JP3167263B2 - Sheet material reversing device and image forming 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 sheet reversing apparatus for forming an image on both sides of a sheet material in a printer, a facsimile, a copying machine, and the like, and an image forming apparatus having the sheet reversing apparatus.

[0002]

2. Description of the Related Art Some image forming apparatuses such as printers, facsimile machines and copiers have a detachable sheet material reversing device mounted outside the image forming apparatus main body so that the sheet material can be reversed to form an image on both sides. There is a configuration of

FIG. 3 shows a configuration of a laser printer as a conventional example of such an image forming apparatus.

The laser printer 100 can form an image only on one side only with its own configuration (main body 101). However, as shown in the figure, a detachable sheet reversing device 102 is attached to the main body 101 as shown in FIG. Image formation can be performed on both sides.

[0005] In the laser printer 100, a video controller board (image signal generating means) 104 generates an image signal based on information transmitted from an external information device such as a personal computer or a word processor.

Here, various electronic components provided on the video controller board 104 are not shown.

The video controller board 4
The photosensitive drum 10 in which the laser scanner 105 is rotating clockwise with the laser beam L 'corresponding to the image signal created in
The electrostatic latent images are sequentially formed on the photosensitive drum 106A by irradiating the photosensitive drum 6A.

The electrostatic latent image formed on the photosensitive drum 106A is sequentially visualized by toner supplied from a developing unit (not shown) in the process unit 106, and is transferred to a transfer portion between the transfer roller 107 and the transfer roller 107. Transported to

On the other hand, the sheet material S 'stacked and stored in the sheet feeding cassette 108 is sequentially fed one by one from the uppermost sheet material by a half-moon shaped feeding roller 109 which makes one rotation in the counterclockwise direction. Sent to the conveyor roller pair 1
By 11, the sheet is conveyed to the registration roller pair 112 whose rotation is stopped.

After the sheet material S 'has reached the registration roller pair 112, the sheet material is continued to be conveyed until a predetermined loop is formed after the leading edge of the sheet material strikes the nip of the registration roller pair 112, and the skew state is corrected. You.

The sheet material S 'having been corrected for the skew state is
A pair of registration rollers 112 that starts rotating at the timing of aligning the position with the toner image on the photosensitive drum 106A
The toner image on the photosensitive drum 106 </ b> A is transferred onto the sheet surface by the transfer roller 7.

The sheet material S ', on which the transfer of the toner image is completed, is conveyed to the fixing roller 114 through the conveyance guide 113, where the transferred toner image is fixed on the sheet surface.

Sheet material S 'after fixing process of toner image
When the image forming apparatus 101 is selected for the one-sided image forming mode, the deflector 115 is switched to the position of 115A and the tray discharge path 11
6, the paper discharge tray 1 at the top of the image forming apparatus main body 103.
17 is discharged. At this time, the sheet material S ′ is transported by the transport roller pair 118 and is discharged by the discharge roller 119.

When the image forming apparatus 101 is set to the double-sided image forming mode, the deflector 115 removes the sheet material S ′ after the toner image fixing process.
By being switched to the position B, it is discharged to the outside of the main body 101 through the reverse connection path 120.

Sheet material S 'discharged out of main body 101
Is a deflector 122 in the sheet material reversing device main body 121.
Has been switched to the position of 122A, the transport roller pair 123, 1 has been moved to the switchback path 125A.
24.

The rear end of the sheet material S 'is a deflector 122A.
, The position is switched to the position of 122B, the conveying roller pair 124 rotates in the reverse direction, and is conveyed on the reversing path 125B by the conveying roller pairs 126 and 127. Transport roller pair 1
When the sheet material S 'is nipped at 27, the first surface of the sheet material S' on which the toner image has been transferred faces upward.

Next, the reference plate path 12 having the reference plate 128
9 is conveyed by a pair of oblique feed rollers 130 and 131 pressed against rollers by an inclined roller, and the position of the sheet material S ′ is corrected by aligning the sheet material S ′ with the reference plate 128. Is done.

Then, the registration roller pair 11 whose rotation is stopped again by the transport roller 132 in the re-feeding path 125C.
Conveyed to 2. Note that a passage 108A that forms a part of the refeed path 125C is formed in the sheet cassette 108.

After the sheet material S reaches the registration roller pair 112, the toner image is transferred to the second surface and fixed on the second surface in the same manner as in the case of the first surface. The paper is ejected upward.

[0020]

However, in the above conventional example, when the sheet material is reversed by the switchback path 125A and then conveyed by the conveying roller pair 124, it is attached when passing through the image forming means, especially the fixing roller 114. There is a disadvantage that the leading edge of the sheet is caught by the paper path due to the curl, causing a jam.

Further, a deflector 122 is required to prevent the leading end of the curled sheet from entering the conveying roller pair 123, which increases the number of parts and complicates the mechanism. was there.

The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to remove the curl of a curled sheet material, prevent jamming during conveyance, and simultaneously prevent jamming. An object of the present invention is to provide a highly reliable sheet material reversing device that can omit a configuration for the above purpose and an image forming apparatus provided with the sheet material reversing device.

[0023]

In order to achieve the above object, a sheet material reversing apparatus according to the present invention comprises a first sheet material reversing device.
A conveying path, and from the first sheet material conveying path via a branch portion.
Reverse the reverse transport path and the reverse transport path
And contacts the branch for transporting the inverted sheet material.
A second sheet material conveyance path to be continued and reverse conveyance of the branch portion
A transport roller for reciprocating the sheet material on the road side and this transport
Disposed opposite different predetermined positions in the circumferential direction of the roller
By at least two transport rollers
The sheet material is held at two predetermined holding positions, and the sheet material is
Curls the sheet material between the predetermined clamping positions
Forming a loop-shaped conveyance path for the first sheet
From the material transport path to the reverse transport path, and
Holds the sheet material at the holding position and moves forward from the reversal conveyance path.
A sheet conveying means for conveying the sheet to the second sheet material conveying path.
In addition, each of the holding positions is the second position from the reverse conveyance path.
The sheet material conveyed to the sheet material conveyance path is the second conveyance
It is characterized by being arranged to face the road side.

An image forming apparatus includes an image forming means for forming an image on a sheet material, and the sheet material reversing device described above, wherein the first material is provided at a discharge port of the sheet material discharged from the image forming means. A sheet material conveyance path is connected, and the inverted sheet material conveyed by the second sheet material conveyance path is supplied to the image forming unit.

[0025]

Embodiments of the present invention will be described below. Embodiment 1 FIG. 1 is an explanatory cross-sectional view for understanding the configuration of a laser printer as an image forming apparatus according to an embodiment of the present invention. 1 is a printer main body, 1a is stored in the lower part of the main body 1,
A sheet material cassette which is detachable and stores the sheet material S therein, 2 is a double-sided reversing unit mounted on the main body 1,
Reference numeral 2a denotes a reversing unit for reversing the sheet material S in the double-side reversing unit 2, and 2b denotes a transport unit for re-feeding the sheet material S to the main body 1 after the reversing unit 2a reverses the sheet material S. 3
Is a sheet material stored in the sheet material cassette 1a.

In the above configuration, the main body 1 is placed on the transport section 2b of the double-sided reversing unit 2.

Next, the conveying path of the sheet material will be described. Reference numerals 4a to 4e denote transport routes when paper is fed from the sheet material cassette 1a. The sheet material fed from the sheet material cassette 1a first passes through 4a. During this time, a series of processes necessary for image formation are performed in the same manner as described in the related art.

When an image is formed on one side only, the sheet material on which fixing has been completed enters the transport path 4b and is discharged onto a tray on the upper portion of the main body 1. In the case of double-sided printing, the sheet enters the transport path 4c as the first sheet transport path from the sheet outlet 1a of the main body 1.

The switching of the transport paths 4b and 4c is performed by a flapper 5 provided at the rear of the main body 1.

The sheet material entering the conveyance path 4c at the time of double-sided printing is conveyed to the reversing conveyance path 4e arranged on the cassette 1a via the branching section 8, and after stopping once, reverses and branches off from the branching section 8. The sheet enters a transport path 4d as a sheet transport path.

Reference numeral 16 denotes a flag provided in the transport path 4c for detecting the passage of the sheet material. The sensor 15 detects the timing at which the sheet material enters the branching section 8 and the rear end of the sheet material is transported from the transport path 4c. The drive control of the sandwiching / conveying means, which will be described later, is performed by detecting the timing of the operation.

The paper passing through the transport section 2b is re-fed to the main body 1 and again enters the path 4a. At this time, since the paper is turned upside down, the second side is printed, and when the printing is completed, the paper is discharged onto the tray on the upper portion of the main body 1 through the transport path 4b.

[0033] FIG. 2 shows a characteristic of the embodiment of the present implementation.

FIG. 2 shows the reverse conveying path 4 of the branching section 8 in FIG.
The pinching and conveying means 14 for conveying the sheet material 3 provided on the e side in a reciprocating manner will be described in detail. The nipping / conveying means 14 includes a conveying roller 14a driven by a driving means (not shown) and a pair of conveying rollers 14 which abut on different circumferential directions of the conveying roller 14a to pinch and convey the sheet material.
A roller assembly 18 composed of b and 14b is provided.

The sheet material S is placed on the outer guide 1 of the transport path 4c.
0, and passes between the transport roller 14a and the roller assembly 18, the sheet material S is pressed against the outer peripheral surface of the transport roller 14a as a loop-shaped transport path. Curled.

Since the direction of the curl at this time is opposite to the direction of the curl applied by the fixing device, the curl up to that point is removed.

The sheet material S has a transport roller 14 at its rear end.
a, and once stopped in a state of being sandwiched between the curl removing rollers 18, and is directed to the lower side, that is, the transport path 4 d side.

Thereafter, the conveying roller 14a rotates in the reverse direction, and the sheet material 3 is conveyed again in the reverse direction, and the curled sheet passes between the conveying roller 14a and the roller assembly 18, and
A second decurling is performed.

The rear end of the sheet material 3 has no curl,
Since it is directed downward by its own weight, when it re-passes through the branching section 8, it smoothly enters the transport path 4d and is transported without a deflector or a backflow prevention mylar at the branching section 8. As described above, since the curl-removing transport roller 14a and the roller assembly 18 are disposed at the branching portion 8 before the reversing transport path 4e, the curl is removed twice more, so that the curl can be removed more effectively .

[0040]

As described above, according to the sheet material reversing device of the present invention, the sheet material is reversed in the reversing conveyance path by the nipping and conveying means, and the curl applied in the upstream image forming step is curled. The curl is removed by bending the sheet material into a loop in the opposite direction.

Further, since the sheet material reciprocates by the holding and conveying means at the time of reversing and passes through the loop-shaped conveyance path twice, it is possible to effectively remove the curl.

By removing the curl of the sheet material, the sheet is smoothly passed without being caught in the branch portion or the sheet material conveying path, so that the occurrence of a jam due to the curl of the sheet can be prevented.

Further, when the sheet material is conveyed in the return direction from the reversing conveyance path, the sheet material does not flow backward to the first sheet material conveyance path, so that a guide member or a deflector for regulating the conveyance direction of the sheet material is unnecessary. , The number of parts is reduced, and the reliability of the device is improved.

[Brief description of the drawings]

FIG . 1 is an image forming apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating a configuration of a loading main body and a conveyance path of a sheet material.
You.

FIG. 2 is a diagram illustrating an embodiment of the present invention;
FIG. You.

FIG. 3 is a configuration of a main body and a transport path in the related art.
FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Printer main body, 1a Sheet material cassette 2 Double-sided reversing unit 2a Reversing unit 2b Transport unit 4a Transport path 4b Transport path 4c Transport path (first sheet material transport path) 4d Transport path (second sheet material transport path) 4e Inversion conveying path 5 flapper 8 bifurcation 10 outer guide 14 holding and conveying means 14a conveying roller 14b transport roller 18 Koroasshi Lee S sheet material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-236965 (JP, A) JP-A-2-13567 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 29/58 B65H 29/70

Claims (2)

(57) [Claims] And 1. A first sheet conveying path and connected via a branch portion from the first sheet conveying path
The reverse transport path and the sheet material that has been reversed by returning the reverse transport path in the opposite direction are transported.
Second sheet material transport connected to the branch for feeding
Path, and a sheet material for reciprocating the sheet material to the reversing conveyance path side of the branch portion.
The feed roller and a different predetermined circumferential direction of the transport roller
At least two transport rollers arranged opposite to the position
The sheet at at least two predetermined clamping positions
Of the predetermined holding position for holding the sheet material and holding the sheet material.
Form a loop-shaped transport path that curls the sheet material between them
And transports the sheet from the first sheet material transport path to the reverse transport path.
And then hold the sheet material at each of the above-mentioned holding positions.
Convey from the reverse conveyance path to the second sheet material conveyance path
And each of the holding positions is located between the reverse conveyance path and the second sheet.
The sheet material conveyed to the material conveyance path is on the second conveyance path side
Sheet reversal characterized by being arranged to face
apparatus. 2. An image forming means for forming an image on a sheet material.
And the sheet material reversing device according to claim 1.
An image forming apparatus, wherein
Sheet material transported by the first sheet material transport path
And the reverse of the sheet conveyed by the second sheet conveying path.
Supplying the sheet material to the image forming means.
Image forming apparatus.