Post-processing device and image formation device

Abstract

To enable a sheet to be loaded onto a discharge tray smoothly even if a lower curl occurs in a sheet bundle loaded into the discharge tray.SOLUTION: A controller causes a rear end pressing member 7 to press a rear end of a pring sheet on a discharge tray 5 when print setting for the print sheet does not meet lower curl conditions. Further, the controller determines whether to cause the rear end pressing member 7 to press the rear end of the print sheet on the discharge tray 5 according to a type of post processing when the print setting meets the lower curl conditions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a post-processing device and an image forming apparatus.

Background Art

[0002] A certain image forming apparatus includes a member that holds the rear end of a stack of sheets loaded on a discharge tray (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a downward curl (a curl in which the inner side of the sheet curvature faces downward) occurs in the stack of sheets loaded on the discharge tray, if the rear end of the stack of sheets is held as described above, the curvature of the downward curl becomes stronger, and the difference between the highest position of the stack of sheets and the position of the discharge port in the height direction becomes smaller. When subsequent sheets are discharged onto the discharge tray, problems (such as rounding of the leading edge of the subsequent sheet due to contact of the subsequent sheet with the top sheet of the stack of sheets, and protrusion of the top sheet) may occur.

[0005] The present invention has been made in view of the above problems, and an object thereof is to obtain a post-processing device and an image forming apparatus that can satisfactorily stack sheets on a discharge tray even when a downward curl occurs in the stack of sheets loaded on the discharge tray.

Means for Solving the Problems

[0006] The post-processing apparatus according to the present invention includes a processing tray on which a printed sheet is placed for post-processing, an intermediate roller that conveys the printed sheet to the processing tray, a discharge tray on which the printed sheet after the post-processing is placed, a discharge roller that discharges the printed sheet to the discharge tray, a rear-end pressing member, and a controller that causes the rear-end pressing member to press the rear end of the printed sheet on the discharge tray when the print setting for the printed sheet does not satisfy the downward curl condition. Then, when the print setting satisfies the downward curl condition, the controller determines whether to cause the rear-end pressing member to press the rear end of the printed sheet on the discharge tray according to the post-processing type of the post-processing.

[0007] The image processing apparatus according to the present invention includes the above-described post-processing apparatus, and supplies a printed sheet after printing is performed by an inkjet method to the post-processing apparatus.

Effects of the Invention

[0008] According to the present invention, a post-processing apparatus and an image forming apparatus capable of satisfactorily stacking sheets on a discharge tray even if downward curl occurs in a stack of sheets stacked on the discharge tray can be obtained.

[0009] The above or other objects, features, and advantages of the present invention will become more apparent from the following detailed description together with the accompanying drawings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a side view showing the mechanical configuration of a post-processing apparatus according to an embodiment of the present invention. The post-processing apparatus shown in FIG. 1 may be a single apparatus or may be incorporated in an image forming apparatus such as a multifunction machine, and is supplied with a print sheet after printing by a print engine, and a predetermined post-processing (stapling process, sorting process, etc. for a plurality of print sheets) is executed on the print sheet.

[0013] The post-processing apparatus shown in FIG. 1 includes an intermediate roller 1, a stopper guide 2, a processing tray 3, a discharge roller 4, a discharge tray 5, a discharge guide 6, and a trailing edge pressing member 7.

[0014] The intermediate roller 1 conveys the print sheet to be post-processed to above the processing tray 3. The intermediate roller 1 is driven by a motor (not shown).

[0015] The stopper guide 2 is disposed at one end side of the processing tray 3, and the end of the print sheet on the processing tray 3 abuts thereon.

[0016] The processing tray 3 is a substantially plate-shaped member that is inclined, and the print sheet to be post-processed is placed thereon. Post-processing (such as stapling and sorting) is performed on one or more print sheets placed on the processing tray 3.

[0017] In this embodiment, after the rear end portion of the printed sheet passes through the intermediate roller 1, it is guided to the processing tray 3 while receiving contact from a sheet contact member (not shown), and is brought into contact with the stopper guide 2 by a drawing paddle (not shown) to be aligned.

[0018] The discharge roller 4 is movable by the discharge guide 6, and is separated from each other until the post-processing is completed so that the printed sheet placed on the processing tray 3 and the printed sheet newly conveyed to the processing tray 3 can move through the gap of the discharge roller 4. After the completion of the post-processing, the printed sheet is nipped and conveyed (discharged) onto the discharge tray 5. Note that when no post-processing is performed, the discharge roller 4 nips the printed sheet conveyed by the intermediate roller 1 and conveys (discharges) it onto the discharge tray 5.

[0019] The discharge tray 5 is a member on which the printed sheet after post-processing is placed, and is capable of moving up and down.

[0020] The rear end pressing member 7 is a member for pressing the rear end of the printed sheet (sheet bundle) stacked on the discharge tray 5, and is fixed to the rotation shaft 7a so as to be rotatable between a first position (retracted position) and a second position (sheet pressing position).

[0021] FIG. 2 is a block diagram showing the electrical configuration of the post-processing apparatus according to the embodiment of the present invention. As shown in FIG. 2, the post-processing apparatus according to the embodiment further includes a motor 21 that drives the intermediate roller 1, the discharge roller 4, etc., a rotation mechanism 22 such as a motor that rotates the rear end pressing member 7, and a controller 23 that controls the motor 21 and the rotation mechanism 22.

[0022] The controller 23 includes an ASIC (Application Specific Integrated Circuit) or a computer, and uses the ASIC or the computer to control the motor 21, the rotation mechanism 22, a staple mechanism (not shown), a sorting mechanism (not shown) that moves the processing tray 3 in the sheet width direction (perpendicular to the conveyance direction), etc., to perform post-processing of a type specified by the user. Further, the controller 23 adjusts the height of the discharge tray 5 according to the thickness of the entire printed sheet (i.e., the stack of sheets) placed on the discharge tray 5, and controls the rotation mechanism 22 to perform pressing of the rear end of the stack of sheets on the discharge tray 5 by the rear end pressing member 7 as necessary.

[0023] FIG. 3 is a diagram for explaining the position of the rear end pressing member 7 when the print setting for the printed sheet does not satisfy the undercurl condition. FIG. 4 is a diagram for explaining the position of the rear end pressing member 7 when the rear end pressing is not performed when the print setting for the printed sheet satisfies the undercurl condition.

[0024] For example, as shown in FIG. 3, when the print setting for the printed sheet 101 does not satisfy the undercurl condition, the controller 23 causes the rear end pressing member 7 to press the rear end of the printed sheet 101 on the discharge tray 5. Note that the print setting is obtained, for example, from an inkjet printing engine for the printed sheet 101 or a preceding inkjet image forming apparatus.

[0025] Here, the above-mentioned undercurl condition is set for the printing rate of printing on the printed sheet 101 and the characteristics of the printed sheet 101 (size, sheet type, basis weight, paper texture, color, moisture content, etc.).

[0026] On the other hand, for example, as shown in FIG. 4, when the print setting for the printed sheet 101 satisfies the undercurl condition, the controller 23 determines whether to cause the rear end pressing member 7 to press the rear end of the printed sheet 101 on the discharge tray 5 according to the type of post-processing of the specified post-processing.

[0027] Specifically, in this case, when the post - processing type is staple, the controller 23 determines not to press the rear end of the printed sheet 101 on the discharge tray 5 against the rear - end pressing member 7. Also, in this case, when the post - processing type is sorting, for example, as shown in FIG. 4, the controller 23 determines to press the rear end of the printed sheet 101 on the discharge tray 5 against the rear - end pressing member 7.

[0028] In addition, when the printed sheet is to be discharged to the discharge tray 5 without post - processing when the above - mentioned print setting satisfies the downward curl condition, the controller 23 determines to press the rear end of the printed sheet 101 on the discharge tray 5 against the rear - end pressing member 7.

[0029] Also, even when the controller 23 determines to press the rear end of the printed sheet 101 on the discharge tray 5 against the rear - end pressing member 7, when the downward curl amount based on the print setting is equal to or greater than a predetermined threshold value, the controller 23 does not press the rear end of the printed sheet 101 on the discharge tray 5 against the rear - end pressing member 7. For example, the downward curl amount is derived from the printing rate of the printed sheet 101, the number of printed sheets 101 on the discharge tray 5, etc. Specifically, for example, for each printed sheet 101, an individual curl amount of one printed sheet 101 is derived based on the printing rate, and the sum of the individual curl amounts of the printed sheets 101 on the discharge tray 5 is derived as the above - mentioned downward curl amount. Note that the individual curl amount corresponding to the printing rate is preset and can be changed by the user.

[0030] Next, the operation of the above post - processing apparatus will be described.

[0031] When receiving a request for a post - processing job, the controller 23 first raises the discharge guide 6, opens the discharge port 4a, specifies the width of the printed sheet 101 based on the request, and arranges a width - aligning cursor (not shown) at a position corresponding to the width of the printed sheet 101.

[0032] Further, the controller 23 adjusts the height position of the discharge tray 5 according to the presence or absence of the printed sheet 101 on the discharge tray 5 and the like.

[0033] Then, the intermediate roller 1 conveys the printed sheet printed by the inkjet method from the preceding device (such as a print engine or a separate image forming device).

[0034] When post-processing is executed, after the trailing edge of the printed sheet passes through the intermediate roller 1, the printed sheet 101 is placed on the processing tray 3 by the sheet contact member or the retracting paddle. A plurality of printed sheets are sequentially placed on the processing tray 3. At this time, the post-processing designated by the user is executed on the plurality of printed sheets, and then, the printed sheet after the post-processing is discharged to the discharge tray 5 by the discharge roller 4.

[0035] When post-processing is not executed, the printed sheet conveyed by the intermediate roller 1 is discharged to the discharge tray 5 by the discharge roller 4.

[0036] In this way, the printed sheets 101 are stacked on the discharge tray 5. At this time, the controller 23 determines whether to perform the trailing edge pressing of the printed sheet 101 on the discharge tray 5 by the trailing edge pressing member 7, and according to the determination result, retracts the trailing edge pressing member 7 and does not perform the trailing edge pressing, or rotates the trailing edge pressing member 7 to perform the trailing edge pressing.

[0037] FIG. 5 is a flowchart for explaining the control of the trailing edge pressing member 7 in the post-processing device shown in FIGS. 1 and 2.

[0038] First, the controller 23 determines whether the print setting satisfies the downward curl condition (step S1).

[0039] When it is determined that the print settings satisfy the downward curl condition, the controller 23 determines whether the post-processing type is stapling (step S2). If the post-processing type is stapling, the controller 23 does not execute the trailing edge hold (step S3).

[0040] If the post-processing type is not stapling (such as when the post-processing type is sorting), the controller 23 derives the amount of downward curl and determines whether the amount of downward curl is equal to or greater than a predetermined threshold (step S4). If the amount of downward curl is equal to or greater than the predetermined threshold, the controller 23 does not execute the trailing edge hold (step S3). On the other hand, if the amount of downward curl is less than the threshold, the controller 23 executes the trailing edge hold (step S5).

[0041] Note that if it is determined in step S2 that the print settings do not satisfy the downward curl condition, the controller 23 executes the trailing edge hold (step S5).

[0042] As described above, according to the above embodiment, when the print settings for the print sheet 101 do not satisfy the downward curl condition, the controller 23 causes the trailing edge hold member 7 to hold the trailing edge of the print sheet 101 on the discharge tray 5. Further, when the print settings satisfy the downward curl condition, the controller 23 determines whether to cause the trailing edge hold member 7 to hold the trailing edge of the print sheet 101 on the discharge tray 5 according to the post-processing type.

[0043] Thereby, even if downward curl occurs in the sheet stack loaded on the discharge tray, the sheets can be satisfactorily loaded on the discharge tray 5. Here, when the print sheet 101 is discharged to the discharge tray 5 one by one, such as in the case of sorting or without post-processing, the trailing edge hold is appropriately performed, and when the downward curl is suppressed by post-processing such as stapling, the trailing edge hold is not performed.

[0044] It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing the intended advantages. That is, it is intended that such changes and modifications be included within the scope of the claims.

Industrial Applicability

[0045] The present invention is applicable to, for example, a post-processing device of an image forming apparatus.

Explanation of Signs

[0046] 1 Intermediate roller 2 Stopper guide 3 Processing tray 4 Discharge roller 5 Discharge tray 7 Rear end pressing member 23 Controller

Claims

1. A processing tray on which a printed sheet is placed for post-processing, An intermediate roller that conveys the printed sheet to the processing tray, A discharge tray on which the printed sheet after the post-processing is placed, A discharge roller that discharges the printed sheet to the discharge tray, A rear-end pressing member, When the print setting for the printed sheet does not satisfy the downward curl condition, a controller that causes the rear-end pressing member to press the rear end of the printed sheet on the discharge tray, When the print setting satisfies the downward curl condition, the controller determines whether to cause the rear-end pressing member to press the rear end of the printed sheet on the discharge tray according to the post-processing type of the post-processing, A post-processing apparatus characterized by the above.

2. When the print setting satisfies the downward curl condition and the printed sheet is discharged to the discharge tray without performing the post-processing, the controller determines to cause the rear-end pressing member to press the rear end of the printed sheet on the discharge tray. The post-processing apparatus according to Claim 1, characterized by this.

3. Even when the controller determines to cause the rear-end pressing member to press the rear end of the printed sheet on the discharge tray, when the downward curl amount based on the print setting is equal to or greater than a predetermined threshold, the controller does not cause the rear-end pressing member to press the rear end of the printed sheet on the discharge tray. The post-processing apparatus according to Claim 1, characterized by this.

4. The downward curl condition is set for the printing rate of the print on the printed sheet and the characteristics of the printed sheet. The post-processing apparatus according to Claim 1, characterized by this.

5. When the print setting satisfies the undercurl condition, the controller determines that when the post-processing type is staple, the rear end pressing member is not allowed to press the rear end of the printed sheet on the discharge tray, and when the post-processing type is sorting, the controller determines that the rear end pressing member is allowed to press the rear end of the printed sheet on the discharge tray. The post-processing device according to claim 1, characterized by the above.

6. The image forming apparatus includes the post-processing device according to any one of claims 1 to 5, supplying the printed sheet after printing is performed by an inkjet method to the post-processing device, and is characterized by the above.

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