JP2001088985A - Printing medium matching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform the balance of degree of wear between both sides of a carrying roller. SOLUTION: A skew correction reference face part 32 is provided on one side of a carrying passage for a sheet 13. The skew correction reference face part 32 has a plurality of stair-like skew correction reference faces 28, and a passage, width limiting member 21 consisting of an elastically deformable sheet is provided above it. A carrying roller 20A is formed of a sphere. The sheet 13 advanced or skewed in the state closer to either lateral side relative to the carrying direction is matched and carried in the form where the sheet side surface is pressed to the skew correction reference faces 28 by the carrying roller 20A of a sheet matching mechanism part 24A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print medium aligning mechanism in an image forming apparatus.

[0002]

2. Description of the Related Art Image forming apparatuses are often used in general copying machines, and in recent years, color image forming apparatuses have become widespread. Hereinafter, an image forming apparatus capable of outputting a color image,
In particular, a latent image formed on the photoreceptor by a laser beam or the like is developed by a developing device of each color, and each color image formed on the photoreceptor is temporarily superimposed on an intermediate transfer body and held. A description will be given of a so-called intermediate transfer body type conventional image forming apparatus that collectively transfers a composite image to a sheet.

FIG. 1 is a configuration diagram of a conventional image forming apparatus. Reference numeral 1 denotes an image forming apparatus, and 2 denotes a laser unit, in which a laser oscillator, a polygon mirror, a lens, and the like are provided. Reference numeral 3 denotes a photoreceptor drum having a photoconductive layer on its surface, and a charger 14 for uniformly charging the photoreceptor and a developing device 4 for visualizing an electrostatic latent image are provided around the photoreceptor drum. ing. 5 is a developing roller, and 19 is a toner. Four developing devices 4 are provided corresponding to four colors of yellow, magenta, cyan, and black. 6
Denotes an intermediate transfer belt, which comes into contact with the photosensitive drum 3 by the action of the first transfer roller 7. Reference numeral 8 denotes a second transfer roller, which faces the intermediate transfer body belt 6. Reference numeral 15 denotes a cleaning member, and 9 denotes a fixing device.

[0004] A normal printing procedure of the image forming apparatus having the above configuration is as follows. The paper 13 is supplied from the paper supply cassette 10, and the paper 13 stops at the position where the end of the paper 13 is sandwiched by the registration rollers 16 for transporting the paper. The laser unit 2 emits light in accordance with the image signal to generate an electrostatic latent image on the photosensitive drum 3. First, development is performed by a yellow developing device 4 containing yellow toner. Next, the visible image on the photosensitive drum 3 is transferred to the intermediate transfer belt 6. This is magenta,
The same operation is performed for cyan and black, and images of each color are superimposed on the intermediate transfer belt 6.

Next, the sheet is sent from the registration roller 16 at a proper timing so that the image on the intermediate transfer belt 6 is formed at an appropriate position on the sheet. While the paper 13 passes through the second transfer roller 8, a transfer bias is applied to transfer the toner on the intermediate transfer belt 6 onto the paper 13 to form a visible image. When the sheet 13 passes through the fixing unit 9, the toner is heated by the heating roller of the fixing unit 9, the image is fixed on the sheet 13, and is discharged from the discharge port 133 of the image forming apparatus 1 to the top surface discharge tray 12. And printing is completed. The above is the operation in the single-sided printing mode.

On the other hand, recent image forming apparatuses have a high demand for double-sided printing, and many products have an optional double-sided printing apparatus. In an image forming apparatus having this double-sided printing device as an option, there is a transport direction reversing mechanism that can switch the transport direction of the paper, turn it over, and supply it again to the printing unit, instead of directly discharging the paper on which an image is formed on one side, It has a function to discharge paper after printing on both sides.

The double-sided printing mode will be described below with reference to the schematic configuration diagrams shown in FIGS. FIG. 5A is a plan view of a print medium alignment mechanism of a conventional image forming apparatus, and FIG.
Is a sectional view of the same. In one-sided image formation, the sheet 13 on which the image is fixed by the heating roller of the fixing device 9 is conveyed to the sheet discharge port 133 of the image forming apparatus 1 as in the one-sided printing mode. Until the lever 17 is passed, the operation is exactly the same as in the single-sided printing mode. Next, whether or not the sheet 13 has passed the lever 17 is determined by detecting the rear end of the sheet 13 with a photo interrupter. When the rear end of the paper 13 passes through the lever 17, the transport roller 1 in the paper discharge port 133 of the image forming apparatus 1
8 stops the rotation while holding the rear end of the sheet. Next, the lever 17 is at a rotational position for guiding the paper 13 nipped by the transport rollers 18 of the image forming apparatus 1 to the duplex printing device 22, and the transport rollers 18 rotate in a direction opposite to the direction in which the paper 13 is discharged to the top surface discharge tray 12. Then, the sheet 13 is drawn into the image forming apparatus 1 again, and is guided to a path extending to the duplex printing apparatus 22.

The paper 13 is transported in the duplex printing device 22 by transport rollers 20 and 21. The paper alignment mechanism 24 shown in FIG. 5 exists on this transport path. In FIG. 5, the transport roller 20 rotates with an inclination to the transport direction such that the paper 13 is corrected and moved to the reference side surface 23 in the width direction W. As a result, the paper 13 that has entered or skewed to the right or left with respect to the transport direction is aligned by the transport rollers 20 in the paper transport path by pressing the paper side against the reference side 23. It is conveyed while. Then, the sheet 13 is again conveyed to the registration roller 16, and the sheet 13 stops at a position where the sheet end is sandwiched between the registration rollers 16. Thereafter, in the same manner as the operation in the single-sided printing mode, the image is transferred and fixed on the back side of the paper 13, discharged from the discharge outlet 133 of the image forming apparatus 1 to the top-side discharge tray 12, and the double-sided printing is completed. I do. The above is the operation in the duplex printing mode.

[0009]

In the conventional image forming apparatus, the alignment is performed based on the same side regardless of the size of the sheet to be conveyed in the conveying path. The degree of wear of the conveying roller was different between the side surface and the opposite side, and as a result, troubles occurred in paper feeding.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a print medium aligning mechanism capable of equalizing the degree of wear on both sides of a transport roller.

[0011]

In order to achieve the above object, a print medium aligning mechanism according to the present invention includes a transport path for transporting a print medium, and transport means for transporting the print medium. Are provided with a plurality of skew correction reference planes on at least one side thereof.

With this configuration, an inexpensive print medium alignment mechanism that can make the balance of the degree of wear on both sides of the conveying means uniform can be realized.

[0013]

According to a first aspect of the present invention, there is provided a transport path for transporting a print medium, and a transport roller for transporting the print medium, wherein a plurality of transport rollers are provided on at least one side of the transport path. This is a print medium alignment mechanism provided with a skew correction reference plane.

According to a second aspect of the present invention, the plurality of skew feeding correction reference planes have a step shape.
It is a print medium alignment mechanism described in the above.

According to a third aspect of the present invention, there is provided the print medium aligning mechanism according to the first aspect, wherein the plurality of skew feeding correction reference surfaces have a groove shape.

According to the first to third aspects of the present invention, the skew correction reference position corresponding to each horizontal width of the print medium is changed by the plurality of skew correction reference planes, so that the center of the transport path or the vicinity of the center is printed. An inexpensive print-medium alignment mechanism can be realized in which the balance of the degree of abrasion on both sides of the conveying means is made uniform as a reference in the conveyance.

According to a fourth aspect of the present invention, a path width limiting member is provided above the plurality of skew feeding correction reference planes to limit a path width through which the print medium can be conveyed. 1 is a print medium alignment mechanism.

With this configuration, it is possible to prevent a malfunction due to the influence of the warping or bending of the printing medium, and to realize a stable alignment mechanism at the skew correction reference position corresponding to each width of the printing medium.

According to a fifth aspect of the present invention, there is provided the print medium alignment mechanism according to the first aspect, wherein the skew feeding correction reference surface is expanded outward on the paper feed port side.

With this configuration, the printing medium can be smoothly guided to the skew feeding correction reference position.

According to a sixth aspect of the present invention, there is provided the print medium alignment mechanism according to any one of the first to fifth aspects, wherein the transport roller is formed of a sphere or a spindle.

With this configuration, a frictional force against rotation of the print medium, movement in the path width direction, or movement in the transport direction can be reduced, and a smooth alignment mechanism can be realized.

According to a seventh aspect of the present invention, there is provided the print medium alignment mechanism according to any one of the first to sixth aspects, wherein the transport path is a transport path of a two-sided printing apparatus.

According to this configuration, the inventions of claims 1 to 6 are realized in the transport path of the duplex printing apparatus.

(Embodiment 1) FIG. 1 is a configuration diagram of an image forming apparatus according to Embodiment 1 of the present invention, FIG. 2A is a plan view of a print medium alignment mechanism of the image forming apparatus, and FIG. 3) is a cross-sectional view of a print medium alignment mechanism of the image forming apparatus. The configuration of the image forming apparatus shown in FIG. 1 is the same as that of the conventional example. In each drawing, the same reference numerals are given to the same elements as those described in the conventional technique, and the description thereof will be omitted.

In FIGS. 2A and 2B, a skew correction reference plane portion 32 is provided on one side of the transport path of the paper 13. The skew correction reference plane portion 32 has a step shape,
3 have a plurality of skew correction reference planes 28 in the width direction.
Above it, a path width limiting member 27 is provided. The path width limiting member 27 is made of an elastically deformable sheet, and limits the path width of the sheet 13 that can be conveyed.
As the path width limiting member, a member having a small coefficient of friction with paper is desirable, and a roller or the like can be used.

As shown in FIG. 2A, the skew correction reference plane 28 is gently bent outward and expanded at the paper feed port 26 side. The transport roller 20A is a sphere,
The rotation axis K is oblique to the transport direction of the sheet 13, thereby pressing the sheet 13 against the skew correction reference plane 28. Note that a spindle-shaped member or the like can also be applied as the transport roller.

Next, the operation will be described. In FIG. 1, the paper 13 that has been switched back at the paper output port 133 during the duplex printing mode is carried in from the paper feed port 25 of the duplex printing device 22. Thereafter, one skew feeding correction reference surface 28 corresponding to the width size of the paper 13 that is conveyed to the paper alignment mechanism 24A shown in FIG. . Then, the transport roller 20
A and 21 move in the F direction. At this time, the transport roller 20A is rotating so as to correct the paper 13 toward the skew correction reference plane 28 in the width direction W. As a result, the sheet 13 that has entered or skewed to the left or right with respect to the conveyance direction is pressed against the skew correction reference surface 28 by the conveyance roller 20A of the sheet alignment mechanism 24A. It is transported while being aligned in the form.
Here, since the transport roller 20A has a spherical shape,
The frictional force against the rotation of the sheet, the movement in the path width direction W or the movement in the transport direction F is reduced, and a smooth alignment mechanism can be performed. In this way, the sheet alignment mechanism 24A
Is passed through the paper discharge port 29 of the duplex printing device 22.
And is conveyed to the registration rollers 16 again.

(Embodiment 2) FIG. 3A is a plan view of a print medium alignment mechanism of an image forming apparatus according to Embodiment 2 of the present invention, and FIG. 3B is a sectional view of the same.

In the second embodiment, the skew feeding correction reference plane 3
Reference numerals 2 are provided on both sides of the transport path of the paper 13. In this configuration, the paper 13 that has been switched back at the paper output port 133 during the duplex printing mode is carried in from the paper feed port 25 of the duplex printing device 22. Thereafter, a set of skew correction reference planes 28 corresponding to the width of the paper 13 conveyed to the paper alignment mechanism 24B shown in FIG. You. Then, the paper 13 is transported by the transport roller 20A to the paper alignment mechanism 24B.
As the paper 1 moves in the F direction, the paper 1 that has entered or skewed or skewed to the right or left with respect to the transport direction
3 is conveyed while being aligned with the selected set of skew feeding correction reference planes 28 in a route-restricted manner. Here, since the transport roller 20A is a sphere, a frictional force against rotation of the paper 13 or movement in the width direction of the path is reduced, and a smooth alignment mechanism can be performed. In this manner, the sheet 13 that has passed through the sheet alignment mechanism 24B is discharged from the discharge port 29 of the duplex printing device 22, and is again
6.

(Embodiment 3) FIGS. 4 (a) and 4 (b)
FIG. 4A is a cross-sectional view of a print medium alignment mechanism of an image forming apparatus according to Embodiment 3 of the present invention, in which FIG. 4A shows a case where the skew correction reference plane portion 32 is on only one side, and FIG. It is.

A groove 33 is formed on the upper surface of the skew correction reference plane portion 32, and a skew correction reference plane 28 is formed. Therefore, this embodiment also has the same operation and effects as those of the first and second embodiments.

[0033]

As described above, according to the present invention, the reference at the time of transporting the print medium can be set at the center of the transport path or in the vicinity of the center at low cost without using a dedicated alignment motor for the print medium alignment mechanism. In addition, it is possible to eliminate the difference in the abrasion degree of the conveying roller between the reference side surface and the opposite side, which is concerned about the entire image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to a related art and a first embodiment of the present invention.

FIG. 2A is a plan view of a print medium aligning mechanism of the image forming apparatus according to the first embodiment of the present invention. FIG. 2B is a cross-sectional view of the print medium aligning mechanism of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3A is a plan view of a print medium aligning mechanism of the image forming apparatus according to the second embodiment of the present invention. FIG. 3B is a cross-sectional view of the print medium aligning mechanism of the image forming apparatus according to the second embodiment of the present invention.

4A is a cross-sectional view of a print medium alignment mechanism of an image forming apparatus according to Embodiment 3 of the present invention. FIG. 4B is a cross-sectional view of a print medium alignment mechanism of an image forming apparatus according to Embodiment 3 of the present invention.

5A is a plan view of a print medium alignment mechanism of a conventional image forming apparatus. FIG. 5B is a cross-sectional view of a print medium alignment mechanism of a conventional image forming apparatus.

[Explanation of symbols]

 13 Paper 20A Conveyance Rollers 24A, 24B Paper Alignment Mechanism 26 Paper Feed Port 27 Path Width Limiting Member 28 Skew Correction Reference Surface 33 Groove

Claims (7)

[Claims] 1. A transport path for transporting a print medium and a transport roller for transporting the print medium, wherein a plurality of skew correction reference planes are provided on at least one side of the transport path. Print media alignment mechanism. 2. The print medium alignment mechanism according to claim 1, wherein said plurality of skew correction reference planes have a stepped shape. 3. The print medium alignment mechanism according to claim 1, wherein said plurality of skew feeding correction reference surfaces are groove-shaped. 4. A print medium alignment mechanism according to claim 1, further comprising a path width limiting member provided above said plurality of skew correction reference planes, for limiting a path width of said print medium that can be transported. . 5. The print medium alignment mechanism according to claim 1, wherein the skew feeding correction reference surface is expanded outward on the paper feed port side. 6. A print medium alignment mechanism according to claim 1, wherein said transport roller is formed of a sphere or a spindle. 7. The print medium alignment mechanism according to claim 1, wherein said transport path is a transport path of a two-sided printing apparatus.