Curl correcting apparatus and image forming apparatus

A curl correcting apparatus includes rollers, a motor, and a clutch portion. The rollers are curl correction-use rollers which are arranged in parallel to each other in a pressure-contact state and which are different in hardness. The motor is a motor capable of rotating in forward and reverse directions relative to a correction-amount adjusting portion that changes and adjusts a distance to the rollers as a result of an eccentric cam that integrally rotates in accordance with a rotation amount of a rotation shaft, pressing against the rollers. The clutch portion transmits a rotary driving force of the motor to the rollers during the forward rotation and to a rotation shaft during the reverse rotation.

CROSS REFERENCE OF RELATED APPLICATION

The disclosures of Japanese patent application No. 2015-142029 filed on Jul. 16, 2015 and Japanese patent application No. 2016-102235 filed on May 23, 2016 are incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a curl correcting apparatus that corrects a curl generated in a recording paper and relates also to an image forming apparatus.

Description of the Related Art

It is known that as a result of toner being contracted after a fixation, a recording paper fixed in a heated and pressured state is curled and distorted. The curl causes a paper jam in a paper transporting path, and a post-processing portion that processes the recording paper in a stacking state may not be capable of performing a good post-process. Further, it is known that the curling differs in amount also depending on a material and the like of the recording paper.

One example of a related art is disclosed in Japanese patent application laying-open No. 2010-132368 [B65H 29/70] (Literature 1) laid-open on Jun. 17, 2010. A curl correcting apparatus disclosed in this Literature 1 corrects curl and is provided with a curl-correction-amount adjusting mechanism. More specifically, the curl correcting apparatus is arranged along a paper transporting path from an image forming apparatus to a post-processing apparatus, and has a roller made of sponge and a roller made of metal facing each other in a pressure-contact state. Further, the curl-correction-amount adjusting mechanism causes a dedicated curl-correction-amount adjusting motor to drive to thereby move the roller made of sponge in a pressure-contact direction toward and away from the roller made of metal, whereby a curl correction amount is adjusted.

In the curl correcting apparatus disclosed in this Literature 1, one of the roller made of sponge and the roller made of metal arranged, as a curl correction-use, to face each other is driven to be rotated by a recording paper transportation-use motor so that a recording paper is also transported. Therefore, the curl correcting apparatus is provided with the recording paper transportation-use motor and the curl-correction-amount adjusting motor, and as a result, the apparatus becomes large in size and a cost increases.

SUMMARY OF THE INVENTION

The present invention has been achieved in view of the foregoing, and an object thereof is to provide a curl correcting apparatus and an image forming apparatus with which it is possible to enable, with a single rotary driving portion, transportation of recording paper and adjustment of a curl correction amount.

The present invention includes: a curl correcting portion that has a first roller and a second roller which are arranged in parallel to each other in a pressure-contact state and which are different in hardness; an adjusting portion that includes an adjustment rotation shaft having an abutting portion and that adjusts a distance to the first roller as a result of the abutting portion pressing against, in accordance with a rotation amount of the adjustment rotation shaft, the second roller; a rotary driving portion capable of rotating in forward and reverse directions; and a clutch portion that transmits a rotary driving force of the rotary driving portion to the first roller during the forward rotation and to the adjustment rotation shaft during the reverse rotation.

It is possible to appropriately correct a curl generated in a recording paper by adjusting a setting of a curl correction amount. The curl amount differs depending on a material or a type of the recording paper, and thus, it is preferable to adjust the curl correction amount in accordance with the curl amount. The curl is corrected by passing the recording paper between a pair of pressure-contacted rollers different in hardness, and further, the curl correction amount is made adjustable by adjusting the pressure-contact state of the pair of rollers, that is, a distance between rotation shafts of the pair of rollers. It is noted that a distance between the pair of rollers may be adjusted. This results in an operation where the transportation of the recording paper and the adjustment operation of the curl correction amount are performed with a single rotary driving portion. When adjusting a relative distance between the rotation shaft of the second roller and the rotation shaft of the first roller, out of the pair of the first roller and the second roller, a driving force of the rotary driving portion is transmitted to the first roller, by the clutch portion, to be driven during a forward rotation, that is, the relative distance remains unchanged, resulting in an exclusive transported state, and on the other hand, the driving force of the rotary driving portion is transmitted to the adjustment rotation shaft during a reverse rotation, and the relative distance is changed and adjusted. Therefore, with a single rotary driving portion, the transportation of the recording paper, the curl correcting operation, and the adjustment operation of the curl correction amount are made possible, and as a result, it is possible to achieve space-saving and also possible to provide a reasonably priced apparatus.

Further, it is characterized in that the abutting portion of the adjusting portion includes an eccentric cam. According to the configuration, it is possible to perform adjustment by rotating the adjustment rotation shaft.

Further, the second roller is supported by a transportation guiding portion, and it is characterized in that the adjusting portion adjusts a distance to the second roller via the transportation guiding portion. According to the configuration, integration with a transporting guide enables ensuring of a constant smooth transportation even when a relative position of the first roller and the second roller is changed while reducing a change as much as possible in transportation path of the recording paper.

Further, it is characterized in that the hardness of the first roller is lower than the hardness of the second roller. According to the configuration, a nip portion is provided between the pair of rollers, and therefore, when the distance between the rotation shafts of the pair of rollers is adjusted, it is possible to adjust a nip pressure, that is, a correcting pressure.

Further, the adjustment rotation shaft is provided with a detection piece that rotates together with the adjustment rotation shaft, and it is characterized in further including: an optical sensor; and a rotation amount control means that detects, on the basis of output of the optical sensor, whether there is at least the detection piece to control a rotation amount of the adjustment rotation shaft. The rotation amount of the adjustment rotation shaft is controlled by using the optical sensor, and thus, it is possible with a simple configuration to appropriately adjust the correcting pressure in accordance with a thickness and the like of the recording paper.

Further, the clutch portion is provided with a first one-way clutch and a second one-way clutch, and it is characterized in that in the first one-way clutch, a first input shaft is linked to the rotary driving portion, a first output shaft is linked to the first roller, in the second one-way clutch, a second input shaft is linked to the first input shaft, and a second output shaft is linked to the adjustment rotation shaft. According to the configuration, by the two one-way clutches, it is possible to adjust the curl correction amount in a light load state where the first roller and another transporting roller for transporting the recording paper are stopped from rotating.

Further, the clutch portion includes a one-way clutch, and it is characterized in that in the one-way clutch, an input shaft is linked to the rotary driving portion and an output shaft is linked to the adjustment rotation shaft. Even when one direction clutch is used, it is possible with a single rotary driving portion to enable the transportation of the recording paper, the curl correcting operation, and the adjustment operation of the curl correction amount.

Further, an image forming apparatus according to the present invention is provided with the curl correcting apparatus, and a drive controlling portion that rotates forwardly the rotary driving portion during transportation of a recording paper and rotates reversely the rotary driving portion during curl correction-amount adjustment. According to the configuration, it is possible to provide an image forming apparatus capable of adjusting the curl correction amount.

The above described objects and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS

As shown inFIG. 1, in a main boy upper portion of an image forming apparatus1, a scanner device2that reads an image of an original to generate image data is mounted, and in a main body thereof, there are provided: an image forming unit3that executes an image forming process on a recording paper; a paper feeding unit4that feeds the recording paper to the image forming unit3; a relay transporting unit5that guides the recording paper to a post-processing unit6, while correcting a curl of the recording paper that passes through the image forming unit3; and the post-processing unit6that executes a post process on the recording paper on which the image forming process is performed. Further, the image forming apparatus1is provided with a paper transporting path7configured by: a transporting guide and a transporting roller group that transport the recording paper from the paper feeding unit4to the relay transporting unit5.

The image forming unit3is provided with a photosensitive drum31rotating at a constant speed, and around the photosensitive drum31, from a rotation-direction upstream side, an exposure position32, a developing portion33, a transfer portion34, and the like are arranged. The image forming unit3is provided with a fixing portion35at a paper-transporting-direction downstream side of the transfer portion34. The fixing portion35is provided with a heating roller and a pressuring roller that hold the recording paper therebetween, and heats and fuses a toner image transferred onto the recording paper to be fixed onto the recording paper. At the paper-transporting-direction downstream side of the fixing portion35, a transportation roller71that transports the recording paper to the relay transporting unit5is provided.

The paper feeding unit4is provided with a paper-feeding cassette, which preferably is plural, which accommodates a recording paper different in type (such as size, thickness, and basis weight). Each paper-feeding cassette is arranged to correspond to a paper-feeding mechanism that feeds the recording paper, one by one, to the paper transporting path7.

The relay transporting unit5performs a curl correcting process on an input recording paper which is then output to the post-processing unit6, and functions as a curl correcting apparatus. A configuration of the relay transporting unit (curl correcting apparatus)5will be described later.

The post-processing unit6is provided with a switching portion61that switches a transporting direction of the recording paper input from the relay transporting unit5, a staple tray62, which is an example of the post-process, and a paper-receiving tray63and a paper-receiving tray64. The post-processing unit6discharges the recording paper directly to the paper-receiving tray63, or guides the recording paper to the staple tray62, in response to the switching portion61. The recording paper on which a staple process is performed is discharged to the paper-receiving tray64. It is noted that a sort processing portion, a punch processing portion, and the like, which are well known as the post-processing portion, may be included.

Next, by usingFIG. 2toFIG. 10, the curl correcting apparatus5will be described. The curl correcting apparatus5includes, inside a main body5A having both side surfaces in a widthwise direction, two lower-surface-side transporting guides501,502(seeFIG. 2) arranged side by side from an upstream side (the right inFIG. 2) in the paper-transporting direction toward a downstream side (the left inFIG. 2). It is noted that upper-surface-side transporting guides facing the lower-surface-side transporting guides501,502are omitted fromFIG. 2for the sake of an illustration of an internal structure. In the lower-surface-side transporting guides501,502, a required number of transporting rollers511,512are each disposed, along a transporting direction, symmetrically in a direction orthogonal to a paper transporting direction (hereinafter, widthwise direction), where the transporting rollers511,512are each partially exposed from a top surface. It is noted that as partially seen inFIG. 3, in an upper-surface-side transporting guide facing the transporting rollers511,512, a driven roller is arranged. Further, inFIG. 1, the paper transporting direction in the curl correcting apparatus5is a direction from right to left, and the widthwise direction is a direction vertical to the sheet ofFIG. 1.

At a substantially center position between the upstream side and the downstream side, a roller53and a roller543(seeFIG. 3) for correcting a curl respectively different in hardness are arranged, in a pressure-contact state, in parallel to each other. The roller53is formed of a material of which the surface is relatively easily deformable, for example, sponge or the like, and the roller543is formed of a material of which the surface is relatively hard, for example, metal or the like. When the recording paper is pressed against a roller53side of the sponge deformed by pressure contact while passing between the roller53and the roller543, the curl generated after being fixed is corrected. It is noted that as described later, a distance between the roller53and the roller543is set adjustable. Strictly speaking, a distance between a rotation shaft of the roller53and a rotation shaft of the roller543is adjustable. InFIG. 3, it is shown that a roller543′ is in a state of being adjusted to a position closer to the roller53.

The roller543is supported by a guiding member54, as shown inFIG. 4. The guiding member54has side plates541at widthwise both sides, and between the both side plates541, a long guide surface portion542is supported. The roller543is axially supported rotatably by bearings5411of the both side plates541. The recording paper passes at an upper surface side of the roller543along the guide surface portion542to thereby be held in between with the roller53, has the curl corrected, and receives a transporting force.

Further, the guiding member54has a fitting portion5412which is notched into a U-lettered shape and which is axially supported by a swinging shaft540(see alsoFIG. 3) erected on a side wall of the main body5A, and is made capable of swinging around the swinging shaft540. As a result of the swinging, the distance between the rotation shaft of the roller543and the rotation shaft of the roller53is made adjustable. When the distance between the rotation shaft of the roller543and the rotation shaft of the roller53is long, a deformation amount of the roller53made of sponge is small and thus the curl correcting amount (correcting force) is small, and the shorter the distance between the rotation shaft of the roller543and the rotation shaft of the roller53, the larger the deformation amount of the roller53made of sponge, and hence, the curl correcting amount is large. That is, when the distance between the rotation shaft of the roller543and the rotation shaft of the roller53is adjusted, the correcting amount (correcting force) of the curl is adjusted. It is noted that a mode in which the roller543is alone moved may be possible; however, in a mode in which the roller543is swung together with the guiding member54, it is possible to unfailingly guide the recording paper to a held position even in a change in distance between the rotation shaft of the roller543and the rotation shaft of the roller53.

In an appropriate position of the guiding member54, the position being opposite to the fitting portion5412, a pair of abutting portions54aare provided in the widthwise direction in the present embodiment. As described later, when an external force is effected on the abutting portion54a, the swinging around the swinging shaft540is executed.

As shown inFIG. 2,FIG. 3, andFIG. 5, a correcting-amount adjusting portion56that swings the guiding member54is provided near the guiding member54. The correcting-amount adjusting portion56is supported coaxially by a one-way clutch55, as described later, in the present embodiment. The correcting-amount adjusting portion56is provided with: a rotation shaft561that extends in the widthwise direction and that is axially supported at both sides of the main body5A; an eccentric cam562that is fixed to the rotation shaft561and that abuts the abutting portion54a(seeFIG. 5); and a detection piece563that is fixed to the rotation shaft561and that is for detecting a rotation phase, for example, a reference angle position (seeFIG. 2).

In the eccentric cam562, a distance from a rotation center is gradually changed relative to a peripheral direction, for example. In order to detect the reference angle position of the rotation shaft561when being detected by an optical sensor5B (seeFIG. 5,FIG. 7, andFIG. 9) and the like provided at a main body5A side, the detection piece563is fixedly provided to the rotation shaft561.

When the eccentric cam562swings the abutting portion54aby an eccentric distance corresponding to a rotation phase position of the rotation shaft561, in defiance of a biasing force by a spring (not shown) or the like toward a clockwise direction (FIG. 3) around the swinging shaft540, a swinging amount of the guiding member54, that is, a distance between the rotation shaft of the roller543and the rotation shaft of the roller53, is adjusted. Therefore, when the surface of the roller53is deformed, a nip pressure of the nip portion between the roller543and the roller53is changed and the curl correcting amount (correcting pressure) is adjusted. However, in the image forming apparatus1that performs printing on the recording paper having a large thickness, the roller543and the roller53may be arranged to be separated. In such a case, not only the distance of the rotation shaft of the roller543relative to the rotation shaft of the roller53but also a distance toward and away from the roller543relative to the roller53may be adjusted. Therefore, the curl correcting amount may be adjusted by the distance toward and away from the roller543relative to the roller53. When such a configuration is adopted, from a relationship between the reference angle position and the eccentric distance corresponding to the rotation phase position of the eccentric cam562, it is possible to set the curl correcting amount according to a rotation amount from a reference (reference angle position) of the rotation shaft561.

The detection piece563is fixed to a predetermined position of the rotation shaft561and rotates together with the rotation shaft561. Although not easy to see from the drawings, the detection piece563is formed in a substantially rectangular plate shape having a width capable of shielding a sensing portion (light receiving portion) of the optical sensor5B, and a longitudinal direction thereof is a direction extending in a radial direction from a center of the rotation shaft561. In the first embodiment, in the reference angle position of the rotation shaft561, the detection piece563is arranged so that the sensing portion of the optical sensor5B is shielded.

For example, the optical sensor5B is a transmissive optical sensor, and light irradiated from a light emitting portion is received by a light receiving portion. Therefore, the thickness of the detection piece563is set smaller than an interval between the light emitting portion and the light receiving portion. However, when the light receiving portion is shielded by the detection piece563, the light irradiated from the light emitting portion is not received by the light receiving portion. Therefore, by a change in light received by the light receiving portion, output of the optical sensor5B is changed.

It is noted that although a detailed description is omitted, as the optical sensor5B, a reflective optical sensor may also be used. In such a case, when the detection piece563is located at a position corresponding to the light emitting portion and the light receiving portion, reflected light is detected by the light receiving portion, for example.

FIG. 6Ais a cross-sectional view showing one example of an inclination amount of the guiding member54relative to a rotation position of the eccentric cam562when a correcting pressure is minimum, andFIG. 6Bis a cross-sectional view showing one example of the inclination amount of the guiding member54relative to the rotation position of the eccentric cam562when the correcting pressure is maximum. However,FIG. 6AandFIG. 6Bshow a cross-sectional view of a case where the eccentric cam562at a side not shown inFIG. 5is cut in a direction in parallel to the paper transporting direction and vertical to the direction of the rotation shaft561. It is noted that inFIG. 6AandFIG. 6B(same applied toFIG. 7A, andFIG. 7B), the rotation shaft of the roller53is shown in hatching and the hatching in a sponge portion is omitted.

As shown inFIG. 6A, when the correcting force is minimum, a distance from a center of a rotation of the eccentric cam562(center of the rotation shaft561) to a position at which an outer peripheral surface of the eccentric cam562contacts a convex portion of the abutting portion54ais the shortest. Therefore, an inclination amount (swinging) of the guiding member54relative to a horizontal surface is minimum, and the distance between the rotation shaft of the roller53and the rotation shaft of the roller543is the longest. However, when the correcting force is minimum, the rotation shaft561stops at the reference angle position. However, the convex portion is provided to downwardly protrude toward a lower surface of the abutting portion54a.

On the other hand, as shown inFIG. 6B, when the correcting force is maximum, the distance from the center of a rotation of the eccentric cam562to the position at which the outer peripheral surface of the eccentric cam562contacts the convex portion of the abutting portion54ais the longest. Therefore, the inclination amount of the guiding member54relative to the horizontal surface is maximum, and the distance between the rotation shaft of the roller53and the rotation shaft of the roller543is the shortest.

As shown inFIG. 6AandFIG. 6B, when the main body5A of the curl correcting apparatus5is seen from one side (a nearer side ofFIG. 2), as described later, the rotation shaft561is rotated (moved rotationally) in a counterclockwise direction, and the eccentric cam562is also rotated (moved rotationally) in accordance therewith. In accordance with a distance from the center of the rotation of the eccentric cam562determined at a position at which the rotation (moving rotationally) of the rotation shaft561is stopped, to a position at which the outer peripheral surface of the eccentric cam562contacts the abutting portion54a, the distance between the rotation shaft of the roller53and the rotation shaft of the roller543is determined, and as a result, the correcting pressure is determined.

FIG. 7Ais an illustrated diagram showing one example of a position of the detection piece563relative to a sensing portion of the optical sensor5B when the correcting pressure is minimum, andFIG. 7Bis an illustrated diagram showing one example of the position of the detection piece563relative to the sensing portion of the optical sensor5B when the correcting pressure is maximum. However,FIG. 7AandFIG. 7Bshow a cross-sectional view of a case where the detection piece563is cut in a direction in parallel to the paper transporting direction and vertical to the direction of the rotation shaft561.

As shown inFIG. 7A, when the correcting pressure is minimum, the detection piece563is stopped at a position at which the sensing portion of the optical sensor5B is shielded. Specifically, when the rotation shaft561is rotated (moved rotationally), the rotation shaft561arrives at the reference angle position, and then, the light from the light emitting portion of the optical sensor5B is shielded by the detection piece563. Thereafter, on the basis of output of the optical sensor5B, the rotation of the rotation shaft561is stopped. That is, when the correcting force is set to minimum, the rotation shaft561may be rotated to cause the detection piece563to be stopped at a position at which the light receiving portion of the optical sensor5B is shielded.

On the other hand, when the correcting pressure is maximum, as described above, the rotation shaft561is moved rotationally so that the distance from the center of the rotation of the eccentric cam562to the position at which the outer peripheral surface of the eccentric cam562contacts the convex portion of the abutting portion54ais the longest. At this time, as shown inFIG. 7B, for example, the detection piece563is stopped at a position that overlaps a position at which the outer peripheral surface of the eccentric cam562contacts the abutting portion54a(seeFIG. 6B).

For example, when a rotation angle (rotationally moving amount) of the rotation shaft561when the correcting pressure is maximum and a correcting pressure corresponding to the rotation angle are previously measured from the reference angle position when the correcting pressure is minimum, the rotation amount of the rotation shaft561is controlled, whereby it is possible to adjust linearly or stepwise the correcting pressure (curl correcting amount).

The roller53, the transporting rollers511,512, and the rotation shaft561of the correcting-amount adjusting portion56, which form a transportation system, are rotated and driven by a motor57, which is a single rotation drive source.

FIG. 8is a lateral cross-sectional view showing an adjustment system of the curl correcting apparatus5according to the first embodiment.FIG. 9is a perspective view obtained when the adjustment system of the curl correcting apparatus5according to the first embodiment is seen from an obliquely downward direction.FIG. 10is a simplified view showing the adjustment system of the curl correcting apparatus5according to the first embodiment. It is noted thatFIG. 10shows a case where the main body5A of the curl correcting apparatus5is seen from one side to the other side (the farther side ofFIG. 2).

InFIG. 8toFIG. 10, among the motor57, the roller53, the transporting rollers511,512, and the rotation shaft561, a one-way clutch mechanism is interposed. In the first embodiment, as the one-way clutch mechanism, two one-way clutches52,55are provided. The one-way clutches52,55each include a respectively concentric input shaft and output shaft, and as well known, when the input shaft is rotated forwardly, the output shaft is rotated together therewith, and on the other hand, when the input shaft is rotated reversely, the output shaft is not rotated (becomes static). Further, although not essential, a relay roller portion58is interposed. As understood fromFIG. 2andFIG. 8, the motor57, the one-way clutches52,55, and the relay roller portion58are supported by a side wall at the other side (the farther side ofFIG. 2) of main body5A.

The one-way clutch52includes an input shaft521and an output shaft522, and as shown inFIG. 9andFIG. 10, the input shaft521is linked via a belt571to a roller fixed to the rotation shaft of the motor57, and abuts a first roller581of the relay roller portion58to enable integrated rotation. It is noted that the motor57is omitted inFIG. 9. This applies toFIG. 11described later.

Further, the output shaft522of the one-way clutch52is integrally joined coaxially with the curl correction-use roller53, and abuts a second roller582of the relay roller portion58. It is noted that inFIG. 10, in the one-way clutch52, when the input shaft521is rotated in a clockwise direction (hereinafter, CW direction), the output shaft522is rotated together therewith, and when the input shaft521is rotated in a counterclockwise direction (hereinafter, CCW direction), the output shaft522is not rotated together therewith but becomes static. Further, inFIG. 9, when the second roller582(as well as the one-way clutch55) is indicated by a dotted line, a roller arranged at a rear side of the second roller582inFIG. 9is transmitted so as to be seen.

The relay roller portion58includes the first roller581, the second roller582, a third roller583, and a fourth roller583′ which are respectively coaxial, and the first roller581and the third roller583are rotated integrally and separately the second roller582and the fourth roller583′ are rotated integrally. As well understood fromFIG. 9, the first roller581, the second roller582, the third roller583, and the fourth roller583′ are coaxially arranged side by side in the widthwise direction. The third roller583is arranged at an end of the other side in the widthwise direction of the main body5A, and the first roller581formed integrally (joined integrally) with the third roller583is arranged inside the third roller583. Further, inside the first roller581, the fourth roller583′ and the second roller582are arranged in this order. Although difficult to see in the drawing, the third roller583and the first roller581are integrally joined, and the fourth roller583′ and the second roller582are integrally joined.

As shown inFIG. 9andFIG. 10, the third roller583of the relay roller portion58is linked via a belt591to a roller5110fixed to the rotation shaft of a transporting roller511, the fourth roller583′ of the relay roller portion58is linked via a belt592to a roller5120fixed to the rotation shaft of a transporting roller512arranged downstream of the paper transporting direction, and the roller5120is linked via a belt593to a roller5122fixed to the rotation shaft of another transporting roller512arranged further downstream of the paper transporting direction. Further, the first roller581of the relay roller portion58abuts the one-way clutch55.

The one-way clutch55includes a respectively coaxial input shaft551and output shaft552, and the input shaft551abuts the first roller581to enable integrated rotation and the output shaft552is integrally joined coaxially with the rotation shaft561of the correcting-amount adjusting portion56. It is noted that inFIG. 10, in the one-way clutch55, when the input shaft551is rotated in the CW direction, the output shaft552is not rotated together therewith, and when the input shaft551is rotated in the CCW direction, the output shaft552is rotated together therewith.

In the above configuration, now, an operation of each portion during recording paper transportation and during curl correcting amount adjustment will be described with reference toFIG. 9andFIG. 10.

(1) During Recording Paper Transportation

As shown inFIG. 10A, when the motor57is rotated in the CW direction (forward direction), the input shaft521of the one-way clutch52is rotated in the CW direction, and the output shaft522also is rotated in the CW direction together therewith. Accordingly, when the first roller581and the third roller583are rotated, the upstream roller5110(transporting roller511) is rotated in the paper transporting direction (CCW direction) as indicated by an arrow. Further, as understood also with reference toFIG. 9, when the output shaft522also is rotated together therewith, the roller53also is rotated in the CW direction, and as a result, the second roller582and the fourth roller583′ are rotated in the paper transporting direction (CCW direction). Further, when the fourth roller583′ is rotated, the rollers5120,5122(transporting rollers512,512) are rotated in the paper transporting direction (CCW direction).

Further, when the rotation of the first roller581allows the input shaft551of the one-way clutch55to rotate in the CW direction; however, as indicated by a dotted arrow inFIG. 10A, the output shaft552is not rotated together therewith, and thus, the rotation shaft561of the correcting-amount adjusting portion56remains static.

Thus, when the motor57is rotated in the CW direction, the roller53and the transporting rollers511,512are rotated, and at the same time, the rotation shaft561is in a static state and the recording paper is transported only.

(2) During Curl Correcting Amount Adjustment

As shown inFIG. 10B, when the motor57is rotated in the CCW direction (reverse direction), the input shaft521of the one-way clutch52is rotated in the CCW direction, and at the same time, the output shaft522becomes static. Therefore, the roller53integrated with the output shaft522remains static. Further, as seen also with reference toFIG. 9, when the first roller581and the third roller583are rotated, the upstream roller5110(transporting roller511) is rotated in the CW direction, and at the same time, the output shaft522is static and thus the second roller582and the fourth roller583′ are static, and the downstream rollers5120,5122(transporting rollers512,512) are static.

Further, when the rotation of the first roller581allows the input shaft551of the one-way clutch55to rotate in the CCW direction, as a result, as indicated by an arrow inFIG. 10B, the output shaft552is rotated together therewith in the CCW direction, and thus, the rotation shaft561of the correcting-amount adjusting portion56is rotated. That is, when the rotation shaft561is rotated and the rotation amount is controlled, as described above, the distance between the rotation shaft of the roller543and the rotation amount of the roller53is adjusted to thereby appropriately adjust the curl correcting amount.

Thus, when the motor57is rotated in the CCW direction, the roller53and the transporting roller512are static (it is noted that the transporting roller511is rotated in the CW direction) and the rotation shaft561is in a state of being rotated, and as a result, it is possible to adjust the curl correcting amount by the drive amount control of the motor57. In addition, at this time, when the driving force transmission to the roller53and the transporting roller512is blocked, a load to the motor57is thereby alleviated.

The image forming apparatus1according to a second embodiment is the same as the image forming apparatus1according to the first embodiment except for some difference in configuration and operation of the curl correcting apparatus5, and thus, a different content from the first embodiment will be described and the overlapping content will be omitted or briefly described.

FIG. 11is a perspective view obtained when an adjustment system of the curl correcting apparatus5according to the second embodiment is seen from an obliquely downward direction.FIG. 12is a simplified view showing the adjustment system of the curl correcting apparatus5according to the second embodiment.

FIG. 11andFIG. 12show a configuration of the curl correcting apparatus5according to the second embodiment, and are figures corresponding toFIG. 9andFIG. 10in the first embodiment. In the first embodiment, the two one-way clutches52,55are adopted; however, even when the one-way clutch52only is used, a similar transporting operation and adjusting operation are possible. InFIG. 11andFIG. 12, the same portions as those inFIG. 9andFIG. 10are assigned the same reference numerals.

InFIG. 11andFIG. 12, a difference fromFIG. 9andFIG. 10includes a feature that the third roller583is made longer in the widthwise direction (axial line direction) and the roller5120is linked via the belt592with the third roller583. Further, the fourth roller583′ and the one-way clutch55are not adopted. Further, the roller53is integrally joined coaxially with the input shaft521, and the output shaft522is extended to the other side in the widthwise direction of the main body A. Although not easily understood from the figure, the one-way clutch52is arranged in a reverse direction as compared to a case shown inFIG. 9andFIG. 10. In a manner to abut the output shaft522, the second roller582is arranged at the other side, relative to the third roller583, in the widthwise direction of the main body A. Therefore, in the second embodiment, between the second roller582and the first roller581, the third roller583is arranged. However, a feature that the first roller581and the third roller583are joined integrally is the same as in the first embodiment. Further, the rotation shaft561of the correcting-amount adjusting portion56directly abuts the second roller582.

In the above configuration, now, an operation of each portion during the recording paper transportation and during the curl correcting amount adjustment will be described with reference toFIG. 12.

(1) During Recording Paper Transportation

As shown inFIG. 12A, when the motor57is rotated in the CW direction (forward direction), the input shaft521of the one-way clutch52is rotated in the CW direction, and at the same time, the output shaft522becomes static. Therefore, the roller53integrated with the input shaft521is rotated together therewith. Further, as understood also with reference toFIG. 11, when the input shaft521is rotated to allow the first roller581and the third roller583to rotate in the CCW direction, the rollers5110,5120, and5122(transporting rollers511,512, and512) also are rotated in the CCW direction. On the other hand, as indicated by a dotted arrow inFIG. 12A, the output shaft522is static, and thus, the second roller582is static and the rotation shaft561of the correcting-amount adjusting portion56remains static.

Thus, when the motor57is rotated in the CW direction, the roller53and the transporting rollers511,512are rotated, and at the same time, the rotation shaft561is in a static state and the recording paper is transported only.

(2) During Curl Correcting Amount Adjustment

As shown inFIG. 12B, when the motor57is rotated in the CCW direction (reverse direction), the input shaft521of the one-way clutch52is rotated in the CCW direction, and the output shaft522also is rotated in the CCW direction together therewith. Therefore, the roller53integrated with the input shaft521is rotated together therewith. Further, as understood also with reference toFIG. 11, when the input shaft521is rotated to allow the first roller581and the third roller583to rotate in the CW direction, the rollers5110,5120, and5122(transporting rollers511,512, and512) are rotated in the CW direction, as indicated by an arrow. Further, when the output shaft522is also rotated together therewith, the second roller582is rotated in the CW direction and the rotation shaft561of the correcting-amount adjusting portion56is rotated in the CCW direction.

That is, when the rotation shaft561is rotated and the rotation amount is controlled, as described above, the distance between the rotation shaft of the roller543and the rotation amount of the roller53is adjusted to thereby appropriately adjust the curl correcting amount.

Thus, when the motor57is rotated in the CCW direction, the roller53and the transporting rollers511,512are rotated in the CW direction, and even in this state, the rotation shaft561is in a state of being rotated, and as a result, it is possible to adjust the curl correcting amount by the drive amount control of the motor57.

In a third embodiment, an example of an electric configuration to realize adjustment of the curl correcting amount described in the first embodiment and the second embodiment will be shown.

A controlling portion100is to control an operation of the image forming apparatus1, and is provided at a predetermined position within a housing of the image forming apparatus1. The controlling portion100is provided with a CPU, and configured by a microcomputer or the like. As shown inFIG. 13, the controlling portion100is connected to an operating portion80, such as a touch panel, capable of receiving input from outside, the image forming unit3, the motor57of the relay transporting unit5, the optical sensor5B, the post-processing unit6, and a memory portion110, for example. The memory portion110is provided with an area which stores a control program (including a program of an adjusting process of the curl correcting amount) executed by the controlling portion100, and a work area.

As a result of causing the CPU to execute the control program, the controlling portion100functions at least as a recording-paper selection processing portion101, a print processing portion102, and a curl-correcting-amount adjusting portion103. The recording-paper selection processing portion101accepts, via the touch panel or the like, a print command, and a designation of a size and a type (such as thickness and basis weight) of the recording paper, and executes a process of selecting a corresponding paper-feeding cassette. After accepting the print command, the print processing portion102operates the image forming unit3or the like to print a predetermined image on the recording paper. At this time, the motor57is rotated in the CW direction to perform the curl correcting process while the recording paper is transported.

When a type of the recording paper is set by the recording-paper selection processing portion101, the curl-correcting-amount adjusting portion103executes, in response to the print command, the adjusting process of the curl correcting amount corresponding to a category of the selected recording paper, before a first piece of sheet is printed. It is noted that the memory portion110stores therein a table showing a relationship between the category of the recording paper and the rotation amount in accordance with the curl correcting amount (rotation angle relative to the reference angle position). More specifically, the curl-correcting-amount adjusting portion103outputs, on the basis of a detection signal of the optical sensor5B, a rotation drive signal for rotating the motor57in the CCW direction by the rotation amount by which the rotation shaft561is moved to a predetermined angle position. It is possible to control the rotation drive signal by a drive pulse number and/or a drive time period depending on the type of the motor57.

Further, in the first embodiment, the upstream transporting roller511(roller5110) is rotated in both the CW and CCW directions; however, may be static during the curl correcting amount adjustment, similarly to the transporting roller512(rollers5120,5122).

Further, in the first embodiment, the eccentric cam562provided in the rotation shaft561is used for adjusting the curl correcting amount; however, instead of the eccentric cam562, an abutting portion may be erected in the rotation shaft561, and in accordance with the rotation phase position of the rotation shaft561, the abutting portion may press against the abutting portion54aof the guiding member54to thereby rotate the guiding member54around the swinging shaft540.

Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims. Further, it is intended that the scope of the present invention includes meanings equivalent to the scope of claims and all the changes within the scope thereof.