JPS6261491B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves cutting out each page of continuous printing paper printed with a line printer to make a cut sheet,
This invention relates to a cut sheet stacking device that stacks cut sheets on a receiving table.

With the advent of laser beam electrophotographic line printers and the like, the speed of line printers has increased significantly in recent years, and with this, there has been a demand for higher speed post-processing devices for printed paper. Also,
From the viewpoint of labor saving, it has become necessary for post-processing devices to automatically cut sheets, and it has become a problem to stack the cut sheets reliably at high speed. Moreover, the printing paper used varies in size and weight, and it is necessary to stack all of these sheets reliably.

Many cutting sheet stacking methods have been proposed in the field of copying machines and post-processing devices, but there are many problems with high-speed stacking. It is necessary to stack sheets. In Figures 1 and 2,
This figure shows an example of a conventional stacking method.
FIGS. 3 to 8 show an example of a technical problem when trying to stack at the above-mentioned speed using the methods shown in FIGS. 1 and 2.

First, the conventional stacking operation will be explained with reference to FIGS. 1 and 2.

The cut sheets 1 are ejected by a feed roller 3 and an end roller 4, and are stacked so as to slide one after another onto a receiving table 5 at an inclined angle. A guide rack 8 is fixed above the stacked sheets 2 to prevent the sheets 1 from floating. When the sheets 2 are gradually piled up, the edge portion of the sheets 2 is detected by the optical sensor 9, and the receiving table 5 is lowered by a certain amount in the direction of arrow D by the lifting motor 13 via the lifting belt 14.
The gap H between the guide rack 8 and the upper surface of the sheet 2 is controlled to be approximately constant. sheet 2
is the front rack 7 provided on the sheet ejection side.
and a stop rack 6 provided on the anti-emission side. Front rack 7 is base 1
By moving the stop rack 6, which is fixed to the cutter 2 and attached to the movable rod 10, in the direction of the arrow L←→R, the front rack 7 and the stop rack 6 are opposed to each other at a position that matches the cut length l. Reference numeral 11 denotes a frame on which the end rollers 4, the guide rack 8, a sliding mechanism for the moving rod 10 (not shown), etc. are mounted.

When performing a high-speed stacking operation using the above-described stacking method, problems as shown in FIGS. 3 to 8 occur.

(1) Misalignment in the seat length direction (Figure 3) Distance W between stop rack 6 and front rack 7
is the distance obtained by adding the paper cut length l and the gap Δl. After the seat 1 collides with the stop rack 6, it rebounds in the direction of the arrow and moves toward the front rack 7, causing the end surface of the seat 2 to become irregular by an amount of Δl.

(2) Misalignment in the sheet width direction (Figure 4) Sheet 2 is aligned in the width direction B or F due to rebound.
This causes the sheet 2 to bend and become misaligned.

(3) Folding of the tip of the sheet (Fig. 5) Gap H between the guide rack 8 and the top surface of the sheet 2
If the value is not appropriate, a phenomenon occurs in which the leading edge of the sheet 2 is bent and bent. The range of H in which folding does not occur is very narrow, and when considering the degree of flatness of the upper surface of the sheet 2 and the amount of control of the gap H, it is difficult to maintain a constant range in this method.

(4) Rear-end collision of seats (Figure 6) A condition for high-speed stacking is to bring the leading seat 2 and the following seat 1 as close as possible. If the leading edge of the trailing sheet 1 is released while the trailing edge of the leading sheet 2 has not completed its fall, a rear-end collision will occur. The time interval between the leading edge and the trailing edge is required to be 30 mS or less, and this method
It is difficult to make it below mS.

(5) Overtaking stack (Figure 7) Sheets 2 should be stacked in page order, but the rear end of the leading sheet 2 may come into contact with the slope of the guide rack 8 due to the inertia of the sheet 2 or the static electricity of the guide rack 8. The falling is delayed, and a phenomenon occurs in which the succeeding sheet 1 gets under the leading sheet 2.

(6) Unable to stack (Fig. 8) If the setting of the gap H is inappropriate and the amount of stacking of the sheets 2 increases, the upper surface of the sheets 2 will curve, so that the guide rack 8 and the upper surface of the sheets 2 may partially overlap. If the gap h between the sheets 2 becomes smaller or they come into contact with each other, the sliding of the sheets 2 will be inhibited and stacking will become impossible.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a cut sheet stacking device capable of stacking cut sheets continuously at high speed.

In the present invention, when a sheet slides into a cradle, if there is a space above the sheet, the leading edge of the sheet may bend or the sheet may move and become misaligned, so it is necessary to always apply a constant light load onto the paper. Focusing on the fact that these problems can be solved by this method, the presser plate and stack height detection mechanism were devised so that a load is always applied even if the cut length of the sheet changes. Furthermore, in order to prevent the rear end of the sheet from colliding with the front end, the brush is used, and by focusing on the fact that the repulsion speed of the brush is high when the brush is released from the displaced state, the repulsion force causes the repulsion of the sheet. The sheet was devised so that the rear end would fall at a high speed, and the sheet itself would be stacked while being deflected, and the restoring force of this elasticity would be used to assist the sheet in falling at a high speed.

9 and 10 show the overall structure of a stacking device according to the present invention. Figures 9 and 10
The configuration and operation will be explained below using figures.

The cut sheet 1 is fed by the feed roller 3 from the direction of arrow A, and
The end roller 4 has a circumferential speed V _L that is approximately equal to the paper feeding speed, and the end brush 16 has a circumferential speed V _R that opposes the end roller 4 . The speed of the sheet 1 is required to be 50 inches/second to 100 inches/second. The stacking speed is determined by the cut length l of sheet 1.
Depending on the situation, the speed reaches about 10 sheets/sec to 3 sheets/sec, and the time interval between the trailing edge of the preceding sheet 2 and the leading edge of the succeeding sheet 1 is 30 ms or less. When the trailing edge of the preceding sheet 2 falls slowly, the leading edge of the trailing sheet 1 collides with it. The end brush 16 is provided to increase the falling speed of the rear end of the sheet 1, and its detailed operation will be described later with reference to FIGS. 23 and 24.

On the top surface of the sheet 2, there are several strip-shaped presser plates 1.
7 are placed so that they are in close contact with each other under their own weight. The appropriate weight of the presser plate 17 is 5 to 10 grams per piece.
It is preferable that the board be made of a material with high springiness and a thickness of about 0.1 mm. This presser plate 17 is supported by hooking one end to a fixing rod 18 and the other end to a hanger pin 20, and is devised so that only its own weight acts on the sheet 2 at all times, regardless of how much the sheets 2 are stacked. has been done. The detailed configuration of the holding plate 17 will be described later with reference to FIGS. 21 and 22.

The stacked sheets 2 are regulated by a front rack 7 fixed to a base 12 and a stop rack 6. The stop rack 6 is suspended from a movable rod 10, and the movable rod 10 can slide on the frame 11 in the L←→R direction to a position corresponding to the cut length l. A detection arm 22 is rotatably attached to an arm pin 24 fixed to the stop rack 6.
A roller pin 23 is fixed to the end of the detection arm 22, and a detection roller 19 is rotatably attached. These detection arms 2
2. The detection roller 19 is preferably as lightweight as possible, and is designed to always rotate counterclockwise around the arm pin 24 due to its center of gravity. Therefore, when sheet 2 exists, sheet 2
When the upper end of the arm 22 is lightly contacted and the sheet 2 is removed, the upper end of the arm 22 comes to rest against the arm stopper 26 attached to the moving rod 10. sheet 2
When the sheets 2 are stacked and their upper surfaces become higher, the arm 22 begins to rotate clockwise, and when it rotates by a certain angle, the non-contact switch 25 attached to the moving rod 10 is activated and the stack height of the sheets 2 is detected. , the pedestal 5 is lowered by a fixed amount in the direction of arrow D by the lifting motor 13 via the lifting belt 14. The amount of descent per time is approximately 5 mm. The details of the height detection and the raising and lowering operation of the pedestal will be described later with reference to FIGS. 11 to 14.

When the cut length l of the sheet 2 is short, by moving the moving rod 10 in the direction of the arrow L, the stop rack 6, the detection roller 19, the non-contact switch 25, etc. can be moved to the position indicated by the broken line.

Next, a specific example for solving the above technical problem will be described with reference to FIGS. 11 to 14. The technical problems addressed here are (1) misalignment in the sheet length direction, (2) misalignment in the sheet width direction, (3) folding of the leading edge of the sheet, and (6) inability to stack. The causes of problems (1) and (2) are that the frictional force that suppresses the movement is not acting on the sheet 2, and the cause of problem (3) is that the sheet 2
This is because there is a space on the top surface of the
The cause of (6) is that the frictional force becomes excessive. That is, the necessary conditions for solving these problems are as follows.

(a) Appropriate frictional force should be applied to the sheet 2 without leaving any space on the upper surface of the sheet 2. (b) The frictional force should not be excessive. (c) Even if the stack height of the sheet 2 changes, the frictional force remains constant. (d) Even if the upper surface of the sheet 2 is curved, the frictional force should not change much. (e) Even if the sheet cut length l changes, conditions (a) to (d) should be satisfied. It has been experimentally confirmed that the conditions are satisfied by the specific examples shown in FIGS. 11 to 14.

FIG. 11 shows the state at the start of the stack. Several rectangular pressing plates 17 are placed on the pedestal 5 so as to apply an appropriate frictional force to the sheet 2 and to avoid leaving any space, so as to be brought into close contact with each other by their own weight. Stop rack 6
A detection roller 19 is placed slightly inside by its own weight, and this detection roller 19 also has the purpose of applying a frictional force to the sheet 2. The configuration of the detection roller 19 is the ninth
This is as explained in FIGS.

By the detection arm 22, the non-contact switch 25
is in the ON state. The position of the upper surface of the pedestal 5 in this state is indicated by _UT . Subsequently, when stacking is started, the sheet 2 passes between the pedestal 5 and the holding plate 17 at high speed, slightly rotates the detection roller 19, and collides with the stop track 6.
If the weights of the presser plate 17 and the detection roller 19 are appropriate, the sheet 2 will not be misaligned due to rebound. Furthermore, the phenomenon of folding of the leading edge of the sheet 2 and the inability to stack the sheet 2 does not occur. It has been experimentally confirmed that even if the sheet cut length l changes, the weight remains constant. Each time the sheets 2 are stacked, the detection roller 19 floats up by the thickness of the sheets 2, and the detection arm 22 rotates clockwise little by little. Since the detection roller 19 itself also rotates, the impact force exerted by the sheet 2 on the detection arm 22 is alleviated, and the operation of the detection arm 22 is stable.

As the sheets 2 are stacked, the presser plate 17
is also lifted in the U direction. In order to keep the frictional force between the presser plate 17 and the sheet 2 constant, the presser plate 17 must always be free. That is, one end of the presser plate 17 must be rotatably supported around the fixed rod 18, and the other end must be freely supported so as to be movable in the left-right direction. This support structure is shown in FIG. That is, in FIG. 22, one end of the presser plate 17 is fixed to a rotating sleeve 27 that is rotatably fitted into the fixed rod 18, and the other end is provided with a square hole 17C, and a square hole 17C is provided in the other end, and a square hole 17C is formed in the hanger pin 20 press-fitted into the hanger rod 21. The hole 17C is designed to be hooked. In this way, the weight of the presser plate 17 can always be applied to the upper surface of the sheet 2 in a constant manner. Moreover, since several presser plates 17 are installed in the form of strips, each presser plate 17 acts independently on the curve of the sheet 2, so that there is almost no change in the frictional force against the curve.

In FIG. 12, when the sheets 2 are stacked by a height S, the detection arm 22 is activated by the non-contact switch 2.
5 is turned OFF, the pedestal 5 descends a certain amount and stops as shown in FIG. Seat 2 when stopped
The top surface of is approximately at the position of U _T shown in FIG.
As the pedestal 5 descends, the presser plate 17 also descends in the D direction while remaining in contact with the upper surface of the sheet 2, one end of which rotates clockwise and the other end moves to the left, keeping the frictional force constant. It can be done. Simultaneously with the descent, the detection roller 19 also returns counterclockwise due to the movement of its center of gravity, and the non-contact switch 25 is turned ON again. Next, stacking is started and the same operation is repeated. FIG. 14 shows the operation when stacking is completed. When stacking is completed, the tray 5 is lowered to the L _T position from which the paper 2 can be taken out. At this time, the holding plate 17 is supported at both ends by the fixing rod 18 and the hanger pin 20 and is bent by its own weight. and,
It is spaced apart from the top surface of the sheet 2 so as not to become an obstacle to taking out the sheet 2. On the other hand, the detection roller 19 is held with its rotation restricted by the arm stopper 26.

The above configuration and operation basically make it possible to stack cut sheets at high speed. However, when the cut length l is extremely short, for example when using 3.0 inch paper, a problem arises in that a space is created between the presser plate 17 and the sheet 2. FIGS. 15 to 17 show these problems and means for solving them.

Generally used cut length is maximum lmax = 14 inches, minimum lmin is 3.0 inches, between which 0.5
Often used in inch increments. FIG. 15 shows the cut length lmax lmin and the corresponding rack interval Wmax Wmin. Further, θ is the entry angle of the sheet 1. There is an appropriate range for the entry angle θ in which the leading edge of the sheet 1 can slide smoothly and the leading edge does not float up. Generally θ is 15~
It is set at about 17 degrees. As shown in FIG. 15, even at lmin, that is, when the stop rack 6 is set at the position indicated by the broken line, the holding plate 17 must apply a frictional force to the sheet 2. However, the presser plate 17
Because the deflection curve due to the rigidity, the mounting space, and the entry angle θ are constant, the presser plate 17
A problem arises in that it is difficult to bring the material into contact with the sheet 2.

FIG. 16 shows a solution to this problem. The main point of this means is that the detection roller 1
9. That is, in the state of Wmin, the detection roller 19 is arranged so as to be at the position indicated by the solid line. Specifically, as shown in FIG. 17, the center of the detection roller 19 is placed at a position K with respect to the stop rack 6. The value of K is approximately 2
~3 mm is preferred.

When K becomes large, the position is indicated by the broken line a shown in FIG.
9, and the sliding toward the pedestal 5 is inhibited. If K is too small, the height detection point will become the end face of the sheet 2, and the detected height will become unstable,
Frictional force no longer acts on the sheet 2 that enters, and misalignment occurs due to rebound.

In this way, in contrast to the optical sensor 9 shown in FIG. 1 used as a height detection means in the conventional device, the detection roller 19 according to the present invention is installed at the position K shown in FIG. By providing it at a position on the extension line of θ and near the contact point with the cradle 5, stable paper height detection can be obtained and the effect of frictional force on the sheet 2, especially the frictional force on lmin paper, can be prevented. A great effect can be obtained, and the problem with the presser plate 17 can be solved.

In FIG. 15, the distance over which the presser plate 17 acts is approximately Wmax-Wmin. Paper cut length l
The closer to lmin, the shorter the above action distance becomes.
Therefore, the frictional force also decreases, but the sheet cut length also shortens in proportion to this, so the inertia of the sheet also decreases, and the buckling strength in the longitudinal direction of the sheet increases, so even if the frictional force decreases, It has been confirmed through experiments that no curling or tip bending phenomena occur.

Next, since the presser plate 17 described so far has a rectangular shape, some inconvenience may occur when the width of the sheet 2 changes. This disadvantage and its solution will be explained with reference to FIGS. 18 to 21.

FIG. 18 shows an example of the arrangement of the presser plate 17 with respect to the sheet 2. As shown in FIG. W _H indicated the width of a certain sheet. When the sheet width to be used is W _h (W _H > W _h ) as shown in FIG. 19, that is, when the end surface of the presser plate 17 and the end surface of the sheet 2 almost match, the width shown in FIG. Arrow A as shown in
The sheet 2 released from the direction is slightly bent so that the sheet end surface 2a rides on the presser plate 17. If the pedestal 5 is lowered in this state, the sheet 2 will be caught on the presser plate 17, causing the sheets 2 to be misaligned and the presser plate 17 to be deformed.

In order to prevent this problem, in FIG. 21, slopes 17a and 17b are provided on the side surfaces of the presser plate 17 with respect to the traveling direction A of the sheet 2. As a result, even if the sheet 2 is slightly bent, the sheet 2 will not ride on the presser plate 17.

Next, a specific example will be described regarding problems with the conventional apparatus (4) rear-end collision of sheets and (5) overtaking stack.

As already mentioned, the time interval between the trailing edge of the preceding sheet 2 and the leading edge of the succeeding sheet 1 is required to be 30 ms or less. In the conventional apparatus, many methods have been proposed for dropping the rear end of the preceding sheet 2 onto the pedestal 5 at high speed, and a method using the end brush 16 shown in FIG. 23 is already known. However, in this case, as shown in FIG. 23, the falling speed of the rear end 2b due to the method of pulling down the rear end 2b of the sheet with the brush tip of the end brush 16 is the highest when there is no slip between the rear end 2b and the brush. becomes.
However, due to the inertia of the sheet 2, the rear end 2b temporarily separates from the outer circumference of the brush and then comes into contact with the outer circumference of the brush again, so the falling speed becomes unstable, and it is not possible to reduce the time t. Can not. In other words, it is becoming difficult to increase the speed.

FIG. 24 shows a specific embodiment to enable speeding up. Although not shown in the figure, in general, the shorter the cut sheet length, the greater the number of sheets stacked per unit time. That is, the value of t in FIG. 23 becomes smaller. For example, cut length
For 3.5-inch sheets, the stacking speed is 10 sheets/second, and one sheet must be stacked in 0.1 seconds.
In order to obtain this high speed, a method shown in FIG. 24 is provided.

The key point of this method is to give the brush tip of the end brush 16 a displacement of x with respect to the end roller 4, and to increase the falling speed of the rear end 2b by utilizing the repulsion speed of the brush tip. The guide plate 28 prevents the sheet 2 from flying freely while giving the sheet 2 a deflection and utilizing the release force of the deflection to shorten the falling time. The diagram of the end brush 16 shows the movement of one brush, and does not show the flocking density of the brush.

In the figure, the peripheral speed V _L of the end roller 4 and the peripheral speed V _B of the end brush 16 have a relationship of V _B ≧V _L , and the difference in peripheral speed is extremely small. The leading edge 1a of the sheet 1 is fed along the outer periphery of the end roller 4, and while contacting the guide plate 28 having a radius r, bites into the contact part f between the detection roller 19 and the pedestal 5, and then reaches the stop rack 6. Collide and come to rest. Rear end 2b at this time
is in the position shown in the figure, and the sheet 2 is in a curved state along the radius r. Continuing, when the displaced brush reaches point 16a→16b, the brush is released from the displaced state and reaches point 16c at high speed. The speed of the brush tip at this time is much greater than _VB . The rear end 2b of the sheet bites between the brushes due to the force released from the curvature of the sheet 2 and reliably falls from 2b to 2c depending on the repulsion speed of the brushes. Thereafter, the brush acts to press the sheet 2 onto the pedestal 5 at a speed of _VB . 29 is a static eliminating rod that uses corona discharge to remove static electricity from the guide plate 28, and the sheet 2 is attached to the guide plate 28.
This prevents it from being adsorbed.

According to this method, the trailing edge 2b of the sheet can be dropped reliably at high speed, making it possible to reduce the distance between the leading edge 1a and the trailing edge 2b, that is, the time interval, and achieve higher speed stacking compared to conventional devices. realizable. Although the case of Wmin is cited in FIG. 24, the operation is exactly the same in the case of Wmax.

In addition, the brush of the end brush 16 is made of a material that has little permanent deformation with respect to the displacement x, and since high rigidity is not required since the purpose is to drop the sheet, the brush diameter and length are appropriately selected to ensure wear resistance. Preferably.

For example, x=5 ₁ A brush with an outer diameter of 40 mm and 0.1 mm of nylon thread can be used.

According to the present invention, cut sheets can be stacked more quickly and reliably.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the general structure of the conventional device, Fig. 2 is a perspective view thereof, Figs. 3 to 8 are explanatory diagrams showing the drawbacks of the conventional device, and Fig. 9 is a perspective view of the device according to the present invention. 10 is a sectional view thereof, FIGS. 11 to 14 are sectional views showing the operation according to the present invention, FIGS. 15 to 17 are sectional views showing the arrangement of components according to the present invention, and FIG. 20 is an explanatory diagram showing the problem caused by the present invention, FIG. 21 is a plan view showing a solution to the problem, FIG. 22 is a perspective view showing details of some components according to the present invention, and FIG. FIG. 23 is an operational explanatory diagram showing the problem of the conventional device, and FIG. 24 is a sectional view showing a solution to the problem. In the figure, 6 is a stop rack, 10 is a moving bar,
16 is an end brush, 17 is a paper holding plate, 18 is a fixing rod, 19 is a detection roller, 20 is a hanger pin,
21 is a hanger rod, 22 is a detection arm, 23 is a roller pin, 24 is an arm pin, 26 is an arm stopper, 27 is a rotating sleeve, and 28 is a guide plate.

Claims (1)

[Scope of Claims] 1. A cut sheet stacking device configured to stack cut sheets discharged from a pair of feed rollers on a receiving tray provided diagonally below the feed rollers, the cut sheet stacking device having a front panel provided on the cut sheet discharge side. a stop rack provided on the opposite side of the cut sheet to be slidable along the length direction of the cut sheet; and a hanger extending in the width direction of the cut sheet and located on the outside of the opposite side of the stop rack. a fixed rod provided on the front rack side between the front rack and the stop rack; the ejection side end thereof is rotatably supported by the fixed rod, and the opposite end of the ejection side is rotatably supported by the hanger rod. a presser plate made of a strip-shaped thin plate having spring properties that is movably supported on the pedestal, always in close contact with the upper surface of the cut sheet on the pedestal, and extends along the length direction of the cut sheet, and the width of the presser plate is . A cut sheet stacking device characterized in that the cut sheet stacking device has a slope that becomes narrower toward the opposite end of the discharge side.