JP2018177421A - Post-processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a post-processing device which prevents a sheet already arranged on a tray from being pushed out by a succeeding sheet.SOLUTION: A post-processing device 100 performs prescribed processing subsequently to image formation processing by an image formation apparatus. The post-processing device includes: a first discharge unit 210 which discharges sheets; a first tray 310 which temporarily holds the sheets; a second tray 320 which is located on the downstream side of the first tray in the discharge direction of the sheet; a tray drive unit which lowers the second tray from the first height position; an air blower unit 400 which forms an air stream between the second tray and the lower surface of the sheet; and a control unit which controls the air blower unit and the tray drive unit. The control unit includes: an air blower control part which causes the air blower unit to blow the air over a period in synchronization with a discharge operation period from the start to the end of sheet discharge by the first discharge unit; and a tray control part which causes the tray drive unit to lower the second tray from the first height position after the discharge operation period.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a post-processing apparatus that performs predetermined processing subsequent to image forming processing by an image forming apparatus.

  It is known to incorporate a blower into a discharge mechanism that discharges sheets (see Patent Documents 1 and 2). Patent Document 1 proposes that an air flow flowing in the sheet discharge direction be formed on the upper surface of the sheet to stabilize the sheet discharge. Patent Document 2 proposes feeding air between a plurality of sheets sequentially fed to reduce friction between the sheets.

JP, 2013-184809, A JP, 2013-136453, A

  With regard to a post-processing apparatus that performs a predetermined process following an image forming process by an image forming apparatus, a plurality of sheets are stacked on one tray to form a sheet bundle. When multiple sheets are being fed out sequentially, subsequent sheets may push the already stacked sheets on the tray in the discharge direction. If the above-mentioned prior art is applied to the post-treatment device, the air from the blower exerts an action to push the already stacked sheets on the tray in the discharge direction. Therefore, the above-mentioned prior art is not suitable for use in the discharge mechanism of the aftertreatment device.

  In addition, the frictional force generated between the sheets is influenced by the material of the sheet and the state of the image formed on the sheet. If the friction generated between the sheets is very large, the friction reducing effect using the air flow may be insufficient. Thus, the sheets on the tray may be pushed out by the subsequent sheets, even if the blower is arranged, so that the air does not hit the sheets already stacked on the tray.

  An object of the present invention is to provide a post-processing device having a mechanism for preventing sheets already arranged on a tray from being pushed out by a subsequent sheet.

  The post-processing apparatus according to one aspect of the present invention performs a predetermined process subsequent to the image forming process by the image forming apparatus. The post-processing apparatus includes: a first discharge unit that discharges a first sheet; a first tray that temporarily holds the first sheet discharged by the first discharge unit; and the first sheet in the discharge direction of the first sheet A second tray positioned downstream of the first tray, a tray drive unit for lowering the second tray from the first height position, the second tray, and the first discharged by the first discharge unit. And a control unit configured to control the blower unit and the tray driving unit. (I) an air flow control unit which blows air from the air blowing unit over a period synchronized with the discharge operation period from the start to the end of the discharge of the first sheet by the first discharge unit; ii) After the discharge operation period, the tray drive unit includes a tray control unit that lowers the second tray from the first height position.

  According to the above configuration, the air flow control unit of the control unit causes the air blowing unit to blow out the air during a period synchronized with the discharge operation period from the start to the end of the discharge of the first sheet by the first discharge unit. Thus, the air flow is formed between the second tray located downstream of the first tray in the discharge direction of the first sheet and the lower surface of the first sheet discharged by the first discharge portion. As a result, even if the first sheet has a sliding size on the second tray, the frictional force between the second tray and the first sheet is reduced. Therefore, the first sheet is smoothly held on the first tray without being impeded by the frictional force between the second tray and the first sheet.

  Since the blowout of air from the blower unit is synchronized with the discharge operation period, the air flow disappears after the discharge operation period. The frictional force between the second tray and the first sheet is increased, so that the first sheet is less likely to be pushed out by the subsequent sheets.

  The tray control unit of the control unit controls the tray drive unit and, after the discharge operation period, lowers the second tray from the first height position, so that the first sheet protruding toward the second tray from the first tray Area can be separated from the discharge path of the following sheet. Since the contact area between the first sheet and the subsequent sheet is small, the first sheet is less likely to be pushed out by the subsequent sheet.

  With regard to the above configuration, the control unit may include a detection unit that detects the first sheet discharged from the first discharge unit and generates a detection signal indicating the start and the end of the discharge. The air blowing control unit may control the air blowing unit according to the detection signal.

  According to the above configuration, the control unit includes the detection unit that detects the first sheet discharged from the first discharge unit and generates a detection signal representing the start and end of the discharge. The blowout period of air from the unit can be accurately synchronized with the discharge operation period.

  In the above configuration, the tray control unit may lower the second tray from the first height position if the first sheet is longer than the predetermined length in the discharge direction. If the first sheet is less than or equal to the predetermined length in the discharge direction, the second tray is maintained at the first height position.

  If the first sheet is long in the discharge direction, the contact area between the first sheet and the subsequent sheet tends to be large. According to the above configuration, if the first sheet is longer than the predetermined length in the discharge direction, the tray control unit lowers the second tray from the first height position, so that the first sheet and the subsequent sheets are included. The contact area between and decreases. Therefore, the first sheet is less likely to be pushed out by the subsequent sheets.

  If the first sheet is short in the discharge direction, the first sheet is less likely to contact the subsequent sheets. According to the above configuration, the second tray is maintained at the first height position if the first sheet is less than or equal to the predetermined length in the discharge direction, so unnecessary lowering of the second tray is Does not occur. That is, the post processor does not waste power unnecessarily.

  Regarding the above configuration, the tray control unit calculates the length of the first sheet in the discharge direction using the detection signal, and compares the calculated length with a predetermined threshold value. It is also good. The tray control unit may lower the second tray from the first height position if the calculated length exceeds the predetermined threshold. If the calculated length is less than or equal to the predetermined threshold value, the second tray may be maintained at the first height position.

  According to the above configuration, since the detection signal is used not only for notifying the discharge operation period but also for calculating the length of the first sheet, an additional signal for obtaining information indicating the length of the first sheet is used. The device is not required. Therefore, the post-processing device can have a simple structure.

  If the first sheet is long in the discharge direction, the contact area between the first sheet and the subsequent sheet tends to be large. According to the above configuration, if the calculated length exceeds the predetermined threshold, the tray control unit lowers the second tray from the first height position, so that the first sheet and the subsequent sheet are separated. The contact area between them becomes smaller. Therefore, the first sheet is less likely to be pushed out by the subsequent sheets.

  If the first sheet is short in the discharge direction, the first sheet is less likely to contact the subsequent sheets. According to the above configuration, if the calculated length is less than or equal to the predetermined threshold, the second tray is maintained at the first height position, so the second tray is not unnecessarily lowered. That is, the post processor does not waste power unnecessarily.

  Regarding the above configuration, the first discharge unit may sequentially discharge at least one sheet following the first sheet. An alignment unit that aligns the at least one sheet with the first sheet to form a sheet bundle so that the first tray has an edge of the at least one sheet overlapping an edge of the first sheet; May be included. The tray control unit lowers the second tray before the alignment unit completes the adjustment operation of adjusting the position of the first sheet on the first tray in the direction orthogonal to the discharge direction. May be

  According to the above configuration, the first discharge unit sequentially discharges at least one sheet following the first sheet, but since the tray control unit lowers the second tray, an excessively large frictional force is It does not occur between the first sheet and the at least one sheet. Thus, the first sheet is less likely to be pushed out by at least one subsequent sheet.

  The alignment portion of the first tray aligns the at least one sheet with the first sheet such that the edge of the at least one sheet overlaps the edge of the first sheet so that a high quality sheet bundle is formed on the first tray It will be done. Since the tray control unit lowers the second tray before the aligning unit completes the adjustment operation of adjusting the position of the first sheet in the direction orthogonal to the discharge direction on the first tray, the tray control unit lowers the second tray. A treatment period for lowering is not required separately. Thus, the aftertreatment device can have a high processing speed.

  With regard to the above configuration, the post-processing apparatus may further include a pulling mechanism that moves the at least one sheet in a pulling direction opposite to the discharging direction and places the at least one sheet on the first tray. The control unit controls the pull-in mechanism to move the at least one sheet in the pull-in direction, an alignment control unit that controls the alignment operation of the alignment unit, and the alignment of the alignment unit And a matching control unit that controls the operation. When the at least one sheet is moved in the pull-in direction under control of the pull-in control unit and disposed on the first tray, the alignment control unit executes the alignment operation in the alignment unit. You may

  According to the above configuration, the retraction mechanism moves the at least one sheet in the retraction direction opposite to the discharge direction under the control of the retraction control unit, and places the at least one sheet on the first tray. Are stacked on the first sheet. When at least one sheet is moved in the pull-in direction under control of the pull-in control unit and placed on the first tray, the alignment control unit causes the alignment unit to execute the alignment operation, so that the sheet bundle is It is formed on the first tray.

  Regarding the above configuration, the post-processing apparatus may further include a second discharge unit that discharges the sheet bundle from the first tray to the second tray. The second discharge unit may include a first roller, and a second roller moving between a close position close to the first roller and a separated position away from the first roller. The control unit may include a roller control unit that controls the rotation direction of the first roller and the position of the second roller. When the first sheet is discharged from the first discharge unit, the roller control unit arranges the second roller at the close position, and the first sheet moves in the discharge direction. The first roller may be bi-directionally rotated to move in the pulling direction. When the at least one sheet is discharged from the first discharge unit, the roller control unit may arrange the second roller at the separated position. When the sheet bundle is formed on the first tray, the roller control unit may rotate the first roller such that the sheet bundle moves in the discharge direction.

  According to the above configuration, when the first sheet is discharged from the first discharge unit, the roller control unit arranges the second roller in the proximity position, and after the first sheet is moved in the discharge direction, The first sheet is properly disposed on the first tray as the first roller is bi-directionally rotated to move in the pull-in direction. When the at least one sheet is discharged from the first discharger, the roller control places the second roller in the separated position so that the at least one sheet moves between the first roller and the second roller can do. Thus, the second outlet does not impede the movement of the at least one sheet. As a result, at least one sheet is smoothly placed on the first tray by the pull-in mechanism, and a sheet bundle is formed on the first tray. When the sheet bundle is formed on the first tray, the roller control unit rotates the first roller so that the sheet bundle moves in the discharge direction, so the sheet bundle on the first tray is moved by the second discharge unit. , Discharged onto the second tray.

  With regard to the above configuration, when the second sheet discharged from the first discharge unit at the end of the sheet bundle is held by the first tray, the tray drive unit is configured to move the second tray by a predetermined amount. You may only raise it.

  According to the above configuration, when the second sheet discharged from the first discharge unit at the end of the sheet bundle is held by the first tray, the tray drive unit raises the second tray by a predetermined amount. Because of this, the drop from the second discharge part to the second tray becomes smaller. Therefore, the sheet bundle is smoothly discharged from the first tray to the second tray.

  In the above configuration, the second tray raised by the tray driving unit may reach a second height position higher than the first height position.

  According to the above configuration, since the second tray raised by the tray driving unit reaches the second height position higher than the first height position, the drop from the second discharge unit to the second tray is It becomes smaller. Therefore, the sheet bundle is smoothly discharged from the first tray to the second tray.

  The above-described post-processing device can prevent sheets already arranged on the tray from being pushed out by the subsequent sheets.

1 is a schematic cross-sectional view of a portion of an exemplary aftertreatment device (first embodiment). FIG. 2 is a schematic block diagram of the post-processing device shown in FIG. 1; It is a schematic flowchart showing operation | movement of the ventilation control part of the post-processing apparatus shown by FIG. FIG. 3 is a schematic flowchart showing the operation of a tray control unit of the post-processing apparatus shown in FIG. 2; 5 is a timing chart of a sheet detection signal, a first control signal, a second control signal, and a tray detection signal. FIG. 3 is a schematic flowchart showing the operation of a tray control unit of the post-processing apparatus shown in FIG. 2; FIG. 7 is a schematic block diagram of an exemplary post-processing device (second embodiment). FIG. 8 is a schematic plan view of a first tray of the post-processing device shown in FIG. 7; It is a schematic flowchart showing operation | movement of the alignment control part of the post-processing apparatus shown by FIG. 5 is a timing chart of a sheet detection signal, a second control signal, a tray detection signal, and a matching control signal. It is a schematic block diagram of an exemplary post-processing device (third embodiment). It is a schematic flowchart showing operation | movement of the counter of the post-processing apparatus shown by FIG. It is a schematic flowchart showing operation | movement of the drive control part of the post-processing apparatus shown by FIG. It is a schematic flowchart showing operation | movement of the displacement control part of the post-processing apparatus shown by FIG. It is a schematic block diagram of an exemplary post-processing device (fourth embodiment). It is a schematic flowchart showing the production | generation operation | movement of the raise request of the counter of the post-processing apparatus shown by FIG. It is a schematic sectional drawing of an exemplary post-processing apparatus (5th Embodiment). FIG. 18 is a schematic block diagram of the post-processing device shown in FIG. 17; FIG. 19 is a schematic flowchart representing an operation of a pull-in control unit of the post-processing device shown in FIG. 18; FIG. 19 is a schematic flowchart showing the operation of the alignment control unit of the post-processing device shown in FIG. 18;

First Embodiment
The frictional force between the sheets is influenced by the material of the sheet and the image formed on the sheet. For example, if the sheets are pieces of paper for ink jet printing, high frictional forces are likely to occur between the sheets. In this case, the sheets already held in the tray are easily pushed out in the discharge direction by the subsequent sheets. The present inventors have developed a post-processing device having a mechanism that prevents the sheet already placed on the tray from being pushed out by the subsequent sheet, in order to solve the problem of pushing out the sheet in the discharge direction. In the first embodiment, an exemplary post-processing device is described.

  FIG. 1 is a schematic cross-sectional view of a portion of an exemplary aftertreatment device 100. The post-processing apparatus 100 is described with reference to FIG.

  An image forming apparatus (not shown) forms an image on a sheet (not shown) (image forming process). Thereafter, the sheet is sent from the image forming apparatus to the post-processing apparatus 100. The post-processing apparatus 100 forms a through hole in the sheet, places a staple on the sheet, and folds the sheet. The principle of the present embodiment is not limited to a specific process performed by the post-processing apparatus 100.

  The post-processing apparatus 100 includes a first discharge unit 210, a second discharge unit 220, a first tray 310, a second tray 320, and a blower unit 400. FIG. 1 conceptually shows the flow of the sheet from the first discharge unit 210 to the second discharge unit 220 by dotted arrows. The direction of the dotted arrow is referred to as the "ejection direction" in the following description. The direction opposite to the discharge direction is referred to as the "pull-in direction".

  The sheet supplied from the image forming apparatus reaches the first discharge unit 210 through a conveyance path (not shown) formed in the post-processing apparatus 100. The first discharge unit 210 includes two rollers 211 and 212. The sheet that has reached the first discharge unit 210 is nipped by the rollers 211 and 212. The roller 211 is driven by a motor (not shown). When the roller 211 is rotated by the motor, the sheet moves in the discharge direction. The roller 212 is rotated by the movement of the sheet in the discharge direction.

  The sheet discharged from the first discharge unit 210 is then delivered in the retraction direction by the second discharge unit 220 or a retraction mechanism (not shown). As a result, the sheet can be moved onto the first tray 310. Various techniques used for the known post-processing delivery mechanism may be used to feed sheets to the first tray 310. Thus, the principles of the present embodiment are not limited to any particular technique for feeding sheets to the first tray 310.

  The plurality of sheets are sequentially supplied from the image forming apparatus to the post-processing apparatus 100. As a result, the plurality of sheets are sequentially stacked on the first tray 310 to form a sheet bundle. The first tray 310 temporarily holds the sheet bundle. While the first tray 310 holds the sheet bundle, the post-processing apparatus 100 may perform a punching process on the sheet bundle on the first tray 310 or may perform a staple setting process. .

  The second discharge unit 220 includes two rollers 221 and 222 which rotate near the downstream end (downstream end in the discharge direction) of the first tray 310. The sheet bundle on the first tray 310 is sandwiched by the rollers 221 and 222. The roller 221 is driven by a motor (not shown). When the roller 221 is rotated by the motor, the sheet bundle moves in the discharge direction. The roller 222 is rotated by the movement of the sheet bundle in the discharge direction.

  The second tray 320 is located downstream of the first tray 310 in the discharge direction. Therefore, the sheet bundle sent out in the discharge direction by the second discharge unit 220 is supplied from the first tray 310 to the second tray 320.

  The lowermost sheet in the sheet bundle (that is, the sheet first supplied from the image forming apparatus to the post-processing apparatus 100) is referred to as a "first sheet" in the following description. While the first sheet is fed by the first discharge unit 210 in the discharge direction, a part of the lower surface of the first sheet appears on the second tray 320. While the first sheet is being delivered by the first delivery unit 210 in the delivery direction, the blower 400 blows air to form an air flow between the second tray 320 and the lower surface of the first sheet. FIG. 1 conceptually illustrates the air flow from the blower 400 by solid arrows. The air flow effectively reduces the frictional force between the second tray 320 and the first sheet, so that the first sheet can move smoothly in the discharge direction and the pull-in direction.

  When the first sheet is then held by the first tray 310, a portion of the first sheet covers the second tray 320. When the first discharge unit 210 finishes discharging the first sheet, the blower unit 400 stops blowing air, so the friction force between the first sheet and the second tray 320 is determined by the first sheet, When the first sheet is held by the first tray 310, it is higher than when moving in the discharge direction and the pull-in direction. Therefore, even if the subsequent sheet moving in the discharge direction comes in contact with the upper surface of the first sheet, the first sheet is less likely to move in the discharge direction. A general fan device may be used as the blower 400. For example, an axial fan, a centrifugal fan, a mixed flow fan or a cross flow fan may be used as the blower 400. The principle of the present embodiment is not limited to a specific air blower used as the air blower 400.

  FIG. 2 is a schematic block diagram of the post-processing apparatus 100. As shown in FIG. Post-processing apparatus 100 is further described with reference to FIGS. 1 and 2. The solid lines in FIG. 2 conceptually represent the signal transmission path. The dotted lines in FIG. 2 conceptually represent the force transmission path. The dashed line in FIG. 2 conceptually represents the detection operation.

  The post-processing apparatus 100 further includes a tray drive unit 500 and a control unit 600. Before the first sheet is discharged by the first discharge unit 210, the second tray 320 is disposed at the first height position. The tray driving unit 500 lowers the second tray 320 from the first height position under the control of the control unit 600. The tray drive unit 500 includes a motor (not shown) and a transmission mechanism (e.g., a combination of a belt and pulleys) designed to convert the rotational force of the motor into the vertical movement of the second tray 320 (not shown) And may be included. Alternatively, the tray drive unit 500 may include a cylinder device (not shown) connected to the second tray 320. The principle of the present embodiment is not limited to a specific mechanism of the tray drive unit 500.

  The control unit 600 controls not only the tray driving unit 500 but also the blower unit 400. Therefore, the control unit 600 can operate the tray driving unit 500 and the blower unit 400 at appropriate timing.

  The control unit 600 includes a sheet detection unit 610, an air flow control unit 620, a tray control unit 630, and a tray detection unit 640. The sheet detection unit 610 detects the first sheet discharged from the first discharge unit 210. The sheet detection unit 610 generates a sheet detection signal representing the start of the discharge of the first sheet and the end of the discharge of the first sheet. The sheet detection signal is output from the sheet detection unit 610 to the air flow control unit 620 and the tray control unit 630. The sheet detection unit 610 may be an optical sensor (a transmissive optical sensor or a reflective optical sensor) disposed downstream of the first discharge unit 210, or the sheet detection unit 610 of the first sheet from the first discharge unit 210. It may be another sensor that can detect the start and end of discharge. The principle of the present embodiment is not limited to a specific detection element used as the sheet detection unit 610. In the present embodiment, the detection unit is exemplified by the sheet detection unit 610. The detection signal is exemplified by the sheet detection signal.

  The blower control unit 620 generates a first control signal with reference to the sheet detection signal. The first control signal is output from the blower control unit 620 to the blower unit 400. The blower 400 blows out air in response to the first control signal.

  The tray control unit 630 generates a second control signal with reference to the sheet detection signal. The second control signal is output from the tray control unit 630 to the tray drive unit 500. The tray drive unit 500 lowers the second tray 320 from the first height position in response to the second control signal.

  The tray detection unit 640 may be a reflective optical sensor disposed at a position where it can detect the second tray 320 lowered from the first height position by a predetermined amount. When the second tray 320 descends from the first height position by a predetermined amount, the tray detection unit 640 detects the second tray 320 and generates a tray detection signal. The tray detection signal is output from the tray detection unit 640 to the tray control unit 630. The tray control unit 630 stops the generation of the second control signal in response to the tray detection signal.

  FIG. 3 is a schematic flowchart showing the operation of the blower control unit 620. The air flow control unit 620 is described with reference to FIGS. 2 and 3.

(Step S110)
The blower control unit 620 waits for a sheet detection signal. When the blower control unit 620 receives a sheet detection signal from the sheet detection unit 610, step S120 is performed.

(Step S120)
The blower control unit 620 generates a first control signal. The first control signal is output from the blower control unit 620 to the blower unit 400. The blower 400 blows out air in response to the first control signal. As a result, an air flow is formed between the second tray 320 and the first sheet. After the generation of the first control signal, step S130 is performed.

(Step S130)
If the blowing control unit 620 continues to receive the sheet detection signal (that is, if the sheet detection unit 610 detects the first sheet), step S120 is performed. If the blowing control unit 620 has not received the sheet detection signal (that is, if the sheet detection unit 610 has detected the first sheet), step S140 is performed.

(Step S140)
The blower control unit 620 stops the generation of the first control signal. As a result, the blower 400 stops.

  FIG. 4 is a schematic flowchart showing the operation of the tray control unit 630. The tray control unit 630 is described with reference to FIGS. 2 and 4.

(Step S210)
The tray control unit 630 waits for a sheet detection signal. When the tray control unit 630 receives a sheet detection signal from the sheet detection unit 610, step S220 is executed.

(Step S220)
If the tray control unit 630 continues to receive the sheet detection signal (that is, if the sheet detection unit 610 detects the first sheet), step S220 is repeated. If the tray control unit 630 has not received the sheet detection signal (ie, if the sheet detection unit 610 has detected the first sheet), step S230 is executed. When the first sheet is discharged from the first discharge unit 210 and arranged in the first tray 310, a part of the first sheet protrudes from the first tray 310. The area of the first sheet protruding from the first tray 310 is supported by the second tray 320 located downstream of the first tray 310 in the discharge direction.

(Step S230)
The tray control unit 630 generates a second control signal. The second control signal is output from the tray control unit 630 to the tray drive unit 500. The tray drive unit 500 lowers the second tray 320 from the first height position in response to the second control signal. As a result, a part of the first sheet held by the second tray 320 is lowered together with the second tray 320. Since the first sheet is separated downward from the discharge path of the subsequent sheet, the contact area between the first sheet and the subsequent sheet is very small. Therefore, the first sheet is less likely to be pushed out by the subsequent sheets. After the generation of the second control signal, step S240 is performed.

(Step S240)
If the tray control unit 630 has not received the tray detection signal from the tray detection unit 640, step S230 is executed. If the tray control unit 630 receives the tray detection signal from the tray detection unit 640, step S250 is executed.

(Step S250)
The tray control unit 630 stops the generation of the second control signal. As a result, the tray drive unit 500 and the second tray 320 stop.

  FIG. 5 is a timing chart of the sheet detection signal, the first control signal, the second control signal, and the tray detection signal. The relationship of these signals will be described with reference to FIGS.

  When the downstream end of the first sheet (the edge of the first sheet located downstream in the discharge direction) enters the detection position determined by the sheet detection unit 610, the voltage level of the sheet detection signal goes from low to high Change. The change of the sheet detection signal from a low voltage level to a high voltage level signifies the beginning of the discharge of the first sheet. The period in which the high voltage level is maintained means that the sheet detection unit 610 detects the first sheet. In the following description, a period during which a high voltage level is maintained is referred to as a "discharge operation period". When the upstream end of the first sheet (the edge of the first sheet positioned upstream in the discharge direction) passes the detection position determined by the sheet detection unit 610, the voltage level of the sheet detection signal goes from high to low. Change. A change from a high voltage level to a low voltage level of the sheet detection signal signifies the beginning of the end of the first sheet.

  In step S110 described with reference to FIG. 3, when the air flow control unit 620 detects a change from a low voltage level to a high voltage level of the sheet detection signal, the first control signal is generated by the air flow control unit 620. (Step S120). Generation of the first control signal is continued while the high voltage level of the sheet detection signal is maintained. In step S130 described with reference to FIG. 3, when the blower control unit 620 detects a change from a high voltage level to a low voltage level of the sheet detection signal, the generation of the first control signal is stopped. Therefore, the blower 400 can start blowing substantially simultaneously with the start of the discharge operation period. The blower 400 can stop the blower substantially simultaneously with the end of the discharge operation period.

  In step S220 described with reference to FIG. 4, when the tray control unit 630 detects a change from a high voltage level to a low voltage level of the sheet detection signal, a second control signal is generated by the tray control unit 630. Step S230. Therefore, the second tray 320 starts to descend substantially in synchronization with the end of the discharge operation period. When the second tray 320 enters the detection position determined by the tray detection unit 640, the voltage level of the tray detection signal changes from a low level to a high level. When the tray control unit 630 detects a change from a low voltage level to a high voltage level of the tray detection signal, the generation of the second control signal is stopped. Therefore, the second tray 320 can stop at the detection position determined by the tray detection unit 640.

  For the present embodiment, stopping the lowering of the second tray 320 depends on the tray detection unit 640. However, the tray control unit 630 may count the generation period of the second control signal. In this case, the tray control unit 630 may compare the generation period of the second control signal with a predetermined threshold to determine the timing for stopping the lowering of the second tray 320.

<Other features>
A designer can provide various features to the above-described post-processing apparatus 100. The features described below do not in any way limit the principles of the post-processing apparatus 100 described in connection with the above-described embodiments.

(Control based on the size of the first sheet)
If the first sheet temporarily held in the first tray 310 described with reference to FIG. 1 largely protrudes from the first tray 310 to the second tray 320, the subsequent sheet is the first sheet. The contact area between the sheet and the subsequent sheet increases. In this case, the first sheet is easily pushed out in the discharge direction by the subsequent sheet. On the other hand, if the first sheet does not extend much from the first tray 310 to the second tray 320, the contact area between the first sheet and the subsequent sheet is small. In this case, the first sheet is unlikely to be pushed out in the discharge direction by the subsequent sheets. That is, even if the second tray 320 is not lowered, the first sheet is appropriately held by the first tray 310. Control of the lowering of the second tray 320 based on the size of the first sheet will be described below.

  FIG. 6 is a schematic flowchart showing the operation of the tray control unit 630. The tray control unit 630 is described with reference to FIGS. 2, 5 and 6.

(Step S310)
The tray control unit 630 waits for the change from the low voltage level of the sheet detection signal to the high voltage level (see FIG. 5). When a change from the low voltage level to the high voltage level of the sheet detection signal occurs, the tray control unit 630 stores the time when the change from the low voltage level to the high voltage level of the sheet detection signal occurs. Thereafter, step S320 is performed.

(Step S320)
The tray control unit 630 waits for the change from the high voltage level of the sheet detection signal to the low voltage level (see FIG. 5). When a change from the high voltage level to the low voltage level of the sheet detection signal occurs, the tray control unit 630 stores the time when the change from the high voltage level to the low voltage level of the sheet detection signal occurs. Thereafter, step S330 is performed.

(Step S330)
The tray control unit 630 subtracts the data of the time stored in step S310 from the data of the time stored in step S320. As a result, the tray control unit 630 can calculate the time length of the discharge operation period described with reference to FIG. The tray control unit 630 multiplies the calculated time length by the discharge speed of the first sheet. The discharge speed of the first sheet is a preset fixed value. The tray control unit 630 can obtain data of the length of the first sheet in the discharge direction as a result of the multiplication. After the calculation of the length of the first sheet, step S340 is executed.

(Step S340)
The tray control unit 630 compares the length of the first sheet with a predetermined threshold. If the length of the first sheet exceeds the threshold, step S350 is performed. The predetermined threshold may be set such that step S350 is performed when the area exceeding half of the first sheet is out of the first tray 310. In other cases, the tray control unit 630 ends the process. Therefore, the second tray 320 is not unnecessarily lowered and is maintained at the first height position. That is, the post-processing device 100 does not waste power unnecessarily.

(Step S350)
The tray control unit 630 generates a second control signal. The second control signal is output from the tray control unit 630 to the tray drive unit 500. The tray drive unit 500 lowers the second tray 320 from the first height position in response to the second control signal. As a result, a part of the first sheet held by the second tray 320 is lowered together with the second tray 320. Since the first sheet is separated downward from the discharge path of the subsequent sheet, the contact area between the first sheet and the subsequent sheet is very small. As a result, the first sheet is less likely to be pushed out by the subsequent sheets. After the generation of the second control signal, step S360 is performed.

(Step S360)
If the tray control unit 630 has not received the tray detection signal from the tray detection unit 640, step S350 is executed. If the tray control unit 630 receives the tray detection signal from the tray detection unit 640, step S370 is executed.

(Step S370)
The tray control unit 630 stops the generation of the second control signal. As a result, the tray drive unit 500 and the second tray 320 stop.

  In the present embodiment, the tray control unit 630 calculates the length of the first sheet in the discharge direction from the sheet detection signal. However, the tray control unit 630 may receive information indicating the size of the first sheet from an image forming apparatus (not shown). For example, the image forming apparatus outputs, as information indicating the size of the first sheet, information of “A4 size” and “vertically oriented (that is, the long side of the first sheet is substantially parallel to the discharge direction)”. If so, the tray control unit 630 may generate a second control signal. On the other hand, the image forming apparatus outputs information of "A4 size" and "horizontal orientation (that is, the short side of the first sheet is substantially parallel to the discharge direction)" as the information indicating the size of the first sheet. Then, the tray control unit 630 may not generate the second control signal.

Second Embodiment
At least one sheet is ejected after the first sheet and stacked on the first sheet on the first tray. As a result, a sheet bundle is formed on the first tray. The first tray may have an alignment unit that performs an alignment process that aligns the positions of the first sheet and the subsequent sheet such that the edge of the subsequent sheet overlaps the edge of the first sheet. If the second tray is lowered before the aligning section finishes adjusting the position of the first sheet, the processing speed of the post-processing apparatus is higher than when these processes are performed in different periods. In a second embodiment, an exemplary post-processing apparatus having a high processing speed is described.

  FIG. 7 is a schematic block diagram of the post-processing apparatus 100. The post-processing apparatus 100 is described with reference to FIGS. 1, 2 and 7. The solid lines in FIG. 7 conceptually represent signal transmission paths. The dotted lines in FIG. 7 conceptually represent the force transmission path. The dashed line in FIG. 7 conceptually represents the detection operation.

  As in the first embodiment, the post-processing apparatus 100 includes a first discharge unit 210, a second discharge unit 220, a first tray 310, a second tray 320, a blower unit 400, and a tray drive unit 500. And. The description of the first embodiment is incorporated into these elements.

  The post-processing apparatus 100 further includes a control unit 600A. As in the first embodiment, the controller 600A controls the blower 400 and the tray driver 500. The description of the first embodiment is incorporated into the control of the blower 400 and the tray driver 500.

  The first tray 310 includes an alignment unit 311 that aligns the first sheet with the subsequent sheet. The control unit 600A controls the alignment unit 311 in addition to the blower unit 400 and the tray drive unit 500.

  As in the first embodiment, the control unit 600A includes an air flow control unit 620, a tray control unit 630, and a tray detection unit 640. The description of the first embodiment is incorporated into these elements.

  Control unit 600A further includes a sheet detection unit 610A and an alignment control unit 650. The sheet detection unit 610A includes a first sheet sensor 611 and a second sheet sensor 612. The first sheet sensor 611 corresponds to the sheet detection unit 610 described with reference to FIG. The description of the sheet detection unit 610 is incorporated in the first sheet sensor 611.

  The second sheet sensor 612 may be a reflective optical sensor attached to the first tray 310. When the first sheet reaches a predetermined position on the first tray 310, the second sheet sensor 612 generates a sheet detection signal. The sheet detection signal is output from the second sheet sensor 612 to the alignment control unit 650. The alignment control unit 650 generates an alignment control signal according to the sheet detection signal. The matching control signal is output from the matching control unit 650 to the matching unit 311. The alignment unit 311 adjusts the positions of the first sheet and the subsequent sheet in response to the alignment control signal.

  FIG. 8 is a schematic plan view of the first tray 310. As shown in FIG. The first tray 310 is described with reference to FIGS. 1, 7 and 8.

  The first tray 310 includes a support plate 312, two cursors 313 and 314, a stopper 315, and a motor (not shown) for driving the cursors 313 and 314. The support plate 312 supports the first sheet and the at least one sheet sequentially discharged by the first discharge unit 210 following the first sheet. The cursors 313 and 314 and the stopper 315 are erected from the upper surface of the support plate 312. The cursors 313, 314, the stopper 315, and the motors for driving the cursors 313, 314 form the alignment portion 311 described with reference to FIG.

  The stopper 315 is arranged such that the first sheet and the upstream end of the subsequent sheet (the edge located upstream in the discharge direction) collide with each other. The motor described above receives the alignment control signal described with reference to FIG. The motor rotates in response to the alignment control signal to reciprocate the cursors 313 and 314 in the direction orthogonal to the ejection direction. The techniques of various sheet alignment mechanisms provided in known post-processing devices may be applied to a conversion mechanism that converts the rotation of the motor into linear reciprocating movement of the cursors 313 and 314. Thus, the principles of the present embodiment are not limited to the particular structure of the conversion mechanism.

  When the first sheet is fed in the retraction direction by the second discharge unit 220, the upstream end of the first sheet collides with the stopper 315. As a result, the position of the first sheet in the discharge direction is determined. Thereafter, the cursors 313 and 314 move in the directions approaching each other. As a result, the lateral position of the first sheet in the direction orthogonal to the discharge direction is determined. With respect to this embodiment, the adjusting operation is illustrated by the approaching operation of the cursors 313, 314 when the first sheet enters the area between the cursors 313, 314.

  The cursors 313 and 314 then move away from one another. As a result, the sheet following the first sheet can enter the area between the cursors 313 and 314 without being interrupted by the cursors 313 and 314. Similar to the first sheet, the subsequent sheet collides with the stopper 315. As a result, the upstream end of the subsequent sheet overlaps the upstream end of the first sheet. Thereafter, the cursors 313 and 314 move in the directions approaching each other. As a result, the side edge of the subsequent sheet (ie, the edge substantially parallel to the discharge direction) overlaps the side edge of the first sheet, and a sheet bundle is formed on the first tray 310. With respect to the present embodiment, the alignment operation is illustrated by the approaching operation of the cursors 313, 314 when the subsequent sheet enters the area between the cursors 313, 314.

  As shown in FIG. 8, the detection position of the second sheet sensor 612 is formed near the stopper 315. When the upstream end of the first sheet enters the detection position of the second sheet sensor 612, the sheet detection signal is output from the second sheet sensor 612 to the alignment control unit 650. The alignment control unit 650 generates an alignment control signal according to the sheet detection signal. The alignment control signal is output from the alignment control unit 650 to the motor for driving the cursors 313 and 314. The motor reciprocates the cursors 313 and 314 in the direction orthogonal to the ejection direction according to the alignment control signal. As a result, the first sheet is disposed at a predetermined position on the support plate 312.

  FIG. 9 is a schematic flowchart showing the operation of the alignment control unit 650. The alignment control unit 650 is described with reference to FIGS. 7 to 9.

(Step S410)
The alignment control unit 650 waits for a sheet detection signal from the second sheet sensor 612. When the alignment control unit 650 receives a sheet detection signal from the second sheet sensor 612, step S420 is executed.

(Step S420)
The alignment control unit 650 generates an alignment control signal that causes the motor (not shown) of the alignment unit 311 to rotate in the first rotation direction. The matching control signal is output from the matching control unit 650 to the motor. The motor rotates in a first rotational direction in response to the alignment control signal. When the motor rotates in the first rotation direction, the cursors 313 and 314 move in the directions approaching each other. After the generation of the alignment control signal, step S430 is performed.

(Step S430)
The alignment control unit 650 determines whether the amount of rotation of the motor exceeds a predetermined threshold. The alignment control unit 650 may determine the amount of rotation of the motor using a signal from an encoder attached to the motor. Alternatively, the alignment control unit 650 may count the number of pulses of the alignment control signal to determine the amount of rotation of the motor. Furthermore, alternatively, the alignment control unit 650 may measure the output period of the alignment control signal and estimate the amount of rotation of the motor based on the output period. The principle of this embodiment is not limited at all depending on how the amount of rotation of the motor is determined. If the motor rotation amount exceeds the threshold, step S440 is executed. Otherwise, step S420 is performed.

(Step S440)
The alignment control unit 650 generates an alignment control signal that causes the motor of the alignment unit 311 to rotate in a second rotation direction opposite to the first rotation direction. The matching control signal is output from the matching control unit 650 to the motor. The motor rotates in the second rotation direction in response to the alignment control signal. When the motor rotates in the second rotational direction, the cursors 313 and 314 move away from each other. After the generation of the alignment control signal, step S450 is performed.

(Step S450)
The alignment control unit 650 determines whether the amount of rotation of the motor exceeds a predetermined threshold. If the amount of rotation of the motor exceeds the threshold, the alignment control unit 650 ends the process. Otherwise, step S440 is performed.

  FIG. 10 is a timing chart of sheet detection signals from the first sheet sensor 611 and the second sheet sensor 612, the second control signal, the tray detection signal, and the alignment control signal. The relationship between these signals will be described with reference to FIGS. 1, 5 and 7-10.

  The sheet detection signal, the second control signal, and the tray detection signal from the first sheet sensor 611 are the same as the sheet detection signal, the second control signal, and the tray detection signal described with reference to FIG. 5. Therefore, the description of the first embodiment is incorporated into these signals.

  Prior to the entry of the first sheet into the detection position of the second sheet sensor 612 (see FIG. 8), the first sheet is moved in the retraction direction by the second discharge unit 220 (see FIG. 1). Therefore, the sheet detection signal of the first sheet sensor 611 is delayed from the high voltage level to the low voltage level (that is, the time when the first discharge unit 210 finishes discharging the first sheet) by a predetermined period. The sheet detection signal of the second sheet sensor 612 changes from a low voltage level to a high voltage level. The high voltage level of the sheet detection signal of the second sheet sensor 612 means that the second sheet sensor 612 detects the first sheet on the first tray 310.

  When the sheet detection signal of the second sheet sensor 612 changes from the low voltage level to the high voltage level, step S420 described with reference to FIG. 9 is performed. The alignment control unit 650 outputs an alignment control signal for rotating the motor (not shown) of the alignment unit 311 in the first rotation direction for a predetermined period (step S420). Thereafter, the alignment control unit 650 outputs an alignment control signal for rotating the motor of the alignment unit 311 in the second rotation direction for a predetermined period (step S440). As shown in FIG. 10, the tray detection signal changes from a low voltage level to a high voltage level before the output of these matching control signals is finished. This means that the tray drive unit 500 with respect to the second tray 320 is driven so that the second tray 320 reaches the detection position of the tray detection unit 640 before the alignment unit 311 finishes adjusting the position of the first sheet. It means that the speed is set. The second tray 320 reaches the detection position of the tray detection unit 640 within a period in which the alignment unit 311 is required to adjust the position of the first sheet. It does not cause a decrease in speed. Therefore, the post-processing apparatus 100 can maintain a high processing speed.

Third Embodiment
The control unit may control the second discharge unit. In a third embodiment, an exemplary post-processing device having the function of controlling the second ejector is described.

  FIG. 11 is a schematic block diagram of the post-processing apparatus 100. The post-processing apparatus 100 is described with reference to FIGS. 1, 10 and 11. The solid lines in FIG. 11 conceptually represent signal transmission paths. The dotted lines in FIG. 11 conceptually represent the force transmission path. The dashed line in FIG. 11 conceptually represents the detection operation.

  As in the first embodiment, the post-processing apparatus 100 includes a first discharge unit 210, a second discharge unit 220, a first tray 310, a second tray 320, a blower unit 400, and a tray drive unit 500. And. The description of the first embodiment is incorporated into these elements.

  The second discharge unit 220 includes a roller driving unit 223 and a roller displacement unit 224 in addition to the rollers 221 and 222. The roller drive unit 223 may be a motor that drives the lower roller 221. The upper roller 222 is reciprocally moved up and down by the roller displacement portion 224. When the roller displacement portion 224 moves the roller 222 downward, the roller 222 approaches the roller 221. When the roller displacement portion 224 moves the roller 222 upward, the roller 222 separates from the roller 221. The sheet bundle is formed in the gap between the rollers 221 and 222. The roller displacement portion 224 may include a motor (not shown) and an arm member (not shown) connected to the motor and the roller 222. In this case, the arm member swings around the rotation axis of the motor, and the roller 222 attached to the tip of the arm member can be displaced up and down. Alternatively, the roller displacement portion 224 may be a cylinder device that moves the roller 222 up and down. The principle of the present embodiment is not limited to the specific structure of the roller displacement portion 224. For the present embodiment, the first roller is exemplified by the roller 221. The second roller is illustrated by roller 222. The proximity position is exemplified by the position of the roller 222 in proximity to the roller 221. The remote position is illustrated by the position of roller 222 away from roller 221.

  The post-processing apparatus 100 further includes a control unit 600B. As in the first embodiment, the control unit 600B includes an air flow control unit 620, a tray control unit 630, and a tray detection unit 640. The description of the first embodiment is incorporated into these elements.

  As in the second embodiment, the control unit 600B further includes an alignment control unit 650. The description of the second embodiment is incorporated in the alignment control unit 650.

  The control unit 600B further includes a sheet detection unit 610B and a roller control unit 660. As in the second embodiment, the sheet detection unit 610B includes a first sheet sensor 611 and a second sheet sensor 612. The description of the second embodiment is incorporated into these elements.

  The sheet detection unit 610B further includes a counter 613. The counter 613 receives sheet bundle information from the image forming apparatus IFA. The sheet bundle information represents the total number of sheets output from the image forming apparatus IFA to the post-processing apparatus 100. When the first sheet is discharged, the first sheet sensor 611 outputs the pulse shown in FIG. 10 as a sheet detection signal. Similarly, even when the sheet following the first sheet passes the detection position of the first sheet sensor 611, the first sheet sensor 611 outputs a pulse as a sheet detection signal. The counter 613 counts pulses included in the sheet detection signal output from the first sheet sensor 611. When the number of pulses counted matches the total number of sheets represented by the sheet bundle information, the counter 613 generates a discharge request. The discharge request is output from the counter 613 to the roller control unit 660.

  The roller control unit 660 includes a drive control unit 661 and a displacement control unit 662. The sheet detection signal generated by the first sheet sensor 611 is output not only to the tray control unit 630 and the air flow control unit 620 but also to the roller control unit 660. The drive control unit 661 controls the roller drive unit 223 according to the sheet detection signal output from the first sheet sensor 611, and rotates the roller 221. The sheet detection signal generated by the second sheet sensor 612 is output not only to the alignment control unit 650 but also to the roller control unit 660. The drive control unit 661 controls the roller drive unit 223 with reference to the sheet detection signal generated by the second sheet sensor 612, and stops the roller 221. The displacement control unit 662 controls the roller displacement unit 224 in accordance with the sheet detection signal output from the first sheet sensor 611 and the second sheet sensor 612.

  The drive control unit 661 receives not only the sheet detection signal output from the first sheet sensor 611 but also the discharge request output from the counter 613. The drive control unit 661 controls the roller drive unit 223 in response to the discharge request.

  The displacement control unit 662 receives not only the sheet detection signal output from the second sheet sensor 612 but also the discharge request output from the counter 613. The displacement control unit 662 controls the roller displacement unit 224 in response to the discharge request.

  FIG. 12 is a schematic flowchart showing the operation of the counter 613. The counter 613 is described with reference to FIGS. 11 to 12.

(Step S510)
The counter 613 waits for sheet bundle information. When the counter 613 receives sheet bundle information from the image forming apparatus IFA, step S520 is executed.

(Step S520)
The counter 613 sets the counter value to “0”. Thereafter, step S530 is executed.

(Step S530)
The counter 613 waits for the pulse of the sheet detection signal output from the first sheet sensor 611. When the counter 613 receives a pulse, step S540 is performed.

(Step S540)
The counter 613 adds the value of “1” to the counter value. Thereafter, step S550 is performed.

(Step S550)
The counter 613 compares the counter value with the total number of sheets represented by the sheet bundle information. If the counter value matches the total number of sheets, step S560 is executed. Otherwise, step S530 is performed.

(Step S560)
The counter 613 generates a discharge request. The discharge request is output from the counter 613 to the drive control unit 661 and the displacement control unit 662. The drive control unit 661 controls the roller drive unit 223 in response to the discharge request. The roller drive unit 223 rotates the roller 221 so that the sheet bundle moves in the discharge direction. The displacement control unit 662 lowers the roller 222 in response to the discharge request. As a result, the sheet bundle is pinched by the rollers 221 and 222. As a result, the rotational force of the roller 221 is effectively transmitted to the sheet bundle, and the sheet bundle can be smoothly moved in the discharge direction.

  FIG. 13 is a schematic flowchart showing the operation of the drive control unit 661. The drive control unit 661 will be described with reference to FIGS. 10, 11 and 13.

(Step S610)
The drive control unit 661 waits for the change from the low voltage level of the sheet detection signal output from the first sheet sensor 611 to the high voltage level (see FIG. 10). When the sheet detection signal output from the first sheet sensor 611 changes from the low voltage level to the high voltage level, step S620 is performed.

(Step S620)
The drive control unit 661 controls the roller drive unit 223 to rotate the roller 221 such that the first sheet moves in the discharge direction. Thereafter, step S630 is performed.

(Step S630)
The drive control unit 661 waits for the change from the high voltage level of the sheet detection signal output from the first sheet sensor 611 to the low voltage level (see FIG. 10). When the sheet detection signal output from the first sheet sensor 611 changes from the high voltage level to the low voltage level, step S640 is performed. If the sheet detection signal output from the first sheet sensor 611 maintains a high voltage level, step S620 is performed.

(Step S640)
The drive control unit 661 controls the roller drive unit 223 to rotate the roller 221 such that the first sheet moves in the pull-in direction. Thereafter, step S650 is performed.

(Step S650)
The drive control unit 661 waits for the change from the low voltage level of the sheet detection signal output from the second sheet sensor 612 to the high voltage level (see FIG. 10). When the sheet detection signal output from the second sheet sensor 612 changes from the low voltage level to the high voltage level, step S660 is performed. If the sheet detection signal output from the second sheet sensor 612 maintains a low voltage level, step S640 is performed.

(Step S660)
The drive control unit 661 controls the roller drive unit 223 to stop the roller 221. Thereafter, step S670 is performed.

(Step S670)
The drive control unit 661 waits for a discharge request. When the drive control unit 661 receives the discharge request from the counter 613, step S680 is executed.

(Step S680)
The drive control unit 661 controls the roller drive unit 223 to rotate the roller 221 for a predetermined period so that the sheet bundle moves in the discharge direction. As a result, the sheet bundle is discharged from the first tray 310 to the second tray 320.

  FIG. 14 is a schematic flowchart showing the operation of the displacement control unit 662. The displacement control unit 662 is described with reference to FIGS. 1, 11, 13 and 14.

(Step S710)
The displacement control unit 662 waits for the change from the low voltage level of the sheet detection signal output from the first sheet sensor 611 to the high voltage level (see FIG. 10). When the sheet detection signal output from the first sheet sensor 611 changes from the low voltage level to the high voltage level, step S720 is performed.

(Step S720)
The displacement control unit 662 controls the roller displacement unit 224 to lower the roller 222. As a result, the first sheet is pinched by the rollers 221 and 222. Since step S720 is synchronized with steps S620 and S640, the first sheet is fed in the discharge direction by the rotation of the roller 221 and then moved in the retraction direction. After the lowering of the roller 222, step S730 is performed.

(Step S730)
The displacement control unit 662 waits for the change from the low voltage level of the sheet detection signal output from the second sheet sensor 612 to the high voltage level (see FIG. 10). When the sheet detection signal output from the second sheet sensor 612 changes from the low voltage level to the high voltage level, step S740 is performed.

(Step S740)
The displacement control unit 662 controls the roller displacement unit 224 to raise the roller 222. Subsequent sheets discharged from the first discharge unit 210 after the first sheet are stacked between the rollers 221 and 222. After the elevation of the roller 222, step S750 is performed.

(Step S750)
The displacement control unit 662 waits for a discharge request. When the displacement control unit 662 receives the discharge request from the counter 613, step S760 is executed.

(Step S760)
The displacement control unit 662 controls the roller displacement unit 224 to lower the roller 222. As a result, the sheet bundle is pinched by the rollers 221 and 222. Since step S 760 is synchronized with step S 680, the sheet bundle is fed in the discharge direction by the rotation of the roller 221 and is discharged from the first tray 310 to the second tray 320.

Fourth Embodiment
The second tray may ascend just before the stack of sheets is discharged from the first tray to the second tray. As a result of the elevation of the second tray, the drop from the second outlet to the second tray is reduced. Therefore, the sheet bundle is smoothly discharged from the first tray to the second tray. In a fourth embodiment, an exemplary post-processing apparatus having a vertically reciprocating second tray is described.

  FIG. 15 is a schematic block diagram of the post-processing apparatus 100. The post-processing apparatus 100 is described with reference to FIGS. 1, 2 and 15. The solid lines in FIG. 15 conceptually represent signal transmission paths. The dotted lines in FIG. 15 conceptually represent the force transmission path. The dashed line in FIG. 15 conceptually represents the detection operation.

  As in the first embodiment, the post-processing apparatus 100 includes a first discharge unit 210, a second discharge unit 220, a first tray 310, a second tray 320, a blower unit 400, and a tray drive unit 500. And. The description of the first embodiment is incorporated into these elements.

  The post-processing apparatus 100 further includes a control unit 600C. As in the first embodiment, the control unit 600C includes a blower control unit 620. The description of the first embodiment is incorporated in the air flow control unit 620. As in the second embodiment, the control unit 600C further includes an alignment control unit 650. The description of the second embodiment is incorporated in the alignment control unit 650. As in the third embodiment, the controller 600C further includes a roller controller 660. The description of the third embodiment is incorporated in the roller control unit 660.

  Control unit 600C further includes sheet detection unit 610C, tray control unit 630C, and tray detection unit 640C. As in the second embodiment, the sheet detection unit 610C includes a first sheet sensor 611 and a second sheet sensor 612. The description of the second embodiment is incorporated into these elements.

  The sheet detection unit 610C further includes a counter 613C. Similar to the third embodiment, the counter 613C receives sheet bundle information from the image forming apparatus IFA, and generates a discharge request. The roller control unit 660 controls the second discharge unit 220 in response to the discharge request. The description of the third embodiment is incorporated in the control of the second discharge unit 220 according to the generation of the discharge request and the discharge request.

  The counter 613C generates a rising request in addition to the discharging request. The increase request is output from the counter 613C to the tray control unit 630C. The tray control unit 630C controls the tray driving unit 500 in response to the lifting request to lift the second tray 320 by a predetermined amount. As in the above-described embodiment, the tray control unit 630C controls the tray driving unit 500 to lower the second tray 320 according to the sheet detection signal output from the first sheet sensor 611. The description of the above embodiment is incorporated in the control for lowering the second tray 320.

  The tray detection unit 640C includes a lower tray sensor 641 and an upper tray sensor 642. The lower tray sensor 641 corresponds to the tray detection unit 640 described with reference to FIG. When the second tray 320 descends and enters the detection position of the lower tray sensor 641, the lower tray sensor 641 generates a tray detection signal. The tray detection signal is output from the lower tray sensor 641 to the tray control unit 630C. The tray control unit 630C controls the tray driving unit 500 in accordance with the tray detection signal to stop the lowering of the second tray 320.

  The upper tray sensor 642 sets a detection position above the detection position of the lower tray sensor 641. When the second tray 320 ascends and enters the detection position of the upper tray sensor 642, the upper tray sensor 642 generates a tray detection signal. The tray detection signal is output from the upper tray sensor 642 to the tray control unit 630C. The tray control unit 630C controls the tray driving unit 500 in response to the tray control signal to stop the second tray 320 from rising. As a result of the elevation of the second tray 320, the second tray 320 approaches the rollers 221 and 222 of the second discharge unit 220. Therefore, the sheet bundle on the first tray 310 is smoothly discharged to the second tray 320. The detection position of the upper tray sensor 642 (that is, the height position at which the second tray 320 is stopped to rise) is referred to as the “second height position” in the following description. The second height position may be above the height position (that is, the first height position) of the second tray 320 shown in FIG.

  The tray detection signal generated by the upper tray sensor 642 is output not only to the tray control unit 630C but also to the counter 613C. The counter 613C generates the above-described discharge request in response to the tray detection signal. Therefore, the sheet bundle on the first tray 310 is discharged to the second tray 320 after the second tray 320 reaches the second height position. Therefore, the sheet bundle is smoothly discharged from the first tray 310 to the second tray 320.

  FIG. 16 is a schematic flow chart showing an operation of generating a rising request of the counter 613C. The operation of generating a rising request will be described with reference to FIGS. 1, 12, and 15 to 16.

(Step S551)
The operation of generating a rising request may be the operation in step S550 described with reference to FIG. Therefore, after step S540, step S551 is executed. The counter 613C compares the counter value with the total number of sheets represented by the sheet bundle information. If the counter value is less than the total number of sheets, step S530 is executed. Otherwise, step S553 is performed.

(Step S553)
When step S553 is executed, the count value matches the total number of sheets. That is, the second sheet discharged from the first discharge unit 210 at the end of the sheet bundle is held by the first tray 310. At this time, the counter 613C generates a rising request. The increase request is output from the counter 613C to the tray control unit 630C. The tray control unit 630C controls the tray driving unit 500 to raise the second tray 320 in response to the rising request. After generation of the ascent request, step S555 is performed.

(Step S555)
The counter 613C waits for a tray detection signal. When the counter 613C receives a tray detection signal from the upper tray sensor 642, step S560 is executed.

Fifth Embodiment
The pull-in mechanism is used to move, in the pull-in direction, the subsequent sheet discharged from the first discharge unit after the first sheet is stored in the first tray. Subsequent sheets moved in the retraction direction by the retraction mechanism will be properly accommodated in the first tray. In a fifth embodiment, an exemplary post-processing apparatus with a retraction mechanism is described.

  FIG. 17 is a schematic cross-sectional view of the post-processing apparatus 100. The post-processing device 100 is described with reference to FIG.

  As in the first embodiment, the post-processing apparatus 100 includes a first discharge unit 210, a second discharge unit 220, a first tray 310, and a second tray 320. The description of the first embodiment is incorporated into these elements.

  The post-processing apparatus 100 includes a stapler 700 and a retraction mechanism 800. The stapler 700 places staples on the sheet bundle formed on the first tray 310. The pull-in mechanism 800 moves the subsequent sheet discharged from the first discharge unit 210 after the first sheet is stored in the first tray 310 in the pull-in direction.

  The retraction mechanism 800 includes a rotating shaft 810, a paddle arm 820, and a paddle drive (not shown). The paddle drive may be a motor. The paddle drive may further include a transmission mechanism for transmitting the rotation of the motor to the rotating shaft 810. The rotating shaft 810 is rotated by a motor. The paddle arm 820 extends tangential to the circumferential surface of the rotating shaft 810. As rotating shaft 810 rotates, paddle arm 820 can contact the top surface of the sheet bundle. The paddle arm 820 can resiliently flex when in contact with the top surface of the sheet bundle. The friction force between the paddle arm 820 and the upper surface of the subsequent sheet discharged from the first discharge portion 210 and the restoring force accompanying the elastic deformation of the paddle arm 820 move the subsequent sheet in the retraction direction, It is disposed on the tray 310.

  FIG. 18 is a schematic block diagram of the post-processing apparatus 100. The post-processing apparatus 100 is further described with reference to FIGS. 12 and 16 to 18.

  As in the first embodiment, the post-processing apparatus 100 further includes a blower 400 and a tray driver 500. The description of the first embodiment is incorporated into these elements.

  The post-processing apparatus 100 further includes a control unit 600D. As in the first embodiment, the control unit 600D includes a blower control unit 620. The description of the first embodiment is incorporated in the air flow control unit 620. As in the third embodiment, the control unit 600D further includes a roller control unit 660. The description of the third embodiment is incorporated in the roller control unit 660. As in the fourth embodiment, the control unit 600D further includes a tray control unit 630C and a tray detection unit 640C. The description of the fourth embodiment is incorporated into these elements.

  Control unit 600D further includes sheet detection unit 610D, alignment control unit 650D, and retraction control unit 670. The sheet detection unit 610D includes a first sheet sensor 611 and a second sheet sensor 612. The description of the second embodiment is incorporated into these elements.

  The sheet detection signal generated by the first sheet sensor 611 is output not only to the air flow control unit 620, the tray control unit 630C, and the roller control unit 660, but also to the pull-in control unit 670. The pull-in control unit 670 controls the paddle drive unit 830 of the pull-in mechanism 800 in accordance with the sheet detection signal received from the first sheet sensor 611.

  The sheet detection unit 610D further includes a counter 613D. The counter 613D includes a main processing unit 614, a discharge request generation unit 615, an elevation request generation unit 616, and an operation request generation unit 617. The main processing unit 614 executes steps S510 to S540 described with reference to FIG. In addition, the main processing unit 614 executes step S551 and step S555 described with reference to FIG. In step S560, the discharge request generation unit 615 receives a command from the main processing unit 614, and generates a discharge request. The discharge request is output from the discharge request generation unit 615 to the roller control unit 660. In step S553, the rise request generation unit 616 receives a command from the main processing unit 614, and generates a rise request. The elevation request is output from the elevation request generation unit 616 to the tray control unit 630C. The main processing unit 614 also gives a command to the operation request generation unit 617 in synchronization with the command to the elevation request generation unit 616. The operation request generation unit 617 generates an operation request according to a command from the main processing unit 614. The operation request is output to the stapler 700. The stapler 700 operates in response to the operation request, and staples the sheet bundle on the first tray 310. Since the placement of the staples into the sheet bundle is performed at the same time as the raising of the second tray 320, the post-processing apparatus 100 can maintain a high processing speed.

  FIG. 19 is a schematic flowchart showing the operation of the retraction control unit 670. The drive control unit 661 will be described with reference to FIGS. 10 and 17 to 19.

(Step S810)
The pull-in control unit 670 waits for the change from the high voltage level of the sheet detection signal output from the first sheet sensor 611 to the low voltage level (see FIG. 10). The change from the high voltage level to the low voltage level of the sheet detection signal means that the first sheet has passed the first discharge unit 210. When the sheet detection signal output from the first sheet sensor 611 changes from the high voltage level to the low voltage level, step S620 is performed.

(Step S820)
The pull-in control unit 670 waits for the change from the high voltage level of the sheet detection signal output from the first sheet sensor 611 to the low voltage level (see FIG. 10). The change from the high voltage level to the low voltage level of the sheet detection signal means that the subsequent sheet has passed the first discharge unit 210. When the sheet detection signal output from the first sheet sensor 611 changes from the high voltage level to the low voltage level, step S830 is performed.

(Step S830)
The retraction control unit 670 starts clocking. Thereafter, step S840 is executed.

(Step S840)
The pull-in control unit 670 controls the paddle drive unit 830. As a result, the rotating shaft 810 rotates, and the paddle arm 820 slides in the retraction direction with respect to the upper surface of the subsequent sheet. As a result, the subsequent sheet can move in the pull-in direction. Thereafter, step S850 is executed.

(Step S850)
The lead-in control unit 670 compares the counted time (that is, the counted value) from step S 830 with a predetermined first threshold. If the time count value exceeds the first threshold, step S860 is executed. Otherwise, step S840 is performed.

(Step S860)
The pull-in control unit 670 generates a matching request. The matching request is output from the pull-in control unit 670 to the matching control unit 650D. The matching control unit 650D controls the matching unit 311 in response to the matching request. After generation of the alignment request, step S870 is performed.

(Step S870)
The pull-in control unit 670 waits for the change from the high voltage level of the sheet detection signal output from the first sheet sensor 611 to the low voltage level (see FIG. 10). The change from the high voltage level to the low voltage level of the sheet detection signal means that the subsequent sheet has passed the first discharge unit 210. If the sheet detection signal output from the first sheet sensor 611 changes from the high voltage level to the low voltage level, step S840 is performed. Otherwise, step S 880 is performed.

(Step S 880)
The lead-in control unit 670 compares the counted time (that is, the counted value) from step S 830 with a predetermined second threshold. The second threshold is set to a value larger than the first threshold. If the time count value exceeds the second threshold, the pull-in control unit 670 determines that the sheet bundle is formed on the first tray 310, and ends the process. Otherwise, step S870 is performed.

  FIG. 20 is a schematic flowchart showing the operation of the alignment control unit 650D. Alignment control unit 650D will be described with reference to FIGS. 8, 9, 18 and 20.

(Step S455)
After step S450 described with reference to FIG. 9, step S455 is performed. The alignment control unit 650D waits for an alignment request from the pull-in control unit 670. When alignment control unit 650D receives the alignment request from pull-in control unit 670, step S460 is executed.

(Step S460)
The alignment control unit 650D generates an alignment control signal that causes the motor (not shown) of the alignment unit 311 to rotate in the first rotation direction. The matching control signal is output from the matching control unit 650D to the motor. The motor rotates in a first rotational direction in response to the alignment control signal. When the motor rotates in the first rotation direction, the cursors 313 and 314 (see FIG. 8) move in the direction approaching each other. As a result, the edge of the sheet superimposed on the first sheet overlaps the edge of the first sheet. After the generation of the alignment control signal, step S430 is performed. For the present embodiment, the alignment operation is illustrated by the approaching operation of the cursors 313, 314 at step 460.

(Step S465)
Alignment control unit 650D determines whether the amount of rotation of the motor has exceeded a predetermined threshold. The alignment control unit 650D may determine the amount of rotation of the motor using a signal from an encoder attached to the motor. Alternatively, the alignment control unit 650D may count the number of pulses of the alignment control signal to determine the amount of rotation of the motor. Further alternatively, alignment control unit 650D may measure the output period of the alignment control signal and estimate the amount of rotation of the motor based on the output period. The principle of this embodiment is not limited at all depending on how the amount of rotation of the motor is determined. If the amount of rotation of the motor exceeds the threshold, step S470 is executed. Otherwise, step S460 is performed.

(Step S470)
The alignment control unit 650D generates an alignment control signal that causes the motor of the alignment unit 311 to rotate in a second rotation direction opposite to the first rotation direction. The matching control signal is output from the matching control unit 650D to the motor. The motor rotates in the second rotation direction in response to the alignment control signal. When the motor rotates in the second rotational direction, the cursors 313 and 314 move away from each other. After the generation of the matching control signal, step S475 is performed.

(Step S475)
Alignment control unit 650D determines whether the amount of rotation of the motor has exceeded a predetermined threshold. If the amount of rotation of the motor exceeds the threshold, the alignment control unit 650D executes step S480. Otherwise, step S470 is performed.

(Step S480)
The alignment control unit 650D starts clocking. Thereafter, step S485 is executed.

(Step S485)
The alignment control unit 650D waits for an alignment request from the pull-in control unit 670. If alignment control unit 650D receives an alignment request from pull-in control unit 670, step S460 is executed. Otherwise, step S490 is performed.

(Step S490)
Alignment control unit 650D compares the counted time from step S480 (that is, the counted value) with a predetermined threshold. If the count value exceeds the threshold, the alignment control unit 650D determines that the sheet bundle is formed on the first tray 310, and ends the process. Otherwise, step S485 is performed.

  The present invention is suitably applied to a post-processing apparatus that performs predetermined processing subsequent to image forming processing by an image forming apparatus.

100....... ----- second discharge part 221 ............... roller (first roller)
222 ··················································
310.............. ... the second tray 400 ............... blowing section 500 ............... tray drive unit 600,600A~600D ·· ... Control units 610, 610A to 610D ..... Sheet detection unit (detection unit)
620 ··· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·. Unit 660 ······························································································································· ······································· Image forming device

Claims (9)

A post-processing apparatus that performs predetermined processing subsequent to image forming processing by an image forming apparatus,
A first discharge unit that discharges the first sheet;
A first tray that temporarily holds the first sheet discharged by the first discharge unit;
A second tray located downstream of the first tray in the discharge direction of the first sheet;
A tray drive unit for lowering the second tray from the first height position;
A blower configured to form an air flow between the second tray and the lower surface of the first sheet discharged by the first discharge unit;
And a control unit that controls the blower unit and the tray driving unit.
The control unit
(I) A blower control unit for blowing the air from the blower unit over a period synchronized with a discharge operation period from the start to the end of discharge of the first sheet by the first discharge unit;
(Ii) After the discharge operation period, the tray drive unit includes a tray control unit that lowers the second tray from the first height position. The control unit includes a detection unit that detects the first sheet discharged from the first discharge unit, and generates a detection signal indicating the start and the end of the discharge.
The post-processing apparatus according to claim 1, wherein the air flow control unit controls the air flow unit according to the detection signal. If the first sheet is longer than the predetermined length in the discharge direction, the tray control unit lowers the second tray from the first height position,
The post-processing apparatus according to claim 1, wherein the second tray is maintained at the first height position if the first sheet is equal to or less than the predetermined length in the discharge direction. The tray control unit uses the detection signal to calculate the length of the first sheet in the discharge direction, and compares the calculated length with a predetermined threshold value.
If the calculated length exceeds the predetermined threshold, the tray control unit lowers the second tray from the first height position,
The post-processing apparatus according to claim 2, wherein the second tray is maintained at the first height position if the calculated length is equal to or less than the predetermined threshold. The first discharge unit sequentially discharges at least one sheet following the first sheet,
An alignment unit that aligns the at least one sheet with the first sheet to form a sheet bundle so that the first tray has an edge of the at least one sheet overlapping an edge of the first sheet; Including
The tray control unit lowers the second tray before the alignment unit completes the adjustment operation of adjusting the position of the first sheet on the first tray in the direction orthogonal to the discharge direction. The post-processing apparatus according to any one of claims 1 to 4. The at least one sheet is further moved in a pulling direction opposite to the discharging direction, and further provided with a pulling mechanism arranged on the first tray.
The control unit includes a pull-in control unit that controls the pull-in mechanism to move the at least one sheet in the pull-in direction, and an alignment control unit that controls the alignment operation of the alignment unit.
When the at least one sheet is moved in the pull-in direction under control of the pull-in control unit and disposed on the first tray, the alignment control unit executes the alignment operation in the alignment unit. The post-processing apparatus according to claim 5. The apparatus further comprises a second discharge unit that discharges the sheet bundle from the first tray to the second tray,
The second discharge unit includes a first roller, and a second roller that moves between a proximity position close to the first roller and a separation position away from the first roller,
The control unit includes a roller control unit that controls the rotation direction of the first roller and the position of the second roller,
When the first sheet is discharged from the first discharge unit, the roller control unit arranges the second roller at the close position, and the first sheet moves in the discharge direction. Rotating the first roller in both directions so as to move in the pulling direction;
When the at least one sheet is discharged from the first discharge unit, the roller control unit arranges the second roller at the separated position;
The post-processing apparatus according to claim 6, wherein when the sheet bundle is formed on the first tray, the roller control unit rotates the first roller so that the sheet bundle moves in the discharge direction. When the second sheet discharged from the first discharge unit among the sheet bundle is held by the first tray, the tray drive unit raises the second tray by a predetermined amount. The post-processing apparatus according to any one of items 4 to 7. 9. The post-processing apparatus according to claim 8, wherein the second tray raised by the tray driving unit reaches a second height position higher than the first height position.

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