JP2021138464A - Image forming device - Google Patents

Abstract

To provide an image forming device capable of accelerating a speed in sorting a position of sheets mounted on a sheet discharging part in a sheet width direction to improve productivity in printing.SOLUTION: The image forming device includes a transferring part 5, a fixing part 40, a conveyance position adjustment mechanism 50, and a control part; the conveyance position adjustment mechanism 50 is arranged at an upstream side of the transferring part 5 in a sheet conveyance direction Dc to correct skew of a sheet S and change a conveyance position of the sheet S in a sheet width direction Dw orthogonal to the sheet conveyance direction Dc while conveying the sheet S; the control part controls the conveyance position adjustment mechanism 50 to be capable of achieving a sort conveyance mode of changing the conveyance position of the sheet S in the sheet width direction Dw by predetermined job unit, part unit or page unit alternately to a first position P1 at one end part side in the sheet width direction Dw and a second position P2 at the other end part side.SELECTED DRAWING: Figure 7

Description

The present invention relates to an image forming apparatus.

An image equipped with a sorting function that changes the position in the paper width direction orthogonal to the transport direction of the paper loaded in the discharge tray when the paper after image formation is discharged to the discharge tray outside the device and loaded. Forming devices and post-processing devices for image forming devices are known. An example of such a device is disclosed in Patent Document 1.

The sheet post-processing apparatus of the conventional image forming apparatus disclosed in Patent Document 1 includes a mounting table on which a copy sheet (paper) after image formation is temporarily placed and a stacker on which the copy sheet is finally loaded. It is equipped with a tray. The copy sheet is aligned in the paper transport direction by the backing plate and aligned in the paper width direction by the width adjusting member on the mounting table. When a plurality of copies of copy sheets are loaded on the stacker tray, the sheet post-processing apparatus can move the copy sheets in the paper width direction and load them in units of copies by the width adjusting member. For example, the odd-numbered portion can be loaded on one side in the paper width direction, and the even-numbered portion can be loaded on the other side in the paper width direction.

Japanese Unexamined Patent Publication No. 2-23150

However, in the above-mentioned prior art, the paper after image formation is finally ejected, and the paper is sorted (sorted) at the paper ejection portion including the stacker tray to be loaded. Therefore, the paper is sorted. The problem is that it takes a lot of time to complete loading on the tray. As a result, there is a concern that the productivity related to printing of the image forming apparatus may decrease.

The present invention has been made in view of the above points, and when sorting (sorting) for changing the position of the image-formed paper loaded on the paper ejection unit in the paper width direction, the speed is increased and printing is performed. It is an object of the present invention to provide an image forming apparatus capable of improving the productivity of the above.

In order to solve the above problems, the image forming apparatus of the present invention includes a transfer unit, a fixing unit, a transport position adjusting mechanism, and a control unit. The transfer unit transfers the toner image formed on the surface of the image carrier to the paper. The fixing portion is arranged on the downstream side in the paper transport direction with respect to the transfer portion, and the toner image is fixed to the paper by heating and pressurizing the paper on which the toner image is transferred by the transfer portion. The transport position adjusting mechanism is arranged on the upstream side of the paper transport direction with respect to the transfer unit, and while transporting the paper, corrects the skew of the paper and changes the paper transport position in the paper width direction orthogonal to the paper transport direction. And do. The control unit controls the transfer unit, the fixing unit, and the transport position adjusting mechanism. The control unit controls the transport position adjusting mechanism, and sets the transport position of the paper in the paper width direction in a predetermined job unit, copy unit, or page unit at the first position and the other end on the one end side in the paper width direction. It is possible to execute a sort transfer mode that alternately changes to the second position on the side.

According to the configuration of the present invention, it is possible to correct the skew of the paper and change the transport position of the paper in the paper width direction while transporting the paper on the upstream side in the paper transport direction with respect to the transfer unit. can. As a result, sorting (sorting) in the width direction of the paper after image formation can be efficiently performed. Therefore, when sorting the paper, it is possible to increase the speed and improve the productivity related to printing.

It is sectional drawing which shows the schematic structure of the image forming apparatus of embodiment of this invention. It is a block diagram which shows the schematic structure of the image forming apparatus of FIG. It is a top view of the transport position adjusting mechanism of the image forming apparatus of FIG. It is a side view of the transport position adjusting mechanism of FIG. It is a schematic plan view which shows the state of the skew correction and the position deviation correction by the transport position adjustment mechanism of FIG. It is a flowchart which shows Example 1 of the process of the sort transfer mode by the transfer position adjustment mechanism of FIG. FIG. 3 is a schematic plan view showing a state in which the paper transport position is changed to the first position by the transport position adjusting mechanism of FIG. FIG. 3 is a schematic plan view showing a state in which the paper transport position is changed to the second position by the transport position adjusting mechanism of FIG. It is a schematic plan view which shows the relationship between the paper transport position and the toner image formation position. It is a flowchart which shows Example 2 of the process of the sort transfer mode by the transfer position adjustment mechanism of FIG. It is a flowchart which shows Example 3 of the process of the sort transfer mode by the transfer position adjustment mechanism of FIG. FIG. 3 is a schematic plan view showing a state (Example 4) in which the paper transport position is slightly changed at the second position by the transport position adjusting mechanism of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following contents.

FIG. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus 1. FIG. 2 is a block diagram showing a schematic configuration of the image forming apparatus 1 of FIG. An example of the image forming apparatus 1 of the present embodiment is a so-called printer that receives image data related to a print job and a print command from an external computer and executes printing.

As shown in FIGS. 1 and 2, the image forming apparatus 1 includes a paper feeding unit 2, a paper conveying unit 3, an exposure unit 20, an image forming unit 30, a transfer unit 5, a fixing unit 40, a paper ejection unit 7, and a control unit. 10 and storage unit 11 are included.

The paper feeding unit 2 accommodates a plurality of sheets S, and separates and feeds the sheets S one by one at the time of printing. The paper transport unit 3 conveys the paper S fed from the paper feed unit 2 to the transfer unit 5 and the fixing unit 40, and further discharges the fixed paper S from the paper ejection port 3a to the paper ejection unit 7. The exposure unit 20 irradiates the image forming unit 30 with a laser beam controlled based on the image data.

The image forming unit 30 includes a photoconductor drum 31. The photoconductor drum 31 is an image carrier having a photosensitive layer formed on its surface and rotatably supported in a predetermined direction (clockwise in FIG. 1). The image forming unit 30 further includes a charging unit 32, a developing unit 33, and a cleaning unit 34 around the photoconductor drum 31 along the rotation direction thereof. The transfer unit 5 is arranged between the developing unit 33 and the cleaning unit 34.

The charging unit 32 charges the surface of the photoconductor drum 31 to a predetermined potential by, for example, corona discharge. The exposure unit 20 exposes the surface of the photoconductor drum 31 charged by the charging unit 32 by irradiating the laser beam to form an electrostatic latent image. The developing unit 33 attaches toner to the electrostatic latent image formed on the surface of the photoconductor drum 31 to form a toner image.

The transfer unit 5 is arranged below the image forming unit 30. The transfer unit 5 is arranged on the upstream side of the paper transport unit 3 in the paper transport direction Dc with respect to the fixing portion 40. The transfer unit 5 transfers the toner image formed on the surface of the photoconductor drum 31 by the image forming unit 30 onto the paper S. The cleaning unit 34 removes toner and the like remaining on the surface of the photoconductor drum 31 after transfer for cleaning.

The fixing section 40 is arranged on the downstream side of the paper transport section 3 in the paper transport direction Dc with respect to the image forming section 30 and the transfer section 5. The fixing unit 40 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is transferred by the transfer unit 5. The fixing unit 40 includes a fixing roller 41, a pressure roller 42, and a heating unit 43.

The fixing roller 41 and the pressure roller 42 are each formed in a cylindrical shape, and are arranged so that their peripheral surfaces face each other with the paper transport portion 3 sandwiched from above and below. The rotation axes of the fixing roller 41 and the pressure roller 42 extend along the paper width direction (paper surface depth direction in FIG. 1) orthogonal to the transport direction Dc of the paper S. At least one of the fixing roller 41 and the pressure roller 42 may be formed of a belt.

The fixing roller 41 is powered by a motor (not shown) and can rotate clockwise in FIG. 1 along the transport direction Dc of the paper S. The pressure roller 42 is powered by a motor (not shown) and can rotate counterclockwise in FIG. 1 along the transport direction Dc of the paper S. The outer peripheral surface of the pressure roller 42 presses and contacts the outer peripheral surface of the fixing roller 41 to form a fixing nip portion. The pressure roller 42 may be rotated according to the rotation of the fixing roller 41 by coming into contact with the fixing roller 41 without using a motor.

The heating unit 43 is arranged inside, for example, the fixing roller 41. The heating unit 43 is composed of, for example, a halogen lamp or a resistance heating element, and has a rod shape extending in parallel with the fixing roller 41 in the paper width direction. The heating unit 43 heats the fixing roller 41 from the inside of the fixing roller 41. As a result, the outer peripheral portion of the fixing roller 41 generates heat. The paper S on which the unfixed toner image is transferred is heated when passing through the fixing nip portion, and the toner is fixed on the surface thereof.

The control unit 10 includes a CPU (not shown), an image processing unit, other electronic circuits, and electronic components (not shown). The CPU controls the operation of each component provided in the image forming apparatus 1 based on the control program or data stored in the storage unit 11 to perform processing related to the function of the image forming apparatus 1. Each of the paper feed unit 2, the paper transport unit 3, the exposure unit 20, the image forming unit 30, the transfer unit 5, and the fixing unit 40 individually receives commands from the control unit 10 and prints on the paper S in conjunction with each other. ..

The storage unit 11 is composed of a combination of a non-volatile storage device such as a program ROM (Read Only Memory) and a data ROM (not shown) and a volatile storage device such as a RAM (Random Access Memory).

Further, the image forming apparatus 1 includes an edge detecting unit 12 and a transport position adjusting mechanism 50.

The edge detection unit 12 is arranged on the upstream side of the paper transport direction Dc with respect to the transfer unit 5. The edge detection unit 12 has, for example, a CIS (Contact Image Sensor) and a light source unit (both not shown). The CIS detects the edge position in the transport direction Dc and the width direction of the paper S based on the difference in light intensity between the portion where the light from the light source portion is incident and the portion where the light is blocked by the paper S.

The transport position adjusting mechanism 50 is arranged on the upstream side of the paper transport direction Dc with respect to the transfer unit 5 and on the downstream side of the edge detection unit 12. The transport position adjusting mechanism 50 corrects the skew (skew) of the paper S and changes the transport position of the paper S in the paper width direction while transporting the paper S.

Subsequently, the configuration of the transport position adjusting mechanism 50 will be described with reference to FIGS. 1, 4 and 5 in addition to FIGS. 1 and 2. FIG. 3 is a plan view of the transport position adjusting mechanism 50 of the image forming apparatus 1 of FIG. FIG. 4 is a side view of the transport position adjusting mechanism 50 of FIG. FIG. 5 is a schematic plan view showing a state of skew correction and misalignment correction by the transport position adjusting mechanism 50 of FIG.

As shown in FIGS. 3 and 4, the transport position adjusting mechanism 50 includes a transport roller pair 51, a roller holder 52, a carriage 53, a roller drive motor 54, a skew correction motor 55, a sort motor 56, and a reference. A position detection unit 57 is provided.

A plurality of transport roller pairs 51 are arranged in the paper width direction Dw, for example, four pairs are arranged in this embodiment. The transport roller pair 51 has a drive roller 511 and a driven roller 512. The drive roller 511 is fixed to the rotation shaft 513 and is rotated by the roller drive motor 54 via the rotation shaft 513. The driven roller 512 rotates according to the rotation of the driving roller 511 when the peripheral surface of the driven roller 512 comes into contact with the peripheral surface of the driving roller 511.

The roller holder 52 rotatably supports the rotating shaft 513 of the driving roller 511 and the rotating shaft 514 of the driven roller 512. One end side of the roller holder 52 in the paper width direction Dw (left end side in FIGS. 3 and 4, support end) is in the normal direction with respect to the transport surface of the paper S (paper depth direction in FIG. 3, top and bottom in FIG. A swing support shaft 521 extending in the direction) is provided. In the roller holder 52, the other end side (right end side in FIGS. 3 and 4 and the swing end) of the paper width direction Dw with respect to the carriage 53 can swing in the paper transport direction Dc with the swing support shaft 521 as the center. Is.

The carriage 53 supports the roller holder 52. The carriage 53 is movably supported by the front frame 1a and the back frame 1b of the image forming apparatus 1 in the paper width direction Dw.

The roller drive motor 54 is provided on the support end side (left end side in FIGS. 3 and 4) of the roller holder 52 in the paper width direction Dw. The roller drive motor 54 is connected to the rotation shaft 513 of the drive roller 511 via a plurality of gears. The roller drive motor 54 rotates and stops the rotating shaft 513. That is, the roller drive motor 54 rotates and stops the drive roller 511.

The skew correction motor 55 is connected to a rack 522 provided on the swing end side (right end side of FIGS. 3 and 4) of the roller holder 52 in the paper width direction Dw via a plurality of gears. The skew correction motor 55 swings the swing end side of the roller holder 52 in the paper width direction Dw in the paper transport direction Dc about the swing support shaft 521. That is, the skew correction motor 55 changes the inclination of the roller holder 52 with respect to the paper transport direction Dc. In other words, the skew correction motor 55 can tilt the transport roller pair 51 with respect to the paper transport direction Dc.

The sort motor 56 is connected to a rack tooth (not shown) formed on one end edge 53a of the carriage 53 in the paper transport direction Dc via a gear 56a. The sort motor 56 moves the carriage 53 in the paper width direction Dw. That is, the sort motor 56 can move the transport roller pair 51 in the paper width direction Dw.

As the roller drive motor 54, the skew correction motor 55, and the sort motor 56, for example, a stepping motor capable of accurately controlling the rotation direction and rotation amount (rotation angle) by pulse control is used.

The reference position detection unit 57 is provided on the front side frame 1a of the image forming apparatus 1. The reference position detection unit 57 includes, for example, an optical sensor arranged on the front frame 1a and having a light emitting unit and a light receiving unit, and a light shielding plate arranged on the roller holder 52 and appearing in the optical path of the optical sensor. The reference position detection unit 57 detects the reference position of the roller holder 52. The reference position of the roller holder 52 is the center of the paper transport section 3 in the paper width direction Dw, and the inclination with respect to the paper transport direction Dc is 0 (perpendicular to the paper transport direction Dc).

The transport position adjusting mechanism 50 having the above configuration corrects the skew (skew) of the paper S and changes the transport position of the paper S in the paper width direction Dw while transporting the paper S by the transport roller pair 51. be able to. The transfer position adjusting mechanism 50 corresponds to the correction of the skew of the paper S by inclining the transfer roller pair 51 with respect to the paper transfer direction Dc by the skew correction motor 55. The transport position adjusting mechanism 50 responds to the change of the transport position (correction of misalignment) of the paper S in the width direction Dw by moving the transport roller pair 51 in the paper width direction Dw by the sort motor 56.

For example, as shown in FIG. 5, when the paper S is tilted at an angle α with respect to the reference position P0 (the center of the paper width direction Dw) and causes a misalignment of the distance β, the edge detection unit 12 causes the paper S to shift. These inclinations and misalignments of the paper S are detected. The edge detection unit 12 detects the edge positions of the paper S in the transport direction Dc and the width direction Dw using CIS, and transmits the detection information to the control unit 10 (see FIG. 2).

The control unit 10 (see FIG. 2) derives a control signal of the transport position adjusting mechanism 50 based on the detection information detected by the edge detection unit 12 and transmits the control signal to the transport position adjusting mechanism 50. In the transport position adjusting mechanism 50, the sort motor 56 is controlled to correct the positional deviation of the distance β, and the skew correction motor 55 is controlled to correct the skew of the angle α. The sort motor 56 and the skew correction motor 55 are, for example, stepping motors, and the rotation direction and rotation amount (rotation angle) are controlled by pulse control.

In this way, the transport position adjusting mechanism 50 aligns the paper S with the reference position P0 (center of the paper width direction Dw) while transporting the paper S by the transport roller pair 51, and feeds the paper S toward the transfer unit 5 (see FIG. 5). The paper S is maintained at the center of the paper width direction Dw, and the paper transport unit 3 is transported to the fixing portion 40.

Then, the control unit 10 controls the transport position adjusting mechanism 50, and sorts (sorts) the paper S to be loaded on the paper discharge unit 7 so as to change the transport position of the paper S in the paper width direction Dw. Is feasible. In the sort transfer mode, the transfer position of the paper S in the paper width direction Dw is set to the first position P1 (see FIG. 7) on one end side of the paper width direction Dw in a predetermined job unit, copy unit, or page unit. Alternately change to the second position P2 (see FIG. 8) on the end side.

FIG. 6 is a flowchart showing the first embodiment of the process of the sort transfer mode by the transfer position adjusting mechanism 50 of FIG. FIG. 7 is a schematic plan view showing a state in which the transport position of the paper S is changed to the first position P1 by the transport position adjusting mechanism 50 of FIG. FIG. 8 is a schematic plan view showing a state in which the transport position of the paper S is changed to the second position P2 by the transport position adjusting mechanism 50 of FIG. FIG. 9 is a schematic plan view showing the relationship between the transport position of the paper S and the formation position of the toner image.

The control unit 10 starts the sort transfer mode based on the print command related to the print job (“sort transfer start” in FIG. 6). When the sort transfer mode is started, the control unit 10 determines whether or not the sort unit is an odd number of times (first, third, fifth, etc.) (step # 101 in FIG. 6). The sort unit is a job unit, a copy unit, or a page unit.

When the sort unit is an odd number of times (Yes in step # 101), as shown in FIG. 7, the control unit 10 sets the transport position of the paper S in the paper width direction Dw as the first position P1 and sets the transport position adjusting mechanism 50. Is controlled to move the paper S to the first position P1 (step # 102). When the sort unit is an even number (2nd, 4th, 6th ...) (No in step # 101), the control unit 10 sets the transport position of the paper S in the paper width direction Dw as shown in FIG. The second position P2 is set, and the transfer position adjusting mechanism 50 is controlled to move the paper S to the second position P2 (step # 103).

The control unit 10 controls the transport position adjusting mechanism 50, and while transporting the paper S by the transport roller pair 51, corrects the skew (skew) of the paper S and the transport position of the paper S in the paper width direction Dw. Sorting (sorting) to change is executed at the same time. That is, the skew correction and sorting of the paper S are performed at substantially the same timing without stopping the transport of the paper S along the transport direction Dc.

Subsequently, the control unit 10 controls the paper transport unit 3, the exposure unit 20, the image forming unit 30, the transfer unit 5, and the fixing unit 40 to execute printing (step # 104).

Next, the control unit 10 determines whether or not the transfer of all the sheets S is completed and the sort transfer mode is completed (step # 105). When the paper S to be conveyed still remains (No in step # 105), returning to step # 101, the control unit 10 determines whether or not the sort unit is an odd number of times. When the transfer of all the sheets S is completed and the sort transfer mode is completed (Yes in step # 105), the processing flow shown in FIG. 6 is completed.

According to the above configuration, while transporting the paper S on the upstream side of the paper transport direction Dc with respect to the transfer unit 5, the skew of the paper S is corrected, and the transport position of the paper S in the paper width direction Dw is changed. It can be performed. As a result, the paper S after the image formation can be efficiently sorted (sorted) in the paper width direction Dw. Therefore, when sorting the paper S, it is possible to increase the speed and improve the productivity related to printing.

Further, according to the above configuration, since the transport position of the paper S in the paper width direction Dw is changed, the paper S continuously passes through the same positions of the fixing roller 41 and the pressure roller 42 in the fixing portion 40. It can be avoided. As a result, it is possible to suppress the occurrence of wear on the surfaces of the fixing roller 41 and the pressure roller 42 due to the edges of the paper S repeatedly passing through the same location. Therefore, it is possible to improve the image quality and further extend the life of the fixing roller 41 and the pressure roller 42.

Further, since the transport position adjusting mechanism 50 includes the transport roller pair 51 having the above configuration, the skew correction motor 55, and the sort motor 56, the toner image is printed on the paper S immediately before the paper transport direction Dc with respect to the transfer unit 5. Immediately before the transfer to the paper S, the skew correction, sorting and misalignment correction of the paper S can be performed without stopping the transport of the paper S by the resist roller pair. As a result, it is possible to suppress the generation of collision noise of the paper S with respect to the resist roller pair. Further, during continuous printing, it is not necessary to consider suspending the transfer of the paper S at the position of the resist roller pair, and it is possible to improve the productivity related to printing.

The control unit 10 controls the exposure unit 20 when printing is executed in step # 104 of FIG. 6, and an electrostatic latent image of the surface of the photoconductor drum 31 based on the transport position of the paper S in the paper width direction Dw. The formation position of is changed to Dw in the paper width direction.

As shown in FIG. 9, the exposure unit 20 includes a light source 21, a collimator lens 22, a cylindrical lens 23, a polygon mirror 24, scanning lenses 25a and 25b, and a BD (Beam Detect) sensor 26. ..

The light source 21 includes, for example, a laser diode, and emits a light beam (laser beam) photomodulated based on an image signal. The collimator lens 22 makes the laser beam emitted from the light source 21 a substantially parallel luminous flux. The cylindrical lens 23 has a predetermined refractive power only in the sub-scanning direction of the laser beam. The parallel light beam that has passed through the collimator lens 22 and is incident on the cylindrical lens 23 remains as a parallel light beam in the main scanning cross section, converges and is emitted in the sub-scanning direction, and is emitted as a deflection surface (reflection surface) of the polygon mirror 24. ) Is imaged as a line image.

The polygon mirror 24 is a regular polygonal (regular pentagon in the present embodiment) rotating multifaceted mirror having a plurality of deflection surfaces (reflection surfaces) on its side surface. The polygon mirror 24 is rotated at a predetermined speed counterclockwise in FIG. 9 by a driving means (not shown) such as a motor. The scanning lenses 25a and 25b are lenses having an fθ characteristic. The laser beam deflected and reflected by the polygon mirror 24 passes through the scanning lenses 25a and 25b, is imaged on the photoconductor drum 31 with a spot diameter of a predetermined size, and is formed in the main scanning direction (from left to right in FIG. 9). ) Is scanned.

The BD sensor 26 is arranged on the scanning start side (left side in FIG. 9) outside the effective exposure region. The BD sensor 26 outputs a signal to the control unit 10 (see FIG. 2) according to the timing at which the laser beam is detected. As the BD sensor 26, various optical sensors such as a photodiode, a phototransistor, and a photoIC can be used.

When the transport position of the paper S in the paper width direction Dw is the reference position P0, the exposure start position of the photoconductor drum 31 by the exposure unit 20 is the position T0 in FIG.

When the transport position of the paper S in the paper width direction Dw is the first position P1, the transport position of the paper S in the paper width direction Dw moves to the scanning start side (left side in FIG. 9), so that the toner image on the paper S is displayed. The transfer position shifts to the scanning end side (right side in FIG. 9). Therefore, when the transport position of the paper S in the paper width direction Dw is changed to the first position P1, the light emission timing of the light source 21 is set according to the amount of movement of the paper width direction Dw from the reference position P0 to the first position P1. Make it faster. As a result, the detection timing of the laser beam by the BD sensor 26 becomes earlier, and the exposure start position (scanning start position) becomes the position T1.

When the transport position of the paper S in the paper width direction Dw is the second position P2, the transport position of the paper S in the paper width direction Dw moves to the scanning end side (right side in FIG. 9), so that the toner image on the paper S is displayed. The transfer position shifts to the scanning start side (left side in FIG. 9). Therefore, when the transport position of the paper S in the paper width direction Dw is changed to the second position P2, the light emission timing of the light source 21 is set according to the amount of movement of the paper width direction Dw from the reference position P0 to the second position P2. Slow down. As a result, the detection timing of the laser beam by the BD sensor 26 is delayed, and the exposure start position (scanning start position) becomes the position T2.

By changing the formation position of the electrostatic latent image on the surface of the photoconductor drum 31 to the paper width direction Dw based on the transport position of the paper S in the paper width direction Dw as in the above configuration, the paper width of the paper S is changed. Regardless of whether the transport position in the direction Dw is the reference position P0, the first position P1, or the second position P2, the toner image can be transferred to the center of the paper width direction Dw of the paper S to be transported.

FIG. 10 is a flowchart showing the second embodiment of the process of the sort transfer mode by the transfer position adjusting mechanism 50 of FIG.

When the sort transfer mode is started (“sort transfer start” in FIG. 10), the control unit 10 sets the transfer position in the paper width direction Dw at which the sheet S was conveyed at the end of the previous sort transfer mode to the first position. It is determined whether or not it was P1 (step # 201 in FIG. 10). Each time the sort transfer mode is executed, the transfer position in the paper width direction Dw at which the sheet S was last conveyed is stored in the storage unit 11 or the like.

When the transport position in the paper width direction Dw where the paper S was conveyed at the end of the previous sort transfer mode is the first position P1 (see FIG. 7) (Yes in step # 201), in the current sort transfer mode. When the sort unit is an odd number of times (first, third, fifth, etc.), the transport position of the paper S in the paper width direction Dw is set to the second position P2 (see FIG. 8) (step # 202). As a result, when the sort unit is an even number (2nd, 4th, 6th ...) In the sort transfer mode this time, the transfer position of the paper S in the paper width direction Dw becomes the first position P1 (see FIG. 7). .. Therefore, when the transport position in the paper width direction Dw at which the paper S was conveyed at the end of the previous sort transfer mode is the first position P1, in the current sort transfer mode, the odd-numbered transfer position of the sort unit is the first. The second position is P2, and the even-numbered transfer position is the first position P1.

When the transport position in the paper width direction Dw where the paper S was conveyed at the end of the previous sort transfer mode is the second position P2 (see FIG. 8) (No in step # 201), in the current sort transfer mode. When the sort unit is an odd number of times, the transport position of the paper S in the paper width direction Dw is set to the first position P1 (see FIG. 7) (step # 203). As a result, when the sort unit is an even number in the current sort transfer mode, the transfer position of the paper S in the paper width direction Dw is the second position P2 (see FIG. 8). Therefore, when the transport position in the paper width direction Dw at which the paper S was conveyed at the end of the previous sort transfer mode is the second position P2, in the current sort transfer mode, the odd-numbered transfer position of the sort unit is the second position. The first position is P1, and the even-numbered transfer position is the second position P2.

Subsequently, the control unit 10 determines whether or not the sort unit is an odd number of times (step # 204). The sort unit is a job unit, a copy unit, or a page unit.

When the sort unit is the odd-numbered times (Yes in step # 204), the control unit 10 sets the conveying position of the paper S in the paper width direction Dw to the odd-numbered times conveying position, and controls the conveying position adjusting mechanism 50 to transfer the paper S. Move to the odd-numbered transport position (step # 205). When the sort unit is an even-numbered number (No in step # 204), the control unit 10 sets the transport position of the paper S in the paper width direction Dw to the even-numbered transport position, and controls the transport position adjusting mechanism 50 to control the paper S. Move to the even-numbered transport position (step # 206).

Subsequently, the control unit 10 executes printing (step # 207).

Next, the control unit 10 determines whether or not the transfer of all the sheets S is completed and the sort transfer mode is completed (step # 208). When the paper S to be conveyed still remains (No in step # 208), returning to step # 204, the control unit 10 determines whether or not the sort unit is an odd number of times.

When the transfer of all the sheets S is completed and the sort transfer mode is completed (Yes in step # 208), the control unit 10 selects the sheet width direction Dw in which the sheets S are conveyed at the end of the current sort transfer mode. The transport position is stored in the storage unit 11 or the like (step # 209). Then, the processing flow shown in FIG. 10 is completed.

As described above, when the control unit 10 starts the sort transfer mode, the transfer position in the paper width direction Dw different from the transfer position in the paper width direction Dw in which the paper S was conveyed at the end of the previous sort transfer mode. The transfer of the paper S is started from. According to this configuration, the transport position of the paper S in the paper width direction Dw can be alternately changed to the first position P1 and the second position P2 across the front and rear print jobs. That is, it is possible to avoid that the first sort unit is always one of the first position P1 and the second position P2, and the last of the previous print job and the first of the next print job are sorted. It is possible to prevent the positions from overlapping. Further, it is possible to prevent the fixing roller 41 and the pressure roller 42 from being severely worn at any one of the first position P1 and the second position P2.

FIG. 11 is a flowchart showing the third embodiment of the process of the sort transfer mode by the transfer position adjusting mechanism 50 of FIG.

When the sort transfer mode is started (“sort transfer start” in FIG. 11), the control unit 10 determines that the cumulative number of sheets of paper S at the first position P1 is larger than the cumulative number of sheets of paper S at the second position P2. It is determined whether or not there are many (step # 301 in FIG. 11).

The image forming apparatus 1 includes a counting unit 13 shown in FIG. The counting unit 13 counts the cumulative number of sheets of paper S conveyed at each of the first position P1 and the second position P2. Each time the paper S is conveyed in the sort transfer mode, the cumulative number of sheets of paper S at the first position P1 and the cumulative number of sheets of paper S at the second position P2, which are counted by the counting unit 13, are stored in the storage unit. It is sequentially stored in 11 mag.

When the cumulative number of sheets of paper S at the first position P1 is larger than the cumulative number of sheets of paper S at the second position P2 (Yes in step # 301), the sort unit is an odd number of times (first time) in the current sort transfer mode. At the third, fifth, etc.), the transport position of the paper S in the paper width direction Dw is set to the second position P2 (see FIG. 8) (step # 302). As a result, when the sort unit is an even number (2nd, 4th, 6th ...) In the sort transfer mode this time, the transfer position of the paper S in the paper width direction Dw becomes the first position P1 (see FIG. 7). ..

When the cumulative number of sheets of paper S in the first position P1 is less than the cumulative number of sheets of paper S in the second position P2 (No in step # 301), when the sort unit is an odd number in the current sort transfer mode, The transport position of the paper S in the paper width direction Dw is set to the first position P1 (see FIG. 7) (step # 303). As a result, when the sort unit is an even number in the current sort transfer mode, the transfer position of the paper S in the paper width direction Dw is the second position P2 (see FIG. 8).

Subsequently, the control unit 10 determines whether or not the sort unit is an odd number of times (step # 304). The sort unit is a job unit, a copy unit, or a page unit.

When the sort unit is the odd-numbered times (Yes in step # 304), the control unit 10 sets the conveying position of the paper S in the paper width direction Dw to the odd-numbered times conveying position, and controls the conveying position adjusting mechanism 50 to transfer the paper S. Move to the odd-numbered transport position (step # 305). When the sort unit is an even-numbered number (No in step # 304), the control unit 10 sets the transport position of the paper S in the paper width direction Dw to the even-numbered transport position, and controls the transport position adjusting mechanism 50 to control the paper S. It is moved to the even-numbered transfer position (step # 306).

Subsequently, the control unit 10 executes printing (step # 307). Then, the counting unit 13 counts the cumulative number of sheets of paper S transported at each of the first position P1 and the second position P2, and the cumulative number of sheets transported is stored in the storage unit 11 or the like (step # 308). ).

Next, the control unit 10 determines whether or not the transfer of all the sheets S is completed and the sort transfer mode is completed (step # 309). When the paper S to be conveyed still remains (No in step # 309), returning to step # 304, the control unit 10 determines whether or not the sort unit is an odd number of times. When the transfer of all the sheets S is completed and the sort transfer mode is completed (Yes in step # 309), the processing flow shown in FIG. 11 is completed.

As described above, when the sort transfer mode is started, the control unit 10 starts the transfer of the paper S from the transfer position in the paper width direction Dw where the cumulative number of sheets to be transferred is small. According to this configuration, at the first position P1 and the second position P2 of the transport position of the paper S in the paper width direction Dw, the number of paper S to be conveyed can be added up and brought closer to each other. It is possible to make the degree of wear of the first position P1 and the second position P2 of the fixing roller 41 and the pressure roller 42 substantially equal.

FIG. 12 is a schematic plan view showing a state (Example 4) in which the transport position of the paper S is slightly changed at the second position P2 by the transport position adjusting mechanism 50 of FIG. As shown in FIG. 12, the control unit 10 transports the paper S at the second position P2 of the transport position in the paper width direction Dw of the paper S, for example, in a predetermined job unit, copy unit, or page unit. The transport position in the paper width direction Dw is sequentially changed by a predetermined amount within the second range R2 including the second position P2.

For example, when the sort unit is a job unit and the transport position of the paper S in the paper width direction Dw is the second position P2 in a certain job, the control unit 10 is in page units and the transport position in the paper width direction Dw. Is sequentially changed by a predetermined amount within the second range R2. For example, as shown in FIG. 12, a second range R2 in a predetermined paper width direction Dw including the second position P2 is preset.

Then, the control unit 10 conveys the paper S on the first page at the second position P2 with respect to the second position P2, and conveys the paper S on the second page at the position P22. The position P22 is slightly deviated from the second position P2 in the paper width direction Dw. Further, the paper S on the third and subsequent pages is also conveyed at a position slightly deviated from the second position P2 and the position P22 in the paper width direction Dw.

Here, the case where the transport position of the paper S is the second position P2 has been described as an example, but the same applies to the case where the transport position of the paper S is the first position P1. For example, as shown in FIG. 12, a first range R1 in a predetermined paper width direction Dw including the first position P1 (see FIG. 7) is preset. That is, when the paper S is conveyed at each of the first position P1 and the second position P2, the control unit sets the transfer position in the paper width direction Dw in a predetermined job unit, copy unit, or page unit. It is sequentially changed by a predetermined amount in the first range R1 including the first position P1 or in the second range R2 including the second position P2.

According to the above configuration, only specific portions of the fixing roller 41 and the pressure roller 42 are worn at each of the first position P1 and the second position P2 of the transport position of the paper S in the paper width direction Dw. It is possible to suppress this.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the gist of the invention.

For example, in the above embodiment, the image forming apparatus 1 is an image forming apparatus for monochrome printing that forms a monochrome image, but the present invention is not limited to such a model, and an image for color printing is used. It may be a forming device.

The present invention can be used in an image forming apparatus.

1 Image forming device 5 Transfer unit 10 Control unit 12 Edge detection unit 13 Counting unit 20 Exposure unit 30 Image forming unit 31 Photoreceptor drum (image carrier)
40 Fixing part 50 Transfer position adjustment mechanism 51 Transfer roller vs. 54 Roller drive motor 55 Skew correction motor 56 Sort motor Dc Paper transfer direction Dw Paper width direction P1 1st position P2 2nd position R1 1st range R2 2nd range S paper

Claims (6)

A transfer unit that transfers the toner image formed on the surface of the image carrier to paper, and
A fixing portion that is arranged on the downstream side in the paper transport direction with respect to the transfer portion and that fixes the toner image on the paper by heating and pressurizing the paper on which the toner image is transferred by the transfer portion.
It is arranged on the upstream side in the paper transport direction with respect to the transfer unit, and while transporting the paper, it corrects the skew of the paper and changes the paper transport position in the paper width direction orthogonal to the paper transport direction. Position adjustment mechanism and
A control unit that controls the transfer unit, the fixing unit, and the transport position adjusting mechanism, and
With
The control unit controls the transport position adjusting mechanism, and sets the transport position in the paper width direction as a first position on one end side in the paper width direction in a predetermined job unit, copy unit, or page unit. An image forming apparatus characterized in that a sort transfer mode that alternately changes to a second position on the other end side can be executed. When the control unit starts the sort transfer mode, the control unit transfers the paper from the transfer position in the paper width direction different from the transfer position in the paper width direction in which the paper was transferred at the end of the previous sort transfer mode. The image forming apparatus according to claim 1, wherein the image forming apparatus is started. A counting unit for counting the cumulative number of sheets of paper transported at each of the first position and the second position is provided.
The image forming apparatus according to claim 1, wherein when the sort transfer mode is started, the control unit starts the transfer of paper from the transfer position in the paper width direction in which the cumulative number of sheets to be transferred is small. When the paper is conveyed at each of the first position and the second position, the control unit sets the conveyed position in the paper width direction in a predetermined job unit, copy unit, or page unit. The image forming apparatus according to claim 2 or 3, wherein the image forming apparatus is sequentially changed by a predetermined amount within the first range including the position or within the second range including the second position. The transport position adjusting mechanism is
A transport roller pair that corrects the skew of the paper and changes the transport position in the paper width direction while transporting the paper.
A skew correction motor that tilts the transport roller pair with respect to the paper transport direction,
A sort motor that moves the transport roller pair in the paper width direction,
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is provided. An exposed portion that exposes the surface of the charged image carrier to form an electrostatic latent image is provided.
The control unit controls the exposed unit and changes the formation position of the electrostatic latent image on the surface of the image carrier in the paper width direction based on the transport position in the paper width direction. The image forming apparatus according to any one of claims 1 to 5.

Images