JP2000272806A - Sheet loading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To meet a requirement for high speed by quickly forming an accepting preparation for sheets in a designated delivery tray in a configuration having a plurality of independently driven delivery trays relative to one sheet delivery port. SOLUTION: In using an upper side delivery tray 1 capable of upwardly shunting to the upper portion of a sheet delivery port E2, a lower side delivery tray 2 serving as a high-volume delivery tray is shunted to a lower limit position detected by a lower limit position detecting sensor SN7. In the case when the lower side delivery trays 2 has low sheet load capacity or removes the sheets, a standby position serving as a home position for the lower side delivery tray 2 detected by a standby position detecting sensor SN9 is controlled as a shunting position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine or a printer, or a sheet stacking apparatus such as a sheet post-processing apparatus provided with the image forming apparatus.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 8-26579 discloses a sheet post-processing apparatus as a sheet stacking apparatus.
This paper post-processing apparatus has one paper output tray on the side of the apparatus. The sheets on which images have been formed received from the image forming apparatus are temporarily stacked on a tray in the apparatus and subjected to binding processing. And a function of directly discharging the paper to the paper discharge tray without performing the binding process. There is also known a paper discharge tray which can be moved up and down to discharge a large amount of paper.

However, since all the sheet groups or sheet bundle groups are stacked on one discharge tray without distinction, there is a problem that, for example, when there are a plurality of users, the distinction cannot be made. In recent years, the usage forms of image forming apparatuses have been diversified.
As a result, the function of sorting discharged sheets in an image forming apparatus, a sheet post-processing apparatus, and the like has become increasingly important.

The above problem can be somewhat solved by providing another sheet discharge port and a proof tray (discharge tray) corresponding thereto in addition to a discharge tray having a large discharge structure. it can. However, even in this case, since each sheet discharge port and the paper discharge tray correspond one-to-one, the sorting mode, the binding mode, and the like are limited, and when outputting to the proof tray, the benefits of high added value such as the binding processing cannot be enjoyed. The problem remains.

Japanese Patent Application Laid-Open No. Hei 7-228401 discloses that in order to cope with a higher speed of the image forming apparatus, two sheet discharge ports are respectively made to correspond to a discharge tray, and these discharge trays can be raised and lowered independently. The provided configuration is disclosed. When the upper discharge tray is used as a large-volume discharge tray, the lower discharge tray is retracted downward when the upper discharge tray is lowered to a predetermined position. Japanese Patent Application Laid-Open No. 8-73107 discloses a sorter in which a plurality of discharge trays can be raised and lowered simultaneously, the intervals between the respective discharge trays can be individually changed, and the stacking amount of sheets can be arbitrarily increased. An apparatus is disclosed.
Each of the paper discharge trays can move through a sheet discharge port, and returns to an initial position when a sheet is removed.

[0006]

Problems to be Solved by the Invention
In the technique described in Japanese Patent Laid-Open No. 1-2005, there is a problem that the configuration is complicated because a sheet discharge configuration exists for each discharge tray. The technique described in Japanese Patent Application Laid-Open No. 8-73107 has a problem that the stroke of the large-volume discharge configuration is small and the discharge capacity at the time of large-volume discharge is not sufficient because all the trays are connected.

In a configuration in which a plurality of output trays are independently driven to correspond to one sheet output port, it is necessary to retract the lower output tray when the upper output tray corresponds to the sheet output port. In order to make the lower discharge tray correspond to the sheet discharge port, it is necessary to retract the upper discharge tray above the sheet discharge port. Also, when using the lower discharge tray as a large-volume discharge tray, it is safer to retract the retreat position as far as possible from the sheet discharge port in consideration of the stacking capacity when retracting it. When the lower paper discharge tray is designated as the next paper discharge destination, the moving distance becomes large, and a problem arises that it takes time until the paper discharge receiving posture is established.

Accordingly, the present invention has a large-volume paper discharge configuration with a large capacity and ensures the safety of avoiding a collision between the paper discharge trays, while minimizing the moving distance to the sheet discharge port. The main purpose is to provide a sheet stacking device that can respond to high speed.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a sheet discharge port for discharging sheets, a plurality of paper discharge trays which can be independently raised and lowered, and In a sheet stacking apparatus having control means for individually associating these discharge trays with the sheet discharge ports, the discharge tray may include an upper discharge tray capable of retracting above the sheet discharge ports, and an upper discharge tray. When the tray is used, it is divided into a lower discharge tray that retreats below the sheet discharge port, and a lower discharge tray is used below the sheet discharge port when the lower discharge tray is used as a large discharge tray. A lower limit position is provided and a lower limit position detecting means for detecting the lower limit position is provided, and a standby position of the lower discharge tray as a home position is provided between the sheet discharge port and the lower limit position. And a standby position detecting means for detecting the standby position is provided. When the amount of stacked sheets on the lower discharge tray is large, the control means sets the lower limit position to the retreat position. When the number is small, the standby position is controlled as the retreat position.

In the second aspect of the present invention, in the configuration of the first aspect, the standby position detecting means is provided so as to be able to detect a sheet on the lower discharge tray, and the lower discharge tray is set to the lower limit. When the standby position detecting unit is in the position and the standby position detecting unit does not detect the sheet on the lower discharge tray, the control unit determines that the stacked amount of the sheet on the lower discharge tray is small. I am taking it.

According to a third aspect of the present invention, in the configuration of the first aspect, the standby position detecting means is provided so as to be able to detect a sheet on the lower discharge tray, and the lower discharge tray is connected to the lower limit. When the standby position detecting unit is in the non-detected state when the sheet on the lower discharge tray is removed while the control unit is in the position, the control unit loads the sheet on the lower discharge tray. It is configured to judge that the amount is small.

According to a fourth aspect of the present invention, in the configuration of the first, second or third aspect, the upper discharge tray has an end fence for aligning a rear end in a sheet discharge direction, and the height of the end fence is reduced. L1, L3 ≧ L1 where L2 is the overall height including the sheets when the lower discharge tray is full, and L3 is the lowering distance of the lower discharge tray from the standby position to the lower limit position. , L2 ≧ L1 + L3.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the standby position detecting means also serves as a full detecting means of the lower discharge tray.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic diagram of a finisher (sheet post-processing device) as a sheet stacking device. An entrance sensor SN1 and an entrance roller 4 are provided in the vicinity of a sheet transfer site J with a copying machine G as an image forming apparatus, and a sheet (including the concept of a sheet) taken in by the entrance roller 4 is provided. Depending on the processing mode, the sheet is discharged from the sheet discharge port E1 to a proof tray formed on the upper surface of the apparatus (clear mode), or is directly discharged from the sheet discharge port E2 as an upper discharge tray without performing a binding process.
(One in this embodiment) or discharged to the discharge tray 2 as a lower discharge tray capable of discharging a large amount of paper (shift mode), or through the sheet discharge port E2 through the binding process, or the discharge tray 1 or the discharged paper The sheet is discharged to the tray 2 (staple mode).

The transport route to the proof tray P is switched by a branching claw 21 provided downstream of the entrance roller 4, and the sheet is transported by the transport roller pair 5 a and discharged by the paper discharge roller pair 7. The branch claw 21 is driven by a solenoid 21a (FIG. 2), and when the solenoid 21a is turned off, the sheet is conveyed toward the proof tray P as shown by a solid line in FIG. In FIG. 1, reference numeral SN2 indicates a paper ejection sensor.

When the solenoid 21a is turned on and the branch claw 21 is at the position shown by the two-dot chain line, the sheet is guided to the horizontal conveying path. A branch claw 20 is provided downstream of the branch claw 21, and the sheet conveyed in the horizontal direction is selectively guided to a non-staple route B in which the binding process is not performed by the branch claw 20 or a staple route A in which the binding process is performed. Is done. The branch claw 20 is driven by a solenoid 20a (FIG. 2), and as shown in FIG.
Is turned on and comes to the position indicated by the two-dot chain line, the sheet is guided to the staple route A in a substantially vertical direction. FIG. 1 shows a state in which the solenoid 20a is turned off and guided to the non-staple route B.

In the non-staple route B, the sheet is conveyed by a pair of conveying rollers 5b, and is discharged to a discharge tray 1 or a discharge tray 2 by a pair of discharge rollers 8. Reference numeral SN4 denotes a paper discharge sensor, and reference numeral 85 denotes a paper discharge guide. The paper discharge tray 1 or the paper discharge tray 2 is individually driven by different drive sources, and the control unit 100 controls the position of the paper discharge tray E2 with respect to the sheet discharge port E2. This will be described later.
In the staple route A, the sheet is conveyed by the conveying roller pair 5c, sent to the staple unit 12, and subjected to a binding process. The bound sheets (bundle) are discharged to the discharge tray 1 or the discharge tray 2 by the discharge roller pair 8.
Reference numeral SN3 indicates a paper ejection sensor.

The discharge roller pair 8 is composed of a discharge roller 80 driven by a drive source (not shown) and a driven roller 82. The driven roller 82 is supported at its rear end in the sheet discharge direction and has a vertical direction. Is rotatably held at a free end side of a support member 84 which is rotatably provided. In the shift mode, the driven roller 82 is in pressure contact with the discharge roller 80 by its own weight. In the staple mode, the supporting member 84 is displaced upward to separate the sheet discharge roller 80 and the driven roller 82 from each other in order to avoid swelling at the rear end portion of the sheet bundle due to pressure contact, and the sheet in this state is displaced. A bundle release (described below) is performed. The trailing end of the sheet bundle is the discharge roller 8
When the value approaches 0, that is, when the possibility of swelling at the trailing end of the sheet bundle is eliminated, the support member 84 is returned to pinch the sheet bundle between the sheet discharging roller 80 and the driven roller 82 to discharge the sheet bundle. Has become. The return timing of the support member 84 is performed based on the detection information of the paper discharge sensor SN4.

Next, the operation when the staple mode is selected will be described. The sheet guided to the staple route A is conveyed by a conveying roller pair 5c, and a sheet discharging roller pair 6c.
Is discharged and stacked on a staple tray (not shown). In this case, alignment in the vertical direction (sheet conveyance direction) is performed by the hitting roller 9 for each sheet, and alignment in the horizontal direction (width direction) is performed by the jogger fence 11. Job breaks,
That is, the stapler S is driven by the staple signal from the control unit 100 between the last sheet of the sheet bundle and the leading sheet of the next sheet bundle, and the binding process is performed.
The sheet bundle on which the binding process has been performed is immediately sent to the discharge roller pair 8 by the discharge belt 10a having the discharge claw 10, and
The sheet is discharged onto the sheet discharge tray 1 or 2 corresponding to the sheet discharge port E2.

The hitting roller 9 is returned about the fulcrum 9a and is swung by a solenoid 9b (FIG. 2), and intermittently acts on the sheet discharged to the staple tray as shown in FIG. Hit 46. At this time, the backflow of the sheet rear end is prevented by the brush roller 6a forming one of the pair of paper discharge rollers 6. In addition, beating roller 9
Is rotating counterclockwise. Reference numeral SN8 denotes a home position detection sensor of the ejection claw 10.

When the shift mode is selected, the sheet is conveyed along the non-staple route B and directly discharged to the discharge tray 1 or 2. In response to a shift signal at a break between jobs (between the last sheet of the sheet group and the first sheet of the next sheet group), the discharge tray 1 or 2 is moved to the shift motor 88.
It is moved in the thrust direction (the sheet width direction orthogonal to the sheet discharge direction) by a drive mechanism (not shown) and a drive mechanism (not shown) to prepare for the next sheet group. By repeating this, the stacked state of the sheets is offset for each sheet group, and the sheets are separated.

Control means 1 as microcomputer
2 includes a CPU 102, an I / O interface 104, and the like, and signals from each switch (SW) of a control panel (not shown) of the apparatus main body and each sensor are transmitted to the I / O interface 104, as shown in FIG. Is input to the CPU 102 via the. Based on the input signal, the CPU 102 controls the vertical motor 50 for driving the discharge tray 1, the vertical motor 51 for driving the discharge tray 2, the shift motor 88, the solenoid 20 a, the solenoid 21 a,
The return solenoid 9b, the transport motor 52 for driving the transport roller pairs 5a, 5b, 5c, respectively, and the paper discharge roller pairs 7, 8
, A stapling motor 54 for driving the stapler S, a discharging motor 55 for driving the discharging belt 10a, a stapler moving motor 56 for moving the stapler S, a juger motor 57 for driving the jogger fence 11, and the like. . The pulse signal of the transport motor 52 that drives the transport roller pair 5c is
02 is input and counted, and the return solenoid 9b is controlled according to the count. In FIG. 2, DC
M indicates a DC motor, and STPM indicates a stepping motor.

As shown in FIG. 1, the retracted position of the discharge tray 1 is detected when the lower discharge tray 2 is made to correspond to the sheet discharge opening E2 of the apparatus body in order from the top. Position sensor SN5, a sheet surface detection sensor SN6 that is a positioning means for making the sheet discharge tray 1 or 2 correspond to the sheet discharge port E2, and can detect the upper surface of the stacked sheets, and a home position of the sheet discharge tray 2. A standby position detection sensor SN9 as standby position detection means for detecting a standby position as a function, and a lower limit position detection sensor as lower limit position detection means for detecting a lower limit position when a large amount of paper is discharged to the paper output tray 2. SN7 is provided. The detection signals of these sensors are input to the CPU 102 via the I / O interface 104.

A processing mode and a discharge tray are designated from an operation unit (not shown) of the image forming apparatus G or a computer connected to the image forming apparatus G. In this case, if the binding mode is selected in spite of the fact that the discharge destination is the proof tray P, the discharge destination has priority and the mode setting is released.

Next, a mechanism for raising and lowering the paper discharge trays 1 and 2 will be described. As shown in FIG. 3, the discharge tray 1 is
a, 39b attached to a base 40 fixed between them. A rotatable guide roller 44 is attached to the side plates 39a and 39b via a short axis (not shown), and the guide roller 44 has a U-shaped cross section of the guide rails 30a and 30b.
Are provided so as to be movable by being engaged with the inside. Since the guide rollers 44 are positioned by assembling the side plates 39a and 39b and the base 40, the guide rail 3
Detachment from 0a, 30b is prevented. A driving shaft 33a driven by a vertical motor 50;
To the timing belt 3 via the timing pulley 36
7 is hung with tension. A part of the side plates 39a and 39b is fixed to a part of the timing belt 37, and the unit including the sheet discharge tray 1 is suspended so as to be able to move up and down by this configuration.

The paper discharge tray 2 is, like the paper discharge tray 1,
It is attached to a base 43 fixed between the side plates 42a and 42b. A rotatable guide roller 44 is attached to the side plates 42a and 42b via a short axis (not shown), and the guide roller 44 has a U-shaped cross section of the guide rail 30.
a and 30b so as to be movable and engaged with the inside. The guide roller 44 includes the side plates 42a and 42b and the base 4
Since the positioning is performed by assembling with the guide rails 3, the guide rails 30 a and 30 b are prevented from coming off.
A timing belt 35 is tensioned around a drive shaft 41a driven by the vertical motor 51 and a driven shaft 41b via a timing pulley 34. A part of the side plates 42a and 42b is fixed to a part of the timing belt 35, and the unit including the sheet discharge tray 2 is suspended so as to be able to move up and down by this configuration.

The main part of the driving configuration of the paper discharge tray 2 will be described in detail with reference to FIGS. As shown in FIG. 4, the power generated by the vertical motor 51 is transmitted from the worm gear 58 to the worm wheel 70, the relay gear 72, and the gear 74 fixed to the drive shaft 41a. Because of the worm gear 58, the paper discharge tray 2 can be accurately held at a fixed position. Further, the safety configuration is adapted to cope with abnormal lowering of the discharge tray 2. In FIG. 4, the driven roller 82 is omitted.

As shown in FIG. 5, the worm wheel 70
Behind the worm wheel 70 is a coaxial gear 7
The worm wheel 70 is provided with a spring 78
, So as to mesh with the worm gear 58.
Although not shown, a concave portion and a convex portion are formed between the worm wheel 70 and the gear 76 so as to be meshable in the rotational direction and detachable in the axial direction. It is designed to rotate synchronously. Output tray 2
When the sheet is abnormally lowered or the sheet is loaded too much, the worm wheel 70 is displaced to the position shown by the two-dot chain line against the urging force of the spring 78 due to the separating action between the concave portion and the convex portion. The engagement with the wheel 70 is released, and the discharge tray 2 stops. Although not shown, the driving configuration of the discharge tray 1 is the same.

As shown in FIG. 6, the standby position detecting sensor SN9 is provided at the center of the sheet to be discharged in the sheet width direction, and has a rear end fence so that the rear end of the sheet in the sheet discharging direction comes into contact. It is provided so as to protrude from the surface of the side plate 32 serving as the base. More specifically, the standby position detection sensor SN9 is a filler type sensor (a sensor with an actuator), and the fixing member 60 of the apparatus main body.
And a movable piece 64 whose one end is pivotally supported by the fixed portion 62. Movable piece 6
A part of the sheet 4 projects from the side plate 32 in the sheet discharging direction, and is turned on / off by the upper and lower sides of the rear end of the sheet discharge tray 2 or the upper surface of the stacked sheets. The movable piece 64 is provided in the central portion of the discharged sheet, that is, in the range where the smallest size sheet stacked on the sheet discharge tray 2 passes, and can detect all size sheets. Evacuation position detection sensor SN
5. Paper surface detection sensor SN6, lower limit position detection sensor S
N7 has the same configuration and is similarly arranged. Note that a reflective optical sensor may be used as each of the above sensors.

As shown in FIG. 1, in the present embodiment, when the sheet is discharged from the sheet discharge port E2, the sheet trailing end does not remain inside the sheet discharge port E2. Is projected outward from the side plate 32,
In the retreating movement (upward movement) of the discharge tray 1 described later, the discharge tray 1 and the discharge rollers 80 interfere with each other. In order to avoid this, as shown in FIG. 7, a bent portion 31 is provided on each of the guide rails 30a and 30b. FIG. 7 shows that the sheet discharge tray 1 corresponds to the sheet discharge port E2,
This shows a state where the discharge tray 2 is retracted to the lower limit position. When the discharge tray 1 moves upward when the discharge tray 2 corresponds to the sheet discharge port E2, as shown in FIG. 8, the discharge tray 1 swings due to the displacement of the guide rollers 44, and thereby the discharge rollers Interference with 80 is avoided. The distance M1 between the guide rollers 44 in the discharge tray 1 is set to be longer than the length M of the bent portion 31. The swing of the discharge tray 1 changes the tension with the timing belt 37. In order to avoid this problem, as shown in FIG.
6 is fixed to the movable bracket 68 locked,
It can be displaced. FIG. 9 shows a state in which the sheet discharge tray 1 is retracted upward with the sheet discharge tray 2 corresponding to the sheet discharge port E2.

The discharge tray 1 performs an operation of retracting above the sheet discharge port E2, so that the stacked sheets do not return to the inside of the sheet discharge port E2 during the retracting movement so that the discharged sheets are discharged in the discharge direction. An end fence 1a for aligning and holding the ends is integrally formed. Thus, there is no need to provide a complicated shutter configuration at the sheet discharge port E2 to prevent the sheet from returning backward when passing through the sheet discharge port E2.

Next, the control operation of the discharge trays 1 and 2 by the control means 100 will be described. As shown in FIG. 10, the home positions (positions when the power is turned on) of the paper discharge trays 1 and 2 are the positions where the upper end of the end fence 1a of the paper discharge tray 1 is detected by the retreat position detection sensor SN5. The lower side of the tray 2 in the sheet discharging direction (hereinafter, simply referred to as the lower side) is a position where the standby position detection sensor SN9 detects the lower side. FIG. 11 and FIG. 12 show the positioning operation of the paper output trays 1 and 2 to the home position by the control means 100.
A description will be given based on the flowchart of FIG. Note that the discharge trays 1 and 2 may start moving at the same time.

When the power is turned on, the initial operation starts (S1), and the control means 100 checks on / off of the lower limit position detection sensor SN7 (S2). If it is off (not detected), it is determined that the paper discharge tray 2 is above the lower limit position, and the vertical motor 51 (hereinafter abbreviated) is driven to lower the paper discharge tray 2 (S3), and the standby position is detected. Check ON / OFF of the sensor SN9 (S4). When the standby position detection sensor SN9 is ON (detected), the paper discharge tray 2 is stopped (S5), and then raised (S5).
6). Subsequently, the standby position detection sensor SN9 is turned on.
It is checked off (S7), and when turned off, the paper discharge tray 2 is stopped (S8). As a result, the lower side of the discharge tray 2 is located at the standby position (the home position, which is a position detected by the standby position detection sensor SN9).

When the discharge tray 2 is at the lower limit position, that is, when the lower limit position detection sensor SN7 is ON in S2, the control means 100 raises the discharge tray 2 (S9), and the standby position detection sensor SN9. Is checked (S10), and when the standby position detection sensor SN9 is turned on (detection of the upper side of the paper discharge tray 2), the on / off of the standby position detection sensor SN9 is subsequently checked (S10).
11) When it is turned off, the discharge tray 2 is stopped (S1).
2). As a result, the lower side of the discharge tray 2 is located at the standby position.

When the discharge tray 2 is located between the lower limit position and the standby position, that is, in step S4, the standby position detection sensor SN9
Is off (not detected), the control means 100 checks on / off of the lower limit position detection sensor SN7 (S1).
3) When the switch is on, the discharge tray 2 is stopped (S1).
4) Then, it is raised (S15). Next, the on / off state of the standby position detection sensor SN9 is checked (S1).
6) If the standby position detection sensor SN9 is turned on (detection of the upper side of the paper discharge tray 2), then the on / off of the standby position detection sensor SN9 is checked (S17), and if it is turned off, the paper discharge tray 2 is stopped (S18). . This allows
The lower side of the discharge tray 2 is located at the standby position.

Next, the control means 100 checks on / off of the retreat position detecting sensor SN5 (S19), and when it is off (not detected), drives the vertical motor 50 (hereinafter abbreviated) to drive the paper discharge tray 1 Is raised (S20). Subsequently, the on / off state of the evacuation position detection sensor SN5 is checked (S21), and if it is on (the upper end of the end fence 1a is detected), the paper discharge tray 1 is stopped (S2).
2).

FIG. 13 shows a state in which the sheet discharge tray 1 is retracted and sheets are discharged to the sheet discharge tray 2. Sheet discharge port E2 for discharging sheets to the discharge tray 2
Is a position at which the upper surface of the discharge tray 2 or the upper surface of the stacked sheets is detected by the paper surface detection sensor SN6. FIG. 14 illustrates a state in which the sheet discharge tray 2 is retracted and sheets are discharged to the sheet discharge tray 1. In this case, since sheets are stacked on the discharge tray 2, the discharge tray 2 is retracted to the lower limit position from the viewpoint of preventing collision with the discharge tray 1.

In discharging sheets to the discharge tray 2 shown in FIG. 13, when the upper surface of the sheets stacked on the discharge tray 2 is detected by the paper surface detection sensor SN6, the discharge tray 2 is lowered by a predetermined distance. This operation is repeated when a large amount of paper is discharged. A large amount of paper is discharged to the paper discharge tray 2, and as shown in FIG. 15, the lower side of the paper discharge tray 2 is detected by the standby position detection sensor SN9, and the upper surface of the stacked sheets is detected by the paper surface detection sensor SN6. , The discharge tray 2 becomes full. When the discharge tray 2 becomes full, the detection of the fullness above the lower limit position is performed so that the sheet discharge destination can be switched to the discharge tray 1 without removing the sheets on the discharge tray 2. In this embodiment, the full position is also detected by the standby position detection sensor SN9. FIG.
6 indicates that when the paper output tray 2 becomes full,
Is retracted to the lower limit position, and the discharge tray 1 is moved to the sheet discharge port E.
2 shows a state corresponding to FIG.

The retreat amount of the paper discharge tray 2 in the full state must be an amount capable of making the paper discharge tray 1 correspond to the sheet discharge port E2 so as to be able to receive the sheet, and as shown in FIG. The amount of sheets that can be stacked on the tray 1 is determined by the height L1 of the end fence 1a. That is, by disposing the standby position detection sensor SN9 above the lower limit position detection sensor SN7 by a distance L3 (the descending distance from the standby position to the lower limit position) higher than the height L1 of the end fence 1a, the standby position detection sensor SN9 is provided.
9 is a sensor for detecting the fullness of the discharge tray 2 (fullness detecting means).
And the standby position detection sensor. However, the distance L2 from the paper surface detection sensor SN6 to the standby position detection sensor SN9 (the entire height including the sheet when the discharge tray 2 is full) needs to satisfy the condition of L2 ≧ L3.

The control operation when the sheet output to the paper output tray 1 is instructed while the paper output trays 1 and 2 are stopped at the home position will be described with reference to the flowcharts of FIGS. I do. The control means 100 lowers the sheet discharge tray 2 to retract (S1), and checks ON / OFF of the lower limit position detection sensor SN7 (S1).
2). When the lower limit position detection sensor SN7 is turned on (detected), the discharge tray 2 is stopped (S3), and the discharge tray 1 is lowered (S4). Next, the on / off state of the paper surface detection sensor SN6 is checked (S5), and the on / off state (the paper discharge tray 1) is checked.
After detecting the lower end of the paper surface sensor SN6
Is checked (S6), and when it is turned off, the sheet discharge tray 1 is stopped (S7).

Next, the on / off state of the standby position detection sensor SN9 is checked (S8), and if it is off, the control means 100 judges that the stacking amount of the sheets on the sheet discharge tray 2 is small, and retracts the standby position. The discharge tray 2 is raised to the position (S9). Next, the on / off state of the standby position detection sensor SN9 is checked (S10), and the on (off) of the paper discharge tray 2 is checked.
And then wait position detection sensor S
The on / off of N9 is checked (S11), and when it is turned off, the paper discharge tray 2 is stopped (S12). As a result, the lower side of the discharge tray 2 is located at the standby position. When the discharge tray 2 is designated as the next sheet discharge destination in such a state, the discharge tray 2 is moved from the standby position closer to the sheet discharge port E2 than the lower limit position, which is a basic retreat position, to the sheet discharge port E2. Because it moves to, the traveling time is short.

While the sheets are being discharged to the discharge tray 1, if the stacked amount of the sheets on the discharge tray 2 is small, the discharge tray 2 is raised and the lower side of the discharge tray 2 is detected by the standby position detecting sensor SN9. As shown in FIG. 19, the condition that the paper discharge tray 1 and the paper discharge tray 2 do not collide with each other even if the paper tray 1 is moved to a standby position (L3 ≧ L1, L2 ≧ L1 + L).
3, which is set to satisfy this condition in the present embodiment.

When the sheet output to the sheet discharge tray 1 is instructed and the sheets on the sheet discharge tray 2 are removed while the sheet discharge trays 1 and 2 are stopped at the home position, control is performed. The operation will be described with reference to the flowcharts of FIGS. The control means 100 is the paper discharge tray 2
Is lowered to retreat (S1), and ON / OFF of the lower limit position detection sensor SN7 is checked (S2). When the lower limit position detection sensor SN7 is turned on (detected), the discharge tray 2 is stopped (S3), and the discharge tray 1 is lowered (S4). Next, ON / OFF of the paper surface detection sensor SN6 is checked (S5), and when ON (detection of the lower end of the paper discharge tray 1), the ON / OFF of the paper surface detection sensor SN6 is subsequently performed.
It is checked off (S6), and when it is turned off, the discharge tray 1 is stopped (S7).

Next, the control means 100 checks ON / OFF of the standby position detecting sensor SN9 (S8). FIG.
As shown in FIG. 2, when the sheet on the discharge tray 2 is removed, the standby position detection sensor SN9 is turned off. When the standby position detection sensor SN9 is turned off, the control unit 100 determines that the stacking amount of the sheets on the paper output tray 2 is small, and raises the paper output tray 2 so that the standby position is set to the retracted position ( S9). Next, the on / off state of the standby position detection sensor SN9 is checked (S10). When the standby position detection sensor SN9 is turned on (upside detection of the paper discharge tray 2), the on / off state of the standby position detection sensor SN9 is subsequently checked (S1).
1) When turned off, the discharge tray 2 is stopped (S1).
2). As a result, as shown in FIG.
Is located at the standby position. When the discharge tray 2 is designated as the next sheet discharge destination in such a state, the discharge tray 2 is moved from the standby position closer to the sheet discharge port E2 than the lower limit position, which is a basic retreat position, to the sheet discharge port E2. Because it moves to, the traveling time is short.

In the above-described embodiment, the case in which the number of the discharge trays 1 is one is illustrated. Further, although the sheet stacking apparatus which is separate from the image forming apparatus is illustrated, the sheet stacking apparatus may be formed integrally with the image forming apparatus. Further, the determination of the amount of sheets on the discharge tray 2 may be performed based on a numerical value calculated from the sheet thickness and the number of discharged sheets.

[0046]

According to the first aspect of the present invention, when the stacking amount of sheets on the lower discharge tray is small, the standby position located above the lower limit position of the lower discharge tray is defined as the retreat position. Since the control is performed, the moving time of the lower discharge tray to the sheet discharge port can be shortened, and the speed can be increased.

According to the second aspect of the present invention, since the standby position detecting means determines the stacking amount of sheets on the lower discharge tray, the determination can be made easily and accurately.

According to the third aspect of the present invention, when the sheet on the lower discharge tray is removed and the standby position detecting means is in the non-detected state, it is determined that the stacked amount of the sheet is small. The standby position is set to the retracted position, so that the time required for the lower discharge tray to move to the sheet discharge port can be shortened.
Higher speed can be accommodated.

According to the fourth aspect of the invention, when the retracted position of the lower discharge tray is set to the standby position, it is possible to reliably prevent collision between the upper discharge tray and the lower discharge tray.

According to the fifth aspect of the present invention, since the standby position detecting means also functions as the full discharge tray detecting means,
The configuration can be simplified and the cost can be reduced as compared with the case where the components are separately provided.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a finisher as a sheet stacking apparatus according to an embodiment of the present invention.

FIG. 2 is a control block diagram.

FIG. 3 is a schematic side view of a vertical drive mechanism of a discharge tray.

FIG. 4 is a perspective view illustrating a vertical drive mechanism of a lower discharge tray.

FIG. 5 is a schematic plan view showing a safety configuration of a vertical drive mechanism of a lower discharge tray.

FIG. 6 is a schematic side view showing the configuration and operation of a standby position detecting means.

FIG. 7 is a schematic front view of a paper ejection tray up-down driving mechanism in a state where an upper paper ejection tray corresponds to a sheet ejection port and a lower paper ejection tray is retracted to a lower limit position.

FIG. 8 is a schematic front view showing a retreating operation of the upper discharge tray.

FIG. 9 is a schematic front view of a paper ejection tray up-down drive mechanism in a state where a lower ejection tray corresponds to a sheet ejection port and an upper ejection tray is retracted.

FIG. 10 is a schematic front view illustrating a home position of an upper discharge tray and a lower discharge tray.

FIG. 11 is a flowchart illustrating a control operation for positioning an upper sheet discharge tray and a lower sheet discharge tray at a home position.

FIG. 12 is a flowchart illustrating a control operation for positioning an upper sheet discharge tray and a lower sheet discharge tray at a home position.

FIG. 13 is a schematic front view showing a state in which the upper paper discharge tray is retracted and paper is discharged to the lower paper discharge tray.

FIG. 14 is a schematic front view illustrating a state in which the lower discharge tray is retracted to a lower limit position and discharges to the upper discharge tray.

FIG. 15 is a schematic front view showing a full state of a lower discharge tray.

FIG. 16 is a schematic front view showing a state in which the lower discharge tray in a full state is retracted to a lower limit position and discharges to the upper discharge tray.

FIG. 17 is a flowchart illustrating a control operation for retracting the lower sheet discharge tray to a standby position when the amount of stacked sheets is small.

FIG. 18 is a flowchart illustrating a control operation for retracting the lower sheet ejection tray to a standby position when the amount of stacked sheets is small.

FIG. 19 is a schematic front view of a state in which the lower discharge tray is retracted to a standby position when the amount of stacked sheets is small.

FIG. 20 is a flowchart illustrating a control operation for retracting the lower sheet ejection tray to a standby position when a sheet is removed.

FIG. 21 is a flowchart illustrating a control operation for retracting the lower sheet ejection tray to a standby position when a sheet is removed.

FIG. 22 is a schematic front view of a state in which a sheet on a lower discharge tray is removed.

FIG. 23 shows a state after removing a sheet on a lower sheet ejection tray.
FIG. 7 is a schematic front view of a state in which a lower discharge tray is retracted to a standby position.

[Explanation of symbols]

Reference Signs List 1 discharge tray as upper discharge tray 2 discharge tray as lower discharge tray 100 control means E2 sheet discharge port SN7 lower limit position detection sensor as lower limit position detection means SN9 standby position detection sensor as standby position detection means SN9 Standby position detection sensor as fullness detection means

Continuation of front page (72) Inventor Kenji Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 3F054 AA01 AC02 AC05 BA02 BD02 BF04 BF08 BF22 BH08 CA16 CA33

Claims (5)

[Claims] 1. A sheet having a sheet discharge port for discharging sheets, a plurality of discharge trays provided independently of each other so as to be vertically movable, and control means for individually associating these discharge trays with the sheet discharge ports. In the stacking device, the discharge tray may be an upper discharge tray that can retreat above the sheet discharge port, and a lower discharge sheet that retreats below the sheet discharge port when the upper discharge tray is used. A lower limit position when the lower discharge tray is used as a large-volume discharge tray is provided below the sheet discharge port, and a lower limit position detecting means for detecting the lower limit position is provided. A standby position as a home position of the lower discharge tray is provided between the sheet discharge port and the lower limit position, and a standby position detecting means for detecting the standby position. When a stack is provided and the stacking amount of sheets on the lower sheet ejection tray is large, the control means controls the lower limit position to be the retracted position, and when the stacked amount is small, the standby position is set to the retracted position. A sheet stacking device. 2. The sheet stacking device according to claim 1, wherein said standby position detecting means is provided so as to detect a sheet on said lower discharge tray, said lower discharge tray being at said lower limit position, and When the standby position detecting means does not detect a sheet on the lower discharge tray, the control means determines that the stacked amount of sheets on the lower discharge tray is small. . 3. The sheet stacking apparatus according to claim 1, wherein said standby position detecting means is provided so as to detect a sheet on said lower discharge tray, and said lower discharge tray is at said lower limit position. When the sheet on the lower discharge tray is removed and the standby position detecting means is in the non-detection state, the control means determines that the amount of stacked sheets on the lower discharge tray is small. A sheet stacking device characterized by determining. 4. The sheet stacking apparatus according to claim 1, wherein the upper discharge tray has an end fence for aligning the rear end of the sheet in the sheet discharge direction, and the height of the end fence is L.
1. When the overall height including the sheets when the lower discharge tray is full is L2, and when the lowering distance of the lower discharge tray from the standby position to the lower limit position is L3, L3
A sheet stacking device satisfying ≧ L1, L2 ≧ L1 + L3. 5. The sheet stacking apparatus according to claim 4, wherein said standby position detecting means also functions as a full detecting means for said lower discharge tray.