Sheet stacking apparatus and image forming apparatus

Abstract

To provide a sheet stacking device capable of placing a marker on a sheet bundle without being affected by a fan.SOLUTION: The sheet loading device includes a loading member 14 and a conveying member 15, and further includes a marking device 41 for ejecting and placing a marker 34 on the upper surface of the uppermost transfer sheet S loaded on the loading member 14 for every arbitrary number of loaded sheets. A marking device 41 includes a marker storage part 35 having a discharge port 35a for discharging a marker 34 and storing the marker 34, a marker conveyance part 36 for conveying the marker 34 to discharge the marker 34 from the discharge port 35a, and a guide member 42 for guiding the marker 34 discharged from the discharge port 35a to prevent the marker 34 from moving in a direction opposite to a sheet conveyance direction.SELECTED DRAWING: Figure 12

Description

[Technical Field]

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

[0002] In an image forming apparatus that forms an image on a transfer sheet, a sheet stacking device is known that moves a guide member that transports the transfer sheet while holding the leading edge of the transfer sheet that is transported after image formation at the same speed as the sheet transport speed, and sends out the trailing edge of the transfer sheet with a transport member to transport and stack the transfer sheet on a stacking member (see, for example, Patent Document 1). Also known is a marking device that cuts a thin sheet-like or roll-like marker to a predetermined length and inserts it so that it protrudes from the sheet stack after each desired number of sheets to set specific divisions in the sheet stack (see, for example, Patent Document 2 and Patent Document 3).

[0003] When the marking device is applied to the sheet stacking device, the marker cut from the roll and placed on the sheet stack is subjected to a wind (called a fan wind) similar to that blown when the subsequent transfer sheet is placed on top of it. If the cut marker is blown outside the sheet stack by this fan wind, it may not function as a separator. Therefore, a technique is known in which the marker is not cut immediately after the transfer sheet is transported, but is cut after the subsequent transfer sheet has been completely placed on the sheet stack, thereby keeping the marker integrated with the roll until the subsequent transfer sheet has been completely placed, thereby preventing it from being blown away by a fan. Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned technology, the injection height of the marker supplied onto the sheet stack needs to be set so that the marker is positioned directly above the top sheet of the sheet stack. If the marker injection height is different from the height of the sheet stack (sheet stacking height), the following problems will occur. First, when a subsequent transfer sheet is placed on the marker, the end of the marker on the roll side floats. If this condition continues, there is a risk that the sheet stack height will be erroneously detected, resulting in transfer sheet transport and stacking problems. Second, the end of the marker after cutting may lean against the marking device, blocking the marker discharge port of the marking device and causing marker injection problems. Third, if the marker leans, it may not be inserted deep enough into the sheet stack, preventing it from reaching small-sized transfer sheets.

[0005] Furthermore, even if the marker ejection height is set directly above the sheet stacking height, if the stacking member is a liftable member, there is a risk that the stacking member may come into contact with the marking device if it is raised even slightly too high. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a sheet stacking device that is not affected by the wind from a fan and that can place a marker on a sheet stack. [Means for solving the problem]

[0006] The invention described in claim 1 is a sheet stacking device comprising a stacking member on which transfer sheets are stacked and a transport member that transports the transfer sheets in a sheet transport direction toward the stacking member, and a marking device that ejects and places a marker on the top surface of the top sheet, which is the top transfer sheet stacked on the stacking member, for every arbitrary number of sheets stacked, and is characterized in that the marking device has an outlet for discharging the marker, a marker storage unit for storing the marker, a marker transport unit for transporting the marker to discharge it from the outlet, and a guide member that guides the marker discharged from the outlet to prevent it from moving in the opposite direction to the sheet transport direction. [Effects of the Invention]

[0007] According to the present invention, the markers are guided by a guide member arranged in the direction of the fan's wind, thereby preventing the markers from falling off the top transfer sheet, and providing a sheet stacking device that can place markers on a stack of sheets without being affected by the fan's wind. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic front view of an image forming apparatus to which an embodiment of the present invention can be applied; [Figure 2] FIG. 2 is a schematic front view showing the sheet stacking device in which the holding member is in a standby position. [Figure 3] 10 is a schematic plan view showing the sheet stacking device in which the holding member is in a standby position; [Figure 4] FIG. 2 is a schematic view of a lifting device used in the sheet stacking device. [Figure 5] 10 is a schematic front view of the sheet stacking device showing a state in which the leading edge of the transfer sheet has entered the holding member by a predetermined amount. FIG. [Figure 6] 10 is a schematic front view of the sheet stacking device showing a state in which the transfer sheet has been released from the holding member. FIG. [Figure 7] 10 is a schematic front view of the sheet stacking device showing a state in which the small-sized transfer sheet has been released from the holding member. FIG. [Figure 8] FIG. 2 is a schematic side view of a sheet stacking device equipped with a marking device. [Figure 9] FIG. 2 is a schematic front view of a sheet stacking device equipped with a marking device. [Figure 10] FIG. 2 is a schematic diagram illustrating a marking device. [Figure 11] 10A and 10B are schematic diagrams illustrating problems with a sheet stacking device equipped with a marking device. [Figure 12] 1 is a schematic diagram illustrating a marking device according to a first embodiment of the present invention. [Figure 13] 1 is a schematic view showing a marking device and a sheet stacking device according to a first embodiment of the present invention. [Figure 14] FIG. 6 is a schematic diagram illustrating a marking device according to a second embodiment of the present invention. [Figure 15] FIG. 10 is a schematic diagram illustrating a marking device according to a third embodiment of the present invention. [Figure 16] FIG. 10 is a schematic diagram illustrating a marking device according to a fourth embodiment of the present invention. [Figure 17] FIG. 10 is a schematic view illustrating a marking device according to a fifth embodiment of the present invention. [Figure 18] 10A and 10B are schematic diagrams illustrating the behavior of the marker when the guide member and the second guide member are moved up and down in the third embodiment of the present invention. [Figure 19] 13A to 13C are schematic diagrams illustrating the behavior of the marker when the guide member and the second guide member are moved up and down in the fifth embodiment of the present invention. [Figure 20] FIG. 10 is a schematic diagram illustrating a marking device according to a sixth embodiment of the present invention. [Figure 21] 13 is a flowchart illustrating a series of operations of a sheet stacking device according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 shows an image forming apparatus to which one embodiment of the present invention can be applied. In the figure, the image forming apparatus 1 has a sheet feeding device 2 that stores transfer sheets S, which are recording media, a sheet position correction device 3 that corrects the position of the transfer sheets S, and an image creating device 4 that forms an image on the transfer sheets S. The image forming apparatus 1 further includes a sheet drying device 5 for drying the formed image, a sheet cooling device 6 for cooling the transfer sheet S, a sheet inverting device 7 for inverting the transfer sheet S, a first sheet stacking device 8 and a second sheet stacking device 9 for stacking the transfer sheet S as the sheet stacking device of the present invention, and an operation unit 10 for controlling each of the above-mentioned parts based on user instructions.

[0010] The sheet feeding device 2 and the sheet position correction device 3 are devices that convey the transfer sheets S that have been loaded and stored in advance one by one, and the sheet feeding device 2 is provided with a sheet size detection sensor 11 that detects the size of the transfer sheet S being fed. A plurality of sheet size detection sensors 11 are provided to detect the length and width of the transfer sheet S. The sheet position correction device 3 adjusts the timing of conveying the transfer sheet S based on the sheet size information sent from the sheet size detection sensor 11 so that the image forming device 4 forms an image at a predetermined position on the transfer sheet S.

[0011] In this embodiment, the image forming device 4 is an inkjet recording device that ejects ink of each color, black (K), cyan (C), magenta (M), and yellow (Y), to form a full-color image on the transfer sheet S. The image forming device 4 has liquid ejection devices 13K, 13C, 13M, and 13Y that eject the above-mentioned color inks arranged around the main drum roll 12, and forms inkjet images of each color on the transfer sheet S. The sheet drying device 5 and the sheet cooling device 6 dry the inkjet image formed on the transfer sheet S and then cool it, thereby allowing the inkjet image to be stably maintained on the transfer sheet S.

[0012] If necessary, the sheet inverting device 7 inverts the transfer sheet S using a switchback method and re-transports it to the sheet position correction device 3, switching the image forming surface of the transfer sheet S, i.e., the surface facing the drum roll 12. Each of the above-mentioned components is appropriately controlled in response to user operations via the operating unit 10, and an inkjet image is formed on the transfer sheet S. In this embodiment, an inkjet printer that forms inkjet images has been described as the image forming apparatus 1, but the image forming apparatus is not limited to this and may be an image forming apparatus having an electrophotographic image forming unit as the image creating device 4. In this case, a fixing device that fixes the toner image onto the transfer sheet S may be provided in place of the sheet drying device 5 and the sheet cooling device 6. The configuration of each part within such an image forming apparatus 1 may be the same as that of a conventional image forming apparatus, and detailed description of each part will be omitted.

[0013] Next, we will explain the first sheet stacking device 8, which is a sheet stacking device of the present invention. The first sheet stacking device 8 and the second sheet stacking device 9 are both discharge destinations of the transfer sheet S in the image forming apparatus 1, and may have the same configuration or different configurations. In this embodiment, the first sheet stacking device 8 and the second sheet stacking device 9 have the same configuration, and only the sheet discharge destinations are different. 2 has a sheet tray 14 as a stacking member, a sheet transport mechanism 15 as a transport member that transports the transfer sheet S to the sheet tray 14, and a guide mechanism 16 that grips the leading edge of the transfer sheet S transported toward the sheet tray 14 and transports it downstream in the transport direction. The first sheet stacking device 8 also has a sheet leading edge detection sensor 17 that detects the leading edge of the transfer sheet S on the upstream side of the sheet transport mechanism 15 in the sheet transport direction, and a detour transport path 18 that transports the transported transfer sheet S by bypassing the sheet tray 14 to a second sheet stacking device 9 located downstream of the first sheet stacking device 8 in the sheet transport direction.

[0014] The sheet tray 14 on which the transfer sheets S after image formation are stacked is initially positioned below the transfer sheets S fed by the sheet transport mechanism 15, and moves downward as the transfer sheets S are stacked on the sheet tray 14, so that the position of the top surface of the stacked sheet stack is maintained at a height that makes it easy to stack the transfer sheets S discharged from the sheet transport mechanism 15. The lifting device that raises and lowers the sheet tray 14 will be described later. The transfer sheets S stacked on the sheet tray 14 are removed by the user by pulling out the sheet tray 14 from the first sheet stacking device 8. The sheet transport mechanism 15, which transports the transfer sheet S transported from the image forming device 4 toward the sheet tray 14, is a well-known roller pair consisting of a drive roller 15a and a driven roller 15b. The sheet transport mechanism 15 receives the transfer sheet S discharged by a supply roller 19 disposed at the most upstream position in the sheet transport direction of the first sheet stacking device 8, and transports it downstream in the sheet transport direction. The sheet leading edge detection sensor 17 is disposed upstream of the sheet transport mechanism 15 in the sheet transport direction, and detects the leading edge of the transfer sheet S being transported and outputs a signal.

[0015] The guide mechanism 16, which is arranged downstream of the sheet conveying mechanism 15 in the sheet conveying direction, holds the leading edge of the transfer sheet S being conveyed by the sheet conveying mechanism 15, and conveys the transfer sheet S in the sheet conveying direction at a speed faster than the sheet conveying speed of the sheet conveying mechanism 15. The guide mechanism 16 holds the leading edge of the transfer sheet S, and moves away from the leading edge of the transfer sheet S at a release position, functioning as a guide member that guides the conveyed transfer sheet S onto the sheet tray 14. The guide mechanism 16 has a runnable endless conveyor belt 22 stretched over a drive roller 20 and a driven roller 21, and a holding member 23 attached to the conveyor belt 22 and moving as the conveyor belt 22 runs. The running speed of the conveyor belt 22 is made variable by a motor 24, which is a variable-speed stepping motor that drives the drive roller 20, and the position of the holding member 23 on the conveyor belt 22 can be determined based on the number of steps. As shown in Fig. 3, four conveyor belts 22 are arranged parallel to each other in the sheet width direction indicated by the symbol B, which is the width direction of the transfer sheet S, and two holding members 23 are provided on each of the conveyor belts 22a, 22b, 22b, 22a, and are arranged in positions that are point-symmetrical with each other in the circumferential direction of the conveyor belt 22. The holding members 23 are attached to the outer side in the circumferential direction of the conveyor belt 22 and move as the conveyor belt 22 travels. In Fig. 3, the symbol A indicates the sheet conveying direction.

[0016] The first sheet stacking device 8 uses the speed difference between the sheet conveying speed of the sheet conveying mechanism 15 and the sheet conveying speed of the guide mechanism 16 to detach the transfer sheet S held by the holding member 23 from the holding member 23, and stacks the detached transfer sheet S on the sheet tray 14. A blower fan 25 is provided at a location downstream in the sheet conveying direction of the guide mechanism 16 as a blower member that applies an air flow to the conveyed transfer sheet S in a direction toward the top of the sheet tray 14, i.e., a direction toward the downward side. The blower fan 25 is always in operation, and applies an air flow so as to press the transfer sheet S held by the holding member 23 against the sheet tray 14.

[0017] As shown in Fig. 2, holding member 23 has opening 23a through which the leading edge of transfer sheet S is inserted, and clamping portion 23b that clamps the leading edge of transfer sheet S inserted through opening 23a. The force with which clamping portion 23b clamps the leading edge of transfer sheet S is set to be smaller than the frictional force between sheet conveying mechanism 15 and transfer sheet S. As a result, clamping portion 23b allows transfer sheet S, which has been conveyed by sheet conveying mechanism 15 and inserted through opening 23a, to enter holding member 23, which is stopped at the standby position shown in Fig. 2, due to the rigidity of transfer sheet S, and holds the entered transfer sheet S with its elasticity. The contact surface of the holding member 23 with the transfer sheet S is preferably made of a highly smooth material such as metal or resin, so that the transfer sheet S can be smoothly held by the holding member 23.

[0018] 2 when the transfer sheet S is received, and the leading edge of the transfer sheet S is detected by the sheet leading edge detection sensor 17, and after the leading edge of the transfer sheet S is clamped by the clamping section 23b, the holding member 23 starts conveying the transfer sheet S at a predetermined timing. In this way, the holding member 23 holds the leading edge of the transfer sheet S conveyed by the sheet conveying mechanism 15 at the standby position, and then moves in the sheet conveying direction to function as a guide member that guides the conveyance of the transfer sheet S. 2 and 3, in the image forming apparatus 1, two holding members 23 are arranged on the outer peripheral surface of the conveyor belt 22, with their phases shifted by 180 degrees from each other. Therefore, once the conveyance of the transfer sheet S is completed, one holding member 23 moves half a revolution as the conveyor belt 22 moves, and the other holding member 23 stops at the standby position. In this way, by alternately moving the two holding members 23 to the standby position, the time it takes for the holding members 23 to return to the standby position is shortened, and the conveyance cycle of the transfer sheet S can be improved.

[0019] 3, in the image forming apparatus 1, four conveyor belts 22 are provided in the sheet width direction, and two holding members 23 are arranged on each conveyor belt 22. As a result, compared to a configuration in which one or two conveyor belts 22 are provided and two holding members 23 are provided per belt, the holding members 23 can be made smaller, reducing the inertial load when the conveyor belt 22 is running, and increasing the number of holding members 23 makes it possible to stabilize the holding posture of the transfer sheet S.

[0020] The four conveyor belts 22a, 22b, 22b, 22a are classified into end belts 22a, 22a located at each end in the sheet width direction, and central belts 22b, 22b located between the end belts 22a, 22a. The holding members 23 of the end belts 22a, 22a and the central belts 22b, 22b are arranged so that their attachment positions in the sheet conveying direction are different from each other. Specifically, the holding members 23 of the central belts 22b, 22b are positioned upstream in the sheet conveying direction compared to the holding members 23 of the end belts 22a, 22a. With the above-described configuration, the timing at which the transfer sheet S is held by the holding member 23 can be shifted between the end side belts 22a, 22a and the center side belts 22b, 22b, thereby reducing the load on the transfer sheet S when it enters the holding member 23. In addition, the timing at which the transfer sheet S leaves the holding member 23 is also shifted, so the transfer sheet S can be maintained in a stable position.

[0021] As shown in Fig. 3, the sheet transport mechanism 15 is composed of two pairs of rollers, each pair having a drive roller 15a and a driven roller 15b, and each pair of rollers is configured in a strip so as to be positioned between each of the transport belts 22a, 22b, 22b, 22a. In Fig. 3, the drive roller 15a is disposed on the upper side of the transfer sheet S, and the driven roller 15b is disposed on the lower side of the transfer sheet S, but the configuration is not limited to this.

[0022] Next, we will explain the lifting device that raises and lowers the sheet tray 14. As shown in Fig. 4, the sheet tray 14 has a stack of transfer sheets S stacked on it via a pallet 26, and the sheet tray 14 is configured to be able to be raised and lowered by a lifting device 27. The lifting device 27 includes a pair of pulleys 28a, 28b, a pair of chains 29a, 29b, a pair of weights 30a, 30b, an upper limit detection sensor 31, and a lower limit detection sensor 32. Note that the transfer sheets S may be placed directly on the sheet tray 14 without using the pallet 26. The pair of pulleys 28a, 28b are rotatably supported on the housing of the image forming apparatus 1 at positions above the sheet tray 14 and spaced apart from each other in the sheet conveying direction indicated by the symbol A. A pair of chains 29a, 29b are stretched over the corresponding pulleys 28a, 28b, and one end is connected to the sheet tray 14 and the other end is connected to the corresponding weights 30a, 30b, respectively. When the pulleys 28a and 28b rotate in a first direction (in FIG. 4, the pulley 28a rotates clockwise and the pulley 28b rotates counterclockwise), the sheet tray 14 rises and the weights 30a and 30b fall. On the other hand, when the pulleys 28a and 28b rotate in a second direction opposite to the first direction (in FIG. 4, the pulley 28a rotates counterclockwise and the pulley 28b rotates clockwise), the sheet tray 14 falls and the weights 30a and 30b rise.

[0023] The upper limit detection sensor 31 detects whether the top transfer sheet S stacked on the sheet tray 14 has reached the upper limit position, which is the limit position to which the lifting device 27 is allowed to lift. The upper limit detection sensor 31, located above the sheet tray 14, is a reflective optical sensor that includes, for example, a light-emitting element that emits light and a light-receiving element that receives light that is output from the light-emitting element and reflected by the transfer sheet S. The upper limit detection sensor 31 outputs a detection signal to a control means (not shown) when a transfer sheet S is present on the detection light path, i.e., when the topmost transfer sheet S stacked on the sheet tray 14 reaches the upper limit position. On the other hand, the upper limit detection sensor 31 does not output a detection signal when a transfer sheet S is not present on the detection light path. The upper limit detection sensor 31 may be a reflective or transmissive optical sensor. The control means (not shown) immediately stops the lifting operation of the sheet tray 14 when it receives a detection signal indicating the upper limit position.

[0024] The lower limit detection sensor 32 detects whether the maximum capacity of transfer sheets S is loaded on the sheet tray 14 and whether the sheet tray 14 has reached the lowest position, which is the limit position to which it is allowed to descend. The lower limit detection sensor 32, which is positioned opposite the weight 30b when the sheet tray 14 is fully loaded, is, for example, a reflective optical sensor similar to the upper limit detection sensor 31. The lower limit detection sensor 32 outputs a detection signal to a control means (not shown) when the sheet tray 14 is present on the detection light path, i.e., when the sheet tray 14 is fully loaded and reaches the lower limit position. On the other hand, the lower limit detection sensor 32 does not output a detection signal when the sheet tray 14 is not present on the detection light path. The lower limit detection sensor 32 may be a reflective or transmissive optical sensor. When the control means (not shown) receives the lower limit position detection signal, it immediately stops the downward movement of the sheet tray 14.

[0025] Next, we will explain the sheet conveying process by the above-mentioned first sheet stacking device 8. Note that since the stacking of transfer sheets S in the first sheet stacking device 8 and the stacking of transfer sheets S in the second sheet stacking device 9 can be achieved with the same configuration and control, only the first sheet stacking device 8 will be explained here. First, the first sheet stacking device 8 acquires length information of the transfer sheet S to be transported and stacked. Specifically, it uses size information based on the length and width of the transfer sheet S detected by the sheet size detection sensor 11, or size information of the transfer sheet S input by the user via the operation unit 10. Next, as the sheet feeder 2, sheet position correction device 3, and imaging device 4 are driven, the transfer sheet S on which an image has been formed is transported to the first sheet stacking device 8, and the supply roller 19 begins transporting the transfer sheet S that has been sent after the image has been formed by the imaging device 4, and the sheet transport mechanism 15 is driven. At this time, the guide mechanism 16 is stopped in the standby state shown in FIG. 2 where the holding member 23 is stopped in the standby position, and the blower fan 25 starts operating to always maintain a constant air volume.

[0026] Thereafter, it is determined whether the sheet leading edge detection sensor 17 has detected the leading edge of the transfer 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 starting from the time when the leading edge of the transfer sheet S was detected. This first predetermined time is determined in advance according to the size of the transfer sheet S being conveyed. When the first predetermined time has elapsed, the conveyor belt 22 starts to run, and the holding member 23, which has been stopped in the standby position, starts to move in the sheet conveyance direction. At this time, because the conveyance speed of the transfer sheet S by the sheet conveyance mechanism 15 is faster than the movement speed of the holding member 23, the leading edge of the transfer sheet S enters the holding member 23 through the opening 23a, and the entered leading edge is clamped and held by the clamping portion 23b.

[0027] The movement speed of the holding member 23, i.e., the drive speed of the motor 24 that drives the transport belt 22, is controlled by a control means (not shown) so that the conveyance speed of the transfer sheet S by the sheet conveyance mechanism 15 and the movement speed of the holding member 23 are equal when the entry of the transfer sheet S into the holding member 23 is complete. In this way, the leading edge of the transfer sheet S enters the inside of the holding member 23 due to the speed difference until the movement speed of the holding member 23 becomes equal to the conveyance speed of the transfer sheet S by the sheet conveyance mechanism 15. The time from when the holding member 23 starts to move to when the entry of the transfer sheet S into the holding member 23 is complete is the second predetermined time. The amount of entry of the leading edge of the transfer sheet S into the holding member 23 corresponding to the first and second predetermined times at this time is the predetermined amount C shown in FIG. 5.

[0028] When the holding member 23 holds the transfer sheet S, that is, when the leading edge of the transfer sheet S has penetrated into the holding member 23 by a predetermined amount C, a first acceleration is performed in the movement speed of the holding member 23, and a third predetermined time is measured according to the previously acquired size information of the transfer sheet S. The speed difference between the conveyance speed of the transfer sheet S by the sheet conveying mechanism 15 and the movement speed of the holding member 23, which is generated by the first acceleration, is used to start conveying and moving the transfer sheet S by the sheet conveying mechanism 15 and the guide mechanism 16. At this time, the movement speed of the holding member 23 becomes faster than the conveyance speed of the transfer sheet S by the sheet conveying mechanism 15, and the leading edge of the transfer sheet S is conveyed while being pulled by the holding member 23, which prevents the transfer sheet S from bending compared to when the speed is constant. During this transport, the force with which the holding member 23 holds the transfer sheet S is smaller than the frictional force between the sheet transport mechanism 15 and the transfer sheet S, so the transfer sheet S gradually comes off the holding member 23, but the state in which the transfer sheet S is held by the holding member 23 is maintained from the position where the transfer sheet S is held to the position where the transfer sheet S is released.

[0029] When a third predetermined time has elapsed since the holding member 23 began to hold the transfer sheet S, a second acceleration occurs in the movement speed of the holding member 23, and the movement speed of the holding member 23 is further accelerated, causing the transfer sheet S to separate from the holding member 23. Note that even if the transfer sheet S leaves the sheet transport mechanism 15 before it separates from the holding member 23, the inertial force of the transfer sheet S will cause the transfer sheet S to separate from the holding member 23. Figure 6 shows the state when the transfer sheet S has been separated from the holding member 23. In Figure 6, the symbol D indicates the acceleration position, which is the position of the holding member 23 where the second acceleration occurs, and the symbol E indicates the separation position, which is the position of the holding member 23 where the transfer sheet S is separated.

[0030] Figure 7 shows a case where a small size transfer sheet S1, which is smaller than the transfer sheet S, is used instead of the transfer sheet S. As shown in Figure 7, a control means (not shown) adjusts the acceleration position D and the release position E to match the small size transfer sheet S1, and the small size transfer sheet S1 is released from the holding member 23 due to the speed difference between the conveying speed of the small size transfer sheet S1 by the sheet conveying mechanism 15 caused by the second acceleration and the moving speed of the holding member 23. The transfer sheet S or small size transfer sheet S1 that has left the sheet transport mechanism 15 and separated from the holding member 23 receives wind force from the blower fan 25 and falls toward the sheet tray 14, where it is stacked.

[0031] When the transfer sheet S or small size transfer sheet S1 is released from the holding member 23, a fourth predetermined time is counted according to the previously acquired size information of the transfer sheet S or small size transfer sheet S1, and when the fourth predetermined time has elapsed, the holding member 23 begins to decelerate and stops at the standby position. Thereafter, it is determined whether the image forming operation in the image forming device 4 is complete, and if it is determined that it is not complete, it is determined whether the sheet leading edge detection sensor 17 has detected the leading edge of the transfer sheet S, and the above-mentioned operation is repeated until the image forming operation is complete. If it is determined that it is complete, the operation of the conveying member 6 and the blower fan 15 is stopped.

[0032] FIG. 8 shows the sheet tray 14 of the first sheet stacking device 8 as viewed from downstream toward upstream in the sheet conveyance direction. In the figure, a marking device 33 is disposed to the right of the sheet tray 14, i.e., on the front side of the image forming apparatus 1. As shown in FIG. 8, the marking device 33 is a device that forms specific divisions in the stack of sheets by inserting thin sheet-like markers 34 into the transfer sheets S stacked on the sheet tray 14 for every desired number of sheets so that the markers protrude from the stack of sheets. Hereinafter, the target ejected from the marking device 33 will be referred to as a marker. The markers 34 are, for example, thin sheet-like media, but the shape, material, etc. of the markers are not limited. As shown in Fig. 9, the marking device 33 is disposed at a position near the downstream end in the sheet conveying direction of the transfer sheet S loaded on the sheet tray 14. This is because if the marking device 33 is disposed near the upstream end in the sheet conveying direction of the transfer sheet S loaded on the sheet tray 14, when the transported transfer sheet S is not loaded onto the sheet tray 14 from directly above but is loaded at a speed in the sheet conveying direction, the transfer sheet S may move the marker 34, causing the marker 34 to fall. Below, the marking device 33 will be described using Fig. 10.

[0033] 10, the marking device 33 has a marker storage section 35 that stores a continuous roll of markers 34 used when sorting transfer sheets S based on the image formation information set in the image forming apparatus 1, and a marker transport section 36 that transports the markers 34 from the marker storage section 35 to the outside. The marker storage section 35 has a sealed box shape and has an outlet 35a on one side for discharging the markers 34 to the outside. The marker transport section 36 includes a roller pair 37 having a drive roller 37a and a driven roller 37b that sandwich and transport the marker 34, and a tension roller 38 that applies tension to the marker 34. The drive roller 37a, which has a V-groove on its circumferential surface, is driven to rotate by a motor 39 (described later), and the driven roller 37b, which has an outer shape that fits into the V-groove of the drive roller 37a, rotates in response to the rotation of the drive roller 37a. The tension roller 38, which is biased by a biasing means (not shown) and applies a predetermined tension to the marker 34, also rotates in response to the movement of the marker 34 as it is sandwiched and transported by the roller pair 37. With this configuration, the marker 34 that passes through the roller pair 37 is bent into a V-shaped cross section, and the marker 34 remains straight even after leaving the roller pair 37.

[0034] A cutter 40 is provided between the roller pair 37 and the discharge port 35a to cut the markers 34 that are discharged to the outside through the discharge port 35a. The cutter 40 has a fixed blade 40a arranged above the passing markers 34 and a movable blade 40b arranged below the passing markers 34. The movable blade 40b is moved upward by a motor 39, which will be described later, and cuts the markers 34 by pinching them between itself and the fixed blade 40a. A motor 39 that drives the drive roller 37a and the movable blade 40b is disposed inside the marker storage unit 35. The motor 39, which can rotate in both directions, is drivingly connected to the drive roller 37a and the movable blade 40b via a one-way clutch (not shown), and drives the drive roller 37a to rotate when operating in either the forward or reverse direction, and moves the movable blade 40b when operating in the other direction.

[0035] Here, the problems with the first sheet stacking device 8 will be explained. As shown in Figure 11(a), transfer sheet S is transported to first sheet stacking device 8, and as shown in Figure 11(b), when the transported transfer sheet S reaches a predetermined position, marker 34 is ejected from marking device 33, and marker 34 cut from the roll is placed on the uppermost transfer sheet S. Thereafter, holding member 23 transports transfer sheet S, and when the leading edge of transfer sheet S separates from holding member 23, the separated transfer sheet S falls onto the placed marker 34. At this time, as shown by the arrow in Figure 11(c), a fan wind, which is the wind blown up when transfer sheet S is placed, acts on marker 34, and marker 34 hit by the fan wind falls from the sheet stack as shown in Figure 11(d), causing a problem that it does not function as a separator.

[0036] To address this issue, a known technique is to not cut the marker 34 until the subsequent transfer sheet S has completely fallen onto the sheet stack, and to integrate the marker 34 with the roll when the fan is in operation to prevent the marker 34 from being blown away. However, even this technique has the limitation that the height at which the marker 34 is ejected must be the same as the height of the top sheet of the sheet stack. If the marker ejection height is different from the height of the sheet stack, the roll-side end of the marker 34, which is integrated with the roll, will float above the sheet stack, causing the end of the transfer sheet S placed on the marker 34 to also float. This can lead to incorrect detection of the sheet stack height and resulting in poor transport and stacking of the transfer sheet S. Furthermore, the roll-side end of the marker 34 after cutting can lean against the marking device 33, blocking the marker 34 ejection port and causing marker ejection failure. The leaning can also result in the marker 34 being inserted too shallowly into the sheet stack, causing the marker 34 to fail to reach small-sized transfer sheets S.

[0037] The configuration of the present invention that solves the above-mentioned problems will be described below. Figure 12 shows a marking device 41 employing the first embodiment of the present invention. Marking device 41 differs from marking device 33 shown in Figure 10 only in that it has a guide member 42, and the other configurations are the same. The guide member 42 is formed from a plate-like member with an L-shaped cross section, and has a main body portion 42a and a guide portion 42b. The main body portion 42a has an elongated hole 42c in the longitudinal direction, and the guide portion 42b, which is integrally formed with the main body portion 42a, is bent at a substantially right angle to the main body portion 42a, and its lower end extends downward beyond the main body portion 42a.

[0038] The guide member 42 is supported so as to be movable up and down relative to the marker storage section 35 by two shoulder screws 43 that fit into the elongated holes 42c and screw into one side surface 35b of the marker storage section 35. When the guide member 42 moves up and down, it is guided by the elongated holes 42c, the shoulder screws 43, and one side surface 35b, and these members form a guide section 44. The guide member 42 falls downward due to its own weight within the range of the elongated hole 42c, and is positioned at the lowest position when the shoulder screw 43 abuts against the elongated hole 42c. When the guide member 42 moves downward to its lowest position, as shown in FIG. 13, its lower portion is positioned below the uppermost transfer sheet S stacked on the sheet tray 14, and its upper portion is positioned above the discharge opening 35a, i.e., at a position where it can guide the ejected marker 34. Note that the positioning of the guide member 42 at its lowest position may depend on the shape of the elongated hole 42, or a stopper (not shown) may be provided to stop the descent of the guide member 42. In the example shown in FIG. 13, the lower end of the guide member 42 abuts against the sheet placement surface of the sheet tray 14, stopping the descent of the guide member 42, and the sheet tray 14 functions as a stopper.

[0039] The guide member 42 is disposed on the left side of the discharge outlet 35a in Fig. 12(b) because the marking device 41 is disposed on the left side in the sheet conveying direction, i.e., on the front side of the device, and the left side of the discharge outlet 35a in Fig. 12(b) corresponds to the upstream side in the sheet conveying direction. With the above-described configuration, when a transfer sheet S is placed on the top transfer sheet S placed on the sheet tray 14, even if a fan wind acts on the marker 34 placed on the top transfer sheet S, the marker 34 is guided by the guide member 42 arranged in the direction of the fan wind. This prevents the marker 34 from falling off the top transfer sheet S, and makes it possible to provide a first sheet stacking device 8 that can place the marker 34 on the sheet stack without being affected by the fan wind.

[0040] In the above-described configuration, the guide member 42 is configured to be vertically movable, but the guide member 42 may also be configured to be fixed. However, if a fixed guide member 42 is applied to a sheet tray 14 having an elevator device 27, the sheet tray 14 or pallet 26 will rise to the position of the upper limit detection sensor 31, and therefore, if the guide member 42 is extended below the upper limit detection sensor 31, it will interfere with the sheet tray 14 or pallet 26. To prevent this, it is desirable that the guide member 42 be configured to be vertically movable. 13, when there are few stacked sheet bundles, the sheet tray 14 approaches the marking device 41, but if the guide member 42 is vertically movable, the guide member 42 retreats upward while contacting the sheet tray 14, thereby preventing damage to the guide member 42 due to interference and achieving the above-mentioned effects. The marking device 41 and the guide member 42 are disposed outside the stacking position of the transfer sheets S on the sheet tray 14.

[0041] 14 shows a marking device 45 used in a second embodiment of the present invention. Marking device 45 differs from marking device 41 in that it uses guide member 46 instead of guide member 42, but the other configurations are the same. The guide member 46 is formed from a plate-like member with an L-shaped cross section and has a main body portion 46a and a guide portion 46b, which are movable portions. The guide portion 46b, which is integrally formed with the main body portion 46a, is bent at a substantially right angle to the main body portion 46a, and its lower end extends downward beyond the main body portion 46a. Support members 47, each having a semicircular hole, are fixed at two positions, one above the other, at the bend between the main body portion 46a and the other at a vertical position. Each support member 47 is fitted with a support pin 48, whose cross section is shaped to fit into the corresponding semicircular hole. The support pins 48, which are fixed portions, are fixed to a non-moving member (not shown) of the first sheet stacking device 8 via a bracket (not shown). The guide member 46 is composed of the main body portion 46a, the guide portion 46b, the support member 47, and the support pins 48.

[0042] Guide member 46 is supported by support pins 48 that are fitted into each support member 47 and fixed to a non-moving member (not shown) of first sheet stacking device 8 so as to be vertically movable relative to one side surface 35b of marker storage section 35. When guide member 46 moves up and down, it is guided by each support member 47, support pins 48, and one side surface 35b, and these members form guide section 49. Note that support pin 48 has a semicircular cross section and is configured to abut against guide section 46b and suppress rotation of guide member 46 when it moves up and down, but it may have a circular cross section or may have another shape as long as rotation is sufficiently suppressed by one side surface 35b. The guide member 46 falls downward due to its own weight, and is positioned at the lowest position when a part of it abuts against a stopper (not shown). When the guide member 46 moves downward and reaches the lowest position, similar to the guide member 42, its lower part is positioned below the uppermost transfer sheet S stacked on the sheet tray 14, and its upper part is positioned above the discharge opening 35a.

[0043] The above-described configuration can obtain the same effects as those of the first embodiment, and can reduce the sliding resistance of the guide portion 49 compared to the guide portion 44 in the first embodiment, allowing the guide member 46 to move up and down smoothly. In each of the above-described embodiments, a configuration is used in which guide member 42 or guide member 46 is used, but each guide member 42, 46 may be configured so that its vertical length is equal to or greater than the length from above discharge outlet 35a to a position below the detection position of upper limit detection sensor 31, i.e., the length indicated by symbol L in FIG. 13. Furthermore, in each of the marking devices 41, 45, the guide members 42, 46 are configured to be able to move up and down freely and descend under their own weight, but it is also possible to adopt a configuration in which a biasing force from above to below is imparted by a biasing means such as a spring, or a configuration in which the guide members move up and down by a driving means such as a motor.

[0044] 15 shows a marking device 50 used in a third embodiment of the present invention. Marking device 50 differs from marking device 41 in that it includes a second guide member 51, but the other configurations are the same. 15(b), the second guide member 51 is formed from a plate-like member having an L-shaped cross section that is bent so as to be symmetrical with the guide member 42 about the Z axis, and has a main body portion 51a and a guide portion 51b. The main body portion 51a has an elongated hole 51c in the longitudinal direction, and the lower end of the guide portion 51b extends downward beyond the main body portion 51a.

[0045] The second guide member 51 is supported by two shoulder screws 43 fitted into the elongated holes 51c so as to be movable up and down relative to the marker storage section 35. When the second guide member 51 moves up and down, it is guided by the elongated holes 51c, the shoulder screws 43, and one side surface 35b, and these members form a guide section 52. The second guide member 51 falls downward due to its own weight within the range of the elongated hole 51c, and is positioned at the lowest position when the shoulder screw 43 abuts against the elongated hole 51c. Similar to the guide member 42, the second guide member 51 is configured such that when it moves downward to occupy the lowest position, its lower portion is positioned below the uppermost transfer sheet S stacked on the sheet tray 14, and its upper portion is positioned above the discharge port 35a and can guide the marker 34 being ejected.

[0046] The second guide member 51 is arranged so as to be symmetrical with the guide member 42 across the Z axis in FIG. 15(b), that is, to the right of the discharge opening 35a and facing the guide member 42 across the discharge opening 35a. With the above-described configuration, even if air from the blower fan 25 acts on the marker 34 placed on the top transfer sheet S before the above-described fan air acts on it, the second guide member 51 arranged in the direction of the air blowing can prevent the marker 34 from moving. This makes it possible to hold the marker 34 between the guide members 42, 51, prevent the marker 34 from falling off the top transfer sheet S, and provide a first sheet stacking device 8 that can place the marker 34 on the sheet stack without being affected by the air from the fan and the air from the blower fan 25.

[0047] 16 shows a marking device 53 used in a fourth embodiment of the present invention. Marking device 53 differs from marking device 45 in that it includes a second guide member 54, but the other configurations are the same. The second guide member 54 is formed from a plate-like member with an L-shaped cross section that is bent so as to be symmetrical to the guide member 46 about the Z axis in FIG. 16(b), and includes a main body portion 54a and a guide portion 54b, which are movable portions. The main body portion 54a and the guide portion 54b are integrally formed, and the lower end of the guide portion 54b extends downward from the main body portion 54a. Two support members 47, which are movable portions, are fixed to the bent portion between the main body portion 54a and the guide portion 54b in the vertical direction, and each support member 47 is fitted with a support pin 48, which is fixed to a stationary member (not shown) of the first sheet stacking device 8 via a bracket (not shown). The second guide member 54 is composed of the main body portion 54a, the guide portion 54b, the support member 47, and the support pin 48.

[0048] The second guide member 54 is supported by the support pins 48 so as to be movable up and down relative to the one side surface 35b. When the second guide member 54 moves up and down, it is guided by the support members 47, the support pins 48, and the one side surface 35b, and these members form a guide section 55. The second guide member 54 falls downward due to its own weight, and is positioned at the lowest position when a part of it abuts against a stopper (not shown). When the second guide member 54 moves downward and reaches the lowest position, similar to the second guide member 51, its lower part is positioned below the uppermost transfer sheet S stacked on the sheet tray 14, and its upper part is positioned above the discharge opening 35a.

[0049] The above-described configuration can obtain the same effects as the third embodiment, and can also reduce the sliding resistance of guide portion 55 compared to guide portion 52, allowing the second guide member 54 to move up and down smoothly. In each of the third and fourth embodiments, the length of each second guide member 51, 54 may be configured to extend from above the discharge port 35a to a position below the detection position of the upper limit detection sensor 31. Furthermore, in each marking device 50, 53, each second guide member 51, 54 is configured to be able to move up and down freely and descend under its own weight, but it is also possible to adopt a configuration in which a biasing force from above to below is applied by a biasing means such as a spring, or a configuration in which it moves up and down by a driving means such as a motor.

[0050] 17 shows a marking device 56 used in a fifth embodiment of the present invention. Marking device 56 differs from marking device 50 in that it includes guide member 57 and second guide member 58 instead of guide member 42 and second guide member 51, but the rest of the configuration is the same. Like guide member 42, guide member 57 has a main body portion 57a, a guide portion 57b, and an elongated hole 57c. Guide member 57 differs from guide member 42 only in that guide portion 57b has a bent portion 57d near the lower end thereof that is inclined downward in a direction away from second guide member 58, in other words, bent; otherwise, guide member 57 is identical in configuration. Guide member 57 is guided by elongated hole 57c, shoulder screws 43, and one side surface 35b when moving up and down, and these members form guide portion 59.

[0051] Similar to second guide member 51, second guide member 58 has a main body portion 58a, a guide portion 58b, and an elongated hole 58c. Second guide member 58 differs from second guide member 51 only in that it has a bent portion 58d near the lower end of guide portion 58b that is inclined downwards, away from guide member 57, in other words, bent, but the other configurations are the same. When second guide member 58 moves up and down, it is guided by elongated hole 58c, shoulder screws 43, and one side surface 35b, and these members form guide portion 60.

[0052] Here, the effects of the fifth embodiment will be described. 18(a) shows a case in which the guide member 42 and the second guide member 51 are both lowered in the marking device 50 shown in the third embodiment, with the marker 34 placed on the sheet stack positioned in the space between them. As shown in the figure, if an external force such as airflow from the blower fan 25 acts on the marker 34 placed on the sheet stack, or if the position of the marker 34 is unstable during cutting, the marker 34 may not be properly placed on the sheet stack and may lean against one of the guide portions 51b. In such a case, if the sheet tray 14 is raised or lowered in preparation for the next image forming operation or due to an input by the device operator, the marker 34, which has been lowered together with the sheet stack on the sheet tray 14, will first pass through the space between the guide portions 42b, 51b and then re-enter the space between the guide portions 42b, 51b.

[0053] When the marker 34 leaning against one guide portion 51b moves down and leaves the space between the guide portions 42b, 51b, the marker 34 changes position on the sheet stack from the state indicated by the broken line to the state indicated by the solid line, as shown in Fig. 18(b). When the sheet tray 14 moves up from this state, the marker 34, whose position on the sheet stack has changed, cannot return to the space between the guide portions 42b, 51b, but instead comes into contact with one guide portion 51b and falls off the sheet stack, as shown in Fig. 18(c), causing the problem of it no longer functioning as a marker.

[0054] 19(a) shows a state in which the guide member 57 and the second guide member 58 are both lowered and the marker 34 placed on the sheet stack is positioned in the space between them in the marking device 56 shown in the fifth embodiment. In the state shown in FIG. 19(a), the marker 34 is leaning against one guide portion 58b. The following describes what happens when the sheet tray 14 is raised or lowered from this state. When the sheet tray 14 is lowered and the marker 34 that was leaning against one of the guide portions 58b is released from the space between the guide portions 57b and 58b, as shown in Figure 19(b), the marker 34 that was leaning against it changes from the state shown by the dashed line to the state shown by the solid line, and its placement position on the sheet stack changes.

[0055] When the sheet tray 14 is raised from the state shown in Figure 19(b), the marker 34, whose placement position on the sheet stack has changed, abuts against the inner surface of the bending portion 58d of the second guide member 58, is scooped up by the inner surface of the bending portion 58d, and its placement position on the sheet stack is changed from the dashed line position to the solid line position, and it is able to enter the space between the guide portions 57b and 58b again, as shown in Figure 19(c). This prevents the problems encountered in the third embodiment described above, and even if the marker 34 leaning against one of the guide portions 58 falls out of the space between the guide portions 57b, 58b, it can easily return to its original space, allowing the marker 34 to continue functioning.

[0056] In the explanation of the problems and effects of this embodiment, the guide portion 51b and the guide portion 58b are shown as one of the guide portions, but the guide portion 42b and the guide portion 57b may also be used as one of the guide portions. Furthermore, in the fifth embodiment, guide member 57 and second guide member 58 are formed by providing bending portions in guide member 42 and second guide member 51 that constitute marking device 50, respectively, but guide member 57 and second guide member 58 may also be formed by providing bending portions in guide member 46 and second guide member 54 that constitute marking device 53, respectively. In this case, it is possible to employ a configuration in which each bending portion is provided with a groove into which support pin 48 can fit, or a configuration in which brackets are provided to separate each support pin 48 from the bending portion so that each support pin 48 does not interfere with each bending portion, or the like.

[0057] 20 shows a marking device 61 used in a sixth embodiment of the present invention. Marking device 61 differs from marking device 53 in that it uses guide member 62 and second guide member 63 instead of guide member 46 and second guide member 54, but the other configurations are the same. The guide member 62 has a main body 62a made of a plate-like member with an L-shaped cross section, and a rectangular column-shaped guide portion 62b attached integrally to the main body 62a. The lower end of the guide portion 62b extends downward beyond the main body 62a, and an inclined surface portion 62c is formed at the tip of the lower end, inclined in a direction away from the roller pair 37 as it extends downward, in other words, in a direction away from the second guide member 63 as it extends downward. The main body 62a and the guide portion 62b form a movable portion. A support member 64 is disposed at the bent portion of the main body 62a. The support member 64 has two support portions 64a with rectangular holes into which the guide portions 62b can fit so as to be movable up and down. The support member 64, which is a fixed portion, is fixed to a non-moving member (not shown) of the first sheet stacking member 8 via a bracket (not shown). When the guide member 62 moves up and down, it is guided by the guide portions 62b, the support member 64, and one side surface 35b, and these members form a guide portion 66.

[0058] The second guide member 63 has a main body 63a made of a plate-like member with an L-shaped cross section that is bent so as to be line-symmetrical to the guide member 62 across the Z axis in Figure 20(b), and a rectangular column-shaped guide portion 63b that is attached integrally to the main body 63a. The lower end of the guide portion 63b extends downward beyond the main body 63a, and an inclined surface 63c is formed at the tip of the lower end so as to be inclined in a direction away from the guide member 62 as it extends downward. The main body 63a and the guide portion 63b form a movable portion. A support member 65 having two support portions 65a with rectangular holes into which the guide portions 63b can fit for vertical movement is disposed at the bent portion of the main body portion 63a. The support member 65, which is a fixed portion, is fixed to a non-moving member (not shown) of the first sheet stacking member 8 via a bracket (not shown). The second guide member 63 is guided by the guide portions 63b, the support member 64, and one side surface 35b during vertical movement, and these members form a guide portion 67.

[0059] According to the sixth embodiment described above, it is possible to obtain the same effects as in the fifth embodiment, and also to simplify the device configuration, thereby achieving cost reduction and downsizing of the device. In the sixth embodiment, the guide portions 62b, 63b are prismatic and the holes formed in the corresponding support portions 64a, 65a are rectangular, but the guide portions 62b, 63b may be cylindrical and the holes formed in the corresponding support portions 64a, 65a may be circular. Furthermore, the shapes of the guide portions 62b, 63b and the holes formed in the corresponding support portions 64a, 65a may be any shapes as long as they allow the guide member 62 and the second guide member 63 to move up and down smoothly.

[0060] The configuration of the sixth embodiment described above may be applied to guide member 46 in the second embodiment shown in Fig. 14. In this case, a guide portion similar to guide portion 62b and a support member similar to support member 64 are used instead of guide portion 46b and support pin 48, and the movable portion is formed by main body portion 46a and the guide portion, and the fixed portion is formed by the support member. The configuration of the sixth embodiment may also be applied to the second guide member 54 in the fourth embodiment shown in Fig. 16. In this case, a guide portion similar to guide portion 62b and a support member similar to support member 64 are used instead of guide portion 54b and support pin 48, and the movable portion is constituted by main body portion 54a and the guide portion, and the fixed portion is constituted by the support member.

[0061] In each of the third to sixth embodiments described above, when a marker 34 is placed on the top transfer sheet S of a sheet stack and the sheet tray 14 is lowered in preparation for the next image forming operation or by an operator, the marker 34 falls out of the space between the guide members. In this state, the guide members do not function to guide the marker 34, so there is a risk that the marker 34 may shift or fall off the sheet stack when the blower fan 25 is operating. Operation control of the sheet stacking device that solves this problem will be described as a seventh embodiment of the present invention.

[0062] FIG. 21 is a flowchart illustrating the operation of the first sheet stacking device 8 in the seventh embodiment. 21, when the image forming apparatus 1 is ready for image formation, the initialization operations of each section of the image forming apparatus 1, including the first sheet stacking device 8, are completed and the blower fan 25 is activated (ST01). Next, it is determined whether the operator of the image forming apparatus 1 has lowered the sheet tray 14 of the first sheet stacking device 8 (ST02), and if it is determined that the lowering operation has not been performed, the image forming operation is performed (ST03). Then, when the image forming operation for one job is completed (ST04), it is determined whether there is a next job (ST05).

[0063] If it is determined in step ST05 that there is a next job, the control means (not shown) that controls the operation of the first sheet stacking device 8 first sends an operation command to lower the sheet tray 14 in order to perform an initialization operation, but prior to this operation command, it sends a command to stop the operation of the blower fan 25. When it is confirmed that the operation of the blower fan 25 has stopped based on this command (ST06), the lifting device 27 is operated to lower the sheet tray 14 and position it at the lowest position (ST07), and then the initialization operation of the first sheet stacking device 8 is performed (ST08).

[0064] When the sheet tray 14 is lowered to the lowest position in step ST07, the markers 34 placed on the sheet stack in the previous job will fall out of the spaces between the guide members provided in the marking devices 41, 45, 50, 53, and 56. However, because the operation of the blower fan 25 is stopped prior to the lowering of the sheet tray 14, even if the initialization operation is performed in step ST08, no external force due to the air blown from the blower fan 25 will act on the markers 34, and therefore the markers 34 placed on the sheet stack can be prevented from falling or shifting.

[0065] When the initialization operation of the first sheet stacking device 8 is completed in step ST08, the control means (not shown) sends an operation command to lift the sheet tray 14, and the lifting device 27 is activated to lift the sheet tray 14 toward a predetermined position (ST09). Then, when the sheet tray 14 is positioned and stopped at a predetermined position (ST10), the control means (not shown) sends an instruction to start the operation of the blower fan 25, and the blower fan 25 starts operating (ST11). After that, when the initialization operation of all parts of the image forming apparatus 1 is completed, the image forming apparatus 1 becomes ready for image formation (ST12), and image formation operation is performed (ST03). When it is determined in step ST05 that there is no next job, the control means (not shown) sends an instruction to stop the operation of the blower fan 25, and the operation of the blower fan 25 stops (ST13), and the image forming apparatus 1 enters an image formation operation standby state.

[0066] In step ST02, if it is determined that the operator of image forming apparatus 1 has performed an operation to lower sheet tray 14, control means (not shown) sends an operation command to lower sheet tray 14, but prior to this operation command, it sends a command to stop operation of blower fan 25. When it is confirmed that operation of blower fan 25 has stopped based on this command (ST14), lifting device 27 is operated to lower sheet tray 14 and position it at the lowest position (ST15).

[0067] Next, it is determined whether an operation to raise the sheet tray 14 has been performed (ST16), and if it is determined that an operation to raise the sheet tray 14 has been performed, the control means (not shown) sends an operation command to raise the sheet tray 14, and the lifting device 27 is operated to raise the sheet tray 14 to a predetermined position (ST17). Then, when the sheet tray 14 is positioned at the predetermined position and stops (ST18), the control means (not shown) sends a command to start the operation of the blower fan 25, and the blower fan 25 starts operating (ST19), and it is determined in step ST05 whether there is a next job.

[0068] According to the seventh embodiment described above, when the sheet tray 14 is lowered, the markers 34 placed on the sheet stack will fall out of the space between the guide members provided in the marking device. However, since the operation of the blower fan 25 is stopped prior to the lowering of the sheet tray 14, the markers 34 placed on the sheet stack can be prevented from falling or shifting.

[0069] In each of the above embodiments, an example has been shown in which an inkjet recording device that forms full-color images is used as an image forming device to which the present invention can be applied, but the image forming device 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, multifunction machines, etc. In addition, in the above embodiment, a configuration is shown in which a transfer sheet S is used as the sheet, which is the recording medium on which an image is formed, but this transfer 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 film, etc., and any sheet-like material on which an image can be formed may be used.

[0070] The aspects of the present invention are as follows, for example. [1] A sheet stacking device comprising a stacking member on which transfer sheets are loaded, and a transport member that transports the transfer sheets in a sheet transport direction toward the stacking member, and a marking device that ejects and places a marker on the top surface of the top sheet, which is the top transfer sheet loaded on the stacking member, for each arbitrary number of sheets loaded, and the marking device has an outlet for discharging the marker, a marker storage unit that stores the marker, a marker transport unit that transports the marker to discharge it from the outlet, and a guide member that guides the marker discharged from the outlet to prevent it from moving in the opposite direction to the sheet transport direction. [2] The sheet stacking device according to [1], wherein the guide member guides the marker to a position below the top sheet. [3] A sheet stacking device according to [1] or [2], characterized in that the stacking member is movable up and down, and the guide member is movable up and down in accordance with the up and down movement of the stacking member, and when the guide member is positioned at the lowest position, the lower part is positioned below the top sheet and the upper part is positioned above the discharge outlet. [4] The sheet stacking device according to [3], wherein the guide member is guided by a guide portion and moves up and down. [5] The sheet stacking device described in [3] or [4] is characterized in that the guide member has a fixed portion and a movable portion, and when the guide member is positioned at the uppermost position, the upper portion of the guide member is positioned lower than the upper end of the marker storage section. [6] A sheet stacking device according to any one of [1] to [5], characterized in that it is provided with an air blowing member that applies an air flow toward the stacking member to the transfer sheet being transported, and the marking device has a second guide member located opposite the guide member through the discharge outlet that guides the marker discharged from the discharge outlet to prevent it from moving in the sheet transport direction. [7] The sheet stacking device described in [6] is characterized in that the stacking member is movable up and down, and the guide member and the second guide member are each movable up and down in accordance with the up and down movement of the stacking member, and the guide member and the second guide member are formed so that the portions near their respective lower ends are inclined or bent in a direction that widens toward each other as they move downward. [8] The sheet stacking device described in [6] is characterized in that the stacking member is freely movable up and down, and the guide member and the second guide member are each freely movable up and down in accordance with the up and down movement of the stacking member, and the operation of the air blowing member is stopped before the stacking member begins its downward movement, and the air blowing member is operated after the stacking member has completed its upward movement. [9] A sheet stacking device as described in [7], characterized in that the operation of the air blowing member is stopped before the stacking member starts its downward movement, and the air blowing member is activated after the stacking member has completed its upward movement.

[10] An image forming apparatus including the sheet stacking device according to any one of [1] to [9].

[0071] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specifically limited in the above description, various modifications and changes are possible within the scope of the spirit of the present invention as described in the claims. 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]

[0072] 1. Image forming device 8 Sheet stacking device (first sheet stacking device) 14 Loading member (sheet tray) 15 Conveying member (sheet conveying mechanism) 25 Ventilation component (blower fan) 34 Marker 35 Marker storage compartment 35a Outlet 36 Marker transport unit 41, 45, 50, 53, 56 Marking device 42, 46, 57 Guide members 44,49,52,55,59,60 Information Department 46a, 54a Movable part (main body) 46b, 54b Movable part (guide part) 48 Fixed part (support pin) 51, 54, 58 Second guide member S sheet (transfer sheet) [Prior art documents] [Patent documents]

[0073] [Patent Document 1] Patent No. 7435014 [Patent Document 2] Japanese Patent Application Publication No. 6-321411 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-98826 [Patent Document 4] Japanese Patent Publication No. 2022-25900

Claims

1. A sheet stacking device including a stacking member on which a transfer sheet is stacked, and a conveying member that conveys the transfer sheet in a sheet conveying direction toward the stacking member, a marking device that ejects a marker onto an upper surface of a top sheet, which is the topmost transfer sheet stacked on the stacking member, for each sheet of a desired number of sheets stacked; The marking device is a marker storage section that includes an outlet for discharging the marker and stores the marker; a marker transport unit that transports the marker so as to discharge the marker from the discharge port; a guide member that guides the marker discharged from the discharge port to prevent the marker from moving in a direction opposite to the sheet conveying direction; A sheet stacking device comprising:

2. 2. The sheet stacking device according to claim 1, The sheet stacking device according to claim 1, wherein the guide member guides the marker to a position below the top sheet.

3. 2. The sheet stacking device according to claim 1, A sheet stacking device characterized in that the stacking member is freely movable up and down, and the guide member is freely movable up and down in accordance with the up and down movement of the stacking member, and when the guide member is located at the lowest position, the lower part is located at a position below the top sheet and the upper part is located at a position above the discharge outlet.

4. 4. The sheet stacking device according to claim 3, The sheet stacking device is characterized in that the guide member moves up and down while being guided by a guide portion.

5. 4. The sheet stacking device according to claim 3, A sheet stacking device characterized in that the guide member has a fixed portion and a movable portion, and when the guide member is positioned at the uppermost position, the upper portion of the guide member is positioned lower than the upper end of the marker storage section.

6. 2. The sheet stacking device according to claim 1, a blower member for blowing air onto the transfer sheet being conveyed in a direction toward the stacking member; A sheet stacking device characterized in that the marking device has a second guide member located opposite the guide member through the discharge outlet, which guides the marker discharged from the discharge outlet to prevent it from moving in the sheet transport direction.

7. 7. The sheet stacking device according to claim 6, the loading member is movable up and down, and the guide member and the second guide member are each movable up and down in accordance with the vertical movement of the loading member, 10. A sheet stacking device according to claim 9, wherein the guide member and the second guide member are formed so that portions near their respective lower ends are inclined or bent in directions that widen toward each other as they extend downward.

8. 7. The sheet stacking device according to claim 6, the loading member is movable up and down, and the guide member and the second guide member are each movable up and down in accordance with the vertical movement of the loading member, 10. A sheet stacking device, comprising: a step of stopping operation of the air blowing member before the stacking member starts to move downward; and a step of operating the air blowing member after the stacking member has completed its upward movement.

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

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