JP3246965B2 - Sheet transport path switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer path switching device for a branch provided in a sheet transfer path of an image forming apparatus such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, as a device for switching a sheet conveying direction at a branch portion of a sheet transport path, a switching claw for switching a position by a solenoid is conventionally provided at a branch portion. 2. Description of the Related Art A gate-type sheet conveyance path switching device that closes a conveyance path entrance different from a conveyance path and feeds a sheet to a selected path is widely used.

However, in the transport path switching apparatus of this type, if the switching claw is switched while the sheet is being transported to the branch portion, the sheet being transported is strongly sandwiched between the tip of the switching claw and the guide plate. In rare cases, a jam or damage to the sheet occurs, so that it is necessary to feed the sheet with a large sheet interval, which is not suitable for high-speed switching.

An air suction type paper switching apparatus which improves this point and enables high-speed switching is disclosed in Japanese Patent Application Laid-Open No. 60-524.
No. 55 discloses this. This apparatus provides suction ports on both sides of the conveyance path immediately upstream of the branching section, and when the sheet leading edge passes through this position, activates the suction port on the side of the selected path to move the sheet leading edge toward the sheet leading side. By pulling,
The sheet is guided to the selected route.

[0005] Although this system is capable of high-speed switching, it is not practical because the suction device has large disadvantages such as an increase in the size of the device, an increase in cost, and generation of noise.

[0006] In view of the above-mentioned problems of the gate system using the switching claw and the air suction system, the applicant of the present invention has proposed FIG.
(A) As shown in (b), a switching roller 1 capable of normal and reverse rotation is provided at a branch portion in parallel with a front end edge of a conveyed sheet, and a sheet 2 conveyed from a conveying roller pair 3 on the upstream side thereof. Of the sheet 2 is brought into contact with the peripheral surface of the switching roller 1 rotating in either direction, and the leading end of the sheet 2 is
Has proposed a sheet transport path switching device that selectively guides the sheet 2 to one transport path by the action force between the sheet and the peripheral surface of the sheet. In order to increase the acting force between the leading edge of the sheet and the peripheral surface of the switching roller, for example, it is preferable that the peripheral surface of the switching roller is planted with a brush to form a brush.

In FIG. 4A, when the switching roller 1 rotates counterclockwise as indicated by the solid line arrow, the sheet 4 whose leading end abuts the guide roller 4 is guided to the first transport path 4 as indicated by the solid line. When the switching roller 1 rotates clockwise as indicated by the dashed arrow, the sheet 2 whose leading end abuts the guide 2 is guided to the second transport path 5 as indicated by the dashed line.

Since the conveyance path is switched by switching the rotation direction of the switching roller 1, the switching operation can be performed irrespective of whether or not there is a sheet in the branch portion. High-speed switching. Further, since there is no suction operation of the solenoid, no sudden sound is generated and a low-cost and highly reliable switching device can be realized.

In this apparatus, the most ideal behavior is obtained when the sheet 2 conveyed by the conveying roller pair 3 advances straight toward the center of the switching roller 1, and the sheet 2 becomes stable without causing a jam or the like. The operation of switching the transport path is obtained.

However, actually, as shown in FIG.
The sheet 2 is curled while the sheet 2 is not curled. For example, the sheet that has passed through the fixing device is severely curled, particularly at the leading end.

As shown in FIG. 5, when the sheet is curled such that the leading edge of the sheet faces upward, when the sheet is switched to the lower second conveying path 5 by the switching roller 1, the sheet is conveyed by the conveying roller pair 3. Since the sheet 2 is curled upward, when it comes into contact with the rotating switching roller 1, it comes into contact with a portion above the roller center as shown in FIG.

Thereafter, the leading end of the sheet is guided downward by the clockwise rotation of the switching roller. During this time, the sheet 2 continues to be conveyed by the conveying roller pair 3, so that the sheet 2 loses its destination momentarily between the conveying roller pair 3 and the switching roller 1 as shown in FIG.

Further, the switching roller 1 rotates and guides the sheet 2 to the second conveying path 5. In this process, there is a moment when the curved portion of the sheet 2 is reversed as shown in FIG. . In (b), the sheet is curved with a concave upper surface, whereas in (c), the sheet is curved with a concave lower surface.

As described above, when the curled sheet is turned in the curl direction and the conveyance path is switched, there is a series of sheet movements described above.

When the bending direction is reversed, the switching roller 1 receives a greater load from the sheet 2. When the sheet is thick paper, the paper is subjected to a particularly large load because the paper is stiff. Slow down the rotation speed of roller 1,
When the conveying speed of the sheet 2 is increased, the switching roller 1
However, if the load is too large, the sheet 2 will buckle and a sheet jam will occur, or the sheet will move upward despite the rotation of the switching roller in the downward direction. I can't do it for sure.

Further, when the bending direction is reversed, a sudden noise is generated at the same time, which causes a problem that the noise is generated.

As a solution to prevent such a problem, a method of sufficiently increasing the rotation speed of the switching roller with respect to the sheet conveying speed is considered. However, the noise of a motor or the like provided for rotating the switching roller is large. Or it takes time to accelerate the roller to a predetermined rotation speed from a stopped state, which is not a good idea.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of a sheet conveying path switching apparatus using a switching roller previously proposed by the present applicant. It is an object of the present invention to provide a sheet conveyance path switching device which does not generate noise even when conveyed and can reliably switch the conveyance direction.

[0019]

SUMMARY OF THE INVENTION Two inventions for solving the above-mentioned problems are proposed here.

According to a first aspect of the present invention, in the sheet conveying path switching apparatus using the above-mentioned switching roller, the direction of the axis of the switching roller and the leading edge of the sheet obliquely intersect in a plane including the conveying surface. And

The second invention is characterized in that the switching roller is a pinch type roller.

[0022]

According to the former configuration, the front edge of the sheet conveyed by the pair of conveying rollers is firstly connected to the end of the switching roller provided obliquely near the front edge of the sheet. Make contact.

According to the latter configuration, the leading edge of the sheet abuts on the switching roller at both ends.

The sheet strain becomes weaker as the width becomes smaller and becomes stronger as the width becomes wider, even if the sheet has the same thickness. If you compare the force required to bend the entire width of the sheet by a fixed amount and the amount to bend only the corner of the sheet by a certain amount,
Much less force is required when bending corners. Therefore, when the front edge of the sheet abuts only at one or both ends of the switching roller as described above, the impact can be reduced as compared with the case where the entire front edge of the sheet abuts against the switching roller, and the sheet jam and the like can be reduced. A transfer path switching device without noise is obtained.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention. In the drawing, members having the same functions as those in FIG. 4 are denoted by the same reference numerals.

In the sheet conveying path switching device of the present embodiment, the central axis of the switching roller 1 is slightly within a plane including the front edge of the sheet 2 conveyed on the upstream conveying path of the branch portion and the sheet conveying surface. Are arranged so as to cross at an angle α. The other configuration and the transfer path switching operation are the same as those of the apparatus in FIG.

With this configuration, when the sheet 2 is conveyed, the right corner 2a of the front edge of the sheet 2 first comes into contact with the corresponding end of the switching roller 1. Of course, the inclination of the switching roller 1 with respect to the sheet leading edge may be reversed. In that case, the sheet comes into contact with the switching roller 1 from the left end of the front end of the sheet. This weakens the sheet,
The transfer path can be switched without a jam or noise.

In the case of this configuration, as shown in FIG. 2, only the vicinity of the end of the switching roller 1 at which the leading end of the conveyed sheet 2 first comes into contact is used to increase the acting force between the roller and the sheet. If a brush is installed, the part that comes into contact afterwards is guided in the direction that was directed by the brush that first contacted, so that even if there are no brushes in other parts, the sheet can be reliably switched to the desired transport path. Can help reduce costs.

In another embodiment shown in FIG. 3, the axis of the switching roller 1 is provided in parallel with the front edge of the sheet 2 to be conveyed, but the shape of the switching roller 1 is larger at both ends than at the center. It has a pinching shape that gradually increases.

Therefore, in this case, the sheet 2 abuts on the peripheral surface of the switching roller 1 at the both side ends 2a and 2c of the front end, and as in the embodiment of FIG. Can be prevented from occurring.

[0032]

As described above, according to the present invention, the impact at the time of abutment between the leading edge of the sheet and the peripheral surface of the switching roller is reduced, and a stable conveyance path switching without sheet jam due to impact noise or impact can be achieved. Can do it.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a plan view of another embodiment of the present invention.

FIG. 3 is a plan view of still another embodiment of the present invention.

FIGS. 4A and 4B are a side sectional view and a plan view of a sheet conveyance path switching device proposed above.

FIGS. 5 (a), (b), and (c) are FIGS.
FIG. 9 is an explanatory diagram illustrating a problem of the sheet conveyance path switching device illustrated in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Switching roller 2 Sheet 3 Transport roller 4 1st transport path 5 2nd transport path

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Tetsuo Yamanaka 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-3-95063 (JP, A) JP-A Sho 56-149058 (JP, A) JP-A-60-52455 (JP, A) JP-A-1-267230 (JP, A) JP-A 63-183157 (JP, U) JP-A 64-18059 (JP, A) U) Japanese Utility Model Hei 6-27795 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65H 29/60

Claims (3)

(57) [Claims] 1. A switching roller rotatable in both forward and reverse directions at a branch portion of a sheet conveying path, wherein a leading end of a sheet conveyed from an upstream side of the branch portion is switched to a switching roller rotating in either direction. In the sheet transport path switching device for abutting and switching the sheet transport path by the action force between the sheet leading edge and the switching roller peripheral surface, the axis of the switching roller and the sheet leading edge are within a plane including the transport surface. A sheet conveyance path switching device characterized by being oblique. 2. The switching roller according to claim 1, wherein an end of the switching roller which is closer to the edge of the sheet is provided with means for increasing the acting force between the edge of the sheet and the peripheral surface of the roller.
3. The sheet conveying path switching device according to claim 1. 3. A switching roller rotatable in both forward and reverse directions at a branch portion of a sheet transport path, and a leading end of a sheet conveyed from an upstream side of the branch portion is switched to a switching roller rotating in either direction. A sheet conveyance direction switching device for abutting and switching a sheet conveyance path by an acting force between a sheet front end and a peripheral surface of the switching roller, wherein the switching roller is a pinch type roller. Path switching device.