JP2011121681A - Sheet processing device, image forming device, and sheet processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet processing device accurately aligning rear ends of sheets, an image forming device, and a sheet processing method. <P>SOLUTION: The sheet processing device 100, which is a device that performs a predetermined output processing for a conveyed sheet, includes: an end aligning means having a surface with which an end of a sheet loaded on a processing tray is in contact and a surface which presses the end of the sheet; a rear end height detecting means for detecting the height of a rear end of the sheet; a driving means for driving the end aligning means; and a controlling means 101 for controlling the driving means based on detection information detected by the rear end height detecting means and determination information in a direction of curling generated on the rear end of the sheet determined from the detection information. The controlling means 101 controls the driving means in accordance with the height of the detected rear end of the sheet and the determined direction of curling. The end aligning means is moved vertically relative to a sheet loading surface of the processing tray, so that the height between the sheet loading surface and the surface that presses the rear end of the sheet is variably controlled. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sheet processing apparatus and an image forming apparatus including the sheet processing apparatus, and more particularly to a technique for aligning the trailing ends of sheets.

  Currently, sheet processing that performs output processing such as stapling (edge binding) and punching (end holes) on sheets (paper after image formation) output from image forming apparatuses such as copy, printer, and facsimile The device is known.

  For example, in a sheet processing apparatus provided with a stapler (edge binding portion), a technique is known in which a processing tray for performing stapling is inclined and the rear end of a sheet to be processed is aligned by its own weight.

  In an apparatus provided in the apparatus instead of connecting such a sheet processing apparatus to the outside of the apparatus, the above technique cannot be adopted in order to reduce the size of the apparatus. Technology that aligns with high precision is required.

  A sheet processing apparatus provided with a stapler performs staple processing for each job after sequentially receiving and aligning sheets output after image formation. At this time, the output sheet is subjected to a fixing process in the image forming stage (passes through a fixing unit included in the image forming apparatus). For this reason, the sheet received by the sheet processing apparatus is curled by a fixing process by heat or pressure. When stapling is performed in this state, the ends of the bundled sheet bundle are uneven due to the curl.

  Therefore, for example, in Patent Document 1, for the purpose of improving sheet stacking / alignment, a curl detection unit and a sheet pull-in unit are provided on a processing tray for stacking / aligning / post-processing a sheet. A sheet processing apparatus is disclosed in which a sheet pulling unit is operated as a curl crushing unit between sheets according to a curl amount of a sheet detected by a detection unit.

However, the conventional technique has a problem that the alignment accuracy of the sheet end is poor.
For example, the sheet processing apparatus disclosed in Patent Document 1 is configured to perform predetermined control according to the detected curl amount. More specifically, it is as follows. In the sheet processing apparatus disclosed in Patent Document 1, the curl detection unit detects whether the height of the generated curl is higher or lower than a predetermined height. As a result, when the height is higher than the predetermined height, the rear end of the sheet is pressed by the pressing member, and when the height is lower than the predetermined height, the pressing member is retracted.

  As described above, in the conventional technique, in the process of aligning the trailing edge of the sheet, when the curl height is lower than a predetermined height even though the trailing edge of the sheet is curled, the generated curling is suppressed. Since the operation is not performed, it is considered that the alignment accuracy of the trailing edge of the sheet is lowered.

  In addition, the curl is different in the image forming method (for example, the difference between the “electrophotographic process method” and the “inkjet method”) and the difference in the printing surface discharge method (for example, “face-up discharge” and “face-down discharge”). ”), Etc.), the resulting direction is different. Such a difference in the curl direction is one of the causes for lowering the alignment accuracy of the trailing edge of the sheet, like the height, but this is not taken into consideration in the conventional technology.

  The present invention has been proposed in view of the above-described problems of the prior art, and an object of the present invention is to provide a sheet processing apparatus, an image forming apparatus, and a sheet processing method capable of accurately aligning the sheet trailing edge. There is.

  In order to achieve the above object, a sheet processing apparatus according to the present invention is a sheet processing apparatus that performs a predetermined output processing on a conveyed sheet, a processing tray on which the conveyed sheets are stacked, and the processing End alignment means having a surface against which the end of the sheet stacked on the tray abuts and a surface for pressing the sheet end; a rear end height detecting means for detecting the height of the rear end of the sheet; and the end Control for controlling the drive means based on drive means for driving the alignment means, detection information by the trailing edge height detection means, and determination information on the curl direction generated at the trailing edge of the sheet determined from the detection information And the control means controls the driving means according to the detected height of the trailing edge of the sheet and the determined curl direction, and the edge aligning means is placed on the sheet stacking surface of the processing tray. Perpendicular to It is dynamic, characterized by variably controlling the height between the sheet stacking surface and a surface for pressing the sheet edge.

  With such a configuration, the sheet processing apparatus according to the present invention detects the curl amount (height) of the trailing edge of the sheet and determines the generated curl direction. Based on the detection information and the determination information, the sheet processing apparatus includes a surface (sheet end contact surface) on which a sheet end stacked on the processing tray contacts and a surface (sheet end pressing surface) that presses the sheet end. The provided end aligning means is moved vertically (moved up and down) with respect to the sheet stacking surface of the processing tray to variably control the height (opening amount) between the sheet stacking surface and the sheet end pressing surface. .

  Accordingly, the sheet processing apparatus according to the present invention can align the trailing edges of the sheets with high accuracy.

  In order to achieve the above object, a sheet processing method according to the present invention is a sheet processing method in a sheet processing apparatus that performs a predetermined output processing process on a conveyed sheet, wherein the height of the trailing edge of the conveyed sheet is high. A rear end height detection procedure for detecting the height, and an end alignment portion having a surface with which the end of the sheet stacked on the processing tray abuts and a surface for pressing the end of the sheet, according to the rear end height detection procedure. A surface that moves perpendicularly to the sheet stacking surface of the processing tray and presses the sheet stacking surface and the sheet end in accordance with the detected height of the sheet trailing edge and the curl direction generated at the sheet trailing edge. And a control procedure for variably controlling the height between them.

  By such a procedure, the sheet processing method according to the present invention detects the curl amount (height) of the sheet rear end in the process of aligning the sheet rear end, determines the generated curl direction, and detects the detection information and Based on the determination information, an operation of variably controlling the height (opening amount) between the sheet stacking surface of the processing tray and the sheet end pressing surface of the end aligning unit is realized.

  As a result, the sheet processing method according to the present invention can provide a sheet processing mechanism capable of aligning the trailing edge of the sheet with high accuracy.

  According to the present invention, in the process of aligning the sheet trailing edge, based on the detected curl amount (height) and the determined curl direction, the sheet stacking surface of the processing tray and the sheet edge pressing surface of the edge aligning portion By making the height (opening amount) variably controllable, it is possible to provide a sheet processing apparatus, an image forming apparatus, and a sheet processing method that can accurately align the sheet trailing edge.

FIG. 2 is a diagram illustrating a hardware configuration example of a sheet processing apparatus according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a configuration example of a sheet trailing edge alignment mechanism included in the sheet processing apparatus according to the first exemplary embodiment of the present invention. It is a figure which shows an example of the rear-end height detection sensor which concerns on the 1st Embodiment of this invention. It is a figure which shows the operation example which detects the height of the upward curl (face curl) which arose in the sheet | seat rear end which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of a method of determining the upward curl (face curl) which arose in the sheet | seat rear end which concerns on the 1st Embodiment of this invention. It is a figure which shows the operation example which detects the height of the downward curl (back curl) which arose in the sheet | seat rear end which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of a method which determines the downward curl (back curl) which arose in the sheet | seat rear end which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of the sheet | seat trailing edge alignment function which concerns on the 1st Embodiment of this invention. 5 is a flowchart illustrating an example of a sheet processing procedure including a sheet trailing edge alignment process according to the first embodiment of the present invention. 6 is a flowchart illustrating an example of a processing procedure for determining a curl direction generated at a trailing edge of a sheet according to the first embodiment of the present invention. 6 is a flowchart illustrating an example of a processing procedure for determining an opening amount when an upward curl (face curl) occurs at the rear end of a sheet according to the first embodiment of the present invention. FIG. 10 is a diagram illustrating an operation example (part 1) for aligning the trailing edge of the sheet according to the first exemplary embodiment of the present invention. An example of an operation in which the processing tray according to the first embodiment of the present invention varies the height (opening amount) between a sheet stacking surface (sheet stacking surface) and a sheet pressing surface (pressing surface). FIG. It is a figure which shows the operation example (the 2) which aligns the sheet | seat rear end which concerns on the 1st Embodiment of this invention. It is a figure which shows the operation example of the sheet process which concerns on the 1st Embodiment of this invention. 10 is a flowchart illustrating an example of a sheet processing procedure including a sheet trailing edge alignment process according to the second embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings.

[First Embodiment]
<Hardware configuration>
FIG. 1 is a diagram illustrating a hardware configuration example of a sheet processing apparatus 100 according to the present embodiment.
FIG. 1 is a cross-sectional view illustrating a schematic configuration example of the sheet processing apparatus 100. As shown in FIG. 1, the sheet processing apparatus 100 sandwiches and conveys the sheet s by a conveyance roller pair 1 including a driving roller and a driven roller driven by a conveyance motor (not shown).

  The sheet s detected by the entrance sensor 8 and conveyed onto the processing tray 4 has a sheet end (hereinafter referred to as “sheet rear end”) serving as a rear end in the conveyance direction, and is therefore conveyed in the conveyance direction by the leading roller 2a. It is conveyed in the direction of the end stopper 5a opposite to the above. At this time, the sheet shifting arm 2 rotates around the support shaft 2b by turning on and off a drive solenoid (not shown) in order to bring the leading roller 2a into contact with the sheet s.

  The end stopper 5a is an end aligning means, and includes a pressing surface (sheet end pressing surface) 5b that presses the end of the sheet conveyed to a contact position (sheet end contacting surface). The tip of the pressing surface 5b has a smooth shape in order to smoothly guide the curl generated at the sheet end. Furthermore, the pressing surface 5b includes, for example, a pressing member 6 that is an elastic member such as a leaf spring, and when the subsequent sheet is received, the end stopper 5a is opened, that is, the sheet stacking surface of the processing tray 4 The sheet end portion can be pressed even if the distance between the sheet and the pressing surface 5b of the end stopper 5a is a predetermined height (predetermined opening amount). Thereby, even when the end stopper 5a is opened, it is possible to prevent rear end alignment failure due to curling.

  Further, the end stopper 5a includes a control motor 7 that drives the pressing surface 5b up and down. In front of the end stopper 5a, when the sheet s is conveyed to the end stopper 5a by the front end roller 2a, the rear end height detection sensor 11 (rear end height detection) detects the height of the rear end of the sheet. Means). Accordingly, the end stopper 5a moves the pressing surface 5b up and down (perpendicular to the sheet stacking surface) based on the detection information, and the height (between the sheet stacking surface and the pressing surface 5b of the processing tray 4). Control the amount of opening.

  Here, a configuration example of the sheet rear end alignment mechanism including the end stopper 5a, the control motor 7, and the rear end height detection sensor 11 will be described.

FIG. 2 is a diagram illustrating a configuration example of a sheet trailing edge alignment mechanism provided in the sheet processing apparatus 100 according to the present embodiment.
In the configuration example shown in FIG. 2, the end stoppers 5a are arranged at two locations. In this case, the driving force is transmitted to the end stopper 5a with the following configuration. For example, the control motor 7 such as a stepping motor is provided with a gear 7a, the shaft 12 has a gear 12a ₁ interlocked meshed with the gear 7a. Furthermore, the shaft 12 includes gears 12a ₂ and 12a ₃ that transmit driving force to the end stopper 5a. With this configuration, the end stopper 5a can be moved up and down, and the sheet end can be pressed at a plurality of locations, so that the alignment accuracy (alignment accuracy) of the sheet rear end is improved.

  The arrangement of the end stopper 5a is, for example, a position that avoids a binding position (binding position) by a stapler (not shown) that performs stapling. Further, as long as the binding position is avoided, the end stopper 5a may be arranged at two or more locations. Further, by using a stepping motor as the control motor 7, the end stopper 5a can be moved more vertically. That is, the height (opening amount) between the sheet stacking surface and the pressing surface 5b can be varied more finely. Thus, by using a stepping motor capable of pulse control for the control motor 7, fine control becomes possible, and the alignment accuracy (alignment accuracy) of the sheet trailing edge is improved.

  FIG. 2A shows an example in which the rear end height detection sensor 11 is arranged at one place. On the other hand, FIG. 2 (B) shows an example of arrangement at two locations. As shown in FIG. 2 (B), when the rear end height detection sensor 11 is arranged in two places, for example, based on the comparison result of two detection information obtained from the rear end height detection sensor 11, The height (opening amount) between the sheet stacking surface and the pressing surface 5b may be varied.

  Returning to the description of FIG. When the sheets s having the aligned end portions are bundled in a predetermined number on the processing tray 4, the requested sheet processing (for example, “staple processing”) is performed. The processed sheet bundle is sandwiched between a paper discharge roller 3 a driven by a paper discharge motor (not shown) and a paper discharge driven roller 3 b that moves up and down by an opening solenoid (not shown) to the paper discharge tray 9. Be transported.

  Note that the side aligning member 10 shown in FIG. 1 is a member that can move in the lateral direction perpendicular to the conveying direction of the sheet s and aligns the right end and the left end of the sheet end. On the other hand, the main part according to the present embodiment aligns the rear end of the sheet for performing sheet processing, and the processing for aligning the side aligning member 10 with the right and left ends of the sheet is omitted in the following description.

Next, details (installation position, configuration, and members) of the rear end height detection sensor 11 will be described.
FIG. 3 is a diagram illustrating an example of the rear end height detection sensor 11 according to the present embodiment.

"Installation position"
As shown in FIG. 3A, the rear end height detection sensor 11 is installed between the end stopper 5a and the paper discharge driven roller 3b so as not to come into contact with the sheet shifting arm 2 at the time of activation. .

"Constitution"
As shown in FIG. 3B, the rear end height detection sensor 11 includes a sensor 11a, a disk 11b, a shaft 11c, a pendulum 11d, a stopper 11e, and the like.

  The pendulum 11d rotates in one direction (counterclockwise in this embodiment) about the shaft 11c by contact with the sheet s (see the white arrow in the figure). The stopper 11e is provided so that the pendulum 11d does not rotate in the reverse direction (clockwise in this embodiment).

  The disc 11b is provided with an equiangular slit and is integrated with the pendulum 11d. Further, the disk 11b is not integrated with the shaft 11c and rotates by the rotation of the pendulum 11d. That is, the disk 11b rotates in conjunction with the rotation of the pendulum 11d due to contact with the sheet s.

  The sensor 11a is a transmission type sensor and detects the slit of the disk 11b. For example, as shown in FIG. 3D, the sensor 11a may be a reflective sensor as long as it is a disk 11b in which black and white are alternately applied instead of slits.

  Further, the pendulum 11d shown in FIG. 3B is provided so as to be perpendicular to the sheet stacking surface of the processing tray 4. For example, as shown in FIG. Instead of being perpendicular to the sheet stacking surface, a certain angle may be provided. In this case, since it does not rotate in the reverse direction, the stopper 11e becomes unnecessary.

"Element"
As a member of the pendulum 11d provided in the rear end height detection sensor 11, a light resin material that does not apply a load to the sheet s is preferable because the pendulum 11d contacts the sheet s. Further, in the rear end height detection sensor 11, if the pendulum 11d is deformed at the time of sheet contact, the height of the rear end of the sheet may be erroneously detected. Therefore, it is necessary to use a member having a thickness that does not deform. .

<Curl height detection / curl direction determination method>
The trailing edge height detection sensor 11 detects the height of the trailing edge of the sheet (the height of the curl) based on the arrangement position and the configuration, and the sheet processing apparatus 100 generates the trailing edge based on the result. Determine the curl direction. In the following, each characteristic in the curl direction (upward curl / downward curl) will be described.

"Upward curl: Face curl"
FIG. 4 is a diagram illustrating an operation example of detecting the height of the upward curl (face curl) generated at the rear end of the sheet according to the present embodiment.
FIG. 4 shows stepwise operations of conveying the sheet s on the processing tray 4 to the sheet end contact surface of the end stopper 5a by the front end roller 2a. Specifically, FIG. 4A shows a stage [1] in which the sheet s comes into contact with the pendulum 11d, and FIG. 4B shows that the pendulum 11d moves to a height at the end of the sheet as the sheet s moves after the contact. The stage [2] is shown to be pushed up. Subsequently, in FIG. 4C, the stage where the pendulum 11d is pushed back to the original position [3], and in FIG. 4D, the stage where the pendulum 11d is returned to the original position [4]. It is shown.

  As can be seen from the operation examples of the above steps [1] to [4], in the trailing edge height detection sensor 11, the pendulum 11d rotates to the height of the sheet edge by the contact of the sheet s, and the sheet trailing edge. Return to original position after passing. The rear end height detection sensor 11 detects the rotation of the disk 11b during the upward curl (face curl) by the sensor 11a from the characteristics when such upward curl (face curl) occurs. At this time, the sensor 11a detects the rotation of the disk 11b by, for example, pulse counting. In the case of upward curl (face curl), the pulse generation changes as shown in FIG. 4E in each of steps [1] to [4].

  FIG. 4E shows the state of the output pulse by the sensor 11a in each of the steps [1] to [4]. The vertical axis is height [H], and the horizontal axis is time [t].

  For example, the height displacement amount at the time interval [Δt1] is [ΔH1], and the height displacement amount at the time interval [Δt2] is [ΔH2]. Furthermore, ΔH1 <ΔH2 is established in the magnitude relationship between the displacement amount [ΔH1] and the displacement amount [ΔH2]. From this, the pulse interval of the output pulse from the stage [1] to [2] gradually becomes narrower from the stage [1] to [2].

  Further, the displacement amount of the height at the time interval [Δt3] is [ΔH3], and ΔH2> ΔH3 is established in the magnitude relationship between the displacement amount [ΔH2] and the displacement amount [ΔH3]. From this, the output pulse gradually becomes wider as the inflection point of the stage [2] approaches after the pulse interval becomes gradually narrower during the stage [1] to [2].

  When the inflection point of stage [2] is passed, stage [3] is reached, and the pendulum 11d tries to return to the original position, so that the amount of displacement in height changes greatly and the pulse interval narrows rapidly.

  In stage [4], the pendulum 11d returns to its original position. In the meantime, the pendulum 11d increases and decreases in pulse interval due to vibration caused by swinging back, but the height displacement amount disappears and the pulse output gradually disappears.

  Thus, when the upward curl (face curl) occurs at the rear end of the sheet, the detection information (output pulse) of the pulse characteristics as described above is obtained from the rear end height detection sensor 11.

FIG. 5 is a diagram illustrating an example of a method for determining an upward curl (face curl) generated at the rear end of the sheet according to the present embodiment.
In the sheet processing apparatus 100, a calculation process of differential value calculation is performed on the detection information, and the curl direction is determined based on the calculation result.

  The upper part of FIG. 5 shows the output pulse shown in FIG. 4E, and the lower part shows the differential value [dH / dt] of the output pulse. For example, the following characteristics can be seen from the change in the differential value [dH / dt] shown in FIG. The differential value [dH / dt] is obtained from the stage [1] of the time [t0] (immediately after sensor input) when the height detection is started to the stage [1] of the time [tm] (during passage of the rear end of the sheet). Compared with the change up to 2], the change from stage [2] to stage [3], which is the inflection point, is large. That is, a change in the pulse interval output when the pendulum 11d returns from the maximum height to the original position, which is one of the characteristics of the upward curl (face curl), appears in the change of the differential value [dH / dt]. ing. In the upward curl (face curl), the differential value [dH / dt] changes most significantly after the time [tm] when the maximum height is detected (a peak appears).

  Accordingly, the sheet processing apparatus 100 can determine that the curl generated at the trailing edge of the sheet is upward from the variation characteristic of the differential value [dH / dt]. Specifically, the amount of change in the differential value [dH / dt] within a predetermined time and the magnitude relationship between a preset threshold value (determination value [m]) are compared, and the time when the maximum height is detected If the amount of change up to [tm] is smaller than the threshold, it is determined that the curl is upward (face curl). The “threshold value” is a determination value for determining whether or not the change amount of the differential value [dH / dt] exceeds a certain change amount.

<< downward curl: back curl >>
FIG. 6 is a diagram illustrating an operation example for detecting the height of the downward curl (back curl) generated at the rear end of the sheet according to the present embodiment.
FIG. 6 shows stepwise operations similar to those in FIG. Specifically, FIG. 6A shows the stage [1] in which the sheet s comes into contact with the pendulum 11d [1], and FIG. 6B shows that the pendulum 11d has a height at the end of the sheet as the sheet s moves after the contact. FIG. 6C shows a stage [3] in which the sheet s is conveyed to the sheet end contact surface of the end stopper 5a with the pendulum 11d being pushed up. ing.

  As can be seen from the operation examples of the above steps [1] to [3], in the trailing edge height detection sensor 11, the pendulum 11d rotates to the height of the sheet edge by the contact of the sheet s. Even after passing, it does not return to its original position and is kept pushed up. The rear-end height detection sensor 11 detects the rotation of the disk 11b during the downward curl (back curl) from the characteristic of such a downward curl (back curl). At this time, the sensor 11a detects the rotation of the disk 11b by, for example, pulse counting. In the case of a downward curl (back curl), the pulse generation changes as shown in FIG. 6E in each step [1] to [3].

  FIG. 6E shows the state of output pulses by the sensor 11a in each of the above steps [1] to [3]. The vertical axis is height [H], and the horizontal axis is time [t].

  For example, the height displacement amount at the time interval [Δt1] is [ΔH1], and the height displacement amount at the time interval [Δt2] is [ΔH2]. Furthermore, ΔH1> ΔH2 is established in the magnitude relationship between the displacement amount [ΔH1] and the displacement amount [ΔH2]. From this, the pulse interval of the output pulses from stage [1] to [2] gradually increases from stage [1] to [2].

  Further, after step [2], step [3] is reached, and the position of the pendulum 11d changes at substantially the same position as the height of the rear end of the sheet, so that the amount of displacement of the height is small and the pulse interval is further widened.

  Thus, when the downward curl (back curl) occurs at the rear end of the sheet, the detection information (output pulse) of the pulse characteristics as described above is obtained from the rear end height detection sensor 11.

FIG. 7 is a diagram illustrating an example of a method for determining a downward curl (back curl) generated at the rear end of the sheet according to the present embodiment.
In the sheet processing apparatus 100, a calculation process of differential value calculation is performed on the detection information, and the curl direction is determined based on the calculation result.

  The upper part of FIG. 7 shows the output pulse shown in FIG. 6E, and the lower part shows the differential value [dH / dt] of the output pulse. For example, the following characteristics can be seen from the change in the differential value [dH / dt] shown in FIG. The differential value [dH / dt] is the stage at the time [t0] when the height detection is started, compared with the change of the time [tm] at which the maximum height is detected through the stage [2] up to the stage [3]. [1] The change in the vicinity is large. That is, a change in the pulse interval output when the pendulum 11d is pushed up from the original position to the maximum height, which is one of the characteristics of the downward curl (back curl), is a change in the differential value [dH / dt]. Appears. In the downward curl (back curl), the differential value [dH / dt] changes the most (peak value appears) before the time [tm] when the maximum height is detected.

  As a result, the sheet processing apparatus 100 can determine from the fluctuation characteristic of the differential value [dH / dt] that the curl generated at the trailing edge of the sheet is downward. Specifically, the amount of change in the differential value [dH / dt] within a predetermined time and the magnitude relationship between a preset threshold value (determination value [m]) are compared, and the time when the maximum height is detected If the amount of change up to [tm] is larger than the threshold value, it is determined that the curl is downward curl (back curl).

  As described above, in the sheet processing apparatus 100, based on the pulse count output from the trailing edge height detection sensor 11, the sheet processing apparatus 100 does not depend on the difference in the image forming method or the discharge method of the printing surface. Edge height detection and curl direction can be determined.

<Seat trailing edge alignment function>
From here, the sheet trailing edge alignment function according to the present embodiment will be described.
In the sheet processing apparatus 100 according to the present embodiment, the curl amount (height) of the trailing edge of the sheet is detected, and the generated curl direction is determined. The sheet processing apparatus 100 includes an end provided with a surface (sheet end contact surface) on which a sheet end stacked on the processing tray 4 abuts and a pressing surface 5b for pressing the sheet end based on detection information and determination information. The part stopper 5a (end alignment means) is moved vertically (moved up and down) with respect to the sheet stacking surface of the processing tray 4, and the height between the sheet stacking surface and the pressing surface 5b of the end stopper 5a ( The opening amount is variably controlled. The sheet processing apparatus 100 has such a sheet rear end alignment function.

  For example, in a conventional apparatus, the curl detection means detects whether the height of the curl generated is higher or lower than a predetermined height, and when it is higher than the predetermined height, the sheet trailing edge is pressed by a pressing member, When it is lower than the height, the pressing member is retracted.

  As described above, according to the conventional technique, in the process of aligning the sheet trailing edge, the curling is not performed unless curling of a predetermined height or more is generated at the sheet trailing edge. It is conceivable that the accuracy will drop. Further, in the conventional technique, the curl direction, which is one of the causes for reducing the alignment accuracy, is not considered.

  Therefore, in the sheet processing apparatus 100 according to the present embodiment, in the process of aligning the sheet trailing edge, the amount of curling at the sheet trailing edge is detected, the generated curl direction is determined, and the processing is performed based on the detection information and the determination information. The height (opening amount) between the sheet stacking surface of the tray 4 and the pressing surface 5b of the end stopper 5a is variably controlled.

  As a result, the sheet processing apparatus 100 according to the present embodiment can align the trailing edges of the sheets with high accuracy.

The configuration and operation of the sheet trailing edge alignment function will be described below.
FIG. 8 is a diagram illustrating a configuration example of the sheet trailing edge alignment function according to the present embodiment.
As illustrated in FIG. 8, the sheet processing apparatus 100 includes a control unit 101, a detection unit 102, a drive unit 103, and the like.

  The control unit 101 is a functional unit that controls the operation of the sheet processing apparatus 100. The control unit 101 is a function of, for example, a CPU (Central Processing Unit).

  The detection unit 102 is a functional unit that detects various control values used during operation control of the sheet processing apparatus 100. The detection unit 102 is a function of the inlet sensor 8 and the rear end height detection sensor 11 described above, for example.

  The driving unit 103 is a functional unit that drives each unit to operate the sheet processing apparatus 100. The drive unit 103 is a function of, for example, the transport motor (not shown), the drive solenoid (not shown), the control motor 7, the paper discharge motor (not shown), and the opening solenoid (not shown) described above.

  In the sheet processing apparatus 100, the control unit 101 receives control information (for example, “staple processing execution request”) from the control unit 201 included in the image forming apparatus (high-level apparatus) 200 that sends the processing target sheet s to the apparatus. Based on the control signal). Subsequently, the sheet processing apparatus 100 acquires detection information (for example, a detection signal such as “passage of the sheet trailing edge” or “height of the sheet edge”) from the detection unit 102 and drives based on the acquired detection information. The unit 103 is controlled. Thus, in the sheet processing apparatus 100, the operation of the entire apparatus is controlled, and the sheet processing requested from the image forming apparatus 200 is performed. Further, in the sheet processing apparatus 100, the control unit 101 performs predetermined calculation processing on the detection information corresponding to the height of the sheet end acquired from the detection unit 102, determines the curl direction generated at the trailing end of the sheet, Based on the determination result, the drive unit 103 is controlled.

  As described above, the sheet trailing edge alignment function according to the present embodiment is realized by the above-described functional units operating in conjunction with each other.

  Next, a detailed operation of the sheet trailing edge alignment function (operational function group linkage operation) will be described with reference to a flowchart showing a processing procedure.

  As described above, the sheet trailing edge alignment function is realized by executing the following processing by the control unit 101 (for example, “CPU”) installed in the sheet processing apparatus 100.

  FIG. 9 is a flowchart illustrating an example of a sheet processing procedure including a sheet trailing edge alignment process according to the present embodiment. FIG. 9 shows an example of a processing procedure when a staple process is requested from the image forming apparatus 200 corresponding to the host apparatus to the sheet processing apparatus 100.

  In the following description, a specific operation example of the sheet processing apparatus 100 in the processing procedure will also be described with reference to FIGS. FIG. 12 is a diagram illustrating an operation example (No. 1) for aligning the sheet trailing edge according to the present embodiment. FIG. 13 also shows that the height (opening amount) between the surface (sheet stacking surface) on which the processing tray 4 according to this embodiment stacks the sheets s1 and the surface (pressing surface 5b) that presses the end of the sheet is variable. It is a figure which shows the operation example to do. FIG. 14 is a diagram illustrating an operation example (part 2) for aligning the sheet trailing edge according to the present embodiment. FIG. 15 is a diagram illustrating an operation example of sheet processing according to the present embodiment.

  In the sheet processing apparatus 100 according to the present embodiment, after the control unit 101 included in the apparatus acquires sheet information (for example, “sheet thickness” and “number of bundles”) from the control unit 201 included in the image forming apparatus 200. (Step S1), preparation for receiving the sheet s is executed.

  The control unit 101 controls the driving unit 103 as follows as preparation for acceptance. The control unit 101 turns on an opening solenoid (not shown) of the paper discharge driven roller 3b (step S2), and raises the paper discharge driven roller 3b to the position shown in FIG. Subsequently, the control unit 101 drives a conveyance motor (not shown) (step S3), and rotates the conveyance roller pair 1 in the conveyance direction of the sheet s. Further, the control unit 101 turns on a drive solenoid (not shown) of the sheet shifting arm 2 (step S4), and raises the sheet shifting arm 2 to the position shown in FIG. When these controls are completed, the control unit 101 transmits a sheet conveyance permission signal to the control unit 201 included in the image forming apparatus 200 (step S5). As a result, the image forming apparatus 200 starts conveying the sheet s to the sheet processing apparatus 100.

  In the sheet processing apparatus 100, the sheet s conveyed from the image forming apparatus 200 is sandwiched between the conveyance roller pair 1 (drive roller and driven roller) and conveyed onto the processing tray 4. At this time, the control unit 101 controls the drive unit 103 as follows based on the detection information from the detection unit 102. The control unit 101 detects the passage of the rear end of the sheet by the inlet sensor 8, and after a predetermined time has elapsed (step S6: YES), the drive solenoid (not shown) of the sheet shifting arm 2 is turned off (step S7).

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the sheet moving arm 2 is lowered by its own weight, presses the upper surface of the conveyed sheet s1, and the sheet s1 comes into contact with the processing tray 4.

  Returning to the description of FIG. Thereafter, the control unit 101 transmits a sheet conveyance prohibition signal to the control unit 201 included in the image forming apparatus 200 (step S8), and stops a conveyance motor (not shown) (step S9).

  Subsequently, in the sheet processing apparatus 100, the control unit 101 performs drive control based on the detection information from the detection unit 102, whereby the sheet rear end alignment process as illustrated in FIGS. 12B and 12C is performed. Done.

  Returning to the description of FIG. First, when the conveyed sheet s is the first sheet of a bundle (step S10: YES), the control unit 101 sets the height (opening amount) between the sheet stacking surface and the pressing surface 5b. Is driven to a predetermined height [h0] (step S11). Further, the control unit 101 rotates the tip roller 2a of the sheet shifting arm 2 by a predetermined amount counterclockwise (step S12).

  Meanwhile, the trailing edge height detection sensor 11 serving as the detection unit 102 detects the height of the trailing edge of the sheet by moving the sheet s1 toward the sheet edge contact surface of the edge stopper 5a. As a result, detection information (sheet rear end height: curl amount generated at the rear end) is passed from the rear end height detection sensor 11 to the control unit 101.

  Based on the received detection information, the control unit 101 variably controls the height (opening amount) between the sheet stacking surface and the pressing surface 5b as follows.

  First, the control unit 101 determines the curl direction generated at the trailing edge of the sheet based on the detection information (step S13).

  Hereinafter, the curl direction determination process performed by the control unit 101 will be described with reference to FIG.

FIG. 10 is a flowchart illustrating an example of a processing procedure for determining the curl direction generated at the trailing edge of the sheet according to the present embodiment.
The control unit 101 determines whether or not there is an input fluctuation by the rear end height detection sensor 11 (step S400), and when there is an input fluctuation (step S400: YES), a differential value with respect to the detection signal (output pulse). Calculation of [dH / dt] is started (step S401).

  The control unit 101 differentiates the differential value [dH / dt] calculated at each time [t] from the time [t0] at which the height detection is started to the time [tm] at which the maximum height is detected. A value [dH / dt] is acquired (step S402). That is, in the control unit 101, the height displacement amount [H] from when the trailing edge height detection sensor 11 starts height detection until the trailing edge of the sheet passes is differentially calculated, and the differential value [dH / dt]. To get.

  The control unit 101 determines whether or not the acquired differential value [dH / dt] is larger than a preset threshold value (determination value [m]) (step S403). As described above, the characteristic in the curl direction appears in the differential value [dH / dt] from when the trailing edge height detection sensor 11 starts height detection until the trailing edge of the sheet passes. Specifically, in the case of downward curl (back curl), the maximum (peak) of the differential value [dH / dt] appears between the start of height detection and the passage of the trailing edge of the sheet. On the other hand, in the case of upward curl (face curl), it does not appear. From such characteristics, the control unit 101 determines the curl direction as follows.

  When the control unit 101 determines that the acquired differential value [dH / dt] is larger than the threshold value (step S403: YES), the maximum (peak) of the differential value [dH / dt] appears within the above time. Therefore, it is determined that the generated curl is a downward curl (back curl). As a result, the control unit 101 sets “0” in the determination flag R (step S404).

  On the other hand, when it is determined that the obtained differential value [dH / dt] is smaller than (or equal to) the threshold value (step S403: NO), since it does not appear within the above time, the generated curl is an upward curl (face curl). ). As a result, the control unit 101 sets “1” in the determination flag R (step S405).

  Returning to the description of FIG. When the control unit 101 determines that the curl is downward curl (back curl) from the determination result (the bit value of the determination flag) (step S13: YES), the height (opening amount) between the sheet stacking surface and the pressing surface 5b is determined. ) Drives the control motor 7 of the end stopper 5a so that [h1] becomes [h1] (step S14). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is lowered from the height [h0] to [h1].

  On the other hand, when the control unit 101 determines that the curl is upward (face curl) from the determination result (the bit value of the determination flag) (step S13: NO), the control unit 101 performs the following process.

  Hereinafter, the opening amount determination process at the time of upward curling (face curling) performed by the control unit 101 will be described with reference to FIG.

FIG. 11 is a flowchart illustrating an example of a processing procedure for determining an opening amount when an upward curl (face curl) occurs at the trailing edge of the sheet according to the present embodiment.
The control unit 101 determines whether or not the detected height [Hc] of the trailing edge of the sheet is equal to or lower than a predetermined height [h1] (step S300).

  When the detected height [Hc] of the trailing edge of the sheet is equal to or less than the predetermined height [h1] (step S300: YES), the control unit 101 determines the height between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the (opening amount) becomes [h1] (step S301). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is lowered from the height [h0] to [h1].

  When the detected height [Hc] of the trailing edge of the sheet is higher than the predetermined height [h1] (step S300: NO), the control unit 101 determines that the detected height [Hc] of the trailing edge of the sheet is predetermined. It is determined whether it is below [h2] (step S302).

  When the detected height [Hc] of the trailing edge of the sheet is equal to or less than the predetermined height [h2] (step S302: YES), the control unit 101 determines the height between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the (opening amount) becomes [h2] (step S303). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is lowered from the height [h0] to [h2].

  Further, when the detected height [Hc] of the trailing edge of the sheet is higher than the predetermined height [h2] (step S302: NO), the control unit 101 determines that the detected height [Hc] of the trailing edge of the sheet is predetermined. It is determined whether the height is [h3] or less (step S304).

  When the detected height [Hc] of the trailing edge of the sheet is equal to or lower than the predetermined height [h3] (step S304: YES), the control unit 101 determines the height between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the (opening amount) becomes [h3] (step S305). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is lowered from the height [h0] to [h3].

  The “predetermined heights [h0], [h1], [h2], and [h3]” are for variably controlling the height (opening amount) between the sheet stacking surface and the pressing surface 5b. These are a plurality of control values set in stages. The magnitude relationship between the predetermined heights [h0], [h1], [h2], and [h3] is [h1] <[h2] <[h3] <[h0].

  As described above, the sheet processing apparatus 100 does not determine the opening amount of the end stopper 5a based on one control value (the reference height to be controlled), but uses a plurality of control values to detect the detected height of the trailing edge of the sheet. The opening amount of the end stopper 5a is varied according to the curl amount generated at the rear end and the determined curl direction.

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the curl generated at the trailing edge of the sheet is reliably inserted between the sheet stacking surface and the pressing surface 5b.

  Returning to the description of FIG. Thereafter, the control unit 101 drives the control motor 7 of the end stopper 5a so that the height (opening amount) between the sheet stacking surface and the pressing surface 5b becomes the calculated value of the formula [hs + x × n]. (Step S15). [Hs] is a value in a range of 0 ≦ [hs] ≦ [h1], and is a value indicating a height at which the sheet bundle stacked on the processing tray 4 is not damaged and the sheet bundle can be held. It is. [X] and [n] are values based on the sheet information acquired in step S1. [X] is a value indicating the thickness of the paper, and [n] is a value indicating the number of bound sheets.

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the pressing surface 5b is lowered to the height calculated by the equation [hs + x × n], and the curl generated at the rear end of the conveyed sheet s1 is sandwiched. That is, the rear end of the sheet s is pressed at a height [h1] or less. The reason for controlling to such a height is to suppress the sheet s so that the sheet s is not disturbed when the subsequent sheet is brought into contact with the processing tray 4 after receiving the sheet s in addition to curling suppression.

Here, the sheet trailing edge alignment process described above will be described in detail with reference to FIG.
The height of the pressing surface 5b (the height (opening amount) between the sheet stacking surface and the pressing surface 5b) is the height shown in FIG. 13A before detecting the height of the trailing edge of the first sheet. It is located at [h0] and varies according to the detected height [Hc]. In the above processing example, the height of the pressing surface 5b is variable in three stages, but this is not restrictive. The number of stages can be increased or decreased according to the device performance.

  Next, taking the above-described three-stage variable control as an example, the heights [h1], [h2], [h3] that are control values of the pressing surface 5b and the height of the rear end height detection sensor 11 at the disk 11b. A method of determining the detection region (slit or applied black and white angle θr) will be described with reference to FIGS. 13B, 13C, 13D, and 13E.

《Determination of control value to control height》
For example, the heights [h1], [h2], and [h3] are determined as follows. First, the curl height (assumed curl amount) that is expected to occur at the rear end of the sheet is set to the maximum control value in the product standard, that is, the highest height [h3] among the three-stage variable control. Subsequently, based on the determined height [h3], the heights [h2] and [h1] of the control values corresponding to the remaining stages are determined. Specifically, the height [h2] is a calculated value of the equation [h3 × (3/4)], and the height [h1] is a calculated value of the equation [h3 × (1/2)]. As a result, the above-described magnitude relationship is established in the heights [h1], [h2], and [h3].

《Determination method of height detection division area (angle) in disk》
For example, the rotation angle θ of the disk 11b when the pendulum 11d rotates can be expressed by the equation [cos θ = (H−Hc) / H]. As a result, the rotation angles θ ₁ , θ ₂ , θ ₃ corresponding to each stage substitute the height [h1], [h2], [h3] of the control value at each stage for the variable [Hc], and the axis 11c The height [H] from the sheet stacking surface to the sheet stacking surface can be determined. At this time, the value of the height [H] from the shaft 11c to the sheet stacking surface is determined in consideration of the size of the disk 11b so that the curl expected to occur at the rear end of the sheet does not contact the disk 11b. It determines so that it may become more than height [h3].

The height detection divided region in the disk 11b, that is, the angle θr of the slit (or applied black and white) in the disk 11b is determined based on the rotation angle corresponding to each of the above steps. Specifically, the angle θr is set to a value that satisfies the condition [θ ₂ −θ ₁ > θr].

  As described above, the height detection divided area (angle θr) in the disk 11b can increase the number of steps in the variable control by reducing the range of the divided area (value of the angle θr).

  In the above-described alignment processing of the trailing edge of the sheet, the example in which the trailing edge height detection sensor 11 that detects the movement of the member (pendulum 11d) in contact with the sheet s is used as the detection unit 102 has been described. . For example, the rear end height detection sensor 11 including a reflection type sensor that outputs an analog signal according to the distance from the sheet s is disposed on the upper portion of the processing tray 4 (the position of the disk 11b). A method of detecting the height of the end may be used.

  Returning to the description of FIG. In the sheet processing apparatus 100, when the sheet s is the second and subsequent sheets of the bundle (step S10: NO), the height of the trailing edge of the sheet is not detected, and drive control is performed by the control unit 101, so that FIG. ), (B), and (C) as shown in FIG.

  The control unit 101 drives the control motor 7 of the end stopper 5a until the succeeding sheet s2 is conveyed and placed on the processing tray 4.

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the end of the sheet s1 already stacked is pressed by the pressing surface 5b of the end stopper 5a.

  Returning to the description of FIG. The control unit 101 stops the conveyance motor (not shown), and the value [x] indicating the thickness of the sheet at the height (opening amount) between the sheet stacking surface and the pressing surface 5b determined for the first sheet. Then, the control motor 7 of the end stopper 5a is driven based on a value obtained by multiplying the value [n] indicating the number of bundles.

  The control unit 101 determines whether or not the height [Hc] of the trailing edge of the sheet detected in the first sheet is equal to or less than a predetermined height [h1] (step S17).

  When the detected height [Hc] of the trailing edge of the sheet is equal to or less than the predetermined height [h1] (step S17: YES), the control unit 101 determines the height between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the opening amount becomes the calculated value of the equation [h1 + x × n] (step S18). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is raised from the height of the calculated value of the formula [hs + x × n] to the height of the calculated value of the formula [h1 + xx × n].

  Further, when the height [Hc] of the sheet trailing edge detected in the first sheet is higher than the predetermined height [h1] (step S17: NO), the control unit 101 detects the detected height of the sheet trailing edge. It is determined whether [Hc] is equal to or lower than a predetermined height [h2] (step S19).

  When the detected height [Hc] of the trailing edge of the sheet is equal to or less than the predetermined height [h2] (step S19: YES), the control unit 101 determines the height between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the opening amount becomes the calculated value of the equation [h2 + x × n] (step S20). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is raised from the height of the calculated value of the formula [hs + x × n] to the height of the calculated value of the formula [h2 + xx × n].

  When the height [Hc] of the trailing edge of the sheet detected in the first sheet is higher than the predetermined height [h2] (step S19: NO), the control unit 101 determines whether the sheet stacking surface and the pressing surface 5b are The control motor 7 of the end stopper 5a is driven so that the height (opening amount) between the end stoppers 5a becomes the calculated value of the equation [h3 + x × n] (step S21). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a is raised from the height of the calculated value of the formula [hs + x × n] to the height of the calculated value of the formula [h3 + xx × n].

  In this way, in the sheet processing apparatus 100, the opening amount is varied according to the number of sheets while maintaining the opening amount of the end stopper 5a determined by the height [Hc] of the trailing edge of the first sheet.

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the curl generated at the trailing edge of the succeeding sheet s2 is reliably inserted between the sheet stacking surface and the pressing surface 5b.

  Returning to the description of FIG. Thereafter, the control unit 101 rotates the leading end roller 2a of the sheet shifting arm 2 by a predetermined amount counterclockwise (step S22) and stops, and then executes the process of step S15.

  As a result, the sheet processing apparatus 100 performs an operation as shown in FIG. Specifically, the pressing surface 5b is lowered to the height calculated by the equation [hs + x × n], and the curl generated at the rear end of the conveyed sheet s2 is sandwiched.

  Returning to the description of FIG. When the sheet s to be aligned at the rear end is not a bundle of final sheets (step S16: NO), the control unit 101 returns to the process of step S3 and repeats the above-described process in order to convey the subsequent sheet.

  On the other hand, when the sheet s to be aligned at the rear end is a bundle of final sheets (step S16: YES), the control unit 101 controls the driving unit 103 to perform stapling processing (sheet processing) as follows. .

  The control unit 101 drives the control motor 7 so that the pressing surface 5b of the end stopper 5a keeps pressing the sheet bundle in which the trailing ends of the sheets are aligned, and with respect to a stapler (not shown). Instructing binding (stapling) to a sheet bundle (step S100).

  Thereafter, the control unit 101 turns on the drive solenoid (not shown) of the sheet shifting arm 2 (step S101), raises the sheet shifting arm 2, and turns off the opening solenoid (not shown) of the paper discharge driven roller 3b ( Step S102), the paper discharge driven roller 3b is lowered.

  Subsequently, the control unit 101 drives the control motor 7 of the end stopper 5a (step S103), raises the end stopper 5a to the original position (uppermost position), and drives a paper discharge motor (not shown). In step S104, the sheet bundle (sheet bundle after stapling) sandwiched between the sheet discharge roller 3a and the sheet discharge driven roller 3b is conveyed to the sheet discharge tray 9.

  Further, the control unit 101 determines whether or not the discharged sheet bundle is the final bundle requested from the image forming apparatus 200 (step S105).

  When the discharged sheet bundle is the requested final bundle (step S105: YES), the control unit 101 turns off the drive solenoid (not shown) of the sheet shifting arm 2 (step S106), and the sheet shifting arm 2 Is lowered, and a paper discharge motor (not shown) is stopped (step S107).

  On the other hand, when the discharged sheet bundle is not the requested final bundle (step S105: NO), the control unit 101 returns to the process of step S2 and repeats the above-described process.

  In this way, the sheet processing apparatus 100 performs an operation as shown in FIG. 15, and the requested sheet bundle sn after the sheet processing is discharged.

  Returning to the description of FIG. When the detected height [Hc] of the trailing edge of the sheet is higher than the predetermined height [h3] (step S304: NO), the control unit 101 determines that the height of the trailing edge of the sheet exceeds the product standard. (Abnormal) is determined, the drive unit 103 is controlled as follows, and an end process is performed.

  As illustrated in FIG. 9, the control unit 101 transmits notification information indicating that an abnormality has occurred to the control unit 201 included in the image forming apparatus 200 (step S200).

  Thereafter, the control unit 101 turns on the drive solenoid (not shown) of the sheet shifting arm 2 (step S201), raises the sheet shifting arm 2, and turns off the opening solenoid (not shown) of the paper discharge driven roller 3b ( Step S202), the paper discharge driven roller 3b is lowered.

  Subsequently, the control unit 101 drives the control motor 7 of the end stopper 5a (step S203), raises the end stopper 5a to the original position (uppermost position), and drives a paper discharge motor (not shown). In step S204, the sheet bundle sn sandwiched between the sheet discharge roller 3a and the sheet discharge driven roller 3b is conveyed to the sheet discharge tray 9.

  Subsequently, the control unit 101 turns off the drive solenoid (not shown) of the sheet shifting arm 2 (step S205), lowers the sheet shifting arm 2, and stops the paper discharge motor (not shown) (step S206).

<Summary>
As described above, according to the sheet processing apparatus 100 according to the present embodiment, the detection unit 102 (rear end height detection unit) detects the curl amount (height) of the rear end of the sheet. In the sheet processing apparatus 100, the control unit 101 determines the curl direction generated at the trailing edge of the sheet based on the detection information. In the sheet processing apparatus 100, based on the detection information and the determination information, the sheet processing apparatus 100 has a surface (sheet end contact surface) on which a sheet end stacked on the processing tray 4 abuts and a pressing surface 5b that presses the sheet end. Is moved vertically (moved up and down) with respect to the sheet stacking surface of the processing tray 4, and the sheet stacking surface and the pressing surface 5b of the end stopper 5a are moved. The height (opening amount) is variably controlled.

  As a result, the sheet processing apparatus 100 can align the trailing edges of the sheets with high accuracy.

[Second Embodiment]
In the first embodiment, the configuration in which the sheet processing apparatus is provided in the electrophotographic process type image forming apparatus, receives a printed sheet, and performs a predetermined sheet processing has been described.

  In the electrophotographic process method, after each process of exposure (latent image), development, and transfer, fixing processing by heating and pressurization is performed to fix the toner image on the sheet (transfer paper). Therefore, in the electrophotographic process method, a difference occurs in the moisture content between the front and back of the sheet, and the height and direction of the curl generated at the trailing edge of the sheet is determined by the heating amount at the time of fixing and the sheet discharge method. In the electrophotographic process method, since the toner fixing process does not greatly affect the formed image, if the height of the curl generated on the first sheet is detected and the direction of the curl is determined, the second and subsequent sheets are used. The same processing can be performed.

  However, in the case of an ink jet image forming apparatus, ink containing a large amount of moisture is directly dropped onto a sheet, so that the curl height and direction differ depending on the printing amount. Therefore, in the inkjet method, if the same process as the electrophotographic process method (the second and subsequent sheets are processed based on the detection information and determination information of the first sheet), a large error occurs in the alignment accuracy of the sheet trailing edge. Can be considered.

  Therefore, in the present embodiment, a sheet process corresponding to an image processing apparatus in which the height and direction of curl changes for each printed sheet (printing paper), such as an inkjet method, is proposed. In the following description, only items different from the first embodiment will be described, and the same items will be denoted by the same reference numerals, and the description thereof will be omitted.

<Seat trailing edge alignment function>
The sheet trailing edge alignment function according to the present embodiment is realized by executing the following processing by the control unit 101 (for example, “CPU”) mounted on the sheet processing apparatus 100. The functional configuration for realizing the sheet trailing edge alignment function is the same as the configuration example shown in FIG.

FIG. 16 is a flowchart illustrating an example of a sheet processing procedure including a sheet trailing edge alignment process according to the present embodiment.
The difference between FIG. 9 and FIG. 16 is the processing procedure of steps S39 to S45. Therefore, the processing procedures of steps S30 to S38 and steps S500 to S507 shown in FIG. 16 are omitted from the processing procedures of steps S1 to S8 and steps S100 to S107 shown in FIG.

  In the sheet processing apparatus 100, since the processing target is the sheet bundle sn, the height of the trailing edge of the sheet detected by the trailing edge height detection sensor 11 serving as the detection unit 102 is not zero. For this reason, after processing step S38, the control unit 101 acquires the height of the trailing edge of the sheet at this time, that is, the output value [hx] of the trailing edge height detection sensor 11 (step S39).

  Subsequently, the control unit 101 performs the curl direction determination process shown in FIG. 10 (step S40). When the control unit 101 determines that the curl is downward curl (back curl) from the determination result (the bit value of the determination flag) (step S40: YES), the height (opening amount) between the sheet stacking surface and the pressing surface 5b is determined. ) Is driven to drive the control motor 7 of the end stopper 5a (step S41). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a moves to the position of the height [hx]. That is, in the sheet processing apparatus 100, in the case of downward curl (back curl), the pressing surface 5 of the end stopper 5 a is driven and controlled so as to be the detection height of the rear end height detection sensor 11.

  Thereafter, the control unit 101 rotates the leading roller 2a of the sheet shifting arm 2 counterclockwise by a predetermined amount (step S42), and the height (opening amount) between the sheet stacking surface and the pressing surface 5b is expressed by the formula The control motor 7 of the end stopper 5a is driven so that the calculated value of [hs + hx] is obtained (step S43). [Hs] is a value in a range of 0 ≦ [hs] ≦ [Δh], and indicates a height at which the sheet bundle sn stacked on the processing tray 4 is not damaged and can be held. Value.

  If the sheet s to be aligned at the trailing edge is not a bundle of final sheets (step S44: NO), the control unit 101 returns to the process of step S31 and performs the processes from step S31 to S43 in order to convey the subsequent sheet. repeat.

  On the other hand, when the sheet s to be aligned at the rear end is a bundle of final sheets (step S44: YES), the control unit 101 performs stapling (sheet processing) shown in steps S500 to S507.

  If the control unit 101 determines that the curl is upward curl (face curl) from the determination result (the bit value of the determination flag) (step S40: NO), the height (between the sheet stacking surface and the pressing surface 5b ( The control motor 7 of the end stopper 5a is driven so that the (opening amount) becomes [hx + Δh] (step S45). Thereby, in the sheet processing apparatus 100, the pressing surface 5b of the end stopper 5a moves upward from the height [hx] to the position [hx + Δh]. That is, in the sheet processing apparatus 100, in the case of upward curl (face curl), drive control is performed so that the pressing surface 5 of the end stopper 5 a is raised by a predetermined amount from the detection height of the rear end height detection sensor 11. To do.

<Summary>
As described above, according to the sheet processing apparatus 100 according to the present embodiment, the detection unit 102 (rear end height detection unit) detects the curl amount (height) of the rear end of the sheet. In the sheet processing apparatus 100, the control unit 101 determines the curl direction generated at the trailing edge of the sheet based on the detection information. The sheet processing apparatus 100 is a surface (sheet end contact surface) on which a sheet end stacked on the processing tray 4 comes into contact based on detection information and determination information obtained for each sheet by the control unit 101. And an end stopper 5a (end aligning means) having a pressing surface 5b for pressing the sheet end are moved vertically (moved up and down) with respect to the sheet stacking surface of the processing tray 4, and the sheet stacking surface and the end The height (opening amount) between the pressing portion 5b of the portion stopper 5a is variably controlled. That is, the sheet processing apparatus 100 detects the height of the trailing edge of the sheet and determines the curl direction generated at the trailing edge of the sheet one by one, and variably controls the opening amount based on the obtained detection information and determination information.

  As a result, the sheet processing apparatus 100 can align the trailing edge of the sheet with high accuracy without depending on the type of image forming method.

  Finally, the present invention is not limited to the requirements shown here, such as combinations of other elements with the shapes and configurations described in the above embodiments. With respect to these points, the present invention can be changed within a range that does not detract from the gist of the present invention, and can be appropriately determined according to the application form.

1 Conveying roller pair 2 Sheet shifting arm (a: tip roller, b: support shaft)
3 a: paper discharge roller, b: paper discharge driven roller 4 processing tray 5 a: end stopper, b: pressing surface 6 pressing member 7 control motor (a: gear)
8 Entrance sensor 9 Paper discharge tray 10 Side alignment member 11 Rear end height detection sensor (a: sensor, b: disk, c: shaft, d: pendulum, e: stopper)
12 shafts (a: gear)
100 Sheet Processing Device 101 Control Unit (CPU: Central Processing Unit)
102 Detection Unit 103 Drive Unit 200 Image Forming Apparatus 201 Control Unit (Controller: Control Board with CPU)
s sheet sn sheet bundle

JP 2005-22833 A

Claims (10)

A sheet processing apparatus that performs predetermined output processing on a conveyed sheet,
A processing tray for stacking conveyed sheets;
Edge aligning means comprising a surface against which a sheet end stacked on the processing tray abuts and a surface pressing the sheet end;
A trailing edge height detecting means for detecting the height of the trailing edge of the sheet;
Driving means for driving the end alignment means;
Control means for controlling the driving means based on detection information by the trailing edge height detection means and determination information on the curl direction generated at the trailing edge of the sheet determined from the detection information,
The control means includes
Controlling the driving means according to the detected height of the trailing edge of the sheet and the determined curling direction, moving the edge aligning means perpendicularly to the sheet stacking surface of the processing tray, and A sheet processing apparatus that variably controls a height between the sheet and a surface that presses the sheet edge. The control means includes
A plurality of control values for controlling the height between the sheet stacking surface and the surface that presses the sheet edge, which is assumed from the detected height of the sheet trailing edge and the amount of curl generated at the sheet trailing edge. The sheet processing apparatus according to claim 1, wherein the driving unit is controlled based on the sheet processing unit. The control means includes
The height between the sheet stacking surface and the surface pressing the sheet edge is
The control value determined based on the detected height of the trailing edge of the sheet and the determined curl direction, the thickness of the sheet to be processed, and the height calculated from the number of sheets as the processing unit, The sheet processing apparatus according to claim 1 or 2, wherein the driving unit is controlled. The surface that holds the end of the sheet provided in the end aligning means,
Subsequent sheets are conveyed, and when the end alignment means is moved under the control of the control means,
4. The sheet processing apparatus according to claim 1, further comprising a pressing member that presses an end of a preceding sheet stacked on the processing tray. 5. The control means includes
Performing differential operation on the output pulse indicating the height of the trailing edge of the sheet detected while the trailing edge of the sheet passes through the trailing edge height detection means from the start of detection,
Based on the calculation result and a preset threshold,
5. The sheet processing apparatus according to claim 1, wherein the curl direction generated at the rear end of the sheet is determined to be upward or downward. The rear end height detecting means is
For each conveyed sheet, the height of the trailing edge of the sheet is detected,
The control means includes
For each conveyed sheet, determine the curl direction generated at the trailing edge of the sheet,
6. The sheet processing apparatus according to claim 1, wherein the driving unit is controlled based on the detection information and the determination information. The end alignment means comprises:
The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is provided at a plurality of locations. The driving means includes
The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a stepping motor.   An image forming apparatus comprising the sheet processing apparatus according to claim 1. A sheet processing method in a sheet processing apparatus for performing predetermined output processing on a conveyed sheet,
A trailing edge height detection procedure for detecting the trailing edge height of the conveyed sheet;
The edge aligning portion having a surface with which the sheet end loaded on the processing tray abuts and a surface for pressing the sheet end is arranged so that the sheet trailing edge height detected by the trailing edge height detection procedure and the sheet trailing edge are detected. Control procedure for variably controlling the height between the sheet stacking surface and the surface that presses the end of the sheet by moving the sheet tray perpendicularly to the sheet stacking surface of the processing tray according to the curl direction generated at the end And a sheet processing method.