PAPER SHEET PROCESSING APPARATUS

A paper sheet processing apparatus includes a processing tray, a feed member, a drive unit, a detection unit, and a control unit. The processing tray receives and stacks a plurality of paper sheets. The feed member faces the processing tray and includes a paddle that is elastically deformed by being pressed against the paper sheets during rotation. The drive unit rotates the feed member. The detection unit detects a leading end of the paper sheet being fed toward the alignment surface by the paddle. The control unit controls the drive unit based on a detection result during a period from if the detection unit detects the leading end of the paper sheet to if the paddle separates from the paper sheet and controls the rotation of the feed member so that the leading end of the paper sheet scraped by the paddle is aligned with the alignment surface.

FIELD

Embodiments described herein relate generally to, for example, a paper sheet processing apparatus that stacks and aligns a plurality of paper sheets, an image forming apparatus and methods related thereto.

BACKGROUND

As a multifunction peripheral having copy function, print function, scan function, and the like, for example, one equipped with a finisher that stacks and binds a predetermined number of sheets after image formation is known. A finisher includes a standby tray, a processing tray, and a stapler.

While the predetermined number of sheets stacked on the processing tray are aligned and stapled, the standby tray causes the next two or three sheets to be stapled to wait above the processing tray. There is a feed member with a paddle between the standby tray and the processing tray. The feed member rotates while the paddle contacts the upper surface of the paper falling from the standby tray to the processing tray, scrapes the paper toward the alignment surface of the stopper at one end of the processing tray, and aligns the edges of the paper against the alignment surface.

If the paper stacked in the standby tray is dropped into the processing tray, the stacking posture of the paper tends to be disturbed. In addition, the stacking posture of the paper on the processing tray tends to vary depending on the paper size, weight, thickness, material, and presence or absence of curls and wrinkles. Therefore, even if the feed member is rotated and an attempt is made to align the edges of the paper against the alignment surface, the edges of the paper may not reach the alignment surface or bounce off the alignment surface and the edges of the paper tend to be unaligned.

DETAILED DESCRIPTION

In general, according to one embodiment, a paper sheet processing apparatus includes a processing tray, a feed member, a drive unit, a detection unit, and a control unit. The processing tray receives and stacks a plurality of paper sheets. The feed member is rotatably arranged above the processing tray to face the processing tray and includes a paddle that is elastically deformed by being pressed against the paper sheets during rotation to scrape the paper sheets stacked on the processing tray toward an alignment surface by the paddle. The drive unit rotates the feed member. The detection unit is arranged between the feed member and the alignment surface and detects a leading end of the paper sheet being fed toward the alignment surface by the paddle. The control unit controls the drive unit based on a detection result of the detection unit during the period from if the detection unit detects the leading end of the paper sheet to if the paddle separates from the paper sheet and controls the rotation of the feed member so that the leading end of the paper sheet scraped by the paddle is aligned with the alignment surface.

A multifunction peripheral10equipped with a finisher1according to one embodiment will be described below with reference to the drawings. In the drawings used for the following description, the scale of each part may be changed as appropriate. Also, in the drawings used in the following description, the configuration may be omitted in some cases for the sake of easy understanding of the description.

As shown inFIG.1, the multifunction peripheral10includes a housing12forming the outer shell of the device and includes a document table121made of a transparent glass plate on the upper surface of a housing12. An automatic document feeder14(hereinafter, simply referred to as ADF14) is placed on the document table121. The ADF14can open and close the document table121. The ADF14automatically feeds a document D to a reading position on the document table121.

For example, if the operator sets the document D on a paper feed tray141of the ADF14and sets the presence or absence of stapling, the method of stapling, the number of copies, the paper size, and the like, and then presses the copy start switch, the multifunction peripheral10automatically feeds the documents D on the paper feed tray141one by one to the document reading position on the document table121. After reading the document D, the multifunction peripheral10automatically discharges the document D at an appropriate timing.

Various data input by the operator can be performed via the control panel of the multifunction peripheral10or via an external device such as a personal computer connected to the multifunction peripheral10.

The multifunction peripheral10includes a scanner unit16, a printer unit18, cassettes21,22, and23for paper P, and the like inside the housing12. The multifunction peripheral10also includes a large-capacity feeder24containing a large amount of paper of the same size and a manual feed tray25on the right wall of the housing12in the drawing which will be described later. Further, the multifunction peripheral10has the finisher1connected to the left wall of the housing12in the drawing. The finisher1is an example of the paper sheet processing apparatus described in the claims of the present application.

The scanner unit16illuminates and scans the document D fed to the document reading position on the document table121by the ADF14, reads and photoelectrically converts the reflected light, and obtains image information of the document

The printer unit18operates a laser device181based on the image information read by the scanner unit16to form an electrostatic latent image on the circumferential surface of a photosensitive drum182based on the image information. The printer unit18supplies toner to the electrostatic latent image on the photosensitive drum182via a developing device183to visualize the latent image, and transfers the toner image to the paper P by a transfer charger184. At this time, the multifunction peripheral10feeds the paper P from the cassettes21,22, and23, a large-capacity feeder24, or the manual feed tray25.

Further, the multifunction peripheral10supplies the paper P onto which the toner image was transferred to a fixing device185, heats, melts, and then fixes the toner image on the paper P, and discharges the paper to the finisher1through a discharge port20. After passing through the fixing device185, the multifunction peripheral10conveys the paper P, which requires double-sided copying, to a reversing conveying path26and reverses the front and back sides of the paper P, and then sends to the fixing region between the photosensitive drum182and the fixing device185again.

The paper P discharged through the discharge port20is an example of paper sheets described in the claims of the present application. Hereinafter, for convenience of explanation, the paper P discharged to the finisher1through the discharge port20of the multifunction peripheral10will be referred to as a paper sheet M.

The finisher1stacks and aligns the paper on which images are formed, that is, the paper sheets M discharged through the discharge port20of the multifunction peripheral10, and staples each unit of paper sheets M with the stapler8, with a predetermined number of stacked paper sheets M as one unit. The stapling process refers to a process of aligning and binding one-side ends of a plurality of stacked paper sheets M.

The finisher1includes an entrance roller2and an entrance sensor3at a position facing the discharge port20of the multifunction peripheral10. The entrance sensor3detects the passage of the leading end and the trailing end of the paper sheet M fed into the finisher1via the entrance roller2in the feeding direction (direction of arrow T in the drawing).

The finisher1includes a standby tray4, a processing tray6, and a stapler8. The standby tray4stacks and waits for two or three paper sheets M fed in the direction of the arrow T through the entrance roller2. The processing tray6receives the paper sheets M dropped from the standby tray4and aligns the trailing ends thereof for stapling. The stapler8staples the trailing ends of the paper sheets M stacked and aligned on the processing tray6. The standby tray4and the processing tray6are inclined downward toward the trailing ends of the paper sheets M in the feeding direction.

Since the stapling process by the stapler8requires a certain amount of processing time, when one unit of the paper sheets M on the processing tray6is being stapled, several paper sheets M fed as the next unit are required to stand by at a place different from the processing tray6. In the present embodiment, if the preceding one unit of paper sheets M is being stapled, two of the next one unit of paper sheets M are made to stand by on the standby tray4, and the time for stapling the preceding one unit of paper sheets M is ensured.

That is, the first paper sheet M and the second paper sheet M fed in the direction of the arrow T are stacked on the standby tray4and after the preceding one unit of stapling is completed, two paper sheets M made to stand by are dropped onto the processing tray6, and the third and subsequent paper sheets M are directly stacked on the processing tray6via the standby tray4.

As shown inFIG.2, the standby tray4includes two opening and closing trays401and402that open and close in a direction crossing the feeding direction T of the paper sheets M (the direction of the arrow W in the drawing) (hereinafter, this direction is referred to as the width direction W). The opening and closing trays401and402are connected to a motor, for example, via a rack and pinion mechanism (not shown), and open and close between a support position for supporting the paper sheet M fed in the direction of the arrow I near the trailing end corners in the feeding direction, and a release position where the support is released.

If the opening and closing trays401and402are opened to the release position, the paper sheets M stacked on the standby tray4drop onto the processing tray6due to their own weight. At this time, since the width of the opening formed between the two opening and closing trays401and402widens toward the upstream side in the feeding direction, if the opening and closing trays401and402are opened, the trailing ends of the stacked paper sheets M in the feeding direction first fall toward the processing tray6.

On the upstream side of the standby tray4in the feeding direction, there is a paper feed roller31that clamps the paper sheets M fed in the direction of the arrow T and feeds the clamped paper sheets M to the standby tray4, as shown inFIG.1. The paper feed roller31includes a plurality of upper rollers311and lower rollers312facing each other. The paper feed roller31starts the rotation if the entrance sensor3detects the leading end passage in the feeding direction of the paper sheet M as a trigger and stops the rotation if the entrance sensor3detects the trailing end passage in the feeding direction of the paper sheet M as a trigger.

As shown inFIG.1, the finisher1includes a standby tray roller32(not shown inFIG.2) downstream of the standby tray4in the feeding direction. The standby tray roller32is arranged to face the mounting surface of the standby tray4so as to be separable and rotatable in both forward and reverse directions. That is, the standby tray roller32rotates in the reverse direction to slightly convey and align the paper sheet M fed to the standby tray4in the direction opposite to the feeding direction T, and after stacking the paper sheets M which do not require stapling on the standby tray4, the standby tray roller32rotates forward to discharge the paper sheets toward the discharge trays36and38. The discharge trays36and38can move up and down.

When stacking the paper sheets M on the standby tray4, the finisher1retracts the standby tray roller32upward and lowers the standby tray roller32toward the standby tray4after stacking the paper sheets M. The finisher1rotates the standby tray roller32in the reverse direction while keeping the standby tray roller32in contact with the paper sheets M stacked on the standby tray4, and then aligns the paper sheets by abutting the trailing end of the paper sheets M in the feeding direction against a stopper (not shown). After that, the standby tray roller32is retracted upward again in order to receive the paper sheet M to be fed next onto the standby tray4.

The processing tray6has a flat mounting surface61on its bottom for placing and stacking the paper sheets M dropped from the standby tray4. The mounting surface61is inclined downward toward the upstream side in the feeding direction of the paper sheets M. Under the processing tray6, there is a conveying mechanism34(seeFIG.1) for conveying the paper sheets M stacked and placed on the processing tray6toward the discharge trays36and38, which will be described later. The processing tray6has an opening62at its bottom for exposing a portion of the conveying mechanism34above the mounting surface61.

Between the standby tray4and the processing tray6, there are two feed members40as partially enlarged inFIG.3. In the present embodiment, two feed members40are provided spaced apart from each other in the rotation axis direction, but three or more feed members40may be provided. The structure shown inFIG.3is incorporated in the space indicated by S inFIG.2.

The feed member40acts on the trailing end of the paper sheets M received in the standby tray4in the feeding direction. The feed member40guides the trailing end of the paper sheet M toward the processing tray6. Further, the feed member40scrapes the vicinity of the trailing end of the paper sheet M dropped onto the processing tray6in the direction opposite to the feeding direction.

As shown inFIG.4, each feed member40includes a receiving portion42for supporting from below the trailing end of the paper sheet M fed to the standby tray4in the feeding direction, a hitting portion44for hitting down the trailing end supported by the receiving portion42, a paddle46for scraping the vicinity of the trailing end of the paper sheet M dropped on the processing tray6toward the stopper50, an auxiliary paddle47, and a rotating body48. The rotating body48fixes the trailing ends of the receiving portion42, the hitting portion44, the paddle46, and the auxiliary paddle47, spaced apart in the circumferential direction.

The protruding length of the auxiliary paddle47from the rotating body48is slightly shorter than the protruding length of the paddle46. The protruding length of the paddle46and the auxiliary paddle47is such that the leading end of each paddle at least contacts the mounting surface61of the processing tray6during the rotation of the feed member40. The feed member40rotates in the direction of arrow R (counterclockwise direction) in the drawing.

The basic operation of the finisher1described above will be described below with reference toFIGS.5to9. In the following description, the direction in which the paper sheets M are fed from the multifunction peripheral10to the standby tray4of the finisher1is referred to as the feeding direction, and the direction of scraping and feeding the paper sheets M that dropped from the standby tray4to the processing tray6toward the stopper50is referred to as the abutting direction. Further, in the following description, the trailing end of the paper sheet M in the feeding direction may be referred to as the leading end m in the abutting direction.

First, if the paper sheet M is fed from the multifunction peripheral10to the finisher1, the feed member40is on standby while being rotated to the home position shown inFIG.5. In this state, if the paper sheet M is fed to the standby tray4, the trailing end of the paper sheet M in the feeding direction rides on the receiving portion42of the feed member40. As described above, the standby tray4is inclined downward toward the upstream side in the feeding direction. Therefore, the paper sheet M fed to the standby tray4is biased toward the trailing end side by its own weight, and the center of the trailing end of the paper sheet M hangs downward from between the opening and closing trays401and402. In other words, the receiving portion42of the feed member40supports the vicinity of the center of the trailing end of the hanging paper sheet M from below.

In this state, if the second paper sheet M is fed to the standby tray4, the second paper sheet M overlaps the first paper sheet M, and the trailing end of the second paper sheet M rides on the receiving portion42of the feed member40. After that, the finisher1opens the opening and closing trays401and402, rotates the feed member40as shown inFIG.6to release the support by the receiving portion42, to hit the trailing ends of the paper sheets M by the hitting portion44, and to make the paper sheets M in a state of being two-ply drop toward the processing tray6. Here, a case will be described in which one paper sheet M is made to stand by on the standby tray4and drop onto the processing tray6, but the number of paper sheets M stacked on the standby tray4before being hit down can be changed to any number.

As described above, since the width of the opening between the opening and closing trays401and402widens toward the upstream in the feeding direction, the trailing end side of the paper sheet M on the standby tray4is released from the support first, as shown inFIG.6, the trailing end is first directed to the processing tray6. At the same time, since the center of the trailing end of the paper sheet M is hit downward toward the processing tray6by the hitting portion44, the trailing end of the paper sheet M is forcibly directed toward the processing tray6first.

After the paper sheet M drops onto the processing tray6, if the feed member40is further rotated from the state shown inFIG.6, the leading end of the paddle46of the feed member40comes into contact with the upper surface of the paper sheet M as shown inFIG.7. If the feed member40is further rotated from this state, the paddle46elastically deforms and moves while curving, after the elastic deformation of the paddle46reaches its peak, if the leading end of the paddle46in the protruding direction separates from the paper sheet M, the paper sheet M is flipped off toward the stopper50by the restoring force of the paddle46. That is, the paddle46operates to scrape the vicinity of the trailing end (that is, the leading end m in the hitting direction) of the paper sheet M toward the stopper50.

Also, at this time, the conveying mechanism34operates to convey the paper sheets M stacked on the processing tray6toward the stopper50in cooperation with the scraping operation of the paddle46. The length of the paddle46is such that it can at least be pressed against the processing tray6if the feed member40is rotated. Therefore, the paddle46is pressed against the upper surface of the paper sheet M on the processing tray6and is elastically deformed and curved.

After that, as shown inFIG.8, the feed member40is rotated to the same posture (home position) as if the paper sheet M was received, and the next paper sheet M is conveyed to the standby tray4. The trailing end of the paper sheet M in the feeding direction is supported by the receiving portion42of the feed member40. A predetermined number of paper sheets M are stacked on the processing tray6by repeating the above operation. If a plurality of paper sheets M are to wait in the standby tray4, the rotation of the feed member40only needs to be stopped until the waiting number of paper sheets M are conveyed to the standby tray4.

The leading end of the auxiliary paddle47comes into contact with the upper surface of the paper sheet M immediately before the feed member40rotates to the position shown in FIG.8. The auxiliary paddle47functions to prevent the paper sheet M from rebounding if the paper sheet M whose leading end m in the abutting direction abuts against the alignment surface51of the stopper50tries to return in the opposite direction. Further, the auxiliary paddle47functions to feed the paper sheet M whose leading end m did not reach the alignment surface51of the stopper50toward the alignment surface51.

As described above, if a predetermined number of paper sheets M are stacked on the processing tray6and their leading ends m in the abutting direction are aligned, the finisher1moves the stapler8movably installed along the leading ends m to the stapling position as shown inFIG.9, and binds a predetermined number of paper sheets M in one unit at an appropriate position. After that, the finisher1operates the conveying mechanism34to convey the bundle of paper sheets M bound at the leading ends m toward the discharge trays36and38.

Since the paper sheet M fed from the multifunction peripheral10to the finisher1just underwent image formation, the paper sheet M may be slightly curled due to the application of heat. The degree of curling of the paper sheet M varies depending on the thickness, basis weight, size, and the like of the paper P even if the amount of heat given by the fixing device185is the same. In addition, since the finisher1needs to drop the paper sheet M from the standby tray4to the processing tray6, the stacking posture of the paper sheets M on the processing tray6tends to vary. Therefore, it is difficult to neatly align the leading ends m of all the paper sheets M in the abutting direction with the alignment surface51by simply processing all the paper sheets M fed to the processing tray6of the finisher1in the same manner of rotating the feed member40at the same timing and at the same speed. By providing the above-described auxiliary paddle47, the leading ends m can be aligned with the alignment surface51to some extent, but it cannot be said to be sufficient.

On the other hand, the inventors of the present application have proposed that, in order to further improve the alignment of the leading ends m of the paper sheets M on the processing tray6of the finisher1, the rotation speed and the control timing of the feed member40are adjusted according to the state of the paper sheets M that dropped onto the processing tray6. A configuration for controlling the rotation of the feed member40and a control method thereof will be described below.

As shown inFIG.4, the finisher1includes a detection unit70that detects the leading end m of the paper sheet M being scraped toward the alignment surface51of the stopper50by the paddle46of the feed member40. The detection unit70is located above the mounting surface61of the processing tray6to face the mounting surface61with a space therebetween. The detection unit70is between the feed member40and the alignment surface51. In other words, the detection unit70detects the passage of the leading end m of the paper sheet M that passed through the feed member40and is directed toward the alignment surface51. The detection unit70includes a contactor72, a magnet74, and an angle sensor76.

The contactor72has a shape curved in the direction of the alignment surface51toward the mounting surface61from a position spaced above the mounting surface61of the processing tray6. The contactor72is rotatable with respect to the housing of the finisher1. The contactor72has a contact end73near the leading end of rotation, which contacts the upper surface of the paper sheet M during rotation. If the contact end73contacts the paper sheet M, the contactor72is lifted by the thickness of the paper sheet M and rotates slightly counterclockwise in the drawing.

FIG.10shows an example of a state in which there is no paper sheet M between the contact end73of the contactor72and the mounting surface61of the processing tray6, andFIG.11shows an example of a state in which the leading end m of the paper sheet M is inserted therebetween. Before the paper sheet M is sent to the processing tray6(the state shown inFIG.10), the contactor72presses the contact end73against the mounting surface61by its own weight. As shown inFIG.11, if the leading end m of the paper sheet M is sent between the mounting surface61and the contact end73, the contact end73is pushed up by the thickness of the paper sheet M, and the contactor72rotates slightly counterclockwise in the drawing.

The magnet74can rotate integrally with the contactor72. The magnet74is, for example, disc-shaped and is polarized in a plane including its central axis. The rotating base end portion of the contactor72can rotate coaxially with the central axis of the magnet74. That is, if the leading end m of the paper sheet M reaches the contact end73of the contactor72and the contactor72rotates in the direction in which the contact end73moves away from the mounting surface61, the magnet74also rotates by the same angle in the same direction.

The angle sensor76faces across the two magnetic poles of the magnet74and is fixed to the housing of the finisher1. The angle sensor76detects a change in the direction of the magnetic field that changes due to the rotation of the magnet74, and detects the rotation angle of the magnet74, that is, the rotation angle of the contactor72from the amount of change. By sufficiently increasing the resolution of the angle sensor76, slight rotation of the contactor72corresponding to the thickness of the paper sheet M can be detected.

For example, if the next paper sheet M is sent to the processing tray6in a state where several paper sheets M are stacked on the processing tray6, the contact end73of the contactor72is in contact with the upper surface of the uppermost paper sheet M of already stacked several paper sheets M. If a new paper sheet M is fed between the contact end73and the contact end73from this state, the contactor72rotates by the thickness of the paper sheet M. That is, the detection unit70can detect the leading end m of the newly fed paper sheet M regardless of the number of paper sheets M already stacked on the processing tray6. Since the contact end73of the contactor72moves in an arc shape, strictly speaking, the position in the abutting direction for detecting the leading end m shifts slightly depending on the number of paper sheets M stacked on the processing tray6.

As shown inFIG.12, the finisher1includes a control unit80that controls the rotation of the feed member40. The control unit80connects the detection unit70, a memory82, a timer84, and a drive unit86via a bus line81.

The detection unit70detects the leading end m of the paper sheet M that was fed into the processing tray6and is being scraped toward the alignment surface51by the paddle46. The memory82stores a control table in which the optimal deceleration and deceleration start timing of the feed member40with respect to the output value of the detection unit70are measured in advance for each thickness, basis weight, and size of the paper P. The optimal deceleration and deceleration start timing of the feed member40, which were measured in advance for each thickness, basis weight, and size of the paper P, are examples of optimal control values described in the claims of the present application and are the optimal values for aligning the paper sheet M with the alignment surface51.

The timer84measures the time from if the feed member40is rotated from the home position shown inFIG.5to if the detection unit70detects the leading end m of the paper sheet M. The drive unit86is a motor or the like that rotates the feed member40at a variable speed based on the detection result of the detection unit70.

As shown inFIG.13, the finisher1waits for the paper sheet M to be fed from the multifunction peripheral10in ACT1. In the standby state before the paper sheet M is fed to the standby tray4, the feed member40is rotated to the home position shown inFIG.5and stopped. If the paper sheet M is fed from the multifunction peripheral10to the finisher1(ACT1; YES), the control unit80controls the drive unit86to rotate the feed member40from the home position, and drops the paper sheet M in the standby tray4onto the processing tray6in ACT2. At this time, the finisher1opens the standby tray4to the release position as the feed member40rotates.

The control unit80rotates the feed member40in ACT2, and at the same time, starts measuring the time by the timer84in ACT3, and continues measuring the time until the detection unit70detects the leading end m of the paper sheet M in ACT4(ACT4; YES) (ACT5). After that, the control unit80acquires the optimal control value from the control table stored in the memory82based on the time measured in ACT5and the information of the paper P (thickness, basis weight, size, and the like) input in advance (ACT6), and controls the drive unit86according to the control value (ACT7). The time from if the feed member40is rotated until the detection unit70detects the leading end m of the paper sheet M includes the information about the position of the leading end m of the paper sheet M dropped onto the processing tray6along the abutting direction.

The control of ACT7includes control of the rotation speed of the feed member40and control of the timing of the control start. For example, if the leading end m of the paper sheet M that dropped onto the processing tray6is placed at a position farther from the alignment surface51than the designed value, the time measured by the timer84in ACT5becomes longer than the designed value. In this case, the control unit80controls the drive unit86so as to decrease the deceleration of the feed member40or delay the start timing of deceleration. Further, if the leading end m of the paper sheet M that dropped onto the processing tray6is positioned at a position closer to the alignment surface51than the designed value, the time measured by the timer84in ACT5becomes shorter than the designed value. In this case, the control unit80controls the drive unit86so as to increase the deceleration of the feed member40or advance the deceleration start timing. In any case, the control unit80controls the rotation of the feed member40so that the leading ends m of all the paper sheets M abut against the alignment surface51at approximately the same speed and aligned.

The control unit80repeats the processes of ACT1to ACT7until a predetermined number of paper sheets M of one unit are stacked on the processing tray6and the leading ends m are aligned, and the leading ends m of the predetermined number of paper sheets M of one unit are aligned (ACT8; YES), and the process ends. After that, the finisher1uses the stapler8to staple the leading ends m of the predetermined number of paper sheets M.

As described above, according to the present embodiment, even if the position of the leading end m of the paper sheet M dropped from the standby tray4to the processing tray6varies in the abutting direction, the leading ends m of all the paper sheets M can be neatly aligned with the alignment surface51. Therefore, according to the present embodiment, the stapled bundle of paper sheets M is neatly arranged, and the reliability of the finisher1can be improved.

Further, according to the present embodiment, the memory82stores a control table in which the optimal control values for the feed member40are measured in advance according to the thickness, basis weight, size, and the like of the paper P on which the image is to be formed by the multifunction peripheral10. Then, after the feed member40is rotated, the optimal control value based on the time until the detection unit70detects the leading end of the paper sheet M is read out from the control table, and the feed member40is controlled to rotate. Therefore, regardless of the type of paper P, the leading ends m of the paper sheets M can be neatly aligned before stapling. Further, according to the present embodiment, since the thickness of the paper sheet M can be detected via the detection unit70, rotation control based on an optimal control value matching the thickness detected by the detection unit70is also possible.

Further, as described above, the contact end73of the contactor72swings to draw an arc track. Depending on the number of the paper sheets M fed to the processing tray6, the detection unit70makes a difference in the position in the abutting direction for detecting the leading end m. For example, the position for detecting the leading end m of the seventh paper sheet M fed on top of the six stacked paper sheets M is the side closer to the alignment surface51from the position for detecting the leading end of the second paper sheet M. Therefore, in consideration of this difference, an optimal control value for the feed member40corresponding to the number of stacked sheets may be prepared in advance in the control table.