JP4012128B2 - Sheet processing apparatus and image forming apparatus having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet processing apparatus and an image forming apparatus including the sheet processing apparatus, and more particularly to detection of an upper surface of a sheet discharged onto a stack tray after image formation.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, and a facsimile, in order to reduce the labor required for binding processing and the like for sheets such as copy sheets after image formation, the sheets after image formation are sequentially processed. Some sheet processing apparatuses are provided with a sheet processing apparatus that selectively captures the sheet and performs a binding process, a punching process, and the like on the sheet.
[0003]
Here, such a sheet processing apparatus includes a sheet processing mechanism for performing binding processing on sheets, and a plurality of (for example, two) stack trays for stacking a large number of sheets (for example, two sheets) ( For example, see Patent Document 1.)
[0004]
In such a sheet processing apparatus having two stack trays, when the sheet stacking position is changed from the upper stack tray to the lower stack tray, the upper stack tray is placed above the sheet discharge port. At the same time, the lower stack tray is moved upward to stack sheets.
[0005]
In addition, a sheet sensor that detects the sheet stacking surface that is the topmost sheet on the stack tray is provided, and the sheet sensor detects so that the sheet stacked on the stack tray does not block the sheet discharge port. The stack tray was moved based on the result.
[0006]
[Patent Document 1]
JP 2003-002501 A
[0007]
[Problems to be solved by the invention]
However, in the conventional example, when curled sheets are stacked, there is a problem that the upper surface of the stack tray is erroneously detected instead of the upper surface of the stacked paper. This point will be described with reference to FIGS. 15 and 16.
[0008]
15 and 16 show how the upper stack tray 18a in the finisher 119 moves from the upper side to the lower side of the discharge roller pair 560 in order to stack the sheets, and the sheet sensor 3 detects the sheet stacking surface. FIG.
[0009]
The sheet sensor 3 includes a flag (plate member) 11 that is biased toward the outside of the finisher 119 and a detection unit 10 that detects whether or not the flag 11 is pushed into the finisher 119. The uppermost sheet on the upper stack tray 18a is detected.
[0010]
FIG. 15A shows a state in which the upper stack tray 18a is moving downward from the standby position above the sheet discharge port. When the stacked sheets are curled, a gap G is formed between the upper surface of the upper stack tray 18a and the lower surface of the stacked paper as shown in FIG. When the upper stack tray 18a is lowered, the state shown in FIG. 15B is entered, and the detection unit 10 of the sheet sensor 3 is turned on.
[0011]
When the upper stack tray 18a is further lowered and the upper stack tray 18a reaches the position D0 as shown in FIG. 16A, the flag 11 of the sheet sensor 3 rotates in the gap, and the detection unit 10 Will be turned off. Thereafter, as shown in FIG. 16B, when the upper stack tray 18a is lowered by L2, the control circuit determines OFF and stops the lowering operation. Usually L2 = 0.
[0012]
And it raises to the place where the detection part 10 of the sheet sensor 3 becomes ON, and stops. Then, the state shown in FIG. 15B is obtained, and the curled sheet blocks the discharge port. Therefore, there arises a problem that jam occurs and a stacking failure occurs.
[0013]
The present invention has been made paying attention to the above points. When the stack tray is moved to the sheet stacking position, even when curled sheets are stacked, the sheet stacking surface is accurately detected. It is an object of the present invention to provide a sheet processing apparatus that prevents the occurrence of misalignment and stacking failure.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the sheet processing apparatus according to claim 1 is a discharge unit that discharges sheets, a stacking unit that sequentially stacks sheets discharged by the discharge unit, and a drive that raises and lowers the stacking unit. Means, A flag provided at a predetermined height for detecting the stacking means and a sheet on the stacking means, wherein the flag is located at a first position when not contacting the stacking means and the sheet; A flag located at a second position when in contact with the sheet; a detection unit for detecting the position of the flag; Said loading means The Lowering from above the discharge means If you want to let The discharging means From Discharged sheet The detection unit detects that the flag has been displaced from the second position to the first position, rather than lowering the loading means when sequentially loading the loading means located below the discharging means. The descending amount of the loading means from when it was detected is large. Control means for controlling the driving means.
[0018]
Claim 2 The sheet processing apparatus is configured to discharge a sheet, a stacking unit that sequentially stacks the sheets discharged by the discharging unit, a driving unit that raises and lowers the stacking unit, and a sheet on the stacking unit. Sheet detecting means for detecting presence or absence; A flag provided at a predetermined height for detecting the stacking means and a sheet on the stacking means, wherein the flag is located at a first position when not contacting the stacking means and the sheet; A flag located at a second position when in contact with the sheet; a detection unit for detecting the position of the flag; Said loading means The Lowering from above the discharge means Let When The detection unit detects that the flag has been displaced from the second position to the first position when the detection result of the sheet detection means indicates that there is a sheet than when the detection result indicates that there is no sheet. The descending amount of the loading means from when Control means for controlling the driving means.
[0022]
Claim 3 The image forming apparatus according to claim 1, and an image forming unit that forms an image on a sheet; Or 2 And a sheet processing apparatus according to claim 1.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
(Internal structure of copier)
FIG. 1 is a diagram showing a schematic configuration of a copying machine as an example of an image forming apparatus provided with a sheet processing apparatus according to an embodiment of the present invention.
[0025]
In FIG. 1, reference numeral 100 denotes a copying machine, and the copying machine 100 includes an apparatus main body 101 and a finisher 119 which is a sheet processing apparatus. A document feeder 102 is provided on the upper part of the apparatus main body 101. The document D is placed on the document placing unit 103 by the user, and is sequentially separated one by one by the feeding unit 104 and supplied to the registration roller pair 105. Subsequently, the document D is temporarily stopped by the registration roller pair 105, a loop is formed, and skew is corrected. Thereafter, the document D passes through the introduction path 106 and passes through the reading position 108, whereby the image formed on the surface of the document is read. The document D that has passed the reading position 108 passes through the discharge path 107 and is discharged onto the discharge tray 109.
[0026]
When reading both the front and back sides of a document, first, the document D passes through the reading position 108 as described above, whereby an image on one side of the document is read. Thereafter, the document D passes through the discharge path 107, is switched back by the reverse roller pair 110, and is sent again to the registration roller pair 105 in a state where the front and back are reversed.
[0027]
Then, in the same manner as when the image on one side is read, the skew of the original D is corrected by the registration roller pair 105, and the image on the other side is read at the reading position 108 through the introduction path 106. It is done. Then, the document D passes through the discharge path 107 and is discharged to the discharge tray 109.
[0028]
On the other hand, the document passing through the reading position 108 is irradiated with light from the illumination system 111, and then the reflected light reflected from the document is guided to the optical element 113 (CCD or other element) by the mirror 112 to be converted into image data. Converted. A latent image is formed on the photosensitive drum by irradiating the photosensitive drum 114 with laser light based on the image data. Further, thereafter, the latent image formed on the photosensitive drum 114 is developed with toner supplied from a toner supply device (not shown), whereby a toner image is formed on the photosensitive drum.
[0029]
In addition, a sheet such as paper or plastic film stacked on the cassette 115 in accordance with the toner image forming operation is sent out from the cassette 115 according to a recording signal and enters between the photosensitive drum 114 and the transfer device 116. To do. Then, the toner image on the photosensitive drum 114 is transferred to the sheet by the transfer unit 116, and then the toner image is transferred to the sheet on which the toner image is transferred by the heating and pressing of the fixing unit 117 while passing through the fixing unit 117. It is fixed.
[0030]
When images are formed on both sides of the sheet, the sheet on which the image is fixed on one side by the fixing device 117 is switched back by the switchback roller pair 121 through a double-sided path 118 provided on the downstream side of the fixing device 117. The toner image is transferred again between the photosensitive drum 114 and the transfer device 116 of the image forming unit, and the toner image is also transferred to the back surface. Then, the toner image is fixed by the fixing device 117 and is discharged to the outside (finisher 119 side).
[0031]
(Internal structure of finisher)
FIG. 2 is a diagram illustrating the internal configuration of the finisher 119. The finisher 119 sequentially fetches sheets discharged from the apparatus main body 101, aligns a plurality of fetched sheets and bundles them into one bundle, stapling processes that bind the bundled sheet bundles with staples, and the vicinity of the trailing edge of the fetched sheets Each of the sheet processes such as punching, sorting, non-sorting, and bookbinding is performed, and a folding device 400, a processing unit 500, and the like are provided.
[0032]
Here, as shown in the figure, the processing unit 500 is provided downstream of the inlet roller pair 502 for guiding the sheet conveyed from the apparatus main body 101 to the inside, and the sheet is placed in the non-sort mode. And a flapper 551 for leading to the sort path 552 in the sort mode or to the bookbinding path 553 in the folding mode.
[0033]
In the non-sort mode, the sheet guided to the sort path 552 by the flapper 551 is discharged onto the stack trays 18a and 18b by the normal rotation of the discharge roller pair 560 capable of normal and reverse rotation.
[0034]
A punch unit (not shown) for punching near the rear end of the sheet conveyed between the apparatus main body 101 and the finisher 119 can be attached.
[0035]
In the sort mode, the sheets guided to the sort path 552 by the flapper 551 are stacked on an intermediate tray (hereinafter referred to as a processing tray) 630 by reverse rotation after a predetermined amount of normal rotation of the discharge roller pair 560. Is done. The sheets stacked in a bundle on the processing tray 630 are subjected to alignment processing, stapling processing by the stapler 601 and the like as necessary, and then moved up and down by the paper discharge roller pair 560 (self-running). It is discharged onto stack trays 18a and 18b that are configured to be possible.
[0036]
On the other hand, the folding device 400 includes two pairs of staplers 818 as binding means and a pair of folding rollers 826 as folding means for folding a sheet bundle, and sheets from the bookbinding path 553 are stored in a storage guide 820. Thereafter, the sheet is conveyed until the tip comes into contact with a positioning member 823 that is movable in the vertical direction.
[0037]
Here, on the storage guide side of the pair of folding rollers 826, a protruding member 825 as a protrusion means is provided with the storage guide 820 interposed therebetween. The protruding member 825 provided opposite to the folding roller pair 826 is protruded toward the sheet bundle stored in the storage guide 820, whereby the sheet bundle is pushed out to a nip that is a folding portion of the folding roller pair 826. Then, after being folded by the pair of folding rollers 826, it is discharged to the saddle discharge tray 832.
[0038]
(Up and down movement of stack tray)
By the way, as shown in FIG. 2, the upper and lower stack trays 18a and 18b are attached to the finisher body so as to be independently movable in the vertical direction, and the stacker motors 209a and 209b which are moving means inside the stack trays By transmitting the forward / reverse drive to the rack portion (not shown) formed in a part of the column 37 by the pinion gear 225, the stack trays 18a and 18b can be moved up and down independently (up and down). It has become.
[0039]
FIG. 3A is a diagram showing that the upper stack tray 18a is disposed at the sheet stacking position and the lower stack tray 18b is disposed at the initial position. FIG. 3B is a diagram illustrating that the upper stack tray 18a is disposed at the retracted position and the lower stack tray 18b is disposed at the sheet stacking position.
[0040]
In the present embodiment, the upper stack tray 18a, which is the first tray, is movable to a sheet stacking position for stacking sheets discharged from the sheet discharge port 36 and a retreat position above the discharge port 36, and the sheet. After moving to the stacking position, it descends as the number of stacked sheets increases.
[0041]
The lower stack tray 18b, which is the second tray, can move between the initial position HP (see FIG. 3 (a)) and the sheet stacking position (see FIG. 3 (b)). When stacking sheets on the tray 18b, the upper stack tray 18a is moved to the retracted position, and then the lower stack tray 18b is moved to the sheet stacking position.
[0042]
The lower stack tray 18b moves to the sheet stacking position and then descends as the number of stacked sheets increases. Further, when stacking sheets on the upper stack tray 18a that has moved to the retreat position, the lower stack tray 18b is lowered so as not to prevent the upper stack tray 18a from being lowered.
[0043]
Here, in the present embodiment, when the lower stack tray 18b is lowered in accordance with the lowering of the upper stack tray 18a in this way, the lower stack tray 18b is kept waiting above the HP without being lowered to the HP. I am doing so. As a result, when sheets are stacked again on the lower stack tray 18b, the time required to move the lower stack tray 18b to the sheet stacking position can be shortened.
[0044]
On the other hand, a sheet sensor 3 for detecting the uppermost surface of the sheets stacked on the stack trays 18a and 18b is provided at the discharge port 36 for discharging the sheets to the stack trays 18a and 18b, as shown in FIG. The sheet sensor 3 can move the stack trays 18a and 18b to a position where the stacked sheets do not block the discharge port 36.
[0045]
Here, the sheet sensor 3 detects the flag (plate member) 11 urged toward the outside of the finisher 119 as described above, and detection of whether or not the flag 11 is pushed into the finisher 119. The discharge port 36 is not blocked by detecting that the flag 11 is no longer pushed into the finisher 119 by the uppermost surface of the sheets on the stack trays 18a and 18b. Can be detected.
[0046]
Not only the flag type sheet sensor 3 but also a light emitting unit for irradiating a sheet side stacked on the stack trays 18a and 18b with a light beam such as infrared rays, or one side to the other side of the stack trays 18a and 18b. The stack tray 18a has a light emitting unit that irradiates the light (for example, from the front side to the back side in FIG. 4) and a light receiving unit that receives the light, and the light is received or blocked and cannot be received. , 18b, the position of the upper surface of the sheet can be detected.
[0047]
The position detection signal detected by these detection means is input to the control unit 860 provided in the finisher body. The control unit 860 may be provided on the apparatus main body 101 side.
[0048]
In the present embodiment, the sheets stacked on the stack trays 18a and 18b are placed in the slats 25 in order to keep the distance between the position of the uppermost surface of the sheets stacked on the stack trays 18a and 18b and the discharge port 36 constant. In order to prevent leaning, the stack trays 18a and 18b are once moved downward and then moved up to a position where the sheet sensor 3 is turned on.
[0049]
In FIG. 4, reference numeral 5 denotes an upper surface detection sensor which is an upper surface detection means for detecting the upper surface of the sheets stacked on the lower stack tray 18b. The upper surface detection sensor 5 is the lower stack tray shown in FIG. It is arranged above the HP of 18b.
[0050]
By providing the upper surface detection sensor 5 at such a position, when stacking sheets on the upper stack tray 18a, the upper surface of the lower stack tray 18b above the HP is not the HP, as described above. The detection sensor 5 stands by at a position where the upper surface of the sheets stacked on the lower stack tray 18b is detected.
[0051]
Then, when the sheets are stacked again on the lower stack tray 18b by waiting on the upper side of the HP without lowering the lower stack tray 18b to the HP as described above, the lower stack tray 18b is placed on the sheet as described above. The moving time when moving to the loading position, that is, the tray switching time can be shortened.
[0052]
In FIG. 4, reference numeral 1 denotes a first lower limit sensor that detects a lower limit position of the stack trays 18 a and 18 b that gradually descends as the number of stacked sheets increases, and an upper surface detection sensor 5 is below the first lower limit sensor 1. It is arranged in. Reference numeral 29 denotes a second lower limit sensor that detects the lower limit position of the lower stack tray 18b.
[0053]
By providing the upper surface detection sensor 5 below the first lower limit sensor 1 that restricts the lowering of the stack trays 18a and 18b as described above, when the sheets are stacked on the upper stack tray 18a, the upper surface detection sensor 5 causes the stacked sheets to be stacked. It is possible to prevent the upper stack tray 18a from colliding with a sheet on the lower stack tray 18b that is waiting at a position where the upper surface is detected (hereinafter referred to as an upper standby position).
[0054]
(Sheet discharge processing)
Next, a sheet discharge process of the sheet processing apparatus 119 configured as described above will be described.
[0055]
For example, a case where sheets are stacked on the lower stack tray 18b after the sheets are discharged to the upper stack tray 18a will be described. The control unit 860 first rotates the stacker motors 209a and 209b in reverse to stack sheets on the upper stack tray 18a, and moves the lower stack tray 18b to the upper standby position, that is, the sheet surface detection sensor 5 as shown in FIG. The upper stack tray 18 a is moved to a sheet stacking position below the discharge port 36 while being lowered to a position where the stacking surface is detected.
[0056]
Next, after the sheets are discharged and stacked on the upper stack tray 18a moved to the sheet stacking position in this way and the stacking of a predetermined number of sheets is completed, or when the upper stack tray 18a is full, the stacker motor 209a. Is rotated forward to move the upper stack tray 18 a to the retreat position above the discharge port 36.
[0057]
When the tray is switched in this way, first, in order to prevent the backflow of the sheets stacked on the upper stack tray 18a, the shutter member (not shown) is raised to close the discharge port 36, and thereafter The stack tray 18a is raised.
[0058]
Next, as shown in FIG. 5, the lower stack tray 18b is raised and moved to the sheet stacking position until the sheet sensor 3 detects the upper surface of the lower stack tray 18b or the upper surface of the sheets stacked on the lower stack tray 18b. Then, the shutter member (not shown) is lowered to open the discharge port 36, and then the sheets are stacked on the lower stack tray 18b.
[0059]
Note that when stacking sheets on the lower stack tray 18b, the sheets in the lower stack tray 18b do not reach above the discharge port 36, so the upper stack tray 18a that has already been moved to the retreat position above the discharge port 36. Is located above the uppermost surface of the sheets stacked on the lower stack tray 18b.
[0060]
By the way, when sheets are stacked on the lower stack tray 18b in this way and then stacked again on the upper stack tray 18a, the lower stack tray 18b is first positioned at the position where the upper surface of the stacked sheets is detected by the paper surface detection sensor 5. After being lowered to a point, it stops and waits.
[0061]
In the present embodiment, the lower stack tray 18b is temporarily detected by the paper surface detection sensor 5 and then moved to a lower position where it cannot be detected, and then is raised and detected by the paper surface detection sensor 5. To move to a certain position.
[0062]
Next, as shown in FIG. 6, after the upper stack tray 18a is moved below the discharge port 36, the sheets S are discharged and stacked on the upper stack tray 18a. When the tray is switched in this way, first, in order to prevent the backflow of the sheets S stacked on the upper stack tray 18a, the shutter member (not shown) is raised to close the discharge port 36, and thereafter The upper stack tray 18a is lowered. Thereafter, the shutter member (not shown) is lowered to open the discharge port 36.
[0063]
Thereafter, when the sheets S are sequentially discharged to the upper stack tray 18a, the upper stack tray 18a is gradually lowered, and the upper stack tray 18a (the lower end) is detected by the lower limit sensor 1 in due course.
[0064]
Here, when detected by the lower limit sensor 1, the upper stack tray 18a moves to the upper standby position and the lower stack tray 18b rises from the position shown in FIG. 7 to the sheet stacking position.
[0065]
Here, when the sheets are stacked on the upper stack tray 18a, the lower stack tray 18b waits at the upper standby position as shown in FIG. 7, so that the upper surface of the stacked sheets reaches the sheet stacking position in a short time. You can move to a position. Thereafter, the sheets are stacked on the lower stack tray 18b.
[0066]
FIG. 8 is a diagram illustrating a state in which the upper stack tray 18a and the lower stack tray 18b are fully loaded by repeating the tray switching operation. Thus, when the stack trays 18a and 18b are fully loaded and the sheet S is removed from the upper stack tray 18a, the control unit 860 causes the sheet to be detected by the signal from the sheet presence / absence detection sensor 7 provided on the upper stack tray 18a. The upper stack tray 18a is raised to the loading position.
[0067]
When the sheet S is removed from the lower stack tray 18b, the control unit 860 raises the lower stack tray 18b to the upper standby position by a signal from the sheet presence / absence detection sensor 9 provided on the lower stack tray 18b. Thereby, the discharge of sheets to the stack trays 18a and 18b is continued.
[0068]
In the present embodiment, as shown in FIG. 4, the distance X2 between the upper surface detection sensor 5 and the second lower limit sensor 29 is the same as the distance X1 between the first lower limit sensor 1 and the sheet sensor 3 or more than the distance X1. It is set long. As a result, the lower stack tray 18b descends as the number of stacked sheets S increases and is detected by the first lower limit sensor 1, and thereafter the lower stack tray until it is lowered to the position detected by the second lower limit sensor 29. The upper surface of the sheet S stacked on 18 b can be detected by the upper surface detection sensor 5. Thereby, the sheet upper surface detection of the lower stack tray 18b by the second lower limit sensor 29 can be reliably performed.
[0069]
As described above, when the sheets S are stacked on the upper stack tray 18a, the lower stack tray 18b is placed at a position higher than the lower limit position of the HP, that is, the lower stack tray 18b unless the lower stack tray 18b is full of sheets. By making it wait, the switching time of the stack trays 18a and 18b can be shortened, and productivity can be improved.
[0070]
Further, by providing the upper surface detection sensor 5 below the first lower limit sensor 1 and above the HP, the descending upper stack tray 18a collides with a sheet on the lower lower stack tray 18b. Can be prevented.
[0071]
(Details of upper surface detection operation)
9 to 14 show a state in which the upper surface of the sheet stacked on the upper stack tray 18a is detected by the sheet sensor 3. FIG.
[0072]
(A) Operation when loading sheets
FIG. 9 is a diagram showing a state in which the upper surface is detected at any time after sheets are stacked on the upper stack tray 18a. (D0) represents a detection position where the upper surface of the upper stack tray 18a is detected by the sheet sensor 3 when there is no sheet. In FIG. 9A, sheets are stacked on the upper stack tray 18a, and the upper stack tray 18a is below (D0).
[0073]
After the sheets are stacked at the position shown in FIG. 9A, the upper stack tray 18a starts to descend. 9B, the flag 11 of the sheet sensor 3 is rotated and the detection unit 10 is turned off. At this time, the upper surface of the loaded paper is at the position (D0). From there, the upper stack tray 18a is further lowered by L2, and during that time, when the detection unit 10 is always OFF, the control unit 860 determines that the detection unit 10 is OFF, and at the position shown in FIG. The lowering operation of the tray 18a is stopped.
[0074]
Thereafter, the sheet is moved up to a position where the detection unit 10 of the sheet sensor 3 is turned on, and the upper surface detection operation is finished. In this embodiment, L2 = 0, that is, the control unit 860 determines OFF immediately after the detection unit 10 is turned off.
[0075]
(B) Operation when switching trays
10 and 11 are diagrams showing how the upper stack tray 18a is detected when the upper surface is lowered from the retracted position.
[0076]
FIG. 10A shows the way of lowering from the retracted position, and the upper stack tray 18a is above the detection position (D0) of the sheet sensor 3. FIG. By lowering the upper stack tray 18a, the flag 11 of the sheet sensor 3 is rotated as shown in FIG. 10B, and the detection unit 10 is turned on.
[0077]
Then, the upper stack tray 18a is lowered to the position shown in FIG. 11A, the flag 11 of the sheet sensor 3 is rotated, and the detection unit 10 is turned off. At this time, the upper surface of the loaded paper is at the position (D0).
[0078]
Thereafter, the control unit 860 is lowered by L1, and when the detection unit 10 is kept OFF during that time, the control unit 860 determines OFF of the detection unit 10 at that position (D1) and stops the lowering operation of the upper stack tray 18a.
[0079]
Then, it moves up to a position where the detection unit 10 of the sheet sensor 3 is turned on, and the upper surface detection operation is finished. The value of L1 is L1> L2, and is set to be equal to or greater than the length G of the gap described later.
[0080]
(C) Tray switching operation with curled paper loaded
12 to 14 are diagrams showing how the uppermost surface of the sheet is detected when the upper stack tray 18a is lowered from the retracted position when the stacked sheets are curled.
[0081]
As described above, when the curled sheets are stacked on the upper stack tray 18a and the upper stack tray 18a descends from the retracted position, the curled sheets lean against the slats 25, as shown in FIG. A gap G is formed between the upper stack tray 18a and the lowermost surface of the sheet.
[0082]
FIG. 12A shows the way of lowering from the retracted position, and the upper stack tray 18a is above the detection position (D0) of the sheet sensor 3. FIG. By lowering the upper stack tray 18a, the flag 11 of the sheet sensor 3 is rotated as shown in FIG. 12B, and the detection unit 10 is turned on.
[0083]
Then, the upper stack tray 18a is lowered to the position shown in FIG. 13A, the flag 11 of the sheet sensor 3 is rotated, and the detection unit 10 is turned off. At this time, the upper surface of the upper stack tray 18a is at the position (D0).
[0084]
Thereafter, as shown in FIG. In the meantime, the detection unit 10 cannot be turned off all the time, and the flag 11 of the sheet sensor 3 rotates counterclockwise in the middle of the detection unit 10 and the detection unit 10 is turned on.
[0085]
Therefore, at the position (D1) lowered by L1, the control unit 860 cannot determine that the detection unit 10 is OFF, and the upper stack tray 18a continues the lowering operation. And it descends to the position shown in FIG. At this time, the flag 11 of the sheet sensor 3 rotates and the detection unit 10 is turned OFF, and the upper surface of the stacked sheets is at the position (D0).
[0086]
Thereafter, as shown in FIG. Meanwhile, since the detection unit 10 is always OFF, the control unit 860 determines that the detection unit 10 is OFF at the position (D1), and stops the lowering operation of the upper stack tray 18a. Then, it moves up to a position where the detection unit 10 of the sheet sensor 3 is turned on, and the upper surface detection operation is finished.
[0087]
Since such an operation is performed, the sheet does not block the discharge port, and the upper surface of the stacked paper can be reliably detected.
[0088]
In the present embodiment, the operation in the state where the sheets are stacked on the stack trays 18a and 18b has been described, but it is needless to say that the same operation may be performed even when there are no sheets.
[0089]
In FIG. 4, when the upper stack tray 18a is lowered from the retracted position, when it is determined that the sheet presence / absence detection sensor 7 is ON and sheets are stacked, the above-described (B). An operation may be performed. In other words, if the detection unit 10 remains OFF during the time period when L1 is lowered, the detection unit 10 is determined to be OFF. In this case as well, L1> G is set as described above. When the sheet presence / absence detection sensor 7 is turned off and it is determined that there is no sheet, as shown in (A) above, if the detection unit 10 is kept OFF during the lowering by L2 (<L1), the detection unit You may make it confirm 10 OFF. Thereby, the operation time when the sheets are not stacked can be further shortened.
[0090]
Further, when discharging and stacking sheets on the lower stack tray 18b, the same operation as that of the sheet sensor 3 can be performed.
[0091]
The lower stack tray 18b and the sheet presence / absence detection sensor 9 can be operated similarly. For example, the detection unit 10 may be turned off after L1 is lowered, or L1 and L2 are used separately in combination with the sheet presence / absence detection sensor 9 that detects whether there is a sheet on the lower stack tray 18b. Also good.
[0092]
In the above description, the sheet processing apparatus that performs the binding process as the sheet process and the image forming apparatus including the sheet processing apparatus have been described as examples. However, the present invention is not limited thereto, and the punching process is performed as the sheet process. It goes without saying that it can also be applied to those that do.
[0093]
Further, although the sheet processing apparatus having two trays has been described so far, it goes without saying that the present invention can be applied to one having one or three or more trays.
[0094]
【The invention's effect】
As described above, the claims 1 and 3 According to the described invention, the loading means The Lowering from the top of the discharge means If you want to let Discharge means From Discharged sheet Loading from the time when the detection unit detects that the flag has been displaced from the second position to the first position, rather than lowering the loading means when sequentially loading the loading means located below the discharging means. The descending amount of the means is large Therefore, even when curled sheets are stacked, it is possible to accurately detect the upper surface of the sheets on the stacking means without blocking the sheet discharge port.
[0095]
Claims 2 and 3 Similarly, in the described invention, the loading means The Lowering from the top of the discharge means Let When When the detection result of the sheet detection means indicates that there is a sheet, the stacking from when the detection unit detects that the flag has been displaced from the second position to the first position is greater than when the detection result indicates that there is no sheet. The descending amount of the means is large Therefore, even when curled sheets are stacked, it is possible to accurately detect the upper surface of the sheets on the stacking means without blocking the sheet discharge port.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet processing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an internal configuration of a finisher 119. FIG.
FIG. 3A is a diagram showing that the upper stack tray 18a is disposed at the sheet stacking position and the lower stack tray 18b is disposed at the initial position. FIG. 6B is a diagram illustrating that the upper stack tray 18a is disposed at the retracted position and the lower stack tray 18b is disposed at the sheet stacking position.
FIG. 4 is a diagram illustrating an internal configuration of the finisher 119.
FIG. 5 is a diagram illustrating that the stack tray 18b is lifted and moved to a sheet stacking position.
6 is a diagram illustrating an internal configuration of the finisher 119. FIG.
FIG. 7 is a diagram showing that the upper stack tray 18a is detected by the lower limit sensor 1 and is full.
FIG. 8 is a diagram illustrating an internal configuration of the finisher 119;
FIG. 9 is a diagram illustrating a state in which the upper surface is detected at any time after a sheet is stacked on the upper stack tray 18a.
FIG. 10 is a diagram illustrating a state in which an upper surface is detected when the upper stack tray 18a is lowered from the retracted position.
FIG. 11 is a diagram illustrating a state in which an upper surface is detected when the upper stack tray 18a is lowered from the retracted position.
12 is a diagram illustrating a state in which the uppermost surface of a sheet is detected when the upper stack tray 18a is lowered from the retracted position when the stacked sheets are curled. FIG.
FIG. 13 is a diagram illustrating a state where the uppermost surface of a sheet is detected when the upper stack tray 18a is lowered from the retracted position when the stacked sheets are curled.
FIG. 14 is a diagram illustrating a state in which the top surface of a sheet is detected when the upper stack tray 18a is lowered from the retracted position when the stacked sheets are curled.
FIG. 15 is a diagram illustrating a conventional example.
FIG. 16 is a diagram illustrating a conventional example.
[Explanation of symbols]
3 Sheet sensor
7 Sheet presence / absence detection sensor
9 Sheet presence / absence detection sensor
10 detector
11 flags
18a Upper stack tray
18b Lower stack tray
209a Stacker motor
209b Stacker motor
560 Paper discharge roller pair
860 control unit

Claims (3)

Discharging means for discharging the sheet;
Stacking means for sequentially stacking sheets discharged by the discharging means;
Drive means for raising and lowering the loading means;
A flag provided at a predetermined height for detecting the stacking means and a sheet on the stacking means, wherein the flag is located at a first position when not contacting the stacking means and the sheet; A flag positioned in a second position when in contact with the sheet;
A detection unit for detecting the position of the flag;
In the case where the stacking unit is lowered from above the discharging unit, the stacking unit is lowered when the sheets discharged from the discharging unit are sequentially stacked by the stacking unit located below the discharging unit. than to control the so that said driving means Do large amount descending of the loading means from when the flag is detected by said detection unit that the second position is displaced to the first position Control means to
A sheet processing apparatus comprising: Discharging means for discharging the sheet;
Stacking means for sequentially stacking sheets discharged by the discharging means;
Drive means for raising and lowering the loading means;
Sheet detecting means for detecting the presence or absence of sheets on the stacking means;
A flag provided at a predetermined height for detecting the stacking means and a sheet on the stacking means, wherein the flag is located at a first position when not contacting the stacking means and the sheet; A flag positioned in a second position when in contact with the sheet;
A detection unit for detecting the position of the flag;
In the case where Ru is lowered downwardly said stacking means from above said discharge means, towards the case where the detection result of said sheet detecting means indicates the presence sheet, than when indicating no sheet also, the flag is the second and control means for controlling so that said driving means Do large amount descending of the loading means from the time detected by the detecting unit that the displaced to the first position from the position,
A sheet processing apparatus comprising: Image forming means for forming an image on a sheet;
An image forming apparatus, comprising a sheet processing apparatus according to claim 1 or 2.

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