JP2003312902A - Paper reversing conveyor and image forming apparatus using the conveyor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce variations of horizontal registration and skew by making it possible to adjust the slack of a paper sheet when the sheet is clamped by jogger side fences. <P>SOLUTION: A fan 36 is provided beneath a transfer guide plate 13 and in a position below the jogger side fence 34 on a reference plane Rp past the center position of the paper sheet P. After the sheet P conveyed to a stacking part is clamped by the jogger side fences 34, the fan 36 sucks the sheet P from its underside to reduce the slack of the sheet P toward the fan 36 and move the slack to the opposite side. Under these conditions, the center of the sheet P is pressed with a roller 39. Even after the sheet has separated from the jogger side fences 34, the ends of the sheet are kept in alignment with the reference plane Rp and the slack near the reference plane Rp is adjusted to minimize variations of the position of each sheet end to enhance the accuracy of positioning the sheet P. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet reversing / conveying device used in an image forming apparatus such as a copying machine, a printer and a facsimile.

[0002]

2. Description of the Related Art FIG. 1 is a perspective view (A) and a conceptual side view (B) showing a conventional sheet inverting and conveying apparatus. In the example shown, the paper positioning method using the jogger side fence is executed.
In the figure, 10 is a reversing roller capable of normal and reverse rotation, 13 is a reversing conveyance guide plate, 34 is a jogger side fence, and 40 is a pressure roller.

In this apparatus, the sheets conveyed from the main body of the image forming apparatus (not shown) are temporarily stored in the stack portion, and the jogger side fence 34 is positioned corresponding to the sheet width of the sheet set (indicated by a two-dot chain line in the figure). As shown in FIG. 4), the sheet is positioned, the driving of the reversing roller 10 is switched to the conveying direction, and the pressure roller 40 is pressed to re-feed the sheet. It is a thing.

However, in this apparatus, as shown in FIG. 2, when there is a clearance cl between the jogger side fence 34 and the paper P, the variations in the lateral registration and skew become large. In order to reduce such a gap, it has conventionally been necessary to set the width of the jogger side fence 34 to be slightly smaller than the paper width in consideration of a decrease in the paper width due to heat shrinkage after fixing.

However, since the paper size and the parts precision of the jogger side fence 34 vary, the width of the jogger side fence 34 may be narrower than the intended paper width, which causes the jogger side fence 34 to become smaller.
There is a problem that the amount of deflection of the paper sandwiched between them changes, and the lateral resist and skew vary.

In view of the above-mentioned conventional problems, the present invention is
Provide a paper reversing / conveying device that can adjust the deflection near the reference surface of the jogger side fence when sandwiching the paper with the jogger side fence, and can perform paper positioning to reduce variations in lateral registration and skew. It is an object of the present invention to improve the accuracy of an image formed by a forming device.

[0007]

In order to achieve the above object, a sheet reversing and conveying apparatus according to a first aspect of the present invention comprises a jogger side fence for correcting the position of a sheet and a guide plate, and temporarily stores the sheet. In a sheet reversing / conveying device having a stacking section for carrying out, a fan is provided below the guide plate, and the fan is provided on the side of the jogger side fence serving as a reference from the center of the sheet so that the sheet can be sucked by the fan. Is characterized by.

According to a second aspect of the present invention, in order to achieve the above object, the sheet reversing / conveying device according to the first aspect is provided with a sheet thickness detecting means for discriminating the thickness of the sheet. It is characterized in that the suction force of the fan can be controlled.

According to a third aspect of the present invention, in order to achieve the above object, the sheet reversing / conveying device according to the first or second aspect is provided with a sheet type detecting means for discriminating the type of the sheet, and the above-mentioned method is used depending on the type of the sheet. It is characterized in that the suction force of the fan can be controlled.

According to a fourth aspect of the present invention, in order to achieve the above object, the sheet reversing and conveying device according to any one of the first to third aspects is provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. It should be noted that, in the following, the same parts as those in the prior art will be denoted by the same reference numerals, and overlapping description will be omitted. FIG. 3 is a conceptual sectional view of an image forming apparatus to which the present invention is applied. In the figure, 1 is an image forming device, 2 is a sheet reversing and discharging device, 3 is a reading device, 4 is a writing device, 8 is a paper feeding device, and 9 is a fixing device.

In this image forming apparatus, the writing device 4 forms a latent image on the photoconductor 6 of the image forming device 1 based on the image read by the reading device 3, and the latent image is formed by the developing device 7 of the image forming device 1. A visible image of the toner is created on the body 6. On the other hand, the paper P supplied from the paper feeding device 8 is conveyed to the image forming device 1 as indicated by an arrow 19 in the figure, the toner is transferred to the paper P by the image forming device 1, and the image is fixed by the fixing device 9. The paper P thus made is discharged to the paper discharge tray 11 or conveyed to the reversal discharge device 2.
When the paper P is discharged straight out of the image forming apparatus (normally), the paper discharge roller 20 is passed. The path for conveying the sheet to the reversal discharge device 2 is indicated by arrow 12 in the figure. A path for reversing the sheet P and discharging it to the outside of the apparatus is indicated by an arrow 14, and a path for reversing the sheet P in the reversing and discharging apparatus 2 and re-supplying it to the image forming apparatus 1 for forming images on both sides is shown in the figure. Shown by arrow 15.

FIG. 4 is an enlarged sectional view showing the reversal discharge device 2 in FIG. The paper P that has passed through the fixing device 9 is
Depending on the switching of the paper discharge branch claw 33, it is determined whether the paper passes through the paper discharge roller 20 or goes to the reverse discharge device 2. That is,
The paper P is conveyed to the reversal discharge device 2 by switching the discharge branch claw 33 in the direction shown by the solid line in the figure, and the straight discharge is performed by switching it in the direction shown by the broken line in the figure. When the discharge branch claw 33 is switched to the solid line direction,
Inverted entrance guide plate 2 via the path indicated by arrow 12
5a is provided with a detection sensor 26, which detects the trailing edge of the paper P in the traveling direction. Although not shown, the tip of the reversing branch claw 18 located below the conveying roller 17 provided beside the detection sensor 26 provided on the reversing inlet guide plate 25a is biased upward. A plurality of conveying rollers 17 and a plurality of reversing branch claws 18 are provided in the depth direction of the drawing. The tips of the reversing branch claws 18 are alternately inserted between the transport rollers 17,
When the sheet P enters between the conveying roller 17 and the reversing branch claw 18, the pressure of the reversing branch claw 18 causes the sheet P to be conveyed.
7, the reversing conveyance guide plate 13 is generated due to the conveyance force being exerted.
Is transported over.

FIG. 5 is an enlarged conceptual sectional view showing the first embodiment of the present invention applied to the stack portion 29 in FIG. In the drawing, 13 is a reverse conveyance guide plate, 34 is a jogger side fence, 36 is a fan, 39 is a roller, and a fan 36 is provided below the transfer guide plate 13. The fan 36 is provided below the jogger side fence 34 on the reference plane Rp side of the central position of the paper P.

The operation of this embodiment will be described. Fan 36
When the sheet P is re-fed as shown in FIG. 5 (A) in a state in which is not started, the central portion of the sheet P is pressed by the roller 39 as shown in FIG. When the sheet is separated from the fence, the sheet edge portion c does not follow the reference plane Rp as shown in FIG. In this state, a deviation d that causes variations in lateral registration and skew occurs. Therefore, as shown in FIG. 5D, after the sheets P conveyed to the stack portion are sandwiched by the jogger side fence 34, the fans 36 suck the sheets P from the lower surface side. Then, the slack of the paper P on the fan 36 side decreases,
The slack can be moved to the other side.

In this state, if the central portion of the paper P is pressed by the roller 39 as shown in FIG. 5 (E), even if the paper P is separated from the jogger side fence 34 as shown in FIG. Remains along the reference plane Rp. That is, the deflection of the jogger side fence 34 near the reference plane Rp is adjusted by sucking the paper P with the fan 36, and the positional accuracy of the paper P is improved by minimizing the variation in the position of the paper edge. .

FIG. 6 is an enlarged conceptual side view showing the second embodiment of the present invention similarly applied to the stack portion 29 in FIG. In the paper reversing / conveying device of this embodiment, the paper thickness detecting means 37 and the paper type detecting means 38 are arranged on the rollers 39. As the paper thickness detecting means 37 and the paper type detecting means 38, known ones may be appropriately adopted.

The width of the jogger side fence 34 is the paper P.
As described above, when the width of the paper P is narrower than that of the paper P, the amount of the flexure depends on the strength of the waist of the paper P. Since the waist of the paper P differs depending on the paper thickness and the paper type, the paper thickness and the paper type are detected by the paper thickness detecting means 37 and the paper type detecting means 38, and the suction force of the fan 36 is changed to change the paper. The deflected state of P is made constant so that the sheet position accuracy can be further improved. Although the illustration of the fan is omitted in FIG. 6, the configuration thereof is similar to that of FIG.

[0019]

As described above, the sheet reversing / conveying apparatus and the image forming apparatus using the same according to the present invention suck the sheet on the stack portion by the fan and remove the sheet near the reference surface of the stack portion. Since the deflection is adjusted, it is possible to reduce variations in lateral registration and skew as compared with the conventional paper reversing / conveying device that positions only with the jogger side fence, and it is possible to improve the stability of the paper position accuracy. There is an effect that the accuracy of the formed image can be improved.

In addition to the above-mentioned common effects, the sheet reversing and conveying apparatus and the image forming apparatus using the sheet reversing and conveying apparatus according to the second and third aspects, in addition to the above-mentioned common effects, This has the effect of reducing the influence of the thickness and type of the.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a conventional sheet reversing and conveying device.

FIG. 2 is a plan view showing a relationship between a jogger side fence and sheets in the apparatus shown in FIG.

FIG. 3 is a cross-sectional view showing an example of an image forming apparatus to which the present invention is applied.

FIG. 4 is an enlarged cross-sectional view of a reversal discharge device included in the image forming apparatus of FIG.

FIG. 5 is a front view showing the first embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

1 Imaging device 2 Inversion discharge device 3 reader 4 writing device 6 photoconductor 7 Developing device 8 Paper feeder 9 Fixing device 11 Output tray 13 Reverse conveyance guide plate 17 Conveyor roller 18 Inverted branch claw 20 Paper ejection roller 25a Reverse entrance guide plate 26 Detection sensor 29 Stack 33 Output branch claw 34 Jogger Side Fence 36 fans 37 Paper thickness detecting means 38 paper type detection means 39 Laura P paper Rp reference plane

Claims (4)

[Claims] 1. A sheet reversing / conveying device comprising a jogger side fence for correcting the position of a sheet and a guide plate, and a stack section for temporarily storing the sheet, wherein a fan is provided below the guide plate. A sheet reversing / conveying device, wherein the sheet is provided on the side of the jogger side fence that serves as a reference from the center of the sheet and the fan can suck the sheet. 2. The sheet inverting and conveying apparatus according to claim 1,
A sheet reversing / conveying device comprising a sheet thickness detecting means for determining the thickness of a sheet, and the suction force of the fan can be controlled by the thickness of the sheet. 3. The sheet reversing / conveying device according to claim 1, further comprising a sheet type detecting unit for discriminating the type of the sheet, wherein the suction force of the fan can be controlled according to the type of the sheet. Inversion transport device. 4. An image forming apparatus comprising the sheet reversing / conveying device according to claim 1.