Paper feeder

Abstract

To provide a sheet feeding device which can continue a sheet feeding operation without stopping the device by conveying a defective sheet to a discharge part with a vacancy when any of the plurality of discharge parts discharging the defective sheet is in the full state.SOLUTION: A sheet feeding device comprises: first and second escape parts ES1, ES2 which are provided on an upstream side and a downstream side of a conveyance path of a sheet and discharge defective sheets P1, P2 generated in the conveyance path, respectively; upstream side full detection means which detects a full state with the defective sheets P2 in the second escape part ES2; and control means which conveys the defective sheet P2 to the second escape part ES2, and upon detection by the upstream side full detection means, of the full state in the second escape part ES2, discharges the defective sheet P2 to the first escape part ES1.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device that discharges defective sheets generated in a transport path to a predetermined discharge section. [Background technology]

[0002] Conventionally, image forming apparatuses such as printers and copiers are sometimes connected to a paper feeder equipped with multiple paper feed units for continuously feeding a large amount of sheets, or sometimes multiple individual paper feeders are connected together. In this way, by providing multiple paper feed units or paper feeders, it is possible to continuously form images on more sheets without stopping the image forming apparatus. In addition, since it is possible to store a variety of sheets with different sizes and paper qualities, it has the advantage of eliminating the trouble of replacing sheets.

[0003] Patent Document 1 discloses an image forming apparatus having a configuration including a plurality of feeding units that feed sheets to the image forming units. The feeding units each include an escape section for discharging sheets that have been fed in multiple increments without being transported to the image forming apparatus, so that the feeding operation of normally fed sheets can be continued without stopping the entire apparatus. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-279168 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, an escape section is provided in the paper feed path between the downstream paper feed unit among the multiple connected paper feed units and the image forming apparatus, and defective sheets due to double feeding or the like in the multiple paper feed units are discharged to this escape section. Even in a paper feed unit equipped with such an escape section, when the escape section becomes full of sheets, the apparatus must be stopped in order to temporarily discharge the sheets in the full escape section. In addition, if there are sheets that cannot be discharged to the escape section and are stopped in the paper feed path, the sheets must be removed before the apparatus can be restarted. Thus, there are problems in that the more frequently the escape section becomes full, the lower the productivity becomes, and the more frequent the work of removing defective sheets becomes.

[0006] Therefore, the present invention aims to provide a paper feeding device having multiple discharge sections for discharging defective sheets, which detects whether the multiple discharge sections are full of sheets being discharged, and when any of the discharge sections is full, transports the defective sheet to an available discharge section, thereby allowing the paper feeding operation to continue without stopping the device. [Means for solving the problem]

[0007] In order to solve the above problems, the paper feeding device of the present invention comprises an upstream paper feeding unit having a transport path that guides sheets in a predetermined transport direction, a downstream paper feeding unit provided downstream of the upstream paper feeding unit in the transport direction and having a transport path that guides sheets transported from the upstream paper feeding unit, an upstream discharge section provided in the upstream paper feeding unit and discharging defective sheets generated on the transport path, a downstream discharge section provided in the downstream paper feeding unit and discharging defective sheets generated on the transport path, and an upstream full detection means for detecting a full state of the defective sheets discharged to the upstream discharge section, The upstream paper feeding unit discharges the defective sheets in the upstream paper feeding unit to the upstream discharge section, and has an upstream control means that transports the defective sheets to the downstream paper feeding unit when the upstream full detection means detects that the upstream discharge section is full, and the downstream paper feeding unit has a downstream control means that discharges the defective sheets transported to the downstream paper feeding unit by the upstream control means to the downstream discharge section. In order to solve the above problem, the sheet feeding system of the present invention includes a first feeding device having a first storage section in which sheets are stored, a first feeding means for feeding the sheets stored in the first storage section, and a first transport path for guiding the sheets fed by the first feeding means, and a second feeding device having a second storage section in which sheets are stored, a second feeding means for feeding the sheets stored in the second storage section, and a second transport path for guiding the sheets fed by the second feeding means, the second feeding device having a second transport path along which the sheets fed from the first feeding device are transported. the sheet conveying device includes a sheet conveying unit, a first discharge section provided in the first feeding device and discharging a sheet for which a transport failure has occurred on the first transport path, a second discharge section provided in the second feeding device and discharging a sheet for which a transport failure has occurred on the second transport path, a detection means for detecting that the amount of sheets discharged to the first discharge section is equal to or greater than a predetermined amount, and a control means for controlling the sheet for which a transport failure has occurred on the first transport path to be discharged to the second discharge section when the detection means detects that the amount of sheets discharged to the first discharge section is equal to or greater than the predetermined amount. Effect of the Invention

[0008] According to the paper feeder of the present invention, when the upstream fullness detection means detects that the upstream discharge section is full of defective sheets, the defective sheets are guided to the downstream discharge section and discharged, so that even if many defective sheets occur, the paper feeder can continue to feed paper without stopping, thereby improving productivity. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an overall configuration of an image forming system including a paper feeder according to the present invention; [Diagram 2] FIG. 2 is a block diagram showing a control configuration of the image forming system. [Diagram 3] FIG. 2 is a cross-sectional view showing a main configuration of the paper feed device. [Figure 4] FIG. 2 is a cross-sectional view showing the arrangement of various sensors in the paper feeder; [Diagram 5] 4 is a cross-sectional view showing the configuration of a main part, focusing on an escape portion. FIG. [Figure 6] 11A and 11B are explanatory diagrams showing the conveying and discharging operation of a defective sheet. [Figure 7] 13 is a flowchart of a process performed by a control unit when multiple sheets are fed. [Figure 8] 13 is a flowchart of a process in a fullness detection unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the overall configuration of an image forming system 100 including an image forming apparatus 101 and a paper feeder DK of the present invention that can be connected to the image forming apparatus 101. In this embodiment, the paper feeder DK has a two-stage configuration of a downstream paper feed unit (first paper feed unit) DK1 and an upstream paper feed unit (second paper feed unit) DK2, but the number of stages of paper feed units is not limited and may be a configuration in which multiple independent paper feed units are connected. In the following description, a laser printer system using an electrophotographic method will be described as an example of the image forming apparatus 101. Note that the image forming apparatus 101 may be a copier, facsimile, multifunction machine, etc. other than a printer, and may be of another type such as an inkjet type, not limited to an electrophotographic type.

[0011] The first paper feed unit DK1 and the second paper feed unit DK2 each have a plurality of storage sections (storage units) capable of storing a plurality of sheets, and can feed sheets from each storage unit toward the image forming apparatus 101. Note that types of sheets that can be used include plain paper, thin paper, thick paper, and plastic sheets.

[0012] 2 is a block diagram showing the control configuration and mutual connection relationship of the image forming apparatus 101 and the sheet feeding apparatus DK in the image forming system 100. The image forming apparatus 101 includes a control means (control unit) CON0 for controlling the conveyance of sheets and the execution of image forming processing, an operation unit 102, and a notification means (display unit) 103. The first sheet feeding unit DK1 and the second sheet feeding unit DK2 constituting the sheet feeding apparatus DK include control units (CON1, CON2) for controlling the conveyance and feeding of sheets, sheet sensors S1 to S13 for detecting sheets passing through each conveyance path, defective sheet detection means (multiple feed sensors) DFS1 to DFS3 for detecting defective sheets due to multiple feeds or the like, conveyance motors M1 to M14, lift motors M15 to M17, a solenoid SOL, and the like. In the sheet feeding apparatus DK, the control unit CON1 of the first sheet feeding unit DK1 and the control unit CON2 of the second sheet feeding unit DK2 are electrically connected to each other. Further, the sheet feeding device DK and the image forming device 101 are electrically connected to each other via a control unit CON1 of the first sheet feeding unit DK1 and a control unit CON0 of the image forming device 101.

[0013] 1, the image forming apparatus 101 conveys various sheets fed from a paper feed section 20 (plurality of paper feed cassettes 21) and a plurality of storage containers in a paper feed device DK (first paper feed unit DK1, second paper feed unit DK2) in a separated state one by one to an image forming section 10. Then, after an image is formed on the sheet in the image forming section 10, the sheet is discharged from a discharge tray 29.

[0014] The first sheet feeding unit DK1 is provided with a through-path portion TP that relays and conveys the sheets fed from the second sheet feeding unit DK2 to the image forming apparatus 101.

[0015] The operation unit 102 is used to select the sheets to be fed to the image forming unit 10 from the sheet feeding unit 20, the first sheet feeding unit DK1, or the second sheet feeding unit DK2, and to specify the printing method, the number of copies to be printed, etc. The display unit 103 also displays which storage unit of the sheet feeding unit 20, the first sheet feeding unit DK1, or the second sheet feeding unit DK2 the sheets are being fed from, and whether or not there is any double feeding of sheets. It is also possible to remotely operate the operation unit 102 from an information terminal such as an external PC or smartphone without directly operating the operation unit 102.

[0016] The image reading device 2 provided in the image forming apparatus 101 irradiates light from a scanning optical system light source onto a document placed on a platen 3, and inputs the reflected light into a CCD to read the document image. An automatic document feeder (ADF) 4 can be connected to the image reading device 2, and a document set on a tray 5 can be automatically transported to a reading section of the image reading device 2 to read the document image. The read document image is then converted into an electrical signal and transmitted to a laser scanner 13 of the image forming section 10, which will be described later. Note that the laser scanner 13 may also receive image data sent from an external terminal device or the like.

[0017] The paper feed section 20 includes a plurality of paper feed cassettes 21 for storing various types of sheets, a pickup roller 22, and a pair of separation and conveyance rollers 25. The sheets stored in the paper feed cassette 21 are separated one by one by the pickup roller 22 and the pair of separation and conveyance rollers 25, which move up and down and rotate at a predetermined timing.

[0018] The sheet transport path 34 includes a transport roller pair 31 and a registration roller pair 33, and the sheet guided from the transport roller pair 31 by the registration roller pair 33 is sent to the image forming section 10 at a predetermined timing. The sheet fed from the sheet feeding device DK joins the sheet transport path 34 via a transport roller pair 39 and a connection path TR6 provided in the first sheet feeding unit DK1, and is transported into the image forming apparatus 101.

[0019] The image forming unit 10 includes a photosensitive drum 11, a charger 12, a laser scanner 13, a developing unit 14, a transfer unit 15, a cleaner 17, etc. During image formation, the photosensitive drum 11 is rotated, and first, the surface of the photosensitive drum 11 is uniformly charged by the charger 12. Then, the charged photosensitive drum 11 is irradiated with laser light from the laser scanner 13, which is emitted in response to an image signal, to form an electrostatic latent image on the photosensitive drum 11. Furthermore, the electrostatic latent image thus formed on the photosensitive drum 11 is visualized as a toner image by the developing unit 14.

[0020] Thereafter, the toner image on the photosensitive drum 11 is transferred onto a sheet by a transfer unit 15. Furthermore, the sheet onto which the toner image has been transferred is transported to a fixing unit 16 where the toner image is fixed, and then the sheet is discharged onto a discharge tray 29 via a pair of discharge rollers 19.

[0021] When a toner image is formed on the back surface of the sheet, the sheet discharged from the fixing device 16 is transported to a switchback path 18. Then, in a state where the sheet is turned over by the switchback path 18, the sheet is transported again to the transfer device 15 of the image forming unit 10. The sheet with the toner image transferred to the back surface is transported to the fixing device 16, where the toner image is fixed, and then the sheet is discharged to a discharge tray 29 by a pair of discharge rollers 19. Note that any residual toner remaining on the photosensitive drum 11 after the transfer is removed by a cleaner 17.

[0022] The control unit CON0 has a CPU, a ROM, and a RAM. The CPU controls each part while reading a program corresponding to a control procedure stored in the ROM. In addition, working data and input data are stored in the RAM, and the CPU performs control by referring to the data stored in the RAM based on the above-mentioned programs, etc.

[0023] In the operation unit 102 provided in the image forming apparatus 101, image forming conditions, such as sheet size, color / monochrome printing, number of copies to be printed, single-sided / double-sided printing, enlarged / reduced printing, and other printing conditions are set.

[0024] Next, the sheet feeding device DK will be described in detail with reference to Figures 3 to 5. Since the first sheet feeding unit DK1 and the second sheet feeding unit DK2 have the same configuration except for the through path section TP, the description will be based on the first sheet feeding unit DK1.

[0025] The first paper feed unit DK1 includes a plurality of storage cabinets LO1-LO3, a plurality of transport paths TR1-TR5 extending from the storage cabinets LO1-LO3, a plurality of transport roller pairs arranged on each transport path, sheet sensors S1-S13, double feed sensors DFS1-DFS3, motors M1-M17, a through path part TP, etc. In this embodiment, the three storage cabinets LO1-LO3 are arranged in three tiers in the vertical direction, and the through path part TP is provided between the lower storage cabinet LO3 and the middle storage cabinet LO2. The second paper feed unit DK2 does not include the through path part TP and the double feed sensor DFS3.

[0026] A sheet fed from the upper storage LO1 is transported to the transport path TR1, a sheet fed from the middle storage LO2 is transported to the transport path TR2, and a sheet fed from the lower storage LO3 is transported to the transport path TR3. A sheet transported from the second paper feed unit DK2 via the through path section TP is transported to the transport path TR4. The transport path TR2 merges with the transport path TR1 midway. The transport paths TR1, TR3, and TR4 merge at a junction J1, and the sheet is transported to the transport roller pair 39 via the transport path TR5 and is sent to the image forming device 101 via the connection path TR6.

[0027] As shown in Fig. 4, the conveying path TR1 after merging with the conveying path TR2, the through path section TP, and the conveying path TR3 are provided with double feed sensors DFS1 to DFS3 for detecting double feed of sheets, respectively. A defective sheet for which a double feed has been detected by the double feed sensors DFS1 to DFS3 is conveyed to the conveying path TR5. A downstream discharge section (first escape section) ES1 for discharging a defective sheet for which a double feed has been detected is provided below the conveying path TR5. The defective sheet is discharged to the first escape section ES1 by switching the conveying path by a switching member (flapper) FL1 provided on the conveying path TR5. Details of the process when a double feed is detected will be described later.

[0028] Sheets fed from storage units LO1 to LO3 are transported to a connection path TR6 via transport paths TR1, TR3, and TR4. Each part of the first paper feed unit DK1 is controlled by a control unit CON1. ​​The control unit CON1 has a CPU, a ROM, and a RAM. The control unit CON1 is capable of communicating with a control unit CON0 of the image forming apparatus 101, and controls the timing of sheet feeding and the like by communicating with the control unit CON0.

[0029] 3, storage LO1 has a sheet feeding section 40a that feeds sheets toward image forming apparatus 101, and a stacking tray 44a on which a plurality of sheets are stacked. The stacking tray 44a can be raised and lowered in the vertical direction by a lifting mechanism 45a driven by a lifting motor M15. The stacking tray 44a is lowered to a predetermined position when sheets are stacked, and gradually rises when the stacked sheets are fed.

[0030] The sheet feeding section 40a has a pickup roller 43a as a sheet conveying means, a separation conveying roller pair 41a consisting of a conveying roller and a retard roller, a conveying roller pair 42a, etc. The pickup roller 43a and the separation conveying roller pair 41a are rotated by a conveying motor M1, and the conveying roller pair 42a is rotated by a conveying motor M2. The sheet feeding section 40a also has a sheet sensor S1 that detects the presence or absence of a sheet on the downstream side of the separation conveying roller pair 41a in the conveying direction, and a sheet sensor S2 that detects the presence or absence of a sheet on the upstream side of the conveying roller pair 42a in the conveying direction.

[0031] The pickup roller 43a is provided above the stacking tray 44a and contacts the top sheet of the sheets stacked on the raised stacking tray 44a to feed it. For this purpose, the pickup roller 43a is disposed near the leading edge of the sheet in the sheet conveying direction so as to be able to press the top sheet on the stacking tray 44a with an appropriate force. Then, the pickup roller 43a rotates to feed out the top sheet.

[0032] When two or more overlapping sheets are fed from the pickup roller 43a, that is, when two or more overlapping sheets are fed, the pair of separation and conveyance rollers 41a separates the sheets and conveys only one sheet.

[0033] The sheet separated and conveyed by the separation conveying roller pair 41a is conveyed to a conveying path TR1 by a conveying roller pair 42a. A plurality of conveying roller pairs rotated by conveying motors M7 and M8 are arranged on the conveying path TR1. As shown in FIG. 4, a sheet sensor S7 for detecting the presence or absence of a sheet on the downstream side in the conveying direction and a sheet sensor S8 for detecting the presence or absence of a sheet on the upstream side in the conveying direction are arranged on the conveying path TR1.

[0034] Storage cabinets LO2 and LO3 include sheet feeding units 40b and 40c that feed sheets toward image forming apparatus 101, stacking trays 44b and 44c on which a plurality of sheets are stacked, and lifting mechanisms 45b and 45c. Note that the configurations of sheet feeding units 40b and 40c and conveying motors M3 to M6 are similar to those of sheet feeding unit 40a, and the configurations of lifting mechanisms 45b and 45c and lifting motors M16 and M17 are similar to those of lifting mechanism 45a, and therefore descriptions thereof will be omitted.

[0035] In the through-path section TP, the sheet is transported through the device by a conveyor 50 driven by a transport motor M14. In addition, in the through-path section TP, a double-feed sensor DFS3 is disposed upstream of the conveyor 50 in the transport direction to detect whether or not two or more sheets are being fed in the through-path section TP.

[0036] The sheet conveyed by the conveyor 50 is conveyed into a conveying path TR4 by a conveying roller pair 51 rotated and driven by a conveying motor M12 and a conveying roller pair 52 rotated and driven by a conveying motor M13.

[0037] A sheet sensor S12 that detects the presence or absence of a sheet on the upstream side of the conveying roller pair 51 in the conveying direction, and a sheet sensor S13 that detects the presence or absence of a sheet on the upstream side of the conveying roller pair 52 in the conveying direction are arranged on the conveying path TR4.

[0038] The transport paths TR1, TR3, and TR4 join at a junction J1 and are connected to a transport path TR5. A pair of transport rollers 53 rotated by a transport motor M10 and a pair of transport rollers 54 rotated by a transport motor M11 are arranged on the transport path TR5, and a sheet sent out by the pair of transport rollers 54 is transported to the image forming apparatus 101 via a connection path TR6.

[0039] Also, a sheet sensor S10 that detects the presence or absence of a sheet on the downstream side of the pair of conveying rollers 53 in the conveying direction, and a sheet sensor S11 that detects the presence or absence of a sheet on the upstream side of the pair of conveying rollers 54 in the conveying direction are arranged on the conveying path TR5. Also, a flapper FL1 is arranged on the conveying path TR5. This flapper FL1 is driven by a solenoid SOL, and directs a defective sheet conveyed to the conveying path TR5 from the middle of the path toward the connection path TR6 toward the discharge tray 60 of the first escape section ES1.

[0040] The first escape section ES1 is provided below the transport paths TR3 and TR5 for transporting sheets from the storage LO3 to the image forming device 101, below the connection path TR6, and below the junction J1 of the transport paths TR1, TR2, and TR3. As shown in FIG. 3, the first escape section ES1 has a discharge area for the overlapped sheets in the transport direction of the sheets transported on the transport paths TR3 and TR5, which is a wide range from a position adjacent to the image forming device 101 to a position adjacent to the storage LO3. In other words, the length of the first escape section ES1 in the transport direction of the sheets passing through the transport paths TR3 and TR5 is the length from the transport path TR3 to the connection path TR6 via the junction J1 and the flapper FL1. In addition, the first escape section ES1 has a discharge area for the overlapped sheets in the height direction from the position of the transport path TR3, that is, from the position of the flapper FL1 to a position lower than the bottom surface 61 of the first paper feed unit DK1.

[0041] In this way, the first paper feeding unit DK1 can discharge a large number of sheets to the first escape section ES1 by forming a large discharge area within the device for discharging sheets that have been fed multiple times at the first escape section ES1.

[0042] The second sheet feeding unit DK2 has the same configuration as the first sheet feeding unit DK1, except that the through path section TP, the transport motors M12 to M14, and the double feed sensor DFS3 are removed.

[0043] Next, the operation of transporting and discharging defective sheets remaining on the transport path of the second paper feed unit DK2 due to double feeding or prior feeding in the paper feed device DK will be described with reference to the flowcharts in Figures 6 and 7. Note that the second paper feed unit DK2 has the same configuration as the first paper feed unit DK1 except for the through path section TP, so details of the paper feed operation from each storage will be omitted. Also, common parts are indicated by the same reference numerals as the first paper feed unit DK1.

[0044] As shown in FIG. 6, in the second sheet feeding unit DK2, when the double feed of sheets is detected by either of the double feed sensors DFS1 and DFS2, the detected defective sheet P2 is guided to the flapper FL2 and discharged to the upstream discharge section (second escape section) ES2. In the present invention, an upstream full-fill detection means is provided for detecting that the defective sheet P2 discharged to the second escape section ES2 is full. When the upstream full-fill detection means detects that the second escape section ES2 is full, the control is performed so that the defective sheet P2 that has been double-fed thereafter is conveyed toward the first escape section ES1 of the first sheet feeding unit DK1. Note that the defective sheet P1 that occurs in the first sheet feeding unit DK1 is guided to the flapper FL1 and discharged to the first escape section ES1. The first sheet feeding unit DK1 also has a downstream full-fill detection means for detecting that the first escape section ES1 is full.

[0045] Fig. 7 shows the processing procedure in the control section (CON1, CON2) when a double feed or the like occurs. In this process, first, it is detected whether the second escape section SE2 is full or not (ST01). If it is not full, the defective sheet P2 generated in the second paper feed unit DK2 is discharged directly to the second escape section ES2 (ST02) (Fig. 6(a)).

[0046] After that, if there is still a remaining defective sheet P2, the process returns to step (ST01) again to detect whether the second escape section SE2 is full or not. At this time, if the second escape section SE2 is not full due to the previous discharge of the defective sheet P2 to the second escape section SE2, the sheet continues to be discharged to the second escape section SE2.

[0047] On the other hand, if the second escape section SE2 is full, it is detected whether the first escape section ES1 of the first sheet feeding unit DK1 is full (ST03). If it cannot be detected that the first escape section ES1 is full, the defective sheet P2 generated in the second sheet feeding unit DK2 is conveyed to the first sheet feeding unit DK1 via the through path section TP, guided by the flapper FL1, and discharged to the first escape section ES1 (ST04) (FIG. 6(b)).

[0048] If there are any remaining sheets, the process returns to step (ST01) again to detect whether the second escape section SE2 is full. At this time, since the second escape section SE2 is already full when the previous defective sheet P2 is conveyed and discharged, the subsequent defective sheet P2 will also be discharged to the first escape section ES1.

[0049] If the first escape section ES1 is full in step (ST03), the sheet transport operation is stopped (FIG. 6(c)), and the image forming apparatus 101 is notified that the first escape section ES1 and the second escape section ES2 are full (ST07, ST08). In response to this, the image forming apparatus 101 displays a full error on the display unit 103. Then, when there are no more defective sheets, that is, when all defective sheets in the transport path of the sheet feeding device DK have been transported to and discharged through the first escape section ES1 and the second escape section ES2, the transport and discharge operations in the sheet feeding device DK are stopped (ST06).

[0050] Next, an example of a fullness detection unit that determines whether the first escape section ES1 and the second escape section ES2 are full of conveyed defective sheets will be described with reference to Fig. 8. Note that the first escape section ES1 and the second escape section ES2 have common specifications, and therefore will be simply referred to as "escape section ES" in the following description.

[0051] The escape section ES of this embodiment is equipped with a box-shaped discharge tray 60 with an open top, and is structured so that defective sheets are dropped and discharged onto this discharge tray 60, so the discharge amount varies depending on the size of the defective sheets. For this reason, the full state of the escape section ES is detected by counting the number of defective sheets discharged to the escape section ES, which is determined by the size. In other words, the number of defective sheets of a predetermined size that fills the escape section ES is measured in advance to determine an upper limit (full value), and sizes larger than the predetermined size are counted as two. For example, if the predetermined size is A4, A4, A5, and A6 are counted as one count (equivalent to one sheet), and B4 and A3 are counted as two counts (equivalent to two sheets).

[0052] The full-state detection means is executed when a defective sheet is detected by the multiple feed sensors DFS1 to DFS3 and multiple feed processing is started by the first paper feed unit DK1 or the second paper feed unit DK2. First, it is detected whether a defective sheet has been discharged to the escape section ES (ST11). Specifically, whether a defective sheet has been discharged is determined depending on whether the sheet sensor S10 arranged in the escape section ES detects a defective sheet.

[0053] When a sheet is detected, the image forming apparatus 101 acquires information (size) of the sheet via the first paper feed unit DK1 or the second paper feed unit DK2 (ST12). Then, from the acquired sheet information, it is determined whether the sheet size is equal to or smaller than a predetermined size (ST13). If it is equal to or smaller than the predetermined size, it is determined whether it is a defective sheet or a first-out sheet, and if it is a defective sheet, it is determined that two sheets were transported and discharged overlapping each other, and "2" is added to the full counter CN (ST14, ST16).

[0054] On the other hand, if it is a first-out sheet, "1" is added to the full counter CN (ST14, ST17). If the sheet is a large size (L size) larger than the specified size, it is determined whether it is a defective sheet or a first-out sheet, and it is determined that an L-size sheet has been double-fed, and "4" is added to the full counter CN (ST15, ST18). On the other hand, if it is an L-size first-out sheet, "2" is added to the full counter CN (ST15, ST19). Note that in the multiple feed processing of this embodiment, the defective sheet is transported and discharged first, so the first sheet discharged after the detection of a defective sheet is regarded as the defective sheet, and subsequent sheets are regarded as first-out sheets.

[0055] Next, the incremented count value of the full counter CN is compared with a preset full value, and if it is equal to or greater than the full value, it is determined that the escape section ES is full, and the full flag FUPLG is set to "1" (ST20, ST21). On the other hand, if the count value of the full counter CN is smaller than the preset full value, it is determined that the escape section ES is not full (ST20). The full flag FUPLG can be set to be reset (full flag FUPLG is set to "1"), for example, by detecting the opening and closing of an opening / closing cover (not shown) covering the escape section SE. In other words, it can be determined that all defective sheets discharged to the escape section ES have been removed by the opening and closing operation of the opening / closing cover.

[0056] As shown in the above embodiment, in the escape section ES having a box-shaped discharge tray that discharges sheets by dropping them, a number of different types of sheets may be discharged, so weighting (coefficients) may be set according to the size, thickness, material, etc. of the sheets, and a full load of sheets may be detected based on the number of sheets and the weighting. Furthermore, a means may be used in which an optical sensor is disposed in the escape section ES to detect a full load of sheets, or a means may be used in which a mechanical sensor lever is provided on the upper part of the escape section ES and the operation of this sensor lever is detected by an optical sensor. [Explanation of symbols]

[0057] DK Paper Feeder DK1 1st feed unit (downstream feed unit) DK2 2nd feed unit (upstream feed unit) CON0, CON1, CON2 Control section (control means) ES1 First escape section (downstream discharge section) ES2 Second escape section (upstream discharge section) M1~M14 Conveyor motor M15~M17 Lift motor S1~S13 Sheet sensors DFS1 to DFS3 Double feed sensor (Means for detecting defective sheets) TR1~TR5 Transport route TR6 connection path J1 Junction TP Through Pass Section FL1, FL2 Flappers LO1, LO2, LO3 Storage unit (storage section) 19 Discharge roller pair 20 Paper feed section 21 Paper feed cassette 22 Pickup roller 25 Separation and conveying roller pair 29 Output Tray 31 Transport roller pair 33 Registration roller pair 34 Sheet transport path 39 Conveyor roller pair 40a, 40b, 40c Sheet feeding section 41a Separation and conveyance roller pair 42a conveying roller pair 43a Pickup roller 44a, 44b, 44c Loading Tray 45a, 45a, 45c Lifting mechanism 50 Conveyor 51-54 Conveyor roller pair 60 Output Tray 100 Image forming system 101 Image forming device 102 Operation section 103 Display Department

Claims

1. an upstream paper feed unit having a transport path that guides a sheet in a predetermined transport direction; a downstream paper feed unit provided downstream of the upstream paper feed unit in the transport direction and having a transport path for guiding the sheet transported from the upstream paper feed unit; an upstream discharge section provided in the upstream paper feed unit and configured to discharge defective sheets generated in the transport path; a downstream discharge section provided in the downstream paper feed unit and configured to discharge defective sheets generated in the transport path; an upstream side fullness detection means for detecting a full state of the defective sheets discharged to the upstream side discharge section, the upstream side paper feed unit has an upstream side control means for discharging the defective sheet in the upstream side paper feed unit to the upstream side discharge section, and for conveying the defective sheet to the downstream side paper feed unit when the upstream side fullness detection means detects that the upstream side discharge section is full; The downstream side paper feeding unit has a downstream side control means for discharging the defective sheet conveyed to the downstream side paper feeding unit by the upstream side control means to the downstream side discharge section.

2. a downstream side fullness detection means for detecting a full state of the defective sheets in the downstream side discharge portion; 2. The paper feeding device according to claim 1, further comprising an informing means for informing a full state of the downstream discharge portion when the downstream full state detecting means detects the full state of the downstream discharge portion.

3. a defective sheet detection unit for detecting the defective sheet, 3. The paper feeding device according to claim 1, wherein the control means discharges any sheet remaining in the transport path to the upstream discharge section at the time when the defective sheet detection means detects a defective sheet, and discharges the remaining sheet to the downstream discharge section when the upstream full detection means detects that the upstream discharge section is full.

4. a first feeding device having a first storage section in which sheets are stored, a first feeding means for feeding the sheets stored in the first storage section, and a first transport path for guiding the sheets fed by the first feeding means; a second feeding device having a second storage section in which sheets are stored, a second feeding means for feeding the sheets stored in the second storage section, and a second transport path for guiding the sheets fed by the second feeding means, the second transport path being a second transport path along which the sheets fed from the first feeding device are transported; a first discharge unit provided in the first feeding device and configured to discharge a sheet that has experienced a conveyance error on the first conveyance path; a second discharge unit provided in the second feeding device and configured to discharge a sheet that has experienced a conveyance error on the second conveyance path; a detection unit for detecting whether the number of sheets discharged to the first discharge unit is equal to or greater than a predetermined number; a control unit that controls the sheet having a transport failure on the first transport path to be discharged to the second discharge unit when the detection unit detects that the amount of the sheet discharged to the first discharge unit is equal to or greater than a predetermined amount; A sheet feeding system comprising:

5. Further comprising a double feed detection means for detecting a double feed state of the sheets, When the double feed detection unit detects the double feed state, the control unit discharges the sheet remaining in the first transport path together with the sheet in the double feed state to the second discharge unit.

5. The sheet feeding system according to claim 4.

6. The first discharge section is provided vertically below the first conveying path, The second discharge section is provided vertically below the second transport path.

6. The sheet feeding system according to claim 4, wherein the sheet feeding device is a sheet conveying device.

7. A sheet feeding system according to any one of claims 4 to 6, an image forming apparatus for forming an image on a sheet fed from the sheet feeding system; An image forming system comprising:

Images