Sheet paper feeding device and image formation device

Abstract

To provide a sheet paper feeding device and an image formation device that can detect paper abnormalities at initial stages and remove jammed paper without stopping printing operation, thereby reducing machine downtime.SOLUTION: A device according to the present invention includes a paper stacking part, a conveying part that sucks and conveys paper from the paper stacking part, a sensor part that detects the condition of paper before it is conveyed from the paper stacking part, a determination part that determines whether the paper is abnormal based on the detection result of the sensor part, and a switching part that switches the paper conveyance path based on the determination result of the determination part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device and an image forming apparatus. [Background technology]

[0002] If the paper loaded into the paper feeder is of poor quality (folded, torn, etc.), the paper will collide with the transport path during printing and cause a jam. If a jam occurs during printing, the machine will have to perform downtime to remove the paper and resume printing. For this reason, it is important to detect the paper condition that causes a jam and remove abnormal paper beforehand. For example, Patent Document 1 discloses a control configuration that uses a light source and optical lens to detect the paper condition based on the amount of movement of emitted light and reflected light, and determines that the paper is being transported abnormally, with the aim of detecting the condition of the paper being transported and preventing jams. Summary of the Invention [Problem to be solved by the invention]

[0003] However, although the above technology has a means for detecting the state of paper during printing, if abnormal paper is detected, the printing operation must be stopped and the operator must open the machine exterior and manually remove any paper remaining in the transport path.As a result, although it does not result in a jam abnormality, the need to temporarily halt printing and remove the paper inevitably results in machine downtime during which printing cannot be performed.

[0004] The present invention has been made in consideration of the above, and aims to provide a sheet feeding device and an image forming device that can detect abnormal paper at an early stage and remove jammed paper without stopping printing operations, thereby reducing machine downtime. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a paper stacking unit, a transport unit that adsorbs and transports paper from the paper stacking unit, a sensor unit that detects the state of the paper before it is transported from the paper stacking unit, a judgment unit that judges whether the paper is abnormal based on the detection result of the sensor unit, and a switching unit that switches the paper transport path based on the judgment result of the judgment unit. [Effects of the Invention]

[0006] According to the present invention, it is possible to detect abnormal paper at an early stage and remove the jammed paper without stopping the printing operation, thereby reducing machine downtime. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a side view showing the overall configuration of a printing system according to this embodiment. [Figure 2] FIG. 2 is a side view showing the configuration of the connected type paper feeder according to the present embodiment. [Figure 3] FIG. 3 is a perspective view showing the configuration of the air sheet feeding device according to this embodiment. [Figure 4] FIG. 4 is a conceptual diagram showing a side configuration of the air sheet feeding device according to this embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the hardware configuration of the air paper feeder included in the printing system according to the present embodiment. [Figure 6] FIG. 6 is a diagram showing an example of the functional configuration of the air paper feeding device included in the printing system according to this embodiment. [Figure 7] FIG. 7 is a diagram for explaining an example of a method for detecting the state of paper in the air paper feeder included in the printing system according to this embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of the flow of a process for switching the transport path in the air paper feeder of the printing system according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a sheet feeding device and an image forming apparatus will be described in detail with reference to the accompanying drawings.

[0009] FIG. 1 is a side view showing the overall configuration of a printing system according to this embodiment. FIG. 2 is a side view showing the configuration of a connected paper feeder according to this embodiment. FIG. 3 is a perspective view showing the configuration of an air paper feeder according to this embodiment. FIG. 4 is a conceptual diagram showing the side configuration of an air paper feeder according to this embodiment. As shown in FIG. 1, a printing system 1 according to this embodiment includes an image forming apparatus 2 and connected paper feeders 5a and 5b.

[0010] Image forming device 2 is a digital multifunction peripheral equipped with device main body 2M having paper feed unit 3 and image forming unit 4. Device main body 2M has control unit 20 that controls image forming device 2 and connected paper feed devices 5a and 5b. Device main body 2M is provided with operation display unit 25 on the top surface, which is composed of a touch panel or the like, that displays various information and allows various input operations to be made to control unit 20, such as starting execution of a print job.

[0011] 1, the paper feed unit 3 has multiple paper feed cassettes 31A, 31B, and 31C each capable of storing cut-sheet paper P (recording paper: for example, blank paper) in a stacked state. Each of the paper feed cassettes 31A, 31B, and 31C stores paper P of a sheet size selected in advance from a plurality of sheet sizes, for example, in a vertical or horizontal paper feed direction.

[0012] The paper feed section 3 has paper feed devices 30A, 30B, and 30C that sequentially pick up and separate the paper sheets P stored in paper feed cassettes 31A, 31B, and 31C from the top layer. The paper feed section 3 is further provided with various rollers 32 and the like, which form a paper feed path 33 that transports the paper sheets P fed from the paper feed devices 30A, 30B, and 30C to a predetermined image forming position in the image forming section 4.

[0013] Image forming section 4 includes exposure devices (exposure units) 41K, 41Y, 41M, and 41C, and photosensitive drums 42K, 42Y, 42M, and 42C. Image forming section 4 also includes developing devices 43K, 43Y, 43M, and 43C filled with black (K), yellow (Y), magenta (M), and cyan (C) toner. Image forming section 4 also includes a primary transfer section 44, a secondary transfer section 45, and a fixing section 46.

[0014] The exposure devices 41K, 41Y, 41M, and 41C are configured to generate laser light L for exposure of each color based on an image input from, for example, an external PC (personal computer), etc. The exposure devices 41K, 41Y, 41M, and 41C also expose the photosensitive drums 42K, 42Y, 42M, and 42C of each color with the laser light to form electrostatic latent images of each color corresponding to the read image on the surface of each photosensitive drum 42K, 42Y, 42M, and 42C.

[0015] The developing devices 43K, 43Y, 43M, and 43C supply a thin layer of toner to the corresponding photosensitive drums 42K, 42Y, 42M, and 42C so that the toner is brought into close proximity thereto, thereby developing the electrostatic latent image into a visible image with the toner.

[0016] The image forming unit 4 primarily transfers the toner images developed on the photosensitive drums 42K, 42Y, 42M, and 42C to a primary transfer unit 44, and then secondarily transfers the toner images onto paper P at a secondary transfer unit 45 located close to the primary transfer unit 44. The image forming unit 4 also heats and presses the toner images secondarily transferred onto paper P at a fixing unit 46 to melt the toner images, thereby fixing and recording a color image onto paper P.

[0017] The image forming unit 4 has a transport path 40 that transports the paper P, which has been transported from the paper feed unit 3 via the paper feed path 33, to the secondary transfer unit 45 side. The transport timing and transport speed of the paper P are adjusted along this transport path 40. The paper P passes through the secondary transfer unit 45 and the fixing unit 46 in a state synchronized with the belt speeds at the primary transfer unit 44 and the secondary transfer unit 45, and is then discharged onto the paper discharge tray 49.

[0018] Below the secondary transfer unit 45 and the fixing unit 46, a switchback conveying path 47 and a reversing conveying path 48, each of which is made up of a plurality of conveying rollers, conveying guides, etc., are disposed.

[0019] When forming images on both sides of a sheet of paper P, the switchback conveying path 47 is configured to perform switchback conveyance by entering the sheet of paper P, on which an image has been fixed on any one side, from one end, and then moving it backward (in the opposite direction from when it entered).

[0020] The reverse conveying path 48 reverses the front and back of the sheet P conveyed in a switchback manner by the switchback conveying path 47C, and feeds the sheet to the conveying path 40 again.

[0021] After the image fixing process on one side of the sheet P is completed, the sheet P is reversed in its travel direction by the switchback conveyance path 47 and the reversing conveyance path 48, and then is turned over and enters the secondary transfer nip again. The sheet P then undergoes the secondary image transfer process and fixing process on the other side, and is then discharged onto the discharge tray 49.

[0022] The image forming device 2 is capable of feeding paper P from the paper feed section 3 in the device main body 2M via the paper feed path 33 and the conveying path 40, as well as feeding paper P via the connected paper feed devices 5a and 5b via the connecting passage 500 provided on the side of the device main body 2M.

[0023] In the printing system 1, the tethered paper feeders 5a and 5b are each configured as the tethered paper feeder 5 shown in FIG. 2. As shown in FIG. 2, the tethered paper feeder 5 has two paper feed trays 51, a connecting paper transport path 503 connecting connecting paths 501 and 502, and paper transport paths 504 and 505 connecting the paper feed trays 51 and the connecting path 501, respectively. The tethered paper feeder 5 is configured to be connectable to the image forming apparatus 2 so that the connecting path 501 connects to the connecting path 500 (see FIG. 1) of the image forming apparatus 2. The tethered paper feeder 5 can also be connected to another tethered paper feeder 5 so that the connecting path 502 connects to the connecting path 501 of the other tethered paper feeder 5.

[0024] 1 includes connected paper feeders 5a and 5b as external paper feeders that feed paper P to image forming apparatus 2. Connected paper feeder 5a transports paper P loaded in each paper feed tray 51 via either paper transport path 504 or 505, and sends the paper P to transport path 40 via connecting passage 500 of image forming apparatus 2.

[0025] The connected type paper feeder 5b transports the paper P loaded in each paper feed tray 51, 51 within its own device via either paper transport path 504 or 505. Furthermore, the connected type paper feeder 5b sends the paper P via the connected paper transport path 503 of the connected type paper feeder 5a and the connected passage 500 of the image forming apparatus 2 to the transport path 40.

[0026] In the printing system 1, the image forming apparatus 2 and the linked paper feeders 5a and 5b are electrically connected when linked, and the paper feed operation for the paper P is performed under the control of the control unit 20.

[0027] 2, the configuration of the connected paper feeder 5 will be described. In the connected paper feeder 5, each paper feed tray 51 has a tray bottom plate 52, side fences 53 and 54, an end fence 55, a lifting mechanism 56, and a lifting motor 57.

[0028] In the paper feed tray 51, a tray bottom plate 52 carries a plurality of sheets P. The tray bottom plate 52 is configured to be able to move up and down via an elevator mechanism 56 driven by an elevator motor 57 (described later) with the sheets P loaded as a paper stack. The tray bottom plate 52, the elevator mechanism 56, and the elevator motor 57 constitute the elevator means of the present invention.

[0029] In paper feed tray 51, side fences 53 and 54 restrict the movement of paper sheets P stacked on tray bottom plate 52 in the width direction. End fence 55 is provided at the rear end, in the paper transport direction, of paper sheets P stacked on tray bottom plate 52, and restricts the movement of paper sheets P in the direction opposite to the paper transport direction. Elevating mechanism 56 is connected between tray bottom plate 52 and elevator motor 57, and can raise and lower tray bottom plate 52, and therefore paper sheets P on tray bottom plate 52, by rotating and driving elevator motor 57.

[0030] The linked paper feeder 5 is provided with an air pickup type paper feeder, i.e., an air paper feeder 60, which blows air into a stack of paper P stored in each paper feed tray 51, 51 to float and separate the paper P, and then sucks the paper P one by one with air and sends it to paper transport paths 504, 505.

[0031] As shown in FIGS. 2 to 4, air paper feeder 60 is made up of tray bottom plate 52, side fences 53, 54 and end fence 55 that constitute paper feed tray 51, air paper feed unit 58 and belt paper feed unit 59.

[0032] The air paper feed unit 58 is disposed downstream of the tray bottom plate 52 in the paper transport direction, and has a floating fan 58a and a separation fan 58b as blower fans that blow air onto the paper P from the front edge side in the width direction perpendicular to the paper transport direction. The floating fan 58a and the separation fan 58b blow air onto the stack of paper P from the front edge side in the width direction, causing paper P in a predetermined area below the top of the paper P to float and separate.

[0033] The side fence 53 of the paper feed tray 51 is provided with a side fan 53a as a blower fan that blows air from the side of the paper P. Similarly, the side fence 54 is provided with a side fan 54a as a blower fan that blows air from the opposite side of the paper P. The side fans 53a and 54a blow air onto the stack of paper P from both sides, making it easier for the paper P to float and separate.

[0034] As shown in FIGS. 3 and 4, the belt feeding unit 59 includes air suction fans 59a and 59b, a suction duct 59c, a suction chamber 59d, a pair of delivery rollers 59e and 59f, and a suction belt 59g.

[0035] The air suction fans 59a and 59b suck air from the suction chamber 59d through a suction duct 59c whose opening faces the top surface of the uppermost sheet P of the stack of sheets P stacked on the tray bottom plate 52. The air suction fans 59a and 59b are equipped with air filters 591a and 591b that remove paper powder, calcium carbonate, dust, and dirt so that they are not discharged outside the machine.

[0036] The suction belt 59g is configured as an endless belt made of, for example, rubber, stretched between a pair of feed rollers 59e, 59f facing the opening of the suction chamber 59d. The sheet P is adsorbed onto the suction belt 59g by air sucked in by air suction fans 59a, 59b. The pair of feed rollers 59e, 59f are driven to rotate by a belt drive motor 59h, which will be described later, and transport the suction belt 59g, to which the sheet P is adsorbed, downstream in the paper transport direction.

[0037] With the above-described configuration, in the belt paper feed unit 59, the sheets P that have been floated and separated by the air blown from the air paper feed unit 58 are sucked in through the suction duct 59c, and then the sheets P are sucked in one by one, starting from the top, onto the suction belt 59g. Thereafter, in the belt paper feed unit 59, the pair of feed rollers 59e, 59f are rotationally driven to rotate the suction belt 59g, and the sheets P sucked onto the circumferential surface of the suction belt 59g are fed downstream in the paper conveyance direction.

[0038] In the air paper feeder 60, in controlling the paper feed operation of the paper P, the side fans 53a, 54a, the floating fan 58a, the separation fan 58b, and the air suction fans 59a, 59b are selectively driven to rotate at their respective start timings in accordance with the paper feed timing.

[0039] In the air paper feeder 60, when the floating fan 58a and the separation fan 58b start to rotate, the air generated by their rotation is blown onto the leading edge of the paper P through different duct paths as separation air for separating the paper P and floating air for floating the entire stack of paper.

[0040] In air sheet feeder 60, when side fans 53a and 54a provided on side fences 53 and 54, respectively, start to rotate, side air is blown onto the sides of sheets P, and the entire stack of sheets floats up in the same way as with floating fan 58a.

[0041] In the air sheet feeding device 60, when the air suction fans 59a and 59b start to rotate, the suction air passes through the suction duct 59c and creates a negative pressure in the suction chamber 59d in the belt sheet feeding unit 59, thereby sucking in the top sheet P of the stack of sheets P. When the top sheet P is adsorbed to the suction belt 59g, the suction belt 59g is driven to rotate, and the sheet P is transported to the device main body 2M of the image forming device 2.

[0042] In the above paper feeding operation, the air volume of side fans 53a, 54a, lifting fan 58a, separation fan 58b, and air suction fans 59a, 59b and the switching between air blowing and shutting off are automatically controlled by control unit 20 by determining paper feeding parameters based on the paper type, paper thickness, and paper size.

[0043] 5 is a diagram illustrating an example of the hardware configuration of an air paper feeder included in a printing system according to this embodiment. Air paper feeder 60 (an example of a sheet feeder) according to this embodiment is characterized by an air pick belt (suction belt 59g) that sucks and transports paper P (an example of paper), which is the paper to be transported, two types of sensors (distance sensors S1 and S2, optical sensors S3 and S4) that detect the state (paper state) of paper P, a mechanical transport mechanism (motor M, path changing plate 511) that changes the transport path of paper P, and a control board 21 that controls the transport of paper P in air paper feeder 60.

[0044] Because folded or torn paper P may physically collide with rollers during transport, an air pick belt (suction belt 59g) is used, which can transport the paper by air suction. Because paper creases and other abnormalities are particularly likely to occur at the four corners of the paper P, various sensors are placed at the four corners of the paper P to detect the paper condition. Conventional paper condition detection (optical sensors, pressure sensors, etc.) can only accurately detect paper P when it is being transported stably, making it difficult to accurately detect the front portion of the paper P (the front portion of the paper P in the transport direction) that is floating on the air pick belt (suction belt 59g). Therefore, in this embodiment, optical sensors S3 and S4 (or others are possible) are used, which can accurately detect the rear portion of the paper P (the rear portion of the paper P in the transport direction), as in the past, and distance measuring sensors S1 and S2 are used at the front portion of the paper P, allowing for a simple determination of abnormal paper condition.

[0045] 6 is a diagram showing an example of the functional configuration of an air paper feeder 60 included in a printing system according to this embodiment. As shown in FIG. 6, the air paper feeder 60 according to this embodiment includes a determination unit 601, a conveyance unit 602, a sensor unit 603, and a paper stacking unit 604.

[0046] The paper stacking unit 604 is an example of a paper stacking unit where paper sheets P are stacked, such as the sheet bottom plate 52. The transport unit 602 is an example of a transport unit that adsorbs and transports paper sheets P from the paper stacking unit 604, such as an air pick belt (adsorption belt 59g) that can adsorb and transport paper sheets P. As a result, if folded or torn paper sheets P are transported using rollers, they may physically collide and cause jams, so by using an air pick belt that can adsorb and transport the paper sheets P using the belt, it is possible to transport abnormal paper sheets.

[0047] The sensor unit 603 is an example of a sensor unit, such as distance sensors S1 and S2 and optical sensors S3 and S4, that detects the state of paper P before it is conveyed from the paper stacking unit 604. Specifically, the sensor unit 603 detects the state of paper when the paper P is picked up in the paper stacking unit 604 and separated from the second sheet. More specifically, the sensor unit 603 detects the state of paper stacked in the paper stacking unit 604 from the time the conveying unit 602 picks up the paper P until the conveying switch unit 602a, described below, is reached. This makes it possible to prevent errors such as jams by detecting the state of paper before it is conveyed by the rollers. The sensor unit 603 is also provided on the tray bottom plate 52, and at least one of the sensors may be the distance sensor S1. This makes it possible to detect the state of paper even when the paper P is in an unstable state due to an air pick. Furthermore, the sensor unit 603 may be provided at positions corresponding to the four corners of the paper P, with optical sensors S3 and S4 on the upstream side in the paper transport direction and distance measuring sensors S1 and S2 on the downstream side in the transport direction. In this way, by placing a conventional optical sensor on the upstream side in the transport direction of the paper P, it is possible to detect the step of the paper fold with high accuracy and determine the paper condition.

[0048] The determination unit 601 is an example of a determination unit that determines an abnormality in the paper P based on the detection result of the sensor unit 603. The transport unit 602 has a transport switching unit 602a. The transport switching unit 602a has a path changing plate 501 and the like, and switches the transport path of the paper P based on the determination result of the determination unit 601. This allows the system to detect the paper condition during printing operation and before the paper is transported, and if an abnormal paper is detected, it does not transport the paper along the normal transport route and has the function of removing the abnormal paper, making it possible to eliminate paper that may cause a transport abnormality in advance without stopping the printing operation. As a result, machine downtime can be reduced by detecting abnormal paper at an early stage and removing the jammed paper without stopping the printing operation.

[0049] The overall functional flow of air paper feeder 60 is as follows: sensor unit 603 (distance measuring sensors S1, S2) detects the paper condition of paper P (conveyed paper) stacked in paper stacking unit 604 (tray bottom plate 52, etc.), and judgment unit 601 judges the paper condition (for example, whether the paper is folded or not) based on that data. Next, air paper feeder 60 conveys paper P while conveyance switching unit 602a of conveyance unit 602 switches the conveyance path for paper P in accordance with instructions from judgment unit 601 based on the paper condition judgment result, such as whether paper P is folded or not. Therefore, for paper P for which an abnormality is detected (abnormal paper), the conveyance path for normal paper P (normal paper conveyance path) is automatically switched to the abnormal paper conveyance path (abnormal paper conveyance path), allowing printing operations to continue without stopping paper conveyance.

[0050] Fig. 7 is a diagram for explaining an example of a method for detecting the paper condition in the air paper feeder of the printing system according to this embodiment. Specifically, Fig. 7 is a diagram for explaining an example of a method for detecting the paper condition using distance measuring sensors S1 and S2 included in sensor unit 603.

[0051] First, we will explain the operation when the paper P is in a normal state (normal paper). Initially, because the paper P is stacked, the distance between the paper P (stacked paper) and the distance measuring sensors S1 and S2 is at its maximum. Here, the paper holder (tray bottom plate 52) moves up and down, and the distance between the stacked paper and the distance measuring sensors S1 and S2 is always maintained at a constant distance (timing (1)). Next, the paper P is floated by the air pick belt (suction belt 59g), and the distance between the stacked paper and the distance measuring sensors S1 and S2 becomes shorter (timing (2)). Then, the paper P is transported when it is completely floated (i.e., the distance between the distance measuring sensors S1 and S2 and the paper P is at its minimum), and after transporting one sheet of paper P, the state returns to timing (1) (timing (3)).

[0052] In the case of abnormal paper, even if the front part of the paper P floats up at timing (2), the paper P is not present at the reading position of the distance measuring sensors S1 and S2 due to an abnormality (for example, a folded paper), so the distance between the stack of paper and the distance measuring sensors S1 and S2 does not change. Therefore, it is possible to determine whether or not there is an abnormality in the paper P from the data acquired by the distance measuring sensors S1 and S2 during transportation (the status data at timing (2)).

[0053] 8 is a flowchart showing an example of the flow of the conveyance path switching process in the air paper feeder of the printing system according to this embodiment. When paper conveyance begins, air paper feeder 60 starts detecting the paper condition of paper P using sensor unit 603 (step S801). Next, suction belt 59g picks paper P from paper stacking unit 604 (step S802). Thereafter, suction belt 59g conveys the picked up paper P (step S803). Next, determination unit 601 determines whether the paper condition is normal or not based on the paper condition detection result by sensor unit 603 (step S804). Specifically, determination unit 601 determines whether the distance between paper P and distance measuring sensors S1 and S2 is equal to or less than a threshold at timing (2).

[0054] If it is determined that the paper condition is normal (step S804: Yes), the transport switching unit 602a of the transport unit 602 moves the path changing plate 511 upward (step S805) and transports the paper with rollers (step S806). After that, the image forming unit 4 prints an image on the paper (step S807) and stacks it in the paper storage area for normal paper (step S808).

[0055] On the other hand, if it is determined that the paper condition is abnormal (step S804: No), the transport switching unit 602a moves the path change plate 511 downward (step S809), transports the paper P using the suction belt 59g (step S810), and stacks it in the paper storage area for abnormal paper (step S811).

[0056] In this way, with the air paper feeder 60 according to this embodiment, the path change plate 511 is moved based on the results of detecting the paper condition just before the paper P is transported. If the paper condition is normal, the paper is transported to the regular transport path using transport rollers as before, but if the paper condition is abnormal, the air pick belt is used to automatically sort the paper into the abnormal transport path. As described above, by detecting the paper condition in the early stages of printing and immediately changing the transport path based on the paper condition detection results, it is possible to prevent abnormalities such as jams without stopping the printing operation, and to eliminate machine downtime caused by abnormal paper.

[0057] In the above embodiment, the image forming apparatus of the present invention is described as being applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function, but the present invention can be applied to any image forming apparatus such as a copier, printer, scanner device, or facsimile device.

[0058] For example, aspects of the present invention are as follows. <1> a paper stacking unit; a conveying unit that adsorbs and conveys paper from the paper stacking unit; a sensor unit that detects the state of the paper before the paper is conveyed from the paper stacking unit; a determination unit that determines whether the paper is abnormal based on the detection result of the sensor unit; a switching unit that switches the paper transport path based on the determination result of the determination unit; A sheet feeding device comprising: <2> The sensor unit detects the state of the paper when the paper is picked up in the paper stacking unit and separated from the second sheet. <1> The sheet feeding device according to claim 1. <3> The sensor unit detects the state of the paper stacked in the paper stacking unit from the time when the paper is adsorbed by the transport unit to the switching unit. <1> or <2> The sheet feeding device according to claim 1. <4> The sensor units are provided in the paper stacking unit, and at least one of the sensor units is a distance measurement sensor. <1> from <3> 10. The sheet feeding device according to claim 9, wherein <5> The sensor units are provided at positions corresponding to the four corners of the paper, and an optical sensor is provided upstream in the paper transport direction, and a distance measurement sensor is provided downstream in the paper transport direction. <1> from <4> 10. The sheet feeding device according to claim 9, wherein <6> The conveying unit is an air pick belt that can adsorb and convey paper. <1> from <5> 10. The sheet feeding device according to claim 9, wherein <7> <1> from <6> 10. An image forming apparatus comprising the sheet feeding device according to claim 19. [Explanation of symbols]

[0059] 1 Printing System 2. Image forming device 5a,5b Connected paper feeder 52 Tray bottom plate 59g suction belt 60 Air paper feeder 511 Route change board 601 Judgment section 602 Conveyor 603 Sensor unit 604 Paper stacking section S1, S2 distance measurement sensors S3, S4 optical sensors Medium motor [Prior art documents] [Patent documents]

[0060] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-089943

Claims

1. a paper stacking unit; a conveying unit that adsorbs and conveys paper from the paper stacking unit; a sensor unit that detects the state of the paper before the paper is conveyed from the paper stacking unit; a determination unit that determines whether the paper is abnormal based on the detection result of the sensor unit; a switching unit that switches the paper transport path based on the determination result of the determination unit; A sheet feeding device comprising:

2. 2. The sheet feeding device according to claim 1, wherein the sensor detects the state of the paper when the paper is picked up in the paper stacking section and separated from the second sheet.

3. 3. The sheet feeding device according to claim 1, wherein the sensor detects the state of the paper stacked in the paper stacking section from the time when the paper is attracted by the transport section to the time when the paper is switched.

4. 3. The sheet feeding device according to claim 1, wherein the sensor units are provided in the sheet stacking unit, and at least one of the sensor units is a distance measuring sensor.

5. 3. The sheet feeding device according to claim 1, wherein the sensor unit is provided at positions corresponding to four corners of the paper, the sensor unit being an optical sensor on the upstream side in the paper transport direction and a distance measuring sensor on the downstream side in the transport direction.

6. 3. The sheet feeding device according to claim 1, wherein the transport unit is an air pick belt capable of suction-carrying and transporting paper.

7. An image forming apparatus comprising the sheet feeding device according to claim 1 or 2.

Images