JP4508399B2 - Sheet processing apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet processing apparatus for aligning or stapling sheets discharged from an image forming apparatus such as a copying machine or a printer, and more particularly, to appropriately perform a stacking operation of sheet bundles to be discharged.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been proposed a sheet processing apparatus that performs various post-processing such as alignment, stapling, and punching on a sheet discharged from an image forming apparatus such as a copying machine or a printer, or a sheet bundle stacked on a plurality of sheets. In such an apparatus, discharged sheets and the like are once discharged and stacked on a processing tray, and after processing such as alignment and stapling, the sheets are discharged to a stack tray as a sheet stacking means by a sheet bundle discharging means.
[0003]
When aligning sheets on the processing tray, in order to make the length of the processing tray longer than the center of gravity of the sheets during alignment, the lower and upper sides of the sheet bundle being aligned are guided by projecting the intrusion tray provided below the processing tray. Yes. Here, when projecting the in / out tray, it is necessary to avoid interference with the sheet bundle already discharged onto the stack tray. For this reason, when the sheet upper surface detection means detects that the sheet upper surface on the stack tray is equal to or higher than a predetermined height, the stack tray is lowered so that the intrusion tray protrudes after the sheet upper surface is below a predetermined position. It is composed.
[0004]
On the other hand, when there are a large number of sheet bundles to be discharged to the stack tray, there is a problem that feeding failure occurs due to buckling of the discharged sheet bundle. Therefore, the stack tray is raised when the sheet bundle is discharged, and the drop height of the processing tray and the stack tray is reduced.
[0005]
[Problems to be solved by the invention]
However, in the sheet processing apparatus configured as described above, when a large number of sheet bundles are discharged onto the stack tray, as described above, it is necessary to lower the stack tray and then project the protrusion / distraction tray. For this reason, it takes time until the protruding / extracting tray is protruded, the sheet alignment failure occurs in time for the next sheet alignment on the processing tray to be started, or the trailing edge is not loaded due to a shortage of discharged bundles. There was a risk of catching on the discharge roller and causing a discharge failure.
[0006]
Therefore, the present invention prevents the trailing edge discharge failure of the discharge bundle and operates the tray tray to start the sheet alignment by operating the sheet stacking unit so that the upper surface of the stacked sheets is below a predetermined position in a substantially constant short time. An object of the present invention is to provide a sheet processing apparatus that can protrude forward.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, a typical configuration of a sheet processing apparatus and an image forming apparatus according to the present invention includes a sheet bundle discharge unit that discharges a bundle of conveyed sheets, and a bundle discharged by the sheet bundle discharge unit. A sheet stacking unit that can stack a sheet bundle and is movable in the vertical direction, a driving unit that drives the sheet stacking unit, and a stacking surface of the sheet stacking unit or an upper surface of the stacked sheet bundle at a predetermined position. And when the sheet bundle is ejected by the sheet bundle ejecting means and stacked on the sheet stacking means, the driving means is configured such that the number of sheets of the ejected bundle is equal to or less than a predetermined number. If the case of, based on the detection result of the sheet upper surface detection means, together to wait the sheet stacking means to the predetermined position, the number of sheets of the bundle to be discharged is more than a predetermined number Is pre SL raises the sheet stacking means to a higher corrected position than the predetermined position, before the end bundle discharge, the cause from the corrected position is lowered the sheet stacking means, the sheet upper surface detection means starts detection The amount of lowering of the sheet stacking means that is lowered before the end of the bundle discharge is made variable so that the time from the detection of the sheet upper surface to the detection of the sheet upper surface becomes substantially constant regardless of the number of discharged sheets .
[0008]
With the above configuration, when the sheet bundle is discharged onto the sheet stacking unit, the sheet stacking unit is positioned according to the number of sheet bundles and the thickness of the sheet bundle before the sheet upper surface detecting unit detects that the sheet upper surface is at a predetermined position. By lowering the fixed amount, the drop height from the sheet bundle discharging unit to the sheet stacking unit, that is, the sheet stackable amount can be increased, and discharge failure at the rear end portion of the discharge bundle can be prevented.
[0009]
In addition, the time until the detection of the upper surface of the discharged sheet bundle is substantially constant regardless of the number of sheets and the sheet thickness, so that the protrusion timing of the protruding and retracting tray is also substantially constant, thereby preventing sheet misalignment. It becomes possible.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a sheet processing apparatus and an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the overall configuration of the sheet processing apparatus, FIG. 2 is a diagram for explaining the configuration in the vicinity of the processing tray, FIG. 3 is a control block diagram of the sheet stacking means, and FIGS. FIG. 6 is a diagram showing the sheet stacking means in the normal stacking position, FIG. 7 is a diagram showing the sheet stacking means in the correction position, FIG. 8 is a diagram showing the sheet stacking means lowered before the end of discharging, and FIG. FIG. 1 is an overall configuration diagram of an image forming apparatus.
[0011]
(Image forming device)
First, referring to FIG. 9, an image forming apparatus provided with a sheet processing apparatus according to the present invention will be described using a copying machine as an example. An image reading unit including a platen glass 906, a light source 907, a lens system 908, and an automatic document feeder 500 that feeds a document to the platen glass 906 is configured in the upper part of the image forming apparatus main body 300. The image forming apparatus main body 300 includes a feeding unit 909 and an image forming unit 902. Further, on the side of the image forming apparatus main body 300, a finisher 1 and the like are provided as a sheet processing apparatus for stacking sheets on which images have been discharged from the copying machine main body.
[0012]
The feeding unit 909 includes cassettes 910 and 911 that store recording sheets P and are detachable from the image forming apparatus main body 300, and a deck 913 disposed in a pedestal 912. The image forming unit 902, which is an image forming unit, includes a cylindrical photosensitive drum 914 and a developing device 915 around it, a transfer charger 916, a separation charger 917, a cleaner 918, a primary charger 919, and the like. ing. A conveyance device 920, a fixing device 904, a discharge roller pair 399, and the like are disposed on the downstream side of the image forming unit 902.
[0013]
When an image is formed, first, when a feeding signal is output from the control device 930 provided in the image forming apparatus main body 300, the sheet P is fed from the cassette 910, 911 or the deck 913. On the other hand, the light reflected from the light source 907 on the document D placed on the platen glass 906 is irradiated onto the photosensitive drum 914 via the lens system 908. The photosensitive drum 914 is uniformly charged in advance by a primary charger 919, and an electrostatic latent image is formed by irradiation with light, and then the electrostatic latent image is developed by a developing device 915 to form a toner image. It is formed.
[0014]
The sheet P fed from the feeding unit 909 is corrected in skew by the registration roller pair 901, and further sent to the image forming unit 902 at the same timing. In the image forming unit 902, the toner image on the photosensitive drum 914 is transferred to the sheet P by the transfer charger 916. The sheet P to which the toner image has been transferred is charged to a polarity opposite to that of the transfer charger 916 by the separation charger 917 and separated from the photosensitive drum 914. The separated sheet P is conveyed to the fixing device 904 by the conveying device 920, and the transferred image is permanently fixed by applying heat and pressure. The sheet P on which the image is fixed is discharged from the image forming apparatus main body 300 by the discharge roller pair 399 and is sent to the finisher 1.
[0015]
(Sheet processing equipment)
A finisher 1 that is a sheet processing apparatus is disposed on the side of the image forming apparatus main body 300 as shown in FIG. 1, and is aligned with a sheet discharged from the image forming apparatus main body 300 or a sheet bundle stacked on a plurality of sheets. Various post-treatments such as stapling and punching are performed.
[0016]
As shown in the figure, the finisher 1 has an inlet roller pair 2 at a position facing the discharge roller pair 399 of the image forming apparatus main body 300, followed by a conveying roller 3, a sheet detection sensor 31, and a sheet to be conveyed. A punch unit 50 for making a hole in the rear end, a large conveying roller 5, and pressing rollers 12, 13 and 14 for pressing the sheet against the large conveying roller 5 are provided.
[0017]
A switching flapper 11 is provided along the large conveying roller 5 to switch between the non-sorting path 21 and the sorting path 22. The switching flapper 10 switches the sort path 22 and the buffer path 23 for temporarily storing sheets. The non-sort path 21 is provided with a discharge roller 9 and discharges the sheet to the sample tray 201.
[0018]
From the sort path 22, a transport roller 6, a processing tray 130 for temporarily stacking and aligning sheets, a discharge roller 7 for discharging the sheets to the processing tray 130, a stapling unit 101 for stapling the sheets on the processing tray 130, A swing guide 150, a bundle discharge roller pair 180 as sheet bundle discharge means, and the like are provided. The bundle discharge roller pair 180 includes a roller 180a disposed on the processing tray 130 and a roller 180b supported by the swing guide 150, and cooperates when the swing guide 150 is closed. The upper sheet bundle is nipped and conveyed, and the bundle is discharged onto a stack tray 200 as sheet stacking means.
[0019]
A configuration near the processing tray 130 will be described with reference to FIG. In the vicinity of the processing tray 130, a rear end stopper 131 disposed at the rear end of the processing tray 130, an alignment means 140 for aligning sheets on the processing tray 130, a swing guide 150 swinging above the processing tray 130, and a discharge A pull-in paddle 160 for returning the sheet discharged from the roller 7 to the rear end stopper 131, an in / out tray 170 disposed below the processing tray 130, and a bundle discharge roller pair 180 are provided.
[0020]
The processing tray 130 is an inclined tray with the downstream side (left side in the figure) upward and the upstream side (right side in the figure) downward, and the rear end stopper 131 is fitted to the lower end. The sheet discharged from the discharge roller 7 slides on the processing tray 130 until its rear end comes into contact with the rear end stopper 131 due to its own weight and the action of the paddle 160. The rear end stopper 131 rotates and retracts below the processing tray 130 when stapling is performed by the staple unit 101.
[0021]
The swing guide 150 is pivotally supported by the swing support shaft 151 on the upstream side (right side in the figure), and swings by the action of the rotating cam 152 connected to the motor M150. When the sheet is discharged to the processing tray 130, the swing guide 150 is in an open state (the bundle discharge roller pair 180 is separated), and does not hinder sheet discharge and alignment. When the sheet bundle is discharged from the processing tray 130, the sheet bundle is rotated and closed, and the sheet bundle is nipped and conveyed by the roller 180b provided on the downstream side (left side in the drawing) and the roller 180a provided on the processing tray 130. To do. The rollers 180a and 180b of the bundle discharge roller pair 180 can be rotated forward and backward by receiving a drive from the motor M180.
[0022]
The in / out tray 170 is located below the processing tray 130, protrudes from the lower side of the roller 180a, and advances and retreats in the sheet conveyance direction (arrow x direction) while following the inclination of the processing tray 130 substantially. In the protruding state, the tip / out tray 170 overlaps the stack tray 200 side, and in the retracted state, the tip retracts inward from the bundle discharge roller pair 180. The leading end in the protruding state is set to be positioned downstream of the center of gravity of the sheet placed on the processing tray 130.
[0023]
As shown in FIG. 1, the stack tray 200 and the sample tray 201 have motors M200 and M201 as drive means so that both can move independently in the vertical direction. The apparatus main body includes a sheet upper surface detection sensor 204 that is a sheet upper surface detection unit that detects a sheet surface on the sample tray 201, a sheet upper surface detection sensor 205 that is a sheet upper surface detection unit that detects a sheet surface on the stack tray 200, and others. Each sensor is provided.
[0024]
The sample tray 201 can move from the sheet upper surface detection sensor 204 to the sheet upper surface detection sensor 205, but its upper limit is restricted by the upper limit sensor 203a disposed in the vicinity of the discharge roller 9, and is disposed at a position corresponding to the stacking of 1000 sheets. The loading capacity is limited by the lower limit sensor 203b. The stack tray 200 can move from the sheet upper surface detection sensor 205 to the lower limit sensor 203e. However, in order to limit the stacking amount by the height, the sensor 203c is positioned at a position corresponding to 1000 sheets and the sensor 203d is positioned at a position corresponding to 2000 sheets. Is arranged. Each tray is provided with a sheet presence / absence detection sensor 206.
[0025]
The sample tray 201 and the stack tray 200 normally stand by at the position of the sheet upper surface detection sensors 204 and 205. A stack tray 200 normally stacks the discharged sheets, and can receive a bundle processed by the staple unit 101 or a bundle that is unbound and discharged by a small number of sheets. Can be loaded. If the output still continues at this time, the stack tray 200 is further lowered to a sensor 203d 'disposed below by an amount equivalent to 1000 sheets, the sample tray 201 is lowered to the sheet upper surface detection sensor 205 for the processing tray 130, and further discharged. Can continue.
[0026]
As shown in FIG. 3, a control device 4 (see FIG. 1) for controlling the operation of the finisher 1 is connected to the motor M200 that drives the stack tray 200. From the sheet upper surface detection sensor 205 and other sensors. It is driven based on the signal. Further, the control device 4 is connected to the control device 930 of the image forming apparatus main body 300 by the communication means 932.
[0027]
As a method of detecting the sheet surface by the sheet upper surface detection sensors 204 and 205, the optical axes of the sheet upper surface detection sensors 204 and 205 come above each tray or a predetermined amount (here, 1 mm) above the uppermost surface of the sheet bundle on each tray. Such a state is an initial state, and after the sheets are stacked, the sheet is repeatedly lowered by a predetermined amount until the covered optical axis of the sheet upper surface detection sensor appears.
[0028]
(Batch discharge operation)
Next, an operation at the time of discharging the bundle using the processing tray 130 will be described. As shown in FIG. 4A, the sheet that has passed through the large conveying roller 5 is sent to the sort path 22 by the switching flapper 10, discharged onto the processing tray 130 by the discharge roller 7, and sequentially stacked by the paddle 160. At this time, the in / out tray 170 is in a protruding state, preventing the leading end of the stacked sheets from hanging down and causing a return failure, and improving the alignment of the sheets on the processing tray 130. When a predetermined number of sheets are stacked and aligned on the processing tray 130, the swing guide 150 is lowered as shown in FIG. 4B, and the roller 180b is placed on the sheet bundle. At this time, stapling is performed by the staple unit 101 as necessary.
[0029]
Then, as shown in FIG. 5A, the bundle discharge roller pair 180 rotates, and the sheet bundle P0 is discharged to the stack tray 200. At this time, in order for the sheet tray 170 to drop the sheet bundle onto the stack tray 200, the sheet bundle is retracted before the sheet bundle passes through the bundle discharge roller. When the sheet bundle P0 is stacked on the stack tray 200 as shown in FIG. 5B, the stack tray 200 is lowered until the sheet surface is detected by the sheet upper surface detection sensor 205. When the upper surface of the stacked sheets falls below a predetermined position, the retracting tray 170 is in a protruding state to support the next sheet to be discharged.
[0030]
As shown in FIG. 6, when the number of sheets discharged by the bundle discharge roller pair 180 is equal to or less than a predetermined number (for example, 5 or less in this embodiment), the stack tray 200 is in the normal stacking position. It waits at the position of the sheet upper surface detection sensor 205. There is a normal drop L0 between the sheet bundle P0 discharged at this time and the stack tray 200.
[0031]
As shown in FIG. 7, when the number of bundles discharged is equal to or greater than a predetermined number, the stack tray 200 is driven by the motor M200 under the control of the control device 4 (see FIG. 3), and rises a predetermined amount before discharging the bundles. Then, it stops at the correction position shown in the figure. The predetermined amount to be increased is controlled by the control device 4 of the finisher 1 according to the set number of sheets input by the user operating the sheet number setting unit 931 connected to the control device 930 of the image forming apparatus main body 300, for example. There is a small drop L1 between the sheet bundle P0 discharged at this time and the stack tray 200. This prevents the leading end of the discharged sheet bundle from abutting against the already stacked sheet bundle and curling, and prevents the bottom sheet of the discharged sheet bundle from buckling due to a drop. Can do.
[0032]
On the other hand, if the stack discharge is completed while the stack tray is moved (raised) to the position shown in FIG. 7, the sheet bundle may be thicker than the small drop L1, and the bundle discharge roller pair 180 may receive the sheet bundle. There is a risk that the rear end may be caught, resulting in poor loading. Further, when the sheet upper surface detection operation is performed after the bundle is discharged, the stack tray 200 is lowered until the optical axis of the sheet upper surface detection sensor 205 appears as described above, so the height L2 shown in FIG. 8 is lowered. Time is required. Here, as described above, the intrusion tray 170 cannot be protruded until the sheet upper surface detection sensor 205 is not covered with the sheet. Therefore, when the height L2 is large, the next sheet is discharged to the processing tray 130. In some cases, the protrusion of the in / out tray 170 may not be in time, resulting in poor alignment on the processing tray 130.
[0033]
Therefore, the stack tray 200 is at the correction position raised as shown in FIG. 7 when the bundle discharge is started, but after the bundle discharge is started and before the end, a predetermined amount of the sheet bundle (in this embodiment, 100 mm). By dropping a predetermined amount at the time of conveyance, a head required for stacking is secured.
[0034]
The predetermined amount to be lowered is variable according to the set number of sheets input from the sheet number setting unit 931, so that the time required for detecting the sheet upper surface after discharging the bundle is set to a substantially constant short time regardless of the number of sheet bundles. The protrusion timing of the raising / lowering tray 170 that operates after the sheet upper surface detection operation is determined can also be made substantially constant. In this embodiment, the upper surface of the sheet after discharging the sheet bundle is set to be about 3 mm above the sheet upper surface detection sensor 205 (height L2 shown in FIG. 8).
[0035]
Further, the predetermined amount to be lowered may be variable according to the thickness of the sheet bundle detected by a swing guide opening amount detection sensor (not shown) provided in the swing guide 150. This makes it possible to control the height more accurately than depending on the number of sheets.
[0036]
In the present embodiment, the stack tray 200 has been described to be raised before the bundle discharge. However, even if the stack tray 200 is not lifted, the stack tray 200 is moved according to the number and thickness of the sheet bundle before the bundle discharge is finished. By lowering the sheet by a predetermined amount, it is possible to make the sheet upper surface detection operation and the protruding timing of the retracting tray 170 substantially constant.
[0037]
【The invention's effect】
As described above, in the sheet processing apparatus and the image forming apparatus according to the present invention, when the sheet bundle is discharged and stacked on the sheet stacking unit, the sheet is discharged between the start and the end of the discharge. By lowering the stacking means and making the lowering amount variable according to the number or thickness of the discharged sheet bundle, the upper surface of the stacked sheets can be kept below a predetermined position in a substantially constant short time. As a result, the drop height from the sheet bundle discharging means to the sheet stacking means is increased to prevent the trailing edge discharge failure of the discharged bundle, and the time required for detecting the sheet upper surface can be made substantially constant. However, it is possible to prevent misalignment of the next sheet discharged to the processing tray.
[Brief description of the drawings]
FIG. 1 is a front view illustrating an overall configuration of a sheet processing apparatus.
FIG. 2 is a diagram illustrating a configuration near a processing tray.
FIG. 3 is a control block diagram of a sheet stacking unit.
[Fig. 4]
FIG. 5 is a diagram illustrating a bundle discharging operation.
FIG. 6 is a diagram illustrating a sheet stacking unit in a normal stacking position.
FIG. 7 is a diagram illustrating a sheet stacking unit at a correction position.
FIG. 8 is a diagram illustrating a sheet stacking unit that is lowered before the end of discharging.
FIG. 9 is an overall configuration diagram of an image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Finisher 2 ... Inlet roller pair 3 ... Conveyance roller 4 ... Control apparatus 5 ... Conveyance large roller 6 ... Conveyance roller 7 ... Discharge roller 9 ... Discharge roller
10 ... Switching flapper
11 ... Switching flapper
12… press roller
13… Pressing roller
14… Pressing roller
21… Non-sort path
22… Sort path
23… buffer path
31… Seat detection sensor
50… Punch unit
101… Staple unit
130… processing tray
131… Rear end stopper
140… alignment method
150… Oscillating guide
151… Oscillating fulcrum shaft
152… Rotating cam
160… paddle
170… Infestation tray
180 ... Bundle discharge roller pair
180a ... Roller
180b ... Roller
200 ... Stack tray
201… Sample tray
203a ... Upper limit sensor
203b ... Lower limit sensor
203c Sensor
203d Sensor
203e ... Lower limit sensor
204… Seat upper surface detection sensor
205… Seat upper surface detection sensor
206… Seat presence / absence detection sensor
300 ... Image forming apparatus main body
399… discharge roller pair
500 ... Automatic document feeder
901… Registration roller pair
902 ... Image forming unit
904. Fixing device
906… Platen glass
907… Light source
909… Feeding department
910… cassette
911… cassette
912… Pedestal
913… deck
914 ... Photosensitive drum
915… Developer
916… Transfer charger
917… Separation charger
918… cleaner
919… Primary charger
920 ... Conveying device
930… Control device
931 ... Sheet number setting means
932… Communication means

Claims (6)

Sheet bundle discharging means for discharging a bundle of conveyed sheets;
A sheet stacking unit capable of stacking the sheet bundle discharged by the sheet bundle discharging unit and movable in the vertical direction;
Driving means for driving the sheet stacking means;
Sheet upper surface detection means for detecting the loading surface of the sheet stacking means or the upper surface of the stacked sheet bundle at a predetermined position;
When the sheet bundle is discharged by the sheet bundle discharge means and stacked on the sheet stacking means, the drive means detects the detection result of the sheet upper surface detection means when the number of discharged sheets is equal to or less than a predetermined number. based on, together to wait the sheet stacking means to the predetermined position, when the number of sheets of the bundle to be discharged is more than a predetermined number raises the sheet stacking means to a higher corrected position than before Symbol predetermined position , Before the end of the bundle discharge, the sheet stacking means is lowered from the correction position ,
The lowering amount of the sheet stacking unit that is lowered before the end of the bundle discharge is set so that the time from when the sheet upper surface detection unit starts detection until the sheet upper surface is detected is substantially constant regardless of the number of discharged sheets. A sheet processing apparatus that is variable . The descending amount of the sheet stacking means is a bundle of sheets to be discharged so that the time from the detection of the sheet upper surface detection means to the detection of the sheet upper surface becomes substantially constant regardless of the number of discharged sheets. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is variable depending on the number of sheets. The descending amount of the sheet stacking means is the thickness of the bundle to be discharged so that the time from the detection of the sheet upper surface detection means to the detection of the sheet upper surface becomes substantially constant regardless of the number of discharged sheets. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is variable depending on the type. 4. The sheet processing apparatus according to claim 1, wherein the lowering operation of the sheet stacking unit is performed before the operation of the sheet upper surface detection unit. The sheet stacking means is disposed in the vicinity of the lower side of the sheet bundle discharging means and is movable substantially parallel to the stacking surface of the sheet stacking means, and supports the lower surface of the sheets discharged by the sheet stacking means. 5. The sheet processing apparatus according to claim 1, further comprising a retractable tray that is movable between a holding position that protrudes into the main body and a retracted position that is retracted into the main body. A sheet processing apparatus according to any one of claims 1 to 5 ,
Image forming means for forming an image on a sheet;
An image forming apparatus comprising: a discharge unit configured to discharge a sheet image-formed by the image forming unit to the sheet processing apparatus.

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