JPH10250892A - Sheet reversing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reverse and carry a sheet at high speed accompanying with fitting without motion of separation and pressure contact of a roller pair of a reversible carrier means and to eliminate a problem of generation of noise and lowering of longevity. SOLUTION: This sheet reversing device is constituted to adsorb and carry a sheet 1 by using an adsorbing carrier means 6 for a reversible carrier means for reversing carriage, to devise the adsorbing carrier means 6 to apply adsorbing carrying force only to the facing sheet 1 even in a carrying state where a following sheet to be carried in a main carrying passage 13 covers and rubs together with the preceding sheet 1 to be switch-back carried by the adsorbing carrier means 6 on the main carrying passage 13 and to make the sheet 1 easily slide when the other storing carrying force in the opposite direction works on the sheet 1 even when it faces against it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet reversing apparatus used in various sheet handling apparatuses such as a copying machine, a printer, and the like, for reversing and handling a conveyed sheet as necessary.

[0002]

2. Description of the Related Art FIG. 4 shows a sheet reversing device conventionally used in copying machines, printers and the like. This is configured as shown in FIG. 4A, and a pair of transport rollers a and b that are driven to rotate in one direction as shown in FIG.
After the sheet e is conveyed in the direction indicated by the arrow g along the main conveyance path f by the conveyance roller pairs c and d, the rear end of the sheet e is moved to the conveyance roller pair a, as shown in FIG. At a certain point in time until the sheet moves away from b and passes through the pair of conveying rollers c and d,
The sheet e is switched back in the direction indicated by the arrow h in FIG. 4D by the reverse rotation of the pair of conveying rollers c and d, and is fed into the switchback conveying path i branched from the main conveying path f. Like that.

Thus, for example, the sheet e having an image formed on the first surface is guided to the main transport path f, where it is switched back to the switchback transport path i to feed the front and back of the sheet e. The image can be inverted and used for the next image formation so that an image is formed on the second surface. Accordingly, copying and printing can be performed on both sides of the sheet e.

Further, with the recent increase in the speed of copiers and printers, it is required to increase the number of sheets e which are turned over per unit time by the sheet reversing device. To respond to this, conventionally, as shown in (e) and (f) of FIG. 4, the previous sheet e is not completely removed from the pair of transport rollers c and d in the main transport path f, and the next sheet e is Is introduced into the main transport path f, the transport timing of the next sheet e is advanced. For this reason, the rear end e1 of the preceding sheet e during switchback
Then, a double feeding state occurs in which the leading edge e2 of the next sheet e which is normally conveyed is rubbed and conveyed.

In order to stably and surely achieve the reverse conveyance of the rubbed sheet e, the rear end e1 of the preceding sheet e and the next sheet e at the portion of the conveying roller pair c and d.
Prior to the time point at which the leading edge e2 of the pair starts to rub, the transport roller c on the next sheet e side of the transport roller pair c, d is
As shown by broken lines in FIGS. 4E and 4F from the other transport roller d, the transport roller pair c and d are driven in reverse for switchback of the preceding sheet e. The introduction of the next sheet e into the main transport path f is not hindered, and the preceding sheet e is provided in the switchback transport path i earlier than the time when the transport roller c separates from the transport roller d. When the sheet reaches the pair of conveying rollers j and k, conveyance of the preceding sheet e through the switchback conveying path i is guaranteed.

When the preceding sheet e has come out of the pair of conveying rollers c and d as shown in FIG. 4G, the conveying roller c is again brought into pressure contact with the conveying roller d and both of them are driven to rotate in the forward direction. The sheet e can be reliably introduced into the main conveyance path f.

[0007]

However, in the above-described conventional sheet reversing device, the conveying roller pairs c and d are separated from each other or pressed against each other. Or in some places or in some cases. Further, there is also a problem that fatigue and abrasion occur due to repeated pressing and separation of the pair of conveying rollers c and d, thereby lowering the conveying force and lowering the durability.

In view of the above, an object of the present invention is to provide
It is an object of the present invention to provide a sheet reversing device in which a sheet can be switched back by a reversible conveying means that does not require pressure contact.

[0009]

In order to achieve the above object, a sheet reversing device according to the present invention comprises a first conveying means and a second conveying means.
After the sheet is conveyed in one direction along the main conveyance path by the conveyance means of the second conveyance means at a certain time until the rear end of the sheet separates from the first conveyance means and passes through the second conveyance means. In order to switch back the sheet by the reverse rotation and to feed the sheet to the switchback conveyance path branched from the main conveyance path, the second conveyance means suctions the sheet to the side of the main conveyance path where the switchback conveyance path is branched. A suction means for sucking and conveying the sheet by suctioning air with an exposed surface; a driving means for driving the suction and conveyance means by switching between forward and reverse; and a suction means for applying a suction force to the suction and conveyance means. It is assumed that.

In such a configuration, the suction conveyance unit is driven to rotate forward by the driving unit, and when the suction unit operates, cooperates with the first conveyance unit to convey the sheet in one direction along the main conveyance path. When the rotation is switched to the reverse rotation drive at a predetermined point in time before the sheet is detached from the first conveyance means and comes out of the suction conveyance means, the sheet introduced into the main conveyance path is switched back to the first conveyance means. In addition, the sheet can be fed and conveyed to a switchback conveyance path branched from the main conveyance path between the suction conveyance means.

[0011] Even if the next sheet is fed to the suction conveyance means at an early timing when the sheet to be switched back is not completely removed from the suction conveyance means, the suction conveyance function of the suction conveyance means which is driven in reverse rotation is not used. Works on the previous sheet in the switchback facing the suction surface, but the next sheet that is conveyed to the suction conveyance unit so as to rub on the previous sheet is blocked by the previous sheet. If the suction unit is driven in the reverse rotation state until the next sheet confronts the suction surface of the suction conveyance unit and sent to the conveyance unit in the switchback conveyance path, there is a problem with switchback conveyance of the previous sheet. Also, if the suction conveyance means is driven to rotate forward before the next sheet comes off the first conveyance means, the next sheet is surely sucked to a predetermined position on the main conveyance path. The sheet can be conveyed, and even if the previous sheet is facing the suction surface of the suction conveyance means at the time of switching to the normal rotation drive, the sheet is still adsorbed on the suction surface by the conveyance force of the conveyance means of the switchback conveyance path. It can slide easily and get out without difficulty.

In addition, while the conveyance of the preceding sheet and the next sheet is entrusted to the first conveying means and the conveying means of the switchback conveying path, only the function of the suction means is stopped.
By performing the same operation as separating the two conveyance units, the suction conveyance function of the suction conveyance unit can have no influence on the preceding sheet and the next sheet.

Therefore, the repetition of the separation and press-contact operations conventionally required for the second transporting means which is driven at high speed reversal conveyance in which the previous sheet and the next sheet rub against each other is driven by switching between forward and reverse for the reversal conveyance. Is unnecessary and does not generate noise.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a typical embodiment of the present invention will be described in detail with reference to FIGS.

In this embodiment, as shown in the first and second embodiments shown in FIGS. 1 (a) and 1 (b), the sheet 1 is switched back and forth to switch back. As the second conveying means to be used, a suction conveying means 6 using the suction belt 2 having the suction holes 2a is adopted. The suction belt 2 has a suction box 3 applied to the back as shown in FIGS. 1A and 1B, for example, and a fan 4 in the suction box 3.
By suctioning air as indicated by an arrow A by the suction means 5 composed of the following, a suction force is exerted on the suction surface 2b of the suction belt 2, and a suction conveyance function of suctioning and conveying the sheet 1 on the suction surface 2b is provided. It is designed to demonstrate.

However, the suction box 3 may be applied directly inside the portion forming the suction surface 2b of the suction belt 2, or instead of providing the fan 4 inside the suction box 3, the suction box 3 3 can be connected to an appropriate suction source, and the specific structure of the suction means 5 and the suction and conveyance means 6 should be designed variously on condition that the sheet 1 can be conveyed by suction on the surface to be the suction surface. Can be.

In the first embodiment shown in FIG. 1A, the suction belt 2 is stretched by a pair of rollers 15 and 16, and a pair of transport rollers 11 and 12 which is the first transport means of the present invention. The suction belt 2 is arranged so that the suction surface 2b is exposed only on the side of the switchback conveyance path 14 of the main conveyance path 13 provided with a pair of conveyance rollers 11 and 12 and the suction belt 2 The branching portion 17 of the switchback transport path 14 from the main transport path 13 is located between them.

In the second embodiment shown in FIG. 1B, the suction belt 2 is stretched by three rollers 15, 16, and 21, and the suction surface of the portion stretched by the rollers 15, 16 is provided. 2b extends along the main transport path 13 and the suction surface 2b of the portion stretched by the rollers 15 and 21 extends along the switchback transport path 14. Other configurations are the same as those of the first embodiment. In the second embodiment, the sheet 1 to be switched back and sent from the main transport path 13 to the switchback transport path 14
Since the suction surface 2b of the suction belt 2 can face and convey the sheet 1 even after entering the switchback conveyance path 14, the performance of feeding the sheet 1 into the switchback conveyance path 14 is the first embodiment. Better than in the example.

Each of the switchback transport paths 14 is provided with a pair of transport rollers 18 and 19 for transporting the sheet 1 sent from the branch 17 by switchback to the next.

Regardless of the conventional apparatus and the apparatus of the present invention, the sheet 1 conveyed along the main conveying path 13 in the direction of arrow B
Is switched back in the direction of arrow C by the second transport means and sent into the switchback transport path 14, without being caught at the branching portion 17 or backflowing to the main transport path 13,
In order to enable a smooth transition to the switchback transport path 14, a seal piece 121 made of a PET material or the like as shown in FIG. 2A is provided.

Conventionally, as shown in FIG. 2B, the seal piece 121 is a single piece, and the base is adhered to the transport path with a double-sided adhesive tape 22 or an adhesive. Since the deformation rigidity at the tip of such a seal piece 121 is low, the tip may be deformed, such as wavy, or may be easily deformed. If the leading end of the seal piece 121 partially floats inside the conveyance path due to these factors, the sheet 1 to be switched back is caught by the sheet and does not smoothly move to the switchback conveyance path 14, which hinders high-speed conveyance and causes a jam. Easy to invite the state.

In the present embodiment, in order to solve this problem, as in the first embodiment shown in FIG.
Is folded into two and attached by an adhesive 23 or the like, or is installed by omitting the attachment by the adhesive 23 or the like as in the second embodiment shown in FIG. 2D. Like that.

As a result, since the tip of the seal piece 121 is a folded part, the bending rigidity is improved, and the seal piece 121 is easily stabilized in a linear state, and is not easily deformed. In addition, the sheet 1 to be switched back can be smoothly transferred to the switchback conveyance path 14, and jamming caused by being caught in the branch portion 17 can be avoided.

In order to switch back and transport the sheet 1 using the suction / conveyance means 6, a reversible motor 31 for driving the suction belt 2 by switching between forward and reverse and a drive motor 32 for the fan 4 of the suction means 5 are provided. The operation is controlled by the control means 33. The control unit 33 can use an internal function of a microcomputer provided for controlling the operation of various sheet handling devices such as a copying machine and a printer equipped with the sheet reversing device of the present embodiment.
However, the present invention is not limited to this, and various dedicated control circuits and devices can be used.

The operation when the sheet 1 is reversely conveyed under the control of the control means 33 will be described with reference to FIG. The suction conveyance unit 6 is driven to rotate the suction belt 2 by a reversible motor 31 as an example of a driving unit thereof, and the fan 4 of the suction unit 5 is driven in one direction by a driving motor 32 as an example of the driving unit. The sheet 1 is conveyed in one direction indicated by an arrow B along the main conveyance path 13 as shown in FIG. 3A in cooperation with the conveying roller pairs 11 and 12 which are driven to rotate.

At a predetermined point in time when the sheet 1 is disengaged from the pair of conveying rollers 11 and 12 and comes off from the suction belt 2, preferably at a point immediately after the branching section 17 for high-speed conveyance,
As shown in FIG. 3B, the suction belt 2 is
1 is switched to the reverse drive. Thereby, the main transport path 1
3 is switched back by the suction belt 2. By this switchback, the sheet 1 is fed from the branching section 17 to the switchback transport path 14 as shown in FIG.

Here, for the high-speed reversal conveyance, at an early timing when the switchback of the previous sheet 1 is started,
The next sheet 1 is conveyed along the main conveyance path 13 toward the suction belt 2 as shown in FIGS. 3C and 3D. At this time, even if the next sheet 1 is put on the previous sheet 1 on the suction surface 2b of the suction belt 2 as shown by a virtual line in FIG. Power is next sheet 1
Therefore, neither the switchback conveyance of the previous sheet 1 by the suction belt 2 nor the conveyance of the next sheet 1 on the main conveyance path 13 by the conveyance roller pairs 11 and 12 does not interfere. Therefore, there is no need for operation control for separating them as in the case of the conventional conveyance by the conveyance roller pair.

As shown in FIG. 3D, the previous sheet 1 is transported by the pair of transport rollers 18 and 1 in the switchback transport path 14.
When the number reaches 9, the suction belt 2 is switched to the normal rotation drive by the reversible motor 31. At this time, even if the previous sheet 1 remains on the suction belt 2 as shown in FIGS. 3D and 3E, the suction belt 2 sucks the previous sheet 1 on the suction surface 2b and conveys it. In contrast, the transport roller pair 1
Reference numerals 8 and 19 are for holding the previous sheet 1 and conveying it, so that the previous sheet 1 can be conveyed to the suction surface 2b of the suction belt 2.
And can be reliably conveyed by an appropriate pinching force set on the conveying roller pairs 18 and 19 while sliding between them.
Further, in such a conveying state, as shown in FIG. 3E, the next sheet 1 rides over the previous sheet 1 still remaining on the suction surface 2b of the suction belt 2 and When the sheet reaches the suction surface 2b, it is sucked and sucked by the suction surface 2b and starts to be conveyed by the suction belt 2, and thereafter, even if the next sheet 1 comes off the conveyance roller pair 11, 12 of the main conveyance path 13, the suction is performed. The belt 2 reliably transports the sheet to the switchback position shown in FIG. Therefore, even in such a transport stage, there is no need for operation control for separating them as in the case of transport by a conventional transport roller pair.

By repeating the above-described transport operation, high-speed reverse transport can be continuously achieved at an early transport timing at which the next sheet 1 rubs against the preceding sheet 1, and forward / reverse switching is performed for the reverse transport. This eliminates the need for the repetition of the separation and press-contact operations conventionally required for the transporting means driven by moving, and thus does not generate noise. In addition, such a separation and press-contact of the rollers does not cause fatigue or deterioration in the performance of the transporting means, so that the service life can be extended.

Note that the transport state shown in FIG.
(E), the conveyance required for the preceding sheet 1 is achieved by the conveyance roller pairs 18 and 19 even if the suction of the suction belt 2 is stopped during conveyance in the conveyance state shown in FIG. Since the conveyance required for the next sheet 1 is also achieved by the conveyance roller pairs 11 and 12, the same operation and effect as in the case where the conveyance roller pair is separated as in the case of the conveyance by the conventional conveyance roller pair can be achieved. Is obtained.

[0031]

According to the present invention, instead of the reversing mechanism for the pair of reversible conveyance rollers, a suction conveyance means is used to drive the reversible conveyance rollers by switching between forward and reverse, or to control the suction and stop of the suction. In spite of the structure, it is possible to reliably achieve high-speed reversal conveyance without noise at the time of separating and pressing the rollers, and it is possible to avoid the problem of shortening the service life due to repeated separation and pressing of the rollers.

[Brief description of the drawings]

FIGS. 1A and 1B are configuration diagrams of an embodiment of the present invention, in which FIG. 1A shows a first embodiment and FIG. 1B shows a second embodiment.

FIGS. 2A and 2B show a branch portion between a main transport path and a switchback transport path in the embodiment of FIG. 1, wherein FIG. 2A is a general structure example, and FIG. 2B is a side view of a conventional seal piece; c),
(D) is two examples of the seal piece used in the present embodiment.

FIG. 3 illustrates a specific reverse conveyance of a sheet according to the exemplary embodiment illustrated using the first example of FIG.
It is an example of a state of five steps of (a)-(e).

FIG. 4 is an example of a state of seven stages (a) to (g) in reverse conveyance by a conventional sheet reversing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheet 2 Suction belt 2a Suction hole 2b Suction surface 5 Suction means (second conveyance means) 6 Suction conveyance means 11, 12 Transport roller pair (first conveyance means) 13 Main conveyance path 14 Switchback conveyance path 17 Branch 31 reversible motor (drive means) 33 control means

Claims (1)

[Claims] After a sheet is conveyed in one direction along a main conveyance path by a first conveyance means and a second conveyance means, a trailing end of the sheet is separated from the first conveyance means and the second conveyance means is provided. At a certain point in time until the vehicle exits,
In a sheet reversing device in which a sheet is switched back and fed into a switchback conveyance path branched from the main conveyance path, the second conveyance means includes a suction surface on a side of the main conveyance path where the switchback conveyance path is branched. A suction means for sucking and conveying the sheet by suction of air by exposing the suction means, a driving means for driving the suction and conveyance means by switching between forward and reverse, and a suction means for applying a suction force to the suction and conveyance means. Sheet reversing device.