Sheet post-processing device and image forming system

Abstract

To provide a sheet post-processing device that can achieve high functionality through a low-cost configuration.SOLUTION: A sheet post-processing device 1 according to the present invention includes a post-processing main body 1M and an extension unit 1E. The extension unit 1E receives sheets that have passed through the post-processing main body 1M and is detachable from the post-processing main body 1M. The post-processing main body 1M includes a switching guide 13a that switches the sheet conveying direction between a first direction f1 that guides the sheet passing through the post-processing main body 1M to a second discharge tray 53 and a second direction f2 that guides the sheet to the extension unit 1E. The extension unit 1E includes a guide contact member 17f that contacts the switching guide 13a when attached to the post-processing main body 1M and changes the posture of the switching guide 13a to the second direction f2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a sheet post-processing device that performs post-processing on a sheet after image formation by an image forming apparatus, and an image forming system including the sheet post-processing device.

Background Art

[0002] A sheet post-processing device that performs post-processing such as stapling or folding on a sheet after image formation by an image forming apparatus such as a copier or a printer is known. Such a sheet post-processing device may be configured such that add-on units each having various functions can be detachably attached.

[0003] For example, a conventional paper processing device disclosed in Patent Document 1 is mounted and fixed on the upper part of a paper post-processing device main body. The paper processing device has a plurality of discharge trays in the vertical direction and is added to the paper post-processing device as a so-called mailbox. Thereby, the paper processing device can impart the function of a mailbox to the paper post-processing device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the prior art has a problem in that paper introduction means for guiding paper from the paper post-processing device main body into the paper processing device is provided on the paper processing device side. As a result, it is necessary to provide paper introduction means for all of the various add-on units attached to the paper post-processing device such as the paper processing device, and there is a concern about an increase in the cost of the add-on unit.

[0006] The present invention has been made in view of the above points, and an object thereof is to provide a sheet post-processing apparatus and an image forming system capable of achieving high functionality with a configuration that enables cost reduction.

Means for Solving the Problems

[0007] To solve the above problems, the sheet post-processing apparatus of the present invention includes a post-processing main body unit and an additional unit. The post-processing main body unit performs a predetermined post-processing on a sheet and discharges the sheet to a main body discharge tray. The additional unit is detachable from the post-processing main body unit and allows the sheet that has passed through the post-processing main body unit to enter. The post-processing main body unit includes a switching guide that switches the conveyance direction of the sheet between a first direction that guides the sheet passing through the post-processing main body unit to the main body discharge tray and a second direction that guides the sheet to the additional unit. The additional unit includes a guide contact member that contacts the switching guide when attached to the post-processing main body unit and changes the posture of the switching guide in the second direction.

Effects of the Invention

[0008] According to the configuration of the present invention, a switching guide for guiding a sheet from the post-processing main body unit to the additional unit is provided in the post-processing main body unit. As a result, it is not necessary to provide a switching guide for all of the various additional units attached to the post-processing main body unit, and cost reduction of the additional unit can be achieved. Therefore, high functionality of the sheet post-processing apparatus can be achieved with a configuration that enables cost reduction.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following content.

[0011] FIG. 1 is a front view of an image forming system 301 according to an embodiment. As shown in FIG. 1, the image forming system 301 includes an image forming apparatus 201 and a sheet post-processing apparatus 1.

[0012] The image forming apparatus 201 has, for example, an electrophotographic printing mechanism and is a so-called multifunction device corresponding to monochrome that has functions such as printing, scanning (image reading), and facsimile transmission. Note that the image forming apparatus 201 may be, for example, a device such as a copying machine or a printer, and may also be a color-compatible device.

[0013] The image forming apparatus 201 includes an image forming unit, a transfer unit, and a fixing unit (none of which are shown). In the image forming unit, toner is supplied to and developed on the electrostatic latent image of the original image formed on the surface of the photosensitive drum by laser light to form a toner image of the original image. The transfer unit transfers the toner image formed on the surface of the photosensitive drum to a sheet. The fixing unit heats and presses the sheet onto which the toner image has been transferred to fix the toner image to the sheet. In this way, the image forming apparatus 201 forms (prints) an image on the sheet. Then, the image forming apparatus 201 conveys the sheet after image formation to the sheet post-processing apparatus 1.

[0014] The sheet post-processing apparatus 1 is detachably connected to the side surface of the image forming apparatus 201. Note that the sheet post-processing apparatus 1 can be similarly connected to devices such as a multifunction machine, a copier, a printer, etc. in addition to the multifunction machine. The sheet post-processing apparatus 1 performs predetermined post-processing on the sheet after image formation (printing) in the image forming apparatus 201.

[0015] As shown in FIG. 1, the sheet post-processing apparatus 1 includes a post-processing main body unit 1M and an additional unit 1E. The post-processing main body unit 1M performs predetermined post-processing on the sheet and discharges the sheet to the first discharge tray 33, the second discharge tray (main body discharge tray) 53, or the third discharge tray 73, which will be described later. The additional unit 1E is detachable from the post-processing main body unit 1M, and the sheet that has passed through the post-processing main body unit 1M enters it.

[0016] FIG. 2 is a schematic cross-sectional front view of the post-processing main body unit 1M of the sheet post-processing apparatus 1 in FIG. 1. As shown in FIG. 2, the post-processing main body unit 1M includes a sheet loading path 2, a first sheet discharge unit 3, a first sheet discharge path 4, a second sheet discharge unit 5, a second sheet discharge path 6, a third sheet discharge unit 7, a third sheet discharge path 8, a post-processing unit 11, and a post-processing control unit 12.

[0017] The sheet inlet path 2 has a sheet inlet 2e. The sheet inlet 2e is provided on the side surface of the sheet post-processing device 1 facing the image forming device 201 and is open. The sheet conveyed from the image forming device 201 toward the sheet post-processing device 1 is carried into the interior of the sheet post-processing device 1 through the sheet inlet 2e and the sheet inlet path 2.

[0018] The sheet inlet path 2 extends in a substantially horizontal direction in a direction away from the image forming device 201 (the left direction in FIG. 2) from the sheet inlet 2e to a sheet folding portion 113 described later. The sheet inlet path 2 has a first branch portion 2a and a second branch portion 2b arranged in order from the upstream side (the sheet inlet 2e side) in the sheet conveyance direction.

[0019] The first branch portion 2a switches the conveyance direction of the sheet conveyed from the sheet inlet 2e side to the downstream side to a direction leading to the first sheet discharge portion 3 and the second sheet discharge portion 5 and a direction leading to the third sheet discharge portion 7. The second branch portion 2b switches the conveyance direction of the sheet conveyed from the sheet inlet 2e side to the downstream side to a direction leading to the first sheet discharge portion 3 and a direction leading to the second sheet discharge portion 5.

[0020] The first sheet discharge portion 3 is provided on the side surface 1a opposite to the side surface of the sheet post-processing device 1 facing the image forming device 201. The first sheet discharge portion 3 has a first discharge port 31, a first discharge roller pair 32, and a first discharge tray 33.

[0021] The first discharge port 31 is located at the downstream end in the sheet discharge direction of the first sheet discharge path 4. The first discharge roller pair 32 is arranged at the first discharge port 31. The first discharge tray 33 is located on the downstream side in the sheet discharge direction of the first discharge port 31. The sheet conveyed through the first sheet discharge path 4 and reaching the first discharge port 31 is discharged onto the first discharge tray 33 through the first discharge port 31 by the first discharge roller pair 32.

[0022] The first sheet discharge path 4 is continuous from the downstream end of the sheet conveyance path 2 in the sheet discharge direction, and extends substantially horizontally in a direction away from the image forming apparatus 201 (the left direction in FIG. 2) to the first sheet discharge unit 3.

[0023] The second sheet discharge unit 5 is provided on the side surface 1a of the sheet post-processing apparatus 1, above the first sheet discharge unit 3. The second sheet discharge unit 5 includes a second discharge port 51, a second discharge roller pair 52, and a second discharge tray (main body discharge tray) 53.

[0024] The second discharge port 51 is located at the downstream end of the second sheet discharge path 6 in the sheet discharge direction. The second discharge roller pair 52 is disposed at the second discharge port 51. The second discharge tray 53 is located on the downstream side of the second discharge port 51 in the sheet discharge direction. The sheet conveyed through the second sheet discharge path 6 and reaching the second discharge port 51 is discharged onto the second discharge tray 53 through the second discharge port 51 by the second discharge roller pair 52.

[0025] The second sheet discharge path 6 branches from a second branch portion 2b located in the downstream part of the sheet conveyance path 2 in the sheet discharge direction, and extends laterally and upward in a direction away from the image forming apparatus 201 (the left direction in FIG. 2) to the second sheet discharge unit 5.

[0026] The third sheet discharge unit 7 is provided on the side surface 1a of the sheet post-processing apparatus 1, below the first sheet discharge unit 3. In other words, the third sheet discharge unit 7 is disposed near the bottom of the sheet post-processing apparatus 1. The third sheet discharge unit 7 includes a third discharge port 71, a third discharge roller pair 72, and a third discharge tray 73.

[0027] The third discharge port 71 is located at the downstream end of the third sheet discharge path 8 in the sheet discharge direction. The third discharge roller pair 72 is disposed at the third discharge port 71. The third discharge tray 73 is located on the downstream side of the third discharge port 71 in the sheet discharge direction. The sheet conveyed through the third sheet discharge path 8 and reaching the third discharge port 71 is discharged onto the third discharge tray 73 through the third discharge port 71 by the third discharge roller pair 72.

[0028] The third sheet discharge path 8 branches off from a first branch portion 2a located downstream in the sheet discharge direction of the sheet carry-in path 2, and extends downward to the third sheet discharge portion 7.

[0029] The post-processing unit 11 performs predetermined processing on the sheets that are image-formed by the image forming apparatus 201 and carried into the sheet post-processing apparatus 1. The post-processing unit 11 includes a punching unit 111, a stapling unit 112, a sheet folding unit 113, and a binding unit 114.

[0030] The punching unit 111 is disposed immediately downstream of the sheet carry-in port 2e in the sheet carry-in path 2. The punching unit 111 can perform a punching process on the sheet conveyed on the sheet carry-in path 2 to form punch holes.

[0031] The stapling unit 112 is disposed below the first sheet discharge path 4 and near the first sheet discharge portion 3. The stapling unit 112 can perform a stapling process (binding process) on a stack of a plurality of sheets to bind the stack of sheets.

[0032] The sheet folding unit 113 is disposed downstream of the punching unit 111 and upstream of the stapling unit 112 with respect to the sheet conveyance direction of the sheet carry-in path 2. The sheet folding unit 113 can perform a folding process on a single sheet to form a fold line.

[0033] The binding unit 114 is disposed near the third sheet discharge portion 7 at the downstream portion in the sheet discharge direction of the third sheet discharge path 8. The binding unit 114 can perform a center folding process and a center binding process of folding and binding the substantially central portion in the sheet discharge direction on a stack of a plurality of sheets to form a booklet.

[0034] The post-processing control unit 12 includes a CPU, an image processing unit, a storage unit, and other electronic circuits and components (all not shown). The post-processing control unit 12 is communicably connected to an image formation control unit (not shown) of the image forming apparatus 201. The post-processing control unit 12 receives a command from the image formation control unit, and based on a program and data for control stored in the storage unit using the CPU, controls the operations of the respective components provided in the sheet post-processing apparatus 1 to perform processing related to the functions of the sheet post-processing apparatus 1. Each of the sheet conveyance path 2, the first sheet discharge unit 3, the first sheet discharge path 4, the second sheet discharge unit 5, the second sheet discharge path 6, the third sheet discharge unit 7, the third sheet discharge path 8, and the post-processing unit 11 receives an individual command from the post-processing control unit 12 and performs post-processing on the sheet in conjunction with each other. Note that the functions of the post-processing control unit 12 may be provided in the image formation control unit of the image forming apparatus 201.

[0035] FIG. 3 is a schematic cross-sectional front view of the expansion unit 1E of the sheet post-processing apparatus 1 in FIG. 1. FIG. 4 is an external perspective view of the expansion unit 1E in FIG. 3. As shown in FIG. 1, the expansion unit 1E is disposed above the post-processing main body 1M. As shown in FIG. 3, the post-processing main body 1M includes a conveyance switching unit 13. As shown in FIGS. 3 and 4, the expansion unit 1E includes a sheet conveyance path 14, a sheet sorting unit 15, a sheet discharge unit 16, and a drive unit 17.

[0036] The conveyance switching unit 13 is at the upper end of the post-processing main body 1M and is disposed on the second sheet discharge path 6. The conveyance switching unit 13 is located on the upstream side in the sheet conveyance direction of the second sheet discharge path 6 with respect to the second discharge port 51.

[0037] In the conveyance switching unit 13, a switching guide 13a is arranged. The switching guide 13a is disposed at a first position for conveying a sheet conveyed from the second branch portion 2b side toward the downstream side in the sheet conveyance direction on the second sheet discharge path 6 in a first direction f1 for guiding the sheet to the second sheet discharge unit 5, and a second position for conveying the sheet in a second direction f2 for guiding the sheet to the additional unit 1E. In other words, the switching guide 13a switches the conveyance direction of the sheet passing through the post-processing main body portion 1M between a first direction f1 for guiding the sheet to the second discharge tray (main body discharge tray) 53 and a second direction f2 for guiding the sheet to the additional unit 1E.

[0038] The sheet conveyance path 14 extends vertically within the additional unit 1E. When the additional unit 1E is attached to the post-processing main body portion 1M, the sheet conveyance path 14 is connected to the conveyance switching unit 13. The sheet conveyance path 14 extends vertically from the conveyance switching unit 13 to the upper end portion of the additional unit 1E.

[0039] The sheet sorting unit 15 is arranged on the sheet conveyance path 14 on the downstream side in the sheet conveyance direction with respect to the conveyance switching unit 13. A plurality of sorting guides 15a are arranged in the sheet sorting unit 15. The plurality of sorting guides 15a are arranged in a quantity corresponding to the quantity of the sheet discharge trays 16a of the sheet discharge unit 16 described later. In the present embodiment, six sorting guides 15a are arranged corresponding to the second-stage sheet discharge tray 16a from the top to the lowermost sheet discharge tray 16a. Note that, for the uppermost sheet discharge tray 16a, the sheets that have not been sorted by the sorting guide 15a up to the uppermost end of the sheet conveyance path 14 are discharged.

[0040] Each of the six sorting guides 15a sorts a sheet conveyed from the conveyance switching unit 13 side toward the downstream side in the sheet conveyance direction on the sheet conveyance path 14 to the sheet discharge tray 16a located on the side of the sorting guide 15a. Note that FIG. 3 shows a state in which the sheet entering the additional unit 1E is sorted to the lowermost sheet discharge tray 16a.

[0041] The sheet discharge unit 16 is arranged on the downstream side in the sheet conveyance direction with respect to the sheet sorting unit 15. The sheet discharge unit 16 is located above the side surface 1a of the post-processing main body unit 1M. The sheet discharge unit 16 has a plurality of stages of sheet discharge trays 16a. In the present embodiment, the sheet discharge unit 16 has seven sheet discharge trays 16a.

[0042] The sheet that has passed through the post-processing main body unit 1M and entered the additional unit 1E is sorted by the sheet sorting unit 15 on the sheet conveyance path 14 and discharged to any one of the seven sheet discharge trays 16a. The sheet discharge tray 16a is one of the final discharge locations for the sheets that have been post-processed by the sheet post-processing apparatus 1.

[0043] The drive unit 17 is arranged at the end in the sheet width direction (the depth direction of the paper surface in FIG. 3) orthogonal to the sheet conveyance direction of the sheet conveyance path 14. The drive unit 17 includes a pulley 17a, a belt 17b, a pressing piece 17c, a plurality of sorting swing pieces 17d, a switching swing piece 17e, and a guide contact member 17f.

[0044] The pulley 17a is arranged at two locations, the upper part and the lower part of the additional unit 1E. Each of the two pulleys 17a is supported by a shaft portion 17ax extending in the sheet width direction and is rotatable around the axis of the shaft portion 17ax. One of the two pulleys 17a is connected to a motor (not shown) and is rotated by the motor. The operation of the motor is controlled by the post-processing control unit 12 or the image formation control unit of the image forming apparatus 201.

[0045] The belt 17b is formed in an annular shape and wound around the two pulleys 17a. That is, the belt 17b forms an oval shape extending in the vertical direction. The belt 17b rotates along the outer circumferences of the two pulleys 17a by a motor connected to the pulley 17a.

[0046] The pressing piece 17c is fixed to the outer peripheral portion of the belt 17b and protrudes outward from the belt 17b. The pressing piece 17c moves along the orbit of the belt 17b as the belt 17b rotates. As it moves, the pressing piece 17c comes into contact with the sorting swing piece 17d and the switching swing piece 17e respectively, and displaces the sorting swing piece 17d and the switching swing piece 17e.

[0047] Each of the plurality of sorting swing pieces 17d is arranged on the orbit of the pressing piece 17c that moves as the belt 17b rotates. In this embodiment, six sorting swing pieces 17d are arranged corresponding to the number of the sorting guides 15a. That is, six pairs of sorting swing pieces 17d and sorting guides 15a are arranged. Each of the six sorting swing pieces 17d is juxtaposed in the vertical direction along the sheet conveyance path 14 corresponding to each of the six sorting guides 15a. The paired sorting swing piece 17d and sorting guide 15a are both supported by a shaft portion 17dx extending in the sheet width direction and are swingable (rotatable) about the axis of the shaft portion 17dx.

[0048] The sorting swing piece 17d is biased by the action of a spring (not shown) or gravity so that the sorting guide 15a is arranged in a posture where the sheet is conveyed vertically upward along the sheet conveyance path 14. Then, when sorting the sheet to the corresponding sheet discharge tray 16a, the pressing piece 17c moving together with the belt 17b contacts the sorting swing piece 17d, and the sorting swing piece 17d is displaced against the biasing force so that the sorting guide 15a is arranged in a posture for sorting the sheet to the sheet discharge tray 16a.

[0049] The switching swing piece 17e is arranged below the lower pulley 17a. The switching swing piece 17e is arranged on the orbit of the pressing piece 17c that moves as the belt 17b rotates. The switching swing piece 17e is supported by a shaft portion 17ex extending in the sheet width direction and is rotatable about the axis of the shaft portion 17ex. The switching swing piece 17e has a connecting portion 17ec to which the guide contact member 17f is rotatably connected on the outer side in the radial direction of the shaft portion 17ex.

[0050] The switching swing piece 17e is biased by a spring (not shown) so that the guide contact member 17f connected to the connecting portion 17ec is disposed at the upper position. When the additional unit 1E is mounted on the post-treatment main body 1M, when discharging the sheet passing through the inside of the post-treatment main body 1M to the second sheet discharge portion 5, the pressing piece 17c moving together with the belt 17b contacts the switching swing piece 17e, whereby the switching swing piece 17e is displaced against the biasing force so that the guide contact member 17f is disposed at the lower position.

[0051] The guide contact member 17f is disposed below the switching swing piece 17e and at the lower end portion of the additional unit 1E. The guide contact member 17f is formed in a rod shape extending substantially in the vertical direction, and is connected to the connecting portion 17ec of the switching swing piece 17e at the upper end portion. The guide contact member 17f is disposed at the upper position and the lower position located below the upper position by the swinging of the switching swing piece 17e around the axis of the shaft portion 17ex.

[0052] The lower portion of the guide contact member 17f projects below the bottom plate 1Eb through the hole portion 1Eh provided in the bottom plate 1Eb of the additional unit 1E. The lower end portion of the guide contact member 17f contacts the switching guide 13a when the additional unit 1E is mounted on the post-treatment main body 1M of the additional unit 1E.

[0053] Subsequently, the movement of the switching guide 13a will be described with reference to FIGS. 5 to 10. FIGS. 5 and 6 are a partial perspective view of the periphery of the guide contact member 17f of the additional unit 1E in FIG. 4 and a cross-sectional front view of the periphery of the switching guide 13a of the sheet post-treatment apparatus 1 in FIG. 3 when discharging the sheet by the additional unit 1E. FIG. 7 is a partial perspective view of the periphery of the switching guide 13a in FIG. 6. FIGS. 8 and 9 are a partial perspective view of the periphery of the guide contact member 17f of the additional unit 1E in FIG. 4 and a cross-sectional front view of the periphery of the switching guide 13a of the sheet post-treatment apparatus 1 in FIG. 3 when discharging the sheet by the post-treatment main body 1M. FIG. 10 is a partial perspective view of the periphery of the switching guide 13a in FIG. 9.

[0054] Figs. 5, 6, and 7 show a state in which the additional unit 1E is attached to the post-treatment main body 1M, and a state in which a sheet passing through the post-treatment main body 1M is guided to the additional unit 1E. In Fig. 5, the entire post-treatment main body 1M is shown, and in Figs. 6 and 7, some of the components of the post-treatment main body 1M are omitted from the description.

[0055] When guiding the sheet passing through the post-treatment main body 1M to the additional unit 1E, as shown in Figs. 5 and 7, the pressing piece 17c fixed to the belt 17b is separated from the switching swing piece 17e. For example, as shown in Fig. 5, the pressing piece 17c contacts the lowermost distribution swing piece 17d, and the distribution guide 15a is displaced in a posture to distribute the sheet to the lowermost sheet discharge tray 16a so that the distribution swing piece 17d is arranged (see Figs. 3 and 4).

[0056] When the pressing piece 17c is separated from the switching swing piece 17e, the switching swing piece 17e rotates clockwise in Fig. 5 by the biasing force of a spring (not shown) to pull up the guide contact member 17f. As a result, the guide contact member 17f is arranged at the upper position.

[0057] In a state where the additional unit 1E is attached to the post-treatment main body 1M, the lower end portion of the guide contact member 17f contacts the switching guide 13a of the conveyance switching unit 13. Here, the switching guide 13a is biased by the action of a spring (not shown) or gravity so as to be arranged at a second position for guiding the sheet passing through the post-treatment main body 1M to the additional unit 1E.

[0058] When the guide contact member 17f is arranged at the upper position, a force for pushing down the switching guide 13a by the guide contact member 17f does not occur. As a result, as shown in Figs. 6 and 7, the switching guide 13a is biased by the action of a spring or gravity and is arranged at the second position so as to convey in the second direction f2 for guiding the sheet passing through the post-treatment main body 1M to the additional unit 1E.

[0059] Figures 8, 9, and 10 show a state in which the additional unit 1E is attached to the post-treatment main body 1M, and a state in which a sheet passing through the post-treatment main body 1M is guided to the second sheet discharge unit (main body discharge tray) 5. In FIG. 8, the entire post-treatment main body 1M is shown, and in FIGS. 9 and 10, some components of the post-treatment main body 1M are omitted.

[0060] When guiding the sheet passing through the post-treatment main body 1M to the second sheet discharge unit 5, as shown in FIGS. 8 and 10, the pressing piece 17c fixed to the belt 17b is in contact with the switching swing piece 17e. When the pressing piece 17c is in contact with the switching swing piece 17e, the switching swing piece 17e receives the force from the contacting pressing piece 17c and rotates counterclockwise in FIG. 5 to push down the guide contact member 17f. As a result, the guide contact member 17f is disposed at the lower position.

[0061] When the guide contact member 17f is disposed at the lower position, a force is generated to push down the switching guide 13a by the guide contact member 17f. As a result, as shown in FIGS. 9 and 10, the switching guide 13a is disposed at the first position so as to convey the sheet passing through the post-treatment main body 1M in the first direction f1 that guides the sheet to the second discharge tray 53 against the biasing force due to the action of the spring or gravity.

[0062] According to the above configuration, the post-treatment main body 1M of the sheet post-treatment device 1 is provided with a switching guide 13a for guiding the sheet from the post-treatment main body 1M to the additional unit 1E. As a result, it is not necessary to provide the switching guide 13a for all of the various additional units 1E attached to the post-treatment main body 1M, and the cost of the additional unit 1E can be reduced. Therefore, with the configuration in which the cost is reduced, it is possible to enhance the functionality of the sheet post-treatment device 1.

[0063] Further, as shown in FIGS. 11 and 12, the post-treatment main body 1M includes a cover member 18. FIG. 11 is a front cross-sectional view around the switching guide 13a of the sheet post-treatment device 1 with the cover member 18 attached. FIG. 12 is a partial perspective view around the switching guide 13a of FIG. 11.

[0064] The cover member 18 is disposed at the upper end of the post-treatment main body 1M. The cover member 18 is formed in a flat plate shape extending in the horizontal direction and covers the upper end of the post-treatment main body 1M. The cover member 18 is detachable from the mounting location of the additional unit 1E when the additional unit 1E is not mounted at the upper end of the post-treatment main body 1M. The cover member 18 has a guide restricting portion 18a.

[0065] The guide restricting portion 18a is disposed on the lower surface of the cover member 18 and is formed as a protruding portion protruding downward. The guide restricting portion 18a is disposed at the same position as the guide contact member 17f when the additional unit 1E is mounted on the post-treatment main body 1M. Specifically, the guide restricting portion 18a is disposed at the same position (see FIGS. 8 and 10) as the guide contact member 17f in a state where it is pushed down by the pressing piece 17c and disposed at the lower position.

[0066] As shown in FIG. 12, when the cover member 18 is mounted on the post-treatment main body 1M, the guide restricting portion 18a contacts the switching guide 13a. Thereby, as shown in FIGS. 11 and 12, the switching guide 13a is disposed at the first position so as to convey the sheet passing through the post-treatment main body 1M in the first direction f1 leading to the second discharge tray 53 against the biasing force by the spring or gravity. That is, the guide restricting portion 18a changes the posture of the switching guide 13a in the first direction in which the sheet is guided to the second discharge tray 53.

[0067] According to the above configuration, by disposing the cover member 18 that covers the upper end of the post-treatment main body 1M on the post-treatment main body 1M, the switching guide 13a can be automatically disposed at the first position that conveys the sheet in the first direction f1 leading to the second discharge tray 53. That is, there is no need to provide a component for driving the switching guide 13a, and the cost of the post-treatment main body 1M can be reduced. Therefore, with the configuration in which the cost is reduced, it is possible to enhance the functionality of the sheet post-treatment apparatus 1.

[0068] Returning to FIGS. 3 and 4, the additional unit 1E includes a conveyance guide 19. The conveyance guide 19 is disposed on a side surface of the additional unit 1E facing the image forming apparatus 201, which is opposite to the side surface where the sheet discharge unit 16 is disposed. The conveyance guide 19 is an exterior member that covers the side surface of the additional unit 1E and is formed in a flat plate shape extending in the vertical direction and the front-rear direction. The conveyance guide 19 guides the sheet conveyed through the sheet conveyance path 14 on its inner surface.

[0069] As shown in FIGS. 3 and 6, a part of the lower portion of the conveyance guide 19 is inserted into the post-processing main body portion 1M when the additional unit 1E is attached to the post-processing main body portion 1M. And when the additional unit 1E is attached to the post-processing main body portion 1M, the conveyance guide 19 faces the switching guide 13a with a sheet conveyance path of the sheet conveyed in the second direction f2 therebetween.

[0070] According to the above configuration, it is not necessary to provide a conveyance guide within the post-processing main body portion 1M with respect to the conveyance path of the sheet conveyed in the second direction f2 in the conveyance switching unit 13. Thereby, it becomes possible to reduce the cost of the post-processing main body portion 1M.

[0071] Also, the conveyance guide 19 has a fixed guide portion 19a and a movable guide portion 19b. The fixed guide portion 19a and the movable guide portion 19b are juxtaposed continuously in the vertical direction.

[0072] The fixed guide portion 19a is disposed at the lower portion of the additional unit 1E and is located below the movable guide portion 19b. The fixed guide portion 19a is inserted into the post-processing main body portion 1M when the additional unit 1E is attached to the post-processing main body portion 1M. The fixed guide portion 19a extends from within the post-processing main body portion 1M across into the additional unit 1E.

[0073] According to the above configuration, the sheet heading toward the additional unit 1E can be smoothly conveyed from within the post-processing main body portion 1M to within the additional unit 1E. Therefore, it is possible to suppress the occurrence of problems such as paper jams at the connection portion between the post-processing main body portion 1M and the additional unit 1E.

[0074] The movable guide part 19b is arranged on the upper part of the additional unit 1E and is located above the fixed guide part 19a. As shown in FIG. 3, the movable guide part 19b is supported by a shaft part 19bx extending in the sheet width direction arranged at the upper end part, and is rotatable around the axis of the shaft part 19bx. The movable guide part 19b can be opened and closed by rotating around the axis of the shaft part 19bx, and the sheet conveyance path 14 in the additional unit 1E can be exposed.

[0075] According to the above configuration, by being able to expose the sheet conveyance path 14, it becomes possible to easily access the sheet conveyance path 14 and the sheet sorting part 15. Therefore, maintenance of the sheet conveyance path in the additional unit 1E, dealing with malfunctions, etc. can be easily carried out.

[0076] Further, the additional unit 1E has a plurality of stages of sheet discharge trays 16a for sorting and discharging the sheets that have entered from the post-processing main body part 1M. As described above, in this embodiment, the additional unit 1E has seven sheet discharge trays 16a. That is, the additional unit 1E of this embodiment is a unit having a function also called a mailbox having a plurality of stages of sheet discharge trays (bins) arranged side by side in the vertical direction. Therefore, according to this embodiment, in the additional unit 1E having the function of a mailbox, it is possible to reduce the number of parts and achieve cost reduction.

[0077] As described above, the embodiments of the present invention have been described, but the scope of the present invention is not limited to this, and various modifications can be made and implemented without departing from the gist of the invention.

[0078] For example, in the above embodiment, the additional unit 1E is a unit having the function of a mailbox having a plurality of stages of sheet discharge trays (bins), but it is not necessarily limited to such a device. The additional unit may be a unit having other functions different from a mailbox.

Industrial Applicability

[0079] The present invention can be used in a sheet post-processing apparatus of an image forming apparatus.

Explanation of Signs

[0080] 1 Sheet post-processing apparatus 1E Expansion unit 1M Post-processing main body 13 Conveyance switching unit 13a Switching guide 14 Sheet conveyance path 16 Sheet discharge unit 16a Sheet discharge tray 17f Guide contact member 18 Cover member 18a Guide restricting unit 19 Conveyance guide 19a Fixed guide unit 19b Movable guide unit 53 Second discharge tray (main body discharge tray) 201 Image forming apparatus 301 Image forming system f1 First direction f2 Second direction

Claims

1. A post - processing main body unit that performs a predetermined post - processing on a sheet and discharges the sheet to a main body discharge tray; An additional unit that the sheet passing through the post - processing main body unit enters and is detachable from the post - processing main body unit; comprising: The post - processing main body unit includes a switching guide that switches the conveyance direction of the sheet between a first direction that guides the sheet passing through the post - processing main body unit to the main body discharge tray and a second direction that guides the sheet to the additional unit. The additional unit includes a guide contact member that contacts the switching guide when attached to the post - processing main body unit and changes the posture of the switching guide in the second direction. A sheet post - processing apparatus characterized by this.

2. The post - processing main body unit includes a cover member that is detachable from the attachment location of the additional unit when the additional unit is not attached. The cover member has a guide restricting portion that contacts the switching guide when attached to the post - processing main body unit and changes the posture of the switching guide in the first direction. The sheet post - processing apparatus according to claim 1, characterized by this.

3. The additional unit includes a conveyance guide that faces the switching guide across the conveyance path of the sheet conveyed in the second direction when attached to the post - processing main body unit. The sheet post - processing apparatus according to claim 1, characterized by this.

4. The conveyance guide: A fixed guide portion that is inserted into the post - processing main body unit when the additional unit is attached to the post - processing main body unit; A movable guide portion that is openable and closable and can expose the sheet conveyance path in the additional unit; having this. The sheet post - processing apparatus according to claim 3, characterized by this.

5. The fixed guide portion extends across from inside the post - processing main body unit to inside the additional unit. The sheet post - processing apparatus according to claim 4, characterized by this.

6. The sheet post-processing apparatus according to claim 1, wherein the additional unit has a plurality of stages of sheet discharge trays for sorting and discharging the sheet that has entered from the post-processing main body portion.

7. An image forming apparatus that forms an image on a sheet, The sheet post-processing apparatus according to any one of claims 1 to 6, which performs predetermined post-processing on the sheet on which an image has been formed in the image forming apparatus, An image forming system comprising:

Images