JP5322490B2 - Sheet discharging apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet ejection device and an image forming apparatus capable of securing a sheet ejection capacity while reducing stiffening noise. <P>SOLUTION: Flanges 203b, 205b of first and second elasticizing rollers 203, 205 stiffen a sheet to be transferred, in a supported state so as to be sandwiched, by first and second drive rollers 202, 204 and the first and second stiffening rollers 203, 205. The flange 205b of the second stiffening roller 205 disposed upstream in the sheet ejection direction is formed smaller in diameter than the flange 203b of the first stiffening roller 203 disposed downstream in the sheet ejection direction, thereby gradually increasing stiffening forces applied by the flanges 203b, 205b to the sheet. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a sheet discharging apparatus and an image forming apparatus, and more particularly to a sheet discharging apparatus with a waist attached.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine thereof, an image forming unit that forms an image on a sheet, and a sheet stacking unit that discharges a sheet on which an image is formed by a pair of discharge rollers A sheet discharge device is mounted on the sheet.

  In such an image forming apparatus, when an image is formed on a sheet, an electrostatic latent image is first formed on the surface of the photosensitive drum provided in the image forming unit, and then the electrostatic latent image is developed with toner. As a result, a toner image is formed on the surface of the photosensitive drum. Next, the toner image is transferred onto the sheet, and then the toner image is fixed to the sheet by heating and pressurizing the sheet on which the toner image has been transferred in the fixing unit. Then, the sheet on which the toner image is fixed as described above is discharged from the sheet discharge port to the sheet stacking unit by a pair of discharge rollers provided in the sheet discharge device.

  By the way, when the sheet is heated at the fixing unit, the sheet may be curled. When the curl is generated in this way, the sheet stacking performance of the sheet stacking unit is deteriorated, and the trailing end of the discharged sheet is the sheet discharge port. There is a case where a paper jam occurs.

  Therefore, in the conventional sheet discharging apparatus, for example, when discharging a sheet, the sheet is waved in a direction perpendicular to the sheet discharging direction (hereinafter, referred to as a width direction) by a pair of discharge rollers so as to have a wave shape in the width direction. (See Patent Document 1). And by making the sheet into a wave shape in this way, the curl of the sheet is eliminated, and the sheet is seated, thereby increasing the rigidity and discharging the sheet, thereby improving the sheet stackability. .

  FIG. 21 is a perspective view showing a configuration of a pair of paper discharge rollers provided in such a conventional sheet discharge device. The pair of paper discharge rollers 119 is in pressure contact (contact) with the drive roller 119A and the drive roller 119A. And a driven roller 119B that is driven to rotate. The drive roller 119A includes a rubber drive roller portion 119a that is fixed to the drive shaft 121 at a predetermined interval.

  The driven roller 119B includes a driven roller portion 119b that is fixed to the shaft 122 at a predetermined interval and is in pressure contact with the driving roller portion 119a of the driving roller 119A. Here, flange portions 119c having a diameter larger than that of the driven roller portion 119b are integrally formed at both ends of the driven roller portion 119b. In FIG. 21, reference numerals 123 and 124 denote conveyance guides that form a conveyance path between a fixing unit (not shown) and the paper discharge roller pair 119.

  Then, after the toner image is fixed by the fixing unit, the sheet conveyed from the direction of arrow C reaches the pair of discharge rollers 119 while being guided by the conveyance guides 123 and 124. When passing through the paper discharge roller pair 119, the sheet has a wave shape in the width direction by the flange portion 119c and the drive roller portion 119a of the driven roller portion 119b as shown in FIG. As a result, the rigidity of the sheet S can be increased, and the sheet discharge performance (sheet flyability) for pushing the sheet S outward can be improved.

JP-A-10-139251

  However, in such a conventional sheet discharging apparatus and an image forming apparatus including the sheet discharging apparatus, when the sheet is seated in a wave shape, a deformation sound (hereinafter referred to as a seating sound) accompanying the deformation of the sheet is generated. End up. In addition, the seating noise increases the sheet discharging performance (sheet flying performance), so that the diameter of the flange portion 119c is increased, the sheet discharging speed of the sheet is increased, or the basis weight of the sheet is large. growing.

  Since the sheet discharge roller pair 119 is provided at the sheet discharge port of the image forming apparatus, when such a back-up sound is generated, the operator and users around the image forming apparatus recognize it as noise, There is a problem of feeling uncomfortable.

  On the other hand, for example, in order to ensure the sheet discharge performance of a sheet having a large basis weight, it is necessary to increase the seating amount (wave shape size) of the sheet. For this reason, the diameter of the flange portion 119c may be increased. .

  Here, FIG. 23 is a diagram in which the relationship between noise and the amount of seating is experimentally obtained. As shown in FIG. 23, the noise when the seating amount is 1 mm or less is small, and the seating is firmly performed. For this reason, when the seating amount is about 2 mm, the noise becomes very large. This phenomenon is the same even if the paper type is different.

  As is clear from this experiment, noise increases when the diameter of the flange portion 119c is increased to increase the seating amount of the seat in order to ensure sheet discharge performance. Further, when the diameter of the flange portion 119c is increased, the large-diameter flange portion 119c prevents the sheet from entering the nip that is the contact portion between the driven roller portion 119b and the driving roller portion 119a, and jamming occurs. There is a case.

  Therefore, the present invention has been made in view of such a current situation, and an object thereof is to provide a sheet discharge apparatus and an image forming apparatus that can reduce seating noise and ensure sheet discharge performance. Is.

The present invention is a sheet discharge device that discharges a sheet on which an image is formed as a wave shape in a width direction orthogonal to the sheet discharge direction, and includes a first roller shaft and a plurality of coaxially provided on the first roller shaft A first roller having a roller body, and a second roller shaft and a second roller provided coaxially with the second roller shaft and having a plurality of roller bodies in contact with the roller body of the first roller. , A plurality of roller pairs for discharging the sheet in a wave shape are arranged in the sheet discharging direction, and the sheet discharging direction so as to gradually increase the force to wave the sheet applied to the sheet by the roller pair when discharging the sheet The number of the roller main body of the first roller and the roller main body of the second roller of the roller pair arranged on the upstream side is set to the first roller of the roller pair arranged on the downstream side in the sheet discharge direction. It is characterized in that the la of the roller body and less than the number of the roller body of the second roller.

  As in the present invention, at the time of sheet discharge, the configuration is such that the force applied to the sheet is gradually increased by the roller pair that discharges the sheet as a wave shape, thereby reducing the seating noise. At the same time, sheet discharge performance can be secured.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a sheet discharge device according to a first embodiment of the present invention. The image forming apparatus 100 includes an image forming apparatus main body 100A and an image reading apparatus 100B that is provided on the upper part of the image forming apparatus main body and reads a document image.

  Reference numeral 100D denotes a sheet feeding device that feeds the sheet S stored in the sheet feeding cassette 114. The sheet feeding apparatus 100D separates the sheet S fed by the sheet feeding roller 120 and the sheet S fed by the sheet feeding roller 120 into only one sheet. A separation roller pair 111 is provided.

  The image forming apparatus main body 100A is provided with an image forming unit 100C that forms an image on the sheet S. The image forming unit 100C includes a photosensitive drum 101 that is an image carrier that is rotatable in the direction of an arrow, a charger 108, a developing unit 129, a transfer device 115, and the like disposed around the photosensitive drum 101. ing.

  The image reading apparatus 100B includes a scanner unit 100E including an optical lamp 102, mirrors 103 to 107a and 107b, and a lens 109. When reading a document image, the scanner unit 100E is scanned in the direction of the arrow while irradiating a document (not shown) set on the platen glass 110 with light from the lamp 102.

  When the scanner unit 100E scans while irradiating light in this way, the reflected light from the document forms an image on the outer peripheral surface of the photosensitive drum 101 rotating in the direction of the arrow through the mirrors 103 to 107a and 107b and the lens 109. Is done. Here, the surface of the photosensitive drum 101 is uniformly charged by a charger 108 after being neutralized by a pre-exposure lamp (not shown).

  Then, by irradiating the surface of the photosensitive drum with the surface charged in this manner, an electrostatic latent image corresponding to the scanned light is formed on the surface of the photosensitive drum. Thereafter, the electrostatic latent image on the photosensitive drum is visualized as a toner image by the toner supplied from the developing device 129.

  On the other hand, in parallel with such a toner image forming operation, the sheet S stored in one of the cassettes 114 and the manual sheet feeding unit 121 is fed. Here, when the sheet S is fed from the cassette 114, the sheet S stored in the cassette 114 is fed by the sheet feeding roller 120. Then, after the sheet S is separated into only one sheet by the separation roller pair 111, the sheet S is abutted against the nip portion of the registration roller 113 in a stopped state by the sheet conveying roller 112 and stops. Here, the inclination of the sheet S is corrected by stopping the sheet S against the registration roller 113 in the stopped state.

  Next, after correcting the inclination of the sheet S, the registration roller 113 is rotated at a timing at which the toner image can be transferred to a desired position on the sheet S, and the transfer unit configured by the photosensitive drum 101 and the transfer device 115 is rotated. Transport to. As a result, the toner image formed on the photosensitive drum 101 is transferred onto the conveyed sheet in this transfer unit.

  Next, when the transfer of the toner image is completed, the sheet S to which the toner image has been transferred is conveyed to the fixing unit 117A having the fixing roller pair 117 by the conveying belt 116, and the toner image is formed by the heat and pressure of the fixing roller pair 117. It is fixed on the surface of S. Thereafter, the sheet S is separated from the fixing roller pair 117 by the separation claw 118, and is discharged onto the paper discharge tray 120 outside the image forming apparatus main body by the sheet discharge device 201.

  FIG. 2 is a perspective view showing the overall configuration of the sheet discharge apparatus 201 according to the present embodiment, and FIG. 3 is a side view thereof. 2 and 3, reference numerals 210 and 211 denote conveyance guides for guiding the sheet S conveyed from the fixing unit 117A to the sheet discharge device 201.

  Reference numerals 202 and 204 denote first and second driving rollers which are first rollers. The first and second drive rollers 202 and 204 are made of rubber and are coaxially fixed to the drive roller shafts 206 and 208, which are first roller shafts rotating in the direction of arrow D, at a predetermined interval. Roller portions 202a and 204a which are roller bodies are provided.

  Reference numerals 203 and 205 denote first and second waist rollers which are second rollers that rotate following the rotation of the first and second drive rollers 202 and 204, respectively. The first and second seating rollers 203 and 205 are made of rubber that is coaxially fixed to the seating roller shafts 207 and 209, which are second roller shafts rotating in the direction of arrow E, at predetermined intervals. This is provided with seating roller portions 203a and 205a, which are the roller bodies.

  The first and second waist rollers 203 and 205 are moved in pressure contact (contact) with the roller portions 202a and 204a of the first and second drive rollers 202 and 204, so that the first and second waist rollers 203 and 205 are And it rotates following the rotation of the second drive rollers 202 and 204.

  The first drive roller 202 located on the downstream side in the sheet discharge direction and the first waist roller 203 pressed against the first drive roller 202 constitute a first discharge roller pair 201A. Further, the second drive roller 204 positioned on the upstream side in the sheet discharge direction and the second waist roller 205 pressed against the second drive roller 204 constitute a second discharge roller pair 201B. In other words, in the present embodiment, the sheet discharge device 201 includes two discharges, a first discharge roller pair 201A located on the downstream side in the sheet discharge direction and a second discharge roller pair 201B located on the upstream side in the sheet discharge direction. A pair of paper rollers are provided side by side in the sheet discharge direction.

  On the other hand, flange portions 203b and 205b, which are waist portions having a radius larger than the radius r1 of the waist roller portions 203a and 205a, are integrally formed at both ends in the axial direction of the waist roller portions 203a and 205a. . Further, by providing such flange portions 203b and 205b on the seating roller portions 203a and 205a, when the sheet S is conveyed, the sheet can be wave-shaped in the width direction as shown in FIG. Thus, the seat S can be seated. At the same time, it is possible to improve the sheet discharge performance (sheet flyability) for pushing the sheet S toward the outside of the apparatus.

  Incidentally, as shown in FIG. 3, the flange radius r1 of the flange portion 203b of the first waist roller 203 is formed to be larger than the flange radius r2 of the flange portion 205b of the second waist roller 205. A difference in the amount of seating occurs due to the difference between the radii r1 and r2 of the flange portions 203b and 205b and the radius r3 of the seating roller portions 203a and 205a.

  The difference between the radius r3 of the seating roller portions 203a and 205a and the radii r1 and r2 of the flange portions 203b and 205b differs depending on the type of the sheet S to be used, the sheet discharge speed, the configuration / temperature of the fixing unit 117A, and the like. In the present embodiment, this difference is set to be about 1 mm for the first paper discharge roller pair 201A and about 0.5 mm for the second paper discharge roller pair 201B.

  As a result, the deformation amount of the sheet S when passing through the first paper discharge roller pair 201A (ie, the amount of seating) is about 0 compared with the deformation amount of the sheet S when passing through the second paper discharge roller pair 201B. .5mm larger. In other words, the second paper discharge roller pair 201B is less stiff than the first paper discharge roller pair 201A.

  When the sheet S passes through the sheet discharge device 201 configured as described above, the sheet S is first subjected to a difference between the radius r3 of the seating roller portion 205a and the radius r2 of the flange portion 205b by the second discharge roller pair 201B. It is seated by the amount according to it.

  Thereafter, the sheet S enters the first paper discharge roller pair 201A, and when passing through the first paper discharge roller pair 201A, the difference between the radius r3 of the seating roller portion 203a and the radius r1 of the flange portion 203b. It is seated by the amount according to it. Then, the sheet seated by the second sheet discharge roller pair 201B is seated again by the first sheet discharge roller pair 201A, so that it is necessary to secure the sheet discharge performance outside the apparatus. Is made.

  As described above, in the present exemplary embodiment, necessary seating on the sheet S is performed stepwise and gradually in two steps by the first discharge roller pair 201A and the second discharge roller pair 201B. I am doing so. In addition, by performing the seating in two times (a plurality of times) in this manner, it is possible to prevent abrupt deformation of the sheet, and thereby the first and second paper discharge roller pairs 201A and 201B. The seating noise generated from the seat S when passing through can be reduced.

  In addition, the sheet S is seated in two steps and the radius r2 of the flange portion 205b of the second discharge roller pair 201B is reduced, whereby the sheet S that has been transported after fixing is discharged to the second discharge. A paper jam when entering the roller pair 201B can be prevented.

In addition, the experiment which calculates | requires the relationship between the increase in the flange diameter of a back roller part and a back noise was conducted using plain paper with a basis weight of about 60 g / m ² . In this experiment, the amount of waisting by the waisting roller was up to 2 mm, the conveyance speed of the sheet S was 450 mm / s, and the pressing force against the driving roller was about 3N.

  As a result of this experiment, it was found that the increase in the flange diameter of the back roller is proportional to the back noise. Specifically, it was found that when the amount of sitting is small, the seating sound is substantially constant, but when the amount of sitting is increased to some extent, the seating sound increases with an increase in the amount of sitting.

  Accordingly, also from this experiment, the sheet S is deformed by reducing the deformation amount (backing amount) of the sheet S in the first and second paper discharge roller pairs 201A and 201B so as not to cause sudden deformation of the sheet. It became clear that the increase in sound could be prevented.

  As described above, in this embodiment, the sheet is seated in two steps by the first and second paper discharge roller pairs 201A and 201B. And when comprised in this way, the seating sound of the sheet | seat S generate | occur | produces twice, but generation | occurrence | production of a seating sound can be disperse | distributed temporally. Further, since the amount of back-up on the first and second paper discharge roller pairs 201A and 201B can be reduced, the back-up sound at the time of back-up on the first and second paper discharge roller pairs 201A and 201B can be reduced. Can be reduced.

  In other words, the seating of the seat is performed in two steps, and the seating force, which is the force that makes the seat corrugated into the seat, is configured to gradually increase (stepwise). It is possible to reduce waist noise (noise) perceived by a person or a surrounding user. Further, the seating noise can be reduced and the sheet discharge performance can be ensured.

  In the above description, the case where two pairs of paper discharge rollers 201A and 201B are provided as an example when a plurality of paper discharge roller pairs are arranged in the sheet discharge device 201 has been described. Three or more pairs of paper discharge rollers may be provided.

  FIG. 5 is a diagram illustrating a case where, for example, three sheet discharge roller pairs are arranged in parallel in the sheet discharge direction on the sheet discharge apparatus 201. In FIG. 5, 201C is a third paper discharge roller pair provided on the upstream side of the first and second paper discharge roller pairs 201A and 201B in the sheet discharge direction, and the third paper discharge roller pair 201C is a third paper discharge roller pair 201C. The driving roller 214 and a third waist roller 212 that presses against the driving roller 214 are configured.

  The third drive roller 214 includes a roller portion 214a that is a rubber roller body that is fixed to a drive roller shaft 215 that rotates in the direction of arrow D at a predetermined interval. The third waist roller 212 includes a waist roller portion 212a which is a rubber roller body fixed to a waist roller shaft 213 rotating in the direction of arrow E at a predetermined interval. Flange portions 212b are integrally formed at both ends of the seating roller portion 212a.

  In this case, the flange radius r1 of the flange portion 203b of the first waist roller 203 is formed to be larger than the flange radius r2 of the flange portion 205b of the second waist roller 205. The flange radius r2 of the flange portion 205b of the second waist roller 205 is formed to be larger than the flange radius r4 of the flange portion 212b of the third waist roller 212.

  That is, in the first to third paper discharge roller pairs 201A to 201C, the flange diameter of the waist roller of the paper discharge roller pair on the downstream side in the sheet discharge direction is set to be equal to that of the waist roller of the paper discharge roller pair on the upstream side. It is formed to be larger than the flange diameter. With this configuration, it is possible to achieve further noise reduction as compared with the case where two paper discharge roller pairs are provided as shown in FIG. In the description so far, the flange portion is provided on the seating roller which is one of the driving roller and the seating roller (driven roller), but the flange portion is provided on the driving roller which is the other of the driving roller and the driven roller. May be.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a perspective view showing the overall configuration of the sheet discharge apparatus according to the present embodiment. In FIG. 6, the same reference numerals as those in FIGS. 2 and 5 described above indicate the same or corresponding parts.

  Here, in this embodiment, a plurality of (six) drive rollers 202 constituting the first paper discharge roller pair 201A are fixed to the drive roller shaft 206 at a predetermined interval. A roller portion 202a is provided. The first waist roller 203 constituting the first paper discharge roller pair 201A includes a plurality of (six) rubber waist roller portions 203a fixed to the waist roller shaft 207 at a predetermined interval. I have.

  The second drive roller 204 (see FIG. 5) constituting the second paper discharge roller pair 201B includes a plurality of (four) rubber roller portions 204a fixed to the drive roller shaft 208 at a predetermined interval. ing. The second seating roller 205 constituting the second paper discharge roller pair 201B includes a plurality of (four) rubber seating roller portions 205a fixed to the seating roller shaft 209 at a predetermined interval. I have.

  The third drive roller 214 (see FIG. 5) constituting the third paper discharge roller pair 201C includes a plurality of rubber rollers 215a fixed to the drive roller shaft 215 at a predetermined interval (two). ing. In addition, the third waist roller 212 constituting the third paper discharge roller pair 201C includes a plurality of (two) rubber waist roller portions 212a fixed to the waist roller shaft 213 at a predetermined interval. I have.

  That is, in the sheet discharge device 201 according to the present embodiment, the number of roller portions provided in the axial direction from the upstream side in the sheet discharge direction to the downstream side in the sheet discharge direction is increased to 2, 4, and 6. Is configured to do. With this configuration, when the sheet S passes through the sheet discharge device 201, the sheet S sequentially passes from a pair of discharge rollers having a small number of seating portions including a driving roller portion and a seating roller portion. To come.

  Then, by sequentially passing through the pair of discharge rollers having a small number of seating portions in this manner, the seating of the sheet can be performed in stages, and the generation of the seating sound can be dispersed in time. This can reduce the seating noise. In addition, paper jams can be prevented, and the number of seating rollers and driving rollers can be reduced, so that the cost of the paper discharge roller pair can be reduced.

  Note that the number of seating portions depends on the transportability of the sheet S passing through the paper discharge roller pair (for example, whether there is a paper jam) depending on the type of the sheet S used and the shape of the transport guides 210 and 211 near the paper discharge roller pair. ) May be determined as appropriate. In this embodiment, three paper discharge roller pairs are provided, but the number of paper discharge roller pairs may be determined as appropriate.

  Furthermore, in this embodiment, the roller portions of the second and third paper discharge roller pairs 201B and 201C are increased from the width direction end side toward the width direction center side toward the downstream side in the sheet discharge direction. However, it is not limited to this form. For example, as shown in FIG. 7, the number of roller portions of the second and third paper discharge roller pairs 201B and 201C increases from the center in the width direction toward the end in the width direction as going downstream in the sheet discharge direction. You may make it make it.

  Next, a third embodiment of the present invention will be described.

  FIG. 8 is a side view showing the configuration of the sheet discharge apparatus according to the present embodiment. In FIG. 8, reference numeral 502 denotes a driving roller, and reference numeral 503 denotes a first waist roller that presses against the driving roller 502 and rotates as the driving roller 502 rotates. Reference numeral 505 denotes a second waist roller that is positioned upstream of the first waist roller 503 in the sheet discharge direction, presses against the drive roller 502, and rotates as the drive roller 502 rotates.

  The drive roller 502 includes a rubber roller portion 502a that is fixed to a drive roller shaft 506 that rotates in the direction of arrow D at a predetermined interval. The first waist roller 503 is provided with a rubber waist roller portion 503a fixed to a waist roller shaft 507 rotating in the direction of arrow E at a predetermined interval. Flange portions 503b are integrally formed at both ends of the portion 503a.

  The second waist roller 505 is provided with a rubber waist roller portion 505a fixed to a waist roller shaft 509 rotating in the direction of arrow E at a predetermined interval, and this waist roller portion 505a. The flange portions 505b are integrally formed at both ends of the.

  With this configuration, it is possible to configure a discharge roller pair similar to the first discharge roller pair as shown in FIG. The drive roller 502 and the second waist roller 505 can constitute a discharge roller pair similar to the second discharge roller pair as shown in FIG.

  As a result, as in the first embodiment described above, the seating of the seat can be performed in stages and the generation of the seating sound can be dispersed over time. In addition, the amount of back-up can be reduced by performing the back-up separately by the drive roller 502 and the first back-up roller 503 and the drive roller 502 and the second back-up roller 505. The seating sound generated with each deformation can be reduced.

  Further, in the present embodiment, the flange radius r7 of the flange portion 503b of the first waist roller 503 is formed to be larger than the flange radius r8 of the flange portion 505b of the second waist roller 505. Accordingly, the amount of seating by the driving roller 502 and the second seating roller 505 can be reduced, so that the sheet S that has been transported after fixing has been nipped between the driving roller 502 and the second seating roller 505. It is possible to prevent paper jam when entering the printer. This embodiment is an effective configuration when applied to, for example, a small printer provided with curved conveyance guides 210 and 211.

  Further, in the case of the configuration of the present embodiment, the number of driving rollers 502 can be reduced, so that the cost of the sheet discharge device 201 can be reduced. In this embodiment, the pair of paper discharge rollers is composed of one drive roller 502 and two seating rollers 503 and 505. However, the present invention is not limited to this configuration, and there are three or more rollers. A waist roller may be provided.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 9 is a diagram illustrating a configuration of the sheet discharging apparatus according to the present embodiment. In FIG. 9, reference numeral 2 denotes a pair of paper discharge rollers provided in the sheet discharge device 201, and the pair of paper discharge rollers 2 includes a driving roller 4 and a pressure roller 5 that presses against the driving roller 4. Reference numeral 3 denotes a drive shaft to which the drive roller 4 is attached. The drive shaft 3 is rotated by a drive source (not shown), and a stepped shape 3A having a large diameter is formed at a substantially central portion.

  Here, the drive roller 4 includes two rubber-made drive roller portions 4a attached to the drive shaft 3, and a rubber-made auxiliary roller portion having a hollow structure provided on both sides in the width direction of the two drive roller portions 4a. 4b, 4c.

  A key groove (not shown) is formed in the central hole of the drive roller portion 4a, and a key groove (not shown) shorter than the width of the drive roller portion 4a is formed on the drive shaft 3, and the key groove A key (not shown) for restricting rotation is driven. As a result, the drive roller portion 4 a can move in the thrust direction of the drive shaft 3 and can rotate with the drive shaft 3. In the present embodiment, the keyway method is used to restrict the rotation of the drive roller unit 4a, but a spline shaft may be used.

  On the other hand, the auxiliary roller portions 4b and 4c are provided separately from the drive roller portion 4a, and are slidable on the drive shaft 3 in the thrust direction and are held rotatably. The movement of the auxiliary roller portion 4b (drive roller 4) on the drive shaft center side is restricted by the stepped shape 3A at the substantially center portion of the drive shaft 3. In addition, a sliding member such as a resin washer formed by a PET sheet (not shown) is inserted between the driving roller portion 4a and the auxiliary roller portions 4b and 4c to reduce the load in the thrust direction during rotation. ing.

  In the present embodiment, the driving roller unit 4a is made of a material such as butyl rubber or CR rubber having a rough surface to reliably convey the sheet by frictional force, and the auxiliary roller units 4b and 4c have a function of deforming the sheet. To a rubber material having a good surface roughness. In the present embodiment, the auxiliary roller portions 4b and 4c have a hollow structure so as to be easily deformed when pressure is applied in the axial direction as will be described later.

  The pressure roller 5 is used to clamp and convey the sheet S while being in pressure contact with the driving roller portion 4a. The pressure roller 5 is formed of a resin having good slidability such as POM material, and is rotatably supported on the shaft 6. ing. The drive roller unit 4a and the pressure roller 5 need not be limited to the above-mentioned materials. The drive roller unit 4a is molded from a resin having good slidability such as POM, and the opposite pressure roller 5 is made of rubber. It may be a material.

  A side pressure cam 7 is slidably attached to the drive shaft 3. The side pressure cam 7 has a hole 7e inserted in a fixing member (not shown) provided in the image forming apparatus main body 100A (sheet discharge apparatus main body). The rotation is regulated by doing so. A cam surface shown in FIG. 10 described later is formed on the side surface of the side pressure cam 7.

  A thrust bearing 8 is disposed between the auxiliary roller portion 4 c and the side pressure cam 7. Reference numeral 9 denotes a side pressure follower that is rotated by driving means described later. This side pressure follower 9 is rotatably held by the drive shaft 3 and has an eccentric protrusion 9 a that presses against the cam surface of the side pressure cam 7. ing. Further, the side pressure follower 9 is formed with a groove 9b for driving transmission, and rotation transmission is performed by a driving transmission belt described later.

  Here, when the side pressure follower 9 is rotationally driven by a driving means described later, the protrusion 9 a formed on the side pressure follower 9 rotates around the drive shaft 3. A stopper 3a is provided at the end of the drive shaft 3. This stopper 3a prevents the paper discharge roller pair 2 from slipping and the auxiliary roller portions 4b and 4c are slightly deformed as will be described later. At this time, the auxiliary roller portions 4b and 4c have a stopper function for holding a slightly deformed state.

  FIG. 10 is a diagram showing the configuration of the side pressure cam 7. As shown in FIG. 10, a cam surface 7A is formed on the side surface of the side pressure cam 7, and two flat portions having steps are formed on the cam surface 7A. 7a, 7b and two inclined cam surfaces 7c, 7d connecting the two flat portions 7a, 7b are formed.

  FIG. 11 is a diagram for explaining a drive system of the sheet discharge apparatus. In FIG. 11, reference numeral 10 denotes a conveyance drive roller that conveys the sheet S to the discharge roller pair 2. The transport drive roller 10 is configured to rotate in the direction of arrow A in the figure by a drive motor 55 shown in FIG. The transport drive roller 10 has a stepped cylindrical shape with a small diameter at the center, and a groove (not shown) around which the drive transmission belt 15 is wound is formed on the outer peripheral surface of the small diameter cylindrical portion at the center. ing.

  Reference numeral 12 denotes a driven roller that is rotatably held by a shaft 13 and presses the conveyance driving roller 10 so as to sandwich and convey the sheet together with the conveyance driving roller 10. The driven roller 12 and the conveyance driving roller 10 constitute a sheet conveyance unit that conveys a sheet to the discharge roller pair 2.

  Reference numeral 14 is an intermediate roller having a stepped cylindrical shape with a large diameter at the center, and is rotatably held on a shaft 15. Further, a groove portion 14a around which the drive transmission belt 16 is wound is formed on the outer peripheral surface of the large-diameter cylindrical portion of the intermediate roller 14, whereby the intermediate roller 14 is decelerated as the conveyance drive roller 10 rotates. It is configured to rotate in the middle arrow B direction.

  Further, a groove portion 14 b is formed on the outer periphery of the small diameter cylindrical portion of the intermediate roller 14. A drive transmission belt 16 is also provided between the groove 14 b of the intermediate roller 14 and the drive transmission groove 9 b provided in the side pressure follower 9, whereby the side pressure follower 10 is rotated along with the rotation of the conveyance drive roller 10. 9 rotates in the direction of arrow C in the figure.

  In FIG. 11, 17 and 18 are sheet guides formed of a resin material for appropriately guiding the sheet to the paper discharge roller pair 2. Further, on the upstream side of the conveyance driving roller 10 and the driven roller 12 in the sheet conveyance direction, a position detection sensor 56 as a sheet position detection unit shown in FIG.

  FIG. 12 is a timing chart showing the driving timing of the sheet discharging apparatus having such a configuration. 12, a on the vertical axis is an output signal from the position detection sensor, b is a driving voltage of the conveyance driving roller 10, c is a driving voltage of the driving roller 4 of the paper discharge roller pair 2, and d is a side pressure follower 9. The position of the side pressure cam 7 according to the rotational position is shown.

  On the horizontal axis (time axis), A indicates the time when the position detection sensor detects the passage of the sheet, and B indicates the start-up start time of the conveyance driving roller 10 and the driving roller 4 of the paper discharge roller pair 2. C indicates the time when the sheet is nipped between the paper discharge roller pair 2, and D indicates the time when the next sheet is nipped between the paper discharge roller pair 2.

  FIG. 13 is a control block diagram for controlling the sheet discharging operation of the sheet discharging apparatus. In FIG. Reference numeral 52 denotes a control circuit unit having a memory 53, 55 denotes a drive motor serving as a drive source for the transport drive roller 10 and the drive roller 4, 54 denotes a motor driver for driving the drive motor 55, and 56 denotes a position detection sensor.

  The control circuit 52 considers the sheet conveyance speed in advance and determines the time required for the sheet to reach the drive roller 4 after passing the position detection sensor from the sheet conveyance distance between the position detection sensor 56 and the drive roller 4. The calculation result is stored in the memory 53.

  Next, the sheet discharge operation of the sheet discharge apparatus will be described using the flowchart shown in FIG.

  First, when the sheet is conveyed from the fixing unit 117A, the CPU 51 detects the position of the sheet by the position detection sensor 56 (S100), and when the position detection sensor 56 detects the passage of the sheet (Y in S101), the position detection is performed. A detection signal is sent from the sensor 56 to the CPU 51. This is the timing A in the timing chart shown in FIG.

  Next, based on the detection signal from the position detection sensor 56 and the arrival time information stored in the memory 53 of the control circuit unit 52, the CPU 51 issues a drive command to the motor driver 54 after a predetermined time has elapsed. The drive motor 55 is driven. As a result, the conveyance drive roller 10 (and the drive roller 4 of the paper discharge roller pair 2) rotates (S102). This is the timing B in the timing chart shown in FIG.

  Then, the conveyance driving roller 10 rotates in this manner, whereby the sheet is conveyed and reaches the paper discharge roller pair 2. Further, when the transport drive roller 10 rotates in this way, the rotation of the transport drive roller 10 is transmitted to the side pressure follower 9 via the drive transmission mechanism shown in FIG. 11 described above, and the side pressure follower 9 rotates.

  Here, the side pressure follower 9 is set to a position where the projection 9 a of the side pressure follower 9 presses the flat portion 7 b of the side pressure cam 7 in the initial state when the leading edge of the sheet reaches the driving roller 4. Yes. This is the timing C in the timing chart shown in FIG.

  Here, when the side pressure follower 9 is in the initial state as described above, the side pressure follower 9 hardly acts on the side pressure cam 7 in the thrust direction, so that the auxiliary roller portions 4b and 4c generally maintain the current shape. That is, the pressing portion constituted by the side pressure follower 9 and the side pressure cam 7 does not act on the auxiliary roller portions 4b and 4c. Therefore, as shown in FIG. 15, the diameter of the auxiliary roller portions 4b and 4c is equal to that of the driving roller portion 4a. It is approximately equal to the diameter. As a result, the front end of the sheet easily enters the paper discharge roller pair 2, and jamming or the like is less likely to occur even when a sheet with a large curl is conveyed.

  FIG. 16 shows the position of the protrusion 9a of the side pressure follower 9 relative to the cam surface 7A of the side pressure cam 7 at this time, and the protrusion 9a of the side pressure follower 9 is the cam of the side pressure cam 7 in the initial state. It hangs on the flat portion 7b on the hollow side of the surface 7A. For this reason, the side pressure follower 9 hardly acts on the side pressure cam 7 in the thrust direction.

  Thereafter, when the sheet is further conveyed and the side pressure follower 9 is rotated along with this, the projecting portion 9a passes through the inclined cam surface 7d of the cam surface 7A of the side pressure cam 7, and as shown in FIG. Reach up to. When the protruding portion 9a reaches the protruding flat portion 7a in this way, the side pressure cam 7 is pressed by the side pressure follower 9, and the side pressure cam 7 moves in the direction of the arrow shown in FIG.

  As a result, the side pressure cam 7 is brought into pressure contact with the auxiliary roller portion 4c, and the auxiliary roller portion 4c is moved in the thrust direction and is brought into pressure contact with the driving roller portion 4a. Further, along with this, the driving roller portion 4a moves and further presses against the other auxiliary roller portion 4b. When the auxiliary roller portion 4c is in pressure contact with the drive roller portion 4a and the drive roller portion 4a is in pressure contact with the auxiliary roller portion 4b in this way, the auxiliary roller portions 4b and 4c are connected to the drive shaft 3 as shown in FIG. Elastically deforms (swells) in the radial direction. As a result, the radial lengths of the auxiliary roller portions 4b and 4c are longer than the radial length of the drive roller portion 4a, and the diameters of the auxiliary roller portions 4b and 4c are larger than the diameter of the drive roller portion 4a.

  In this way, when the conveyance of the sheet proceeds, the side pressure cam 7 is moved in the direction of the arrow in the figure by the side pressure follower 9 as shown in FIG. 18, and the auxiliary roller portions 4b and 4c are pressed and elastically deformed accordingly. The diameters of the auxiliary roller portions 4b and 4c are larger than the diameter of the drive roller portion 4a.

  Here, when the diameters of the auxiliary roller portions 4b and 4c are larger than the diameter of the driving roller portion 4a, an overlap occurs between the auxiliary roller portions 4b and 4c. Then, the overlap between the rollers is generated in this manner, whereby the seating on the sheet is started (S103), and then the seated sheet is discharged (S104).

  As described above, in the present embodiment, when the sheet S reaches the paper discharge roller pair 2, as shown in FIG. 15 described above, the diameters of the auxiliary roller portions 4b and 4c and the diameter of the drive roller portion 4a. Is made the same to improve sheet transportability. Further, after the sheet S reaches the paper discharge roller pair 2, the side pressure cam 7 is moved to press the auxiliary roller portions 4b and 4c, and the diameters of the auxiliary roller portions 4b and 4c are gradually made larger than the diameter of the drive roller portion 4a. By increasing the size, the seating force is gradually increased to increase the seating amount. As a result, rapid deformation of the seat is reduced, and noise due to sheet bending is reduced.

  By the way, in order to configure in this way, it is necessary to control the seating amount by moving the side pressure cam 7 in accordance with the timing when the sheet S reaches the pair of discharge rollers 2. Next, the control operation of such a seating amount will be described. Note that the sheet S used in the present embodiment is A4 size (vertical 298 mm × horizontal 210 mm), and the transport direction is horizontal feed (210 mm).

  Here, in the present embodiment, since the sheet conveyance is a specification of lateral feeding, it takes time to feed 210 mm or more per sheet in order to continuously feed the sheets. In view of the design margin, the conveyance roller driving speed is set to 301.44 mm / sec, and the conveyance driving roller 10 and the driving roller 4 are driven at a rotational speed corresponding to 301.44 mm / sec. Here, if the diameters of the drive roller 4 and the conveyance drive roller 10 are both 16 mm, the movement amount per rotation of the drive roller 4 and the conveyance drive roller 10 is 50.24 mm.

  Accordingly, the driving roller 4 and the conveyance driving roller 10 are rotated six times per second, and the sheet discharging roller pair 2 discharges one sheet S by rotating six times in this way. Further, while discharging one sheet S in this manner, the side pressure cam 7 is in a position to press the auxiliary roller portions 4b and 4c.

  In the present embodiment, the drive source of the side pressure follower 9 is not an independent drive source but a drive motor 55, and the rotation of the transport drive roller 10 rotated by the drive motor 55 is decelerated via the intermediate roller 14. To the side pressure follower 9. Here, in the present embodiment, as shown in FIG. 11 described above, the speed is reduced in two steps via the intermediate roller 14, and the reduction ratio between the transport driving roller 10 and the intermediate roller 14 is 3 and intermediate. The reduction ratio between the roller 14 and the side pressure follower 9 is set to 2. As a result, the final reduction ratio becomes 6.

  With this configuration, one sheet S is conveyed every time the driving roller 4 and the conveyance driving roller 10 rotate six times, and a side pressure follower is generated every time the driving roller 4 and the conveyance driving roller 10 rotate six times. 9 rotates once and always returns to a certain position.

  Note that this fixed position is a position where the lateral pressure follower 9 is in an initial state, and the seat S is not seated when in this position. The paper feed speed and the process speed are set under conditions that satisfy this condition. In this embodiment, a mechanism using a belt is used as the drive transmission and reduction mechanism, but a drive transmission and reduction mechanism using a gear may be used.

  As described above, in the present embodiment, when the conveyance driving roller 10 rotates six times, one sheet S is conveyed while being seated, and when the sheet reaches the sheet discharge roller pair 2, the sheet S is seated against the sheet S. The side pressure follower 9 is returned to the initial state so as not to be performed. Further, as described above, in the present embodiment, the cam surface 7A of the side pressure cam 7 is formed with the inclined cam surfaces 7c and 7d, so that the pressure on the side pressure cam 7 by the side pressure follower 9 is gradually increased. become. As a result, the seat is not suddenly deformed, and the seating is gradually performed, so that noise during seating is reduced.

  The seating amount and seating timing with respect to the seat can be changed, for example, by changing the shape of the cam surface of the side pressure cam 7. As a result, it is possible to cope with various seats with a very simple configuration. Is possible. Further, as described above, in the present embodiment, the drive of the side pressure cam 7 is supplied from the conveyance drive roller 10, thereby providing an inexpensive sheet discharge device.

  In addition, if the flat sheet is sandwiched between the rollers and bent suddenly, the roller and the print surface may slip and the print surface may be damaged. By performing the above, slipping of the sheet is reduced and a high-quality image can be obtained.

  In the above description, the auxiliary roller portions 4b and 4c are made of rubber having a hollow structure. However, if the auxiliary roller portions 4b and 4c are easily deformed when pressure is applied in the axial direction, the auxiliary roller portions 4b and 4c are replaced with other elastic members. Alternatively, for example, a sponge or a thin-walled POM resin material may be used. Moreover, although the side pressure cam 7 is moved by the side pressure follower 9, the side pressure cam 7 may be moved by a movable member such as a plunger.

  By the way, in the case of the configuration of the present embodiment, as the distance between the end surface of the pressure roller 5 and the end surfaces of the auxiliary roller portions 4b and 4c becomes narrower, the degree of curvature of the seat for seating increases, and the auxiliary roller portions 4b and 4b, In some cases, a mark due to 4c may be attached to the sheet.

  In such a case, for example, by designing at least one of the rubber hardness (material hardness), the material, the thickness, the shape, etc. of the auxiliary roller portion 4b arranged on the sheet center side, FIG. As shown, the auxiliary roller portion 4b is made more difficult to deform. The other auxiliary roller portion 4c may also be configured to arbitrarily set the degree of elastic deformation, that is, the amount of elastic deformation.

  In addition, by suppressing the deformation of the auxiliary roller portion 4b in this way, the amount of movement of the drive roller portion 4a is also reduced, and thereby the slip between the drive roller portion 4a and the printing surface of the sheet S can be further reduced. . In addition, by making it possible to arbitrarily set the degree of elastic deformation of the auxiliary roller portion 4b as described above, many types can be obtained particularly in the case of a configuration having a plurality of drive rollers 4 provided with the auxiliary roller portion 4b. The optimal seating amount can be set for any seat.

  By the way, in the description so far, the pressing portion is pressed by the side pressure follower (cam follower) 9 that rotates in conjunction with the sheet conveying operation by the sheet conveying portion, and the auxiliary roller portions 4b and 4c are elastically deformed by being pressed by the side pressure follower 9. And a side pressure cam 7 to be operated. However, the present invention is not limited to this. For example, the driving roller 4 may be pressed and moved by a piezoelectric element that extends in the thrust direction when a voltage is supplied.

  Next, a fifth embodiment of the present invention in which the drive roller 4 is moved by a piezoelectric element will be described.

  FIG. 20 is a diagram illustrating a configuration of the sheet discharge device according to the present embodiment. 20, the same reference numerals as those in FIG. 9 described above indicate the same or corresponding parts.

  In FIG. 20, reference numeral 19 denotes a laminated piezoelectric element that is a pressing portion that presses in the axial direction so as to elastically deform the auxiliary roller parts 4 b and 4 c, and electrodes 19 a and 19 b are formed on the end face of the laminated piezoelectric element 19. ing. A power supply unit 20 supplies power from the outside to the piezoelectric element 19, and electrode brushes 20 a and 20 b are formed corresponding to the electrodes 19 a and 19 b of the piezoelectric element 19. Reference numeral 21 denotes a retaining (fixed side) of the piezoelectric element 19.

  When a voltage is supplied to the multilayer piezoelectric element 19 from the power supply unit 20 via the electrode brushes 20a and 20b, the multilayer piezoelectric element 19 extends in the thrust direction indicated by the arrow. In general, since a piezoelectric element has a small amount of deformation, in this embodiment, a necessary amount of change is obtained by using a laminated piezoelectric element in which piezoelectric elements are laminated. The voltage supplied from the power supply unit 20 is such that when the sheet S reaches the paper discharge roller pair 2, the laminated piezoelectric element 19 presses the auxiliary roller units 4 b and 4 c and the conveyance driving roller 10 rotates six times. The voltage is such that the pressure on the auxiliary roller portions 4b and 4c is released.

  As described above, in the present embodiment, the auxiliary roller portions 4b and 4c are elastically moved in the radial direction by changing the length of the laminated piezoelectric element 19 in the thrust direction in accordance with the applied voltage from the power supply unit 20. It can be deformed and seated on the seat. And by comprising in this way, a sudden deformation | transformation of a sheet | seat is lose | eliminated and a seating is performed gradually, Therefore The noise at the time of seating falls.

  In addition to the above configuration, a determination unit (not shown) that determines physical property values such as sheet basis weight and stiffness is provided in the conveyance path or cassette, and the stacked piezoelectric element 19 is provided in accordance with the output signal (output information). You may make it control the voltage to apply. And by comprising in this way, the elastic deformation amount of auxiliary roller part 4b, 4c can be controlled, and the optimal seating according to the kind of sheet | seat can be performed.

  By the way, in the first to fifth embodiments described so far, the case where the sheet discharging apparatus according to the present invention is provided in the image forming apparatus has been described. However, the present invention is not limited to this, and the sheet is discharged. It can also be used in a sheet processing apparatus that performs processing.

1 is a diagram illustrating a configuration of an image forming apparatus including a sheet discharge device according to a first embodiment of the present invention. The perspective view which shows the whole structure of the said sheet | seat discharge apparatus. The side view of the said sheet discharge apparatus. The figure which shows a mode that a wave shape is formed in a sheet | seat by the said sheet | seat discharge apparatus. The side view which shows the other structure of the said sheet | seat discharge apparatus. The perspective view which shows the whole structure of the sheet discharge apparatus which concerns on the 2nd Embodiment of this invention. The perspective view which shows the other structure of the said sheet | seat discharge apparatus. The side view which shows the structure of the sheet discharge apparatus which concerns on the 3rd Embodiment of this invention. The figure which shows the structure of the sheet discharge apparatus which concerns on the 4th Embodiment of this invention. The figure which shows the structure of the side pressure cam provided in the said sheet | seat discharge apparatus. The figure explaining the drive system of the said sheet discharge apparatus. 6 is a timing chart showing driving timing of the sheet discharging apparatus. FIG. 4 is a control block diagram for controlling a sheet discharging operation of the sheet discharging apparatus. 6 is a flowchart for explaining a sheet discharging operation of the sheet discharging apparatus. FIG. 4 is a diagram illustrating a state when a side pressure cam provided in the sheet discharge device is in an initial state. The figure which shows the position of a projection part when the said side pressure follower exists in an initial state. The figure which shows the position of a projection part when the said side pressure follower rotationally moves from the initial state. The figure which shows the state of the said sheet discharge apparatus when the said side pressure follower rotationally moves from the initial state. The figure which shows the other structure of the said sheet | seat discharge apparatus. The figure which shows the structure of the sheet discharge apparatus which concerns on the 5th Embodiment of this invention. FIG. 10 is a perspective view illustrating a configuration of a pair of paper discharge rollers provided in a conventional sheet discharge device. FIG. 5 is a diagram illustrating a state in which a wave shape is formed on a sheet by the conventional discharge roller pair. The figure which calculated | required experimentally the relationship between the noise and the amount of seating in the conventional paper discharge roller pair.

Explanation of symbols

2 discharge roller pair 3 drive shaft 4 drive roller 4a drive roller unit 4b, 4c auxiliary roller unit 5 pressure roller 7 side pressure cam 9 side pressure follower 19 laminated piezoelectric element 51 CPU (calculation processing unit)
56 Position Detection Sensor 100 Image Forming Apparatus 100C Image Forming Unit 117A Fixing Unit 201 Sheet Discharge Device 201A First Discharge Roller Pair 201B Second Discharge Roller Pair 201C Third Discharge Roller Pair 202 First Drive Roller 202a Roller Unit 203 First 1 waist roller 203a waist roller portion 203b flange portion 204 second drive roller 204a roller portion 205 second waist roller 205a waist roller portion 205b flange portion 206 drive roller shaft 207 waist roller shaft 208 drive roller shaft 209 waist Roller shaft 209a Waist roller portion 212 Third waist roller 212a Waist roller portion 212b Flange portion 213 Waist roller shaft 214 Third drive roller 214a Roller portion 215 Drive roller shaft 502 Drive roller 502a Roller portion 503 First waist roller 03a waist with the roller portion 503b flange portion 505 the second waist application rollers 505a waist with the roller portion 505b flange portion S sheet

Claims (11)

A sheet discharge device that discharges a sheet on which an image is formed as a wave shape in a width direction orthogonal to the sheet discharge direction,
A first roller having a first roller shaft and a plurality of roller bodies provided coaxially with the first roller shaft; and a second roller shaft and coaxially provided with the second roller shaft; A second roller having a plurality of roller main bodies in contact with the roller main body, and a plurality of roller pairs for discharging the sheet as a corrugated shape in the sheet discharge direction,
When discharging the sheet, the roller body of the first roller of the pair of rollers disposed on the upstream side in the sheet discharging direction so as to gradually increase the force that forms a wave shape on the sheet applied by the roller pair, and the first roller The number of roller bodies of two rollers is smaller than the number of roller bodies of the first roller and second roller of the pair of rollers arranged on the downstream side in the sheet discharging direction. apparatus. One of the first roller and the second roller of the pair of rollers arranged in the sheet discharge direction is provided with a flange portion having a diameter larger than that of one of the first roller and the second roller. ,
2. The sheet discharge apparatus according to claim 1, wherein a diameter of the flange portion on the upstream side in the sheet discharge direction is smaller than a diameter of the flange portion on the downstream side in the sheet discharge direction. A sheet discharge device that discharges a sheet on which an image is formed as a wave shape in a width direction orthogonal to the sheet discharge direction,
A first roller having a first roller shaft and a plurality of roller bodies provided coaxially with the first roller shaft; and a second roller shaft and coaxially provided with the second roller shaft; A plurality of second rollers having a plurality of roller main bodies in contact with the roller main body, and a roller pair for discharging the sheet as a wave shape,
A plurality of the second rollers are brought into contact with the outer peripheral surface of the first roller;
A flange having a diameter larger than that of the roller body of the second roller, so as to gradually increase the force of corrugating the sheet applied to the sheet by the first roller and the second roller. Each has a part,
The sheet discharging apparatus according to claim 1, wherein a diameter of the flange portion on the upstream side in the sheet discharging direction is smaller than a diameter of the flange portion on the downstream side in the sheet discharging direction. A sheet discharge device that discharges a sheet on which an image is formed as a wave shape in a width direction orthogonal to the sheet discharge direction,
A first roller having a first roller shaft and a plurality of roller bodies provided coaxially with the first roller shaft; and a second roller shaft and coaxially provided with the second roller shaft; A second roller having a plurality of roller bodies in contact with the roller body, and a roller pair for discharging the sheet as a wave shape,
An auxiliary roller part provided at both ends of one of the first roller and the second roller and having a radial length that changes due to elastic deformation;
A pressing portion that presses in the axial direction so as to elastically deform the auxiliary roller portion, and
The auxiliary roller portion is gradually pressed by the pressing portion so that the radial length of the auxiliary roller portion is longer than the radial length of the roller body, and the force applied to the sheet to make the sheet corrugated A sheet discharging apparatus characterized by being gradually increased.   The sheet discharging apparatus according to claim 4, wherein the length of the auxiliary roller portion in the radial direction is the same as or shorter than the length of the roller body in the radial direction until the auxiliary roller portion is pressed by the pressing portion. A sheet conveying unit configured to convey a sheet to a contact portion between the first roller and the second roller;
The said pressing part is comprised by the cam follower rotated in response to the sheet conveyance operation | movement by the said sheet conveyance part, and the cam pressed by the said cam follower and pressing the said auxiliary | assistant roller part. The sheet discharging apparatus according to 4 or 5. The pressing unit, when the driving voltage is applied, the sheet discharging device according to claim 4 or 5, wherein it is a piezoelectric element for pressing the auxiliary roller portion extends in the axial direction. Provided with a discriminator that discriminates the physical property value of the sheet,
8. The sheet discharge apparatus according to claim 7, wherein the amount of elastic deformation of the auxiliary roller unit is controlled by controlling the magnitude of the driving voltage in accordance with output information of the determination unit. A sheet position detection unit that is provided upstream of the contact portion between the first roller and the second roller in the sheet discharge direction, and detects the position of the sheet;
The sheet discharging apparatus according to claim 4, wherein the pressing unit is operated based on a signal from the sheet position detection unit.   The sheet according to any one of claims 4 to 9, wherein an elastic deformation amount of the auxiliary roller portion is controlled by changing at least one of a thickness and a material hardness of the auxiliary roller portion. Discharging device.   An image forming apparatus comprising: an image forming unit; and a sheet discharging device according to any one of claims 1 to 10, which discharges a sheet on which an image is formed by the image forming unit.

Images