POST-PROCESSING APPARATUS

Abstract

When performing post-processing on a preceding sheet of a recording medium stacked on a processing tray, a control portion arranges a first discharge roller and a second discharge roller in an apart position, and when the leading end of a subsequent sheet of the recording medium conveyed along a conveyance passage passes between the first and second discharge rollers and the trailing end reaches a branch point between the conveyance passage and the retraction passage, the control portion rotates a pair of intermediate conveyance rollers to retract the subsequent recording medium into a retraction passage.

Claims

1. A post-processing apparatus, comprising: a processing tray; a post-processing portion that performs post-processing on a recording medium stacked on the processing tray; a conveyance passage that extends toward the processing tray; a pair of intermediate conveyance rollers that conveys the recording medium along the conveyance passage toward the processing tray; a retraction passage provided at a position different from the conveyance passage, the retraction passage extending toward the pair of intermediate conveyance rollers; a pair of discharge rollers that discharges the recording medium on the processing tray to a discharge port; a control portion that controls operation of the post-processing portion, the pair of intermediate conveyance rollers, and the pair of discharge rollers; wherein the pair of discharge rollers is composed of a first discharge roller and a second discharge roller, the first and second discharge rollers is movable between a nip forming position, in which they form a nip portion by making contact with each other, and an apart position, in which they are apart from each other, and when performing post-processing on a preceding sheet of the recording medium stacked on the processing tray, the control portion arranges the first and second discharge rollers in the apart position, and when the leading end of a subsequent sheet of the recording medium conveyed along the conveyance passage passes between the first and second discharge rollers and the trailing end reaches a branch point between the conveyance passage and the retraction passage, the control portion rotates the pair of intermediate conveyance rollers to retract the subsequent sheet of the recording medium into the retraction passage.

2. The post-processing apparatus according to claim 1, wherein an amount of opening between the first and second discharge rollers arranged in the apart position is larger than a thickness of a maximum number of sheets of the recording medium that the post-processing portion can perform post-processing on.

3. The post-processing apparatus according to claim 1, wherein if the first and second discharge rollers move away from each other by more than a prescribed distance, the control portion stops performing the post-processing in the post-processing portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a schematic diagram showing a configuration of a post-processing apparatus according to an embodiment of the present disclosure.

[0010] FIG. 2 is a schematic diagram showing the internal construction of a top part of the post-processing apparatus according to the embodiment of the present disclosure.

[0011] FIG. 3 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0012] FIG. 4 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0013] FIG. 5 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0014] FIG. 6 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0015] FIG. 7 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0016] FIG. 8 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

[0017] FIG. 9 is an illustrative diagram showing the progress of the conveyance of a sheet S according to the embodiment of the present disclosure.

DETAILED DESCRIPTION

[0018] An embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a configuration of a post-processing apparatus 20 according to the embodiment of the present disclosure and the post-processing apparatus 20 is coupled to an image forming apparatus 100 to constitute part of an image forming system. While this embodiment takes up a multifunction peripheral as one example of the image forming apparatus 100, the post-processing apparatus 20 of the present disclosure can also be coupled to other than a digital multifunction peripheral, such as to a laser printer, an inkjet printer, or a facsimile device.

[0019] The image forming apparatus 100 is what is called an in-body sheet discharge type digital multifunction peripheral. In an upper part of a main body of the image forming apparatus 100, an image reading portion 8 that reads an image of a document as an electric signal is provided and, on it, a document conveyance device 3 is fitted. To the left side of the main body of the image forming apparatus 100, the post-processing apparatus (sheet post-processing apparatus) 20 is coupled.

[0020] In the main body of the image forming apparatus 100, there are provided an image forming portion for forming a toner image on paper (sheet), a fixing device for fixing the toner image to the paper, a paper discharge portion for conveying the paper after fixing and discharging it out of the main body of the image forming apparatus 100, a main body control portion 80, and the like. The main body control portion 80 controls the operation of the image forming apparatus 100 and is configured to be able to communicate with a post-processing control portion (control portion) 81 in the post-processing apparatus 20 to control the post-processing control portion 81.

[0021] FIG. 2 is a schematic diagram showing the internal construction of a top part of the post-processing apparatus 20. The post-processing apparatus 20 includes a housing 21, a stapling device (post-processing portion) 54, a punch hole forming device 60, a processing tray 51, a discharge tray 50, an upper tray 55, a conveyance passage 41, a branch passage 42, a retraction passage 43, a pair of intermediate conveyance rollers 412, a pair of discharge rollers 33, a pair of upper discharge rollers 421, a pair of upstream conveyance rollers 411, a retraction roller 431, and a post-processing control portion (control portion) 81.

[0022] The housing 21 is in the shape of a rectangular parallelepiped and in a top part of the right side plate, an inlet 22 is open. In the top plate of the housing 21, an upper discharge port 44 is open and in a top part of the left side plate, a discharge port 32 is open. The sheet S printed in the image forming apparatus 100 is conveyed through the inlet 22 into the housing 21.

[0023] The conveyance passage 41 extends toward the processing tray 51. More specifically, in the housing 21, the conveyance passage 41 extends from the inlet 22 to the discharge port 32 and the sheet S is conveyed along the conveyance passage 41.

[0024] The pair of intermediate conveyance rollers 412 and the pair of upstream conveyance rollers 411 are arranged along the conveyance passage 41. The pair of intermediate conveyance rollers 412 is arranged downstream of the pair of upstream conveyance rollers 411 in the sheet conveyance direction. The pair of intermediate conveyance rollers 412 conveys the sheet S along the conveyance passage 41 toward the processing tray 51.

[0025] More specifically, the pair of intermediate conveyance rollers 412 is composed of a lower conveyance roller 412a and an upper conveyance roller 412b (see FIG. 3). The lower conveyance roller 412a is arranged below the upper conveyance roller 412b across the conveyance passage 41 and is driven by a motor (not shown). The upper conveyance roller 412b rotates by following the lower conveyance roller 412a.

[0026] The pair of upstream conveyance rollers 411 is arranged upstream of the branch passage 42 in the sheet conveyance direction. The pair of upstream conveyance rollers 411 conveys the sheet S to the pair of intermediate conveyance rollers 412 or to the branch passage 42.

[0027] The pair of discharge rollers 33 is arranged to the right of the discharge port 32 and discharges to the discharge port 32 a bundle of sheets S on the processing tray 51 that has been stapled. The pair of discharge rollers 33 can also reverse its rotation direction to return the sheet S passing through the pair of discharge rollers 33 toward the pair of intermediate conveyance rollers 412.

[0028] The pair of discharge rollers 33 is composed of a driving roller (first discharge roller) 331 that is driven by a motor (not shown) and a driven roller (second discharge roller) 332 that rotates by following the driving roller 331. The driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 can move between a nip forming position, in which they form a nip portion N by making contact with each other, and an apart position, in which they are apart from each other.

[0029] More specifically, the driving roller (first discharge roller) 331 is rotatably supported at one end of an arm 333. The other end of the arm 333 is rotatably supported on a rotation shaft 334. The arm 333 can pivot about the rotation shaft 334 as a fulcrum such that one end of the arm 333 swings up and down. Pivoting the arm 333 up results in the driving roller (first discharge roller) 331 moving away from the driven roller (second discharge roller) 332. Pivoting the arm 333 down results in the driving roller (first discharge roller) 331 coming into contact with the driven roller (second discharge roller) 332.

[0030] The amount of opening between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 in the apart position is previously stored in a storage portion (not shown) and is constant.

[0031] To the left of the discharge port 32, the discharge tray 50 is arranged. The discharge tray 50 is movable up and down to a position suitable for discharging the sheet S. In this embodiment, to the discharge tray 50, a stapled bundle of sheets S is discharged.

[0032] The branch passage 42 branches off the conveyance passage 41 upward and extends to the upper discharge port 44. The pair of upper discharge rollers 421 is arranged to the right of the upper discharge port 44 and discharges to the upper discharge port 44 the sheet S conveyed along the branch passage 42. To a side of the upper discharge port 44, the upper tray 55 is provided. Mainly discharged to the upper tray 55 is a sheet S that is not stapled.

[0033] The retraction passage 43 is provided at a position different from the conveyance passage 41 and extends toward the pair of intermediate conveyance rollers 412. The retraction roller 431 is arranged along the retraction passage 43 and is driven by a motor (not shown). The retraction roller 431 draws the sheet S from the conveyance passage 41 into the retraction passage 43. The retraction roller 431 conveys the sheet S retracted in the retraction passage 43 toward the pair of intermediate conveyance rollers 412.

[0034] The punch hole forming device 60 is arranged, in a top part of the post-processing apparatus 20, along the conveyance passage 41. The punch hole forming device 60 forms a punch hole in the sheet S conveyed along the conveyance passage 41.

[0035] The processing tray 51 is arranged below the conveyance passage 41 and tilts downward from the discharge port 32 rightward. In the processing tray 51 are stacked a plurality of sheets S to be stapled in the stapling device 54.

[0036] The processing tray 51 is provided with a pair of side fences 52 facing each other in the front-rear direction. The pair of side fences 52 is movable along the width direction of the sheet S (the direction crossing the discharge direction). Moving the pair of side fences 52 synchronously in the directions toward each other results in aligning the sheet S on the processing tray 51 in the width direction. Moving the pair of side fences 52 together in the width direction results in moving the bundle of sheets S in the width direction.

[0037] On a right end part of the processing tray 51, a sheet receiving plate 53 is provided. A right end part of a sheet bundle stacked on the processing tray 51 making contact with the sheet receiving plate 53 results in aligning the sheet S in the discharge direction.

[0038] The stapling device 54 (post-processing portion) performs a stapling process (post-processing) on a sheet (recording medium) P stacked on the processing tray 51. In this embodiment, the stapling device 54 is arranged below the conveyance passage 41, to the right of the processing tray 51.

[0039] The post-processing control portion (control portion) 81 controls the operation of the stapling device 54, the punch hole forming device 60, the pair of intermediate conveyance rollers 412, the pair of discharge rollers 33, the pair of upper discharge rollers 421, the pair of upstream conveyance rollers 411, and the retraction roller 431.

[0040] Next, the operation of conveying the sheet S in the post-processing apparatus 20 will be described. FIGS. 3 to 9 are illustrative diagrams showing the progress of the conveyance of the sheet S. As shown in FIG. 3, in an initial state, in which a first sheet S1 is conveyed, the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 are arranged at the nip forming position. The driving roller (first discharge roller) 331 and the lower conveyance roller 412a of the pair of intermediate conveyance rollers 412 rotate forward to convey the first sheet S1 along the conveyance passage 41 toward the conveyance direction X1.

[0041] As shown in FIG. 4, after the trailing end of the first sheet S1 leaves the pair of intermediate conveyance rollers 412, the driving roller (first discharge roller) 331 and the lower conveyance roller 412a of the pair of intermediate conveyance rollers 412 rotate backward to switch back the first sheet S1 in the switchback direction X2. The first sheet S1 having switched back is stacked on the processing tray 51.

[0042] As shown in FIG. 5, when a second sheet S2 is conveyed, the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 are arranged in the apart position. The second and subsequent sheets S2 are conveyed by the pair of intermediate conveyance rollers 412 to pass between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 toward the conveyance direction X1.

[0043] After the trailing end of the second sheet S2 leaves the pair of intermediate conveyance rollers 412, the trailing end of the second sheet S2 falls onto the processing tray 51. Thus, the second sheet S2 having switched back is stacked on top of the first sheet S1 on the processing tray 51.

[0044] As shown in FIG. 6, when a predetermined number of sheets S have been stacked on a processing tray 27 to form a sheet bundle (bundle of sheets S) SB, the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 are arranged in the apart position and the stapling device 54 performs the stapling process.

[0045] As shown in FIG. 7, the pair of discharge rollers 33 is in the apart position in a state where the sheet bundle SB is stacked on the processing tray 27. Thus, when the stapling process is performed, a subsequent sheet S3 can pass between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332.

[0046] As shown in FIG. 8, when the trailing end of the subsequent sheet S3 reaches a branch point P between the conveyance passage 41 and the retraction passage 43, the lower conveyance roller 412a rotates backward. Thus, the subsequent sheet S3 switched back in the switchback direction X2 and retracts in the retraction passage 43.

[0047] As shown in FIG. 9, in a state where the subsequent sheet S3 is retracted in the retraction passage 43, a further subsequent sheet S4 can be conveyed along the conveyance passage 41 toward the pair of intermediate conveyance rollers 412. Meanwhile, with the timing when the leading ends of the sheets S3 and S4 coincide with each other, the retraction roller 431 is rotated. Thus, with the leading ends of the sheets S3 and S4 coinciding with each other, the sheets S3 and S4 can be overlapped on each other. Rotating the pair of intermediate conveyance rollers 412 results in conveying the overlapping sheets S3 and S4 toward the pair of discharge rollers 33.

[0048] In this embodiment, when the post-processing control portion (control portion) 81 performs stapling (post-processing) on the preceding sheet bundle SB stacked on the processing tray 51, the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 are arranged in the apart position. Thus the subsequent sheet (recording medium) P3 conveyed along the conveyance passage 41 can pass between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332.

[0049] It is thus possible, when the trailing end of the subsequent sheet S3 reaches the branch point P between the conveyance passage 41 and the retraction passage 43, to rotate (rotate backward) the pair of intermediate conveyance rollers 412 to retract the subsequent sheet S3 into the retraction passage 43. This permits the leading ends of the further subsequent sheet S4 and the subsequent sheet S3 conveyed along the conveyance passage 41 to coincide with each other. It is thus possible to perform consecutively the operation of performing stapling (post-processing) on the sheet bundle SB and the operation of conveying the subsequent sheets S3 and S4 with their leading ends overlapping each other, and this helps enhance the efficiency of post-processing.

[0050] The amount of opening between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332 arranged in the apart position is preferably larger than the thickness of the maximum number of sheets (recording medium) S9 that the stapling device (post-processing portion) 54 can perform post-processing on.

[0051] Thus, even if the maximum number of sheets S that can be stapled (post-processed) are stacked on the processing tray 51, the subsequent sheet (recording medium) P3 can pass between the driving roller (first discharge roller) 331 and the driven roller (second discharge roller) 332. This helps further enhance the efficiency of post-processing.

[0052] If the driving roller (first discharge roller) 331 and driven roller (second discharge roller) 332 arranged in the apart position move away from each other by more than a prescribed distance, the post-processing control portion 81 is preferable to stop performing the stapling process (post-processing) in the post-processing portion.

[0053] Thus, even if during the stapling process (post-processing) the user accidentally lifts up the driving roller (first discharge roller) 331 and inserts fingers into the processing tray 51, the stapling process (post-processing) can be stopped for increased safety.

[0054] The embodiment of the present disclosure described above is not meant to limit the scope of the disclosure, which can thus be implemented with various modifications made without departing from the spirit of the present disclosure. For example, instead of the stapling device 54, a middle folding device (post-processing portion) that folds the sheet S in the middle may be provided.

[0055] The present disclosure is applicable to post-processing apparatuses including a stapling device that performs a stapling process.