Sheet loading device, post-processing device, and image forming system

Abstract

The system allows for efficient loading of sheets onto the discharge tray at a low loading height without increasing the size or cost of the equipment, or reducing the discharge space on the discharge tray. [Solution] A lower discharge tray 83 (discharge tray) is installed, which has a mounting surface on which sheets P discharged from the discharge section A3 in a predetermined discharge direction can be stacked. In addition, a lifting tray 82, which is configured to be able to move up and down according to the amount of sheets P stacked, is installed above the lower discharge tray 83. The lifting tray 82 has a pressing member 60 installed at its bottom that can press down on the sheets P stacked on the mounting surface of the lower discharge tray 83 from above.

Description

Technical Field

[0001] This invention relates to a sheet loading device for loading sheets in a loadable manner, a post-processing device including the same, and an image forming system.

Background Art

[0002] Conventionally, in a post-processing device connected to an image forming device such as a copying machine or a printer, there is known a device provided with a discharge tray on which sheets that have been subjected to a folding process are discharged and stacked (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 1 discloses a technique for installing a paper bundle pressing member and a paper bundle drawing roller in a stacking tray for the purpose of stacking a sheet that has been subjected to a folding process well on the stacking tray (discharge tray) at a low stacking height.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The sheet loading device of Patent Document 1 has a paper bundle pressing member and a paper bundle drawing roller installed in the discharge tray (stacking tray), so that an effect of being able to stack sheets well on the discharge tray at a low stacking height can be expected. However, since the sheet loading device of Patent Document 1 has a paper bundle pressing member and a paper bundle drawing roller installed in the discharge tray, the device has become larger and more costly, and the discharge space on the discharge tray has been narrowed.

[0005] This invention has been made to solve the above-described problems, and provides a sheet loading device, a post-processing device, and an image forming system that can stack sheets well on a discharge tray at a low stacking height without the device becoming larger and more costly or the discharge space on the discharge tray being narrowed.

Means for Solving the Problems

[0006] The sheet loading device in this invention comprises a discharge tray having a mounting surface on which sheets discharged from a discharge section in a predetermined discharge direction can be loaded, and a lifting tray installed above the discharge tray and configured to be raised and lowered according to the amount of sheets loaded, wherein the lifting tray has a pressing member installed at its bottom that can press down on the sheets loaded on the mounting surface of the discharge tray from above. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a sheet loading device, a post-processing device, and an image forming system that can load sheets onto a discharge tray at a low loading height without increasing the size and cost of the device or reducing the discharge space on the discharge tray. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram showing an image forming system according to an embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of an image forming apparatus. [Figure 3] This is a diagram showing the configuration of the post-processing device. [Figure 4] This is a diagram showing the configuration of a sheet loading device. [Figure 5] This diagram shows the transport mechanism for the pressing member installed in the sheet loading device. [Figure 6] This diagram shows the process when the folded sheet is discharged into the lower discharge tray. [Figure 7] This flowchart shows an example of the control process when the folded sheet is discharged into the lower discharge tray. [Figure 8] This is a block diagram showing a part of the control system in an image forming system. [Figure 9] This figure shows a transport mechanism for a pressing member installed in a sheet loading device, as an example of a modified example (1). [Figure 10]This diagram shows the operation when the folded sheet is discharged into the lower discharge tray, as an example of a modified example (modification 2). [Figure 11] This flowchart shows the control when the folded sheet is discharged into the lower discharge tray, as an example of modification 3. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments for carrying out this invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate.

[0010] First, Figure 1 will explain the overall configuration of the image forming system 100. In this embodiment, the image forming apparatus 1 is equipped with a long sheet feeding device 90 and a post-processing device 50 that can be detachably installed, and together with these devices 50 and 90, they constitute a single image forming system 100. In this embodiment, the post-processing device 50 is equipped with a distinctive sheet loading device 80 (see Figure 4, etc.), which will be explained in detail later.

[0011] The long sheet feeding device 90 is a feeding device for feeding sheets that are longer in length (size) in the transport direction compared to standard sheets of A3, A4 size, etc., such as sheets P (long sheets) with width x transport length of 297 mm x 900 mm or 297 mm x 1200 mm. The long sheet feeding device 90 in this embodiment is equipped with two paper feed cassettes 91 that can accommodate multiple long sheets P (cut paper). The long sheet P fed from the paper feed cassette 91 is then transported to the image forming apparatus 1 via the transport path K0. The long sheet P, on which the desired image has been formed in the image forming apparatus 1, is then discharged onto a discharge tray (either the upper tray 81, the lifting tray 82, or the lower discharge tray 83) via the post-processing device 50.

[0012] Next, the configuration and operation of the image forming apparatus 1 will be described in detail with reference to FIG. 2. As shown in FIG. 2, an intermediate transfer belt 8 is installed above the center of the image forming apparatus 1. Further, photoreceptor drums 2Y, 2M, 2C, and 2K (image forming units) corresponding to respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 8. Furthermore, the intermediate transfer belt 8 is pressed against a secondary transfer roller 15 (secondary transfer belt 16) below it to form a secondary transfer nip as an image forming unit.

[0013] As shown in FIG. 2, a charging unit 3, a developing unit 4, a cleaning unit 5, a charge removing unit, etc. are arranged around the photoreceptor drum 2K corresponding to black. Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process, charge removing process) is performed on the photoreceptor drum 2K, and a black image is formed on the surface of the photoreceptor drum 2K.

[0014] Note that the peripheries of the other three photoreceptor drums 2Y, 2M, and 2C are configured in substantially the same manner, and images corresponding to their respective toner colors are formed on the surfaces of the photoreceptor drums 2Y, 2M, and 2C. Hereinafter, the description of the image forming process on the other three photoreceptor drums 2Y, 2M, and 2C will be appropriately omitted, and only the image forming process corresponding to black will be described.

[0015] The photoreceptor drum 2K is rotationally driven counterclockwise in FIG. 2 by a main motor. Then, at the position of the charging unit 3, the surface of the photoreceptor drum 2K is uniformly charged (charging process). Thereafter, the surface of the photoreceptor drum 2K reaches the irradiation position of the laser light emitted from the exposure unit 7, and an electrostatic latent image corresponding to black is formed by exposure scanning in the width direction (the direction perpendicular to the paper surface in FIG. 2 and the main scanning direction) at this position (exposure process).

[0016] After that, the surface of the photoreceptor drum 2K reaches the position facing the developing unit 4, where the electrostatic latent image is developed and a black toner image is formed (development process). After that, the surface of the photoreceptor drum 2K reaches the position facing the intermediate transfer belt 8 and the primary transfer roller 6, and at this position, the toner image formed on the surface of the photoreceptor drum 2K is primarily transferred to the surface of the intermediate transfer belt 8 (primary transfer process). At this time, a small amount of untransferred toner remains on the photoreceptor drum 2K.

[0017] After that, the surface of the photoreceptor drum 2K reaches the position facing the cleaning unit 5, and at this position, the untransferred toner remaining on the photoreceptor drum 2K is collected into the cleaning unit 5 by the cleaning blade (cleaning process). Finally, the surface of the photoreceptor drum 2K reaches the position facing the charge removing unit, and at this position, the residual potential on the photoreceptor drum 2K is removed. Thus, a series of image forming processes performed on the photoreceptor drum 2K is completed.

[0018] Note that the above-described image forming process is also performed on the surfaces of the other photoreceptor drums 2Y, 2M, and 2C in the same manner as the black photoreceptor drum 2K. Then, the toner images of each color formed on the surfaces of the respective photoreceptor drums 2Y, 2M, 2C, and 2K are primarily transferred onto the intermediate transfer belt 8 in an overlapping manner. Thus, a color image is formed on the intermediate transfer belt 8.

[0019] After that, the intermediate transfer belt 8 onto which the toner images of each color are primarily transferred in an overlapping manner reaches the position facing the secondary transfer roller 15 (secondary transfer belt 16). At this position, the secondary transfer counter roller 9 sandwiches the intermediate transfer belt 8 and the secondary transfer belt 16 between the secondary transfer roller 15 to form a secondary transfer nip (image forming unit). Then, the four-color toner images formed on the intermediate transfer belt 8 are secondarily transferred onto a sheet P such as paper conveyed to this secondary transfer nip position (secondary transfer process). At this time, untransferred toner that has not been transferred to the sheet P remains on the intermediate transfer belt 8.

[0020] Subsequently, the intermediate transfer belt 8 reaches the intermediate transfer cleaning section. At this position, any untransferred toner or other deposits adhering to the surface of the intermediate transfer belt 8 are removed. Thus, the series of transfer processes performed on the intermediate transfer belt 8 are completed.

[0021] Referring to Figures 1 and 2, the sheet P that is transported to the secondary transfer nip (image forming section) is transported from the paper feed cassette 10 located below the image forming apparatus 1, via a transport path K1 in which paper feed rollers 11 and registration rollers 12 are arranged. More specifically, the paper feed cassette 10 contains multiple sheets P (normal sheets) of paper or other sheet-like media stacked together. When the paper feed roller 11 is driven to rotate counterclockwise as shown in Figure 2, the top sheet P is fed through the transport path K1 towards the rollers of the register roller 12.

[0022] The sheet P, transported to the register roller 12, temporarily stops at the position of the roller nip of the register roller 12, which has stopped its rotational drive. Then, in time with the color image on the intermediate transfer belt 8, the register roller 12 is driven to rotate again, and the sheet P is transported toward the secondary transfer nip (image forming section). In this way, the desired color image is transferred onto the sheet P.

[0023] Subsequently, the sheet P onto which the color image has been transferred at the secondary transfer nip is transported by the secondary transfer belt 16, separated from the secondary transfer belt 16, and then transported to the fixing section 19 by the transport belt 18. At this position, the color image transferred to the surface is fixed onto the sheet P by heat and pressure from the fixing belt and pressure rollers (this is the fixing process). Subsequently, the sheet P is discharged to the outside of the image forming apparatus 1 via the discharge transport path K2 by the paper discharge roller 25. Furthermore, the sheets P discharged from the image forming apparatus 1 are transported into the post-processing device 50, where post-processing such as punching, binding, and folding is performed. The post-processed sheets P (or sheet bundles PT) are then discharged into one of the three discharge trays 81-83 (see Figures 1, 3, 4, etc.). The configuration and operation of the post-processing device 50 will be explained in detail later. Thus, the series of image forming processes (image forming operations) in the image forming apparatus 1 are completed. Furthermore, when forming an image on a long sheet P fed from the long sheet feeding device 90 (see Figure 1), the same image formation process as described above will be performed, except for a different paper feeding path.

[0024] Referring to Figure 2, if the "double-sided printing mode," which prints on both sides of sheet P (front and back), is selected, the sheet P, after the fixing process on the front side is completed, is guided to the vertical transport path K4 by the operation of the first and second switching claws 35 and 36, instead of being ejected directly from the image forming apparatus 1 as described above when the "single-sided printing mode" is selected. Then, the sheet P guided to the vertical transport path K4 is guided to the inverted transport path K3 by the operation of the third switching claw 37. Then, the sheet P guided to the inverted transport path K3 has its transport direction reversed by the drive switching of the inverted roller 27 from forward rotation to reverse rotation, and is then guided to the horizontal transport path K5 by the operation of the third switching claw 37. Then, the sheet P guided to the horizontal transport path K5 is transported again toward the position of the secondary transfer nip (image forming section). Then, at the secondary transfer nip, an image is formed on the back surface of the sheet P by the same image forming process (image forming operation) as described earlier. After that, it undergoes a fixing process in the fixing unit 19 and is discharged from the image forming apparatus 1 via the discharge transport path K2. In other words, when "double-sided printing mode" is selected, the vertical transport path K4, the inverted transport path K3, and the horizontal transport path K5 will function as double-sided transport paths. The "single-sided print mode" and "double-sided print mode" are selected by the user using the operation display panel 39 (located on the exterior of the image forming apparatus 1).

[0025] The post-treatment device 50 will be described in detail below with reference to Figure 3. First, the sheet P discharged from the image forming apparatus 1 is fed into the post-processing device 50 by the inlet roller 71. At this time, the sheet P is detected by the sheet detection sensor 72. Then, if the user has previously selected "normal processing mode" on the operation display panel 39, the sheet P is either discharged from the discharge section A1 onto the upper tray 81 (first discharge tray) via the discharge roller pair 70 through the upper transport path K19 by switching the transport path by the switching claw 74, or discharged directly from the discharge section A2 onto the lifting tray 82 (second discharge tray) via the discharge roller pair 73 through the linear transport path K20. In this case, if the user has previously selected "punching" on the operation display panel 39, the sheet P will be punched by the punching processing unit 55 as it passes through the punching processing unit 55. Furthermore, the user can freely select whether to discharge the sheet P into the upper tray 81 or the lifting tray 82 by operating the operation display panel 39, or it can be automatically selected in advance based on certain control conditions. However, if the user has previously selected "sorting" on the operation display panel 39, the sheet P is discharged via the upper transport path K19 or the linear transport path K20 by the discharge roller pair 70, 73 onto the mounting surface of the upper tray 81 or the lifting tray 82. When the sheet P is discharged onto the upper tray 81 or the lifting tray 82 by the discharge roller pair 70, 73, the upper tray 81 and the lifting tray 82 (discharge trays with sorting function), which function as sorting processing units, move in the width direction in accordance with the timing of sorting the sheet P to perform sorting (sorting process).

[0026] In contrast, if the user has previously selected "binding processing mode" on the operation display panel 39 of the image forming apparatus 1, the sheet P is transported to the internal tray 76 via the binding processing transport path K21 by switching the transport path with the switching claw 74. Then, the sheet P (sheet bundle PT) loaded on the internal tray 76 is subjected to alignment processing in the transport direction and width direction.

[0027] In more detail, each time a sheet P (sheet bundle PT) is placed on the mounting surface of the internal tray 76, the tapping roller 75 positioned above it rotates around its axis of rotation from its retracted position to a position where it contacts the uppermost sheet P. The tapping roller 75 is driven to rotate counterclockwise as shown in Figure 3, thereby transporting the sheet P toward the end fence 78. As a result, the rear ends of multiple sheets P (sheet bundle PT) abut against the end fence 78, aligning the positions of the multiple sheets P (sheet bundle PT) in the transport direction. Furthermore, when the sheet bundle PT is aligned in the direction of transport in this manner, the side fences (jogger fences) installed at both ends in the width direction of the internal tray 76 move in the width direction (a direction perpendicular to the transport direction, and perpendicular to the plane of the paper in Figure 3) so as to sandwich the sheet P (sheet bundle PT) each time a sheet P is placed on the internal tray 76 (or after a desired number of sheets P have been loaded), thereby aligning the position of the sheet P (sheet bundle PT) in the width direction. Then, the rear end of the sheet bundle PT, which has been aligned in both the transport direction and the width direction, is bound by the binding device 85. Subsequently, the bound sheet bundle PT is moved diagonally upward along the mounting surface of the internal tray 76 by a conveyor belt (not shown), passes through the inclined conveyor path K22, and is then discharged into the lifting tray 82 by conveyance by the discharge roller pair 73. The lifting tray 82 is driven and controlled to move up and down according to the number of sheets (loading height) loaded, so that the height of the uppermost sheet P or sheet bundle PT remains constant.

[0028] Furthermore, if the "center folding mode" is selected in addition to the binding mode, the sheet bundle PT is transported from the internal tray 76 via the inclined transport path K22, and then, through the switching of the transport path by the switching guide member 65, it passes through the curved transport path along the curved transport guide member 66 towards the vertical transport path K23. In the vertical transport path K23, the sheet bundle PT is transported until the end of the sheets abuts against the end fence 86. Here, the end fence 86 is configured to be movable in the transport direction, and is adjusted to move so that the center of the sheet bundle PT in the transport direction is opposite the binding position of the saddle stitching device 79. Then, the sheet bundle PT is saddle-stitched in the center by the saddle stitching device 79. Subsequently, the end fence 86 is moved and adjusted so that the center of the sheet bundle PT in the transport direction faces the sheet folding blade 87. Then, with the center of the sheet bundle PT folded by the sheet folding blade 87 moving to the left in Figure 3, the folded portion is pressed against the sheet folding roller pair 88, and the center folding process is performed. After the center folding process, the sheet bundle PT is transported by the discharge roller pair 89 and discharged from the discharge section A3 onto the lower discharge tray 83, which serves as a discharge tray, and placed (stacked). Furthermore, even in binding mode or center folding mode, if the user has previously selected "punching" on the operation display panel 39, the sheet P will be punched by the punching processing unit 55 as it passes through the punching processing unit 55.

[0029] Furthermore, when selecting the "center-fold processing mode," it is also possible to set it so that at least one of the binding processes, either by the binding device 85 or the saddle-stitching device 79, is not performed. Furthermore, in such cases, instead of performing the folding process on a sheet bundle PT consisting of multiple sheets P, it is also possible to configure the system to perform the folding process on a single sheet P.

[0030] The sheet loading device 80, which is a characteristic feature of the post-processing device 50 (image forming system 100) in this embodiment, will be described in detail below. As explained earlier using Figure 3, the post-processing device 50 in this embodiment is equipped with a sheet loading device 80 which includes a lower discharge tray 83 as a discharge tray and a lifting tray 82.

[0031] The lower discharge tray 83, which serves as a discharge tray, is positioned at the bottom of the three discharge trays 81 to 83, and has a mounting surface (tray surface) on which sheets P (including sheet bundles PT) discharged from the discharge section A3 in a predetermined discharge direction (from right to left in Figure 3) can be stacked. As explained earlier, the sheets P (including the sheet bundle PT) discharged into the lower discharge tray 83 (discharge tray) are sheets P that have undergone a center-folding process, or sheets P that have undergone both center-folding and center-stitching processes. In other words, the sheets P discharged into the lower discharge tray 83 have been pressed and center-folded by at least the folding roller pair 88. Therefore, as shown in Figure 6, they are more prone to bulging vertically compared to sheets P that have not undergone center-folding (especially the folded portion).

[0032] Referring to Figures 3 and 4, the lifting tray 82 is installed above the lower discharge tray 83 (discharge tray) and is configured to move up and down in the direction of the white double arrows in Figure 3 according to the amount (loading height) of the sheets P (including the sheet bundle PT) that are loaded. For details, please refer to Figure 4. The lifting tray 82 has a holding portion 82a that extends vertically and is held vertically on the main body of the post-processing device 50 (sheet loading device 80). A pinion gear 82b and a motor (not shown) that rotates the pinion gear 82b are installed on the holding portion 82a of the lifting tray 82. This pinion gear 82b meshes with a rack gear 61 installed on the main body of the post-processing device 50 (sheet loading device 80). With this lifting mechanism configured, the motor of the pinion gear 82b is controlled to rotate in the forward or reverse direction by the control unit 150 (see Figure 8), causing the lifting tray 82 to move up and down.

[0033] Specifically, when sheets P (including a sheet bundle PT) are discharged onto the lifting tray 82, the motor of the pinion gear 82b is controlled to rotate in the forward or reverse direction according to the amount of sheets loaded (loading height) so that the height position of the uppermost of the multiple sheets P loaded (detected by a height detection sensor not shown) remains constant. In this embodiment, when sheets P (including sheet bundles PT) are discharged to the lower discharge tray 83, the lifting tray 82 is raised and lowered at a predetermined timing by the lifting mechanism described above, separately from the discharge to the lifting tray 82 (regardless of the amount of sheets loaded on the lifting tray 82). This will be explained later using Figure 6 and other figures.

[0034] Referring to Figures 4 and 6, the lifting tray 82 has a pressing member 60 installed at its bottom that can press down on the sheets P (including the sheet bundle PT) that are stacked on the mounting surface of the lower discharge tray 83 (discharge tray) from above. In particular, the pressing member 60 in this embodiment is configured to press the sheets P, which are stacked on the mounting surface of the lower discharge tray 83, from above, and to transport them in the discharge direction (the direction toward the left in Figures 4 and 6).

[0035] More specifically, a pressing member 60 is fixedly held (cantilevered) at the lower end of the holding portion 82a of the lifting tray 82, extending substantially parallel to the mounting surface of the lower discharge tray 83. Two roller members 60a and 60b (conveyor rollers) are rotatably installed at the bottom of the pressing member 60, spaced apart in the discharge direction. As shown in Figure 6(C), when the sheet P (at least a folded sheet) is discharged toward the lower discharge tray 83 by the discharge roller pair 89, the lifting tray 82, which was positioned above, descends under control by the control unit 150 (see Figure 8), pressing down on the sheet P from above. Therefore, compared to the case where the sheet P is not pressed by the pressing member 60, the sheet P that has been folded in the middle after being pressed by the folding roller pair 88 (see Figure 3) is further pressed by the pressing member 60. As a result, the upper part of the sheet P, separated by the fold, is less likely to bulge from the lower part, and the upper and lower parts, including the fold, are more likely to be in close contact, and the sheet P is loaded onto the lower discharge tray 83 in that state. Consequently, the sheet P discharged onto the lower discharge tray 83 is loaded well onto the lower discharge tray 83 at a low stacking height, making it easier for the user to remove the sheet P from the lower discharge tray 83. Furthermore, the number of sheets P that can be loaded to the full capacity of the lower discharge tray 83 can be increased. The pressing member 60, which functions in this way, is not configured to move up and down independently, but is installed on the lifting tray 82, which is originally installed as a discharge tray, and is configured to move up and down together with the lifting tray 82 using the lifting mechanism of the lifting tray 82. Therefore, compared to the case where an independent lifting and lowering pressing mechanism is provided, the sheet loading device 80 (post-processing device 50) is less likely to become larger and more expensive. Furthermore, since the pressing member 60 in this embodiment is not directly installed on the mounting surface of the lower discharge tray 83, the problem of reduced discharge space on the lower discharge tray 83 does not occur.

[0036] Here, as shown in Figures 6(C), (D), etc., the roller members 60a and 60b of the pressing member 60 in this embodiment are rotated in conjunction with the downward movement of the lifting tray 82 to transport the sheet P loaded on the mounting surface of the lower discharge tray 83 in the discharge direction. More specifically, as shown in Figures 4 and 5, the first roller member 60a of the pressing member 60 has a pulley installed at the end of its shaft, and a driven gear installed coaxially with the pulley around which the timing belt 111 is wound meshes with a drive gear installed coaxially with the pinion gear 82b. On the other hand, the pulley installed on the shaft of the first roller member 60a, together with the pulley installed on the shaft of the second roller member 60b, winds the timing belt 112 around it. With this configuration, as the lifting tray 82 descends, rotational force is transmitted from the pinion gear 82b to the first roller member 60a via the timing belt 111, and then from the first roller member 60a to the second roller member 60b via the timing belt 112. The first and second roller members 60a and 60b then rotate clockwise as shown in Figure 4(A), and the sheet P pressed by the first and second roller members 60a and 60b is transported in the discharge direction and strikes the end fence that stands upright on the downstream side of the lower discharge tray 83. Therefore, the sheets P discharged into the lower discharge tray 83 are stacked neatly in the discharge direction as well. As shown in Figure 4, a protective portion 60c is provided at the bottom of the downstream end (left side in Figure 4) of the pressing member 60, which protrudes downward, preventing the user from easily touching the rotating roller members 60a and 60b.

[0037] Furthermore, as shown in Figures 4(B) and 6(E), the roller members 60a and 60b of the pressing member 60 in this embodiment are not rotated when the lifting tray 82 is raised. More specifically, the drive gear, which is installed coaxially with the pinion gear 82b, is connected via a one-way clutch (not shown). When the pinion gear 82b rotates counterclockwise in Figure 4(A) (when the lifting tray 82 descends), the drive gear rotates counterclockwise together with the pinion gear 82, transmitting rotational force to the roller members 60a and 60b. In contrast, when the pinion gear 82b rotates clockwise in Figure 4(B) (when the lifting tray 82 rises), the drive gear rotates freely without rotating together with the pinion gear 82, and no rotational force is transmitted to the roller members 60a and 60b. This configuration prevents the problem of the sheets P loaded on the lower discharge tray 83 being reverse-conveniinated in the opposite direction of discharge by the roller members 60a and 60b when the lifting tray 82 rises after the pressing member 60 has finished pressing and conveying the sheets P.

[0038] Referring to Figure 6, in this embodiment, the pressing member 60 is controlled to press the sheets P loaded on the mounting surface of the lower discharge tray 83 when the stacking height of the sheets P discharged into the lower discharge tray 83 reaches its upper limit (when it is full). More specifically, as shown in Figure 6, the sheet loading device 80 (post-processing device 50) is equipped with fullness detection means 63 and 64 that detect whether the loading height of the sheets P discharged into the lower discharge tray 83 has reached its upper limit (whether it is full or not). The full-capacity detection means consists of a filler 63, a photosensor 64 (transmissive photosensor), and the like. The base of the filler 63 is rotatably held in the vicinity of the discharge roller pair 89 on the main body of the sheet loading device 80, and is positioned to rotate around its base when it comes into contact with the sheet P as it is discharged, without obstructing the transport (discharge) of the sheet P by the discharge roller pair 89. The rotation of the filler 63 is optically detected by the photosensor 64 installed near its base, and the number of sheets P discharged (number of sheets loaded onto the lower discharge tray 83) is counted. As shown in Figures 6(B) and (C), when the stacking height of the sheets P loaded on the lower discharge tray 83 reaches the upper limit (when it is full), the rotation of the filler 63 is restricted (it does not return to its original rotation position), and this state is detected by the photosensor 64, thereby confirming that it is full. In this embodiment, when the full capacity is detected by the full capacity detection means 63 and 64, the pressing member 60 descends together with the lifting tray 82, and the multiple sheets P stacked on the lower discharge tray 83 are pressed together by the pressing member 60. In this way, by performing the pressing operation by the pressing member 60 only when the tray is full, the lifting and lowering operation of the lifting tray 82 can be reduced compared to the case where the pressing operation by the pressing member 60 is performed every time a sheet P is discharged, thereby reducing the power consumed by the device.

[0039] Furthermore, in this embodiment, the pressing member 60 is configured to apply a variable pressing force to the sheets P placed on the mounting surface of the lower discharge tray 83, according to the number of sheets stacked in the lower discharge tray 83 (discharge tray). More specifically, when the fullness detection means 63 and 64 detect that the lower discharge tray 83 is full, if the number of sheets stacked is small, the bulge of each sheet P is assumed to be larger than when the number of sheets stacked is large. In order to eliminate this bulge (make them flat), the lowering position of the pressing member 60 (lifting tray 82) is set lower and the pressing force on those sheets P is increased.

[0040] The operation of the pressing member 60 when discharging the sheet P to the lower discharge tray 83 will be explained below using Figures 6(A) to (E). First, as shown in Figure 6(A), the lower discharge tray 83 is empty, and then, as shown in Figure 6(B), the lower discharge tray 83 is discharged and loaded with sheets P. However, when the full state is not detected by the fullness detection means 63 and 64, the lifting tray 82 (pressing member 60) is in a position sufficiently far above the lower discharge tray 83 (home position). Then, as shown in Figure 6(C), when the full-capacity detection means 63, 64 detect that the tray is full, the lifting tray 82 (pressing member 60) descends and presses against the sheet P on the lower discharge tray 83. Furthermore, as shown in Figure 6(D), the rotation of the roller members 60a, 60b of the pressing member 60 transports the sheet P on the lower discharge tray 83 in the discharge direction, and its position in the discharge direction is neatly determined when it abuts against the end fence. Then, when the pressing and transporting operation by the pressing member 60 is completed, the lifting tray 82 (pressing member 60) rises and returns to the home position, as shown in Figure 6(E).

[0041] The following describes an example of controlling the lifting tray 82 (pressing member 60) when discharging the sheet P to the lower discharge tray 83, using the flowchart in Figure 7. First, when a sheet P or a sheet bundle PT is discharged into the lower discharge tray 83, the fullness detection means 63 and 64 determine whether the tray is full (steps S1 and S2). As a result, if the full capacity is detected by the full capacity detection means 63 and 64, it is determined whether the number of stacked items (number of sheets stacked) is α1 or greater (step S3). If the number of stacked items is α1 or greater, the downward distance of the lifting tray 82 from the home position is set to K1 (step S4). Conversely, if the number of stacked items is not α1 or greater in step S3, it is determined whether the number of stacked items is α2 (<α1) or greater (step S5). If the number of stacked items is α2 or greater, the downward distance of the lifting tray 82 is set to K2 (>K1) (step S6). If the number of stacked items is not α2 or greater, the downward distance of the lifting tray 82 is set to K3 (>K2) (step S7). In the example in Figure 7, the downward distance of the lifting tray 82 is configured to be adjustable in three stages K1 to K3, but it is also possible to adjust it in more stages. Then, the lifting tray 82 is lowered to a descent distance set in step S4, S6, or S7 (step S8). In this way, the sheet P loaded on the lower discharge tray 83 is pressed by the pressing member 60, reducing the bulge of the sheet P. In addition, in conjunction with the pressing operation by the pressing member 60, a conveying operation is performed by the pressing member 60 to transport the sheet P in the discharge direction. The pressing by the pressing member 60 is performed for a predetermined time, and once that predetermined time has elapsed, the lifting tray 82 is raised towards the home position (step S9). Subsequently, it is determined whether the full-capacity detection means 63 and 64 still detect a full state (step S10). If the full-capacity detection remains, the destination of the sheet P is changed to a different discharge tray other than the lower discharge tray 83, or the discharge of the sheet P is stopped (step S11), and this flow is terminated. On the other hand, if the full-capacity detection is not detected in step S10, it is assumed that the discharge and loading of the sheet P to the lower discharge tray 83 is still possible, and the discharge of the sheet P to the lower discharge tray 83 is continued (step S12), and this flow is terminated.

[0042] Below, Figure 8 briefly explains a part of the control system in the image forming system 100. As shown in Figure 8, in the image forming system 100, the image forming apparatus 1 is communicated to the post-processing apparatus 50 and the long sheet feeding apparatus 90. The post-processing device 50 is equipped with a control unit 150 (computer) which has a CPU, a memory unit, and a communication interface with the image forming apparatus 1. The memory unit of the control unit 150 is composed of ROM, RAM, etc., and stores programs executed by the CPU. The control unit 150 is connected to a detection unit 160, which is represented by a sensor that determines the presence or absence of the sheet P and the position of the mechanism, and a drive unit 170, which is represented by a motor. The photosensor 64 of the full-capacity detection means described earlier belongs to the detection unit 160, and the lifting mechanism of the lifting tray 82 belongs to the drive unit 170. Then, the control unit 150 (CPU) operates the drive unit 170 according to the program stored in the memory unit, based on instructions sent from the image forming apparatus 1 and information on the status of the sheet P and each mechanism sent from the detection unit 160, so that the post-processing device 50 performs various processes on the sheet P transported from the image forming apparatus 1, such as binding, perforating, folding, and saddle stitching.

[0043] <Example 1> As shown in Figure 9, the sheet loading device 80 in Modification 1 differs from that in Figure 5, in which roller members 60a and 60b are used as the conveying mechanism for the pressing member 60, in which a belt member 60g is used as the conveying mechanism for the pressing member 60. The belt member 60g is rotated in conjunction with the downward movement of the lifting tray 82 to transport the sheet P loaded on the mounting surface of the lower discharge tray 83 in the discharge direction, and is configured not to rotate when the lifting tray 82 is rising. This belt member 60g is stretched and supported by two roller members 60e and 60f around which the timing belt 112 is wound. The rotational force of the pinion gear 82b (see Figure 4) is transmitted to the roller members 60e and 60f via the timing belts 111 and 112, causing it to travel in the direction of conveying the sheet P towards discharge. The rest of the conveying mechanism is almost the same as that shown in Figure 4. Furthermore, even when such a belt member 60g is used as a conveying mechanism, the sheets P discharged into the lower discharge tray 83 will be stacked neatly in the discharge direction as well.

[0044] <Modification 2> As shown in Figure 10, in the modified example 2, the sheet loading device 80 (post-processing device 50) differs from the one described in Figure 6 in that the pressing member 60 operates to press the sheet P each time a sheet P is loaded onto the mounting surface of the lower discharge tray 83 (discharge tray). Specifically, as shown in Figure 10(A), when a sheet P is discharged onto the lower discharge tray 83 from a state where no sheet P is placed on the lower discharge tray 83, as shown in Figure 10(B), the lifting tray 82 (pressing member 60) descends each time, pressing down on the sheet P on the lower discharge tray 83. Furthermore, as shown in Figure 10(D), the rotation of the roller members 60a and 60b of the pressing member 60 transports the pressed sheet P in the discharge direction, and its position in the discharge direction is neatly determined at the point where it abuts against the end fence on the lower discharge tray 83. When such pressing and transporting operation by the pressing member 60 is completed, as shown in Figure 10(E), the lifting tray 82 (pressing member 60) rises and returns to its home position. The series of operations described in Figures 10(B) to (E) are repeated each time a sheet P is discharged into the lower discharge tray 83. Furthermore, even when the lifting tray 82 (pressing member 60) is raised and lowered as in Modification 2, the device does not become larger or more expensive, nor does the discharge space on the discharge tray become narrower, and the sheets can be loaded onto the discharge tray well at a low loading height. In particular, in Modification 2, since the pressing operation by the pressing member 60 is performed each time a sheet P is discharged into the lower discharge tray 83, the effect of reducing the bulging of the sheet P loaded into the lower discharge tray 83 is more easily achieved.

[0045] <Variation 3> As shown in Figure 11, the sheet loading device 80 (post-processing device 50) in the modified example 3 is configured to either press the sheets P loaded on the mounting surface of the lower discharge tray 83 with the pressing member 60 when the stacking height of the sheets P discharged to the lower discharge tray 83 (discharge tray) reaches the upper limit, or to press the sheets P with the pressing member 60 each time a sheet P is loaded onto the mounting surface of the lower discharge tray 83. In other words, the user operates the operation display panel 39 (see Figure 2) to pre-select either a first control mode in which the pressing member 60 performs a pressing operation only when full capacity is detected, as explained earlier using Figure 6, or a second control mode in which the pressing member 60 performs a pressing operation each time a sheet P is discharged, as explained earlier using Figure 10. When the first control mode is selected, the pressing operation by the pressing member 60 as explained in Figure 6 is performed, and when the second control mode is selected, the pressing operation by the pressing member 60 as explained in Figure 10 is performed. For more details, an example of such control can be performed as shown in the flowchart of Figure 11, but it differs from the one explained in the flowchart of Figure 7 in that step S20 has been added. Specifically, when a sheet P or a sheet bundle PT is discharged into the lower discharge tray 83, it is determined whether the user has selected the first control mode (a mode in which a pressing operation is performed only when full is detected) (step S20). As a result, if the first control mode is selected, the control flow from step S2 onwards is performed, and if the first control mode is not selected (if the second control mode is selected), step S2 is skipped and the control flow from step S3 onwards is performed. Furthermore, even when the control is implemented as in Modification 3, the device does not become larger or more expensive, nor does the discharge space on the discharge tray become narrower, allowing the sheets to be loaded onto the discharge tray efficiently at a low loading height. In particular, Modification 3 allows the user to select one of two control modes according to their preference, resulting in a user-friendly device.

[0046] As described above, the sheet loading device 80 in this embodiment is equipped with a lower discharge tray 83 (discharge tray) which has a mounting surface on which sheets P discharged from the discharge section A3 in a predetermined discharge direction can be loaded. In addition, a lifting tray 82 configured to be able to move up and down according to the amount of sheets P loaded is installed above the lower discharge tray 83. The lifting tray 82 is equipped with a pressing member 60 at its bottom which can press down on the sheets P loaded on the mounting surface of the lower discharge tray 83 from above. This allows the sheets P to be loaded onto the lower discharge tray 83 at a low loading height without increasing the size or cost of the device, or reducing the discharge space on the lower discharge tray 83.

[0047] In this embodiment, the present invention was applied to an image forming system 100 equipped with a color image forming apparatus 1, but the present invention can naturally also be applied to an image forming system equipped with a monochrome image forming apparatus. Furthermore, although the present invention was applied to a sheet loading device 80 installed in the post-processing device 50 in this embodiment, the present invention can also be applied to sheet loading devices not installed in the post-processing device 50 (for example, a sheet loading device installed in the image forming apparatus 1), as long as they are equipped with a lifting tray above the discharge tray. Furthermore, although this embodiment applies the present invention to an image forming system 100 equipped with an electrophotographic image forming apparatus 1, the application of the present invention is not limited to this, and it can naturally be applied to image forming systems equipped with other types of image forming apparatuses (for example, inkjet image forming apparatuses or stencil printing apparatuses). Furthermore, in this embodiment, the present invention was applied to a sheet stacking device 80 configured to discharge sheets P (including sheet bundles PT) that have undergone a folding process into the lower discharge tray 83. However, the present invention can also be applied to a sheet stacking device configured to discharge sheets P (including sheet bundles PT) that have not undergone a folding process into the lower discharge tray 83. In that case, the application of the present invention becomes useful when bulging occurs in such sheets P (including sheet bundles PT). Furthermore, even in such cases, the same effects as those of this embodiment can be obtained.

[0048] Furthermore, in this embodiment, the post-processing device 50 is provided with a binding device 85, a punching device 55, a sorting device 73, and a center-folding device 86-88 as post-processing mechanisms. However, the post-processing mechanisms are not limited to these, and the post-processing mechanisms can be configured to perform other processes (for example, folding processes such as Z-folding, inward tri-folding, and outward tri-folding), or the post-processing mechanisms can be configured to consist of a different combination of the above-mentioned multiple processing devices. Furthermore, in this embodiment, the sheet loading device 80 (post-processing device 50) is provided with three discharge trays 81 to 83, but it is also possible to provide two or four or more discharge trays. Furthermore, although the image forming system 100 is equipped with a long sheet feeding device 90, the installation of the long sheet feeding device 90 can be omitted. Furthermore, even in such cases, the same effects as those of this embodiment can be obtained.

[0049] It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0050] In this specification, the term "sheet" is defined not only as a flat sheet of paper, but also as an envelope, as well as all other sheet-like recording media, such as coated paper, label paper, OHP sheets, etc. Furthermore, in this specification, the terms "discharge tray" and "lifting tray" are defined to include all objects on which a sheet can be placed, not limited to tray-shaped objects. [Explanation of Symbols]

[0051] 1. Image forming apparatus, 50 Post-processing equipment, 80-seat loading device, 60 Pressing member, 60a, 60b roller members, 60g belt component, 63 Filler (fullness detection means), 64. Photosensor (fullness detection means), 82 Height-adjustable trays, 83 Lower discharge tray (discharge tray), 100 image forming systems, P sheet, PT sheet bundle.

[0052] Furthermore, embodiments of the present invention can also be, for example, combinations of appendices 1 to 11 as follows. (Note 1) A discharge tray having a mounting surface on which sheets discharged from the discharge section in a predetermined discharge direction are placed so as to be stacked, A lifting tray is installed above the aforementioned discharge tray and is configured to be able to move up and down according to the amount of sheets loaded, Equipped with, The sheet loading device is characterized in that the lifting tray has a pressing member installed at its bottom that can press down on the sheet loaded on the aforementioned surface of the discharge tray from above. (Note 2) The sheet loading device according to Appendix 1, characterized in that the pressing member presses the sheets loaded on the aforementioned surface of the discharge tray from above and transports them in the discharge direction. (Note 3) The sheet loading device according to Appendix 2, characterized in that the pressing member comprises a roller member or a belt member that is rotationally driven in conjunction with the downward movement of the lifting tray to transport the sheets loaded on the aforementioned surface of the discharge tray in the discharge direction. (Note 4) The sheet loading device according to Appendix 3, characterized in that the roller member or the belt member is not rotationally driven when the lifting tray is raised. (Note 5) The sheet stacking device according to any one of the appendices 1 to 4, characterized in that the pressing force applied by the pressing member to the sheet stacked on the aforementioned surface of the discharge tray is varied according to the number of sheets stacked in the discharge tray. (Note 6) The sheet stacking device according to any one of the appendices 1 to 5, characterized in that the pressing member presses the sheets stacked on the aforementioned surface of the discharge tray when the stacking height of the sheets discharged into the discharge tray reaches the upper limit. (Note 7) The sheet loading device according to any one of the appendices 1 to 5, characterized in that the pressing member presses the sheet each time a sheet is loaded onto the loading surface of the discharge tray. (Note 8) A sheet stacking device according to any one of the appendices 1 to 5, characterized in that it is configured to select whether to press the sheets stacked on the aforementioned surface of the discharge tray with the pressing member when the stacking height of the sheets discharged to the discharge tray reaches the upper limit, or to press the sheets with the pressing member each time a sheet is stacked on the aforementioned surface of the discharge tray. (Note 9) The sheet loading device according to any one of the appendices 1 to 8, characterized in that the sheets discharged to the discharge tray are sheets that have been folded in the middle, or sheets that have been folded in the middle and saddle-stitched. (Note 10) A post-processing apparatus for performing post-processing on sheets discharged from an image forming apparatus, A post-processing device characterized by being equipped with a sheet loading device as described in any of Appendix 1 to Appendix 9. (Note 11) An image forming system characterized by comprising a post-processing device described in Appendix 10 and an image forming apparatus for forming an image on a sheet. [Prior art documents] [Patent Documents]

[0053] [Patent Document 1] Japanese Patent Publication No. 2012-6702

Claims

1. A discharge tray having a mounting surface on which sheets discharged from the discharge section in a predetermined discharge direction are placed so as to be stacked, A lifting tray is installed above the aforementioned discharge tray and is configured to be able to move up and down according to the amount of sheets loaded, Equipped with, The sheet loading device is characterized in that the lifting tray has a pressing member installed at its bottom that can press down on the sheet loaded on the aforementioned surface of the discharge tray from above.

2. The sheet loading device according to claim 1, characterized in that the pressing member presses the sheets loaded on the aforementioned surface of the discharge tray from above and transports them in the discharge direction.

3. The sheet loading device according to claim 2, characterized in that the pressing member comprises a roller member or a belt member that is rotationally driven in conjunction with the downward movement of the lifting tray to transport the sheets loaded on the aforementioned surface of the discharge tray in the discharge direction.

4. The sheet loading device according to claim 3, characterized in that the roller member or the belt member is not rotationally driven when the lifting tray is raised.

5. The sheet stacking device according to claim 1 or 2, characterized in that the pressing force applied by the pressing member to the sheets stacked on the aforementioned surface of the discharge tray is varied according to the number of sheets stacked in the discharge tray.

6. The sheet stacking device according to claim 1 or 2, characterized in that the pressing member presses the sheets stacked on the aforementioned surface of the discharge tray when the stacking height of the sheets discharged to the discharge tray reaches its upper limit.

7. The sheet loading device according to claim 1 or 2, characterized in that the pressing member presses the sheet each time a sheet is loaded onto the surface in front of the discharge tray.

8. The sheet stacking device according to claim 1 or 2, characterized in that it is configured to select whether to press the sheets stacked on the aforementioned surface of the discharge tray with the pressing member when the stacking height of the sheets discharged to the discharge tray reaches the upper limit, or to press the sheets with the pressing member each time a sheet is stacked on the aforementioned surface of the discharge tray.

9. The sheet stacking device according to claim 1 or 2, characterized in that the sheets discharged to the discharge tray are sheets that have been folded in the middle, or sheets that have been folded in the middle and saddle-stitched.

10. A post-processing apparatus for performing post-processing on sheets discharged from an image forming apparatus, A post-processing device characterized by comprising a sheet loading device according to claim 1 or claim 2.

11. An image forming system comprising a post-processing device according to claim 10 and an image forming apparatus for forming an image on a sheet.

Images