JP2000109260A - Paper inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper inverter that can invert paper right inside the machine body so that it is perfected and can help reductions in size of paper processors. SOLUTION: One pair of inversion roller pairs 14-15 and 16-17 is installed for rotation in both directions. A paper uncurling part 20 is disposed at a place where two paper resupply shunts 19 meet on the output side of the inversion roller pairs 14-15 and 16-17. Paper 3 from a paper feed path 13 is wound about the inversion drive roller 14, before the inversion roller pair 14-15 is reversed in rotation to deliver the paper 3, which is not inverted or whose trailing edge in the winding step is now handled as the leading edge, to between a photosensitive member 6 and a transfer roller 7 again via the associated resupply shut 19, uncurling part 20, resupply path 21, and register roller pair 5-5. For perfecting sheets of paper 3 in succession, the first sheet paper is taken up by the inversion roller pair 14-15, and the second sheet paper is taken up by the other inversion roller pair 16-17 to which it is guided by a branch jaw 12 switching over the feed direction.

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 for performing double-sided processing on a sheet by using the sheet processing apparatus for performing processing such as printing on the sheet.

[0002]

2. Description of the Related Art In the above-described paper processing apparatus, it has become difficult to employ a conventionally known double-sided apparatus in accordance with a demand for downsizing of a machine. As in the two-sided printing device disclosed in Japanese Patent Application Laid-Open No. 193213/1995 and the paper reversing device disclosed in Japanese Patent Application Laid-Open No. 7-267461, the paper is reversed using a paper discharge unit to enable two-sided printing. A device has been proposed.

However, in the case of these conventional devices,
Since the paper is once discharged to the paper discharge unit, there is a problem that a paper jam or skew is likely to occur when the discharged paper is touched with a hand.

Accordingly, an object of the present invention is to provide a sheet reversing device capable of reversing a sheet without taking it out of the machine and enabling downsizing of a sheet processing apparatus.
Further, the present invention provides a sheet reversing device which can maintain a stable conveyance quality and image quality by suppressing a radius of curvature of a paper conveyance path and suppressing an increase in a curl amount depending on a paper type because of its small size. The purpose is to provide.

[0005]

According to a first aspect of the present invention, there is provided a sheet processing apparatus which performs a predetermined process in a sheet processing unit and conveys a sheet along a sheet conveying path in order to achieve the above object. In a sheet reversing device for reversing the fed sheet and re-supplying the sheet to the sheet processing section, and enabling the above-described processing on both sides of the sheet, a plurality of forward and reverse winding the sheets conveyed from the sheet processing section are performed. Rotatable winding means,
A sheet re-supply path to the sheet processing unit, and a forward and reverse rotation of the winding means so that the rear end side of the sheet in the transport direction from the sheet processing unit in the re-supply direction to the sheet processing unit. It is characterized by being inverted so as to be on the leading side.

According to a second aspect of the present invention, the plurality of paper winding means winds the paper in the same direction.

According to a third aspect of the present invention, the sheet re-supply path has a transport path for each of the plurality of sheet winding means.
At a position where the conveyance path merges upstream of the sheet processing unit in the sheet re-feeding direction, a curl removing unit for curling the sheet in a direction opposite to the sheet winding direction of the sheet winding unit is provided. It is characterized by the following.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic sectional view of an image forming apparatus as a sheet processing apparatus using an embodiment of a sheet reversing device according to the present invention, and FIG. 2 is an enlarged sectional view of a section of a sheet reversing unit. In the illustrated image forming apparatus, a sheet 3 loaded in a sheet cassette 2 in the apparatus main body 1 is transported by a sheet feed roller 4, a registration roller pair 5 aligns the image and the sheet, and An image is formed on the surface of the sheet 3 by the transfer roller 7, and then the sheet 3 is formed by the fixing roller pair 8.
Is melted and fixed on the surface.

When the image is not formed on both sides of the sheet 3, that is, when the image is not formed on both sides of the sheet 3, the sheet 3 is conveyed to the discharge roller pair 10 by the branching claw 9 and discharged onto the discharge tray 11, and the both sides of the sheet 3 are discharged. When forming an image on the
12, the sheet reversing drive roller 14 and the reversing driven roller 15 forming the first reversing roller pair constituting the sheet reversing device via the sheet transporting path 13;
The sheet 3 is conveyed to a reversing drive roller 16 and a reversing driven roller 17 forming a pair of reversing rollers.

[0010] A plurality of pressing members 18 for pressing the conveyed and wound paper 3 against the surface thereof are pressed against the large-diameter reversing drive rollers 14 and 16 of each of the pair of reversing rollers. Each reversing roller pair 14, 15
And resupply shunts 19, 19 for resupplying the paper 3 between the photoreceptor 6 and the transfer roller 7
Is provided at the merging position of the two re-supply shunts 19, 19,
A curl removing unit 20 for curling the paper 3 is provided, a resupply path 21 is connected downstream thereof, and a pair of transport rollers 22 is provided in the middle thereof. This resupply path 21
Are merged with the paper supply path from the manual feed tray 23.

A sensor 24 is provided near the branch claw 11 in the paper transport path 13, and a transport path toward the first pair of reversing rollers 14 and 15 on the downstream side of the branch claw 11 and the second sensor 24 are provided.
The branching members 25 and 26 made of a flexible material are provided in the transport path toward the pair of reversing rollers 16 and 17. Due to its flexibility, the branching member 25 bends while the sheet 3 is being conveyed to the pair of reversing rollers 14 and 15 so as not to prevent the sheet 3 from being carried between the pair of reversing rollers 14 and 15.

Next, the operation of this embodiment will be described. The leading end of the sheet 3 conveyed through the sheet conveying path 13 is a branch claw 1
The sheet 3 is guided by the pressing member 18 to the outer circumferential surface of the reversing drive roller 14 in a state where the sheet 3 is guided to the pair of reversing rollers 14 and 15 and the flexible branch member 25 is bent to allow the sheet 3 to pass. While being pressed, the reversing drive roller 14
It is wound up. And the trailing edge of paper 3 is sensor 2
4, after a preset time (time for the rear end of the sheet 3 to pass through the branching claw 12), the reversing roller pair 14
15 is reversed, and the paper 3 wound around the reversing drive roller 14 is moved to the paper transport path 13 with the rear end side at the time of loading as the leading side.
Returned to the direction. When the leading end of the returned sheet 3 hits the branching member 25, the conveying direction is changed by the branching member 25, and the sheet 3 enters the resupply shunt 18.

The paper 3 that has passed through the re-supply shunt 19 is curled by winding the sheet 3 around the reversing drive roller 14 while passing through the curl removing section 20. 5, is again supplied between the photoconductor 6 and the transfer roller 7, and is conveyed to the discharge roller pair 10 by the branching claw 9 after the image forming process on the back surface, and the discharge tray 1
It is discharged on 1.

When a plurality of sheets 3 are continuously processed on both sides, the first sheet 3 is wound by the first pair of reversing rollers 14 and 15, and then the second sheet 3 is separated by the branch pawl. 12, the transport direction is switched to the second reversing roller pair 16, 1
It is conveyed to 7 and wound up. The winding direction of the sheet 3 around the reversing drive roller 16 is the same as the winding direction of the reversing drive roller 14. At this time, the first pair of reversing rollers 14 and 15 rotate in reverse, and the first sheet 3
0 has been transported. Then, the second reversing roller pair 1
6 and 17 are also reversed, the paper 3 is returned toward the paper transport path 13 with the rear end side at the time of loading as the leading side, and the leading end of the returned paper 3 hits the branch member 25 to change the transport direction. Into the re-supply shunt 19 and the curl removing unit 2
Transport to 0. This operation is repeated to process a plurality of sheets 3 continuously.

[0015]

As described above, the sheet reversing device according to the first aspect only requires a plurality of mechanisms for winding the sheet once and reversing the traveling direction and returning the sheet to the sheet processing section. Since the installation space is small, the paper can be easily installed inside the paper processing apparatus, and there is an effect that double-sided processing of the paper can be performed without once taking the paper out of the apparatus.

According to the second aspect of the present invention, as described above, since the plurality of paper winding means wind the paper in the same direction, in addition to the above-mentioned common effects, stable transport quality and stable image quality can be obtained. There is an effect that can be realized.

According to a third aspect of the present invention, as described above, the sheet re-supply path is provided with the curl removing means for curling the sheet in a direction opposite to the sheet winding direction of the sheet winding means. Therefore, in addition to the above-mentioned common effects, there is an effect that the amount of curl of the sheet due to winding can be reduced, and more stable transport quality and image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall schematic sectional view of an image forming apparatus using an embodiment of a sheet reversing device according to the present invention.

FIG. 2 is an enlarged sectional view of one embodiment of a sheet reversing device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Paper feed cassette 3 Paper 4 Paper feed roller 5 Registration roller pair 6 Photoconductor 7 Transfer roller 8 Fixing roller pair 9 Branch claw 10 Paper discharge roller pair 11 Paper discharge tray 12 Branch claw 13 Paper transport path 14 Inversion drive roller (First reverse roller pair) 15 Reverse driven roller (first reverse roller pair) 16 Reverse drive roller (second reverse roller pair) 17 Reverse driven roller (second reverse roller pair) 18 Pressing member 19 Re Supply shunt 20 Curling section 21 Resupply path 22 Conveying roller pair 23 Manual feed roller 24 Sensor 25, 26 Branch member

Claims (3)

[Claims] 1. A sheet processing section which performs a predetermined process, reverses a sheet conveyed through a sheet conveying path, resupplies the sheet to the sheet processing section, and enables the above-described processing on both sides of the sheet. In the sheet reversing device, the sheet reversing device has a plurality of rewindable rewinding means for rewinding the sheet conveyed from the sheet processing unit, and a sheet resupply path to the sheet processing unit. A sheet reversing device for reversing the sheet so that the rear end of the sheet in the transport direction from the sheet processing unit is positioned at the head in the re-supply direction to the sheet processing unit by forward and reverse rotations. 2. The sheet reversing device according to claim 1, wherein said plurality of sheet winding means winds the sheet in the same direction. 3. The paper re-supply path has a transport path for each of the plurality of paper winding units, and the transport path is located at a position where the transport path merges upstream of the paper processing unit in a paper re-feeding direction. 3. The sheet reversing device according to claim 1, further comprising curling means for curling the sheet in a direction opposite to the sheet winding direction.