and the sheet presence / absence detection flag 1621a are disposed approximately symmetrically with respect to the conveyance center 1622 in the width direction W.

[0047] The sheet detection flag 1620a and the sheet presence / absence detection flag 1621a are provided with weights so that they do not easily float up even if separation air flows in between the uppermost sheet and the sheet below it.

[0048] As shown in FIG. 3(a), the separation belt 1610 has a first suction area AR1 provided with a plurality of holes 1610a capable of sucking the sheet, and the chamber guide 1676 also has a second suction area AR2 provided with a plurality of holes 1676a capable of sucking the sheet. The first suction area AR1 and the second suction area AR2 face the uppermost sheet stacked on the lifter plate 1140. In the width direction W, the distance L3 between the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a is wider than the width L1 of the first suction area AR1 and the width L2 of the second suction area AR2. Therefore, the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a do not interfere with the suction of the sheet. In the width direction W, the width L2 of the second suction area AR2 is narrower than the width L1 and is equal to or smaller than the distance L3.

[0049] [Control Block] 6 is a block diagram showing a control block of the feeding module 100. The feeding module 100 has a media operation unit 1800 capable of inputting sheet information 1820, which is information relating to the sheets to be fed, and a control unit 1801. Note that the media operation unit 1800 and the control unit 1801 may be disposed anywhere within the inkjet recording system 1, not limited to the feeding module 100.

[0050] The media operation unit 1800 is composed of physical buttons, a liquid crystal panel, etc. The sheet information 1820 includes a sheet size 1820a, a sheet basis weight 1820b which is the weight per unit area of ​​the sheet, and a sheet type 1820c which is the type of sheet such as plain paper, coated paper, synthetic paper, and PET sheet. The control unit 1801 has a CPU 1802, a ROM 1803, and a RAM 1804. Various programs are stored in the ROM 1803, and the CPU 1802 reads out and executes these programs. The RAM 1804 is used as a working area for the CPU 1802.

[0051] The control unit 1801 is connected to an environment sensor 1623, a sheet detection sensor 1620, and a sheet presence / absence detection sensor 1621. The environment sensor 1623 (see FIG. 3(a)) can detect the humidity in the storage 110a, that is, the ambient humidity 1820d which is the humidity around the lifter plate 1140. The environment sensor 1623 may detect not only the ambient humidity 1820d but also the ambient temperature, etc.

[0052] The sheet information 1820 and the ambient humidity 1820d make it possible to estimate the time required for separation of the fed sheets, the ease of separation, and the like. Therefore, the control unit 1801 sets optimal sheet feeding conditions 1004 based on the sheet information 1820 and the ambient humidity 1820d. The feeding conditions 1004 include the sheet feeding interval, the feeding speed, and the rotation speeds of the side fan 1651, the front fan, the first suction fan 1601, and the second suction fan 1671.

[0053] For example, for sheets with a large basis weight or size, the weight of each sheet is heavy, so it is preferable to increase the rotation speed of each fan. On the other hand, for sheets with a small basis weight or size, the weight of each sheet is light, so if the rotation speed of each fan is increased, the sheets will flutter, causing poor conveyance and skewing. For this reason, it is preferable to reduce the rotation speed of each fan for sheets with a small basis weight or size. In addition, for types of sheets that tend to stick to each other, particularly in a high humidity environment, the sheets can be stably separated and fed by increasing the rotation speed of each fan or widening the feeding interval.

[0054] The control unit 1801 controls the side fan 1651, the side fan valve solenoid 1655, the front fan 1661, the front fan valve solenoid 1665, the first suction fan 1601, the first suction fan valve solenoid 1605, the second suction fan 1671, the second suction fan valve solenoid 1675, and the belt drive motor 1614 based on the set feeding conditions 1004.

[0055] [Feeding operation] Next, a description will be given of the feeding operation by the feeding module 100. Fig. 7 is a flow chart showing the feeding operation. After setting the feeding conditions 1004, the control unit 1801 starts the feeding operation.

[0056] First, as a feeding preparation operation, the control unit 1801 rotates the side fan 1651, the front fan 1661, the first suction fan 1601, and the second suction fan 1671 at rotation speeds based on the feeding conditions 1004. At this time, the side fan valve solenoid 1655, the front fan valve solenoid 1665, the first suction fan valve solenoid 1605, and the second suction fan valve solenoid 1675 are closed.

[0057] When each fan reaches a predetermined rotation speed, the control unit 1801 sends a feeding start signal and the feeding operation starts. As shown in Fig. 7, the control unit 1801 first opens the side fan valve 1654 by turning on the side fan valve solenoid 1655 (step S1). Then, the loosening air generated by the side fan 1651 is blown from the side nozzle 1653 to a plurality of sheets, including the top sheet, of the sheet stack stacked on the lifter plate 1140. The loosening air is blown in the width direction W from one side in the width direction W toward the leading edge and side edge of the sheets. This loosening air lifts up the top and leading edge end of the sheet stack.

[0058] Next, the control unit 1801 turns on the first suction fan valve solenoid 1605 to open the first suction fan valve 1603 (step S2). This creates a negative pressure in the internal space of the first suction chamber 1602. Then, air is sucked from the multiple holes 1610a of the separation belt 1610 arranged around the first suction chamber 1602, and the topmost sheet floated by the separating air is sucked onto the separation belt 1610.

[0059] Also, at approximately the same timing as step S2, the control unit 1801 turns on the front fan valve solenoid 1665 to open the front fan valve 1664 (step S3). As a result, separation air generated by the front fan 1661 is blown from the front nozzle 1663 to a plurality of sheets, including the top sheet, of the sheet stack stacked on the lifter plate 1140. The separation air is blown to the leading edge of the sheet from downstream to upstream in the sheet feeding direction D1.

[0060] Then, when the top sheet is sucked onto the separation belt 1610, separation air is blown between the top sheet and the sheet directly below it (hereinafter referred to as the lower sheet), separating the top sheet and the lower sheet. Here, in order to reliably separate the top sheet and the lower sheet and feed only the top sheet, it is necessary to flow separation air from the leading edge to the trailing edge of the top sheet.

[0061] While the leading edge of the top sheet is sucked by the separation belt 1610, the lower sheets fall by gravity when the force of the separating air to lift them is lost. This creates a gap between the top sheet and the lower sheets, and if separation air is blown into the gap, the separation air can easily flow from the leading edge to the trailing edge of the top sheet. In addition, the width of the front nozzle 1663 in the width direction W is approximately the same as the width L1 of the first suction area AR1. This allows the separation air to flow efficiently toward the underside of the top sheet sucked into the first suction area AR1.

[0062] While the first suction area AR1 is disposed substantially in the center of the sheet conveying area in the width direction W, the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a are disposed outside the first suction area AR1 in the width direction W. The sheet detection flag 1620a and the sheet presence / absence detection flag 1621a press the top sheet from above. Therefore, the separation air that flows directly below the first suction area AR1 passes through a tunnel-shaped space formed between the top sheet and the lower sheet by the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a. Since the space through which the separation air passes is restricted in the width direction W by the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a, the separation air is more likely to reach the upstream side in the sheet feeding direction D1.

[0063] In addition, in this embodiment, as described above, the relationship between the width L1 of the first suction area AR1, the width L2 of the second suction area AR2, and the distance L3 is L3>L1≧L2. Therefore, the air passage between the uppermost sheet and the lower sheet through which the separation air passes tends to taper from downstream to upstream in the sheet feeding direction D1. The separation air does not spread even in the area further upstream from the second suction area AR2, and the separation air is more likely to reach the rear end of the uppermost sheet. Furthermore, the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a are configured not to hinder the suction of the uppermost sheet. Note that the relationship between the width L1 of the first suction area AR1, the width L2 of the second suction area AR2, and the distance L3 is not limited to L3>L1≧L2, and the effect of suctioning the sheet by the second suction area AR2 can be obtained regardless of how it is set.

[0064] Furthermore, the control unit 1801 opens the second suction fan valve 1674 by turning on the second suction fan valve solenoid 1675 based on the conditions described later (step S4). This creates a negative pressure in the internal space of the second suction chamber 1672. Then, air is sucked through the holes 1676a of the chamber guide 1676, and the floating of the top sheet is assisted at the positions corresponding to the holes 1676a. This allows the separation air to flow from the leading edge to the trailing edge of the top sheet, i.e., from the downstream end to the upstream end in the sheet feeding direction D1, improving the separation of the top sheet and the lower sheets. The main purpose of the negative pressure of the second suction chamber 1672 is to assist the floating of the top sheet, and the top sheet does not necessarily have to be attracted to the chamber guide 1676. Note that step S4 may be omitted depending on the conditions described later. For example, when feeding a short sheet or a sheet with low adhesion, the second suction fan valve 1674 may be kept closed and the second suction fan 1671 may be kept stopped.

[0065] Then, the control unit 1801 turns off the side fan valve solenoid 1655 to close the side fan valve 1654 (step S5). The control unit 1801 also turns off the second suction fan valve solenoid 1675 to close the second suction fan valve 1674 (step S6). This is because once the separation air flows from the leading edge to the trailing edge of the top sheet, it is no longer necessary to float the sheet by the separation air or the negative pressure of the second suction chamber 1672. By stopping the separation air and releasing the negative pressure of the second suction chamber 1672, it is possible to reduce the transport resistance when feeding the top sheet and to suppress transport defects such as skew. The surface of the chamber guide 1676 is made of a material with low friction resistance and is configured to reduce the transport resistance between the top sheet and the chamber guide 1676.

[0066] Next, the control unit 1801 drives the belt driving roller 1612 to rotate the separation belt 1610 (step S7). At this time, the leading edge of the top sheet sucked by the separation belt 1610 is positioned above the leading edge guide 1131, so that the leading edge guide 1131 does not obstruct the feeding of the top sheet.

[0067] Next, the control unit 1801 judges whether the uppermost sheet has reached the drive roller 1710 of the drive roller unit 1700 (step S8). If it is judged that the uppermost sheet has reached the drive roller 1710 (step S8: Yes), the control unit 1801 turns off the front fan valve solenoid 1665 and the first suction fan valve solenoid 1605 (steps S9, S10). This closes the front fan valve 1664 and the first suction fan valve 1604, stops the separation air, and releases the suction of the uppermost sheet from the separation belt 1610.

[0068] The separation belt 1610 continues to rotate even after the first suction fan valve 1604 is closed, and when the rear end of the top sheet leaves the storage 110a, the control unit 1801 stops the belt drive roller 1612 (step S11). Even if the top sheet is attracted to the separation belt 1610 by the residual pressure in the first suction chamber 1602 after the first suction fan valve 1604 is closed, the separation belt 1610 continues to rotate, so that the conveyance resistance can be suppressed. Thereafter, the operations of steps S1 to S11 are repeated until the feeding of the number of sheets specified in the job is completed or the storage 110a is emptied of sheets.

[0069] [Setting the suction power of the second suction unit] Next, a flow for setting the suction power of the second suction unit 1670 will be described with reference to the flowchart shown in Fig. 8. The control unit 1801 can change the suction power and suction timing of the second suction unit 1670 based on sheet information 1820 input from the media operation unit 1800 or an external computer and the ambient humidity 1820d detected by the environment sensor 1623. Note that, although the following describes control for changing the suction power and suction timing of the second suction unit 1670, it is also possible to change only either the suction power or the suction timing.

[0070] An example of control for changing the suction power and suction timing of second suction unit 1670 will be described with reference to the flowchart in Fig. 8. As shown in Fig. 8, control unit 1801 determines whether sheet size 1820a is A3 size or larger (step S21). If it is determined that sheet size 1820a is smaller than A3 size (step S21: No), control unit 1801 proceeds to steps S31 to S33.

[0071] If it is determined that the sheet size 1820a is A3 or larger (step S21: Yes), the control unit 1801 determines whether the surrounding humidity 1820d is 60% or larger (step S22). If it is determined that the surrounding humidity 1820d is less than 60% (step S22: No), the control unit 1801 proceeds to steps S31 to S33.

[0072] If it is determined that the ambient humidity 1820d is 60% or more (step S22: Yes), the control unit 1801 determines that the sheet basis weight 1820b is 200 g / m 2 It is determined whether the sheet basis weight 1820b is 200 g / m or more (step S23). 2 If it is determined that the above is true (step S23: Yes), the control unit 1801 determines whether the sheet type 1820c is a coated sheet (step S24). If it is determined that the sheet type 1820c is a coated sheet (step S24: Yes), the control unit 1801 proceeds to steps S41 to S43. If it is determined that the sheet type 1820c is not a coated sheet (step S24: No), the control unit 1801 proceeds to steps S51 to S53.

[0073] In step S23, the sheet basis weight 1820b is 200 g / m 2 If it is determined that it is less than the predetermined value (step S23: No), the process proceeds to steps S61 to S63. In this embodiment, the suction force and suction timing of second suction unit 1670 are controlled in four different patterns.

[0074] Steps S31 to S33 are for cases where suction of the top sheet by the second suction unit 1670 is not necessary. In this case, the control unit 1801 sets the suction power of the second suction unit 1670 to 0, that is, sets the rotation speed of the second suction fan 1671 to 0 rpm (steps S31 and S32). Then, the control unit 1801 does not turn on / off the second suction fan valve solenoid 1675 (step S33). In this way, when the sheet size 1820a is smaller than A3 size or the ambient humidity 1820d is less than 60%, the second suction unit 1670 is not used. This is because, when the sheet is short, the second suction unit 1670 is not necessary to lift the trailing end of the top sheet, and when the ambient humidity 1820d is less than 60%, the sheets are not tightly attached to each other.

[0075] Steps S41 to S44 are for the case where suction of the topmost sheet by the second suction unit 1670 is most necessary. In this case, the control unit 1801 increases the suction power of the second suction unit 1670 (step S41). Specifically, the control unit 1801 sets the rotation speed of the second suction fan 1671 to 10,000 rpm (step S42). Then, the control unit 1801 makes the on-timing of the second suction fan valve solenoid 1675 earlier than normal and the off-timing later than normal (step S43). This makes it possible to increase the suction power of the second suction unit 1670 and lengthen the suction time.

[0076] Steps S51 to S54 are the next case where suction of the uppermost sheet by the second suction unit 1670 is required after steps S41 to S43. In this case, the control unit 1801 sets the suction power of the second suction unit 1670 to medium (step S51). Specifically, the control unit 1801 sets the rotation speed of the second suction fan 1671 to 6000 rpm (step S52). Then, the control unit 1801 sets the on / off timing of the second suction fan valve solenoid 1675 to normal (step S53).

[0077] Steps S61 to S64 are the case where suction of the uppermost sheet by the second suction unit 1670 is necessary next to the case of steps S51 to S53. In this case, the control unit 1801 reduces the suction power of the second suction unit 1670 (step S61). Specifically, the control unit 1801 sets the rotation speed of the second suction fan 1671 to 3000 rpm (step S62). Then, the control unit 1801 makes the on-timing of the second suction fan valve solenoid 1675 later than normal and makes the off-timing earlier than normal (step S63).

[0078] Thus, the larger the sheet size 1820a (particularly the length of the sheet), the higher the ambient humidity 1820d, the larger the sheet basis weight 1820b, and the more the sheet is coated, the more suction of the top sheet by the second suction unit 1670 is required.

[0079] As described above, in this embodiment, the second suction unit 1670 is provided upstream of the separation belt 1610 in the sheet feeding direction D1. This allows the second suction unit 1670 to assist in floating the trailing end of a long sheet such as B3 size or a sheet with a large basis weight, and allows separation air to escape from the leading edge to the trailing edge of the uppermost sheet. Therefore, regardless of the size, basis weight, type, and ambient humidity of the sheet, the sheets can be stably separated and conveyed, and poor sheet separation can be suppressed.

[0080] In addition, since the suction force of the second suction unit 1670 can be changed based on the sheet information 1820 and the ambient humidity 1820d, it is possible to suppress variation in the amount of floating of the top sheet that is sucked and floated by the second suction unit 1670. Therefore, it is possible to transport the sheets while separating them more stably regardless of the size, basis weight, type, ambient humidity, etc. of the sheets to be fed. More specifically, for a long and heavy sheet or a sheet type or ambient environment in which the sheets tend to adhere to each other, it is possible to more reliably separate the top sheet from the lower sheets by increasing the suction force of the second suction unit 1670. In addition, for a short and light sheet or a sheet type or ambient environment in which the sheets tend to adhere to each other less, it is possible to reduce the suction force of the second suction unit 1670 (including the case where suction is not performed) to reduce the sheet transport resistance and suppress transport defects such as skew.

[0081] <Second embodiment> Next, a second embodiment of the present invention will be described, in which the holes provided in the chamber guide 1676 of the first embodiment are configured to have an elongated hole shape. Therefore, the same configuration as the first embodiment will be described by omitting illustrations or by assigning the same reference numerals in the drawings.

[0082] Fig. 9(a) is a bottom view showing a feeding unit 260a according to the second embodiment, and Fig. 9(b) is an enlarged view showing a plurality of long holes 2676a provided in a chamber guide 2676. As shown in Fig. 9(a), the feeding unit 260a according to this embodiment has a separation belt 1610, a first suction unit 1600, and a second suction unit 2670. Although not shown in Fig. 9(a), the feeding unit 260a has a separation air unit 170, a separation air unit 180, and a drive roller unit 1700, similar to the first embodiment.

[0083] The second suction unit 2670 as an upstream suction section has a second suction fan 1671 (see FIG. 3(a)), a second suction chamber 2672, and a second suction fan valve 1674 (see FIG. 3(a)). The second suction chamber 2672 is connected to the second suction fan 1671, and has a space therein.

[0084] A chamber guide 2676 is attached to the second suction chamber 2672 so as to cover the opening 2672a of the second suction chamber 2672, and a plurality of long holes 2676a are provided in the chamber guide 2676 as a guide member. Each long hole 2676a is longer in the sheet feeding direction D1 than in the width direction W. The plurality of long holes 2676a of the chamber guide 2676 communicate with the opening 2672a of the second suction chamber 2672. Therefore, when the internal space of the second suction chamber 2672 becomes negative pressure, the air around the chamber guide 2676 can be sucked toward the inside of the second suction chamber 2672 through the opening 2672a and the plurality of long holes 2676a of the chamber guide 2676. When a sheet is present near the lower surface of the chamber guide 2676, the sheet floats toward the chamber guide 2676. In this embodiment as well, the relationship between the width L1 of the first suction region AR1, the width L2 of the second suction region AR2, and the distance L3 satisfies L3>L1≧L2.

[0085] The feeding preparation operation and feeding operation by the feeding unit 260a of this embodiment are similar to those of the first embodiment described in FIG. 7. Here, immediately after the second suction fan valve 1674 is closed in step S6 of FIG. 7, the negative pressure in the second suction chamber 2672 remains, and the sheet may be transported while still being attracted to the chamber guide 2676. As described above, the separation belt 1610 generates a conveying force for the sheet by biting the sheet with the edge portions 1610b (see FIG. 3(b)) of the multiple circular holes 1610a. However, if the sheet is transported while still being attracted to the chamber guide 2676, as shown in FIGS. 9(a) and 9(b), the sheet slides on the edge portions 2676b of the long holes 2676a provided in the chamber guide 2676, and the sheet conveying resistance increases. The edge portion 2676b is an edge of the downstream end portion of the slot 2676a in the sheet feeding direction D1, and extends so as to intersect with the sheet feeding direction D1.

[0086] In this embodiment, the chamber guide 2676 is provided with a long hole extending in the sheet feeding direction D1, so that the conveying resistance can be reduced compared to the first embodiment in which multiple circular holes 1676a are provided. This is because the edge portions 2676b of the multiple long holes 2676a are smaller than the edge portions of the circular holes 1676a in the first embodiment.

[0087] Furthermore, since the edge portions 2676b of the multiple long holes 2676a are located at the same position in the sheet feeding direction D1, the transport resistance acting on the sheet due to the edge portions 2676b tends to be uniform in the width direction W. This makes it possible to reduce transport defects such as skewing of the sheet. The surface of the chamber guide 2676 is made of a material with low friction resistance and is configured to reduce the transport resistance between the uppermost sheet.

[0088] <Third embodiment> Next, a third embodiment of the present invention will be described, in which a plurality of driven rollers 1680 are provided on the chamber guide 2676 of the second embodiment. Therefore, the same configuration as the second embodiment will be described with the same reference numerals or will be omitted from the illustration.

[0089] 10 is a perspective view showing a second suction unit 3670 as an upstream suction section according to the third embodiment. As shown in FIG. 10, the second suction unit 3670 has a plurality of driven rollers 1680 as a rotating body that rotates in contact with a sheet fed in a sheet feeding direction D1. The plurality of driven rollers 1680 are provided in the second suction region AR2, and are arranged such that a part of the outer shape of each roller protrudes from a plurality of long holes 2676a of the chamber guide 2676.

[0090] Therefore, when the sheet is sucked into the chamber guide 2676, the sheet is pressed against the driven roller 1680. Even if there is residual pressure in the second suction chamber 2672, when the sheet is transported in the sheet feeding direction D1, the driven roller 1680 rotates in response to the transported sheet, so that the transport resistance is reduced.

[0091] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described, in which a plurality of ribs 1690 are provided on the chamber guide 2676 of the second embodiment. Therefore, the same configuration as the second embodiment will be described with the same reference numerals or will be omitted from the illustration.

[0092] Fig. 11 is a perspective view showing a second suction unit 4670 as an upstream suction section according to the fourth embodiment. As shown in Fig. 11, the second suction unit 4670 has a plurality of ribs 1690 that extend in the sheet feeding direction D1 and are slidable on the conveyed sheet. The width of the ribs 1690 in the width direction W is shorter than the length of the ribs 1690 in the sheet feeding direction D1. The plurality of ribs 1690 are provided in the second suction region AR2 and are alternately provided in the width direction W with the plurality of long holes 2676a of the chamber guide 3676 as a guide member.

[0093] Therefore, when the sheet is sucked into the chamber guide 3676, the sheet is pressed against the tips of the multiple ribs 1690. Even if there is residual pressure in the second suction chamber 3672, the sheet transported in the sheet feeding direction D1 slides against the multiple ribs 1690, so that the transport resistance is reduced.

[0094] <Other embodiments> In any of the above-described embodiments, the second suction unit 1670, 2670, 3670, 4670 having one second suction chamber 1672, 2672 is arranged as an auxiliary means for flowing the separation air to the rear end of the sheet, but the present invention is not limited to this. For example, if a suction unit is further added in addition to the second suction unit 1670, 2670, 3670, 4670 to assist the floating of the sheet with a plurality of suction units, it becomes possible to handle sheets of a larger size. In addition, the second suction unit 1670, 2670, 3670, 4670 may be configured to be movable in the sheet feeding direction D1, and the second suction unit 1670, 2670, 3670, 4670 may be moved in the sheet feeding direction D1 depending on the attributes of the sheet to be fed and the humidity environment.

[0095] In addition, in each of the above-described embodiments, the separating air unit 170 and the separating air unit 180 are separately configured, and the uppermost sheet and the lower sheet are separated by the separating air and the separating air, but this is not limited to this. For example, the separating air unit 170 may be omitted, and the uppermost sheet and the lower sheet may be separated by the separating air unit 180 and the separating belt 1610.

[0096] In addition, in any of the above-described embodiments, the side fan valve 1654 and the second suction fan valve 1674 are closed (steps S5 and S6) before driving the separation belt 1610, but this is not limited to the above. For example, instead of closing the side fan valve 1654 and the second suction fan valve 1674, the rotation speed of the side fan 1651 and the second suction fan 1671 may be reduced or the side fan 1651 and the second suction fan 1671 may be stopped. Furthermore, when driving the separation belt 1610, the side fan valve 1654 and the second suction fan valve 1674 may be left open.

[0097] In addition, in any of the above-described embodiments, the sheet detection flag 1620a and the sheet presence / absence detection flag 1621a form an air passage through which the separation air passes, but the present invention is not limited to this. For example, a pressing part for pressing down the top sheet from above may be provided in addition to each sensor flag.

[0098] In addition, in any of the above-described embodiments, the suction power and suction timing of the second suction units 1670, 2670, 3670, and 4670 are controlled in four patterns based on the sheet information 1820 and the ambient humidity 1820d, but this is not limiting. For example, the suction power and suction timing of the second suction units 1670, 2670, 3670, and 4670 may be constant regardless of the sheet information 1820 and the ambient humidity 1820d. Furthermore, the suction power and suction timing of the second suction units 1670, 2670, 3670, and 4670 may be controlled in two to three patterns or five or more patterns.

[0099] In addition, in any of the above-described embodiments, the suction power of the second suction units 1670, 2670, 3670, 4670 is changed based on the size (length in the sheet feeding direction D1), basis weight, type, and ambient humidity of the sheet supported by the lifter plate 1140, but is not limited thereto. For example, the suction power of the second suction units 1670, 2670, 3670, 4670 may be changed based on any one or any combination of the size (length in the sheet feeding direction D1), basis weight, type, and ambient humidity of the sheet. That is, the suction power of the second suction units 1670, 2670, 3670, 4670 may be changed based on at least one of the size (length in the sheet feeding direction D1), basis weight, type, and ambient humidity of the sheet.

[0100] In addition, in each of the above-described embodiments, the feeding module 100 and the print module 200 are configured separately, but the present invention may be applied to an image forming apparatus in which these are integrally formed. Note that the image forming apparatus includes a printer, a copier, a facsimile, and a multifunction machine, and refers to an apparatus that forms an image on a sheet used as a recording medium based on image information input from an external PC or image information read from a document. In addition, an image forming apparatus may be connected to an accessory device such as an optional feeder, an image reader, and a sheet processing device in addition to a main body having an image forming function, and the entire system to which such accessory devices are connected is also a type of image forming apparatus.

[0101] In addition, in any of the above-described embodiments, the feeding module 100 has been used as an example of the sheet feeding device, but the present invention is not limited thereto. For example, the feeding module 100 and the print module 200 may be the sheet feeding device, or the entire inkjet recording system 1 may be the sheet feeding device. In addition, any module including the feeding module 100 in the inkjet recording system 1 may be combined to form the sheet feeding device. In this case, the control unit 1801 that controls the suction force of the second suction units 1670, 2670, 3670, and 4670 of the sheet feeding device may be disposed anywhere in the sheet feeding device. For example, when the entire inkjet recording system 1 is the sheet feeding device, the control unit 1801 disposed in the print module 200 may control the suction force of the second suction units 1670, 2670, 3670, and 4670.

[0102] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0103] 170: first blowing section (separating air unit) / 180: second blowing section (separating air unit) / 800: air blowing section / 100: sheet feeding device (feeding module) / 1140: sheet support section (lifter plate) / 1610: feeding belt (separating belt) / 1610a: multiple holes / 1620: first detection section (sheet detection sensor) / 1620a: first pressing section (sheet detection flag) / 1621: second detection section (sheet presence / absence detection sensor) / 1621a: second pressing section (sheet presence / absence detection flag) / 1670, 2670, 3670, 4670: upstream suction section (second suction unit) / 1671: fan (second suction fan) / 1676, 2676, 3676: guide member (chamber guide) / 1676a: multiple holes / 1680: rotor (driven roller) / 1690: rib / 1801: control section / 2676a: long hole / AR1: first suction area / AR2: second suction area / D1: sheet feeding direction / L1, L2: width / L3: distance / W: width direction

Claims

1. A seat support section that supports the seat, An air blowing unit that blows air from the downstream end to the upstream end in the sheet feeding direction of the sheet supported by the sheet support unit, A feeding belt that feeds the top sheet of the sheets to which air has been blown by the aforementioned air blowing unit while simultaneously sucking it up, It comprises an upstream suction unit positioned upstream of the feeding belt in the sheet feeding direction and for sucking up the uppermost sheet, The feeding belt has a first suction region that faces the uppermost sheet and sucks the uppermost sheet, The upstream suction section has a second suction region that faces the uppermost sheet and sucks the uppermost sheet, In the width direction perpendicular to the sheet feeding direction, the width of the second suction region is narrower than the width of the first suction region. A sheet feeding device characterized by the following features.

2. The feeding belt has a plurality of holes that suck the uppermost sheet by negative pressure, The upstream suction section has a guide member having a plurality of holes that suck the uppermost sheet by negative pressure, The first suction region is the region of the feed belt in which the plurality of holes are provided. The second suction region is the region of the guide member in which the plurality of holes are provided. The sheet feeding device according to feature 1.

3. Each of the plurality of holes provided in the second suction region is an elongated hole that is longer in the sheet feeding direction with respect to the width direction. The sheet feeding device according to feature 2.

4. The upstream suction section is provided in the second suction region and has a rotating body that contacts and is driven to rotate by the sheet being fed in the sheet feeding direction. The sheet feeding device according to feature 2.

5. The guide member has ribs provided in the second suction region, The rib extends in the sheet feeding direction and slides against the sheet being fed in the sheet feeding direction. The sheet feeding device according to feature 2.

6. In the width direction, a first pressing portion is positioned on one side with respect to the center of the sheet supported by the sheet support portion and presses down on the uppermost sheet from above, The device further comprises a second pressing portion, which is positioned on the other side of the center in the width direction and presses down on the uppermost sheet from above. A sheet feeding device according to any one of claims 2 to 5.

7. The first pressing portion and the second pressing portion are arranged between the feeding belt and the guide member in the sheet feeding direction, The sheet feeding device according to feature 6.

8. The feeding belt and the guide member are arranged between the first pressing portion and the second pressing portion in the width direction. The sheet feeding device according to feature 6.

9. In the width direction, a first pressing portion is positioned on one side with respect to the center of the sheet supported by the sheet support portion and presses down on the uppermost sheet from above, The device further comprises a second pressing portion, which is positioned on the other side of the center in the width direction and presses down on the uppermost sheet from above. The sheet feeding device according to feature 1.

10. A first detection unit detects the height of the uppermost sheet supported by the sheet support unit based on the position of the first pressing unit, The device further includes a second detection unit that detects whether or not a sheet is supported by the sheet support unit based on the position of the second pressing unit, The sheet feeding device according to feature 9.

11. In the width direction, the width of the second suction region is less than or equal to the distance between the first pressing portion and the second pressing portion. The sheet feeding device according to feature 9.

12. The aforementioned upstream suction section has a fan, The system further includes a control unit capable of changing the suction force of the upstream suction unit by changing the rotation speed of the fan. The sheet feeding device according to feature 11.

13. The control unit can change the timing of suction of the uppermost sheet by the upstream suction unit. The sheet feeding device according to feature 12.

14. The control unit changes the suction force of the upstream suction unit based on information regarding the length, basis weight, and type of the sheet supported by the sheet support unit in the sheet feeding direction, and the humidity around the sheet support unit. The sheet feeding device according to feature 12.

Images