Patent Application
20230017154
This disclosure relates to a sheet conveyance apparatus conveying a sheet, and an image forming apparatus and an image forming system provided with same.
Hitherto, a registration apparatus of an obliquely conveying registration type which conveys a sheet while abutting a side edge of the sheet against a reference member is suggested formed between a reference edge and a non-reference edge adjacent to the reference edge is determined using a side edge of the sheet as the reference edge. Then, based on this angle, an angle of the reference member is adjusted such that the deviation in margins at the reference and nonreference edges becomes even.
Recently, sometimes, a post-processing apparatus is coupled to an image forming apparatus such as a printer, and the post-processing such as a cutting process and a stapling process is performed in the post-processing apparatus. At this time, an edge of the sheet is usually used as a processing reference in the post-processing, and, sometimes, there is a case where a reference (side edge) for the image formation and a skew correction in the image forming apparatus does not match the processing reference for the post-processing.
For example, in a case where, after the skew correction and the image formation have been performed using the side edge as the reference in the registration apparatus described in Japanese Patent Laid-Open No. 2011-98790, the post-processing is performed using an edge adjacent to the side edge as the reference in the post-processing apparatus, a positional variation of an image on the sheet after the post-processing occurs. Therefore, especially in a case where a squareness of the sheet is low, there is a risk that the quality of the final deliverables is degraded.
According to an aspect of the present invention, a sheet conveyance apparatus includes a conveyance guide configured to guide a sheet along a conveyance center line extending in a conveyance direction, a reference member including an abutment surface extending along the conveyance direction, a conveyance unit configured to convey the sheet while abutting a first edge of the sheet against the abutment surface of the reference member, a detection unit configured to detect a first angle formed between the first edge of the sheet and a second edge adjacent to the first edge, a moving unit configured to move the reference member so as to change a second angle formed between the abutment surface and the conveyance center line, and a control unit configured to perform a movement process in which the moving unit moves the reference member such that, when the first angle is referred to as α, the second angle becomes an absolute value of a difference 90 degrees minus α.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, details of representative embodiments of this disclosure will be described. To be noted, embodiments described below exemplarily describe this disclosure, and configurations, and sizes, materials, shapes, relative arrangements, the control, and the like of components described below do not limit a scope of this disclosure unless otherwise specifically stated.
As shown in
The image forming apparatus 100 includes an image forming unit 513, a sheet feed unit 100B, and a conveyance apparatus 100D. The image forming unit 513 includes four process cartridges PY, PM, PC, and PBk forming four colors of toner images of yellow (Y), magenta (M), cyan (C), and black (K), and exposing units 511Y, 511M, 511C, and 511Bk. To be noted, the four process cartridges PY, PM, PC, and PBk are the same in a configuration except for differences in colors in which images are formed. Accordingly, only the configuration and an image forming process of the process cartridge PY will be described herein, and descriptions of the other process cartridges PM, PC, and PBk will be omitted.
The process cartridge PY includes a photosensitive drum 508, a charge roller, not shown, a cleaner 509, and a developing unit 510. The photosensitive drum 508 is constructed by coating an organic photoconductive layer on an outer circumferential surface of an aluminum cylinder, and rotated by a drive motor, not shown. Further, an intermediate transfer belt 506 rotated by a drive roller 504 in an arrow G direction is disposed in the image forming unit 513, and wound around a tension roller 505, the drive roller 504, and a secondary transfer inner roller 503. Primary transfer rollers 507Y, 507M, 507C, and 507Bk are disposed inside of the intermediate transfer belt 506, and a secondary transfer outer roller 56 is disposed outside of the intermediate transfer belt 506 so as to face the secondary transfer inner roller 503.
The sheet feed unit 100B includes a sheet storage portion 51 storing the sheet S, a lift-up unit 52 ascending and descending while stacking the sheet S, and a sheet feed portion 53 feeding the sheet S on the lift-up unit 52. While a pneumatic conveyance type pneumatically sucking and conveying the sheet S by separating the sheet into one sheet at a time is employed in this embodiment, it is not limited to this. For example, for the sheet feed portion 53, it is acceptable to employ a roller conveyance type conveying the sheet by a pickup roller and the like, and an electrostatic attraction type sucking and conveying the sheet by electrostatic force.
The conveyance apparatus 100D includes a conveyance unit 54, a skew correction unit 55, a pre-fixing conveyance unit 57, a fixing unit 58, a branch conveyance unit 59, a reverse conveyance unit 501, and a duplex conveyance unit 502. These units each include a conveyance roller pair for conveying the sheet. The fixing unit 58 includes a fixing nip portion 58a for conveying the sheet by nipping.
Next, an image forming operation of the image forming apparatus 100 configured as described above will be described. When an image signal is input to the exposing unit 511Y from a personal computer, not shown, and the like, the exposing unit 511Y irradiates a laser beam corresponding to the image signal on the photosensitive drum 508 of the process cartridge PY.
At this time, a surface of the photosensitive drum 508 has been uniformly charged in a predetermined polarity and voltage beforehand, and an electrostatic latent image is formed on the surface by the laser beam irradiated from the exposing unit 511Y via a mirror. The electrostatic latent image formed on the photosensitive drum 508 is developed by the developing unit 510, and a toner image of yellow (Y) is formed on the photosensitive drum 508.
Similarly, the exposing units 511M, 511C, and 511Bk irradiate the respective photosensitive drums of the process cartridges PM, PC, and PBk with the laser beam, and toner images of magenta (M), cyan (C), and black (K) are formed on the respective photosensitive drums. The toner images of the respective colors formed on the respective photosensitive drums are transferred onto the intermediate transfer belt 506 by the primary transfer rollers 507Y, 507M, 507C, and 507Bk. Then, by the intermediate transfer belt 506 rotated by the drive roller 504, a full color toner image is conveyed to a secondary transfer nip T2 formed by the secondary transfer inner and outer rollers 503 and 56. A toner remained on the photosensitive drum 508 is collected by the cleaner 509. To be noted, the image forming processes of the respective colors are performed in the timing superimposing the toner image on an upstream toner image primarily transferred onto the intermediate transfer belt 506.
In parallel with this image forming process, the sheet S is fed from the sheet feed unit 100B, and the sheet S is conveyed to a duplex conveyance path R of the duplex conveyance unit 502 via a conveyance path 91. Then, the sheet S passes a conveyance path 54a of the conveyance unit 54, and is conveyed to the skew correction unit 55. The skew of the sheet S is corrected by the skew correction unit 55, and the sheet S is conveyed to the secondary transfer nip T2 by a registration roller pair 7 in predetermined conveyance timing. The full color toner image on the intermediate transfer belt 506 is transferred onto a first surface (front surface) of the sheet S by a secondary transfer bias applied to the secondary transfer outer roller 56. A remained toner remained on the intermediate transfer belt 506 is collected by a belt cleaner 2.
The sheet S onto which the toner image has been transferred is conveyed to the fixing unit 58 by the pre-fixing conveyance unit 57. Then, the sheet S is guided to the fixing nip portion 58a of the fixing unit 58, and, by proving predetermined heat and pressure, the toner is melted and bonded (fixed). With respect to the sheet S passed through the fixing unit 58, the path selection of selecting a path between the conveyance to the post-processing apparatus 600 and the conveyance to the reverse conveyance unit 501 is performed by the branch conveyance unit 59. To be noted, it is also possible to perform the so called facedown conveyance conveying the sheet S such that the sheet S is conveyed to a sheet discharge tray 500 with the sheet S inverted so as to turn the first surface, on which the image has been formed at the secondary transfer nip T2, to the underside.
In a case where the image is formed on only one side of the sheet S, the sheet S is conveyed from the branch conveyance unit 59 to the post-processing apparatus 600. In a case where the images are formed on both sides of the sheet S, the sheet S is conveyed to the reverse conveyance unit 501 by the branch conveyance unit 59. Then, the sheet S is switchbacked by the reverse conveyance unit 501. The sheet S which has been switchbacked is conveyed from the reverse conveyance unit 501 to the duplex conveyance unit 502, and guided to the conveyance unit 54 and the skew correction unit 55. Thereafter, the image is formed on a second surface (back surface) of the sheet S at the secondary transfer nip T2, and discharged to the post-processing apparatus 600.
Next, the post-processing apparatus 600 will be described in detail. The post-processing apparatus 600 is coupled to the image forming apparatus 100, and includes a conveyance unit 601, a swing roller 603, a stapling unit 620, and a sheet discharge tray 610. The stapling unit 620 includes a process tray 602 for loading the sheet S, a regulation plate 604 for regulating a position of a trailing edge of the sheet S stacked on the process tray 602, and a stapler 605 for performing a stapling process on the sheet S.
The post-processing apparatus 600 receives the sheet S from the branch conveyance unit 59 of the image forming apparatus 100, and conveys the sheet S by the conveyance unit 601. The swing roller 603 is capable of pivoting between upper and lower positions, and positioned in the upper position when the conveyance unit 601 discharges the sheet S to the sheet discharge tray 610. When the sheet S has been discharged to the process tray 602, the swing roller 603 pivots from the upper position to the lower position.
In a case where the stapling process is not performed on the sheet S, the swing roller 603 discharges the sheet S to the sheet discharge tray 610 as it is. On the other hand, in a case where the stapling process is performed on the sheet S, the swing roller 603 conveys the sheet S on the process tray 602 toward the regulation plate 604. Then, since the trailing edge of the sheet S abuts against the regulation plate 604, a position of the sheet S in a conveyance direction is regulated, and also the skew of the sheet S is corrected. After an alignment process as described above has been performed with respect to a predetermined number of sheets of the sheet S, the stapler 605 performs the stapling process with respect to the predetermined number of sheets of the sheet S. A sheet bundle which has been provided with the stapling process is discharged to the sheet discharge tray 610 by the swing roller 603.
Next, using
With a fixed guide 12, described later, a lower conveyance guide 13, and a movable guide 25, the upstream conveyance guide 11 constructs a conveyance guide portion 45 guiding the sheet S in the conveyance direction F in the skew correction unit 55. The conveyance guide portion 45 forms a conveyance path CP through which the sheet S passes, and a conveyance center line CT1 of the conveyance path CP, serving as a conveyance path, extends in the conveyance direction F. In this embodiment, a center standard using the conveyance center line CT1 as a reference for the conveyance of the sheet S and the image formation in the image forming unit 513 is adopted.
The conveyance roller pair 14b is disposed downstream of the conveyance roller pair 14a in the conveyance direction F, and the CIS sensor 101 is disposed between the conveyance roller pairs 14a and 14b in the conveyance direction F. Further, the pre-registration sensors 102a and 102b are disposed downstream of the conveyance roller pair 14b in the conveyance direction F. The CIS sensor 101 and the pre-registration sensors 102a and 102b construct a detection unit 47 detecting an angle α, described later. To be noted, in the detection unit 47, it is acceptable to include part of the control unit 9 for determining the angle α based on detection results of the respective sensors. Further, the detection unit 47 is not limited to the configuration of this embodiment, and it is acceptable to determine the angle α by imaging the sheet, for example, by a camera and the like.
The CIS sensor 101 is disposed so as to be capable of detecting a position of an abutment reference edge Es which is one side of the sheet S in a width direction W orthogonal to the conveyance direction F. In particular, by acquiring the image at fixed time intervals, the CIS sensor 101 is capable of acquiring a positional change of the abutment reference edge Es as a sequential image at the time when the sheet S passes through a detection area of the CIS sensor 101.
The pre-registration sensors 102a and 102b are disposed in symmetrical positions in the width direction W with respect to the conveyance center line CT1. The pre-registration sensors 102a and 102b each output a signal of Low in a case where the sheet S is absent in a detection position, and output a signal of High in a case where the sheet S is present in the detection position. Therefore, by a switch of the signal from Low to High, it is possible to detect the timing when the sheet S passes through the respective detection positions of the pre-registration sensors 102a and 102b.
The obliquely conveying portion 42 includes the fixed guide 12 and an obliquely conveying unit 26, and the obliquely conveying unit 26 includes the movable guide 25, obliquely conveying roller pairs 24a to 24c, and a reference member 20. The abutment reference edge Es of the sheet S is abutted against the reference member 20, and the reference member 20 includes an abutment surface 20a extending along the conveyance direction F. Further, the reference member 20 is pivotable around a pivot shaft 21 as a center, and urged toward a cam 22 by an urging spring 23.
A position of the reference member 20 in a pivot direction is determined by abutting against the cam 22, and, since the cam 22 is rotatably driven by an angle adjustment motor 31, the reference member 20 pivots around the pivot shaft 21 as the center. As described above, by driving the angle adjustment motor 31, serving as a moving unit, it is possible to change an angle β (refer to
Each of the obliquely conveying roller pairs 24a to 24c includes a roller pair, and a rotation shaft of at least one side of the roller pair inclines with respect to the width direction W and the conveyance direction F. Thereby, the sheet S is conveyed toward the abutment surface 20a by the obliquely conveying roller pairs 24a to 24c. That is, the obliquely conveying roller pairs 24a to 24c, serving as a conveyance unit, conveys the sheet S while abutting the abutment reference edge Es of the sheet S against the abutment surface 20a of the reference member 20. Thereby, the sheet S is conveyed in a state where the abutment reference edge Es is in slide contact with the abutment surface 20a, and a posture of the sheet S follows the abutment surface 20a. Thus, the skew of the sheet S is corrected.
The movable guide 25, the obliquely conveying roller pairs 24a to 24c, and the reference member 20 of the obliquely conveying unit 26 are integrally movable in the width direction W by a slide drive motor 32. Further, the obliquely conveying unit 26 is movable to a standby position Pw and a retracting position Pe in accordance with a size of the sheet S which is conveyed. In
The obliquely conveying unit 26 moves to and waits in the standby position Pw before the sheet S is conveyed. The standby position Pw means a position in which an abutting margin Xo is added to an edge position Xp of the sheet S as defined by the center standard. The abutting margin Xo is a distance for conveying the sheet S by following the abutment surface 20a without colliding with an upstream end of the reference member 20 in the conveyance direction F.
Then, having delivered the sheet S to the registration roller pair 7, the obliquely conveying unit 26 moves from the standby position Pw to the retracting position Pe. The retracting position Pe is a position in which a retracting distance Xe is added to the standby position Pw, and the retracting distance Xe is a distance for retracting the reference member 20 in the width direction W such that the reference member 20 does not interfere with the conveyance of the sheet S.
As described above, the obliquely conveying unit 26 is positioned in the retracting position Pe when the sheet S is not present in the obliquely conveying portion 42, and moves to the standby position Pw when the sheet S has entered the obliquely conveying portion 42, and returns to the retracting position Pe again after the sheet S has been delivered to the registration roller pair 7.
To be noted, when the obliquely conveying roller pairs 24a to 24c start the skew correction of the sheet S, it is suitable that the conveyance roller pairs 14a and 14b do not nip the sheet S. In this embodiment, the control unit 9 counts a predetermined time from the timing in which the pre-registration sensors 102a and 102b have detected a leading edge of the sheet. Then, the control unit 9 controls such that nips of the conveyance roller pairs 14a and 14b are released in the timing in which the leading edge of the sheet S reaches the obliquely conveying roller pair 24a after the predetermined time has passed.
The slide portion 43 includes the lower conveyance guide 13, the registration roller pair 7, a registration drive motor 33, a registration slide motor 34, and a pre-registration sensor 103. The registration roller pair 7, serving as a downstream conveyance portion, is disposed downstream of the obliquely conveying roller pairs 24a to 24c in the conveyance direction F, and conveys the sheet S in the conveyance direction F. The pre-registration sensor 103 is disposed upstream of the registration roller pair 7 in the conveyance direction F, and, similar to the pre-registration sensors 102a and 102b, is capable of detecting the timing of the sheet S passing through the detection position.
The registration roller pair 7 is rotatable by the registration drive motor 33, and slidable in the width direction W by the registration slide motor 34. After the sheet S has been delivered from the obliquely conveying roller pairs 24a to 24c, so as to align a position of the sheet S with an image forming position, the registration roller pair 7 slides the sheet S in the width direction W in a state nipping the sheet S. A movement amount of the registration roller pair 7 in the width direction W at this time is the sum of the abutting margin Xo and a slide correction amount Xf, described later.
To be noted, when the registration roller pair 7 slides in the width direction W, it is suitable that the obliquely conveying roller pairs 24a to 24c do not nip the sheet S. In this embodiment, the control unit 9 releases nips of the obliquely conveying roller pairs 24a to 24c based on the timing in which the pre-registration sensor 103 has detected the sheet S. Further, the control unit 9 releases a nip of the registration roller pair 7 based on the timing in which the sheet S has been delivered to the secondary transfer nip T2, and returns the registration roller pair 7 to a standby position before a slide movement.
Next, based on
For example, with respect to a sheet A shown in
However, there is a case where a reference edge for the conveyance and the image formation in the image forming apparatus 100 is different from a reference edge in the post-processing apparatus 600. That is, there is a case where, in the image forming apparatus 100, the image is formed on the sheet based on the abutment reference edge Es, serving as a first edge, and, in the post-processing apparatus 600, the post-processing is performed based on a non-reference edge En, serving as a second edge, adjacent to the abutment reference edge Es. For example, as described above, having aligned the sheets by abutting the non-reference edges En of the respective sheets against the regulation plate 604, the post-processing apparatus 600 performs a stapling process of the sheet bundle constituted by these sheets. That is, the stapling process of the sheet bundle is performed with reference to the non-reference edge En. Hereinafter, the reference edge of the sheet S in the stapling process is referred to as a post-processing reference edge.
In this case, if the sheets A and B shown in
To be noted, in the following, the non-reference edge En adjacent to the abutment reference edge Es is assumed to be a downstream edge in the conveyance direction F of the sheet S, namely the leading edge of sheet S. In other words, the abutment reference edge Es is an edge extending along the conveyance direction F of the sheet, and the non-reference edge En is an edge extending along the width direction W orthogonal to the conveyance direction F of the sheet. In this case, having performed the duplex printing on the sheet S, the non-reference edge En abuts against the regulation plate 604, and becomes an alignment reference in the post-processing apparatus 600.
Next, using
As shown in
Θs=tan−1{(X1−X2)/(Vs*(T2−T1))} Equation (1)
Next, as shown in
Θn=tan−1{X102/(Vs*(Tb−Ta))} Equation (2)
By the equations (1) and (2) above, the angle a formed between the abutment reference edge Es and the non-reference edge En is calculated by the following equation.
α=Θs+Θn . . . Equation (3)
Now, in a case where a is not equal to 90 degrees, if the skew correction of the sheet S is performed by the skew correction unit 55 in a state where the angle β of the abutment reference member is kept at 0 degree, the non-reference edge En of the sheet S is inclined by the difference α minus 90 degrees with respect to the width direction W. In a case where the stapling process is performed in the post-processing apparatus 600 with respect to the non-reference edge En, due to the inclination of the non-reference edge En described above, the image formed on the sheet bundle on which the stapling process has been performed varies. Therefore, by setting beforehand the angle β of the reference member 20 at the difference 90 degrees minus α, assuming the counter-clockwise direction as positive, it becomes possible to form the image in line with the non-reference edge En, so that it is possible to reduce variations in the respective images in the sheet bundle.
Next, using
When the sheet S is delivered from the obliquely conveying roller pairs 24a to 24c to the registration roller pair 7, even in a case where a variation arises in the conveyance of the sheet S, it is necessary to surely deliver the sheet S. Therefore, it is common to provide a time in which both of the obliquely conveying roller pairs 24a to 24c and the registration roller pair 7 convey the sheet S at the same time. However, if the sheet S is delivered as described above without sliding the registration roller pair 7, due to the difference between the conveyance direction F of the sheet S and the travelling direction Fs, a rotational moment Ms arises in the sheet S.
Therefore, in this embodiment, the registration roller pair 7 is controlled so as to receive the sheet S while being moved in the width direction W by the registration slide motor 34. The moving velocity Vr of the registration roller pair 7 at the time of receiving the sheet S is calculated as described below by using the conveying velocity Vs in the conveyance direction F of the sheet S and the angle β.
Vr=−Vs·tan β Equation (4)
To be noted, a direction of the moving velocity Vr, as shown by an arrow Fr, from a lower side of a sheet surface of
As described above, the registration roller pair 7 of this embodiment is moved at the velocity Vr in the width direction W (arrow Fr) while conveying the sheet S at the conveying velocity Vs in the conveyance direction F. Thereby, the registration roller pair 7 is able to convey the sheet S in a direction aligned with the travelling direction Fs of the sheet S in the obliquely conveying portion 42, so that it is possible to receive the sheet S without arising the rotational moment in the sheet S. Therefore, it is possible to reduce the skew, the wrinkle, and the damage of the sheet S.
Next, using
A corrected slide amount Xr that is a distance by which the registration roller pair 7 slides the sheet S in the width direction W is an amount in which the slide correction amount Xf is added to the abutting margin Xo described above. The slide correction amount Xf corresponds to the deviation in the width direction W arisen from obliquely conveying the sheet by the angle β with respect to the conveyance direction F in the obliquely conveying portion 42.
As shown in
Xf=(y1+Vs·ΔTc)tan β . . . Equation (5)
Further, the corrected slide amount Xr is expressed by the following equation.
Xr=Xo+Xf . . . Equation (6)
Next, using
Since, in this embodiment, a so-called switchback method reversing the leading and trailing edges of the sheet S is employed in the case performing the duplex printing, a relative inclination angle between the abutment reference edge Es and the non-reference edge En is inverted. That is, with respect to the angle β of the reference member 20, which is equal to the difference 90 degrees minus α at the time printing on the first surface, the angle β of the reference member 20 at the time printing on the second surface becomes minus one, multiplied by the difference 90 degrees minus α.
Further, since the image is formed in a state where the abutment reference edge Es is inclined with respect to the image, at an edge which becomes the leading edge of the second surface (the tailing edge of the first surface), the edge position Xp of the sheet S in the width direction W defined by the center standard of the image is different from the first surface. An edge position correction amount Xpd that is the difference described above is expressed by the following equation when the length of the sheet S in the conveyance direction F is referred to as L.
Xpd =L·tan(−(90°−α)) . . . Equation (7)
Therefore, in the skew correction at the time of printing the second surface of the duplex printing, the angle β of the reference member 20, and the standby position Pw and the retracting position Pe of the reference member 20 are respectively calculated by the following equations.
β=−(90°−α) . . . Equation (8)
Pw=Xp+Xpd+Xo. . . Equation (9)
Pe=Xp+Xpd+Xo+Xe . . . Equation (10)
Next, with reference to
Next, as shown in
In a case where the post-processing reference edge matches the abutment reference edge Es (STEP S5: YES), it is not necessary to change the angle of 0 degree of the reference member 20 as it is, and, also, it is not necessary to retract the obliquely conveying unit 26 to the retracting position Pe. That is, the abutment surface 20a of the reference member 20 becomes parallel to the conveyance direction F. Therefore, in a case where the pre-registration sensor 103 is turned ON (STEP S14: YES) due to the passage of the sheet S, the control unit 9 moves the registration roller pair 7 by the abutting margin Xo in the width direction W after a predetermined count (SPEP S15). Thereby, the control unit 9 ends the processing.
On the other hand, in a case where the post-processing reference edge does not match the abutment reference edge Es (STEP S5: NO), as shown in
Then, as shown in
Next, as shown in
Further, the control unit 9 controls the slide drive motor 32 such that the obliquely conveying unit 26 moves to the retracting position Pe after a predetermined count from the time when the pre-registration sensor 103 is turned ON (STEP S10). Further, the control unit 9 pivots the reference member 20 by the angle adjustment motor 31 such that the angle β becomes equal to 0 degree (STEP S11). To be noted, it is acceptable to perform STEPS S10 and S11 in parallel with or earlier than STEPS S8 and S9.
Then, the control unit 9 judges whether or not the printing on the second surface is necessary (STEP S12). In a case where the printing on the second surface is not necessary (STEP S12: NO), that is, in a case of a simplex printing job, the control unit 9 ends the processing.
In a case of a duplex printing job in which the printing on the second surface is necessary (STEP S12: YES), in accordance with equations (8) to (10), the control unit 9 calculates a rotational angle γ, the standby position Pw, and the retracting position Pe, which are used when the sheet S on whose first surface the image has been formed returns to the skew correction unit 55. Then, the control unit 9 stores these in the memory 106 (STEP S13), and returns to STEP S6.
While the control unit 9 executes STEPS S6 to S11 based on the rotational angle γ, the standby position Pw, and the retracting position Pe stored in the memory 106, since the STEPS S6 to S11 at the time of printing on the second surface are similar to the descriptions at the time of printing on the first surface described above, descriptions will be omitted herein. Since, after the STEPS S6 to S11 at the time of printing on the second surface were ended, the printing on the second surface has been already completed at STEP S12, STEP S12 becomes NO, and the control unit 9 ends the processing.
To be noted, the skew correction control described above is performed on each sheet of the job, and, for example, in a case where the sheet bundle is formed in the post-processing apparatus 600, the skew correction control is performed on each sheet constituting the sheet bundle. That is, in a case where the post-processing reference edge does not match the abutment reference edge Es, the processing of STEPS S6 to S11 is performed on each sheet constituting the sheet bundle.
As described above, the skew correction control of this embodiment includes a first mode including STEPS S6 to S11 and a second mode including STEPS S14 to S15. The first mode is a mode in which the reference member 20 is moved such that the angle β becomes 90 degrees minus a before the sheet S has reached the abutment surface 20a or in a state where the sheet S is abutted against the abutment surface 20a. The second mode is a mode in which the reference member 20 is positioned such that the abutment surface 20a becomes parallel to the conveyance direction F before the sheet S has reached the abutment surface 20a or in a state where the sheet S is abutted against the abutment surface 20a.
As described above, by this embodiment, even in the case where the post-processing reference edge does not match the abutment reference edge Es, the skew correction control is performed such that the non-reference edge En becomes parallel to the width direction W. Since, in this state, the image is transferred onto the sheet S at the secondary transfer nip T2, the position of the image formed on the sheet S does not vary with respect to the non-reference edge En. Therefore, if the post-processing such as the stapling process is performed with reference to the non-reference edge En in the post-processing apparatus 600, there is not a variation of the image in the sheet bundle, so that it is possible to improve the quality of the deliverables.
Further, since the skew correction unit 55 employs an obliquely conveying registration method, it is possible to improve productivity, and also possible to perform the skew correction on various media such as thin paper and cardboard. Further, since the image forming position in the image forming unit 513 is fixed regardless of the position of the post-processing reference edge, it is possible to improve the productivity.
To be noted, while, in this embodiment, the skew correction unit 55 is treated as the sheet conveyance apparatus, it is acceptable to consider the image forming apparatus 100 including the skew correction unit 55 and the image forming unit 513 as the sheet conveyance apparatus. Further, it is acceptable to consider the image forming system 1 including the image forming apparatus 100 and the post-processing apparatus 600 as the sheet conveyance apparatus.
To be noted, while, in this embodiment, the non-reference edge En which becomes the post-processing reference edge is assumed to be the downstream edge in the conveyance direction F of the sheet S, namely the leading edge of the sheet S, it is not limited to this. For example, it is acceptable to treat an upstream edge in the conveyance direction F of the sheet S, namely the trailing edge Er (refer to
Further, it is acceptable to configure such that a user is able to arbitrarily choose the leading or trailing edge of the sheet for the post-processing reference edge. For example, it is acceptable to configure such that it is possible to choose the leading or trailing edge of the sheet for the post-processing reference edge by an operation panel of the image forming apparatus 100, an external personal computer (PC), and the like. Further, it is acceptable to configure such that the leading and trailing edges of the sheet chosen for the post-processing reference edge are automatically switched in the image forming apparatus 100 in accordance with the post-processing reference edge chosen by the post-processing apparatus 600.
Further, while, in this embodiment, whether or not the post-processing reference edge matches the abutment reference edge Es is automatically judged from the job input information, it is not limited to this. For example, it is acceptable that the user chooses whether or not the post-processing reference edge matches the abutment reference edge Es. Further, even in the case where the post-processing reference edge does not match the abutment reference edge Es, it is acceptable to configure such that, while not performing the control of STEPS S6 to S13 in
Further, in any of the embodiments described above, the descriptions are provided by using the image forming apparatus 100 of the electrophotographic system, this disclosure is not limited to this. For example, it is possible to apply this disclosure to an image forming apparatus of an ink jet system which forms the image on the sheet by ejecting a liquid ink through a nozzle. Further, the image forming apparatus 100 is not limited to a printer, but includes a copier, a facsimile, a multifunction machine, and the like.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
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 such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No.2021-117930, filed Jul. 16, 2021, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-117930 | Jul 2021 | JP | national |
