Sheet processing device

Abstract

To provide a sheet processing device capable of speeding up sheet alignment for post-processing and achieving efficiency of the alignment by dropping a sheet on a loading tray by any of a plurality of sheet dropping members correspondingly to the size of the sheet to be post-processed.SOLUTION: A sheet processing device comprises: a loading tray 37; and a sheet guide part 50 having a plurality of sheet dropping members 51 which drop sheets discharged for post-processing to the loading tray, and a pair of alignment plates 62 which bring the sheets loaded on the loading tray 37 into contact with the side edges in the width direction to align the sheets. The sheet dropping members 51 are disposed above the loading tray 37 in the width direction of the sheets, are disposed so that a moving range of the pair of alignment plates 62 and a part of the position where the sheet dropping member 51 comes into contact with the sheet overlap each other. Any of the sheet dropping members 51 is lowered correspondingly to the size in the width direction of the sheet discharged onto the loading tray 37 to drop the sheet on the loading tray 37.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus provided with alignment means when post-processing a sheet.

Background Art

[0002] Generally, a sheet processing apparatus is connected to a paper discharge port of an image forming apparatus, and temporarily holds the image-formed sheet in a conveyance path or on a processing tray, and post-processing such as punching or folding is performed.

[0003] This type of sheet processing apparatus includes a processing tray for stacking image-formed sheets and performing predetermined post-processing. After aligning a plurality of sheets on this processing tray, predetermined post-processing is executed. When aligning the sheets, it is necessary to stack the sheets discharged from the image forming apparatus in sequence so that they do not bend. For this reason, a sheet processing apparatus provided with a sheet dropping member for forcibly dropping and pressing the sheet discharged from the image forming apparatus onto the processing tray is known. The sheets stacked on the processing tray in this way are aligned in the width direction of the sheet, but it is necessary to prevent interference between the sheet dropping member and the member for alignment at that time. Patent Document 1 discloses a sheet processing apparatus provided with control means for preventing such interference.

[0004] The control means disclosed in Patent Document 1 is configured to perform alignment in the width direction of the sheet after executing sheet dropping when the size of the sheet in the width direction is less than a predetermined specified size, and to simultaneously execute sheet dropping and alignment in the width direction of the sheet when the size of the sheet in the width direction is greater than or equal to the specified size.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the control means disclosed in Patent Document 1, since the order of alignment with the sheet dropping must be switched according to the size of the sheet, the control becomes complicated. In addition, the amount of movement of the alignment member for performing alignment in the width direction of the sheet may increase according to the size of the sheet, which has contributed to a decrease in productivity.

[0007] Therefore, an object of the present invention is to provide a sheet processing apparatus that speeds up and improves the efficiency of sheet alignment for post-processing by dropping a sheet onto a stacking tray by any one of a plurality of sheet dropping members corresponding to the size of the sheet to be post-processed.

Means for Solving the Problems

[0008] In order to solve the above problems, a sheet processing apparatus of the present invention includes a pair of discharge rollers for discharging a sheet, a stacking tray on which the sheet discharged by the pair of discharge rollers is stacked, a sheet dropping member for dropping the sheet discharged by the pair of discharge rollers onto the stacking tray, and a sheet guide unit having a pair of alignment members that abut against and align the side edges in the width direction of the sheet stacked on the stacking tray. In the sheet processing apparatus, the sheet dropping members are provided in plurality along the width direction of the sheet above the stacking tray, and are arranged such that a part of the movement range of the pair of alignment members overlaps with the position where the sheet dropping member contacts the sheet, and any one of the plurality of sheet dropping members is lowered to drop the sheet onto the stacking tray according to the width size of the sheet discharged by the pair of discharge rollers.

Effects of the Invention

[0009] According to the sheet processing apparatus of the present invention, since any one of the plurality of sheet dropping members is lowered to drop the sheet onto the stacking tray corresponding to the sheet size, it is possible to efficiently correct the deflection of the sheet for a sheet of a predetermined size while having a configuration corresponding to various sheet sizes.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, with reference to FIG. 1, an overview of an image forming system A including a sheet processing apparatus C of the present invention will be described. The image forming system A is composed of an image forming apparatus B and a sheet processing apparatus C. The image forming apparatus B and the sheet processing apparatus C are connected via a discharge port 3 of the image forming apparatus B and an inlet 22 of the sheet processing apparatus C. The sheet on which an image is formed by the image forming apparatus B is discharged to either the first paper discharge tray 21a or the second paper discharge tray 21b via the sheet processing apparatus C. In the sheet processing apparatus C, various post-treatments such as sheet folding and stapling are performed according to specifications. In the following description, the leading edge of the sheet refers to the end in the sheet conveyance (paper discharge) direction, and the trailing edge of the sheet refers to the end on the side opposite to the sheet conveyance (paper discharge) direction.

[0012] The image forming apparatus B is configured to feed a sheet from the paper feeding unit 1 to the image forming unit 2, print an image on the sheet by the image forming unit 2, and then discharge the sheet from the discharge port 3. In the paper feeding unit 1, sheets of a plurality of sizes are stored in the paper feed cassettes 1a and 1b, and the designated sheets are separated one by one and fed to the image forming unit 2. The image forming unit 2 includes, as an example, an electrostatic drum 4, a printing head (not shown) disposed around the electrostatic drum 4, a developing device 6, a fixing device 8, and the like. Image formation on the sheet is performed by forming an electrostatic latent image on the electrostatic drum 4, attaching toner thereto by the developing device 6, transferring the image onto the sheet by a transfer charger (not shown), and heat-fixing the image by the fixing device 8. The sheet on which the image has been formed in this way is sequentially discharged from the discharge port 3 toward the sheet processing device C. In the circulation path 9, the sheet printed on the front side from the fixing device 8 is reversed front to back via the switchback path 10 and then fed again to the image forming unit 2. Thereby, printing can be performed on both the front and back sides of the sheet. The sheet thus double-sided printed is reversed front to back by the switchback path 10 and then discharged from the discharge port 3 toward the sheet processing device C.

[0013] In the image reading device 11, the original sheet set on the platen 12 is scanned by the scanning unit 13 and electrically read via the photoelectric conversion element 14. The read image data is digitally processed and the like by an image processing unit (not shown). In the original sheet feeding device 15, the original sheet set on the stack tray 16 is fed to the platen 12.

[0014] The image forming apparatus B having the above configuration is provided with a control unit (not shown), and printing conditions such as image forming conditions, for example, sheet size designation, color / monochrome printing designation, number of printed copies designation, single-sided / double-sided printing designation, enlargement / reduction printing designation, and the like are set.

[0015] The sheet processing apparatus C of the present invention includes normal paper discharge means for directly discharging a sheet carried in from the carry-in port 22 via the carry-in roller pair 23, post-processing means disposed on one end side of the stacking tray 37 for stapling the sheets stacked on the stacking tray 37, and control means for controlling the post-processing and paper discharge of the sheets. The normal paper discharge means discharges the sheet on which an image has been formed by the image forming apparatus B by designating either the first paper discharge tray 21a or the second paper discharge tray 21b. As the post-processing means of the present embodiment, a staple unit 30 is provided. After bundling a plurality of sheets on which an image has been formed by the image forming apparatus B and performing processing such as staple binding, the sheets are discharged to the second paper discharge tray 21b.

[0016] A conveyance path extends from the carry-in port 22 toward the downstream side in the sheet conveyance direction. This conveyance path branches via a flapper (not shown) into a first paper discharge path 28 leading to the upper first paper discharge tray 21a and a second paper discharge path 29 leading to the lower second paper discharge tray 21b. A first paper discharge roller pair 25 is disposed at the downstream end of the first paper discharge path 28.

[0017] As shown in FIGS. 2 and 3, on the downstream side of the discharge port 35 of the second paper discharge path 29, an inversion conveyance mechanism 40 is provided for switchback conveying the sheet discharged via the second paper discharge roller pair 27 in the paper discharge direction toward the second paper discharge tray 21b and the non-paper discharge direction toward the stacking tray 37. Above the stacking tray 37, a sheet guide portion 50 is provided, which includes a sheet dropping portion 60 having a plurality of sheet dropping members 51 for dropping the inversion-conveyed sheets into the stacking tray 37 for accommodation, and a sheet alignment portion 61 for aligning the width direction of the sheets on the stacking tray 37.

[0018] The sheet dropping member 51 has a plate-shaped main body portion 51a extending in the vertical direction and a pressing portion 51b extending in an L-shaped cross section from the lower end of the main body portion 51a. A plate-shaped gear (rack) 56 is provided in the vertical direction on the main body portion 51a, and the plate-shaped gear (rack) 56 is vertically movable between a position above the second paper discharge roller pair 27 and a contact position where the pressing portion 51b contacts the sheet on the stacking tray 37 by the rotation of a cylindrical gear (pinion) 57 rotatably supported by the support plate 50a. The vertical movement of the sheet dropping member 51 is configured to be a linear movement, and it can drop the sheet onto the stacking tray 37 more quickly and press a wider area of the sheet than an operation of dropping (pressing) the sheet using a rotating member as disclosed in Patent Document 1.

[0019] The inversion conveyance mechanism 40 includes a lifting roller 41 that moves up and down between an engagement position where it engages with the sheet conveyed to the stacking tray 37 and a standby position spaced apart therefrom, and a paddle rotating body 42 that feeds the sheet in the non-paper discharge direction. The lifting roller 41 and the paddle rotating body 42 are attached to a swing bracket 43. A lifting motor (not shown) is connected to the swing bracket 43 to move the mounted lifting roller 41 and paddle rotating body 42 up and down between an engagement position where they engage with the sheet and a standby position spaced apart from the sheet.

[0020] A drive motor (not shown) is connected to the lifting roller 41 and the paddle rotating body 42, and the drive is transmitted so that the lifting roller 41 rotates in the forward and reverse directions and the paddle rotating body 42 rotates in the reverse direction (opposite to the paper discharge direction). A driven roller 48 that conveys the sheet by being in pressure contact with the lifting roller 41 is disposed on the downstream side of the stacking tray 37.

[0021] FIG. 4 shows the configuration of the support plate 54 on which a plurality of sheet dropping members 51 are arranged, as viewed from the back side in the sheet conveying direction. On the support plate 54, a plurality of sheet dropping members 51 are symmetrically arranged with respect to the center line O in the sheet conveying direction. The three sheet dropping members 51A, 51B, and 51C at the center portion 52 are connected to a common rotating shaft 63 with respect to their respective pinions 57. Also, the two sheet dropping members 51D and 51E at the side portion 53 are connected to a common rotating shaft 64 with respect to their respective pinions 57. The rotating shafts 63 and 64 are connected to a drive motor 55 via an electromagnetic clutch 65. The electromagnetic clutch 65 includes a mechanism for rotating only the rotating shaft 63 forward or backward and a mechanism for rotating the rotating shaft 63 and the rotating shaft 64 forward or backward simultaneously. Thereby, it is possible to selectively operate to move three sheet dropping members (51A, 51B, 51C) or five sheet dropping members (51A, 51B, 51C, 51D, 51E) by the forward or backward operation of one drive motor 55. Also, each sheet dropping member 51 is biased by an elastic member such as a spring member at the upper end side to the support plate 54, so that after the sheet dropping operation is completed, it can quickly return to the original standby position. In the present embodiment, the vertical driving of the sheet dropping member 51 is configured as the above-described rack-pinion mechanism, but it may be reciprocated vertically using a timing belt.

[0022] FIG. 5 shows the configuration of the sheet guide portion 50 in a planar view, where the left side in the figure is the downstream side in the sheet conveyance direction, and the right side in the figure is the upstream side in the sheet conveyance direction. The sheet guide portion 50 includes a sheet dropping portion 60 composed of the plurality of sheet dropping members 51, a sheet aligning portion 61 for aligning the width direction of the sheet dropped onto the stacking tray 37, and a rear end regulating portion 38 for regulating the rear end in the length direction of the sheet. The sheet dropping portion 60 is composed of three sheet dropping members 51A, 51B, and 51C arranged at the center portion 52, and two sheet dropping members 51D and 51F arranged at the left and right side portions 53 sandwiching the center portion 52. For the first size sheet smaller than the predetermined size, the sheet dropping members 51A, 51B, and 51C at the center portion 52 are corresponding, and for the second size sheet equal to or larger than the predetermined size, the sheet dropping members 51A, 51B, and 51C at the center portion 52 and the sheet dropping members 51D and 51F at the side portions 53 are corresponding.

[0023] The sheet aligning portion 61 has a pair of aligning plates 62 that are slidably movable in directions approaching and separating with respect to the width direction of the sheet with reference to the center line O. As shown in FIG. 3, the pair of aligning plates 62 project upward from the stacking surface 37a of the stacking tray 37 and are arranged to face each other toward the side edges in the width direction of the sheet, and move in accordance with the width direction of sheets of various sizes conveyed onto the stacking tray 37. In the embodiment shown in FIG. 5, it corresponds to a first size sheet S1 with a sheet width direction less than the predetermined size and a second size sheet S2 with a sheet width direction equal to or greater than the predetermined size. Both the sheet S1 and the sheet S2 are standby at positions (standby positions SP1, SP2) at a distance L slightly separated outward in the sheet width direction. Then, after the sheet is dropped onto the stacking tray 37 by the predetermined sheet dropping member 51 and the rear end of the sheet abuts against the rear end regulating portion 38, the pair of aligning plates 62 move from the standby positions SP1, SP2 to aligning positions AP1, AP2 that sandwich the sheet, respectively.

[0024] The driving switching of the sheet discharging members of the center portion 52 and the side portions 53 is performed by a control unit provided in the image forming apparatus A, and is based on discriminating the size in the sheet width direction based on the sheet size information and on this discrimination result.

[0025] When a sheet is carried out from the discharge port 35, the sheet discharging member 51 waits at a retracted position spaced upward from the stacking tray 37 as shown in FIG. 6(a). Then, as shown in FIG. 6(b), after the rear end of the sheet has passed through the discharge port 35, the sheet is dropped into the stacking tray 37 from the rear end side and accommodated. The drive motor 55 shown in FIG. 4 is driven according to the timing of dropping the rear end of the sheet from the discharge port 35 to the stacking tray 37, and the drive is transmitted to a predetermined sheet discharging member 51 via the transmission mechanism 54. By this drive, after the sheet has fallen onto the stacking tray 37, the sheet discharging member 51 descends, and the pressing portion 51b presses the upper surface of the dropped sheet. Thereby, it is possible to correct the deflection of the sheet on the stacking tray 37.

[0026] Next, the sheet alignment process will be described with reference to FIGS. 7, 8, and 9. As shown in FIGS. 7 and 8, the movement range of the pair of alignment plates 62 overlaps with a part of the position where the sheet dropping member 51 contacts the sheet. FIG. 7 shows the alignment operation of a sheet S1 of a first size smaller than a predetermined size. When the sheet sensor SEN1 detects that the sheet S1 has been discharged from the second paper discharge roller pair 27 to the discharge port 35 (FIG. 9 (ST01)), and it is determined that the sheet S1 is of the first size (FIG. 9 (ST02)), the pair of alignment plates 62 moves from the home position HP to the first standby position SP1 (FIG. 7(a), FIG. 9 (ST11)). This first standby position SP1 is set at a distance L (about 5 mm) outside the width size Sd1 of the sheet S1. Then, when the sheet S1 is conveyed to the stacking tray 37, the sheet dropping member of the center portion 52 is lowered to press the sheet S1 onto the stacking tray 37 (FIG. 7(b), FIG. 9 (ST12)). This pressing operation is performed by lowering the pressing portion 51b of the sheet dropping member 51 so as to contact the upper surface of the stacking tray 37 with the sheet S1 sandwiched therebetween. In this way, when the pressing of the sheet S1 onto the stacking tray 37 is completed, the sheet dropping member 51 rises (FIG. 9 (ST13)), and at the same time, the pair of alignment plates 62 moves from the standby position SP1 to the alignment position AP1 that sandwiches the sheet S1 to complete the alignment operation (FIG. 7(c), FIG. 9 (ST14)).

[0027] FIG. 8 shows the alignment operation of the sheet S2 of the second size equal to or larger than a predetermined size. When the sheet sensor SEN1 detects that the sheet S2 has been discharged from the second pair of paper discharge rollers 27 to the discharge port 35 (FIG. 9 (ST01)) and determines that the sheet S2 is of the second size (FIG. 9 (ST02)), the pair of alignment plates 62 move from the home position HP to the second standby position SP2 (FIG. 8(a), FIG. 9 (ST21)). This second standby position SP2 is set at a distance L (about 5 mm) outside the width size Sd2 of the sheet S2. Then, when the sheet is conveyed to the stacking tray 37, the sheet dropping members of the center portion 52 and the side portion 53 are simultaneously lowered to press the sheet onto the stacking tray 37 (FIG. 8(b), FIG. 9 (ST22)). This pressing operation is performed by lowering the pressing portion 51b of the sheet dropping member 51 so as to contact the upper surface of the stacking tray 37 with the sheet S2 sandwiched therebetween. In this way, when the pressing of the sheet S2 onto the stacking tray 37 is completed, the sheet dropping members 51 of the center portion 52 and the side portion 53 are simultaneously raised (FIG. 9 (ST23)), and the pair of alignment plates 62 move from the standby position SP2 to the alignment position AP2 that sandwiches the sheet S2, completing the alignment operation (FIG. 8(c), FIG. 9 (ST24)).

[0028] As shown in FIGS. 7 and 8, since only the sheet dropping members within the range corresponding to the width size of the conveyed sheet can be lowered, the sheet dropping members in other ranges do not interfere with the pair of alignment plates 62. As a result, before the sheet dropping operation by the sheet dropping members, the pair of alignment plates 62 can be moved to the standby positions SP1 and SP2 set near the outside in the width direction of the sheet. Then, after the sheet dropping operation, the pair of alignment plates 62 can be quickly moved from the standby positions SP1 and SP2 to the alignment positions AP1 and AP2 that align the width direction of the sheet. In this way, the standby positions of the pair of alignment plates 62 are always constant at the sheet width size + a predetermined L width regardless of the sheet size. In particular, for the first size sheet shown in FIG. 7, the moving distance to the alignment position AP1 can be significantly shortened, and the speed of the alignment operation can be increased.

Explanation of Signs

[0029] An image forming system B image forming apparatus C sheet processing apparatus 1 Paper feeding unit 2 Image forming unit 3 Discharge port 10 Switchback path 11 Image reading device 15 Original document feeder 21a First paper discharge tray 21b Second paper discharge tray 22 Inlet 23 Inlet roller pair 25 First paper discharge roller pair 27 Second paper discharge roller pair 28 First paper discharge path 29 Second paper discharge path 35 Outlet 37 Loading tray 37a Loading surface 38 Rear end regulating part 40 Reverse conveyance mechanism 41 Lifting roller 42 Paddle rotating body 43 Oscillating bracket 48 Driven roller 50 Sheet guide part 51 Sheet dropping member 51a Main body part 51b Pressing part 52 Center part 53 Side part 54 Support plate 55 Driving motor 56 Rack 57 Pinion 60 Sheet dropping part 61 Sheet alignment part 62 Alignment plate 63 Rotating shaft 64 Rotating shaft 65 Electromagnetic clutch

Claims

1. A sheet processing apparatus comprising: a pair of discharge rollers for discharging a sheet; a stacking tray on which the sheet discharged by the pair of discharge rollers is stacked; a sheet dropping member for dropping the sheet discharged by the pair of discharge rollers onto the stacking tray; and a sheet guide unit having a pair of alignment members that abut against and align with the side edges in the width direction of the sheet stacked on the stacking tray. The sheet dropping member is provided in plurality along the width direction of the sheet above the stacking tray. The moving range of the pair of alignment members and a part of the position where the sheet dropping member contacts the sheet overlap. A sheet processing apparatus that drops a sheet onto a stacking tray by lowering any one of a plurality of sheet dropping members according to the size in the width direction of the sheet discharged by the pair of discharge rollers.

2. The sheet guide unit has a center portion where the sheet dropping member is disposed at the center in the width direction of the sheet, and a pair of side portions sandwiching the center portion. The sheet processing apparatus according to claim 1, further comprising: first driving means for vertically driving only the sheet dropping member of the center portion according to the size in the width direction of the sheet; and second driving means for vertically driving the sheet dropping members of both the center portion and the pair of side portions simultaneously.

3. The pair of alignment members move to a standby position set near the outer side in the width direction of the sheet before the sheet dropping operation by the sheet dropping member, and move to an alignment position for aligning the width direction of the sheet after the sheet dropping operation. The sheet processing apparatus according to claim 1.

4. The sheet dropping member is arranged to be vertically movable by a rack and a pinion, and is biased upward via an elastic member. The sheet processing apparatus according to claim 1.

Images