JP2003246537A - Sheet post-processing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the alignment consistency of a sheet upon post processing the sheet. <P>SOLUTION: This sheet post processing device 300 having a staple H and post processing a conveyed sheet S comprises a discharge upper roller 330a and a discharge lower roller 330b which are mutually separable, and has a discharge roller pair 330 for discharging a sheet, an intermediate loading part 300B formed when the upper roller 330a of the discharge roller pair 330 evacuates and loading the sheet temporarily, a slide guide abutting on widthwise sides of the sheet, movable in the width direction of the sheet, and aligning the sheet on the intermediate loading part 300B. At least a part of an outer circumferential surface of the discharge lower roller 330b of the discharge roller pairs 330 is provided with a kick out member whose downstream side in a sheet conveyance direction kicks out the rear end of the sheet, and formed in a tapered shape or a circular arc shape in which a radius of rotation decreases from the peak of a kick out member to the upstream side in the conveyance direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet post-processing apparatus and an image forming apparatus having the sheet post-processing apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a plurality of sheets on which an image has been formed (printed) are ejected after aligning their ends and performing post-processing such as stapling. Some are equipped with a post-processing device. In such a sheet post-processing apparatus, sheets printed on the image forming apparatus main body side can be sequentially supplied from the ejection port, aligned at their ends, post-processed, and ejected. Further, there is known a stacker capable of stacking sheets without post-processing.

[0003]

However, in such a conventional image forming apparatus, the intermediate stacking unit for aligning the sheets for the stapling operation is separated from the sheet path for ejecting the sheets not subjected to the stapling operation. In some cases, the size of the device is increased due to the provision.

When the intermediate stacking unit for aligning the sheets before the stapling operation is formed on the discharge roller pair 630a, 630b arranged on the downstream side, as shown in FIG. Lower roller 630b of a pair of discharge rollers having a comb tooth structure
Since the upper surface of the sheet is above the sheet path (h in the figure), when the sheet is conveyed while the pair of discharge rollers is stopped, the front end surface of the sheet is caught by the discharge roller and misalignment occurs. Sometimes. As a result, the sheets may be stapled with a large amount of deviation between the sheets. Further, there is a problem that the sheet is jammed in the device due to the sheet being caught.

It is an object of the present invention to improve sheet integrity when post-treating the sheet.

[0006]

A typical constitution of the present invention for achieving the above object is a sheet post-processing apparatus having post-processing means for performing post-processing on a conveyed sheet,
An intermediate roller configured to include an upper roller and a lower roller that can be separated from each other, and a discharge roller pair for discharging a sheet, and an upper roller of the discharge roller pair retracted to temporarily stack the sheets. At least a lower roller of the pair of discharge rollers includes a stacking unit and an aligning unit that is in contact with a side surface in the width direction of the sheet, is movable in the width direction of the sheet, and aligns the sheet on the intermediate stacking unit. A part of the outer peripheral surface of the sheet is provided with a kick-out portion that kicks out the rear end of the sheet on the downstream side in the sheet conveying direction, and has a taper shape or a circle whose radius of rotation decreases from the apex of the kicking portion toward the upstream side in the conveying direction. It is characterized by being configured in an arc shape.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. In each of the following embodiments,
An example of a sheet post-processing device mounted on a printer represented by a laser beam printer will be described.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Figure 1
FIG. 1 is a schematic cross-sectional view showing the overall configurations of a sheet post-processing device and an image forming apparatus (printer).

In FIG. 1, reference numeral 100 denotes a printer main body, which is independently connected to a computer or a network such as a LAN, and has a predetermined size based on image information and print signals sent from these computers and networks. It is a device that forms (prints) an image on a sheet by an image forming process and discharges the sheet.

On the other hand, a sheet post-processing apparatus as a post-processing section
A sheet 300 discharged from the printer main body 100 to the outside of the apparatus is placed on the intermediate stacking section 300B in a face-down state with the image side facing down, via a conveyance section in the sheet post-processing apparatus, and an alignment unit. The sheet is bundled for each predetermined job, stapled at one or a plurality of positions of the sheet and discharged and stacked on the sheet stacking unit 325 of the sheet post-processing apparatus, or simply face down of the sheet post-processing apparatus. This is a device for discharging and stacking on the sheet stacking unit 325.

Here, the sheet post-processing apparatus 300 and the printer main body 100 are electrically connected by a cable connector (not shown). Further, the sheet post-processing apparatus 300 has a casing section 300A for storing each section, and is configured to be attachable to and detachable from the apparatus main body 100A of the printer main body 100 described later.

Next, the configuration of each part of the printer main body 100 will be described along the conveyance path of the conveyed sheet S. In the printer main body 100, a plurality of sheets S are stacked in a feeding cassette 200, and various rollers sequentially separate and feed the uppermost one of these sheets. Then, according to a predetermined print signal supplied from the computer or the network, the feeding cassette 20
The sheet S fed from 0 has a toner image transferred onto the upper surface of the sheet by an image forming unit 101 that forms a toner image in the printer main body 100 by a so-called laser beam type image forming process, and then, on the downstream side. The fuser 120
The toner image is permanently fixed by applying heat and pressure.

As shown in FIG. 1, the sheet S on which the image is fixed is folded back in a substantially U-shaped sheet conveying path up to the discharge roller 130, so that the image surface is inverted and the image surface is on the lower side. In this state, the discharge roller 130 discharges the printer body 100 facedown to the outside. Here, the position of the flapper 150 of the printer body 100 of the sheet S is determined based on a control signal from a control unit (not shown), so that the face-down (FD) discharge provided on the upper portion of the printer body 100. It is selected whether the sheet is discharged to the section 125 or the sheet stacking section 325 of the sheet post-processing apparatus 300.

Next, the structure of the sheet post-processing device 300 and the movement of each part when the sheet S conveyed by the discharge roller 130 moves toward the sheet post-processing device 300 will be described with reference to FIGS. 2 and 3. . FIG. 2 shows a sheet post-processing device 30.
FIG. 3 is an enlarged view of 0, and FIG. 3 is an operation explanatory view of the slide guide at each position of the sheet S.

As shown in FIG. 2, the sheet post-processing device 300
Has a discharge upper roller 330a, a discharge lower roller 330b, a jogger motor M as a drive source, a paddle 322, and a reference wall 323 for abutting the rear end of the sheet.

The discharge roller pair 330 composed of the discharge upper roller 330a and the discharge lower roller 330b is arranged above the flapper 150 on the downstream side in the sheet conveying direction, and is rotationally driven by a drive motor (not shown). Also, the discharge upper roller 33
Reference numeral 0a is pivotally supported by an arm 331 which is rotatable around a paddle shaft 350.

The jogger motor M is a motor for driving each slide guide (301, 302) described later, and a stepping motor is used in this embodiment. The paddle 322 is made of a flexible material such as rubber,
A plurality of paddle shafts 350 are fixed in the direction perpendicular to the sheet conveying direction. The paddle shaft is driven and rotated in the clockwise direction to move the sheet S in the direction opposite to the sheet conveying direction, and bring the width direction side surface of the sheet S into contact with the reference wall 323 for alignment.

Further, as shown in FIG. 3, in the sheet post-processing apparatus 300 of the present embodiment, a slide guide R301 and a slide guide L302, which will be described in detail later, serve as alignment means for moving in the width direction of the sheet to perform alignment. Is provided.

In the sheet post-processing apparatus 300, when the stapling process is performed based on a command previously output from a computer or the like, before the sheet S to be stapled is ejected by the ejection roller 130, a solenoid (not shown) is used. The flapper 150 rotates counterclockwise in FIG. 2 through a link (not shown), and comes into contact with the stopper at the position of FIG.
Switched to 0. In this way, the sheet S is carried in through the entrance sensor 390 of the sheet post-processing device 300 by the roller pair provided downstream of the fixing device 120 of the printer body 100.

The sheet S carried into the sheet post-processing apparatus 300 rotates the flag of the entrance sensor 390 clockwise so that the flag allows the photo sensor to transmit light.
To detect the entry of. After that, it is conveyed upward by the pair of entrance rollers 363.

The sheet post-processing device 30 having such a configuration
0 indicates a sheet stacking unit 3 of the sheet post-processing device by stapling.
When the sheets are discharged and stacked on the sheet stacker 25, the sheets are discharged and stacked on the sheet stacking unit 325 of the sheet post-processing apparatus simply by face down. Hereinafter, cases will be described separately.

First, the operation of discharging and stacking face-down on the sheet stacking unit 325 of the sheet post-processing apparatus will be described. As shown in FIG. 4, in the sheet post-processing apparatus 300, the bottom surfaces of the slide guide R301 on the right side and the slide guide L302 on the left side with respect to the sheet carry-in direction are at positions where they do not contact the sheet S being carried in, that is, the sheet. The sheet S is retracted to a position outside by a predetermined amount from the width direction of the sheet S, and the sheet S is directly conveyed to the stacking unit of the sheet post-processing apparatus.

The sheet conveyed by the inlet roller pair 363 passes through the staple roller 320, and then passes through the frontage of the staple H as a post-processing means, and then the discharge roller pair 33.
The sheet stacking unit 325 of the sheet post-processing apparatus conveyed by 0
Loaded on.

The discharge roller pair 330 (330a, 330b) has a comb-teeth structure as shown in FIG. 10 in order to reliably discharge a thin sheet, and the sheets are arranged in a vertically staggered manner (staggered arrangement). Nip with a roller to convey the sheet. Further, the right and left ends of the discharge lower roller 330b are provided with a stiffening member having a diameter that increases as the distance from the sheet conveyance center increases. To take.

When the stacking capacity of the sheet stacking unit is small, that is, when the heights of the discharge roller pair 330 and the lower surface of the stacking unit are small, there is no problem in stacking even if the sheets are not stiffened. However, since this apparatus needs to increase the number of sheets to be stacked on the sheet stacking unit, it needs to be stiffened. As a result, the sheet stacking unit 325 of the sheet post-processing apparatus increases the stacking capacity, so that the sheet can be reliably stacked even if the sheet stacking unit 325 is arranged at a low position.

Further, in the discharge roller pair 330, a right kicking roller 330R and a left kicking roller 330L are provided at both ends of the lower discharging roller 330b so that the rear end of the sheet can be surely discharged to the sheet stacking section 325. The cross-sectional shapes of these kick rollers are configured as shown in FIG.

The sheet S is conveyed in the direction of the arrow, and the rollers (330R, 330L) rotate clockwise. At this time,
Since each of the kicking rollers 330R and 330L has the kicking-out portion 330K, the kicking-out portion 330K surely contacts the sheet S and kicks out. In addition, in order to impart rigidity to the thin sheet S, each of the kick rollers 330R and 330L has a roller diameter that increases toward the end of the sheet.
As a result, both ends of the sheet can be lifted upward and discharged, and the sheet is discharged substantially linearly until the rear end of the sheet passes through the discharge roller pair 330. The right kicking roller 330R and the left kicking roller 330L are bilaterally symmetrical.

Next, the operation of stapling and discharging and stacking on the sheet stacking unit 325 of the sheet post-processing apparatus will be described with reference to FIG. Incidentally, paddles not directly related to the present invention
The movement and drawing of 322 are omitted.

At this time, as shown in FIG. 3A, in the sheet post-processing apparatus 300, reference pins R303 provided on the wall surfaces of the right slide guide R301 and the left slide guide L302 in the sheet loading direction, The reference pin L304 is retracted to a position outside the width direction of the sheet S by a predetermined amount so that the reference pin L304 does not interfere with the conveyed sheet S. The distance between the width direction side surfaces of the bottom surface of the slide guide is smaller than the width of the sheet S (the supporting surface of the aligning means is inside the width of the sheet), and the sheet S waits for entry. This position is the standby position.

The first sheet is the entrance roller pair 363 and
After passing through the staple roller 320, after passing through the frontage of the staple H, it is conveyed by the discharge roller pair 330 and onto the guide surface of the intermediate stacking unit 300B constituted by the supporting surfaces of the slide guide R301 and the slide guide L302. Be transported. The sheet is conveyed with the central reference. The discharge roller pair 330 has a roller portion arranged in the direction perpendicular to the sheet conveying direction so as to be aligned with the sheet conveying center, so that the roller pair is evenly nipped on the left and right sides. At this time, all the rollers are in a rotating state.

As shown in FIG. 1, the guide surface of the intermediate stacking section 300B is inclined at a predetermined angle with respect to the horizontal direction, and has different inclination angles on the upstream side and the downstream side in the sheet carrying-in direction. Specifically, a bent portion 300C that is bent at an inclination angle α is formed between a predetermined section on the upstream side and a predetermined section on the downstream side. By having such a bent portion 300C on the guide surface of the intermediate stacking portion 300B,
Bending of the central portion of the sheet S that is not guided by the slide guides 301 and 302 is prevented.

As shown in FIG. 3A, the first sheet is nipped by the discharge roller pair 330 and conveyed onto the surface formed by the slide guide R301 and the slide guide L302.

Immediately after that, as shown in FIG. 3B, the arm 331 rotates counterclockwise, whereby the discharge upper roller 330a pivotally supported by the arm 331 retracts upward, and the discharge roller pair Simultaneously with the separation of 330, the drive connected to the discharge roller pair 330 is released to stop the rotation of the discharge upper roller 330a and the discharge lower roller 330b. At this time, the other rollers are still rotating. When the trailing edge of the sheet S has completely passed through the staple roller 320, the sheet returns to the direction opposite to the conveying direction by its own weight and moves toward the reference wall 323.

Next, only the left slide guide L302 is operated to start the widthwise alignment operation of the sheets stacked on the intermediate stacking section 300B. Specifically, when the slide guide L302 is driven by the motor M and moves in the direction of the slide guide R301, the reference pin L304 provided on the slide guide L302 abuts the side surface of the sheet S and the sheet S moves toward the slide guide R301. Push in. The side opposite to the sheet S is the slide guide R
By abutting the reference pin R303 provided on the 301 and the reference pin 305 provided on the main body of the post-processing apparatus, the alignment of the sheets in the width direction is performed.

As shown in FIG. 12, the surface of the roller portion of the lower discharge roller 330b of the discharge roller pair 330 has a structure protruding to the upper side of the sheet path (h in the figure). For this reason,
When the slide guide L302 performs the sheet aligning operation, the right kicking roller 330R of the discharge roller pair moves upward in the drawing while the sheet abuts. In the apparatus of the conventional example, the sheet to be aligned may come into contact with the side wall of the roller to be caught, and the kicking roller of the present invention, when the sheet is aligned, moves in the direction in which the sheet moves. As shown in FIGS. 5 and 6, the ribs a to d have a tapered shape T with respect to the sheet entrance direction indicated by the arrow.
Since the sheet S is provided, the seat S has a right kicking roller 330R.
In this way, it is possible to ensure the alignment without getting caught.

The sheet S is set so as to move to the position of the staple H set at the position where the sheet S is brought into contact with the reference pin R303 and aligned. After the aligning operation, the slide guide L302 moves in a direction in which it spreads wider than the width of the sheet S so that the sheet can be conveyed again at the standby position.

As shown in FIG. 3 (c), the second sheet S is conveyed with the center as reference, like the first sheet. 1
Since the second sheet moves to the slide guide R301 side (upper side in the drawing) in the alignment operation, when the second sheet moves on the discharge roller pair 330, the left kicking roller 330L
It is conveyed while making contact with. At this time, the discharge lower roller 33
0b is not rotating.

The kicking rollers 330R and 330L of the present invention are
As shown in the cross-sectional shape of FIG. 7, the sheet S is not ejected because the sheet is conveyed in the R direction and chamfered in the sheet conveying direction and the kicking portion 330K is provided in the sheet ejecting direction. The rollers 330b are not caught by the rollers 330b and are smoothly conveyed onto the surface formed by the slide guides R301 and L302. As a condition for this, FIG.
As shown in, the outer peripheral surface of the upstream portion of the right kick roller 330R needs to be formed in a continuous arc or taper shape. Similar to the second sheet, the third and subsequent sheets are repeatedly aligned to align a predetermined number of sheets, and then the stapling operation is performed.

When the stapling operation is completed in this way, the arm 331 rotates clockwise, and the discharge upper roller 330a pivotally supported by the arm 331 moves downward to form the discharge roller pair 330. At the same time, the drive is connected to both rollers of the discharge roller pair 330 and the discharge upper roller 330.
a and the lower discharge roller 330b start to rotate. By this operation, the bundle of sheets S is nipped by the upper discharge roller 330a and the lower discharge roller 330b and conveyed onto the surface formed by the slide guide R301 and the slide guide L302.

When the bundle of sheets S is completely discharged from the discharge roller pair 330, as shown in FIG.
When is driven to rotate, the slide guide R301 and the slide guide L302 move outward.

Further, the stapled sheet bundle drops downward as shown in FIG. 4 when the distance between the supported slide guides 301 and 302 becomes close to or wider than the width of the sheet. . As a result, the sheet bundle falls to the sheet stacking unit 325 of the sheet post-processing device,
Loaded.

In the present embodiment, the right kicking roller 330R and the left kicking roller 330L have a bilaterally symmetrical shape, which is also effective when the aligning direction perpendicular to the sheet conveying direction is opposite to that of the present embodiment. However, the taper portion where the sheet does not contact may be deleted.

The present invention has been described above as the first embodiment, but the present invention can provide a sheet post-processing apparatus having good sheet alignment.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. The same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.
FIG. 8 is an explanatory diagram of the right kick roller according to the second embodiment.

The right kicking roller 440 of this embodiment is similar to that of the first embodiment in that the kicking roller portion of the discharging lower roller 330b is formed in the shape of a cylinder instead of the rib shape as in the first embodiment. It has an effect.

According to this structure, as compared with the rib structure of the first embodiment, all the portions that come into contact with the sheet are formed by surfaces, so that the rib structure has a tapered portion in comparison with the first embodiment. As a result, it is possible to handle even a sheet with a large curl, and it is possible to reduce the catching of the sheet. Further, the left kicking roller has a symmetrical shape.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory diagram of the right kicking roller of the third embodiment, and the arrows indicate the sheet conveying direction.

In the kicking roller of the above-mentioned embodiment, the diameter of the roller is increased toward the end of the sheet in order to give the thin sheet a rigidity. However, the right kicking roller 550 of the present embodiment is a type in which the diameters of both ends of the kicking roller portion do not change when the number of sheets stacked in the sheet stacking portion is small. When the number of stacked sheets is small, it is not necessary to increase the diameter of the rollers on both ends in this way. That is, the cross-sectional shapes may be the same.

According to this structure, since the shape of the roller can be simplified, the structure of the mold can be simplified.

(Other Embodiments) In the above-described embodiments, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this, and may be a facsimile machine, a copying machine or the like.

[0051]

As described above, in the present invention, the discharge roller pair for discharging the sheet, which is composed of the upper roller and the lower roller which can be separated from each other, and the upper roller of the discharge roller pair are provided. An intermediate stacking unit that is formed by retreating and temporarily stacks sheets, and an aligning unit that is in contact with the side surface in the width direction of the sheet, is movable in the width direction of the sheet, and aligns the sheets on the intermediate stacking unit. Of the pair of discharge rollers, at least a part of the outer peripheral surface of the lower roller is provided with a kicking-out portion where the downstream side in the sheet conveying direction kicks out the rear end of the sheet, and the conveying direction upstream side from the apex of the kicking-out portion. Taper so that the turning radius decreases toward, or
Since it is configured in an arc shape, it is possible to improve the consistency of the sheet when the sheet is post-processed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an overall configuration of a sheet post-processing apparatus and an image forming apparatus.

FIG. 2 is an enlarged view of a sheet post-processing device 300.

FIG. 3 is an operation explanatory view of the slide guide at each position of the seat.

FIG. 4 is an operation explanatory view of a slide guide.

FIG. 5 is a perspective view of a kick roller.

FIG. 6 is an explanatory diagram of ribs of a kick roller.

FIG. 7 is a cross-sectional view of a kick roller.

FIG. 8 is an explanatory diagram of a right kicking roller according to the second embodiment.

FIG. 9 is an explanatory diagram of a right kick roller according to a third embodiment.

FIG. 10 is a perspective view of a sheet post-processing device.

FIG. 11 is an explanatory diagram of an intermediate stacking unit 300B.

FIG. 12 is an explanatory diagram of a conventional sheet post-processing device.

[Explanation of symbols]

H ... Staple M: Jogger motor R ... Laura S ... sheet a ... rib b ... rib c ... rib d ... rib 100… Printer body 100A ... Device body 101 ... Image forming unit 120… Fixer 125… FD discharge part 130… Ejection roller 150 ... Flapper 200… Feed cassette 300… Sheet post-processing equipment 300A ... Casing part 300B ... Intermediate loading section 300C ... Bent 301… Slide guide R 302… Slide guide L 303… Reference pin R 304 ... Reference pin L 305 ... Reference pin 320… Staple rollers 322 ... Paddle 323… Reference wall 325 ... Loading section 330… Ejection roller pair 330K ... kicking part 330L ... Left kicking roller 330R ... right kicking roller 330a ... Discharging upper roller 330b ... Lower discharging roller 331 ... Arm 350… Paddle shaft 363… Inlet roller pair 390… Entrance sensor 440… Right kicking roller 550… Right kicking roller

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junichi Sekiyama             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Hironobu Ata             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Yasuyoshi Hayakawa             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 3F049 CA02 CA04 CA05 DA11 DA12                       LA01 LB03                 3F054 AA01 AB01 AC02 AC03 AC05                       BA04 BG04 BG11 BH14 BJ05                       DA01                 3F108 GA02 GA03 GA04 GB01 HA02                       HA39

Claims (7)

[Claims] 1. A sheet post-processing device having post-processing means for post-processing a conveyed sheet, comprising a top roller and a bottom roller which can be separated from each other, and a discharge roller for discharging the sheet. A pair, an upper roller of the pair of discharge rollers is retracted, an intermediate stacking unit for temporarily stacking sheets, and a width direction side surface of the sheet, and movable in the sheet width direction, An aligning unit that aligns the sheets on the intermediate stacking unit, and at least a part of an outer peripheral surface of the lower roller of the discharge roller pair has a kicking-out unit that kicks out a rear end of the sheet at a downstream side in the sheet conveying direction. The sheet post-processing apparatus is provided with a taper shape or an arc shape in which the radius of rotation decreases from the apex of the kicking portion toward the upstream side in the transport direction. 2. A sheet post-processing apparatus having post-processing means for post-processing a conveyed sheet, comprising a top roller and a bottom roller which can be separated from each other, and a discharge roller for discharging the sheet. A pair, an aligning unit that supports the sheet discharged from the pair of discharge rollers, is in contact with a side surface in the width direction of the sheet, is movable in the width direction of the sheet, and aligns the sheet on the intermediate stacking unit; An intermediate stacking unit that is formed when the supporting surface of the aligning unit moves inward of the width of the sheet and the upper roller of the discharge roller pair retracts, and temporarily stacks the sheet; Of the pair of discharge rollers, at least a part of the outer peripheral surface of the lower roller is provided with a kick-out portion that kicks out the rear end of the sheet on the downstream side in the sheet conveyance direction, and the radius of rotation from the apex of the kick-out portion toward the upstream side in the conveyance direction. Is reduced So that a tapered or sheet post-processing apparatus characterized by being configured in an arc shape. 3. The sheet post-processing apparatus according to claim 1, wherein the drive unit that drives the discharge roller pair drives the discharge roller pair in accordance with the operation of retracting the upper roller. A sheet post-processing device that is released. 4. The sheet post-processing apparatus according to claim 1, wherein the pair of discharge rollers has a comb tooth structure. 5. The sheet post-processing apparatus according to claim 1, wherein the rollers at both ends of the lower roller are separated from a sheet conveyance center in a direction orthogonal to the sheet conveyance direction. A sheet post-processing apparatus, which is a stiffening member having an increased outer peripheral surface of a roller. 6. The sheet post-processing apparatus according to claim 5, wherein the stiffening member is formed in a rib shape, and the side facing the sheet aligning direction with respect to the direction orthogonal to the sheet conveying direction. A sheet post-processing apparatus, wherein the corners arranged in the sheet are subjected to R processing or chamfering. 7. An image forming apparatus comprising: an image forming section for forming an image such as a toner image on a conveyed sheet; and a post-processing section for performing a post-processing on the sheet on which the image is formed by the image forming section, An image forming apparatus, wherein the post-processing unit is the sheet post-processing apparatus according to any one of claims 1 to 6.