Sheet ejection device and sheet post-processing equipment with the same

Abstract

To provide a sheet ejection device capable of improving the loadability of folded and processed sheets with a simple configuration, and a sheet post-processing device equipped with the sheet ejection device.SOLUTION: A sheet post-processing device includes: a sheet ejection section; a liftable sheet ejection tray on which sheets ejected from the sheet ejection section are stacked; a sheet detection sensor that detects a stacking surface of sheets stacked on the sheet ejection tray on an upstream side in an ejection direction; a tray lifting motor that lifts and lowers the sheet ejection tray; and a control unit that controls the tray lifting motor. When the sheet detection sensor detects the stacking surface of the sheets, the control unit executes a tray lowering operation to lower the sheet ejection tray by a predetermined amount. When sheets stacked on the sheet ejection tray have been subjected to folding processing, the control unit increases the amount of lowering of the sheet ejection tray compared to when the sheets have not been subjected to folding processing.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a sheet discharging device that discharges a sheet subjected to a folding process for forming a fold on the sheet, and a sheet post-processing device including the sheet discharging device.

Background Art

[0002] A sheet post-processing device including a sheet folding device that performs a folding process for forming a fold on a sheet after image formation by an image forming device such as a copying machine or a printer is known.

[0003] When the folded sheet is discharged and stacked on a sheet stacking tray, the thickness of the folded portion of the sheet increases. For example, when discharging a Z-folded sheet onto a vertically movable sheet stacking tray, the folded portion is discharged so as to be on the back side with respect to the conveyance direction. Therefore, as the number of discharged sheets increases, the stacking height on the downstream side (back side) with respect to the upstream side (front side) of the sheet stacking tray in the discharge direction becomes larger.

[0004] On the other hand, in the sheet post-processing device, a sheet detection sensor is arranged on the upstream side of the sheet stacking tray with respect to the discharge direction to monitor the stacking height of the sheets. Therefore, a gap occurs between the stacking height of the sheets on the sheet stacking tray recognized by the control unit of the sheet post-processing device and the actual stacking height. As a result, when a newly Z-folded sheet is discharged while Z-folded sheets are stacked on the tray, they collide with each other, leading to the slipping of the sheets. Also, although Z-folded sheets are exemplified here, the same problems exist for sheets folded into inner three folds or outer three folds.

[0005] Patent Document 1 discloses a sheet processing apparatus that measures and calculates the distance from the home position of the paper discharge tray to the current position of the paper discharge tray and the distance to the folded portion of the stacked paper using a distance sensor, and moves the paper discharge tray up and down by a certain distance if the calculated distance does not match the distance to the upper limit position of paper stacking. The sheet processing apparatus performs the above processing until the calculated distance matches the distance to the upper limit position of paper stacking. Then, using paper thickness information, paper folding mode information, etc., the remaining number of sheets that can be stacked on the paper discharge tray is converted and calculated.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the configuration of Patent Document 1, it is necessary to separately provide a distance sensor for measuring the distance to the folded portion of the stacked paper, which is different from a paper surface sensor for detecting the upper surface of the unfolded paper, and there is a problem that the number of parts and costs increase.

[0008] In view of the above problems, an object of the present invention is to provide a sheet discharging device capable of improving the stackability of folded sheets with a simple configuration, and a sheet post-processing device equipped with the same.

Means for Solving the Problems

[0009] To achieve the above object, a first configuration of the present invention includes a sheet discharge unit, a sheet discharge tray, a sheet detection sensor, a tray lifting motor, and a control unit. The sheet discharge unit discharges a sheet. The sheet discharge tray is capable of moving up and down and is loaded with the sheet discharged from the sheet discharge unit. The sheet detection sensor detects the loading surface on the upstream side in the discharge direction of the sheet loaded on the sheet discharge tray. The tray lifting motor moves the sheet discharge tray up and down. The control unit controls the tray lifting motor. When the loading surface of the sheet is detected by the sheet detection sensor, the control unit executes a tray lowering operation of lowering the sheet discharge tray by a predetermined amount. When the sheet loaded on the sheet discharge tray is folded, the control unit increases the amount of descent of the sheet discharge tray compared to the case where the sheet is not folded.

Advantages of the Invention

[0010] According to the first configuration of the present invention, when the loading surface of the sheet loaded on the sheet discharge tray is detected by the sheet detection sensor and the sheet discharge tray is lowered, it is adjusted to an optimal amount of descent according to whether the sheet is folded or not. Thereby, it is possible to suppress the problem that the newly discharged sheet collides with the already loaded sheet and slides off the sheet discharge tray. In addition, since it is possible to control the raising and lowering of the sheet discharge tray only with the sheet detection sensor that detects the loading surface on the upstream side in the discharge direction, a sensor for detecting the loading surface on the downstream side in the discharge direction is not required, and the number of parts and costs can also be reduced.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of an image forming system including a sheet post-processing apparatus 1 having a second sheet discharge unit 6 which is an example of the sheet discharge apparatus of the present invention, and an image forming apparatus 200 to which the sheet post-processing apparatus 1 is connected.

[0013] As shown in Fig. 1, the image forming apparatus 200 prints an image on a sheet (paper) based on image data input from the outside via a network communication unit (not shown) or image data read by an image reading unit 201 disposed above the image forming apparatus 200.

[0014] The sheet post-processing device 1 is detachably connected to the side surface of the image forming apparatus 200. The sheet post-processing device 1 performs post-processing such as punch hole forming, binding, and folding on the sheet after image formation (printing) by the image forming apparatus 200. Note that the sheet post-processing device 1 is not limited to performing post-processing on the sheet automatically conveyed from the image forming apparatus 200, and it may convey the sheet set in a tray (not shown) by the user to a position where post-processing can be performed by itself and perform post-processing on the sheet.

[0015] FIG. 2 is a side cross-sectional view schematically showing the configuration of the sheet post-processing device 1 including the second sheet discharge unit 6. As shown in FIG. 2, the sheet post-processing device 1 includes a sheet inlet 2, a first sheet conveyance path 3, a first sheet discharge unit 4, a second sheet conveyance path 5, a second sheet discharge unit 6, a third sheet conveyance path 7, a third sheet discharge unit 8, a post-processing unit 9, and a post-processing control unit (control unit) 10.

[0016] The sheet inlet 2 is an opening provided on the side surface of the sheet post-processing device 1 facing the image forming apparatus 200. The sheet conveyed from the image forming apparatus 200 toward the sheet post-processing device 1 passes through the sheet inlet 2 and is carried into the interior of the sheet post-processing device 1.

[0017] The first sheet conveyance path 3 extends substantially horizontally in a direction away from the image forming apparatus 200 (left direction in FIG. 2) from the sheet inlet 2 to the first sheet discharge unit 4. The direction from the sheet inlet 2 toward the first sheet discharge unit 4 is referred to as the sheet conveyance direction in the first sheet conveyance path 3. The sheet inlet 2 is located at the upstream end of the first sheet conveyance path 3 in the sheet conveyance direction. The first sheet conveyance path 3 has a plurality of conveyance roller pairs 3r and conveys the sheet carried into the sheet post-processing device 1 from the sheet inlet 2 toward the downstream side in the sheet conveyance direction.

[0018] The first sheet discharge unit 4 is provided on the side surface of the sheet post-processing apparatus 1 opposite to the side surface facing the image forming apparatus 200. The first sheet discharge unit 4 is disposed at the downstream end of the first sheet conveyance path 3 in the sheet conveyance direction. The first sheet discharge unit 4 includes a first discharge port 41, a first discharge roller pair 42, and a first discharge tray 43.

[0019] The first discharge port 41 is located at the downstream end of the first sheet conveyance path 3 in the sheet conveyance direction. The first discharge roller pair 42 is disposed at the first discharge port 41. The first discharge tray 43 is located on the downstream side of the first discharge port 41 in the sheet conveyance direction. The sheet conveyed through the first sheet conveyance path 3 and reaching the first discharge port 41 is discharged onto the first discharge tray 43 through the first discharge port 41 by the first discharge roller pair 42. The first discharge tray 43 is one of the final discharge locations for the sheets post-processed by the sheet post-processing apparatus 1. Also, sheets that are not post-processed, small-sized sheets, etc. are also discharged onto the first discharge tray 43.

[0020] The second sheet conveyance path 5 branches from the first branch portion (branch portion) 31 on the first sheet conveyance path 3 and extends horizontally and upward in a direction away from the image forming apparatus 200 (left direction in FIG. 2) to the second sheet discharge unit 6. The first branch portion 31 is disposed on the downstream side of the punching portion 91 with respect to the sheet conveyance direction in the first sheet conveyance path 3. Note that the direction from the first branch portion 31 toward the second sheet discharge unit 6 is referred to as the sheet conveyance direction in the second sheet conveyance path 5. The first branch portion 31 is located at the upstream end of the second sheet conveyance path 5 in the sheet conveyance direction. The second sheet conveyance path 5 has a plurality of conveyance roller pairs 5r and conveys the sheet conveyed through the first sheet conveyance path 3 by branching it at the first branch portion 31 toward the second sheet discharge unit 6.

[0021] The first branch portion 31 has a first switching guide 311. The first switching guide 311 rotates between a first position (broken line P1 in FIG. 5) that guides the sheet conveyed on the first sheet conveyance path 3 from the sheet inlet 2 side to the first discharge port 41 along the first sheet conveyance path 3, and a second position (solid line P2 in FIG. 5) that branches off from the first sheet conveyance path 3 and guides it to the second sheet conveyance path 5. Further, the first switching guide 311 rotates to a third position (broken line P3 in FIG. 5) that guides the sheet that has undergone folding processing and passed through the second folding conveyance path 106 described later to the second sheet conveyance path 5. The first switching guide 311 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control unit 10.

[0022] The second sheet discharge portion 6 is provided above the first sheet discharge portion 4 on the side surface of the sheet post-processing apparatus 1 opposite to the side surface facing the image forming apparatus 200. The second sheet discharge portion 6 is disposed at the downstream end in the sheet conveyance direction of the second sheet conveyance path 5. The second sheet discharge portion 6 has a second discharge port 61, a second discharge roller pair 62, and a second discharge tray 63.

[0023] The second discharge port 61 is located at the downstream end in the sheet conveyance direction of the second sheet conveyance path 5. The second discharge roller pair 62 is disposed at the second discharge port 61. The second discharge tray 63 is located on the downstream side in the sheet conveyance direction of the second discharge port 61. The sheet conveyed through the second sheet conveyance path 5 and reaching the second discharge port 61 is discharged onto the second discharge tray 63 through the second discharge port 61 by the second discharge roller pair 62. The second discharge tray 63 is one of the final discharge locations for the sheets that have undergone post-processing by the sheet post-processing apparatus 1. Sheets that have not undergone post-processing, small-sized sheets, etc. are also discharged onto the second discharge tray 63.

[0024] The third sheet conveyance path 7 extends downward from a second branch portion 32 on the first sheet conveyance path 3 to a third sheet discharge portion 8. The direction from the second branch portion 32 toward the third sheet discharge portion 8 is referred to as the sheet conveyance direction in the third sheet conveyance path 7. The second branch portion 32 is located on the downstream side of the first branch portion 31 with respect to the sheet conveyance direction of the first sheet conveyance path 3 and at the upstream end of the third sheet conveyance path 7 in the sheet conveyance direction. The third sheet conveyance path 7 has a plurality of conveyance roller pairs 7r and branches the sheet conveyed on the first sheet conveyance path 3 at the second branch portion 32 and conveys it toward the third sheet discharge portion 8.

[0025] The second branch portion 32 has a second switching guide 321. The second switching guide 321 rotates between a first position (see FIG. 5) that guides the sheet conveyed on the first sheet conveyance path 3 from the sheet inlet 2 side along the first sheet conveyance path 3 to the first discharge port 41 and a second position (not shown) that guides the sheet that has been conveyed on the first sheet conveyance path 3 from the sheet inlet 2 side, passed through the second branch portion 32, and then switched back to the third sheet conveyance path 7. The second switching guide 321 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control unit 10.

[0026] The third sheet discharge portion 8 is provided on the side surface of the sheet post-processing device 1 opposite to the side surface facing the image forming apparatus 200 and below the first sheet discharge portion 4 (near the lower end portion of the sheet post-processing device 1). The third sheet discharge portion 8 has a third discharge port 81, a third discharge roller pair 82, and a third discharge tray 83.

[0027] The third discharge port 81 is located at the downstream end of the third sheet conveyance path 7 in the sheet conveyance direction. The third discharge roller pair 82 is disposed at the third discharge port 81. The third discharge tray 83 is located on the downstream side of the third discharge port 81 in the sheet conveyance direction. The sheet conveyed on the third sheet conveyance path 7 and reaching the third discharge port 81 is discharged onto the third discharge tray 83 through the third discharge port 81 by the third discharge roller pair 82. The third discharge tray 83 is one of the final discharge locations for the sheets that have been post-processed by the sheet post-processing device 1.

[0028] The post-processing unit 9 performs predetermined post-processing on the sheets that are image-formed by the image forming apparatus 200 and carried into the sheet post-processing apparatus 1. The post-processing unit 9 includes a punching unit 91, a stapling unit 92, a sheet folding unit 100, and a binding unit 94.

[0029] The punching unit 91 is disposed immediately downstream of the sheet inlet 2 in the first sheet conveyance path 3. The punching unit 91 performs a punching process on the sheet conveyed on the first sheet conveyance path 3 to form punch holes.

[0030] The stapling unit 92 is disposed immediately upstream of the first sheet discharge unit 4 with respect to the sheet conveyance direction of the first sheet conveyance path 3. The stapling unit 92 performs a stapling process (binding process) on the stack of sheets formed by stacking a plurality of sheets to bind the stack of sheets.

[0031] The sheet folding unit 100 is disposed downstream of the punching unit 91 and upstream of the stapling unit 92 with respect to the sheet conveyance direction of the first sheet conveyance path 3. In other words, the sheet folding unit 100 is located upstream of the first branch portion 31 with respect to the sheet conveyance direction of the first sheet conveyance path 3. The sheet folding unit 100 performs a folding process on a single sheet to form a fold line.

[0032] The sheet folding unit 100 can perform folding processes such as double folding, Z-folding, outside triple folding, and inside triple folding on a single sheet. The detailed configuration of the sheet folding unit 100 will be described later.

[0033] FIGS. 3(a) to 3(c) are side views of the sheet S that has been Z-folded, outside triple-folded, and inside triple-folded, respectively.

[0034] The Z-fold is a folding method in which, as shown in FIG. 3(a) for example, the downstream side of the sheet S in the sheet conveyance direction of the first sheet conveyance path 3 is formed in a Z shape when viewed from the sheet width direction orthogonal to the sheet conveyance direction. In the Z-fold, the downstream portion Sd of the sheet S on the downstream side of the first folding line F1 in the first sheet conveyance path 3 and the upstream portion Su on the upstream side of the second folding line F2 face each other in the vertical direction with the intermediate portion Sc between the two folding lines therebetween. In the sheet conveyance direction, the lengths of the downstream portion Sd and the intermediate portion Sc of the sheet S are substantially the same and shorter than the length of the upstream portion Su.

[0035] The outside triple-fold is a folding method in which, as shown in FIG. 3(b) for example, the entire sheet S is formed in a Z shape when viewed from the sheet width direction. In the outside triple-fold, the downstream portion Sd of the sheet S on the downstream side of the first folding line F1 in the first sheet conveyance path 3 and the upstream portion Su on the upstream side of the second folding line F2 face each other in the vertical direction with the intermediate portion Sc between the two folding lines therebetween. In the sheet conveyance direction, the lengths of the downstream portion Sd, the intermediate portion Sc, and the upstream portion Su of the sheet S are substantially the same.

[0036] The inside triple-fold is a folding method in which, as shown in FIG. 3(c) for example, the upstream portion Su of the sheet S on the upstream side of the first folding line F1 and the downstream portion Sd on the downstream side of the second folding line F2 in the sheet conveyance direction of the first sheet conveyance path 3 are in surface contact with each other facing in the vertical direction on one side (the upper side in FIG. 3(c)) of the plane of the intermediate portion Sc between the two folding lines.

[0037] The manufacturing department 94 is arranged closest to the upstream side of the third sheet discharge portion 8 with respect to the sheet conveyance direction of the third sheet conveyance path 7. The manufacturing department 94 has a middle folding portion 941 and a middle binding portion 942. The manufacturing department 94 performs a middle folding process and a middle binding process of folding and binding the substantially central portion in the sheet conveyance direction on a sheet bundle formed by stacking a plurality of sheets to form a booklet.

[0038] The post - processing control unit 10 includes a CPU, a storage unit, and other electronic circuits and components (all not shown). The post - processing control unit 10 receives input instructions from the main control unit 203 of the image forming apparatus 200 or the operation panel 11 of the sheet post - processing apparatus 1 (both shown in FIG. 1), and based on the control programs and data 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 processes related to the functions of the sheet post - processing apparatus 1. Each of the first sheet conveyance path 3, the first sheet discharge unit 4, the second sheet conveyance path 5, the second sheet discharge unit 6, the third sheet conveyance path 7, the third sheet discharge unit 8, and the post - processing unit 9 receives individual commands from the post - processing control unit 10 and performs post - processing on the sheet in conjunction. Note that the function of the post - processing control unit (control unit) 10 may be shared by the main control unit 203 of the image forming apparatus 200.

[0039] Subsequently, the configuration of the sheet folding unit 100 will be described with reference to FIGS. 4 and 5. FIG. 4 is a partial cross - sectional view showing the periphery of the sheet folding unit 100 in the sheet post - processing apparatus 1 of FIG. 2. FIG. 5 is a cross - sectional view showing the periphery of the sheet folding unit 100 of FIG. 4. The sheet folding unit 100 includes a first folding portion 101, a first folding conveyance path 102, a first folding roller pair 103, a first folding guide 104, a second folding portion 105, a second folding conveyance path 106, a second folding roller pair 107, and a second folding guide 108.

[0040] Also, conveyance roller pairs 3r are arranged at two locations of the sheet folding unit 100 along the first sheet conveyance path 3. Hereinafter, among the conveyance roller pairs 3r arranged at the two locations of the sheet folding unit 100, the upstream conveyance roller pair 3r composed of the second roller 112 and the conveyance roller 114 is referred to as the first assist roller pair 3r1, and the downstream conveyance roller pair 3r is referred to as the second assist roller pair 3r2.

[0041] The first folding portion 101 is disposed on the first sheet conveyance path 3. Specifically, the first folding portion 101 is located downstream of the perforation portion 91 (see FIG. 2) with respect to the sheet conveyance direction on the first sheet conveyance path 3 and upstream of the first branch portion 31.

[0042] The first folding conveyance path 102 branches from the first folding portion 101 on the first sheet conveyance path 3 and extends downward. In the present embodiment, the first folding conveyance path 102 extends substantially vertically downward from the first folding portion 101. The lower end portion of the first folding conveyance path 102 is connected to the third sheet conveyance path 7.

[0043] The first folding roller pair 103 is disposed on the first folding conveyance path 102 at the first folding portion 101. The first folding roller pair 103 is composed of a first roller 111 disposed on one side sandwiching the first folding conveyance path 102 and a second roller 112 disposed on the other side. The first folding roller pair 103 forms a first folding nip portion N1 when one of the first roller 111 and the second roller 112 is urged toward the other and comes into contact. The sheet that has entered the first folding conveyance path 102 passes through the first folding nip portion N1 and is conveyed downward under the first folding roller pair 103.

[0044] Note that the second roller 112 and the conveyance roller 114 together constitute a first assist roller pair 3r1.

[0045] The first folding guide 104 is disposed opposite to the first folding nip portion N1 at the first folding portion 101. Specifically, the first folding guide 104 is disposed upstream of the first folding nip portion N1 (the upper side in FIG. 4) with respect to the sheet conveyance direction of the first folding conveyance path 102. When the sheet is not subjected to a folding process, the first folding guide 104 retreats in a direction away from the first folding nip portion N1 from the first sheet conveyance path 3, that is, retreats upward from the first sheet conveyance path 3 in FIG. 4. Thereby, the sheet passing through the first sheet conveyance path 3 does not contact the first folding guide 104.

[0046] The first folding guide 104 is connected to a guide drive mechanism (not shown) and is capable of reciprocating in a direction approaching and separating from the first folding nip portion N1. The first folding guide 104 guides the sheet conveyed on the first sheet conveyance path 3 to the first folding nip portion N1.

[0047] The second folding portion 105 is disposed on the first folding conveyance path 102. Specifically, the second folding portion 105 is located downstream of the first folding roller pair 103 with respect to the sheet conveyance direction of the first folding conveyance path 102 and below the first folding nip portion N1.

[0048] The second folding conveyance path 106 branches off from the second folding portion 105 on the first folding conveyance path 102 and extends. The second folding conveyance path 106 extends toward the side surface side (the left side in FIG. 4) of the sheet post-processing apparatus 1 provided with the first sheet discharge portion 4 from the second folding portion 105. In other words, the second folding conveyance path 106 extends in substantially the same direction as the extending direction of the first sheet conveyance path 3.

[0049] The first sheet conveyance path 3 includes a confluence portion 33 located downstream of the first branch portion 31 in the sheet conveyance direction. The second folding conveyance path 106 merges into the first sheet conveyance path 3 at the confluence portion 33. In other words, the confluence portion 33 is located downstream of the first branch portion 31 with respect to the sheet conveyance direction of the first sheet conveyance path 3, and the sheets subjected to the folding process by the sheet folding unit 100 merge.

[0050] In the present embodiment, the confluence portion 33 is located in the vicinity of the first switching guide 311. The first switching guide 311 is switchable to a first position P1, a second position P2, and a third position P3 (all shown in FIG. 5). The first switching guide 311 disposed at the first position P1 guides the sheet conveyed on the first sheet conveyance path 3 from the sheet inlet 2 side to the first discharge port 41. The first switching guide 311 disposed at the second position P2 guides the sheet conveyed on the first sheet conveyance path 3 to the second sheet conveyance path 5. The first switching guide 311 disposed at the third position P3 guides the folded sheet conveyed on the second folding conveyance path 106 to the second discharge port 61 via the second sheet conveyance path 5.

[0051] The second folding roller pair 107 is disposed on the second folding conveyance path 106 in the second folding unit 105. The second folding roller pair 107 is composed of a first roller 111 disposed on one side with the second folding conveyance path 105 interposed therebetween and a third roller 113 disposed on the other side. The second folding roller pair 107 forms a second folding nip portion N2 when one of the first roller 111 and the third roller 113 is urged toward the other and comes into contact therewith. The sheet that has entered the second folding conveyance path 106 passes through the second folding nip portion N2 and is conveyed toward the merging portion 33 side (the left side of the second folding roller pair 107 in FIG. 4).

[0052] The second folding guide 108 is disposed to face the second folding nip portion N2 in the second folding unit 105. Specifically, the second folding guide 108 is disposed on the upstream side (the right side in FIG. 4) of the second folding nip portion N2 with respect to the sheet conveyance direction of the second folding conveyance path 106. When no folding process is performed on the sheet, the second folding guide 108 retracts in a direction away from the second folding nip portion N2 with respect to the first folding conveyance path 102, that is, to the right side of the first folding conveyance path 102 in FIG. 4. Thereby, the sheet passing through the first folding conveyance path 102 does not contact the second folding guide 108.

[0053] The second folding guide 108 is connected to a drive mechanism (not shown) and is capable of reciprocating in a direction approaching and separating from the second folding nip portion N2. The second folding guide 108 guides the sheet conveyed on the first folding conveyance path 102 to the second folding nip portion N2.

[0054] Subsequently, the operation of the sheet folding unit 100 will be described with reference to FIGS. 5 and 6. Regarding the operation of the sheet folding unit 100, as an example, the operation of triple-folding the sheet into an inner triple-fold as shown in FIG. 3(c) will be described. FIGS. 5 and 6 are cross-sectional views showing the periphery of the sheet folding unit 100 in FIG. 4, and show the initial stage and the final stage of the transition of the inner triple-fold process of the sheet S.

[0055] As shown in FIG. 5, the sheet S carried into the first sheet conveyance path 3 from the sheet inlet 2 (see FIG. 2) has its downstream portion in the sheet conveyance direction guided from the first branch portion 31 to the second sheet conveyance path 5. The first switching guide 311 of the first branch portion 31 is located at the second position P2 that guides the sheet S conveyed on the first sheet conveyance path 3 from the sheet inlet 2 side to the second sheet conveyance path 5.

[0056] In addition, at the first folding portion 101, the first folding guide 104 is arranged in a direction away from the first folding nip portion N1 from the first sheet conveyance path 3, that is, at a position (retracted position) retracted upward from the first sheet conveyance path 3 in FIG. 5.

[0057] When the portion corresponding to the first fold line F1 of the sheet S (see FIG. 3(c)) reaches the first folding portion 101, the rotation of the second assist roller pair 3r2, the first assist roller pair 3r1, and each conveyance roller pair 5r of the second sheet conveyance path 5 is stopped, and the conveyance of the sheet S is stopped.

[0058] With the first assist roller pair 3r1 stopped, by reversely rotating the second assist roller pair 3r2 and each conveyance roller pair 5r of the second sheet conveyance path 5, the portion of the sheet S downstream of the first assist roller pair 3r1 moves upstream (the right side in FIG. 5), and the sheet S bends at the first folding portion 101. Then, the first folding guide 104 starts to move from the retracted position toward the first folding nip portion N1.

[0059] While further reversely rotating the second assist roller pair 3r2, the first folding guide 104 is moved to a position (folding position) where it contacts the first folding nip portion N1 through the sheet S. When the first folding guide 104 moves from the retracted position to the folding position, the bent portion of the sheet S is guided to the first folding nip portion N1. In this way, by moving the first folding guide 104 to the folding position after forming a bend in the sheet S, an excessive load on the sheet S by the first folding guide 104 does not act, and the occurrence of wrinkles and breakage of the sheet S can be suppressed. The first fold line F1 is formed on the sheet S that has passed through the first folding nip portion N1.

[0060] Note that the timing for forming the first fold line F1 on the sheet S is determined based on the detection timing of the downstream end in the sheet conveyance direction in the first sheet conveyance path 3 of the sheet S by a sheet detection sensor (not shown), the total length of the sheet S in the sheet conveyance direction, and the conveyance speed of the sheet S. The same applies to the timing for forming the second fold line F2 described later.

[0061] Also, in the second folding portion 105, the second folding guide 108 is retracted in a direction away from the second folding nip portion N2 from the first folding conveyance path 102 (to the right of the first folding conveyance path 102 in FIG. 5).

[0062] The sheet S that has passed through the first folding nip portion N1 is conveyed in a direction away from the first folding roller pair 103 (downward) along the first folding conveyance path 102 with two regions extending along the sheet conveyance direction overlapping with the portion of the first fold line F1 at the head. The upstream portion in the conveyance direction of the sheet S that has passed through the first folding conveyance path 102 temporarily enters the third sheet conveyance path 7.

[0063] When the portion corresponding to the second fold line F2 of the sheet S (see FIG. 3(c)) reaches the second folding portion 105, the rotation of the second assist roller pair 3r2, the first assist roller pair 3r1, each conveyance roller pair 5r of the second sheet conveyance path 5, the first folding roller pair 103, and each conveyance roller pair 7r of the third sheet conveyance path 7 is stopped, and the conveyance of the sheet S is stopped.

[0064] After stopping the conveyance of the sheet S, by rotating each conveyance roller pair 7r of the third sheet conveyance path 7 in the reverse direction, the portion of the sheet S on the downstream side in the sheet conveyance direction from the second folding portion 105 (below the second folding portion 105 in FIG. 5) moves to the upstream side (above in FIG. 5), and the sheet S is bent at the location of the second folding portion 105.

[0065] Subsequently, the second folding guide 108 moves in a direction approaching the second folding nip portion N2 and contacts the sheet S. When the second folding guide 108 contacts the sheet S, the bent portion of the sheet S is guided to the second folding nip portion N2 of the second folding roller pair 107. Then, a second fold line F2 is formed on the sheet S that has passed through the second folding nip portion N2 (see FIG. 6).

[0066] As shown in FIG. 6, the sheet S that has passed through the second folding nip portion N2 is conveyed in a direction away from the second folding roller pair 107 along the second folding conveyance path 106 with three regions extending along the sheet conveyance direction overlapping with the portion of the second fold line F2 at the head. The upstream portion in the conveyance direction of the sheet S that has passed through the second folding conveyance path 106 enters the confluence portion 33. At this time, in the confluence portion 33, the sheet S is guided to the second sheet conveyance path 5 by the first switching guide 311 disposed at the third position P3, passes through the second discharge port 61, and is discharged to the second sheet discharge portion 6 (see FIG. 2).

[0067] When the post-processing control unit 10 performs a folding process on the sheet S in the sheet folding unit 100, after guiding the downstream portion in the sheet conveyance direction of the sheet S carried into the first sheet conveyance path 3 from the sheet conveyance inlet 2 to the second sheet conveyance path 5 from the first branch portion 31, the post-processing control unit 10 reverses the conveyance direction of the sheet S to guide the sheet S to the sheet folding unit 100 and performs a folding process on the sheet S. Further, the post-processing control unit 10 merges the folded sheet S into the second sheet conveyance path 5 at the confluence portion 33.

[0068] As described above, the inner triple-fold process of the sheet S has been explained. However, for the Z-fold process in which the sheet S is Z-folded as shown in FIG. 3(a) and the outer triple-fold process in which the sheet S is outer triple-folded as shown in FIG. 3(b), by changing the timing of forming the first fold line F1 and the second fold line F2 on the sheet S, it can be performed in exactly the same manner as the procedure shown in FIGS. 5 and 6.

[0069] FIG. 7 is a cross-sectional view showing the periphery of the sheet folding unit 100 and shows an initial stage of the double-folding process of the sheet S. When double-folding the sheet S, the sheet S is carried into the sheet folding unit 100 with the first folding guide 104 disposed at the folding position. Thereby, the leading end of the sheet S is guided to the first folding nip portion N1 along the first folding guide 104 and the second roller 112.

[0070] Next, the center of the sheet S is stopped at a position facing the second folding nip portion N2 of the second folding roller pair 107. In this state, by moving the second folding guide 108 in a direction approaching the second folding nip portion N2 and bringing it into contact with the sheet S, the center of the sheet S is guided to the second folding nip portion N2 of the second folding roller pair 107. Thereby, a crease is formed in the sheet S that has passed through the second folding nip portion N2, and the double-folding process is performed. The double-folded sheet S is guided to the second sheet conveyance path 5 by the first switching guide 311 disposed at the third position P3, and is discharged through the second discharge port 61 to the second sheet discharge portion 6 (see FIG. 2).

[0071] FIG. 8 is a side cross-sectional view of the periphery of the second sheet discharge portion 6 of the sheet post-processing apparatus 1. FIG. 9 is a perspective view of the periphery of the second sheet discharge portion 6 as viewed from above. Both the sheet S that has been folded by the sheet folding unit 100 and the sheet S that has not been folded are discharged to the second sheet discharge portion 6. The second sheet discharge portion 6 includes a second discharge roller pair 62, a second discharge tray 63, a tray lifting motor 65, and a sheet detection sensor 67.

[0072] The second discharge tray 63 has a tray upper surface 63a and a rear wall portion 63b. The tray upper surface 63a is loaded with the sheet S that has been folded by the sheet folding unit 100 and discharged from the second discharge port 61 by the second discharge roller pair 62. The rear wall portion 63b rises from an end portion on the upstream side in the discharge direction of the tray upper surface 63a. The second discharge tray 63 is lifted and lowered by the tray lifting motor 65.

[0073] The sheet detection sensor 67 is disposed inside (on the upstream side in the discharge direction) the rear wall surface 63a of the second discharge tray 63, near directly below the second discharge roller pair 62, and detects the loading surface of the sheet S loaded on the tray upper surface 63a.

[0074] The sheet detection sensor 67 is a reflective PI (photo interrupter) sensor provided with a detection unit having a light emitting unit and a light receiving unit. When the number of sheets of the folded sheet S loaded on the tray upper surface 63a reaches a certain number or more, the loading surface (upper surface) of the sheet S comes within the detection area of the sheet detection sensor 67. In this state, the detection unit of the sheet detection sensor 67 can detect the reflected light from the sheet S (in the on state), and detects the loading surface of the sheet S loaded on the tray upper surface 63a.

[0075] FIG. 9 is a side cross-sectional view showing a state in which a Z-folded sheet S (hereinafter referred to as a folded sheet Sf) is loaded on the second discharge tray 63. As shown in FIG. 9, when the folded sheet Sf is loaded on the tray upper surface 63a of the second discharge tray 63, as the number of loaded folded sheets Sf increases, the loading height on the downstream side (left side in FIG. 9) with respect to the upstream side (right side in FIG. 9) of the sheet loading tray in the discharge direction becomes larger.

[0076] Here, since the sheet detection sensor 67 detects the loading surface on the upstream side in the discharge direction (right side in FIG. 9) of the folded sheet Sf, a gap is generated between the loading surface (loading height) on the upstream side in the discharge direction detected by the sheet detection sensor 67 and the loading surface (loading height) on the downstream side in the discharge direction. As a result, even if the loading surface on the upstream side in the discharge direction detected by the sheet detection sensor 67 is below the second discharge port 61, the loading surface on the downstream side in the discharge direction may reach above the second discharge port 61, and the newly discharged folded sheet Sf may collide with the already loaded folded sheet Sf and may slip off the second discharge tray 63.

[0077] Therefore, in this embodiment, after the loading surface of the sheet S is detected by the sheet detection sensor 67, control is performed to lower the second discharge tray 63 by a certain distance. Then, based on whether the sheet S loaded on the second discharge tray 63 has been subjected to a folding process and the type of folding process, the amount of descent of the second discharge tray 63 is changed.

[0078] Specifically, the amount of descent when the sheet S is not subjected to a folding process is stored as a reference amount of descent. When the sheet S is subjected to a folding process, the post-processing control unit 10 refers to the stored reference amount of descent and determines the amount of descent of the second discharge tray 63 according to the type of folding process. For example, in the case of a sheet S subjected to a Z-fold process, since the thickness of the sheet S on the downstream side in the discharge direction is about three times that on the upstream side in the discharge direction, the amount of descent of the second discharge tray 63 is set to three times the reference amount of descent.

[0079] In the case of an inner three-fold process or an outer three-fold process, the amount of descent of the second discharge tray 63 is set to three times the reference amount of descent in consideration of the swelling of the sheet S after discharge, similar to the Z-fold process. In the case of a two-fold process, the amount of descent of the second discharge tray 63 is set to twice the reference amount of descent.

[0080] FIG. 10 is a flowchart showing an example of the lifting control of the second discharge tray 63 in the sheet post-processing apparatus 1. The lifting operation of the second discharge tray 63 will be described along the steps of FIG. 10 while referring to FIGS. 1 to 9 as necessary. In the initial state, it is assumed that the second discharge tray 63 is disposed at a reference position that has descended by a certain distance from the second discharge port 61.

[0081] When a post-processing command for the sheet S is input from the main body control unit 203 (see FIG. 1) of the image forming apparatus 200, the loading of the sheet S into the sheet post-processing apparatus 1 is started (step S1). Then, a predetermined post-processing (punching process, binding process, folding process) is performed on the sheet S in the sheet post-processing apparatus 1. The sheet S subjected to the post-processing is discharged to the second discharge tray 63 (step S2).

[0082] Next, the post-processing control unit 101 determines whether the sheet detection sensor 67 is in the on state (step S3). If the sheet detection sensor 67 is in the off state (No in step S3), the discharge of the sheet S to the second discharge tray 63 continues. If the sheet detection sensor 67 is in the on state (Yes in step S3), since the stacking surface of the sheet S stacked on the second discharge tray 63 has risen to a predetermined height, the post-processing control unit 10 transmits a control signal to the tray lifting motor 65 to lower the second discharge tray 63 (step S4).

[0083] Next, the post-processing control unit 101 determines whether the Z-fold process has been performed on the sheet S (step S5). If the Z-fold process is present (Yes in step S5), the second discharge tray 63 is stopped at a position where it is lowered by three times the reference lowering amount (step S6). On the other hand, if there is no Z-fold process (No in step S5), after the second discharge tray 63 has been lowered and the sheet detection sensor 67 has become off, the lowering of the second discharge tray 63 is immediately stopped (step S7).

[0084] Thereafter, the post-processing control unit 101 determines whether the discharge of the sheet S has ended (step S8). If the discharge of the sheet S continues (No in step S8), the process returns to step S3, and the discharge of the sheet S to the second discharge tray 63 and the lowering operation of the second discharge tray 63 based on the detection result of the sheet detection sensor 67 continue (steps S3 to S8). If the discharge of the sheet S has ended (Yes in step S8), the process ends.

[0085] According to the control example shown in FIG. 10, the loading surface of the sheet S loaded on the second discharge tray 63 is detected by the sheet detection sensor 67. When the second discharge tray 63 is lowered, it is adjusted to an optimal lowering amount according to whether the sheet S has been Z-folded or not. Specifically, when the sheet S has been Z-folded and the loading surface (loading height) on the downstream side in the discharge direction is high, the second discharge tray 63 is lowered to a position three times the reference lowering amount. Thereby, it is possible to suppress the problem that the newly discharged sheet S collides with the already loaded sheet S and slides off the second discharge tray 63.

[0086] In addition, since the lifting and lowering of the second discharge tray 63 can be controlled only by the sheet detection sensor 67 that detects the loading surface (loading height) on the upstream side in the discharge direction, a sensor for detecting the loading surface (loading height) on the downstream side in the discharge direction is not required, and the number of components and costs can also be reduced.

[0087] In FIG. 10, the lifting and lowering control of the second discharge tray 63 at the time of discharging the sheet S subjected to the Z-fold process has been described. However, the same lifting and lowering control as in FIG. 10 can also be performed for the lifting and lowering control of the second discharge tray 63 at the time of discharging the sheet S subjected to the inner triple-fold process or the outer triple-fold process.

[0088] In addition, for the lifting and lowering control of the second discharge tray 63 at the time of discharging the sheet S subjected to the double-fold process, the same lifting and lowering control as in FIG. 10 can be performed except that the second discharge tray 63 is stopped at a position where it is lowered by twice the reference lowering amount in step S6.

[0089] As described above, the embodiments of the present invention have been described. However, the scope of the present invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, the post-processing control unit 10 automatically determines the lowering amount of the second discharge tray 63 based on the presence or absence of the folding process on the sheet S and the type of the folding process. However, the user may be able to input the lowering amount of the second discharge tray 63 from the operation panel 11 at an arbitrary timing.

[0090] Also, in the above embodiment, the sheet subjected to the folding process by the sheet folding unit 100 is discharged to the second sheet discharge unit 6, but it may be configured to discharge the sheet subjected to the folding process to the first sheet discharge unit 4. In that case, the above control may be applied to the raising and lowering of the first discharge tray 43 of the first sheet discharge unit 4.

[0091] Also, in the above embodiment, as the sheet discharge device of the present invention, the second sheet discharge unit 6 of the sheet post-processing device 1 provided with the sheet folding unit 100 that performs a folding process on the sheet is exemplified, but the present invention is not limited to this. For example, it is similarly applicable to the sheet discharge unit of the sheet post-processing device 1 in which the sheet post-processing device 1 does not include the sheet folding unit 100 and a folded sheet subjected to a folding process by a separate sheet folding device is carried in.

Industrial Applicability

[0092] The present invention can be used for a sheet discharge device that discharges a sheet subjected to a folding process for forming a fold line on the sheet, and a sheet post-processing device provided with the sheet discharge device.

Explanation of Signs

[0093] 1 Sheet post-processing device 2 Sheet inlet 3 First sheet conveyance path 3r Pair of conveyance rollers 3r1 First assist roller pair 3r2 Second assist roller pair 4 First sheet discharge unit 5 Second sheet conveyance path 6 Second sheet discharge unit (sheet discharge device) 10 Post-processing control unit (control unit) 11 Operation panel (input unit) 61 Second discharge port (sheet discharge unit) 62 Second discharge roller pair 63 Second discharge tray (sheet discharge tray) 63a Tray upper surface 63b Rear wall portion 65 Tray lifting motor 67 Sheet detection sensor 100 Sheet folding unit S Sheet Sf Folded sheet

Claims

1. A sheet discharge unit that discharges a sheet, A liftable sheet discharge tray on which the sheet discharged from the sheet discharge unit is loaded, A sheet detection sensor that detects the loading surface on the upstream side in the discharge direction of the sheet loaded on the sheet discharge tray, A tray lift motor that raises and lowers the sheet discharge tray, A control unit that controls the tray lift motor, Comprising: The control unit: When the loading surface of the sheet is detected by the sheet detection sensor, it executes a tray lowering operation to lower the sheet discharge tray by a predetermined amount, When the sheet loaded on the sheet discharge tray is subjected to a folding process, the amount of descent of the sheet discharge tray is increased compared to the case where the sheet is not subjected to a folding process. A sheet discharge device characterized by this.

2. When the amount of descent of the sheet discharge tray when the sheet is not subjected to a folding process is defined as the reference descent amount, The sheet discharge device according to claim 1, characterized in that when any one of a Z-fold process, an inner triple-fold process, and an outer triple-fold process is applied to the sheet loaded on the sheet discharge tray, the amount of descent of the sheet discharge tray is three times the reference descent amount.

3. When the amount of descent of the sheet discharge tray when the sheet is not subjected to a folding process is defined as the reference descent amount, The sheet discharge device according to claim 1, characterized in that when a double-fold process is applied to the sheet loaded on the sheet discharge tray, the amount of descent of the sheet discharge tray is twice the reference descent amount.

4. Comprising an input unit for inputting the amount of descent of the sheet discharge tray, When there is an input operation to the input unit, the control unit changes the amount of descent of the sheet discharge tray to the amount of descent input to the input unit. The sheet discharge device according to claim 1, characterized by this.

5. A folding unit that performs a predetermined folding process on the sheet, The sheet discharge device according to any one of claims 1 to 4 provided on the downstream side of the folding unit with respect to the conveyance direction of the sheet, A sheet post-processing device comprising.

Images