JP6551189B2 - Image forming apparatus and control program therefor - Google Patents

Description

  The present invention relates to an image forming apparatus and its control program.

  Generally, an image forming apparatus such as a printer includes a paper discharge tray (including a stacker or the like) for stacking sheets on which an image has been formed. Since the sheet discharge tray has a structure inclined along the sheet conveyance direction, the trailing edge of the sheet to be discharged abuts against the reference surface (for example, the side wall of the image forming apparatus) by gravity to align the sheets. Sex is secured.

  Further, there is also a technique for correcting the skew or distortion of the sheet (hereinafter, also referred to as "skew" although hereinafter referred to as "skew") prior to image formation, as well as at the time of paper discharge. For example, Patent Document 1 discloses a technique for correcting the bending of a sheet by abutting the leading end of the sheet against a registration roller.

  In any case, when using special paper having non-linear ends (including tab sheets, envelopes, etc.), the direction of the non-linear ends must be carefully noted. For example, at the time of paper discharge, the consistency can not be ensured unless the non-linear end portion is discharged toward the leading side in the transport direction. Further, at the time of bending correction, if the end portion that is not linear is not directed toward the end in the transport direction, the linear end cannot be abutted against the registration roller, and the bending of the special paper cannot be corrected with high accuracy.

JP 2005-31024 A

  Due to the above circumstances, when performing single-sided printing using special paper, bend the edges that are not linear toward the end in the transport direction, and then reverse the front and back of the special paper to create straight lines. It is necessary to control the discharge so that the end portion that is not shaped is directed toward the leading side in the transport direction.

  In the case of face-down printing, there is no problem with the above control, but in the case of face-up printing in which the front and back sides of the special paper are never reversed.

  In other words, with emphasis on the accuracy of bending correction, if the edge that is not linear is corrected toward the end in the transport direction, the end that is not linear remains at the end in the transport direction when discharging, A non-straight end is in contact with the reference surface of the paper discharge tray, and it becomes impossible to ensure consistency during paper discharge. On the contrary, focusing on the consistency at the time of paper discharge and correcting the bending of the non-linear end toward the leading side in the transport direction, the non-linear end will abut against the registration roller, It becomes impossible to correct the bend accurately.

  In addition, when performing double-sided printing using special paper, Patent Document 1 also discloses a technology for correcting the bending by striking the leading end or the rear end of the special paper at a place different from the registration roller. However, the cited document 1 discloses only an example in which the distance to which the special paper is transported to the image forming position after the correction of the bend is long, or an example in which the bend correction is performed along the curved path. There is a possibility that the paper may be bent.

  The present invention has been made in view of the above circumstances. That is, when printing using special paper, regardless of the printing method, the consistency at the time of paper discharge is ensured, and the image formation which can prevent the occurrence of the bending after the bending correction without reducing the accuracy of the bending correction An object is to provide a device or the like. Here, the printing method includes single-sided printing, double-sided printing, face-up printing, and face-down printing.

  (1) A sheet storage unit for storing a sheet, an image forming unit for forming an image on the sheet fed from the sheet storage unit, and the sheet on which an image is formed on the first surface by the image forming unit A sheet reversing section for reversing the front and back and enabling formation of an image by the image forming section on the second surface, a pair of tip resist rollers disposed at a position for delivering the sheet to the image forming section, and the sheet storage section A straight conveyance route on the image forming unit side and at the upstream side of the pair of leading end resist rollers with respect to the position where the conveyance route from the image forming unit to the image forming unit and the conveyance route of the sheet reversing unit merge When the rear end registration roller pair disposed in the inside and one end on the front end side of the sheet in the transport direction are linear, the front end of the sheet is abutted against the front end resist roller pair to perform bending correction. Paper When one end on the leading end side in the feed direction is not linear, the conveyance direction of the sheet is reversed, and the correction control unit performs bending correction by abutting the rear end of the sheet against the pair of rear end registration rollers; An image forming apparatus comprising: a paper discharge control unit that discharges the paper in a state where one end of the paper is directed toward the rear end side in the transport direction.

  (2) When the correction control unit abuts the rear end of the sheet against the rear end registration roller pair to perform bending correction, the correction control unit abuts the rear end of the sheet against the rear end registration roller pair The sheet is nipped by the pair of rear end registration rollers and conveyed by a predetermined amount without changing the conveying direction, and then the sheet is conveyed in the direction of the image forming section by reversing the conveying direction of the sheet. The image forming apparatus according to (1).

  (3) The correction control unit bends the rear end of the sheet against the rear end registration roller pair in comparison with the case where the front end of the sheet is abutted against the front end registration roller pair to perform bending correction The image forming apparatus according to (1) or (2), wherein when the correction is performed, the conveyance speed of the sheet is increased.

  (4) The rear end registration roller pair is selected according to the length of the sheet in the conveyance direction from among the plurality of conveyance roller pairs disposed on the upstream side of the front end registration roller pair. The image forming apparatus according to any one of (1) to (3).

  (5) The correction control unit is configured to, while the rear end of the sheet is in contact with the rear end registration roller pair, the rear end of the transport roller pair disposed downstream of the rear end registration roller pair The image forming apparatus according to (4), wherein a transport roller pair other than the transport roller pair used to control the abutment of the registration roller pair is separated.

  (6) The correction control unit, after abutting the sheet against the pair of rear end registration rollers, transports the sheet toward the image forming unit, the sheet being separated from the pair of conveyance rollers in the separated state The image forming apparatus according to (5), wherein the tip is sequentially returned to the pressure-bonded state from the pair of transport rollers through which the tip has passed.

  (7) The correction control unit, after abutting the sheet against the rear end registration roller pair, transfers the sheet of the transport roller pair in a separated state when the sheet is conveyed in the direction of the image forming unit. The image forming apparatus according to (6), wherein the pair of conveyance rollers that are not necessary for conveyance is maintained in a separated state.

  (8) Any of the above (4) to (7), wherein the plurality of transport roller pairs that can be selected as the leading end resist roller pair and the rear end resist roller pair have a higher transport force than other transport roller pairs. An image forming apparatus according to claim 1.

  (9) In the above (1) to (8), a retreat path is provided for retreating the front end side of the paper before the rear end of the paper is abutted against the pair of rear end registration rollers to perform bending correction. The image forming apparatus according to any one of the above.

  (10) The image forming unit includes a transfer roller pair and a fixing roller pair, and the correction control unit performs the transfer before the rear end of the sheet is abutted against the rear end resist roller pair to perform the bending correction. The image forming apparatus according to any one of the above (1) to (9), wherein the roller pair and the fixing roller pair are separated, and the leading end side of the sheet is retracted in the space generated by the separation.

  (11) The correction control unit performs bending correction when the leading edge of the sheet is abutted against the leading edge resist roller pair to perform bending correction, and the trailing end of the sheet abuts against the trailing edge registration roller pair to perform bending correction The image forming apparatus according to any one of the above (1) to (10), wherein the loop amount and abutment time of the sheet generated by abutment are made different depending on cases.

  (12) The input of information on the orientation of the sheet set in the sheet storage unit is received, and the non-linear end of the sheet is the front end side in the transport direction or the rear end side in the transport direction. The image forming apparatus according to any one of (1) to (11), further comprising: a setting unit that determines which of the leading end registration roller pair and the rear end registration roller pair is to be used for sheet bending correction.

  (13) With reference to the detection unit that detects the orientation of the sheet set in the sheet storage unit and the detection value obtained by the detection unit, whether the non-linear end of the sheet is on the leading end side in the transport direction The setting unit configured to determine which of the leading end registration roller pair and the trailing end registration roller pair is to be used for correcting the bending of the sheet depending on whether it is the rear end side in the conveyance direction; An image forming apparatus according to any one of (11) to (11).

  (14) The detection unit includes a plurality of sensors arranged side by side in the width direction of the sheet, and the setting unit is configured to contact the sheet storage unit based on a difference between detection values obtained from the sensors. The image forming apparatus according to (13), wherein it is determined whether the non-linear end of the set sheet is the front end side in the transport direction or the rear end side in the transport direction.

  (15) When single-sided printing and face-up printing are designated, and the non-linear end of the paper set in the paper container is on the rear end side in the transport direction, or single-sided printing and face-down printing are designated, The apparatus further comprises a notification unit that notifies that the orientation of the sheet should be changed when the non-linear end of the sheet set in the sheet storage unit is on the leading end side in the transport direction, The image forming apparatus according to any one of (14).

  (16) A sheet storage unit for storing sheets, an image forming unit for forming an image on the sheet fed from the sheet storage unit, and the sheet on which an image is formed on the first surface by the image forming unit A sheet reversing section for reversing the front and back and enabling formation of an image by the image forming section on the second surface, a pair of tip resist rollers disposed at a position for delivering the sheet to the image forming section, and the sheet storage section A straight conveyance route on the image forming unit side and at the upstream side of the pair of leading end resist rollers with respect to the position where the conveyance route from the image forming unit to the image forming unit and the conveyance route of the sheet reversing unit merge (A) when the one end on the front end side of the sheet in the conveyance direction is linear, the front end of the sheet is used as the front end resist roller pair; (B) reverse the conveyance direction of the sheet if the one end on the front side of the sheet in the conveyance direction is not linear, and reverse the rear end of the sheet; (C) the sheet subjected to bending correction by at least one of the step (a) and the step (b), and the linear end of the sheet is conveyed in the conveying direction; A control program for the image forming apparatus for executing a procedure of discharging paper in a state directed toward the end side.

  According to the present invention, the leading end resist roller pair and the trailing end resist roller pair are disposed in the vicinity of the image forming unit and in the linear conveyance path. Then, depending on whether or not one end on the leading end side of the sheet in the conveyance direction is linear, either the leading end registration roller pair or the trailing end registration roller pair is selected to perform bending correction. At the time of paper discharge, the paper is discharged in a state where one end of the linear shape faces the rear end side in the transport direction. As a result, when printing using special paper, regardless of the printing method, the consistency at the time of paper discharge can be ensured, the accuracy of the bending correction can not be reduced, and the generation of the bending after the bending correction can be prevented.

1 is a schematic configuration diagram of an image forming apparatus. It is the front view which expanded the conveyance path part in which curve amendment is performed. It is the top view which expanded the conveyance path part to which curvature amendment is performed. FIG. 2 is a block diagram showing an example of a functional configuration of the image forming apparatus. It is a flowchart of a setting process. 6 is a diagram illustrating an example of a notification screen indicating that the orientation of a sheet should be changed. FIG. It is a flowchart of the setting process for both sides. 10 is a flowchart of print control processing when single-sided printing and face-up printing are instructed. FIG. 10 is a diagram for explaining a trailing edge registration operation (first half) when the length in the sheet conveyance direction is short. FIG. 10 is a diagram for explaining a trailing edge registration operation (second half) when the length in the sheet conveyance direction is short. FIG. 10 is a diagram for explaining a trailing edge registration operation (first half) when the length in the sheet conveyance direction is long. FIG. 10 is a diagram for explaining a trailing edge registration operation (second half) when the length of a sheet in the conveyance direction is long. 6 is a flowchart of print control processing when single-sided printing and face-down printing are instructed. It is a figure for demonstrating tip resisting operation (the first half). It is a figure for demonstrating tip resisting operation (the second half). 7 is a flowchart of print control processing when double-sided printing is instructed. FIG. 6 is a diagram illustrating a sensor that automatically detects the orientation of a sheet.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

[Image forming apparatus 100]
FIG. 1 is a schematic configuration diagram of the image forming apparatus 100. FIG. 2 is an enlarged front view of the conveyance path portion where the bending correction is performed. FIG. 3 is an enlarged top view of a conveyance path portion where bending correction is performed. The schematic configuration of the image forming apparatus 100, particularly the hardware configuration, will be described below with reference to FIGS.

(1) Overall Configuration The image forming apparatus 100 according to the present embodiment is a printer having at least a function of forming an image on a sheet P, a copier, a facsimile, a multifunction peripheral (MFP: Multifunction Peripheral) or the like. In the present embodiment, as the paper P, special paper (including tab paper, envelope, etc.) having a non-linear end is used.

  As a specific hardware configuration, as illustrated in FIG. 1, the image forming apparatus 100 fixes the control unit 110, the touch panel unit 120, the sheet storage unit 130, the bending correction unit 140, the image forming unit 150, and The printer includes a unit 160, a sheet discharge unit 170, and a sheet reversing unit 180.

(1-1) Control unit 110
The control unit 110 controls the entire image forming apparatus 100. For example, the control unit 110 includes a central processing unit (CPU), a memory, and a storage.

  The CPU is a control circuit configured of a multi-core processor or the like that performs control of the above-described units and various arithmetic processing according to a program, and each function of the image forming apparatus 100 executes the corresponding program. It is exhibited by

  The memory is a high-speed accessible main storage device that temporarily stores programs and data as a work area. For the memory, for example, a DRAM (Dymmamic Random Access Memory), an SDRAM (Synchronous Dymamic Random Access Memory), an SRAM (Static Random Access Memory), etc. are adopted.

  The storage is a large-capacity auxiliary storage device that stores various programs including an operating system and various data. For the storage, for example, a hard disk, a solid state drive, a flash memory, a ROM, or the like is employed.

(1-2) Touch panel unit 120
The touch panel unit 120 includes a display unit such as a display and a transparent operation panel attached to the display surface side of the display unit. The touch panel unit 120 specifies a touch position corresponding to the XY coordinates of the image displayed on the display unit, converts the touch position into coordinates, and outputs the coordinate. The touch panel unit 120 is configured of a pressure-sensitive or electrostatic input detection element or the like.

(1-3) Paper storage unit 130
The paper storage unit 130 is a paper supply tray that stores the paper P. The sheet P is transferred from the sheet storage unit 130 via the bending correction unit 140 (via the points A, B, and C shown in FIG. 1) by driving of the sheet feeding roller etc. It is conveyed to the position of the pair 155.

(1-4) Bending corrector 140
As illustrated in FIGS. 2 and 3, the bending correction unit 140 includes a first transport roller pair 141, a second transport roller pair 142, a third transport roller pair 143, a fourth transport roller pair 144, and a tip registration And a roller pair 145.

  The first transport roller pair 141, the second transport roller pair 142, the third transport roller pair 143, and the fourth transport roller pair 144 are each composed of a pair of transport rollers. The sheet is conveyed in the direction of the roller pair 145. As shown in FIGS. 2 and 3, the first transport roller pair 141, the second transport roller pair 142, the third transport roller pair 143, and the fourth transport roller pair 144 are arranged in this order in the transport direction of the paper P. Ru.

  The leading end registration roller pair 145 is disposed at a position downstream of each of the conveyance roller pairs 141, 142, 143, and 144 at a position where the sheet P is sent out to the image forming unit 150. The front registration roller pair 145 includes a pair of registration rollers, and sends the paper P to the image forming unit 150 with the paper P interposed therebetween.

  The bending correction unit 140 configured as described above corrects the bending of the paper P. For example, when one end on the leading end side of the sheet P in the conveyance direction is linear, the leading end of the sheet P is abutted against the leading end registration roller pair 145 to perform bending correction. On the other hand, when one end on the front side in the transport direction of the paper P is not linear (there is a tab or the like), the transport direction of the paper P is reversed, and one of the transport roller pairs 141, 142, 143, 144 is The rear end of the sheet P is abutted to correct a bend. Hereinafter, one conveyance roller pair 141, 142, 143, 144 with which the sheet P is abutted at this time is referred to as a rear end registration roller pair.

  Further, when the rear end of the paper P is abutted to correct the bending, a retreat path for retracting the front end side of the paper P (a path between the point C and the point C ′ shown in FIGS. 1 and 2). Is provided.

  A detailed operation (hereinafter, referred to as “tip resist operation”) when the tip of the sheet P abuts against the tip resist roller pair 145 to perform a bend correction will be described later. Similarly, a detailed operation (hereinafter referred to as “rear end registration operation”) when the rear end of the sheet P is abutted against the rear end registration roller pair 141, 142, 143, 144 to perform bending correction will also be described later. .

(1-5) Image forming unit 150
Referring back to FIG. 1, the image forming unit 150 forms a toner image by an image forming process such as an electrophotographic method, and transfers the toner image to the sheet P. For example, the image forming unit 150 adopts a tandem system in which photosensitive drums independent for each of C (cyan), M (magenta), Y (yellow), and K (black) are used. The toner images of the respective colors formed on the photosensitive drums (C, M, Y, K) are sequentially transferred onto the intermediate transfer belt, and the toner images (colors) in which the layers of the respective colors (C, M, Y, K) are superimposed. Image) is formed on the intermediate transfer belt. Here, the intermediate transfer belt is an endless belt, which is wound around a plurality of rollers and supported so as to travel. Then, a toner image formed on the intermediate transfer belt is transferred onto the paper P by applying a bias having a polarity opposite to that of the toner to the transfer roller 155.

  However, the image forming unit 150 may adopt a rotary method instead of the tandem method as described above. Further, methods other than the electrophotographic method (ink jet method, impact method, thermal transfer method, etc.) may be adopted.

(1-6) Fixing unit 160
The fixing unit 160 includes a pair of fixing rollers, and fixes the toner image transferred onto the paper P on the paper P by heating. For example, the fixing unit 160 presses one fixing roller used as a heat source against the other fixing roller used as a pressure member. As a result, heat and pressure are applied to the sheet P at the fixing nip portion, and the toner image is fused and fixed.

(1-7) Paper Discharge Unit 170
The sheet discharge unit 170 is a sheet discharge tray on which the sheets P on which an image is formed are stacked. After passing through the fixing unit 160, the paper P is discharged to the paper discharge unit 170 via points D and E shown in FIG. Since the discharge tray has a structure that is inclined along the conveyance direction of the paper P, the trailing edge of the discharged paper abuts against the reference surface W due to gravity, and the consistency of the paper P is ensured. When the paper P on which the image is formed is reversed and discharged, the paper P is transported in the direction from the point D to the point F, and then the transport direction is reversed so that the point P to the point E. In this direction, the paper is discharged.

(1-8) Paper reversing unit 180
The sheet reversing unit 180 reverses the front and back of the sheet P on which the image is formed on the first side by the image forming unit 150, and enables the image forming unit 150 to form an image on the second side (that is, double-sided printing is possible). Do. For example, the sheet reversing unit 180 is configured of a conveyance path from the point F to the point B illustrated in FIG. 1. After the sheet P on which the image is formed on the first surface is transported from the point F to the point G, the transport direction is reversed, and the sheet P is transported from the point G to the point B via the point H.

  The image forming apparatus 100 having the above hardware configuration has a functional configuration as shown in FIG.

(2) Functional Configuration FIG. 4 is a block diagram showing an example of a functional configuration of the image forming apparatus 100. As shown in FIG. As illustrated in FIG. 4, the control unit 110 of the image forming apparatus 100 includes a setting unit 310, a correction control unit 320, a paper discharge control unit 330, and a notification unit 340.

(2-1) Setting unit 310
The setting unit 310 performs various settings related to printing based on user instructions.

  For example, the setting unit 310 determines which of single-sided printing and double-sided printing is used.

  Also, the setting unit 310 determines whether to print using face-up printing or face-up printing. Note that face-up printing refers to a printing method in which a surface on which an image is formed is discharged upward, and face-down printing refers to a printing method in which a surface on which an image is formed is discharged downward. Point to.

  Further, the setting unit 310 determines which of the leading end registration roller pair 145 and the trailing end registration roller pair 141, 142, 143, and 144 is used when correcting the bending of the sheet P.

  The user's instruction may be received from touch panel unit 120, or may be received from an external terminal (PC: Personal Computer or the like) in which driver software capable of controlling image forming apparatus 100 is installed.

(2-2) Correction control unit 320
The correction control unit 320 controls the bending correction performed on the paper P. For example, when one end of the leading end side of the sheet P in the conveyance direction is linear, the correction control unit 320 performs a leading end registration operation. On the other hand, when the leading end side of the sheet P in the transport direction is not linear, the correction control unit 320 performs the trailing end registration operation.

(2-3) Paper Discharge Control Unit 330
The paper discharge control unit 330 controls the paper P to be discharged. For example, the paper discharge control unit 330 discharges the paper P to the paper discharge unit 170 in a state where one end of the linear shape faces the rear end in the transport direction in order to ensure the consistency of the paper P at the time of paper discharge. . Specifically, when the rear end side of the sheet P conveyed from the fixing unit 160 in the transport direction is linear, the sheet discharge control unit 330 discharges the sheet P to the sheet discharge unit 170 without reversing the front and back of the sheet P. Control to print. On the other hand, when the rear end side of the sheet P conveyed from the fixing section 160 in the conveyance direction is not linear, the sheet ejection control section 330 controls the sheet P to be reversed before being ejected to the sheet ejection section 170. I do.

(2-4) Notification unit 340
If printing is performed with "specified setting content" and "the state of the sheet P set in the sheet storage unit 130", the notification unit 340 may not be able to ensure consistency at the time of discharge, When the correction accuracy decreases, the user is notified of the fact. For example, the notification unit 340 specifies the orientation of the paper P when single-sided printing and face-up printing are designated and the non-linear end of the paper P set in the paper storage unit 130 is the rear end side in the transport direction. Notify that it should be changed. Further, the notification unit 340 changes the orientation of the paper P even when single-sided printing and face-down printing are specified and the non-linear end of the paper P set in the paper storage unit 130 is the front end side in the transport direction. Notify you. The user who receives this notification can set the paper P in the proper orientation. In addition, as a notification method to a user, the method of displaying a text on the display part of the touch panel part 120 may be sufficient, and the method of outputting an audio | voice from a speaker may be sufficient.

  The setting unit 310, the correction control unit 320, the sheet discharge control unit 330, and the notification unit 340 are realized by the CPU reading out a program installed in the storage into a memory and executing the program. However, the present invention is not limited to this, and hardware such as ASIC (Application Specific Integrated Circuit) may be used.

[Operation of Image Forming Apparatus 100]
Next, characteristic operations of the image forming apparatus 100 according to the present embodiment will be described.

(1) Setting Process FIG. 5 is a flowchart of the setting process. The setting process is executed in the image forming apparatus 100.

  When the control unit 110 of the image forming apparatus 100 receives an instruction to start setting via the touch panel unit 120 from the user, the control unit 110 starts setting processing. However, the present invention is not limited to this, and the control unit 110 may start the setting process when a print job is received from an external terminal (PC or the like).

(Step S101)
When the setting process is started, the control unit 110 functions as the setting unit 310 and determines whether or not single-sided printing is designated.

  Specifically, when the control unit 110 receives an input for selecting single-sided printing from the user via the touch panel unit 120, the control unit 110 determines that single-sided printing is designated. On the other hand, when the control unit 110 receives an input for selecting double-sided printing from the user via the touch panel unit 120, the control unit 110 determines that single-sided printing is not designated. When the print job is accepted and the setting process is started, the control unit 110 may refer to the job ticket of the print job to determine whether single-sided printing is designated.

  And the control part 110 advances a process to step S102, when single-sided printing is designated (step S101: YES). On the other hand, if single-sided printing is not designated (step S101: NO), control unit 110 advances the process to step S108.

(Step S102)
The control unit 110 functions as the setting unit 310 and determines whether or not a special paper having a non-linear end is designated as the paper P used for printing.

  Specifically, when the control unit 110 receives an input for selecting a special sheet such as a tab sheet or an envelope from the user via the touch panel section 120, it determines that the special sheet is designated. On the other hand, when the control unit 110 receives an input for selecting a paper type other than special paper from the user via the touch panel unit 120, the control unit 110 determines that the special paper is not designated. When the print job is received and the setting process is started, the control unit 110 may determine whether the special sheet is designated by referring to the job ticket of the print job.

  When the special paper is designated (step S102: YES), the control unit 110 advances the process to step S103. On the other hand, when no special paper is designated (step S102: NO), control unit 110 advances the process to step S107.

(Step S103)
The control unit 110 functions as the setting unit 310, and determines whether face-up printing is designated.

  Specifically, when the control unit 110 receives an input for selecting face-up printing from the user via the touch panel unit 120, the control unit 110 determines that face-up printing is designated. On the other hand, when the control unit 110 receives an input for selecting face-down printing from the user via the touch panel unit 120, the control unit 110 determines that face-up printing is not specified. When the print job is received and the setting process is started, the control unit 110 may refer to the job ticket of the print job to determine whether face-up printing is designated.

  Then, when face-up printing is designated (step S103: YES), the control unit 110 advances the process to step S104. On the other hand, when face-up printing is not designated (step S103: NO), control unit 110 advances the process to step S106.

(Step S104)
The control unit 110 functions as the setting unit 310 and determines whether or not the non-linear end (for example, a tab) of the paper P set in the paper storage unit 130 is on the front end side in the paper feeding direction.

  Specifically, control unit 110 receives information on the orientation of sheet P set in sheet storage unit 130 from the user via touch panel unit 120, and makes a determination based on the information.

  Then, if the non-linear end of the sheet P set in the sheet storage unit 130 is the leading end side in the sheet feeding direction (step S104: YES), the control unit 110 advances the process to step S105.

  On the other hand, when the non-linear end of the sheet P set in the sheet storage section 130 is not the leading end side in the sheet feeding direction (step S104: NO), the control section 110 functions as the notification section 340. Notify that the orientation should be changed. FIG. 6 is a diagram illustrating an example of a notification screen indicating that the paper orientation should be changed. As shown in FIG. 6, the control unit 110 notifies by displaying a character string such as “Please change the paper orientation” on the display unit of the touch panel unit 120.

  After this notification, the control unit 110 stands by until the non-linear end of the sheet P set in the sheet storage unit 130 by the user is directed to the leading end side in the sheet feeding direction, and the processing is performed at step S105 at the directed timing. Advance.

(Step S105)
The control unit 110 functions as the setting unit 310, and the non-linear end of the sheet P set in the sheet storage unit 130 is the leading end side in the sheet feeding direction. , 142, 143, 144 are used.

  Thereafter, the control unit 110 ends the setting process.

(Step S106)
The control unit 110 functions as the setting unit 310 and determines whether the non-linear end of the paper P set in the paper storage unit 130 is on the rear end side in the paper feeding direction.

  Specifically, control unit 110 receives information on the orientation of sheet P set in sheet storage unit 130 from the user via touch panel unit 120, and makes a determination based on the information.

  Then, if the non-linear end of the sheet P set in the sheet storage section 130 is the rear end side in the sheet feeding direction (step S106: YES), the control section 110 advances the process to step S107.

  On the other hand, when the non-linear end of the sheet P set in the sheet storage section 130 is not the rear end side in the sheet feeding direction (step S106: NO), the control section 110 functions as the notification section 340. As shown in FIG. 6, the fact that the orientation of the paper P should be changed is notified.

  After this notification, the control unit 110 stands by until the non-linear end of the sheet P set in the sheet storage unit 130 by the user is directed to the rear end side in the sheet feeding direction, and the processing is performed at the directed timing S107. Advance to

(Step S107)
The control unit 110 functions as the setting unit 310, and the non-linear end of the sheet P set in the sheet storage unit 130 is the rear end side in the sheet feeding direction. Decide to use.

  Thereafter, the control unit 110 ends the setting process.

(Step S108)
When the process proceeds from step S101 to step S108, the control unit 110 executes a setting process for both sides described later.

  The above setting process is performed in the image forming apparatus 100. As a result, depending on whether the one end of the sheet P set in the sheet storage portion 130 is not the linear end is the leading end side or the trailing end side in the transport direction, the pair of leading end registration rollers 145 and the pair of trailing ends registration rollers 141, 142, 143, 144 can be determined.

(2) Double-Sided Setting Process FIG. 7 is a flowchart of the double-sided setting process. Note that the duplex setting process is executed in the image forming apparatus 100.

  The control unit 110 of the image forming apparatus 100 starts the duplex setting process when the process proceeds to step S108 in the above setting process.

(Step S201)
When the double-sided setting process is started, the control unit 110 functions as the setting unit 310, and executes the same process as step S102, whereby a special paper having an end portion that is not linear is used as the paper P used for printing. Determine whether it is specified.

  When the special paper is designated (step S201: YES), the control unit 110 advances the process to step S202. On the other hand, when the special paper is not designated (step S201: NO), the control unit 110 advances the process to step S207.

(Step S202)
The control unit 110 functions as the setting unit 310, and executes the same processing as step S104 to determine whether the non-linear end of the sheet P set in the sheet storage unit 130 is on the leading end side in the sheet feeding direction. To determine.

  Then, if the non-linear end of the sheet P set in the sheet storage unit 130 is the leading end side in the sheet feeding direction (step S202: YES), the control unit 110 advances the process to step S203. On the other hand, when the non-linear end of the sheet P set in the sheet storage section 130 is not the leading end side in the sheet feeding direction (step S202: NO), the control section 110 advances the process to step S205.

(Step S203)
When the process proceeds to step S203, control unit 110 functions as setting unit 310, and uses the pair of rear end registration rollers 141, 142, 143, and 144 for bending correction when forming an image on the first surface of sheet P. Decide to do.

(Step S204)
Subsequently, the control unit 110 functions as the setting unit 310 and determines to use the leading edge registration roller pair 145 for bending correction when an image is formed on the second surface of the paper P.

  After that, the control unit 110 ends the setting processing for both sides.

(Step S205)
On the other hand, when the process proceeds from step S202 to step S205, the control unit 110 functions as the setting unit 310, and uses the pair of leading end resist rollers 145 for bending correction when forming an image on the first surface of the sheet P. Decide on that.

(Step S206)
Subsequently, the control unit 110 functions as the setting unit 310, and determines to use the pair of rear end registration rollers 141, 142, 143, and 144 for bending correction when forming an image on the second surface of the sheet P. .

  After that, the control unit 110 ends the setting processing for both sides.

(Step S207)
When the process proceeds from step S201 to step S207, the control unit 110 functions as the setting unit 310, and determines to use the leading end registration roller pair 145 on both the first surface and the second surface of the sheet P.

  After that, the control unit 110 ends the setting processing for both sides.

  The above-described setting processing for both sides is performed in the image forming apparatus 100. Thereby, in the case of double-sided printing, it can be determined which of the leading end registration roller pair 145 and the trailing end registration roller pair 141, 142, 143, 144 is used for correcting the bending of the first side and the second side of the sheet P. .

(3) Print control processing (single-sided printing and face-up printing)
FIG. 8 is a flowchart of print control processing when single-sided printing and face-up printing are instructed in the setting processing described above. Note that the print control process is executed in the image forming apparatus 100.

  When the control unit 110 of the image forming apparatus 100 receives a print (copy) start instruction from the user via the touch panel unit 120, the control unit 110 starts a print control process (single-sided printing and face-up printing). However, the present invention is not limited to this, and the control unit 110 may subsequently start the print control process after the end of the setting process described above.

(Step S301)
When the print control process is started, the control unit 110 drives a paper feed roller and the like, and starts conveying (feeding) the paper P stored in the paper storage unit 130. At this time, the sheet P is conveyed to the position of the bending correction unit 140.

(Step S302)
The control unit 110 functions as the correction control unit 320 and performs the rear end registration operation.

  FIG. 9 is a diagram for explaining the trailing edge registration operation (first half) when the length in the paper transport direction is short. FIG. 10 is a diagram for explaining the trailing edge registration operation (second half) when the length in the sheet conveyance direction is short. The trailing edge registration operation when the length in the paper transport direction is short proceeds in the order of FIGS. 9A, 9B, 10C, 10A, 10B, and 10C.

  First, as shown in the upper and lower views of FIGS. 9A and 9B, the control unit 110 rotates the tip resist roller pair 145 and the transport roller pairs 141, 142, 143, and 144 in the forward direction, The paper P (broken line in the figure below) is conveyed in the direction of the image forming unit 150.

  When the leading edge of the sheet P passes through the leading edge registration roller pair 145, the control unit 110 reversely rotates the leading edge registration roller pair 145 and the transport roller pairs 141, 142, 143, and 144 to reverse the transport direction of the sheet P. Let

  Further, prior to the trailing edge registration operation, the control unit 110 abuts the trailing edge of the paper P from the plurality of transport roller pairs 141, 142, 143, and 144 arranged on the upstream side of the leading edge registration roller pair 145. Select the rear end registration roller pair for this purpose.

  Specifically, the control unit 110 selects one trailing end registration roller pair in accordance with the length of the sheet P in the conveyance direction. In the example of the sheet P shown in FIGS. 9 and 10, when the leading end of the sheet P passes through the pair of leading end registration rollers 145, the control unit 110 controls the nearest third conveyance located on the upstream side of the trailing end of the sheet P. The roller pair 143 is selected as the trailing end resist roller pair.

  Then, in the trailing edge registration operation, the control unit 110 transports the paper P until the trailing edge thereof abuts against the third conveyance roller pair 143 selected as the trailing edge registration roller pair.

  When the trailing edge of the sheet P abuts against the trailing edge registration roller pair 143, the control unit 110 separates the leading edge registration roller pair 145, as shown in the upper and lower views of FIG. 9C.

  Thereafter, as shown in the upper and lower views of FIG. 9C, the control unit 110 causes the fourth conveyance roller pair 144 to nip the paper P while the sheet P is in contact with the trailing end registration roller pair 143. In the state, the sheet is conveyed by a predetermined amount without changing the conveyance direction. As a result, a loop (deflection) of the sheet P is formed between the trailing end registration roller pair 143 and the fourth conveyance roller pair 144.

  After forming a loop of a certain amount or more, as shown in the upper and lower views of FIG. The conveyance of the paper P in the direction is started, and the fourth conveyance roller pair 144 is separated. At this time, the bending of the sheet P is corrected.

  Thereafter, the control unit 110 further reverses the transport direction of the paper P and transports the paper P in the direction of the image forming unit 150 as shown in the upper and lower diagrams of FIGS. At this time, the control unit 110 returns the fourth transport roller pair 144 and the leading edge registration roller pair 145 in the separated state to the pressure-bonding state at the timing when the leading edge of the paper P passes. This is to prevent bending of the sheet P when the transport roller pair nips the non-linear end.

  The trailing edge registration operation (first half) when the length of the paper P in the transport direction is long will also be described.

  FIG. 11 is a diagram for explaining the trailing edge registration operation (first half) when the length in the paper transport direction is long. FIG. 12 is a diagram for explaining the trailing edge registration operation (second half) in the case where the length in the sheet conveyance direction is long. When the length in the paper transport direction is long, the trailing edge registration operation proceeds in the order of FIGS. 11 (A), (B), (C), and FIGS. 12 (A), (B), (C).

  First, as shown in the upper and lower views of FIGS. 11A and 11B, the control unit 110 rotates the tip resist roller pair 145 and the transport roller pairs 141, 142, 143, and 144 in the forward direction, The paper P (broken line in the figure below) is conveyed in the direction of the image forming unit 150.

  When the leading edge of the sheet P passes through the leading edge registration roller pair 145, the control unit 110 reversely rotates the leading edge registration roller pair 145 and the transport roller pairs 141, 142, 143, and 144 to reverse the transport direction of the sheet P. Let

  Further, the control unit 110 controls the plurality of conveyance roller pairs 141, 142, 143 disposed upstream of the leading end registration roller pair 145 prior to the rear end registration operation, as in the case where the length in the conveyance direction of the sheet is short. The trailing edge registration roller pair is selected from 144. In the example of the sheet P shown in FIGS. 11 and 12, when the leading end of the sheet P passes through the pair of leading end registration rollers 145, the control unit 110 sets the first conveyance closest to the upstream side of the trailing end of the sheet P. The roller pair 141 is selected as the trailing end resist roller pair.

  In the trailing edge registration operation, the control unit 110 transports the paper P until the trailing edge of the sheet P hits the first conveyance roller pair 141 selected as the trailing edge registration roller pair.

  When the trailing edge of the sheet P abuts against the trailing edge registration roller pair 141, the control unit 110 separates the leading edge registration roller pair 145, as shown in the upper and lower views of FIG. At the same time, the control unit 110 includes a pair of conveyance rollers other than the conveyance roller pair 142 used for abutting control to the rear end registration roller pair 141 among the conveyance roller pairs arranged on the downstream side of the rear end registration roller pair 141. 143, 144 are separated. This is to minimize the transport roller pair used for the transport roller pair used for abutment control, and to prevent the sheet P from being bent.

  Thereafter, as shown in the upper and lower views of FIG. 11C, the control unit 110 causes the second conveyance roller pair 142 to nip the paper P while the sheet P is in contact with the trailing end registration roller pair 141. In the state, the sheet is conveyed by a predetermined amount without changing the conveyance direction. As a result, a loop (deflection) of the sheet P is formed between the trailing end registration roller pair 141 and the second conveyance roller pair 142.

  After forming a loop of a certain amount or more, as shown in the upper and lower views of FIG. 12A, the control unit 110 causes the sheet P to be nipped by the rear end registration roller pair 141, and opposite to the image forming unit 150. The conveyance of the paper P in the direction is started, and the second conveyance roller pair 142 is separated. At this time, the bending of the paper P is corrected.

  Thereafter, the control unit 110 further reverses the transport direction of the paper P and transports the paper P in the direction of the image forming unit 150 as shown in the upper and lower diagrams of FIGS. At this time, the control unit 110 returns the pressure contact state in order from the transport roller pair through which the leading end of the sheet P has passed among the transport roller pairs 142, 143, 144 and the leading end registration roller pair 145 in a separated state. However, among the transport roller pairs 142, 143, and 144 in the separated state, the transport roller pair unnecessary for transporting the sheet P (for example, the second and third transport roller pairs 142 and 143) is kept separated. . This minimizes the conveyance roller pair used to convey the sheet P after the rear end registration operation to the image forming unit 150, and prevents the sheet P from being bent based on variations in diameter and alignment between the conveyance roller pairs. In order to

  Thereafter, the control unit 110 forwardly rotates at least the front registration roller pair 145 to send the paper P to the transfer position of the image forming unit 150, and then advances the processing to step S303.

(Step S303)
Returning to FIG. 8, the control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image onto the paper P. Thereafter, the control unit 110 rotates a predetermined transport roller (not shown) in the forward direction to transport the paper P to the fixing unit 160. The fixing unit 160 fixes the toner image transferred onto the sheet P by heating the sheet P.

(Step S304)
Thereafter, the control unit 110 functions as the paper discharge control unit 330 and drives a paper discharge roller or the like to start conveyance (paper discharge) of the paper P. At this time, the paper P is discharged onto the paper discharge unit 170 in a face-up state without the front and back being reversed.

(Step S305)
After discharging the sheet P, the control unit 110 determines whether it is time to end the print control process. For example, when copying of all pages included in the document is completed, or when printing of all pages included in the print job is completed, control unit 110 determines that it is the timing for ending the print control process (step (S305: YES), the print control process is terminated. On the other hand, if there are still pages to be copied or printed, the control unit 110 determines that it is not time to end the print control process (step S305: NO), and returns the process to step S301.

  As described above, when the single-sided printing and the face-up printing are instructed, the image forming apparatus 100 selects the trailing end registration roller pair 141, 142, 143, and 144 to perform the bending correction, and one end of the linear shape The paper P is discharged in a state in which is directed toward the rear end side in the transport direction. Therefore, the straight end portion can be abutted against the rear end registration roller pair 141, 142, 143, 144 to correct the bending, and the linear end portion can be discharged so as to contact the reference surface of the discharge tray. . As a result, it is possible to ensure consistency at the time of paper discharge without lowering the accuracy of bending correction.

(4) Print control processing (single-sided printing and face-down printing)
FIG. 13 is a flowchart of print control processing when single-sided printing and face-down printing are instructed in the setting processing described above. Note that the print control process is executed in the image forming apparatus 100.

  When receiving a print (copy) start instruction from the user via the touch panel unit 120 from the user, the control unit 110 of the image forming apparatus 100 starts a print control process (single-sided printing and face-down printing). However, the present invention is not limited to this, and the control unit 110 may subsequently start the print control process after the end of the setting process described above.

(Step S401)
When the print control process is started, the control unit 110 drives a paper feed roller and the like, and starts conveying (feeding) the paper P stored in the paper storage unit 130. At this time, the sheet P is conveyed to the position of the bending correction unit 140.

(Step S402)
The control unit 110 functions as the correction control unit 320, and performs the tip registration operation.

  FIG. 14 is a diagram for explaining the tip registration operation (first half). FIG. 15 is a diagram for explaining the tip registration operation (second half). The tip resisting operation proceeds in the order of FIGS. 14 (A), (B), (C), and FIGS. 15 (A), (B).

  First, as shown in the upper and lower views of FIG. 14A, the control unit 110 rotates the conveyance roller pairs 141, 142, 143, and 144 in the forward direction to form the sheet P (broken line in the lower view). The sheet is conveyed until the leading edge hits the pair of leading edge registration rollers 145.

  When the leading edge of the sheet P hits the leading edge registration roller pair 145, the control unit 110, as shown in the upper and lower views of FIG. The conveyance roller pairs 141, 142, and 143 other than the pair 144 are separated from each other.

  Thereafter, as shown in the upper and lower views of FIG. 14C, the control unit 110 rotates only the fourth transport roller pair 144 while keeping the sheet P in contact with the leading end resist roller pair 145. As a result, a loop (deflection) of the sheet P is formed between the leading registration roller pair 145 and the fourth conveyance roller pair 144.

  After forming a loop of a fixed amount or more, as shown in the upper and lower views of FIG. While the conveyance of P is started, the fourth conveyance roller pair 144 is separated. At this time, the bending of the sheet P is corrected.

  Thereafter, as shown in the upper and lower views of FIG. 15B, the control unit 110 rotates at least the front end resist roller pair 145 forward to deliver the sheet P to the transfer position of the image forming unit 150, and then performs processing. Proceed to step S403.

(Step S403)
Returning to FIG. 13, the control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image onto the paper P. Thereafter, the control unit 110 rotates a predetermined transport roller (not shown) in the forward direction to transport the paper P to the fixing unit 160. The fixing unit 160 fixes the toner image transferred onto the sheet P by heating the sheet P.

(Step S404)
Thereafter, the control unit 110 functions as the discharge control unit 330, and reverses the front and back of the sheet P on which the image is formed. Specifically, the control unit 110 transports the paper P from the point D to the point F shown in FIG. 1, then reverses the transport direction and transports the paper P from the point F to the point E.

(Step S405)
The control unit 110 functions as a paper discharge control unit 330 and drives a paper discharge roller or the like to discharge the paper P. At this time, the sheet P is discharged onto the sheet discharge unit 170 in a face-down state.

(Step S406)
After discharging the sheet P, the control unit 110 determines whether it is time to end the print control process. For example, when copying of all pages included in the document is completed, or when printing of all pages included in the print job is completed, control unit 110 determines that it is the timing for ending the print control process (step S406: YES), the print control process is terminated. On the other hand, when there is still a page to be copied or printed, the control unit 110 determines that it is not the timing to end the print control process (step S406: NO), and returns the process to step S401.

  As described above, when the single-sided printing and face-down printing are instructed, the image forming apparatus 100 selects the leading-end registration roller pair 145, performs bending correction, and sets the linear end to the rear end side in the transport direction. The sheet P is discharged in the state of being directed. For this reason, the straight end portion can be abutted against the tip registration roller pair 145 to correct the bend, and the straight end portion can be discharged so as to contact the reference surface of the discharge tray. As a result, it is possible to ensure consistency at the time of paper discharge without lowering the accuracy of bending correction.

(5) Print control processing (double-sided printing)
FIG. 16 is a flowchart of print control processing when duplex printing is instructed in the setting processing described above. Note that the print control process is executed in the image forming apparatus 100.

  When the control unit 110 of the image forming apparatus 100 receives a print (copy) start instruction from the user via the touch panel unit 120, the control unit 110 starts a print control process (double-sided printing). However, the present invention is not limited to this, and the control unit 110 may subsequently start the print control process after the end of the setting process described above.

(Step S501)
When the print control process is started, the control unit 110 drives a paper feed roller and the like, and starts conveying (feeding) the paper P stored in the paper storage unit 130. At this time, the sheet P is conveyed to the position of the bending correction unit 140.

(Step S502)
If it is determined that the non-linear end of the sheet P set in the sheet storage unit 130 is on the leading end side in the sheet feeding direction (step S502: YES), the control unit 110 determines in step S202 described above Advances to step S503. On the other hand, when it is determined that the non-linear end of the sheet P set in the sheet storage portion 130 is on the rear end side in the sheet feeding direction in step S202 described above (step S502: NO) ), The process proceeds to step S509.

(Step S503)
When the process proceeds to step S503, the control unit 110 functions as the correction control unit 320, and performs a trailing edge registration operation before an image is formed on the first surface of the paper P. The rear end registration operation in step S503 is similar to the operation in step S302 described above, and thus the description thereof is omitted.

(Step S504)
The control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image to the first surface of the paper P. Thereafter, the control unit 110 causes the sheet P to be conveyed to the fixing unit 160 by rotating a predetermined conveyance roller (not shown) forward. The fixing unit 160 fixes the toner image transferred onto the first surface of the sheet P on the sheet P by heating.

(Step S505)
Thereafter, the control unit 110 conveys the paper P to the paper reversing unit 180, reverses the front and back of the paper P on which the image is formed on the first side, and enables the image forming unit 150 to form an image on the second side. Do. For example, the sheet P on which the image of the first side is formed is conveyed from the point F to the point G shown in FIG. 1, and then the conveyance direction is reversed, and the sheet P is conveyed from the point G to the point B via the point H. Be done.

(Step S506)
When the process proceeds to step S506, the control unit 110 functions as the correction control unit 320, and performs the leading edge registration operation before the image is formed on the second surface of the paper P. The tip registration operation in step S506 is the same as that in step S402 described above, and thus the description thereof is omitted.

(Step S507)
The control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image onto the second surface of the paper P. Thereafter, the control unit 110 rotates a predetermined transport roller (not shown) in the forward direction to transport the paper P to the fixing unit 160. The fixing unit 160 fixes the toner image transferred onto the second surface of the sheet P on the sheet P by heating.

(Step S508)
Thereafter, the control unit 110 functions as the paper discharge control unit 330 and reverses the front and back of the paper P on which images are formed on both the first side and the second side. Specifically, the control unit 110 transports the paper P from the point D to the point F shown in FIG. 1, then reverses the transport direction and transports the paper P from the point F to the point E. And the control part 110 advances a process to step S514.

(Step S509)
On the other hand, when the process proceeds from step S502 to step S509, the control unit 110 functions as the correction control unit 320, and performs the leading edge resist operation before an image is formed on the first surface of the sheet P. The tip registration operation in step S509 is the same as that in step S402 described above, and thus the description thereof is omitted.

(Step S510)
The control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image to the first surface of the paper P. Thereafter, the control unit 110 rotates a predetermined transport roller (not shown) in the forward direction to transport the paper P to the fixing unit 160. The fixing unit 160 fixes the toner image transferred onto the first surface of the sheet P on the sheet P by heating.

(Step S511)
Thereafter, the control unit 110 conveys the paper P to the paper reversing unit 180, reverses the front and back of the paper P on which the image is formed on the first side, and enables the image forming unit 150 to form an image on the second side. Do. For example, the sheet P on which the image of the first side is formed is conveyed from the point F to the point G shown in FIG. 1, and then the conveyance direction is reversed, and the sheet P is conveyed from the point G to the point B via the point H. Be done.

(Step S512)
When the process proceeds to step S512, the control unit 110 functions as the correction control unit 320, and performs a trailing edge registration operation before an image is formed on the second surface of the paper P. The trailing edge registration operation in step S512 is the same as that in step S302 described above, and thus the description thereof is omitted.

(Step S513)
The control unit 110 controls the image forming unit 150 to form a toner image by an image forming process such as an electrophotographic method, and transfers the toner image onto the second surface of the paper P. Thereafter, the control unit 110 causes the sheet P to be conveyed to the fixing unit 160 by rotating a predetermined conveyance roller (not shown) forward. The fixing unit 160 fixes the toner image transferred onto the second surface of the sheet P on the sheet P by heating. Then, the control unit 110 advances the process to step S514 without reversing the front and back of the sheet P.

(Step S514)
When the process proceeds to step S514, the control unit 110 functions as the paper discharge control unit 330 and drives the paper discharge roller and the like to discharge the paper P. At this time, the paper P is discharged onto the paper discharge unit 170.

(Step S515)
After discharging the sheet P, the control unit 110 determines whether it is time to end the print control process. For example, when copying of all pages included in the document is completed, or when printing of all pages included in the print job is completed, control unit 110 determines that it is the timing for ending the print control process (step S515: YES), the print control process is terminated. On the other hand, when there is still a page to be copied or printed, the control unit 110 determines that it is not the timing to end the print control process (step S515: NO), and returns the process to step S501.

  As described above, when an image is formed on the first side and the second side of the sheet P, the image forming apparatus 100 selects different resist roller pairs to correct bending when forming an instruction on double-sided printing. Do. Therefore, no matter which direction the paper P is set in the paper storage unit 130, the linear end portion is abutted against any one of the front end registration roller pair 145 and the rear end registration roller pair 141, 142, 143, 144. You can correct the curve. Further, at the time of sheet discharge, since the sheet P is discharged with the linear end directed to the rear end side in the transport direction, the linear end is in contact with the reference surface of the sheet discharge tray. It can be discharged. As a result, it is possible to ensure consistency at the time of paper discharge without lowering the accuracy of bending correction.

  In addition, regardless of which one of single-sided printing and face-up printing (FIG. 8), single-sided printing and face-down printing (FIG. 13), and double-sided printing (FIG. 16) is specified, the accuracy of bending correction is reduced. No, it is possible to ensure consistency at the time of paper discharge.

  Further, in the above embodiment, the rear end registration roller pair 141, 142, 143, 144 is a position where the conveyance path from the sheet storage unit 130 to the image forming unit 150 and the conveyance path of the sheet reversing unit 180 merge It is disposed in the linear conveyance path that is closer to the image forming unit 150 than the point B) and upstream from the tip registration roller pair 145. Therefore, the distance for conveying the sheet P to the image forming position after the correction of the bend by the rear end registration operation is short, and the correction of the bend is not performed in the curved path. It can prevent that it occurs.

  Further, in the above embodiment, the control unit 110 selects one trailing end registration roller pair in accordance with the length of the sheet P in the conveyance direction. Thereby, the conveyance distance to the image forming unit 150 of the sheet P after the trailing edge registration operation and the conveyance roller pair to be used can be minimized.

  Note that each processing unit in each flowchart described above is divided according to the main processing content in order to facilitate understanding of the image forming apparatus 100. The invention of the present application is not limited by the method of classification of the processing steps and the names thereof. The processing performed in the image forming apparatus 100 can be divided into more processing steps. One processing step may execute more processes.

<Modification>
Further, the above embodiments are intended to illustrate the subject matter of the present invention, and are not intended to limit the present invention. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

  For example, as compared with the case where the leading end of the paper P is abutted against the front registration roller pair 145 to correct the bending, the rear end of the paper P is abutted against the rear end registration roller pair 141, 142, 143, 144 to correct the bending. When performing the above, the conveyance speed of the paper P may be increased. Thereby, it is possible to prevent a decrease in productivity due to the reverse conveyance of the paper P.

  In the above-described embodiment, rubber having a large area in contact with the paper P is used for the front registration roller pair 145 and the plurality of transport roller pairs 141, 142, 143, and 144 that can be selected as the rear registration roller pair. It is done. Therefore, the front registration roller pair 145 and the rear registration rollers 141, 142, 143, and 144 have a higher conveyance force than the other conveyance roller pairs. Thus, it is possible to prevent the sheet P from being bent due to the influence of the leading end registration roller pair 145 and the conveyance rollers other than the trailing end registration roller pair 141, 142, 143, 144 during the registration operation. You can correct the bend.

  Further, in the above-described embodiment, there is a retraction path for retreating the front end side of the paper P before the rear end of the paper P is abutted against the rear end registration roller pair 141, 142, 143, 144 and the bending correction is performed. (Conveyance path between C and C ′ shown in FIG. 1). As a result, even if the length of the sheet P in the transport direction is long, the transport roller pair (for example, the fourth transport roller pair 144, the fourth transport roller pair 144 The three transport roller pair 43) can be used as the rear end registration roller pair. As a result, it is possible to minimize the transport distance of the sheet P after the rear end registration operation to the image forming unit 150 and the transport roller pair to be used.

  In addition, instead of providing the above-described retraction path, the control unit 110 causes the rear end of the sheet P to abut against the rear end registration roller pairs 141, 142, 143, and 144 before performing the bending correction, and the transfer roller pair 155 and The fixing roller pair (fixing unit 160) may be separated. As a result, the leading end side of the sheet P can be retracted in the space generated between the transfer roller pair 155 and the fixing roller pair without providing a retraction path, as in the case of providing the retraction path. An effect is obtained. However, the leading end side of the sheet P may be retracted in the space formed between the transfer roller pair 155 and between the fixing roller pair after providing the above-described retract path.

  Further, the control unit 110 abuts the leading edge of the sheet P against the leading edge registration roller pair 145 to correct the bending, and the trailing edge of the sheet P abuts against the trailing edge registration roller pair 141, 142, 143, 144. The loop amount and the abutment time of the sheet P generated by the abutment may be different depending on the case where the bending correction is performed. For example, at the time of envelope printing, the bending amount can be accurately corrected by varying the loop amount and the abutting time of the paper P caused by abutting according to the difference in rigidity between the front surface and the back surface.

  In steps S104, S106, and S202 of the above-described embodiment, the control unit 110 receives information on the orientation of the paper P set in the paper storage unit 130 from the user via the touch panel unit 120, and the orientation of the paper P Is reliably determined. However, the present invention is not limited to this, and may include a detection unit that automatically detects the orientation of the sheet P set in the sheet storage unit 130. At this time, the setting unit 310 refers to the detection value obtained by the detection unit, and determines whether the non-linear end of the paper P is the front end side in the transport direction or the rear end side in the transport direction. It may be determined which of the leading registration roller pair and the trailing registration roller pair should be used for the bending correction. As a result, in steps S104, S106, and S202, the user can omit the operation of confirming the orientation of the sheet P set in the sheet storage unit 130.

  FIG. 17 is a view showing the sensors 131a and 131b for automatically detecting the direction of the sheet P. As illustrated in FIG. 17, the detection unit includes a plurality of sensors 131 a and 131 b provided in the sheet storage unit 130 and arranged in the width direction of the sheet P. Then, the setting unit 310 does not form a straight line of the paper P set in the paper storage unit 130 based on a difference between detection values obtained from the sensors 131a and 131b (for example, a difference in arrival time and passage time). It is determined whether one end is the front end side in the transport direction or the rear end side in the transport direction. As described above, the orientation of the sheet P can be automatically detected by the simple configuration in which only the sensors 131a and 131b are provided in the sheet storage unit 130. However, in order to automatically detect the direction of the sheet P using the sensors 131a and 131b, it is necessary to transport the sheet P. Therefore, after the completion of steps S103 and S201 described in the above embodiment, the print control processing shown in FIGS. 8, 13, and 16 must be started in parallel with this.

  Further, in the above embodiment, the four conveying roller pairs 141, 142, 143, 144 are selectable as the trailing edge resist roller pair. However, in the present invention, as long as a plurality of conveyance roller pairs are arranged, it is not necessary to limit the number of conveyance roller pairs that can be selected as the rear end registration roller pair to four.

  Although not illustrated, various post-processing devices may be connected to the image forming apparatus 100.

  The configuration of the above-described image forming apparatus 100 is the main configuration described in describing the features of the above-described embodiments, and is not limited to the above-described configuration. Further, the configuration provided in the general image forming apparatus 100 is not excluded.

  Also, each functional configuration of the image forming apparatus 100 shown in FIG. 4 is classified according to the main processing content in order to facilitate understanding of each functional configuration. The invention is not limited by the classification method and names of components. Each functional configuration can also be classified into more components according to the processing content. Also, one component can be classified to perform more processing.

  The processing of each functional configuration shown in FIG. 4 can also be realized by a dedicated hardware circuit. In this case, it may be implemented with one hardware or with multiple hardware.

  The program for operating the image forming apparatus 100 may be provided by a computer-readable recording medium such as a USB (Universal Serial Bus) memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), or the Internet. , Etc. may be provided online via a network. In this case, the program recorded on the computer readable recording medium is usually transferred to and stored in a memory, storage or the like. Also, this program may be provided, for example, as a single application software, or may be incorporated into the software of each apparatus as one function of the image forming apparatus 100.

100 image forming devices,
110 control unit,
120 touch panel section,
130 paper storage unit,
140 curve correction unit,
141 First conveying roller pair,
142 second transport roller pair,
143 The third transport roller pair,
144 Fourth transport roller pair,
145 Pair of leading edge registration rollers,
150 image forming units,
155 Transfer roller pair,
160 fixing unit,
170 paper output unit,
180 sheet reversing unit,
310 setting unit,
320 correction control unit,
330 paper discharge control unit,
340 Notification Department.

Claims (16)

A paper storage section for storing paper;
An image forming unit that forms an image on the sheet fed from the sheet storage unit;
A paper reversing unit that reverses the front and back of the paper on which the image is formed on the first surface by the image forming unit, and enables the image forming unit to form an image on the second surface;
A tip resist roller pair disposed at a position for delivering the sheet to the image forming unit;
A straight line that is closer to the image forming unit than the position where the conveyance route from the sheet storage unit to the image forming unit and the conveyance route of the sheet reversing unit merge, and on the upstream side of the pair of front end resist rollers A trailing edge registration roller pair disposed in a sheet-like conveyance path;
When one end on the leading end side of the sheet in the conveyance direction is linear, the leading end of the sheet is abutted against the pair of leading end resist rollers to perform bending correction, and one end on the leading end side in the conveyance direction of the sheet is not linear In this case, a correction control unit that reverses the conveyance direction of the paper and corrects the bending by abutting the trailing edge of the paper against the trailing edge registration roller pair;
A discharge control unit that discharges the sheet in a state where one end of the linear shape is directed to the rear end side in the transport direction;
An image forming apparatus comprising: The correction control unit
In the case where the trailing edge of the sheet is abutted against the pair of trailing edge registration rollers to correct the bending, the trailing edge of the sheet is abutted against the pair of trailing edge registration rollers, and then the pair of trailing edge registration rollers is used. 2. The image forming apparatus according to claim 1, wherein the sheet is nipped and conveyed by a predetermined amount without changing the conveying direction, and then the sheet is conveyed in the direction of the image forming unit by reversing the conveying direction of the sheet. The correction control unit
Compared to the case where the leading edge of the sheet is abutted against the pair of leading edge registration rollers to correct the bending, the sheet is corrected when the sheet is corrected by bending the trailing edge of the sheet against the pair of trailing edge registration rollers. The image forming apparatus according to claim 1, wherein the transport speed is increased.   The trailing edge registration roller pair is selected from a plurality of conveyance roller pairs arranged on the upstream side of the leading edge registration roller pair according to the length of the paper in the conveyance direction. The image forming apparatus according to claim 1. The correction control unit
While the rear end of the sheet is abutted against the rear end registration roller pair, of the transport roller pair arranged on the downstream side of the rear end registration roller pair, for the abutting control to the rear end registration roller pair The image forming apparatus according to claim 4, wherein a transport roller pair other than the transport roller pair used is separated. The correction control unit
When the paper is abutted against the trailing edge registration roller pair and then transported in the direction of the image forming unit, among the transport roller pairs in a separated state, from the transport roller pair through which the leading edge of the paper has passed. The image forming apparatus according to claim 5, wherein the image forming apparatus is returned to the crimped state in order. The correction control unit
Regarding the transport roller pair which is not necessary for transporting the sheet among the transport roller pair in a separated state when transporting the sheet in the direction of the image forming unit after the sheet is abutted against the rear end registration roller pair The image forming apparatus according to claim 6, wherein the image forming apparatus is separated.   The transporting force of the plurality of transport roller pairs that can be selected as the front-end registration roller pair and the rear-end registration roller pair is higher than that of other transport roller pairs, according to any one of claims 4 to 7. Image forming apparatus.   The retreat path for retracting the front end side of the paper is provided before the rear end of the paper is brought into contact with the rear end registration roller pair to perform bending correction. Image forming apparatus. The image forming unit includes a transfer roller pair and a fixing roller pair,
The correction control unit
Before performing the correction of bending by abutting the trailing edge of the sheet against the trailing edge registration roller pair, the transfer roller pair and the fixing roller pair are separated from each other, and the leading end side of the sheet is placed in the space generated by the separation. The image forming apparatus according to any one of claims 1 to 9, wherein the image forming apparatus is retracted. The correction control unit
The case where the leading edge of the paper is abutted against the pair of front end registration rollers and the bending correction is performed, and the case where the rear end of the sheet is abutted against the pair of rear end registration rollers and the bending correction is performed, The image forming apparatus according to any one of claims 1 to 10, wherein the loop amount and abutment time of the sheet are made different.   The input of information related to the orientation of the paper set in the paper storage unit is received, and the paper is bent according to whether the non-linear end of the paper is the leading end in the transport direction or the rear end in the transport direction. The image forming apparatus according to any one of claims 1 to 11, further comprising a setting unit that determines which of the leading end registration roller pair and the rear end registration roller pair is to be used for correction. A detection unit that detects an orientation of the sheet set in the sheet storage unit;
With reference to the detection value obtained by the detection unit, the leading edge resist roller is used to correct the bending of the sheet according to whether the one end of the sheet is not the straight end of the sheet is the leading end side in the conveying direction The image forming apparatus according to claim 1, further comprising: a setting unit that determines which of the pair and the rear end registration roller pair to use. The detection unit includes a plurality of sensors arranged in the width direction of the sheet.
The setting unit sets the non-linear end of the sheet set in the sheet storage unit to the front end side in the transport direction or the rear end side in the transport direction based on a difference between detection values obtained from the respective sensors. The image forming apparatus according to claim 13, wherein it is determined whether or not there is.   When single-sided printing and face-up printing are specified and the non-linear end of the paper set in the paper storage unit is the rear end side in the transport direction, or single-sided printing and face-down printing is specified and the paper storage 15. The notification unit according to claim 1, further comprising: a notification unit that notifies that the orientation of the sheet should be changed when the non-linear end of the sheet set in the unit is the leading end side in the transport direction. The image forming apparatus according to one item. A paper storage section for storing paper;
An image forming unit that forms an image on the sheet fed from the sheet storage unit;
A paper reversing unit that reverses the front and back of the paper on which the image is formed on the first surface by the image forming unit, and enables the image forming unit to form an image on the second surface;
A tip resist roller pair disposed at a position for delivering the sheet to the image forming unit;
A straight line that is closer to the image forming unit than the position where the conveyance route from the sheet storage unit to the image forming unit and the conveyance route of the sheet reversing unit merge, and on the upstream side of the pair of front end resist rollers And a rear end registration roller pair disposed in the conveyance path
(A) when one end on the leading end side in the transport direction of the sheet is linear, a procedure for correcting the bending by abutting the leading end of the sheet against the pair of leading end registration rollers;
(B) In the case where one end on the front end side of the sheet in the conveyance direction is not linear, the conveyance direction of the sheet is reversed, and the rear end of the sheet is abutted against the pair of rear end registration rollers When,
(C) discharging the paper, which has been subjected to the bending correction according to at least one of the procedure (a) and the procedure (b), with a linear end facing the rear end in the transport direction;
Control program for image forming apparatus for executing