SKEWED SHEET CORRECTING DEVICE AND IMAGE FORMING APPARATUS

Abstract

A skewed sheet correcting device includes: first and second shutter members which move to a first position in which the first and second shutter members are pushed to be movable by a leading edge of a sheet, a second position which is disposed further downstream of the sheet conveyance direction than the first position to latch the leading edge of the sheet, and a third position which allows the sheet to pass; and a movement regulating member which, when one of the shutter members does not move to the second position, regulates the other shutter member in the second position, and, when both the first and second shutter members move to the second position, allows the first and second shutter members to move to the third position.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a skewed sheet correcting device that corrects a skew of a sheet in an image forming apparatus and an image forming apparatus including the same.

2. Description of the Related Art

Generally, a position where an image is recorded with respect to a position of a sheet (hereinafter, referred to as “recording accuracy”) is an important element for an image quality in the image forming apparatus. Therefore, in an image forming apparatus of a related art, various skewed sheet correcting devices are provided in order to improve the recording accuracy.

For example, a skewed sheet correcting device that allows a leading edge of a sheet which is conveyed by a pair of conveying rollers to abut on a shutter member so as to be latched with the shutter member, rotates the shutter member to be retracted when the sheet forms a predetermined loop, and allows the sheet to pass through the shutter member is suggested (U.S. Pat. No. 6,011,948).

However, in the skewed sheet correcting device of the related art described above, generally the shutter member is urged by a urging portion such as a spring in advance and a body of the sheet that forms a predetermined loop is affected by the urging force of the urging portion to push the shutter member so as to be retracted.

However, in order to allow a sheet having a lower rigidity such as a thin sheet as compared with a sheet having a higher rigidity such as a thick sheet to pass through the shutter member, it is required to set the urging force of the shutter member to be low. In this case, the sheet having a higher rigidity such as a thick sheet undesirably passes through the shutter member without forming a sufficient loop and thus the skew feeding of the sheet is not appropriately corrected.

In order to solve the above-mentioned problems, a configuration in which the shutter member is retracted under the condition where a detector that detects a leading edge of a sheet is provided and the skew feeding is appropriately corrected is suggested (Japanese Patent Laid-Open No. 9-86726). However, when the detector that detects the leading edge of the sheet is provided, the number of components is increased, leading to a large size and a high cost of the device. Further, Japanese Patent Laid-Open No. 2008-120484 discloses a device including a first gate and a second gate where if the second gate is pushed by the leading edge of a sheet to be conveyed so as to rotate to a correction position, a rotation inhibition plate moves so as to allow the first gate to be rotatable. However, this configuration may not correct the skew feeding of a sheet in which an angle at the second gate side between two angles at the leading edge of the sheet is led.

SUMMARY OF THE INVENTION

It is desirable to provide a skewed sheet correcting device that is capable of correcting the skew feeding regardless of the rigidity of a sheet without increasing the size and the cost.

A skewed sheet correcting device according to the present invention includes: a conveying portion which conveys a sheet; first and second shutter members which are arranged along a width direction perpendicular to the sheet conveyance direction and disposed downstream of the conveying portion in the sheet conveyance direction, wherein the first and second shutter members move to a first position in which the shutter members are pushed to be movable by a leading edge of the sheet which is conveyed by the conveying portion, a second position which is disposed further downstream than the first position in the sheet conveyance direction to latch the leading edge of the sheet, and a third position which allows the sheet to pass; and a movement regulating portion which, when the first shutter member does not move to the second position, regulates the second shutter member that has moved in the second position in the second position, when the second shutter member does not move to the second position, regulates the first shutter member which has moved in the second position in the second position, and, when both the first shutter member and the second shutter member move to the second position, allows the first and second shutter members to move to the third position.

According to the present invention, it is possible to surely correct the skew feeding of a sheet.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an entire skewed sheet correcting device according to a first embodiment.

FIG. 2 is a cross-sectional diagram illustrating a state when a shutter member of the skewed sheet correcting device according to the first embodiment has a first position.

FIG. 3 is a cross-sectional diagram illustrating a state when the shutter member of the skewed sheet correcting device according to the first embodiment has a second position.

FIG. 4 is a cross-sectional diagram illustrating a state when the shutter member of the skewed sheet correcting device according to the first embodiment has a third position.

FIG. 5A is a plan view illustrating the state when the shutter member of the skewed sheet correcting device according to the first embodiment has the first position and FIG. 5B is a plan view illustrating a sheet state when the shutter member of the skewed sheet correcting device according to the first embodiment has the second position.

FIG. 6 is a plan view illustrating the state when the shutter member of the skewed sheet correcting device according to the first embodiment has the first position.

FIG. 7 is a plan view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment has the second position.

FIG. 8 is a perspective view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment has the third position.

FIG. 9A is a perspective view illustrating a rotational position when the shutter member of the first embodiment has the first position or the second position and FIG. 9B is a perspective view illustrating a rotational position when the shutter member of the first embodiment has the third position.

FIG. 10 is a plan view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment has the third position.

FIG. 11 is a perspective view illustrating a shape of a lever member of the skewed sheet correcting device according to the first embodiment.

FIG. 12A is a plan view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment start to rotate first and FIG. 12B is a plan view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment start to rotate first.

FIG. 13A is a side view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment has the second position and FIG. 13B is a side view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the first embodiment has the third position.

FIG. 14A is a side view illustrating a direction of the urging force by a torsion coil spring when the shutter member of the skewed sheet correcting device according to the first embodiment has the third position and FIG. 14B is a side view illustrating a direction of the urging force by a torsion coil spring when the shutter member of the skewed sheet correcting device according to the first embodiment has the first position.

FIG. 15 is a cross-sectional view illustrating an entire configuration of a skewed sheet correcting device according to the present invention and an image forming apparatus including the same.

FIG. 16 is a plan view illustrating a configuration of the skewed sheet correcting device according to the first embodiment.

FIG. 17 is a perspective view illustrating a configuration of the skewed sheet correcting device according to a second embodiment.

FIG. 18 is a plan view illustrating a state of a main part when a shutter member of the skewed sheet correcting device according to the second embodiment has a first position.

FIG. 19 is a cross-sectional view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the second embodiment has the first position.

FIG. 20 is a perspective view illustrating a configuration of the main part of the skewed sheet correcting device according to the second embodiment.

FIG. 21 is a plan view illustrating a state of the main part when the shutter member of the skewed sheet correcting device according to the second embodiment rotates first.

FIG. 22 is a plan view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the second embodiment has a second position.

FIG. 23 is a perspective view illustrating a state of a main part when the shutter member of the skewed sheet correcting device according to the second embodiment has a third position.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, with reference to accompanying drawings, exemplary embodiments of the present invention will be illustratively described in detail. A size, a material, a shape, or a relative arrangement of components described in the following embodiments may be appropriately varied depending on the configuration of an apparatus to which the present invention is applied or various conditions. Therefore, if not specifically described, a scope of the present invention is not limited thereto.

First Embodiment

First, an entire configuration of a skewed sheet correcting device according to a first embodiment and an image forming apparatus including the same will be described with reference to FIG. 15.

A sheet 4 which is accommodated in a feeding unit U and formed of a paper or a synthetic resin is supplied by a feeding roller 18 and then divided by a dividing portion (not shown) one by one to be fed.

The sheet 4 which is fed by the feeding roller 18 is conveyed by a pair of conveying rollers 19 and then sent to a skewed sheet correcting device R disposed further downstream of a sheet conveyance direction (hereinafter, simply referred to as “downstream”). The skew feeding of the sheet 4 is corrected by the skewed sheet correcting device R and then the sheet is conveyed to a photosensitive drum 23 as an image bearing member (electrophotographic photosensitive member) that forms an image forming portion. Further, in the downstream in the vicinity of the skewed sheet correcting device R, and in the further upstream of the sheet conveyance direction compared to the photosensitive drum 23 (hereinafter, simply referred to as “upstream”), a sensor 20 which serves as a sheet detector is disposed to detect the passage of the sheet 4.

In the meantime, a surface of the photosensitive drum 23 is uniformly charged by a charger. A laser scanner 24 controlled by the control unit 25 scans laser light on the photosensitive drum 23 in accordance with image information to form a latent image. A toner is supplied onto the photosensitive drum 23 on which the latent image is formed from a development device to form a toner image. A cleaning device that cleans the photosensitive drum 23, a charger, the development device, and a cleaning portion that cleans the photosensitive drum after being transferred which serve as a processer which operates therefor are provided in a process cartridge 22 which serves as an image forming portion. The process cartridge 22 is detachably attachable to the image forming apparatus.

At the time when the sensor 20 detects the sheet 4, the laser scanner 24 forms a latent image on a surface of the photosensitive drum 23 to form the toner image on the surface of the photosensitive drum 23 by a series of process operations of the process cartridge 22.

The sheet 4 is conveyed between the photosensitive drum 23 and the transfer charger 21 in synchronization with the rotation of the photosensitive drum 23 and the toner image which is formed on the photosensitive drum 23 is transferred on the sheet 4 by the transfer charger 21.

Here, as illustrated in FIG. 1, the skewed sheet correcting device R includes a pair of registration rollers 8 and 10 and the rotational axis thereof is disposed so as to be parallel to the rotational axis direction of the photosensitive drum 23. For example, as illustrated in FIG. 16, when the sheet 4 which is conveyed by the pair of conveying rollers 19 and a pair of conveying rollers 16 is obliquely fed to the pair of registration rollers 8 and 10, the skew feeding is corrected by the operation of the skewed sheet correcting device R. The sheet 4 on which skew feeding is corrected is conveyed so as to arrive on the image forming portion to transfer the image thereon.

The sheet 4 on which the image is transferred is conveyed to a fixing unit 28 and heated and pressurized by the fixing unit 28 so that the toner image is fixed on the sheet 4, and then discharged to the outside of the device by a pair of discharging rollers 26 and 27.

Next, a mechanism of the skew feeding correction by the skewed sheet correcting device according to this embodiment will be described. FIG. 1 is a perspective view illustrating an entire sheet conveying apparatus including a skewed sheet correcting device according to this embodiment and FIG. 2 is a cross-sectional diagram thereof.

In FIG. 1, the sheet 4 is conveyed by the pair of conveying rollers 16 as a first conveying portion and approaches the vicinity of the pair of registration rollers 8 and 10 as a second conveying portion. One of the pair of registration rollers 8 and 10 is a driven registration roller 8 which is provided at a driven registration roller shaft 7 and the other one is a drive registration roller 10 which is provided at a drive registration roller shaft 9. The pair of registration rollers 8 and 10 is disposed further downstream of the sheet conveyance direction than the pair of conveying rollers 16.

In the vicinity of the pair of registration rollers 8 and 10, a plurality of shutter members 1a and 1b is provided in order to correct the skew feeding of the sheet. The shutter members 1a and 1b are provided in an axial direction (a width direction perpendicular to the sheet conveyance direction). The plurality of shutter members 1a and 1b is disposed further downstream of the sheet conveyance direction than the pair of conveying rollers 16 and further upstream of the sheet conveyance direction than the pair of registration rollers 8 and 10. The shutter members 1a and 1b are provided so as to be rotatable independently from the driven registration roller shaft 7 of the driven registration roller 8 and are movable in a first position, a second position, and a third position. The first position is a position where a leading edge of the sheet 4 does not abut on the abutting surfaces 3a and 3b (FIG. 2), the second position is a position which is disposed further downstream of the sheet conveyance direction than the first position to latch the leading edge of the sheet 4 (FIG. 3), and the third position is a position which allows passage of the sheet 4 (FIG. 4).

In the upstream side of the sheet conveyance direction of nip portions of the driven registration roller 8 and the drive registration roller 10, the abutting surfaces 3a and 3b of the shutter members 1a and 1b are disposed (FIGS. 1 and 2) and the leading edge of the sheet 4 abuts on the abutting surfaces 3a and 3b before entering the nip portion. The leading edge of the sheet 4 pushes the abutting surfaces 3a and 3b so that the shutter members 1a and 1b independently rotate around the driven registration roller shaft 7.

The shutter members 1a and 1b may freely rotate between the first position in which the leading edge of the sheet 4 does not abut on the abutting surfaces 3a and 3b (FIG. 2) and the second position in which the leading edge of the sheet 4 is latched (FIG. 3). However, in order to allow the shutter members 1a and 1b to rotate beyond the second position and move to the third position which allows the sheet 4 to pass (FIG. 4), both shutter members 1a and 1b which are all of the shutter members need to be in the second position.

For example, when the shutter member 1b rotates prior to the shutter member 1a, the shutter member 1b stops the rotation in the second position to wait until the shutter member 1a reaches the second position. If the second position is set in a predetermined position where the skew feeding of the sheet is appropriately corrected, an advancing side of the skew feeding of the leading edge of the sheet 4 needs to wait a lagging side by this operation so that the skew feeding of the sheet is corrected (FIGS. 5A and 5B). When both shutter members 1a and 1b reach the second position, the shutter members 1a and 1b are rotatable beyond the second position. Thereafter, the leading edge of the sheet 4 enters the nip portions of the pair of registration rollers 8 and 10 while pushing the shutter members 1a and 1b and the shutter members 1a and 1b to the third position by the leading edge of the sheet 4 which is conveyed to the pair of registration rollers 8 and 10 (FIG. 4). If the sheet 4 completely passes the skewed sheet correcting device R, the shutter members 1a and 1b move from the third position to the second position by the urging force which will be described below and eventually return to the first position.

Next, as for the first embodiment that achieves a series of skew feeding correcting operations in which the shutter members 1a and 1b reach from the first position to the second position and the third position, pass the sheet, and then returns to the first position, the motions and the roles of component parts will be described in detail.

The skewed sheet correcting device R is provided with a movement regulating portion configured as described below. The movement regulating portion abuts on a shutter member of the plurality of shutter members 1a and 1b which does not move to the second position to regulate the shutter member which moves to the second position in the second position. Further, all of the shutter members move to the second position to release the abutting state so that the movement regulating portion allows all of the shutter members which move to the second position to move to the third position.

The movement regulating portion according to this embodiment includes levers 2a and 2b as lever members (interlocking member) and a stopper member 5 which will be described below.

As illustrated in FIGS. 2 and 6, in a rotational direction of the shutter members 1a and 1b, in an edge which is not an edge where the abutting surfaces 3a and 3b of the shutter members 1a and 1b are disposed, the levers 2a and 2b are disposed. The levers 2a and 2b are rotatable around the same rotational support 6. Further, the levers 2a and 2b are continuously applied with a force in a direction of an arrow A of FIG. 6 by the torsion coil springs 15a and 15b as an urging part. The urging force by the torsion coil springs 15a and 15b is transmitted to the shutter members 1a and 1b through the levers 2a and 2b and continuously urges the shutter members 1a and 1b in a position of the first position. Here, the urging force of the torsion coil springs 15a and 15b is set to be low enough to push the shutter members 1a and 1b to the second and third positions also in a sheet having the lowest rigidity (for example, a thin paper having a basis weight of 52 g/m²) among the types of sheets which become a target of the image formation.

As illustrated in FIGS. 6 and 7, if the shutter members 1a and 1b are pushed by the leading edge of the sheet 4 so as to rotate, in connection with this, the levers 2a and 2b rotate around the rotational support 6. The levers 2a and 2b abut the protrusions 11a and 11b provided on the stopper member 5 as illustrated in FIGS. 7 and 8 in a position where the levers rotate by a predetermined amount from an initial position illustrated in FIG. 6 so that the levers do not rotate around the rotational support 6 anymore.

In the meantime, as illustrated in FIGS. 9A and 9B, a hook unit 13 is provided at one end of the rotational support 6 and the rotational support 6 is slidable along a groove of the guide 12. Further, if both the shutter members 1a and 1b move to the second position, the abutting state of the levers 2a and 2b against the side of the stopper member 5 is released and the levers 2a and 2b enter the groove 11c of the stopper member 5 as illustrated in FIG. 10. However, since the levers 2a and 2b are connected to each other through the common rotational support 6, if one of the levers cannot enter the groove 11c of the stopper member 5, the other lever cannot enter the groove 11c of the stopper member 5. In other words, until both shutter members 1a and 1b reach the second position, an end face 14a of the lever 2a or an end face 14b of the lever 2b illustrated in FIG. 11 abuts on the side of the stopper member 5. Therefore, the levers 2a and 2b may not enter the groove 11c of the stopper member 5.

For example, as illustrated in FIG. 12B, when the shutter member 1b moves to the second position first, the lever 2b abuts on the abutting unit 11b of the stopper member 5 so that the lever 2b cannot rotate around the rotational support 6 anymore. Thereafter, since the lever 2b is continuously pushed by the shutter member 1b, the lever 2b may enter the groove 11c of the stopper member 5 while the rotational support 6 is slid in a groove of a guide 12. However, when the shutter member 1a does not reach the second position, the end face 14a of the lever 2a abuts on the side of the stopper member 5. Therefore, the lever 2a cannot enter the groove 11c of the stopper member 5. Accordingly, the lever 2b also cannot enter along the groove 11c of the stopper member 5. Thus, when the shutter member 1a does not reach the second position, the shutter member 1b cannot rotate beyond the second position.

In the meantime, as illustrated in FIG. 12A, similarly, in the case where the shutter member 1a moves to the second position first, the shutter member 1a cannot rotate beyond the second position when the shutter member 1b does not reach the second position.

While the shutter member 1b is in the second position and stops the rotation, the sheet 4 is pushed in by the pair of conveying rollers 16 which is the first conveying portion. Therefore, as illustrated in FIGS. 5A and 5B, the leading edge of the sheet 4 pivots to push the abutting surface 3a therein. Accordingly, the shutter member 1a starts the rotation and the lever 2a which is pushed by the shutter member 1a also starts the rotation. As a result, at the time when the shutter member 1a moves to the second position and the lever 2a abuts on the protrusion 11a as illustrated in FIG. 7, the abutting state of the lever 2a against the side of the stopper member 5 is released so that the lever 2a is capable of entering the groove of the stopper member 5.

Thus, since both the levers 2a and 2b are capable of entering the groove of the stopper member 5, as illustrated in FIGS. 10 and 13A and 13B, the shutter members 1a and 1b pushed at the leading edge of the sheet 4 rotate while allowing the levers 2a and 2b to enter the groove the stopper member 5. The sheet is nipped by the pair of registration rollers 8 and 10 while the shutter members 1a and 1b is moved by being pushed by the sheet. If the shutter members 1a and 1b rotates at a constant amount, the shutter members 1a and 1b are in the third position and the leading edge of the sheet 4 passes the shutter members 1a and 1b as illustrated in FIG. 4.

When a trailing edge of the sheet completely passes the shutter members 1a and 1b, the levers 2a and 2b are extruded from the groove of the stopper member 5 by the urging force of the torsion coil springs 15a and 15b (force in a direction of an arrow B illustrated in FIG. 14A) (FIGS. 14A and 14B). In other words, the urging force of the torsion coil springs 15a and 15b is applied in a direction that rotates the levers 2a and 2b around the rotational support 6 (in a direction of an arrow A illustrated in FIGS. 6 and 14B) and the levers 2a and 2b returns to the state of FIG. 6. In connection with a series of motions of the levers 2a and 2b, the shutter members 1a and 1b return from the third position to the second and first positions.

As described above, according to this embodiment, under a condition where the plurality of shutter members 1a and 1b are pushed to the second position that latches the leading edge of the sheet, all of the plurality of shutter members 1a and 1b is retracted from the second position to the third position that allows the sheet to pass. Therefore, it is possible to surely correct the skew feeding of a sheet regardless of the rigidity of the sheet without increasing the size and the cost of the device.

Second Embodiment

Next, as for a second embodiment that achieves a series of skew feeding correcting operations, motions and roles of component parts will be described in detail.

Also in the second embodiment, similarly to the above-described embodiment, the skewed sheet correcting device R has a movement regulating portion that is configured as described below. The movement regulating portion according to this embodiment includes a cylinder member 38 as a rotational member which will be described below, slide pins 37a and 37b as a sliding member (interlocking member), and a stopper member 31.

As illustrated in FIG. 17, the shutter members 1a and 1b are urged to the first position by the urging force of the torsion coil springs 39a and 39b as a urging portion. Further, in an edge which is not an edge where sheet abutting surfaces of the shutter members 1a and 1b are disposed, skewed planes 35a and 35b are disposed as illustrated in FIG. 18. In a position that contacts with the skewed planes 35a and 35b, the slide pins 37a and 37b are disposed. That is, slide pins 37a and 37b are provided so as to correspond to the shutter members 1a and 1b, respectively.

In the meantime, as illustrated in FIG. 17, at an inside of the shutter members 1a and 1b, the cylinder member 38 is provided so as to be rotatable around the driven registration roller shaft 7. The cylinder member 38 is applied with a force in a direction of an arrow of FIG. 19 by an urging portion (eccentricity of a center of the cylinder member, a torsion coil spring, or a compression spring) which is not illustrated. Further, a groove 33 is provided in the cylinder member 38 in an axial direction as illustrated in FIG. 20.

As illustrated in FIG. 20, the above-mentioned slide pins 37a and 37b are disposed in the groove 33 of the cylinder member 38. The slide pins 37a and 37b abut on the shutter members 1a and 1b, respectively, so as to be slidable in an axial direction along the groove 33 of the cylinder member 38 in accordance with the movement of the shutter members 1a and 1b. Further, the slide pins 37a and 37b rotate around the driven registration roller shaft 7 together with the cylinder member 38. Further, a compression spring 30 is provided in the groove 33 so as to outwardly apply a force to the slide pins 37a and 37b.

Further, as illustrated in FIG. 17, the stopper member 31 is disposed outside the shutter members 1a and 1b so as to be fixed. As illustrated in FIG. 20, the stopper member 31 has edges 31a and 31b and the slide pins 37a and 37b abut on the edges 31a and 31b, respectively. The stopper member 31 abuts on a slide pin which corresponds to a shutter member that does not move to the second position so as to regulate the shutter member which moves to the second position from moving to the third position.

Hereinafter, operations of members that correct a sheet fed to be skewed will be described. Here, operations of members when the shutter member 1b is pushed in the sheet prior to the shutter member 1a will be described.

If the shutter member 1b is pushed in the sheet to start the rotation, as illustrated in FIG. 21, the slide pin 37b is pushed in a skewed plane 35b of the shutter member 1b. However, since the slide pin 37b abuts on the edge 31b of the stopper member 31, the slide pin cannot rotate for every cylinder member 38. However, the slide pin 37b is slidable in the axial direction so that as illustrated in FIG. 21, the slide pin 37b slides in the axial direction along the groove 33 in connection with the rotation of the shutter member 1b.

If the shutter member 1b is pushed in the sheet to rotate to the second position, the slide pin 37b is deviated from the edge 31b of the stopper member 31. In this case, the shutter member 1b pushes the abutting surface 38b of the cylinder member 38 to rotate the cylinder member 38. However, if the shutter member 1a does not reach the second position, the slide pin 37a abuts on the edge 31a of the stopper member 31. Accordingly, the cylinder member 38 does not rotate. As a result, as illustrated in FIG. 21, the shutter member 1b cannot rotate over the second position.

Even while the shutter member 1b stops in the second position, the sheet 4 is pushed in by the pair of conveying rollers 16 which is the first conveying portion. Therefore, as illustrated in FIGS. 5A and 5B, the leading edge of the sheet 4 pivots to push the abutting surface 3a of the shutter member 1a. By doing this, the shutter member 1a starts to rotate and the slide pin 37a which is pushed in the skewed plane 35a of the shutter member 1a starts to slide along the groove 33 in the axial direction.

As a result, at a time when the shutter member 1a moves to the second position and the slide pin 37a is deviated from the edge 31a of the shutter member 1a as illustrated in FIG. 22, the cylinder member 38 is rotatable. Accordingly, the shutter members 1a and 1b are also rotatable beyond the second position. As illustrated in FIG. 23, the shutter members 1a and 1b which are pushed in the leading edge of the sheet 4 pushes the abutting surfaces 38a and 38b of the cylinder member 38 and rotates together with the cylinder member 38. If the shutter members 1a and 1b rotate at a constant rotation amount, the shutter members 1a and 1b are in the third position and the leading edge of the sheet 4 passes the shutter members 1a and 1b as illustrated in FIG. 4.

If the trailing edge of the sheet 4 completely passes the shutter members 1a and 1b, the shutter members 1a and 1b return from the third position to the second and first positions by the urging force of the torsion coil springs 39a and 39b. Further, the cylinder member 38 in which the pushing by the shutter members 1a and 1b is released returns to the initial position by a urging portion which is not illustrated. If the cylinder member 38 returns to an initial position, the slide pins 37a and 37b return to the outside by the urging force of the compression spring 30.

As described above, this embodiment may achieve the same effect as the above-described embodiment. That is, under a condition where the plurality of shutter members 1a and 1b is pushed to the second position that latches the leading edge of the sheet, all of the plurality of shutter members 1a and 1b is retracted from the second position to the third position that allows the sheet to pass. Therefore, it is possible to surely correct the skew feeding of a sheet regardless of the rigidity of the sheet without increasing the size and the cost of the device.

Other Embodiments

In the above-described embodiment, as the process cartridge which is detachably attachable to the image forming apparatus, the process cartridge having the photosensitive drum, and a charger, a development portion, and a cleaning portion which serve as a processor which operates for the photosensitive drum integrally combined therein is described. However, the process cartridge is not limited thereto. The processor cartridge may have any one of the charger, a development portion, and the cleaning portion other than the photosensitive drum to be integrally combined.

In the above-described embodiment, a configuration where the process cartridge including the photosensitive drum is detachably attachable to the image forming apparatus is described, but the invention is not limited thereto. For example, an image forming apparatus may have configuration members which are assembled therein or have detachable configuration members.

In the above-described embodiment, even though a printer is exemplified as an image forming apparatus, the invention is not limited thereto. For example, the image forming apparatus may be other image forming apparatus such as a copying machine or a facsimile or other image forming apparatus such as a multifunctional peripheral in which functions of the copying machine and the facsimile are combined. If the present invention is applied to the skewed sheet correcting device used in the image forming apparatus, the same effect may be obtained.

Further, in the above-described embodiment, even though a configuration in which the skewed sheet correcting device that corrects the skew feeding of the sheet is applied to the conveying apparatus that conveys the sheet in the image forming portion that forms an image on the sheet such as a recording sheet as a recording target is exemplified, the invention is not limited thereto. For example, if the skewed sheet correcting device that corrects the skew feeding of the sheet is applied to the conveying apparatus that conveys the sheet to an image reading unit that reads an image on the sheet such as an original as a reading target, the same effect may be obtained.

In the above-described embodiment, even though an electrophotographic system is exemplified as a recording system, the invention is not limited thereto. For example, other recording system such as an inkjet system may be applied thereto.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2012-015307, filed Jan. 27, 2012, which is hereby incorporated by reference herein in its entirety.

Claims

1. A skewed sheet correcting device, comprising: a conveying portion which conveys a sheet;first and second shutter members which are arranged along a width direction perpendicular to the sheet conveyance direction and disposed downstream of the conveying portion in the sheet conveyance direction, wherein the first and second shutter members move to a first position in which the shutter members are pushed to be movable by a leading edge of the sheet which is conveyed by the conveying portion, a second position which is disposed further downstream than the first position in the sheet conveyance direction to latch the leading edge of the sheet, and a third position which allows the sheet to pass; anda movement regulating portion which, when the first shutter member does not move to the second position, regulates the second shutter member that has moved in the second position in the second position, when the second shutter member does not move to the second position, regulates the first shutter member which has moved in the second position in the second position, and, when both the first shutter member and the second shutter member move to the second position, allows the first and second shutter members to move to the third position.

2. The skewed sheet correcting device according to claim 1, wherein the movement regulating portion includes:a first lever member which rotates in connection with the first shutter member;a second lever member which rotates around a common rotational shaft to the first lever member in connection with the second shutter member; anda stopper member which, when the first shutter member does not move to the second position, regulates the movement of the second shutter member that has moved in the second position to the third position by abutting on the first lever member, and, when the second shutter member does not move to the second position, regulates the movement of the first shutter member that has moved in the second position to the third position by abutting on the second lever member, andboth the first shutter member and the second shutter member rotate to the second position to release an abutting state of the first and second lever members on the stopper member so that the first and second shutter members move to the third position.

3. The skewed sheet correcting device according to claim 1, wherein the movement regulating portion includes:a rotating member which is pushed by the first and second shutter members to rotate together with the first and second shutter members;a first slide member which is disposed in the rotating member so as to correspond to the first shutter member and moves in an axial direction with respect to the rotating member in accordance with the movement of the first shutter member;a second slide member which is disposed in the rotating member so as to correspond to the second shutter member and moves in an axial direction with respect to the rotating member in accordance with the movement of the second shutter member; anda stopper member which, when the first shutter member does not move to the second position, regulates the movement of the second shutter member that has moved in the second position to the third position by abutting on the first slide member, and, when the second shutter member does not move to the first position, regulates the movement of the first shutter member that has moved the first position to the third position by abutting on the second slide member, andthe first slide member and the second slide member move as both the first shutter member and the second shutter member move to the second position to release an abutting state of the first and second slide members on the stopper member so that the first and second shutter members move to the third position.

4. The skewed sheet correcting device according to claim 1, further comprising a pair of rollers which is disposed downstream of the conveying portion in the sheet conveyance direction, wherein the sheet is nipped by the pair of rollers while the first and second shutter is moved by being pushed by the sheet.

5. The skewed sheet correcting device according to claim 1, further comprising a urging portion which applies a force to the first and second shutter members at the first position.

6. An image forming apparatus, comprising: an image forming portion which forms an image on a sheet; anda sheet conveying apparatus which conveys the sheet to the image forming portion,wherein the sheet conveying apparatus includes:a conveying portion which conveys the sheet;first and second shutter members which are arranged along a width direction perpendicular to a sheet conveyance direction and disposed downstream of the conveying portion in the sheet conveyance direction, wherein the first and second shutter members move to a first position in which the first and second shutter members are pushed to be movable by a leading edge of the sheet which is conveyed by the conveying portion, a second position which is disposed further downstream than the first position in the sheet conveyance direction to latch the leading edge of the sheet, and a third position which allows the sheet to pass; anda movement regulating portion which, when the first shutter member does not move to the second position, regulates the second shutter member that has moved in the second position in the second position, when the second shutter member does not move to the second position, regulates the first shutter member that has moved in the second position in the second position, and, when both the first shutter member and the second shutter member move to the second position, allows the first and second shutter members to move in the third position.

7. The image forming apparatus according to claim 6, wherein the movement regulating portion includes: a first lever member which rotates in connection with the first shutter member;a second lever member which rotates around a common rotational shaft to the first lever member in connection with the second shutter member; anda stopper member which, when the first shutter member does not move to the second position, regulates the movement of the second shutter member that has moved in the second position to the third position by abutting on the first lever member, and, when the second shutter member does not move to the second position, regulates the movement of the first shutter member that has moved in the second position to the third position by abutting on the second lever member, andboth the first shutter member and the second shutter member rotate to the second position to release an abutting state of the first and second lever members on the stopper member so that the first and second shutter member move to the third position.

8. The image forming apparatus according to claim 6, wherein the movement regulating portion includes:a rotating member which is pushed by the first and second shutter members to rotate together with the first and second shutter members;a first slide member which is disposed in the rotating member so as to correspond to the first shutter member and moves in an axial direction with respect to the rotating member in accordance with the movement of the first shutter member;a second slide member which is disposed in the rotating member so as to correspond to the second shutter member and moves in an axial direction with respect to the rotating member in accordance with the movement of the second shutter member; anda stopper member which, when the first shutter member does not move to the second position, regulates the movement of the second shutter member that has moved in the second position to the third position by abutting on the first slide member, and, when the second shutter member does not move to the first position, regulates the movement of the first shutter member that has moved to the first position to the third position by abutting on the second slide member, andthe first slide member and the second slide member move as both the first shutter member and the second shutter member move to the second position to release the abutting state of the first and second slide members against the stopper member so that the first and second shutter member move to the third position.

9. The image forming apparatus according to claim 6, further comprising a pair of rollers which is disposed downstream of the conveying portion in the sheet conveyance direction, wherein the sheet is nipped by the pair of rollers while the first and second shutter is moved by being pushed by the sheet.

10. The image forming apparatus according to claim 6, further comprising a urging portion which applies a force to the first and second shutter members at the first position.

11. A skewed sheet correcting device, comprising: a conveying portion which conveys a sheet;first and second shutter members which are arranged along a width direction perpendicular to the sheet conveyance direction and disposed downstream of the conveying portion in the sheet conveyance direction, wherein the first and second shutter members move to a first position in which the shutter members are pushed to be movable by a leading edge of the sheet which is conveyed by the first conveying portion, a second position which is disposed further downstream than the first position in the sheet conveyance direction to latch the leading edge of the sheet, and a third position which allows the sheet to pass;a first interlocking member which interlocks with the first shutter member;a second interlocking member which interlocks with the second shutter member;a stopper member which, when the first shutter member does not move to the second position, regulates the movement of the second shutter member that has moved to the second position to the third position by abutting on the first interlocking member, and, when the second shutter member does not move to the second position, regulates the movement of the first shutter member that has moved to the second position to the third position by abutting on the second interlocking member, andthe abutting state of the first and second interlocking members against the stopper member is released if both the first shutter member and the second shutter member rotate to the second position, thereby the first and second shutter member can move to the third position.

12. The skewed sheet correcting device according to claim 11, further comprising a pair of rollers which is disposed downstream of the conveying portion in the sheet conveyance direction, wherein the sheet is nipped by the pair of rollers while the first and second shutter is moved by being pushed by the sheet.