Sheet loading device and image forming device

Abstract

To provide a sheet loading device that prevents a sheet from flowing downstream in a conveying direction from a sheet loading position.SOLUTION: A sheet loading device includes: a loading table on which a sheet bundle is loaded; a conveyance mechanism that conveys a sheet in a conveyance direction toward the loading table; and a guide member that holds a tip end part of the sheet conveyed by the conveyance mechanism at a standby position and then moves in the conveyance direction of the sheet to guide conveyance of the sheet. The sheet loading device uses a speed difference between a sheet conveyance speed of the conveyance mechanism and a moving speed of the guide member to separate the tip end part of the sheet held by the guide member from the guide member at a separation position, and drops the separated sheet onto the loading table for loading. The sheet loading device further includes a tip alignment mechanism for aligning a tip position of the sheet on the loading table in the conveyance direction, and the tip alignment mechanism includes a partition member extending onto a moving path of the guide member.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a sheet stacking device and an image forming apparatus using the same. [Background technology]

[0002] 2. Description of the Related Art In an image forming apparatus employing an electrophotographic system, a sheet stacking device that stacks conveyed sheets as a sheet bundle is widely known. It is known that in such sheet stacking devices, curls in the sheet stack transported to the stacking tray can hinder the transport of the sheets, causing jams when the subsequently discharged sheets move from the transport member to the stacking tray. As a countermeasure against this, a technique is known in which a sheet trailing end pressing means is provided that strikes the trailing end of a falling sheet toward the stacking tray (see, for example, Patent Document 1).

[0003] In addition, a sheet stacking device is known in which a guide member that transports the sheet while holding the leading edge of the sheet being transported moves at the same speed as the sheet transport speed, while a transport member sends out the trailing edge of the sheet to transport and stack the sheet at a stacking position. In such a sheet stacking device, the speed difference between the sheet conveying speed of the conveying member and the sheet conveying speed of the guide member is used to separate the sheet gripped by the guide member from the guide member, and the separated sheet is dropped onto a tray for stacking (see, for example, Patent Documents 2 and 4). In this technology, the guide member is accelerated just before it reaches the sheet stacking position, thereby further increasing the conveying speed difference with the sheet being conveyed by the conveying member, and the leading edge of the sheet is reliably separated from the guide member. The sheet whose leading edge has separated from the guide member falls freely onto the stacking tray for stacking.

[0004] Also known is a configuration that includes a leading edge alignment mechanism that aligns the position of the sheet edge by pushing the edge of the sheet loaded on the stacking tray with a plate that can move in the width direction or the conveying direction (see, for example, Patent Document 3, etc.). Summary of the Invention [Problem to be solved by the invention]

[0005] In the sheet stacking device having the above-mentioned configuration, a technique is conceivable in which a guide member for holding the leading edge of a sheet and a leading edge alignment mechanism are used in combination. According to this technique, the guide member can drop the sheet to a predetermined stacking position, and the position of the leading edge of the sheet, which tends to vary to a certain extent due to free fall, can be aligned.

[0006] However, with the above-described configuration, if the guide member fails to separate the sheet from the stacking position, problems may arise such as the guide member pulling the sheet downstream in the transport direction, or the guide member gripping the subsequent sheet colliding with an already stacked sheet, causing a jam. When a sheet jams due to a collision between the guide member and the sheet, the guide member moves downstream in the conveying direction, and may move to a position that is difficult for an operator to remove, so there was a need to solve this problem. SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a sheet stacking device that solves the above-mentioned problems and prevents sheets from flowing downstream in the transport direction from the sheet stacking position. [Means for solving the problem]

[0007] The sheet stacking device of the present invention comprises a loading platform on which a stack of sheets is loaded, a transport mechanism which transports sheets in a transport direction toward the loading platform, and a guide member which holds the leading edge of the sheet transported by the transport mechanism at a standby position and then moves in the transport direction of the sheet to guide the transport of the sheet, and uses the speed difference between the sheet transport speed of the transport mechanism and the moving speed of the guide member to detach the leading edge of the sheet held by the guide member from the guide member at a detachment position, and drops the detached sheet onto the loading platform for loading, and is characterized in that it has a leading edge alignment mechanism for aligning the leading edge position of the sheet on the loading platform in the transport direction, and the leading edge alignment mechanism has a partition member extending onto the movement path of the guide member. Effect of the Invention

[0008] According to the present invention, it is possible to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an image forming apparatus to which an embodiment of the present invention can be applied; [Diagram 2] FIG. 1 is a diagram illustrating an example of a configuration of a sheet stacking device according to an embodiment of the present invention. [Diagram 3] 4 is a schematic view of the sheet stacking device when the holding member is at the standby position, as viewed from above; FIG. [Figure 4] FIG. 2 is a block diagram of a control unit used in the sheet stacking device. [Diagram 5] 1 is a diagram illustrating an example of a sheet stacking device in a state in which a leading edge of a sheet has entered a holding member; [Figure 6] FIG. 13 is a diagram showing a state in which the transfer sheet has been detached from the holding member. [Figure 7] 13A and 13B are diagrams illustrating a state in which the small size sheet is released from the holding member. [Figure 8] 11A and 11B are schematic diagrams illustrating an example of a leading edge alignment operation of the sheet stacking device. [Figure 9]11A and 11B are schematic diagrams illustrating an example of an alignment operation in the width direction of the sheet stacking device. [Figure 10] FIG. 13 is a diagram illustrating a comparative example of a conventional sheet stacking device. [Figure 11] 11 is a diagram illustrating an example of a problem in the comparative example illustrated in FIG. 10. [Figure 12] 2 is a diagram illustrating an example of a configuration of a sheet stacking device according to an embodiment of the present invention, as viewed from a downstream side in a conveying direction. [Figure 13] 13A to 13C are diagrams illustrating the function of the partition member illustrated in FIG. 12. [Figure 14] FIG. 11 is a diagram showing an example of a configuration provided with a step-out detection function according to another embodiment of the present invention. [Figure 15] FIG. 13 is a diagram showing an example of a configuration in which a leading end aligning mechanism is provided with a function for detecting a distance traveled due to loss of synchronism, according to another embodiment of the present invention. [Figure 16] FIG. 13 is a diagram showing an example of a configuration in which a shift mechanism is provided with a function of detecting a distance traveled due to step-out, as another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 shows an image forming apparatus to which an embodiment of the present invention can be applied. In the figure, the image forming apparatus 1 has a sheet feeding device 110 that stores sheets S, which are recording media, a sheet position correction device 120 that corrects the position of the sheets S, and an image forming device 130 that forms an image on the sheets S. The image forming apparatus 1 also has a sheet drying device 140 for drying the formed image, a sheet cooling device 150, a sheet inverting device 160 for inverting the front and back of the sheet S, and, as the sheet stacking device of the present invention, a first sheet stacking device 170 for stacking the sheets S, a second sheet stacking device 180, and an operation unit 190 for controlling each of these parts based on instructions from an operator.

[0011] The sheet feeding device 110 and the sheet position correction device 120 are devices for conveying the sheets S, which are previously stacked and stored, one by one. For example, the sheet feeding device 110 is provided with a sheet size detection sensor 111 for detecting the size of the fed sheet S. A plurality of sheet size detection sensors 111 are provided so as to be able to detect the length and width of the sheet S. The sheet position correction device 120 adjusts the timing in accordance with the sheet size information from the sheet size detection sensor 111 so that an image of the image forming device 130 is formed at a predetermined position on the sheet S.

[0012] In this embodiment, the image forming device 130 is an inkjet recording device that ejects ink of four colors, black (K), cyan (C), magenta (M), and yellow (Y), to form a full-color image on the sheet S. The image forming device 130 has liquid ejection devices 132K, 132C, 132M, and 132Y of each color arranged around a main drum roll 131, and forms color images corresponding to C, M, Y, and K on the sheet S.

[0013] The sheet drying device 140 and the sheet cooling device 150 dry the inkjet image formed on the sheet S and then cool the sheet S, thereby allowing the inkjet image formed on the sheet S to be stably maintained on the paper surface.

[0014] The sheet inverting device 160 inverts the sheet S by a switchback method using each roller as necessary, and conveys the sheet S again to the sheet position correcting device 120 to switch the side on which the image is formed. Each of these units forms an image in such a manner that each device is appropriately controlled in response to an operation by an operator via an operation unit 190. In addition, in this embodiment, an inkjet printer that forms inkjet images has been described in particular, but the image forming device 130 may be, for example, an image forming device having an electrophotographic image forming section, and in that case, a fixing device that fixes the toner image onto the sheet S may be provided in place of the sheet drying device 140 and the sheet cooling device 150. The configuration of each device in the image forming apparatus 1 may be the same as that of a conventional image forming apparatus, and the description thereof will be omitted as appropriate.

[0015] As the sheet stacking device of the present invention, the first sheet stacking device 170 will be first described. The first sheet stacking device 170 and the second sheet stacking device 180 are multiple discharge destinations for sheets S in the image forming apparatus 1, and may have the same configuration or different configurations. In the embodiment of the present invention, the first sheet stacking device 170 and the second sheet stacking device 180 have the same configuration and differ only in the shape of the sheet discharge destination, and the first sheet stacking device 170 will be particularly described. The first sheet stacking device 170 has a sheet tray 5 as a loading platform, a transport mechanism 6 for transporting the sheet S to the sheet tray 5, a guide mechanism 7 that grasps the leading edge of the sheet S transported toward the sheet tray 5 and transports it toward the downstream side in the transport direction, a sheet leading edge detection sensor 8, and a bypass transport path 9 that transports the sheet S flowing from the upstream side in the transport direction to bypass the sheet tray 5 and transport it to the second sheet stacking device 180 located downstream in the transport direction.

[0016] A sheet tray 5 provided at the bottom of the first sheet stacking device 170 is a stacking table for stacking a plurality of sheets S after image formation. The sheet tray 5 is initially positioned below the sheets S fed by the conveying mechanism 6, and as the sheets S are piled up on the sheet tray 5, it moves downward, and the position of the top surface of the stack of stacked sheets is maintained at a height that allows the sheets S discharged from the conveying mechanism 6 to be easily stacked. The sheets S stacked on the sheet tray 5 are removed by the apparatus operator by pulling out the sheet tray 5 from the first sheet stacking device 170. The conveying mechanism 6, which conveys the sheet S sent from the imaging device 130 toward the sheet tray 5, is composed of a well-known roller pair consisting of a drive roller 6a and a driven roller 6b, and receives the sheet S discharged by a supply roller 171 arranged at the most upstream side of the first sheet stacking device 170, and conveys it downstream in the sheet conveying direction indicated by arrow A. The sheet leading edge detection sensor 8 is disposed on the upstream side of the conveying mechanism 6 in the sheet conveying direction A, and detects the leading edge of the conveyed sheet S and outputs a detection signal.

[0017] The guide mechanism 7, which is arranged downstream of the conveying mechanism 6 in the sheet conveying direction A, can hold the leading edge of the sheet S being conveyed by the conveying mechanism 6 and convey the sheet S toward the sheet conveying direction A at a speed faster than the sheet conveying speed of the conveying mechanism 6. The guide mechanism 7 thus holds the leading edge of the sheet S, and functions as a guide member that guides the conveyed sheet S onto the sheet tray 5 by moving away from the leading edge of the sheet S at the release position of the sheet S. The guide mechanism 7 has a runnable endless conveyor belt 10 stretched around a drive roller 12 and a driven roller 13, and a holding member 11 attached to the conveyor belt 10 and moving with the movement of the conveyor belt 10. The conveyor belt 10 is configured to have a variable running speed by controlling the operation of a motor 14 that drives the drive roller 12 by a control unit 50, which will be described later. The motor 14 is a variable speed stepping motor, and is configured to be able to grasp the position of the holding member 11 on the conveyor belt 10 from the number of steps. In this embodiment, as shown in FIG. 3, there are four conveyor belts 10 arranged parallel to each other in the width direction of the sheet S, and each of the conveyor belts 10a, 10b, 10c, and 10d has two holding members 11 arranged in point-symmetric positions with respect to each other. The holding member 11 is attached to the circumferential outer side of the conveyor belt 10 wound around the drive roller 12 and driven roller 13, and moves with the rotation of the conveyor belt 10. In other words, the "movement path of the holding member 11, which is a guide member" is a traveling path that is on the outer circumferential side of the conveyor belt 10, and a partition member 42, which will be described later, is disposed so as to be located on the movement path of the holding member 11 when viewed from the Y axis as shown in FIG.

[0018] The first sheet stacking device 170 uses the speed difference between the sheet conveying speed of the conveying mechanism 6 and the sheet conveying speed of the guide mechanism 7 to detach the sheet S held by the holding member 11 from the holding member 11 and stack the detached sheet S on the sheet tray 5. A blower fan 15 may be provided at a downstream portion of the guide mechanism 7 in the sheet conveying direction to apply an air flow to the conveyed sheet S toward the upper surface of the sheet tray 5, i.e., downward. The blower fan 15 is constantly operated to apply an air flow to the sheet S guided by the holding member 11 so as to press the sheet S toward the sheet tray 5.

[0019] 2, the holding member 11 has an opening 11a into which the leading edge of the sheet S is inserted, and a clamping portion 11b that clamps the leading edge of the sheet S inserted from the opening 11a. The force with which the clamping portion 11b clamps the leading edge of the sheet S is set to be smaller than the frictional force between the conveying mechanism 6 and the sheet S. Therefore, the clamping portion 11b allows the sheet S, which has been conveyed by the conveying mechanism 6 and inserted from the opening 11a, to enter the holding member 11 stopped at the standby position shown in FIG. 2 due to the rigidity of the sheet S, and holds the entered sheet S with its elasticity. The surface of the holding member 11 that comes into contact with the sheet S is preferably made of a material with high smoothness such as metal or resin, etc. This allows the sheet S to be held by the holding member 11 smoothly.

[0020] When the sheet S is received, the holding member 11 is stopped at the standby position shown in FIG. 2, and after the leading edge of the sheet S is detected by the sheet leading edge detection sensor 8 and the leading edge of the sheet S is clamped by the clamping portion 11b, the holding member 11 starts conveying the sheet S at a predetermined timing. In this manner, the holding member 11 holds the leading edge of the sheet S conveyed by the conveying mechanism 6 at the standby position, and then moves in the sheet conveying direction A to function as a guide member that guides the conveyance of the sheet S. 2 and 3, in the image forming apparatus 1, two holding members 11 are arranged on the outer circumferential surface of the conveyor belt 10 with their phases shifted by 180 degrees from each other. Therefore, when the conveyor belt 10 moves, once the conveyance of the sheet S is completed, the holding members 11 rotate half a revolution, and then the holding member 11 on the opposite side returns to the standby position and stops. In this manner, the two holding members 11 are alternately moved to the standby position, so that the time required for the holding members 11 to return to the standby position is shortened, and the conveying cycle of the sheet S can be improved.

[0021] 3, in the image forming apparatus 1, four conveyor belts 10 are provided in a sheet width direction B that is a direction perpendicular to a sheet conveying direction A, and two holding members 11 are arranged on each conveyor belt 10. As a result, compared to a configuration in which one or two conveyor belts 10 are provided with two holding members 11 per belt, the holding members 11 can be made smaller and the inertial load during running of the conveyor belt 10 can be reduced, and the increased number of holding members 11 can stabilize the holding posture of the sheet S.

[0022] The four conveying belts 10a, 10b, 10c, and 10d are classified into end belts 10a, 10d located at each end of the sheet width direction B, and central belts 10b, 10c arranged between the end belts 10a, 10d. The holding members 11 are arranged so that the end side belts 10a, 10d and the center side belts 10b, 10c are located at different positions in the sheet conveying direction A. Specifically, the holding members 11 arranged in the center side belts 10b, 10c are located at standby positions upstream in the sheet conveying direction A compared to the holding members 11 arranged in the end side belts 10a, 10d. With the above-mentioned configuration, the timing at which the sheet S is held by the holding member 11 can be shifted between the end side belts 10a, 10d and the center side belts 10b, 10c, thereby reducing the load when the sheet S enters the holding member 11. In addition, the timing at which the sheet S leaves the holding member 11 is also shifted, so that the sheet S can be kept in a stable position.

[0023] As shown in Fig. 3, the conveying mechanism 6 is composed of two roller pairs, each of which is the driving roller 6a and the driven roller 6b, and each roller pair is disposed in a striped manner so as to be positioned between each of the conveying belts 10a, 10b, 10c, and 10d. Note that, although the driving roller 6a connected to the driving source is disposed on the upper surface side of the sheet S in Fig. 3, the present invention is not limited to such a configuration.

[0024] At the downstream end of the sheet tray 5 in the sheet transport direction A, a leading edge aligning mechanism 40 is provided for abutting against the leading edge of the transported sheet S and aligning the leading edge of the sheet. The leading edge alignment mechanism 40 has an alignment guide plate 41 which is capable of reciprocating movement along the sheet transport direction A and which aligns the leading edge position of the sheet S by abutting against the leading edge, a partition member 42 which extends flush with the upper part of the alignment guide plate 41, and a base portion 43 which supports the alignment guide plate 41 and the partition member 42 so that they can reciprocate along the sheet transport direction A. The leading edge alignment mechanism 40 also has a leading edge alignment motor 45 attached to the base portion 43 for moving it back and forth in the A direction, and a leading edge alignment mechanism position detection sensor 44 . The leading edge alignment mechanism 40 has a shift mechanism 30 that supports the base portion 43 and changes the reference position of the base portion 43 based on information on the size of the sheet S from, for example, a sheet size detection sensor 111, a shift mechanism position detection sensor 31, and a shift motor 32 that adjusts the position of the shift mechanism 30 by moving it back and forth in the ±A direction.

[0025] The leading edge alignment mechanism 40 has an initial position of an alignment guide plate 41 determined according to the size of the sheet S, and the sheet S transported by the holding member 11 abuts against the alignment guide plate 41 arranged at the initial position and moves to the sheet tray 5 below where it is stacked as a stack of sheets. In this embodiment, the positioning of the leading edge aligning mechanism 40 is performed mainly by the shift motor 32 positioning the shift mechanism 30.

[0026] 4 is a control block diagram of the control unit 50 that controls the operation of the first sheet stacking device 170. The control unit 50, which is made up of a well-known microcomputer having a CPU, ROM, RAM, etc., receives input signals and input information from the sheet size detection sensor 111, the sheet leading edge detection sensor 8, and other sensors, and controls the operation of various actuators in the first sheet stacking device 170, such as the motor 14, the blower fan 15, etc. The control unit 50 has a tip alignment motor 45, which is a stepping motor that operates the tip alignment mechanism described later, a torque detection unit 51 that detects the torque of each motor with the shift motor 32, a position detection unit 52 for detecting the position of the tip alignment mechanism 40, and a guide drive unit 53 that controls the operation of the holding member 11. The control unit 50 also has a loading abnormality detection unit 54 which is a means for transmitting error information to notify the higher-level operation unit 190 of an abnormality when any of these units detects an abnormality. The control unit 50 may also have an encoder 55 as a step-out detection function for detecting step-out of the leading edge alignment motor 45 or the shift motor 32, as will be described later. In addition, such a control unit 50 may be provided, for example, in both the first sheet stacking device 170 and the second sheet stacking device 180. In that case, the functions already described are the same for the second sheet stacking device 180, so the description will be omitted.

[0027] The torque detector 51 monitors the torque values ​​of the leading edge alignment motor 45 and the shift motor 32 . The position detection unit 52 calculates the position of the partition member 42 based on signals from the leading edge alignment mechanism position detection sensor 44 and the shift mechanism position detection sensor 31, and controls the leading edge alignment mechanism 40 to be in an appropriate position. The guide driving unit 53 controls the operation of the guide mechanism 7 by rotating or stopping the holding member 11 . The loading abnormality detection unit 54 is a loading abnormality detection means for notifying an error to the operation unit 190, which is a higher-level device, of a sheet loading abnormality in the first sheet loading device 170 when an abnormality occurs in the operation of the torque detection unit 51, the position detection unit 52, the guide drive unit 53, etc.

[0028] Next, a sheet conveying process by the above-mentioned first sheet stacking device 170 will be described. In addition, since the stacking of sheets S in the first sheet stacking device 170 and the stacking of sheets S in the second sheet stacking device 180 can be performed with the same configuration and the same control, only the first sheet stacking device 170 will be described in this embodiment. First, the first sheet stacking device 170 acquires length information of the sheet S to be transported and stacked. Specifically, the size information based on the length and width of the sheet S detected by the sheet size detection sensor 111, or the size information of the sheet S input by the operator from the operation unit 190 of the image forming apparatus 1 is used. Based on the length information of the sheets S, in the first sheet stacking device 170, the leading edge aligning mechanism 40 moves in advance to an initial position that defines the length of the sheet tray 5 in the sheet conveying direction A. Next, when the sheet S on which an image is formed by driving the sheet feeder 110, the sheet position correction device 120, and the imaging device 130 is transported to the first sheet stacking device 170, the supply roller 171 starts transporting the sheet S sent after the image is formed by the imaging device 130, and the transport mechanism 6 is driven. At this time, the guide mechanism 7 is stopped in the standby state shown in FIG. 2 in which the holding member 11 is stopped at the standby position, and the blower fan 15 starts operating so as to always keep a constant air volume.

[0029] Thereafter, it is determined whether the sheet leading edge detection sensor 8 has detected the leading edge of the sheet S, and if it is determined that the leading edge has been detected, a first predetermined time is measured, which is the elapsed time based on the leading edge detection time of the sheet S. This first predetermined time is determined in advance according to the size of the sheet S to be conveyed. When the first predetermined time has elapsed, the conveyor belt 10 starts to run, and the holding member 11, which has been stopped at the standby position, starts to move in the sheet conveying direction A. At this time, since the conveying speed of the sheet S by the conveying mechanism 6 is faster than the moving speed of the holding member 11, the leading edge of the sheet S enters the holding member 11 from the opening 11a, and the leading edge that has entered is clamped and held by the clamping portion 11b.

[0030] The moving speed of the holding member 11, i.e., the driving speed of the motor 14 that drives the transport belt 10, is controlled by the control unit 50 so that the conveying speed of the sheet S by the conveying mechanism 6 and the moving speed of the holding member 11 are equal when the entry of the sheet S into the holding member 11 is completed. In this manner, the leading edge of the sheet S enters the inside of the holding member 11 due to the speed difference until the moving speed of the holding member 11 becomes equal to the conveying speed of the sheet S by the conveying mechanism 6. The time from when the holding member 11 starts moving to when the entry of the sheet S into the holding member 11 is completed is the second predetermined time. The amount of entry of the leading edge of the sheet S into the holding member 11 corresponding to the first and second predetermined times at this time is the predetermined amount C shown in FIG. 5.

[0031] When the holding member 11 holds the sheet S, that is, when the amount of penetration of the leading end of the sheet S into the holding member 11 reaches a predetermined amount C, a first acceleration is performed in the moving speed of the holding member 11, and a third predetermined time according to the size information of the sheet S obtained in advance is timed. Using the speed difference between the conveying speed of the sheet S by the conveying mechanism 6 and the moving speed of the holding member 11, which is generated by the first acceleration, the conveying movement of the sheet S by the conveying mechanism 6 and the guide mechanism 7 is started. At this time, the moving speed of the holding member 11 becomes faster than the conveying speed of the sheet S by the conveying mechanism 6, and the holding member 11 conveys the sheet S while pulling the leading end of the sheet S, so that it is possible to prevent the sheet S from being bent as compared with the case of a constant speed. During this conveyance, the force with which the holding member 11 holds the sheet S is smaller than the frictional force between the conveying mechanism 6 and the sheet S, so the sheet S gradually comes out of the holding member 11, but the state in which the sheet S is held by the holding member 11 is maintained from the position where the sheet S is held to the position where the sheet S is released.

[0032] When a third predetermined time has elapsed since the holding member 11 held the sheet S, a second acceleration is performed in the moving speed of the holding member 11, and the moving speed of the holding member 11 is further accelerated to separate the sheet S from the holding member 11. Even if the sheet S comes out of the conveying mechanism 6 before the sheet S is separated from the holding member 11, the sheet S is separated from the holding member 11 due to the inertial force of the sheet S. FIG. 6 shows the state when the sheet S is separated from the holding member 11. In FIG. 6, the symbol D indicates an acceleration position, which is the position of the holding member 11 where the second acceleration is performed, and the symbol E indicates a separation position, which is the position of the holding member 11 where the sheet S is separated. FIG. 7 shows a case where a small-sized sheet S1, which is smaller than the sheet S, is used instead of the sheet S. As shown in Figure 7, when a small-size sheet S1 is used, the control unit 50 adjusts the acceleration position D and separation position E of the small-size sheet S1, and further operates the shift mechanism 30 to move the position of the base portion 43 of the leading-edge alignment mechanism 40 in the -A direction, thereby changing the positions of the alignment guide plate 41 and the partition member 42 to positions that match the small-size sheet S1.

[0033] In this manner, the sheet S is separated from the holding member 11 due to the speed difference between the conveying speed of the sheet S by the conveying mechanism 6, which is generated by the second acceleration, and the moving speed of the holding member 11. The sheet S that has left the conveying mechanism 6 and is separated from the holding member 11 receives the wind force from the blower fan 15 and falls toward the sheet tray 5, and is stacked on the sheet tray 5. When the sheets S are stacked on the sheet tray 5, the leading edge alignment mechanism 40 is located downstream in the sheet conveying direction A, so that at least the sheets S are prevented from moving downstream beyond the surface of the partition member 42 of the leading edge alignment mechanism 40.

[0034] When the sheet S is released from the holding member 11, a fourth predetermined time according to the size information of the sheet S acquired in advance is counted, and when the fourth predetermined time has elapsed, the holding member 11 begins to decelerate and stops at the standby position.

[0035] Thereafter, it is determined whether the image forming operation in the image forming device 130 is completed or not, and if it is determined that the image forming operation is not completed, it is determined whether the sheet leading edge detection sensor 8 has detected the leading edge of the sheet S or not, and the above-mentioned operation is repeated until the image forming operation is completed. If it is determined that the image forming operation is completed, the operation of the conveying mechanism 6 and the blower fan 15 is stopped.

[0036] When the image forming operation by the imaging device 130 is completed and a predetermined number of sheets S are placed on the sheet tray 5 as a sheet stack, the first sheet stacking device 170 performs an operation of aligning the edges of the sheets S using the leading edge alignment mechanism 40. Note that, assuming a general case, leading edge alignment by the leading edge alignment mechanism 40 is performed after the image forming operation is completed, but it may be performed when an arbitrary number of sheets are placed on the sheet tray 5. Specifically, the leading edge alignment operation of the leading edge alignment mechanism 40 is performed by, after the sheet S is placed on the sheet tray 5, operating the leading edge alignment motor 45, causing the base portion 43, the alignment guide plate 41, and the partition member 42 to reciprocate in the ±A direction as shown in Figure 8. By this operation, the protruding ends of the stacked sheets S in the A direction are pressed against the alignment guide plate 41 so as to be in the same plane. The driving source for this pressure is the leading edge alignment motor 45 .

[0037] Generally, in conjunction with the leading edge alignment operation, a left-right alignment operation is also performed in the sheet width direction B by the side alignment mechanism 60. As shown in FIG. 9, a total of four side alignment mechanisms 60 are provided, two on each side, so as to surround both sides of the sheets S placed on the sheet tray 5. The side alignment mechanism 60 has a side alignment plate 61 arranged parallel to the side of the sheet S, a rod-shaped shaft portion 62 supporting the side alignment plate 61, and a side alignment motor 63 that reciprocates the shaft portion 62 in the direction B in the figure. The control unit 50 controls the side alignment motor 63 to operate the opposing side alignment plates 61 to sandwich the sheets S placed on the sheet tray 5, thereby performing a left-right alignment operation to align the position of the sheets S in the width direction.

[0038] As a comparative example of the present invention, a configuration in which a leading edge aligning mechanism 70 is provided similarly to the present invention will now be described with reference to FIG. The leading edge aligning mechanism 70 has the same basic configuration as the leading edge aligning mechanism 40 already described, but differs in that it does not have the partition member 42 protruding upward from the base portion 43. When the sheet S held by the holding member 11 moves from the standby position, accelerates at the acceleration position D, and then reaches the release position E, the sheet S releases from the holding member 11 and falls freely onto the sheet tray 5. At this time, an air flow may be generated by the blower fan 15 so as to press the sheet S downward, but since there is little effect on whether or not the sheet S is pressed downward in this configuration, a description thereof will be omitted.

[0039] Here, if for some reason, such as the clamping portion 11b of the holding member 11 clamping the sheet S more tightly than expected, the sheet S does not come off the holding member 11 at the release position, the sheet S may move together with the holding member 11 by the conveying belt 10, as shown in Figure 11, and may pass the drive roller 12 and be pulled downstream in the sheet conveying direction A. When the sheet S is pulled in downstream in the sheet transport direction A in this manner, this is referred to as the sheet flowing in, and in the first sheet stacking device 170, the tip of the sheet stacking position when, for example, the length of the sheet that can be handled is at its maximum is referred to as the sheet stacking limit position M. 11, if the sheet S goes downstream of the sheet stacking limit position M, the sheet S goes to a position that is not normally expected, and there is a high probability that a jam will occur. In addition, since the sheet S moves to a position that is not normally expected in normal use, it becomes difficult to manually remove the sheet S to clear the jam. Therefore, in an embodiment of the present invention, in order to prevent such sheets S from heading downstream of the sheet stacking position, the leading edge alignment mechanism 40 is provided with a partition member 42 that prevents the sheets S from passing downstream of the leading edge alignment mechanism 40.

[0040] This configuration will now be described in more detail. In this embodiment, as seen from the downstream side in the transport direction, a plurality of transport belts 10 and holding members 11 are provided in the width direction as shown in FIG. When viewed from the downstream side in the conveying direction, the partition member 42 is provided in such a manner that the portion through which the conveyor belt 10 and the holding member 11 pass is opened in a concave shape. In other words, the leading edge alignment mechanism 40 has the partition member 42 that extends onto the movement path of the holding member 11 and the open recess 42a opened in the partition member 42, and is disposed so as not to impede the movement of the holding member 11 and to impede the extension of the conveying path of the sheet S. Here, the phrase "on the extension of the conveying path of the sheet S" is used to express that the sheet S ideally separates from the holding member 11 at the release position E, and when this ideal behavior is being performed, the sheet S does not collide with the partition member 42, and therefore is not on the (normal) conveying path of the sheet S.

[0041] As already mentioned, the partition member 42 is formed in the leading edge alignment mechanism 40 that aligns the leading edge position by contacting the leading edge of the sheets S facing the conveying direction, so the position of the partition member 42 is downstream in the conveying direction from the leading edge position F of the sheet stack loaded on the sheet tray 5. This position can vary depending on the wind or conveying force, but it can be said to be approximately near the separation position E shown in FIG. According to this configuration, as shown in FIG. 13, even if the force with which the holding member 11 clamps the sheet S is strong and the leading edge of the sheet S does not separate from the clamping portion 11b even after passing the separation position E, one side of the sheet S on the downstream side in the conveying direction will abut against the partition member 42, preventing the sheet S from proceeding downstream of the sheet stacking position. On the other hand, the holding member 11 passes through the open recess 42a formed in the partition member 42, and therefore can move without being hindered from being moved by the conveyor belt 10.

[0042] Since such a holding member 11 has an opening recess 42a through which the sheet S can pass without contact, the sheet S does not go downstream in the sheet conveying direction A from the leading edge position F, so that the sheet can be prevented from flowing downstream in the conveying direction from the sheet stacking position.

[0043] Problems with the above-mentioned configuration will also be explained below. By providing the partition member 42 in this manner, even if the sheet S does not separate at the separation position E, the sheet S will collide with the partition member 42 at the leading end position F. At this time, as shown in FIG. 13, there is a possibility that the following holding member 11 may collide with the sheet S. Although the partition member 42 is supported by the base portion 43, the impact of the collision of the sheet S may cause deformation of the partition member 42 or a high load on the leading edge alignment motor 45, resulting in loss of synchronization.

[0044] In this embodiment, therefore, in order to prevent damage or overload to each part of the leading edge alignment mechanism 40, including the partition member 42, in the event of such a collision, the step-out load of the leading edge alignment motor 45 is designed to be smaller than the deformation resistance load of each of the alignment guide plate 41, the partition member 42, and the holding member 11.

[0045] By adjusting the step-out load of the leading edge alignment motor 45 in this manner, the leading edge alignment motor 45 will step out before any of the alignment guide plate 41, the partition member 42, or the holding member 11 is deformed due to a collision. When step-out occurs due to such an impact, the partition member 42 moves downstream in the sheet conveying direction A. In this manner, the partition member 42 retreats rearward due to step-out.

[0046] Furthermore, when the torque detector 51 detects an abnormal torque of the leading end alignment motor 45, the controller 50 stops driving the guide mechanism 7 using the guide driver 53. Since the torque detection unit 51 monitors the motor torque of the leading edge alignment motor 45, for example, when the leading edge alignment motor 45 performs the leading edge alignment operation when the sheets S are actually jammed, a heavy load is applied to the leading edge alignment motor 45 due to the jamming of the sheets S. Therefore, by monitoring the torque of the leading edge alignment motor 45, the control unit 50 uses the guide drive unit 53 to stop the operation of the guide mechanism 7 when a stacking abnormality occurs in the sheets S. At the same time, the stacking abnormality detection unit 54 notifies the operation unit 190 that an abnormality has occurred in the first sheet stacking device 170 .

[0047] According to this configuration, even if the sheet S gets caught on the holding member 11 and causes a jam, the control unit 50 can detect this and stop the operation of the guide mechanism 7, so that the sheet S can be prevented from moving further back than the sheet conveying direction A. This makes it easy for the operator to deal with the abnormality, such as by removing the sheet S. Although the detection of torque abnormality of the leading edge alignment motor 45 has been described here, the same thing may be done by monitoring torque abnormality of the shift motor 32. In that case, early detection of jamming of the sheet S is also possible.

[0048] Furthermore, when a jam is detected in the first sheet stacking device 170, the loading abnormality detection unit 54 notifies the operation unit 190 that an abnormality has occurred, and the operation unit 190, upon receiving such notification, can stop the use of the conveying means located upstream of the first sheet stacking device 170 in the conveying direction. An example of such control includes stopping the image formation operation of the image forming device 130. Therefore, the loading abnormality detection unit 54 operates as a loading abnormality detection unit that detects an abnormality that occurs when the sheets S are stacked in the first sheet stacking device 170 or the second sheet stacking device 180.

[0049] Alternatively, when the loading abnormality detection unit 54 detects an abnormality, for example, a second sheet stacking device 180 that is arranged downstream in the conveying direction from the first sheet stacking device 170 in which the abnormality has occurred may be used, and the sheet S may be conveyed to the second sheet stacking device 180 using the bypass conveying path 9. With this configuration, by having multiple sheet stacking devices (first sheet stacking device 170, second sheet stacking device 180) as destinations for sheets S, even when it is difficult for the first sheet stacking device 170 to stack sheets S, the second sheet stacking device 180 can continue the stacking operation, so that even if a malfunction occurs, the operating time of the entire image forming apparatus 1 is not reduced. Furthermore, when the operation unit 190 receives such a notice of an abnormality, the operator may be notified of the occurrence of the abnormality by any notification means such as an alarm sound or lighting up the screen.

[0050] Now, as already mentioned, if the step-out load of the leading edge alignment motor 45 is adjusted, the leading edge alignment motor 45 will step out before any of the alignment guide plate 41, the partition member 42, or the holding member 11 is deformed due to a collision. As another embodiment of the present invention, in addition to detecting an abnormal torque, for example, a method of detecting whether or not such a step-out has occurred may be considered.

[0051] A schematic diagram of when such a step-out occurs is shown in Fig. 14. In Fig. 14, when sheet S collides with partition member 42 and step-out occurs, partition member 42 and alignment guide plate 41 move backward as a whole in the downstream direction A from reference position G due to the step-out. In other words, as shown by the solid line in Fig. 14, partition member 42 moves backward due to the step-out, and moves to the retracted position due to the force of the collision with sheet S. In this case, for example, one method for detecting step-out of the leading edge alignment motor 45, when the leading edge alignment motor 45 is a stepping motor, is to monitor the rotation angle of the motor by a known method using the encoder 55 or the like, and detect any deviation from the ideal control value. According to this method, even if the leading edge alignment motor 45 deviates from the ideal control value by, for example, 1 mm, it can be detected as a loss of synchronization, so that stacking abnormality of the sheets S can be detected quickly and accurately.

[0052] The out-of-step detection function using the encoder 55 may be provided in the shift motor 32. As to whether these out-of-step detection functions should be provided to the shift motor 32 or the leading edge alignment motor 45, it is effective to provide them to the motor with the smaller out-of-step load.

[0053] When the control unit 50 detects out-of-step of the leading edge alignment motor 45 or the shift motor 32 using the out-of-step detection function of the encoder 55 or the like, it notifies the operation unit 190 of the abnormality of the first sheet stacking device 170 using the loading abnormality detection unit 54. Other operations when an abnormality is detected are the same as those when an abnormality is detected using the torque detection unit 51, and therefore a description thereof will be omitted.

[0054] Although providing such a step-out detection function makes it possible to detect abnormalities in the stacking of the sheets S at high speed and with high accuracy, in actual operation, there may be many cases where such high accuracy is not necessary. For example, even if the sheet S cannot be released at the release position E, collides with the partition member 42, and is piled up on the sheet tray 5, the leading ends may be aligned to the extent that they can be handled as a sheet stack without any problems by the leading end alignment operation of the leading end alignment mechanism 40.

[0055] In a method of monitoring the leading edge alignment motor 45 or the shift motor 32 using a step-out detection function of an encoder or the like, a loading abnormality may be detected as a step-out even when such a step-out does not cause a problem in actual operation.

[0056] Therefore, as shown in FIG. 15(a), a moving distance detection protrusion 46 may be provided on the base portion 43 in place of an out-of-step detection function such as an encoder. The function of the movement distance detection protrusion 46 will now be described. The movement distance detection protrusion 46 is provided below the base portion 43 and downstream of the partition member 42 in the sheet conveying direction A, and is formed as a protrusion that protrudes downward. If the impact caused by the collision of the sheet S is large, the out-of-step distance becomes longer, and for example, the movement distance detection protrusion 46 moves further rearward from the reference position G, and the leading edge alignment mechanism position detection sensor 44 out-of-steps to a position where the movement distance detection protrusion 46 can be measured, as shown in Figure 15(b). At this time, since the tip alignment mechanism position detection sensor 44 can detect the movement distance detection protrusion 46, if the position change at the time of the collision occurs and the movement distance caused by the step-out exceeds a predetermined distance, i.e., the fixed distance L from the position of the tip alignment mechanism position detection sensor 44 at the reference position G to the movement distance detection protrusion 46, it becomes possible to detect that the tip position has become an abnormal position. By using the tip alignment mechanism position detection sensor 44 as a position detection sensor in this way, it is possible to detect a step-out of a fixed distance or more by detecting the movement distance detection protrusion 46 without requiring additional costs. Alternatively, a known position detection sensor may be provided specifically for detecting the movement distance detection convex portion 46. Such a position detection sensor may be, for example, an infrared sensor that is placed sideways and has a light beam blocked by the convex portion of the movement distance detection convex portion 46.

[0057] In this way, by providing the movement distance detection convex portion 46 on the base portion 43, if the movement distance of the movement distance detection convex portion 46 exceeds a certain distance, this can be detected as an abnormality by an existing position sensor, without the need to introduce an expensive mechanism such as an encoder. According to this configuration, only when the degree of out-of-step is severe, a sheet stacking abnormality is detected, so that only out-of-step of a predetermined distance or more can be detected as an abnormality inexpensively without taking minor stacking abnormalities that do not cause problems in practical operation into consideration. Also, according to this configuration, the moving distance detection protrusion 46 operates as a moving distance detection function that detects when the retreat due to out-of-step reaches a certain distance L or more.

[0058] Naturally, such a moving distance detection convex portion 46 may be provided on the shift mechanism 30 as shown in Fig. 16. Here, Fig. 16(a) and Fig. 16(b) show the case of a small size sheet S1 in which the length of the sheet S is different. Furthermore, in this configuration, by making the step-out load of the shift motor 32 lower than the step-out load of the leading edge alignment motor 45, the shift mechanism 30 is preferably moved backward first due to step-out.

[0059] According to this configuration, when shift mechanism 30 loses step-out by a certain distance L or more as shown in FIG. 16(b), movement distance detection convex portion 46 is detected by shift mechanism position detection sensor 31 provided in shift mechanism 30. On the other hand, in such a mechanism, the movement distance for detection with respect to the reference position G may increase or decrease depending on the length of the sheet S, for example, when a small size sheet S1 is used. However, even in a case such as that shown in Figure 16(b) where the out-of-step distance is not detected until it reaches its maximum, the small-size sheet S1 will not go behind the partition member 42, so that the sheet can be prevented from flowing downstream in the sheet conveying direction A. Also, even in the case shown in Figure 16 (b), the partition member 42 will not be lowered further back than the sheet stacking limit position M shown in Figure 11, so as long as it does not go further back than the partition member 42, even if the small size sheet S1 is not stacked correctly, it can be easily removed manually.

[0060] In the above embodiment, an example was shown in which an inkjet recording device that forms a full-color image was used as the image forming apparatus 1 to which the present invention can be applied, but the image forming apparatus to which the present invention can be applied is not limited to this, and the present invention can also be applied to copying machines, facsimiles, multi-function machines, etc. In the above embodiment, a configuration is shown in which a sheet S is used as the recording medium on which an image is formed, but this sheet S is not limited to recording paper, but also includes cardboard, postcards, roll paper, envelopes, plain paper, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, OHP film, resin films, etc., and any material that is in sheet form, capable of forming an image, and has hygroscopic properties may be used.

[0061] For example, aspects of the present invention are as follows. [1] The sheet stacking device comprises a sheet tray 5 on which a stack of sheets is loaded, a transport mechanism 6 which transports sheets S in a transport direction A toward the sheet tray 5, and a holding member 11 which holds the leading edge of the sheets S transported by the transport mechanism 6 at a standby position and then moves in the transport direction A of the sheets S to guide the transport of the sheets S, and which uses the speed difference between the sheet transport speed of the transport mechanism and the moving speed of the guide member to detach the leading edge of the sheets held by the guide member from the guide member at a detachment position and drop the detached sheets onto the loading table for loading, and has a leading edge alignment mechanism for aligning the leading edge position of the sheets on the loading table in the transport direction, and the leading edge alignment mechanism has a partition member extending onto the movement path of the guide member. According to this configuration, it is possible to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position.

[0062] [2] In addition to the configuration described in [1], the leading edge alignment mechanism has a leading edge alignment motor 45, and the step-out load of the leading edge alignment motor 45 is designed to be smaller than the deformation resistance load of the leading edge alignment mechanism and the holding member 11. According to this configuration, when a jam occurs in the sheet S, the leading edge alignment motor 45 first goes out of step and the partition member 42 retreats, thereby preventing deformation of the holding member 11 and the partition member 42 and preventing the sheet from flowing downstream in the conveying direction from the partition member 42.

[0063] [3] In addition to the configuration described in [1] or [2], the control unit 50 has a torque detection unit 51 as a torque abnormality detection function, and when a torque abnormality of the tip alignment motor 45 is detected during operation of the tip alignment mechanism 40, the control unit 50 stops driving the holding member 11. According to this configuration, by detecting a torque abnormality in the leading edge alignment motor 45, the drive of the holding member 11 can be stopped immediately when such an abnormality occurs, thereby preventing the sheet from flowing downstream in the conveying direction beyond the partition member 42.

[0064] [4] In addition to the configuration described in any one of [1] to [3], the first sheet stacking device 170 has a leading edge alignment mechanism position detection sensor 44 that detects the position of the leading edge alignment mechanism 40, and when it detects that the position of the leading edge alignment mechanism 40 has moved a certain distance L or more from the reference position G due to loss of synchronization, the driving of the holding member 11 is stopped. With this configuration, it is possible to prevent the sheet from flowing downstream in the transport direction from the partition member 42, and the position change that occurs during a collision can be detected by the leading edge alignment mechanism position detection sensor 44, which detects the position of the leading edge alignment motor 45. Therefore, when such an abnormality occurs, the drive of the holding member 11 can be stopped quickly to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position.

[0065] [5] In addition to the configuration described in any one of [1] to [4], an encoder 55 is provided as a step-out detection function for the leading edge alignment motor 45, and when the step-out detection function detects the retreat of the partition member 42, the drive of the holding member 11 is stopped. According to this configuration, it is possible to prevent the sheet from flowing downstream in the transport direction from the partition member 42, and the encoder 55 can detect the change in position of the partition member 42 that occurs when the sheet S collides with it. Therefore, when such an abnormality occurs, the drive of the holding member 11 can be stopped quickly to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position.

[0066] [6] In addition to the configuration described in any one of [1] to [5], the apparatus has a shift mechanism 30 that moves the leading edge alignment mechanism 40 in the conveying direction, and a shift motor 32 that moves the shift mechanism 30, and the step-out load of the shift motor is designed to be smaller than the deformation resistance load of the leading edge alignment mechanism 40 and the holding member 11. According to this configuration, when a jam occurs with the sheet S, the shift motor first goes out of step and the partition member 42 retreats, thereby preventing deformation of the holding member 11 and the partition member 42 and preventing the sheet from flowing downstream in the conveying direction from the partition member 42.

[0067] [7] In addition to the configuration described in any one of [1] to [6], the device has a torque detection unit 51 equipped with a torque abnormality detection function, and when a torque abnormality of the shift motor 32 is detected, the control unit 50 stops driving the retaining member 11. According to this configuration, when a torque abnormality occurs, the driving of the holding member 11 is stopped immediately, and it is possible to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position.

[0068] [8] In addition to the configuration described in any one of [1] to [7], the first sheet stacking device 170 has a shift mechanism position detection sensor 31, and when it detects that the position of the shift mechanism 30 has moved a certain distance L or more from the reference position G due to loss of synchronization, it stops driving the holding member 11. With this configuration, it is possible to prevent sheets from flowing downstream in the transport direction from the partition member 42, and the shift mechanism position detection sensor 31, which detects the position of the shift mechanism 30, can detect the position change that occurs during a collision. Therefore, when such an abnormality occurs, the drive of the holding member 11 can be stopped quickly, thereby preventing sheets from flowing downstream in the transport direction from the sheet stacking position.

[0069] [9] In addition to the configuration described in any one of [1] to [8], the first sheet stacking device 170 has an encoder 55 as a function of detecting out-of-step of the shift motor 32, and when the out-of-step detection function detects the backward movement of the shift mechanism 30, the drive of the holding member 11 is stopped. According to this configuration, it is possible to prevent the sheet from flowing downstream in the transport direction from the partition member 42, and the encoder 55 can detect the change in position of the partition member 42 that occurs when the sheet S collides with it. Therefore, when such an abnormality occurs, the drive of the holding member 11 can be stopped quickly to prevent the sheet from flowing downstream in the transport direction from the sheet stacking position.

[0070]

[10] The image forming apparatus 1 further includes a first sheet stacking device 170 having the configuration described in any one of [1] to [9], and a stacking abnormality detection unit 54 that detects the stop of the holding member 11 as an abnormality. According to this configuration, the loading abnormality detection unit 54 can notify the operation unit 190 of a loading abnormality, so that the driving of the holding member 11 can be stopped quickly and the flow of the sheet downstream in the conveying direction from the sheet loading position can be prevented.

[0071]

[11] In addition to the configuration described in

[10] , the image forming apparatus 1 has transport means such as a sheet feeding device 110 that transports the sheet S to the first sheet stacking device 170, a sheet position correction device 120, an image forming device 130, a sheet drying device 140, a sheet cooling device 150, and a sheet inverting device 160, and when the loading abnormality detection unit 54 detects an abnormality, the transport of any of these devices located upstream of the first sheet stacking device 170 in the transport direction is stopped. According to this configuration, when the loading abnormality detection unit 54 detects a loading abnormality, the conveying operation of the image forming apparatus 1 can be stopped immediately.

[0072]

[12] In addition to the configuration described in

[10] or

[11] , the image forming apparatus 1 is provided with a second sheet stacking device 180 different from the first sheet stacking device 170, and when the stacking abnormality detection unit 54 detects an abnormality, the sheet S is transported to the second sheet stacking device 180. With this configuration, by having multiple sheet stacking devices (first sheet stacking device 170, second sheet stacking device 180) as destinations for sheets S, even when it is difficult for the first sheet stacking device 170 to stack sheets S, the second sheet stacking device 180 can continue the stacking operation, so that even if a malfunction occurs, the operating time of the entire image forming apparatus 1 is not reduced.

[0073]

[13] In addition to the configuration described in any one of

[10] to

[12] , the image forming apparatus 1 has a notification means for notifying an operator of an abnormality, and when the loading abnormality detection unit 54 detects an abnormality, the notification means notifies the operator of the abnormality. With this configuration, the operator can be notified of the abnormality immediately.

[0074]

[14] The image forming apparatus 1 also includes a first sheet stacking device 170 having the configuration described in any one of [1] to [9]. According to this configuration, in the image forming apparatus 1, the first sheet stacking device 170 can stack the sheets S.

[0075] Although a preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely examples of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Explanation of symbols]

[0076] 1. Image forming device 5 Sheet tray (loading platform) 6. Conveyor mechanism 8 Sheet leading edge detection sensor 11 Holding member (guide member) 30 Shift mechanism 31 Shift mechanism position detection sensor (position detection sensor) 32 Shift motor 40 Tip alignment mechanism 42 Partition material 45 Tip-matching motor 44 Tip alignment mechanism position detection sensor (position detection sensor) 50 Control section 51 Torque detection section (torque abnormality detection function) 52 Position detection unit 53 Guide drive unit 54 Loading abnormality detection unit (loading abnormality detection means) 55 Encoder (step-out detection function) 170 First sheet loading device (sheet loading device) 180 Second sheet loading device (sheet loading device) A Conveying direction B Sheet width direction C. Sheet tip penetration D Acceleration position E Detachment position F Seat tip position G Reference position S Seat S1 Small size sheet [Prior art documents] [Patent documents]

[0077] [Patent Document 1] JP 2015-151216 A [Patent Document 2] JP 2023-065102 A [Patent Document 3] Patent Publication No. 2021-147232 [Patent Document 4] Patent No. 4891385

Claims

1. a loading platform on which a sheet stack is loaded; a conveying mechanism that conveys the sheet in a conveying direction toward the stacking table; a guide member that holds a leading end of the sheet conveyed by the conveying mechanism at a standby position and then moves in the conveying direction of the sheet to guide conveyance of the sheet; Equipped with a sheet stacking device that uses a speed difference between a sheet conveying speed of the conveying mechanism and a moving speed of the guide member to separate a leading end of the sheet held by the guide member from the guide member at a separation position, and drops the separated sheet onto the stacking table and stacks the sheet, a leading edge alignment mechanism for aligning a leading edge position of the sheet on the stacking table in the conveying direction; 4. The sheet stacking device according to claim 1, wherein the leading edge aligning mechanism has a partition member extending onto a moving path of the guide member.

2. 2. The sheet stacking device according to claim 1, the leading edge alignment mechanism has a leading edge alignment motor that moves the partition member to a predetermined position and holds it there; 4. The sheet stacking device according to claim 1, wherein a step-out load of said leading edge aligning motor is designed to be smaller than a deformation resistance load of said leading edge aligning mechanism and said guide member.

3. 3. The sheet stacking device according to claim 2, A sheet stacking device having a control unit with a torque abnormality detection function, and when the leading edge alignment motor detects a torque abnormality during operation of the leading edge alignment mechanism, the control unit stops driving the guide member.

4. 3. The sheet stacking device according to claim 2, a position detection sensor for detecting a position of the leading end alignment mechanism; 4. A sheet stacking device comprising: a sheet aligning mechanism for aligning a sheet on a sheet conveying member; a guide member for aligning a sheet on a sheet conveying member;

5. 3. The sheet stacking device according to claim 2, A function for detecting out-of-step of the leading edge alignment motor is provided, a step-out detection function that detects the retreat of the partition member and stops driving the guide member.

6. 2. The sheet stacking device according to claim 1, a shift mechanism that moves the leading edge alignment mechanism in the transport direction; and a shift motor that moves the shift mechanism, The sheet stacking device according to claim 1, wherein a step-out load of said shift motor is designed to be smaller than a deformation resistance load of said leading edge aligning mechanism and said guide member.

7. 7. The sheet stacking device according to claim 6, A control unit having a torque abnormality detection function is provided.

4. The sheet stacking device according to claim 1, wherein the control unit stops driving the guide member when the shift motor detects a torque abnormality.

8. 7. The sheet stacking device according to claim 6, A position detection sensor that detects a position of the shift mechanism, 2. A sheet stacking device comprising: a shift mechanism for shifting a position of the sheet stacking member from a predetermined position by a distance greater than a predetermined distance;

9. 7. The sheet stacking device according to claim 6, The shift motor has a step-out detection function, a step-out detection function that detects a retreat of the shift mechanism and stops driving the guide member.

10. A sheet stacking device according to any one of claims 1 to 9; a loading abnormality detection means for detecting a stop of the guide member as an abnormality; An image forming apparatus comprising:

11. 11. The image forming apparatus according to claim 10, a conveying means for conveying the sheet to the sheet stacking device, When the stacking abnormality detection means detects the abnormality, the image forming apparatus stops the conveying means located upstream of the sheet stacking device in the conveying direction.

12. 11. The image forming apparatus according to claim 10, a plurality of sheet discharge destinations different from the sheet stacking device; When the stacking abnormality detection means detects the abnormality, the image forming apparatus conveys the sheet to any one of the sheet discharge destinations.

13. 11. The image forming apparatus according to claim 10, A notification means for notifying an operator of an abnormality is provided, When the abnormality detection means detects the abnormality, the notification means notifies the operator of the abnormality.

14. 10. An image forming apparatus comprising the sheet stacking device according to claim 1.

Images