JP2022131156A - Sheet loading device and post-processing device - Google Patents

Abstract

To suppress friction between a guide member protruding in a discharge direction and a sheet.SOLUTION: A sheet loading device 120 includes a discharge part 31 that discharges a sheet, a loading tray 61 on which a sheet discharged by the discharge part 31 is loaded, an air blowing part 91 that blows air, a guide member 81 that, when the sheet is discharged, protrudes to a protruding position P2 above the loading tray 61 to be in contact with a lower surface of the sheet to guide the sheet to be discharged and retreats to a retreat position upstream of the protruding position P2 in the discharge direction at a predetermined timing, and a control part 2 that controls the protrusion and retreat of the guide member 81 and air blowing by the air blowing part 91. The guide member 81 has a built-in air duct 93 connected to the air blowing part 91 and also has, at its top, an air-blowing outlet 81U opened for the air flowing through the air duct 93. The control part 2 blows air toward the lower surface of the sheet while the sheet is discharged.SELECTED DRAWING: Figure 6

Description

The present invention relates to a sheet stacking device for stacking discharged sheets and a post-processing device.

2. Description of the Related Art A sheet stacking device that stacks sheets on which images are formed by an image forming apparatus is known. The sheet stacking device includes, for example, a discharge unit (such as a pair of discharge rollers) that discharges sheets, a stacking tray that stacks the discharged sheets, and an elevating mechanism that lifts and lowers the stacking tray according to the amount of stacked sheets. Prepare. A post-processing apparatus is also known that includes a post-processing section that performs post-processing on sheets on which images have been formed, and the above-described sheet stacking device that stacks the sheets that have undergone post-processing.

In such a sheet stacking device, since the top surface of the stacking tray is located at a position lower than the discharge section, the leading edge of the discharged sheet may hang down. In this case, the sheet may drop onto the stacking tray in a curled state, or the leading edge of the sheet may collide with the stacking tray, thereby hindering the sheet ejection and stacking. Therefore, conventionally, it has been proposed to provide a guide member projecting in the ejection direction below the sheet to be ejected (for example, Patent Documents 1 to 4).

JP 2019-147673 A JP 2019-127355 A JP-A-2000-289909 JP 2005-263475 A

However, in the case of the inkjet method, the sheet may be conveyed in a wet state. In that case, it is conceivable that ink adheres to the guide member as the paper rubs against the guide member. In addition, when a sheet with high wettability is used, ink tends to adhere to the guide member due to high frictional resistance. Moreover, the load at the time of transportation becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet stacking device and a post-processing device capable of suppressing friction between a guide member projecting in the discharge direction and a sheet.

In order to solve the above-described problems, a sheet stacking apparatus according to the present invention includes a discharge section that discharges sheets, a stacking tray on which the sheets discharged by the discharge section are stacked, a blower section that blows air, and the When the sheet is ejected, it protrudes to a protruding position above the stacking tray and contacts the lower surface of the sheet to guide the ejection of the sheet, and retreats to a retraction position upstream of the protruding position in the ejection direction at a predetermined timing. and a control unit for controlling the extension and retraction of the guide member and the blowing of air by the blowing unit, wherein the guide member incorporates an air duct connected to the blowing unit, and the upper surface of the guide member opens to the air duct. and the controller blows the air toward the lower surface of the sheet while the sheet is being discharged.

The sheet stacking device includes a detection unit that detects the sheet on the upstream side in the discharge direction of the discharge unit, and the control unit detects the protrusion position at the timing when the leading edge of the sheet is detected by the detection unit. may be configured to control the guide member to protrude into the

The controller may control the air blower so as to start air blowing at a timing when the leading edge of the sheet is detected by the detector.

The controller may control the guide member so as to retract to the retracted position at the timing when the trailing edge of the sheet is detected by the detector.

The controller may control the air blower so as to stop blowing air when the trailing edge of the sheet is detected by the detector.

The control unit may control the air blowing unit to blow air only when the number of sheets discharged by the discharging unit at one time is less than a predetermined number.

Further, the post-processing apparatus according to the present invention includes a post-processing unit that performs one or more post-processing such as stapling, shift processing, and center-folding on the sheets on which images have been formed; and a sheet stacking device for stacking the post-processed sheets on the stacking tray.

According to the present invention, it is possible to suppress the friction between the guide member projecting in the discharge direction and the sheet.

1 is a perspective view showing the appearance of an image forming system according to an embodiment of the invention; FIG. 1 is a front view schematically showing the internal configuration of a post-processing device according to one embodiment of the present invention; FIG. 1 is a perspective view of an elevating mechanism according to one embodiment of the present invention; FIG. 1 is a front view schematically showing the configuration of a sheet stacking device according to one embodiment of the present invention; FIG. 1 is a perspective view of a sheet stacking device according to one embodiment of the present invention; FIG. 1 is a front view schematically showing the configuration of a sheet stacking device according to one embodiment of the present invention; FIG. 1 is a perspective view of a sheet stacking device according to one embodiment of the present invention; FIG. 1 is a block diagram showing an electrical configuration of an image forming system according to an embodiment of the invention; FIG. 4 is a flowchart of sheet stacking control according to an embodiment of the present invention;

An image forming system 100 according to an embodiment of the present invention will be described below with reference to the drawings.

First, the overall configuration of image forming system 100 will be described. FIG. 1 is a perspective view showing the appearance of an image forming system 100. As shown in FIG. In the following description, the Fr side in FIG. 1 is defined as the front side (front side) of the image forming system 100, and the left and right directions are based on the direction when the image forming system 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and rear, respectively.

Image forming system 100 includes image forming apparatus 1 and post-processing apparatus 110 . The image forming apparatus 1 is, for example, a multifunction machine including a printer, a scanner, and a document feeder. The document conveying device conveys the document along a conveying path passing through the reading position of the scanner. The scanner is a flatbed image scanner that reads an original and generates image data. A printer forms an image on a sheet by an inkjet method, an electrophotographic method, or the like. The post-processing device 110 performs post-processing on the sheet conveyed from the printer and discharges the sheet.

Next, the configuration of post-processing device 110 will be described (see FIGS. 1 and 2). FIG. 2 is a front view schematically showing the internal configuration of the post-processing device 110. As shown in FIG. The post-processing device 110 includes a substantially rectangular parallelepiped housing 21 . A receiving port 22 for receiving sheets conveyed from the image forming apparatus 1 is provided in the upper portion of the right side plate of the housing 21 .

The left side plate of the housing 21 is provided with a recess 23 recessed rightward. When viewed from the left, the recess 23 has a substantially rectangular shape with long sides extending in the vertical direction and short sides extending in the front-rear direction. The concave portion 23 includes a bottom portion 23B formed to the right of the left side plate, front and rear side wall portions 23S formed between the front and rear ends of the bottom portion 23B and the left side plate, and an upper end portion of the bottom portion 23B and the left side plate. and a lower wall portion 23L formed between the lower end portion of the bottom portion 23B and the left side plate.

A discharge portion 31 for discharging the sheet is provided above the concave portion 23 . Below the discharge section 31, a sheet stacking device 120, which will be described later, is provided. An upper discharge portion 44 is provided on the top plate portion of the housing 21 . A transport path 41 is provided inside the housing 21 from the inlet 22 to the discharge section 31 , and a branch path 42 is provided that branches off from the transport path 41 and reaches an upper discharge section 44 . A transport roller 43 is provided in the transport path 41 .

The upper discharge section 44 includes discharge rollers and a discharge port. A stacking tray 45 whose position is fixed is provided to the left of the upper discharge section 44 .

The discharge section 31 includes a discharge port 32 and a discharge roller 33 provided on the right side of the discharge port 32 . The discharge roller 33 includes a drive roller 33D driven by a motor (not shown) and a driven roller 33N driven by the drive roller 33D. The driving roller 33D can be pressed against and separated from the driven roller 33N.

A processing tray 51 (an example of a post-processing section) and a stapling device 54 (an example of a post-processing section) are provided below the transport path 41 . The processing tray 51 is provided so as to incline downward to the right from the discharge port 32, and a sheet bundle to be stapled by the stapling device 54 is stacked thereon. A left end portion of the processing tray 51 rotatably supports the driven roller 33N of the discharge roller 33 . The stapling device 54 is provided on the right side of the processing tray 51, and staples the right end portion of the sheet bundle stacked on the processing tray 51 (stapling process). Note that the post-processing device 110 may be provided with a center-folding device (an example of a post-processing unit) that folds a sheet (not shown).

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 are movable along the width direction of the sheet (the direction intersecting the discharge direction Y). The sheets on the processing tray 51 are aligned in the width direction by synchronously moving the pair of side fences 52 in the direction toward each other. Further, the pair of side fences 52 moves together in the width direction, thereby moving the sheet bundle in the width direction (shift processing). A sheet receiving plate 53 is provided at the right end of the processing tray 51 . The sheets are aligned in the discharge direction Y by abutting the sheet receiving plate 53 on the right end of the sheet bundle stacked on the processing tray 51 .

[Sheet stacking device]
Next, the configuration of the sheet stacking device 120 will be described. 3 is a perspective view of the lifting mechanism 63. FIG. 4 and 6 are front views schematically showing the configuration of the sheet stacking device 120. FIG. 5 and 7 are perspective views of the sheet stacking device 120. FIG.

The sheet stacking device 120 includes a discharge unit 31 for discharging sheets, a stacking tray 61 on which the sheets discharged by the discharge unit 31 are stacked, a blower unit 91 for blowing air, and an upper side of the stacking tray 61 when the sheets are discharged. a guide member 81 that guides the discharge of the sheet by projecting to a protruding position P2 and coming into contact with the lower surface of the sheet, and retracts at a predetermined timing to a retracting position P1 that is upstream of the protruding position P2 in the discharge direction; The guide member 81 incorporates an air duct 93 connected to the air blower 91, and has an opening on the upper surface for air flowing through the air duct 93. 81U, and the control unit 2 blows air toward the lower surface of the sheet while the sheet is being discharged.

[Load tray]
The upper surface of the stacking tray 61 is inclined upward toward the downstream side in the sheet ejection direction Y. As shown in FIG. The stacking tray 61 is provided to the left of the recess 23 . Brackets 62 for coupling the stacking tray 61 and belts 66, which will be described later, are provided at the right end portions of the front and rear sides of the stacking tray 61 (see FIG. 3). A slit (not shown) is formed in the vertical direction at a portion corresponding to the bracket 62 of the bottom portion 23B or the side wall portion 23S of the recess 23, and the bracket 62 penetrates the slit.

[lifting mechanism]
The lifting mechanism 63 (see FIG. 3) includes a drive shaft 64, a driven shaft 65 provided below the drive shaft 64, and belts 66 provided at two front and rear positions. The lifting mechanism 63 is provided on the right side of the recess 23 . Sprockets 64S are provided at two locations on the front and rear of the drive shaft 64, and a drive gear 64G is provided at one end of the drive shaft 64. As shown in FIG. Driving force is transmitted to the driving gear 64G via a motor and a reduction gear train (not shown). Two sprockets 65S are provided on the driven shaft 65 corresponding to the sprockets 64S of the drive shaft 64 . A sprocket 64S of the drive shaft 64 and a sprocket 65S of the driven shaft 65 are wound around an endless belt 66 having teeth formed on the inner peripheral surface thereof. A bracket 62 of the stacking tray 61 is fixed to the outer peripheral surface of the belt 66 . When the driving force is transmitted to the driving gear 64G, the front and rear belts 66 synchronously circulate in the same direction, and the loading tray 61 moves up and down as the belts 66 run.

[Upper surface detection unit]
A top detection portion 68 is provided on the upper portion of the recess 23 of the housing 21 (see FIG. 2). The upper surface detection unit 68 is, for example, a transmissive or reflective optical sensor. In the case of the transmissive type, a light emitting portion is provided on one of the side wall portions 23S before and after the concave portion 23, and a light receiving portion is provided on the other side wall portion 23S (not shown). In the case of the reflective type, one side wall portion 23S is provided with a light emitting portion and a light receiving portion, and the other side wall portion 23S is provided with a reflecting mirror (not shown). In either type, if the height of the upper surface of the stacked sheets (the upper surface of the uppermost sheet) is higher than the height of the light path of the light emitting unit, the light is blocked by the sheet, so the light receiving unit cannot receive light. In this case, the upper surface detection unit 68 outputs a signal of the first level (hereinafter referred to as a light shielding signal). On the other hand, when the height of the upper surface of the stacked sheets is less than the height of the optical path of the light emitting section, the light is not blocked by the sheet and the light is received by the light receiving section. In this case, the upper surface detector 68 outputs a second level signal (hereinafter referred to as a light receiving signal).

[Guide member]
The guide member 81 (see FIG. 4) is a tubular member with a hollow structure that is curved in an upwardly convex arc shape. A cross section perpendicular to the longitudinal direction of the guide member 81 is rectangular. The downstream end of the guide member 81 in the discharge direction Y is closed and tapered. The guide members 81 are provided at two locations in the width direction that intersects the ejection direction Y (see FIG. 5). The housing 21 is provided with a casing 82 that accommodates the upstream portion of the guide member 81 in the discharge direction Y. As shown in FIG. The guide member 81 is movable between a retracted position P1 (see FIGS. 4 and 5) accommodated in the casing 82 and a projecting position P2 (see FIGS. 6 and 7) projecting upward from the stacking tray 61. As shown in FIG. Movements of the two guide members 81 are synchronized. A gap is formed between the end portion of the guide member 81 on the downstream side in the discharge direction Y and the upper surface of the stacking tray 61 at the projecting position P2.

Rack teeth 81R are formed along the longitudinal direction of the guide member 81 on the lower surface of the guide member 81 . The guide driving portion 84 has a pinion gear 85 that meshes with the rack teeth 81R, a motor 86, and a transmission mechanism 87 that transmits the rotation of the motor 86 to the pinion gear 85. Motor 86 is a stepping motor.

At the retracted position P1, the guide member 81 rests on the inner surface of the casing 82 and the pinion gear 85 (see FIG. 4). When the pinion gear 85 is rotated counterclockwise in FIG. 6 by driving the motor 86, the guide member 81 projects from the retracted position P1 toward the projecting position P2 (see FIG. 6). A roller 88 having a diameter smaller than that of the driven roller 33N is provided on the rotating shaft of the driven roller 33N of the discharge roller 33 . When the guide member 81 protrudes from the retracted position P1 toward the projecting position P2, the lower surface of the guide member 81 is guided by the roller 88, and the guide member 81 is placed on the pinion gear 85 and the roller 88 at the projecting position P2. be placed. When the pinion gear 85 rotates clockwise, the guide member 81 retreats from the projecting position P2 toward the retreating position P1.

The retraction detection unit 75 is, for example, a photointerrupter, and detects the guide member 81 by blocking the optical path with the guide member 81 when the guide member 81 is positioned at the retraction position P1. The retracted position P1 is the home position of the guide member 81 .

[Blower]
A blower section 91 is provided on the lower right side of the casing 82 (see FIG. 4). The blower section 91 includes a blower 92 and an air duct 93 . The blower 92 is, for example, a centrifugal fan, an axial fan, or the like. The right end of the casing 82 is provided with an opening 82A. The right end of the guide member 81 is provided with an opening 81A. The air duct 93 is a tube having a smaller diameter than the hollow portion of the guide member 81 and is inserted into the guide member 81 via the opening 82A of the casing 82 and the opening 81A of the guide member 81 . A right end of the air duct 93 is connected to the blower 92 . The length of the air duct 93 is determined so that the left end of the air duct 93 is positioned inside the guide member 81 even when the guide member 81 moves to the projecting position P2. The upper surface of the guide member 81 is provided with one or more air outlets 81U. The position of the air blowing port 81U is determined so that the air blowing port 81U is located downstream of the discharge roller 33 in the discharge direction Y when the guide member 81 is positioned at the projecting position P2.

[Sheet detector]
A sheet detection unit 76 is provided upstream of the transport roller 43 in the discharge direction Y (see FIG. 4). The sheet detection unit 76 is, for example, a transmissive or reflective optical sensor. When the sheet passes the position of the sheet detection section 76, the sheet blocks the light, so the sheet detection section 76 outputs a signal of the first level (hereinafter referred to as a light shielding signal). On the other hand, when the sheet does not pass the position of the sheet detection section 76, the sheet does not block the light, so the sheet detection section 76 outputs a second level signal (hereinafter referred to as a light reception signal). When the leading edge of the sheet (end on the downstream side in the discharge direction Y) passes the position of the sheet detection unit 76, the light reception signal is switched to the light shielding signal. On the other hand, when the trailing edge portion of the sheet (the edge portion on the upstream side in the discharge direction Y) passes the position of the sheet detecting portion 76, the light blocking signal is switched to the light receiving signal.

[Electrical configuration]
FIG. 8 is a block diagram showing the electrical configuration of the image forming system 100. As shown in FIG. A control unit 2 is provided in the image forming apparatus 1 . The control unit 2 includes a calculation unit 2P and a storage unit 2M. The calculation unit 2P is, for example, a CPU (Central Processing Unit). The storage unit 2M includes storage media such as ROM (Read Only Memory), RAM (Random Access Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit 2P performs various processes by reading out and executing the control programs stored in the storage unit 2M. Note that the control unit 2 may be implemented by an integrated circuit that does not use software.

The control unit 2 is connected to the upper surface detection unit 68 , the sheet detection unit 76 , the lifting mechanism 63 , the guide driving unit 84 , the blower unit 91 and the operation unit 19 . The operation unit 19 is provided on the upper front side of the image forming apparatus 1 (see FIG. 1). The operation unit 19 includes a display panel, a touch panel provided on the display surface of the display panel, and a keypad adjacent to the display panel (not shown). The control unit 2 causes the display panel to display a screen representing an operation menu of the image forming apparatus 1 and the post-processing apparatus 110, and controls each unit of the image forming apparatus 1 and the post-processing apparatus 110 according to the operation detected by the touch panel and the keypad. to control.

Next, the operation of the sheet stacking device 120 will be described. FIG. 9 is a flowchart of sheet stacking control. When the image forming system 100 is powered on, the controller 2 executes sheet stacking control according to the flow chart of FIG.

First, the control section 2 determines whether or not a print job has started (step S01). When determining that the print job has not started (step S01: NO), the control section 2 repeats the process of step S01. On the other hand, if it is determined that the print job has started (step S01: YES), the control section 2 determines whether or not the sheet detection section 76 has detected the leading edge of the sheet. If it is determined that the leading edge of the sheet has not been detected (step S03: NO), the control section 2 repeats the process of step S03. On the other hand, when determining that the leading edge of the sheet has been detected (step S03: YES), the control section 2 drives the discharge roller 33 of the discharge section 31 (step S05).

Next, the control unit 2 determines whether or not the number of sheets discharged by the discharging unit 31 at one time is one (step S07). When it is determined that the number of sheets to be discharged at one time is one (step S07: YES), the control section 2 causes the air blowing section 91 to start blowing air (step S09), and moves the guide member 81 to the projecting position P2. (step S11).

Specifically, the control unit 27 drives the motor 86 of the guide driving unit 84, and drives the motor 86 by a predetermined number of pulses after the retraction detection unit 75 stops detecting the guide member 81. 81 is projected from the retracted position P1 to the projecting position P2 (see FIGS. 6 and 7). The control unit 2 causes the drive roller 33D of the discharge roller 33 to be pressed against the driven roller 33N to rotate the drive roller 33D clockwise in FIG. The first sheet is conveyed along the upper surface of the guide member 81 by the conveying roller 43 and the discharge roller 33 .

Next, the controller 2 determines whether or not the trailing edge of the sheet has been detected by the sheet detector 76 (step S13). When determining that the trailing edge of the sheet has been detected, the controller 2 causes the air blower 91 to stop blowing air, and retracts the guide member 81 to the retracted position P1.

Next, the control section 2 determines whether or not the print job has ended (step S15). If it is determined that the print job has not ended (step S15: NO), the control section 2 repeats the processes after step S03. On the other hand, if it is determined that the print job has ended (step S15: YES), the control section 2 repeats the processes from step S01 onward.

Next, processing after step S21 will be described. In step S21, the control section 2 executes the post-processing designated by the print job. Here, an example of executing stapling processing as post-processing will be described.

After projecting the guide member 81 from the retracted position P1 to the projected position P2, the controller 2 separates the driving roller 33D from the driven roller 33N. The first sheet is conveyed along the upper surface of the guide member 81 by the conveying roller 43 .

Next, the controller 2 causes the driven roller 33N to press the drive roller 33D at the timing when the trailing edge of the sheet passes through the nip portion of the transport roller 43, and rotates the drive roller 33D counterclockwise. Then, the sheet is switched back and conveyed to the processing tray 51 . After conveying the sheet until the trailing edge of the sheet contacts the sheet receiving plate 53 of the processing tray 51, the control unit 2 stops the rotation of the discharge roller 33 and separates the driving roller 33D from the driven roller 33N.

Subsequently, the control unit 2 conveys the second and subsequent sheets to the processing tray 519 in the same procedure as for the first sheet, stops the rotation of the discharge roller 33, and moves the drive roller 33D away from the driven roller 33n. The sheets are separated from each other and aligned in the width direction by a pair of side fences 52.例文帳に追加

After conveying the number of sheets specified in the print job to the processing tray 51, the control unit 2 retracts the guide member 81 to the retracted position P1 and presses the driving roller 33D against the driven roller 33n to sandwich the sheet bundle. , the stapling device 54 staples the bundle of sheets.

Next, the control unit 2 determines whether or not the number of sheet bundles is less than a predetermined number (step S23). If it is determined that the number of sheets is less than the predetermined number (step S23: YES), the controller 2 proceeds to step S25. On the other hand, when it is determined that the number of sheet bundles is equal to or greater than the predetermined number (step S23: NO), the control section 2 proceeds to the process of step S31.

In step S25, the controller 2 causes the air blower 91 to start blowing air, causes the guide member 81 to protrude to the projecting position P2 (step S27), and rotates the driving roller 33D clockwise. It is discharged along 81.

Next, the control unit 2 determines whether or not the trailing edge of the sheet bundle has been detected by the sheet detection unit 76 (step S29). When determining that the trailing edge of the sheet bundle has been detected, the controller 2 causes the air blower 91 to stop blowing air, and retracts the guide member 81 to the retracted position P1. After the trailing edge of the sheet bundle is discharged, the sheet bundle drops onto the stacking tray 61 due to gravity. At this time, since the guide member 81 is retracted from above the stacking tray 61, it does not interfere with the falling sheet bundle.

, the processing after step S31 will be described. In step S<b>31 , the control unit 2 projects the guide member 81 to the projecting position P<b>2 and rotates the drive roller 33</b>D clockwise.

Next, the control unit 2 determines whether or not the trailing edge of the sheet bundle has been detected by the sheet detection unit 76 (step S33). When determining that the trailing edge of the sheet bundle has been detected, the controller 2 retracts the guide member 81 to the retracted position P1.

According to the sheet stacking device 120 according to the present embodiment described above, the discharge section 31 that discharges the sheets, the stacking tray 61 on which the sheets discharged by the discharge section 31 are stacked, and the blower section 91 that blows air. When the sheet is ejected, it protrudes to the projecting position P2 above the stacking tray 61 and contacts the lower surface of the sheet to guide the ejection of the sheet, and at a predetermined timing moves to the retreating position P1 upstream of the projecting position P2 in the ejection direction. A guide member 81 that retracts, and a control unit 2 that controls the extension and retraction of the guide member 81 and the air blowing of the air blowing unit 91. The guide member 81 incorporates an air duct 93 connected to the air blowing unit 91. The control unit 2 has an open air blowing port 81U for air flowing through the air duct 93, and the control unit 2 blows air toward the lower surface of the sheet while the sheet is being discharged. According to this configuration, since air is blown out from the air outlet 81U, friction between the guide member 81 projecting in the discharge direction Y and the sheet can be suppressed.

Further, according to the sheet stacking device 120 according to this embodiment,
A detection unit (sheet detection unit 76) that detects the sheet on the upstream side in the discharge direction Y of the discharge unit 31 is provided, and the control unit 2 protrudes to the projecting position P2 at the timing when the leading edge of the sheet is detected by the detection unit. Since the guide member 81 is controlled in such a manner, the guide member 81 can be protruded at the timing corresponding to the passage of the sheet.

Further, according to the sheet stacking apparatus 120 according to the present embodiment, the control unit 2 controls the air blowing unit 91 so as to start blowing air at the timing when the leading edge of the sheet is detected by the detection unit. It is possible to start blowing air at a timing that matches the time.

Further, according to the sheet stacking device 120 according to the present embodiment, the controller 2 controls the guide member 81 so as to retract to the retracted position P1 at the timing when the trailing edge of the sheet is detected by the detector. The guide member 81 can be retracted at a timing that matches the discharge of the sheet.

Further, according to the sheet stacking apparatus 120 according to the present embodiment, the controller 2 controls the blower 91 so as to stop blowing air when the trailing edge of the sheet is detected by the detector. It is possible to stop the air blowing at the timing matched with the discharge.

Further, according to the sheet stacking device 120 according to the present embodiment, the control unit 2 controls the blower unit 91 so as to blow air only when the number of sheets discharged by the discharge unit 31 at one time is equal to or less than a predetermined number of sheets. Therefore, energy consumption can be suppressed when the air blowing effect is poor.

The above embodiment may be modified as follows.

In the above embodiment, the blowing of air is stopped before the guide member 81 is retracted. However, the blowing of air is continued until the guide member 81 reaches the retracted position P1. After that, the ventilation may be stopped. With this configuration, it is possible to suppress friction between the guide member 81 and the sheet while the guide member 81 moves from the projecting position P2 to the retracted position P1.

In the above embodiment, an example was given in which the air is blown only when the number of sheets discharged by the discharge unit 31 at one time is less than the predetermined number of sheets. You can change it. For example, when the number of sheets ejected by the ejection unit 31 at one time is equal to or greater than a predetermined number, the air blower 91 may be controlled to increase the amount of air compared to when the number of sheets is less than the predetermined number. With this configuration, it is possible to suppress the friction between the guide member 81 and the sheets even if the number of sheets discharged by the discharge unit 31 at one time increases.

In the above-described embodiment, an example is shown in which air blowing is started and the guide member 81 protrudes at the timing when the downstream end of the sheet in the discharge direction Y is detected by the sheet detection unit 76. The timing at which the member 81 is projected may be the timing after a predetermined time has elapsed since the sheet detection unit 76 detected the downstream end in the discharge direction Y of the sheet. Also, the timing for starting air blowing and the timing for projecting the guide member 81 may be different.

In the above-described embodiment, the blowing of the air is stopped and the guide member 81 is retracted at the timing when the sheet detection unit 76 detects the upstream end of the sheet in the Y direction. The blowing of air may be stopped and the guide member 81 may be retracted at the timing when the upstream end is discharged from the discharging portion 31 . For example, the air blowing may be stopped and the guide member 81 may be retracted after a predetermined time has elapsed since the sheet detection unit 76 detected the upstream end of the sheet in the discharge direction Y. FIG.

2 control unit 31 discharge unit 51 processing tray (post-processing unit)
54 stapling device (post-processing unit)
61 stacking tray 76 sheet detection unit (detection unit)
81 Guide member 81U Air blower port 91 Air blower 110 Post-processing device 120 Sheet stacking device

Claims (7)

a discharge unit for discharging the sheet;
a stacking tray on which the sheets discharged by the discharge unit are stacked;
a blower that blows air;
When the sheet is ejected, it protrudes to a protruding position above the stacking tray and contacts the lower surface of the sheet to guide the ejection of the sheet, and at a predetermined timing moves to a retreat position upstream of the protruding position in the ejection direction. a retracting guide member;
A control unit that controls the extension and retraction of the guide member and the blowing of the blowing unit,
The guide member has a built-in air duct connected to the air blowing part, and has an air blowing port that opens on the upper surface and flows through the air duct,
The sheet stacking apparatus, wherein the control unit blows the air toward the lower surface of the sheet while the sheet is being discharged. a detection unit that detects the sheet on the upstream side in the discharge direction of the discharge unit;
2. The sheet stacking apparatus according to claim 1, wherein the controller controls the guide member so as to protrude to the projecting position at the timing when the leading edge of the sheet is detected by the detector. 3. The sheet stacking apparatus according to claim 2, wherein the control section controls the air blowing section to start blowing air at a timing when the leading edge of the sheet is detected by the detection section. 4. The sheet stacking apparatus according to claim 2, wherein the controller controls the guide member so as to retract to the retracted position at the timing when the trailing edge of the sheet is detected by the detector. Device. 5. The control unit according to any one of claims 2 to 4, wherein the control unit controls the air blow unit so as to stop blowing air when the trailing edge of the sheet is detected by the detection unit. sheet stacker. 6. The controller according to any one of claims 1 to 5, wherein the control unit controls the air blower so as to blow air only when the number of sheets discharged by the discharge unit at one time is less than a predetermined number. A sheet stacking device according to the paragraph. a post-processing unit that performs one or more post-processing of stapling, shifting, and center-folding on the sheets on which images have been formed;
7. A post-processing apparatus, comprising: a sheet stacking device according to claim 1, which stacks the sheets post-processed by the post-processing section on the stacking tray.

Images