JP2008265987A - Curl correction device and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curl correction device capable of conveying paper capable of being post-treated with good accuracy to a post-treatment device taking into consideration characteristic of the post-treatment device in the curl correction device capable of performing curl correction not depending on a curl direction of the paper. <P>SOLUTION: The curling correction device having a conveying passage is provided, in which a curling correction direction is different relative to an adjacent curling correction part, the curling correction part having the highest curling correction force is provided in an upstream side in a conveying direction, and the curling correction part is arranged such that the curling correction force gradually becomes small from the curling correction part toward the downstream side in the conveying direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a curl correction apparatus that corrects paper curl and an image forming system including the curl correction apparatus.

  In recent years, electrophotographic image forming apparatuses have been used in the field of light printing such as POD (Print On Demand), and in response to demands for image quality and high speed, various post-processing can be performed with high accuracy. It is required that it can be processed.

  The sheet on which the image is formed by the electrophotographic image forming apparatus is fixed by heating the toner image on the surface thereof with a fixing device. The paper may be curled (also referred to as a curl) due to the difference between the heating at the time of fixing and the expansion and contraction of the front and back of the paper that occurs at the time of subsequent heat dissipation.

  In such a curled paper, there is a curling problem in the conveyance failure problem due to the curl of the paper being caught in the conveyance path at the time of conveyance, and in the process of aligning the bundle of the paper and performing the post-processing. The sheet bundle becomes uneven, and there arises a problem that the post-processing cannot be performed with high accuracy.

  Therefore, there is a curl correction device as a device for correcting the curl of the paper. The curl correction device generally reduces the original curl amount by attaching curl in the direction opposite to the direction in which the paper curls. However, the curl direction and curl amount of paper may differ greatly depending on paper characteristics such as paper basis weight, eye direction, and unsealed surface, the amount of toner transferred to the paper, and image forming conditions of the fixing device. is there. In such a case, in the method of forcing the curl in one direction with a single curl correction device, if the curl direction of the paper is opposite to the target direction, the curl correction by the curl correction device Since the direction is the same as the original curl direction, there is an adverse effect of increasing the curl amount.

Patent Document 1 discloses a curl removing device that predicts a curl state from a detection result of a moisture content detection unit of a sheet and adjusts a curl correction amount of the curl correction unit from the predicted curl state. In Patent Document 2, a curl correction device that varies a curl correction force by winding a belt around a conveyance roller and changing the winding angle, and a curl correction device that changes a curl correction force according to the type or image density of a sheet. Is disclosed.
Japanese Patent Laid-Open No. 4-251067 JP-A-5-341600

  However, each of the curl correction apparatuses disclosed in Patent Document 1 or Patent Document 2 performs curl correction by predicting the curl amount, and the prediction accuracy is not sufficient. Will not work as expected. Further, since it has only one direction of curl correction function, it cannot cope with a sheet in which the curl in the other direction has occurred.

  Depending on the characteristics of the post-processing apparatus, there may be a curl direction that can be accurately post-processed and a curl direction that is not. When the curl direction after curl correction by the curl correction apparatus is a curl direction that cannot be accurately post-processed by the post-processing apparatus, the post-processing accuracy is deteriorated by correcting the curl.

  In view of the above problems, the present invention is a curl correction device capable of correcting curl without depending on the curl direction of the paper, and is capable of conveying a paper that can be accurately processed in consideration of the characteristics of the post-processing device to the post-processing device. The object is to obtain a possible curl correction device.

  The above object is achieved by the invention described below.

(1) A curl correction device for correcting curl generated on paper,
A transport path for transporting image-formed paper, comprising a transport path having a plurality of curl correction portions that curl and deform the paper to correct the curl;
The curl correction unit has a curl correction direction that is different from the adjacent curl correction unit and has the highest curl correction force on the upstream side in the conveyance direction, and extends from the curl correction unit toward the downstream side in the conveyance direction. The curl correction part is arranged so that the curl correction force gradually decreases, and
A post-processing device that performs post-processing on the image-formed paper bundle can be connected, and the curl correction direction at the curl correction unit on the most downstream side in the transport direction temporarily places the paper bundle of the post-processing device. A curl straightening device having a convex curl direction on a processing tray.

(2) having a first endless belt stretched on a plurality of rollers and a second endless belt stretched on the plurality of rollers;
The conveyance path is formed by the first endless belt and the second endless belt, and the correction section is formed by winding one endless belt around a roller facing the endless belt together with the other endless belt. (3) The curl correction apparatus according to (1).

  (3) The curl correction section has different curl correction forces by varying at least one of a diameter of the facing roller and a winding angle of the endless belt around the facing roller (1). Or the curl correction apparatus as described in (2).

(4) An image forming apparatus that forms an image on a sheet, and a curl correcting apparatus according to any one of (1) to (3) that performs curl correction on the sheet formed by the image forming apparatus.
A post-processing device that performs post-processing on paper that has been curled by the curl straightening device;
An image forming system comprising:

  According to the present invention, a curl correction device capable of correcting curl without depending on the curl direction of the paper, and a curl capable of conveying the paper that can be accurately processed in consideration of the characteristics of the post-processing device to the post-processing device. A correction device can be obtained.

  Although the present invention will be described based on an embodiment, the present invention is not limited to the embodiment.

  FIG. 1 is an overall view of an image forming system according to an embodiment of the present invention. The image forming system includes an image forming apparatus A, a curl correction apparatus B1, and a sheet post-processing apparatus B2.

[Image forming apparatus A]
The image forming apparatus A has an automatic document feeder 1 and an image reading unit 2 in the upper part, and the lower part is composed of a printer unit.

  In the printer section, 3 is a paper storage section for storing the paper S. An image is formed on the sheet S in the printer engine 5 that forms a toner image on the photoconductor 4 by an electrophotographic process in which the photoconductor 4 is charged, exposed, and developed. Is fixed. The fixing device 6 forms a nip for transporting the paper S by the heating roller 6b and the pressure roller 6c. The heating roller 6b includes a heat source 6a, and controls the heating roller 6b to a constant temperature by controlling the amount of heat generated by the heat source by a temperature sensor (not shown). While the sheet S is conveyed to the nip of the fixing device 6, the toner is melted by heating and pressing to fix the toner image on the sheet S.

  The sheet S is fed from the sheet storage unit 3 by the first sheet feeding unit 3a, and after being temporarily stopped by the second sheet feeding unit 3b, the sheet is fed and image formation is performed. The paper is discharged from the paper discharge port by the roller 8.

  As the transport path of the paper S, a paper feed path 7 from the paper storage unit 3 to the printer engine 5, a transport path 9 a from the printer engine 5 through the fixing device 6 and the paper discharge roller 8 to the paper discharge port, and an image formed. A double-sided conveyance path 9 b is provided for reversing the cover sheet, switching back, and conveying the sheet to the sheet feeding path 7 again.

  Reference numeral tp denotes an operation display unit, which includes a touch panel in which a touch screen is arranged on a display unit constituted by a liquid crystal panel. Various modes in the image forming apparatus A and output modes using the sheet post-processing apparatus B2 can be set by operations on the operation display unit tp.

  The control means C1 disposed in the image forming apparatus A is connected to the control means C2 of the curl correction apparatus B1 and the control means C3 of the sheet post-processing apparatus B2 via the communication means C4.

  The sheet S discharged from the image forming apparatus A is conveyed to the sheet post-processing apparatus B2 through the curl correction apparatus B1.

[Curl straightening device B1]
The curl correction apparatus B1 includes a main part 10, a gate G1, and a bypass conveyance path 130. When performing curl correction, the sheet is conveyed to the lower main part 10 by the gate G1 for switching the conveyance path, and the curl correction is performed. A sheet on which an image is not formed, a thick sheet, or other sheets that do not require curl correction are transported through the bypass transport path 130 and transported to the post-processing apparatus B2.

  The main part 10 has a first belt unit 11 and a second belt unit 12, and a conveying path 100 is formed by both belt units. By conveying the sheet to the conveying path 100, the sheet is decurled (curled). Details will be described later.

[Post-processing device B2]
The paper post-processing apparatus B2 performs various post-processing on the paper S discharged from the image forming apparatus A and transported by the curl correction apparatus B1, and includes a punching machine, a folding machine, a flat stitching machine, and a middle folding machine. A binding machine, a gluing bookbinding machine, a cutting machine, etc. are generically named.

  In the paper post-processing device B2, a staple device will be described as a representative example of the paper post-processing device B2 that performs post-processing on the paper that has been curled by the curl straightening device B1.

  The sheet post-processing device B2 includes, from the top in the figure, an insertion sheet feeding means 40, a shift means 20, a processing tray 30, and a stapling means 50 that contain insertion sheets (used for front and back covers). They are arranged in a column in a substantially vertical direction.

  In the processing tray 30, a plurality of sheets S on which images are formed by the image forming apparatus A are temporarily placed to create a sheet bundle. The paper placed on the processing tray 30 is subjected to vertical alignment in the transport direction and width alignment perpendicular to the vertical direction, and then staple processing is performed by the stapling unit 50 on the paper bundle.

  The shift unit 20 performs a shift process for changing the paper discharge position in the transport width direction for each predetermined number of sheets on the image-formed paper discharged from the image forming apparatus A.

  An inlet conveyance unit 70 is disposed on the upper right side of the sheet post-processing apparatus B2. In addition, on the left side of the sheet post-processing apparatus B2 in the figure, a movable sheet discharge tray 81 for discharging and stacking sheets on which images have been formed is disposed. The discharge tray 81 can accommodate up to about 3000 sheets (A4 size, B5 size) on which images are formed.

  FIG. 2 is a diagram illustrating the relationship between the curl direction of the paper and the loading state on the processing tray 30. On the processing tray 30, a plurality of sheets are sequentially stacked on top of each other and the trailing edge of the sheet is applied to the stopper to align the sheet in the conveying direction (also referred to as alignment). The paper is aligned in the orthogonal width direction. In the same figure, it is explanatory drawing which shows a paper state at the time of mounting the several sheet | seat from which a curl state differs on the processing tray 30. FIG.

  FIG. 2A is a diagram showing a state where a sheet bundle is created by placing a sheet with almost no curl on the processing tray 30. As shown in the figure, since the paper has almost no curl, the loaded state is good. For this reason, paper alignment can be performed accurately.

  FIG. 2B is a diagram illustrating a state in which a sheet of concave curl (also referred to as downward curl) is placed on the processing tray 30 to form a sheet bundle on the processing tray 30. As shown in the figure, it can be seen that the sheets overlapped with the processing tray 30 are uneven due to the concave curl of the sheets. Due to the concave curl, the paper floats at the front end (upper) and the rear end (lower) of the paper. This paper floating prevents the next paper entry path at the leading edge of the paper, and the paper does not reach the stopper that aligns the paper in the transport direction at the trailing edge of the paper. The problem of not being able to occur will arise.

  FIG. 2C is a diagram illustrating a state in which a sheet of convex curls (also referred to as an upward curl) is placed on the processing tray 30 to create a sheet bundle. As shown in the figure, in the case of a convex curled sheet, the sheet does not float at the leading end and the trailing end of the sheet. For this reason, the sheets can be stacked on the storage tray 30 without any problem, so that the sheet alignment is not hindered.

  In other words, regarding the alignment of the paper, there is no problem even if the paper is convexly curled as long as it is within a certain level with the paper without curling. On the other hand, in the case of concave curled paper, there is a problem in paper alignment, so even a slight curl becomes a problem.

[Curl correction device]
The configuration of the main part 10 of the curl correction apparatus will be described with reference to FIGS. FIG. 3 is a cross-sectional view of the main part 10, and FIG. 4 is a perspective view of the main part 10. The main portion 10 includes a first belt unit 11 and a second belt unit 12, and a conveyance path 100 having a correction portion is formed by both belt units, and the paper is conveyed to the conveyance path 100 to correct the curl of the paper. Perform decurling. As shown in FIG. 4, a plurality of endless belts having the same shape are arranged side by side in the paper width direction. Each endless belt has a width of several tens of millimeters, and is arranged symmetrically around the center of the sheet to be conveyed over a length corresponding to the maximum sheet passing width.

  The first belt unit 11 has rollers 111, 112, 113, 114, and 115, the second belt unit 12 has rollers 121, 122, 123, and 124, and each of the plurality of rollers has a first one. The endless belt 11B and the second endless belt 12B are stretched. N1 to N7 are curl correction sections, and each curl correction section curves the conveyance path by winding the endless belts 11B and 12B around the rollers 121, 122, 123, 124, 112, 113, and 114 facing the endless belt. A curl correction part is formed. In the main part 10, the paper is carried in from the upstream curl correction part N1 (hereinafter also referred to as introduction correction part) side and carried out from the downstream curl correction part N7.

  One end of the roller 115 of the first belt unit is connected to a drive gear (not shown), and a driving force is transmitted to the drive gear by a drive motor. The roller 111 is a movable roller, and is movable in the stretching direction with respect to the first endless belt 11B immediately before the introduction correction portion, that is, in the direction of the inner common tangent line (common inscribed line) between the roller 111 and the roller 121. A first endless belt is stretched on the roller 111 by applying a predetermined load in the inner common tangential direction and in the direction of stretching the belt. Rollers other than the roller 111 are fixed rollers.

  In addition to the roller 115, the roller 124 of the second belt unit 12 may be driven by a drive gear.

  The rollers 111 and 115 at both ends of the first belt unit and the rollers 121 and 124 at both ends of the second belt unit are drum-shaped rollers in which the diameters at both ends are smaller than the outer diameter at the center of the roller. By using a drum-shaped roller, meandering (displacement in the axial direction) of the endless belts 11B and 12B stretched around the roller can be prevented.

[Curl correction]
The curl correction force of each curl correction part N varies depending on the curved shape of the curl correction part N, and the curved shape is determined by the radius r of the roller forming the curl correction part N and the winding amount (angle) of the belt around the roller.

  The curl correction force in the curl correction units N2 to N7 excluding the introduction correction unit N1 is strongest in the curl correction unit N2 on the upstream side in the transport direction, and gradually decreases from the curl correction unit N2 toward the downstream side in the transport direction. The curl correction power of each curl correction part is set so that the That is, the curl correction force of each curl correction unit has a relationship of N2> N4> N6 and N3> N5> N7. Further, the curl correction portions are arranged so that the curl correction directions are different between adjacent curl correction portions.

  In this embodiment, the roller radius r in each curl correction unit, the winding angle of the belt around the roller, and the correction direction are set as shown in Table 1. “Up” in the correction direction is a correction direction that causes an upward curl (FIG. 2C) on the processing tray 30, and “down” is a correction direction that results in the downward curl. It is.

  Further, since the curl correction unit on the most downstream side determines the curl direction of the final sheet, in this embodiment, the curl correction direction of the curl correction unit N7 is set so as to be an upward curl. This is because the effect of the paper curl when aligning the paper bundle can be suppressed by using the upward curl as described with reference to FIG.

  In this embodiment, the curl of the paper conveyed to the curl correction device B1 is reset (destroyed) once by conveying the curl correction units N2 and N3 having the highest upstream correction force. This is presumably because a part of the fiber of the paper is destroyed by the expansion and contraction effect caused by conveying the curl correction portions N2 and N3. By resetting the curl direction of the paper and then changing the curl correction direction alternately and transporting the curl correction unit N where the curl correction force gradually decreases, the curl amount of the paper gradually converges. By passing the curl correction portion N7 having the smallest curl correction force at the end, the amount of curl and the curl direction of the paper can be controlled.

  In this embodiment, an example in which seven curl correction units N1 to N7 are provided has been described. However, the present invention is not limited to this, and five or six curl correction units or more curl correction units than seven are provided. It may be a curl correction device.

  As described above, the curl correction direction is different from that of the adjacent curl correction part, and the curl correction part has the highest curl correction force on the upstream side in the transport direction, and the curl correction part is directed downstream in the transport direction. By using a curl correction device having a conveyance path in which a curl correction unit is arranged so that the curl correction force gradually decreases, a curl correction device capable of correcting the curl without depending on the curl direction of the paper, and post-processing It is possible to obtain a curl correction device capable of transporting paper that can be accurately post-processed to the post-processing device in consideration of the characteristics of the device.

[Other Embodiments]
FIG. 5 is a diagram of a main part of a curl correction apparatus according to another embodiment. In the figure, reference numerals 131 to 135 denote curl correction units, each of which has a different correction force and direction for curl correction arranged side by side in the conveyance path. FIG. 6 is an enlarged view of one curl correction unit. The curl correction unit 13 includes rollers R1, R2, and R3 and an endless belt B that is stretched around the rollers R1 and R2. In the paper curl correction, a nip portion formed by the endless belt B and the roller R3 facing the endless belt B becomes a curl correction portion N. The curl correction is performed by conveying the paper to the curl correction unit N. The curl correction force can be changed by the radius r of the roller R3 facing the endless belt and the amount of biting (position) with respect to the endless belt.

  In the embodiment shown in FIG. 5, the curl correction unit is set so that the curl correction unit N1 on the upstream side in the sheet conveyance direction has the highest correction force. Further, the curl correction force of the curl correction part N1> correction power of the same N3> correction power of the same N5, correction power of the curl correction part N2> correction of the same N4 so that the curl correction force gradually decreases toward the downstream side in the transport direction. It is set to be power. Further, as shown in FIG. 5, the curl correction directions of adjacent curl correction parts are set to be opposite (different), and the curl correction direction of the most downstream curl correction part N5 is a convex curl on the processing tray 30. It is set to become.

1 is an overall view of an image forming system according to an embodiment of the present invention. 3 is a diagram illustrating a relationship between a curl direction of a sheet and a placement state on a processing tray 30. FIG. (A) is a sheet having no curl, (b) is a sheet having a concave curl (also referred to as a downward curl) on the processing tray 30, and (c) is a sheet having a convex curl (also referred to as an upward curl) on the processing tray 30. FIG. 6 is a diagram illustrating a state where a sheet bundle is created by placing each on a processing tray 30; It is sectional drawing of the principal part 10 of the curl correction apparatus B1. It is a perspective view of the principal part 10 of the curl correction apparatus B1. It is a figure of the principal part of the curl correction apparatus which concerns on other embodiment. It is a figure which shows one curl correction unit in the curl correction apparatus of FIG.

Explanation of symbols

A image forming apparatus B1 curl correction apparatus B2 post-processing apparatus 10 main part 11 first belt unit 12 second belt unit 13 curl correction unit N1, N2, N3, N4, N5, N6, N7 curl correction part 100 transport path 11B, 12B, B Endless belt

Claims (4)

A curl correction device for correcting curl generated on paper,
A transport path for transporting image-formed paper, comprising a transport path having a plurality of curl correction portions that curl and deform the paper to correct the curl;
The curl correction unit has a curl correction direction that is different from the adjacent curl correction unit and has the highest curl correction force on the upstream side in the conveyance direction, and extends from the curl correction unit toward the downstream side in the conveyance direction. The curl correction part is arranged so that the curl correction force gradually decreases, and
A post-processing device that performs post-processing on the image-formed paper bundle can be connected, and the curl correction direction at the curl correction unit on the most downstream side in the transport direction temporarily places the paper bundle of the post-processing device. A curl straightening device having a convex curl direction on a processing tray. A first endless belt stretched between a plurality of rollers;
A second endless belt stretched between a plurality of rollers;
Have
The conveyance path is formed by the first endless belt and the second endless belt, and the correction section is formed by winding one endless belt around a roller facing the endless belt together with the other endless belt. The curl correction apparatus according to claim 1. The curl correction force of the curl correction unit is different by changing at least one of a diameter of the counter roller and a winding angle of the endless belt around the counter roller. The curl correction apparatus as described. An image forming apparatus for forming an image on paper;
The curl correction apparatus according to any one of claims 1 to 3, wherein the curl correction is performed on a sheet on which an image is formed by the image forming apparatus.
A post-processing device that performs post-processing on paper that has been curled by the curl straightening device;
An image forming system comprising:

Images