JPH11165914A - Paper sheet transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet transfer device which avoids the occurrence of wrinkles in register roller set by eliminating unevenness even in the case where the unevenness occurs in flexure of the sheet at the time of resisting. SOLUTION: A paper sheet transfer device is provided with resist roller set 2, 3 and at least a pair of transfer rollers 5, 6. A leading end of the sheet is made to but against the nip of the resist roller set 2, 3 and flexed. Afterward, the resist roller set 2, 3 are rotated for a specified time. Then in the transfer roller set 5, 6 located on the upstream side of the resist roller set 2, 3, the driven roller 5 is relatively separated from the driving roller 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device used in an image forming apparatus such as a copying machine, a laser printer, a facsimile, etc., and more particularly to a registration roller pair for aligning a sheet with image information. It is.

[0002]

2. Description of the Related Art The alignment of image information to be copied or taken out by an image forming apparatus and a sheet to which the image information is to be transferred in the transport direction is generally performed as follows. That is, first, the sheet is fed to the nip portion of the registration roller pair in a stopped state by a group of transport roller pairs located on the upstream side thereof, and the leading end of the sheet is stopped at the nip portion, whereby the leading end position of the sheet is determined, At this time, the sheet is further bent by applying a further conveying force by the pair of conveying rollers on the upstream side. As a result, the entire front end of the sheet surely hits the nip portion, and the skew is corrected. Thereafter, the registration roller pair starts rotating at a predetermined timing, and the sheet is fed to the image transfer position and aligned.

[0003]

As described above, the pair of registration rollers is configured to bend the paper for skew correction. However, if the paper is skewed in the previous process, the above-described bending may be caused depending on the degree of the skew. During the formation, the paper may not be uniform in the width direction of the paper, and the magnitude of the bending may be different.
In addition, since the upstream conveying roller pair keeps holding the sheet, the state in which the deflection is distorted is maintained, and if the distortion is not corrected by a predetermined timing at which the registration roller pair starts to rotate, the state is changed. As it is, the sheet passes through the pair of registration rollers and is sent to the image transfer position, so that there is a problem in that an image is formed on the wrinkled sheet.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a paper transporting apparatus which eliminates unevenness even when unevenness occurs at the time of registration and prevents wrinkles from occurring at the registration roller pair. I do.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a paper transporting apparatus having a pair of registration rollers and at least one pair of transport rollers. This is solved by configuring the driven roller of the transport roller pair located on the upstream side of the registration roller pair to be relatively separated from the drive roller after a predetermined time after the rotation start of the registration roller pair. .

[0006] It is more preferable that the pair of conveying rollers is configured to be separated by rotation of the pair of registration rollers.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on examples shown in the drawings. In FIG. 1 showing a schematic configuration of a sheet conveying device according to the present invention, the conveying device includes registration roller pairs 2 and 3, conveying roller pairs 5 and 6, and a sheet conveying guide 8. The registration roller pair includes a registration driven roller 2 and a registration driving roller 3, and the conveyance roller pair includes a conveyance driven roller 5 and a conveyance driving roller 6. The sheet transport device further includes a sensor 10 for detecting the feeding of the sheet to the pair of registration rollers, just upstream of the pair of registration rollers. The paper transport device is disposed between the photoconductor 1 and the paper feed device 11.

As can be understood from FIG. 2, when the sheets are fed one by one from the sheet feeding section 11, the sheets are conveyed to the pair of registration rollers 2 and 3 by the pair of conveying rollers 5 and 6. At this time, the registration roller pairs 2 and 3 are stopped,
As a result, the leading edge of the sheet abuts on the nip portion of the pair of registration rollers to bend, and the sheet is aligned in the transport direction (FIG. 2B). At a predetermined timing, the pair of registration rollers 2 and 3 starts rotating, and feeds the sheet to the photoconductor, that is, the image transfer unit. At this time, the driven roller 5 of the transport rotor pair is separated from the drive roller 6 after the registration roller pair has rotated to the extent necessary to pinch the paper, and the paper restraint is released. As a result, the sheet is conveyed only by the pair of registration rollers 2 and 3. In order to separate the transport driven roller 5 from the transport driving roller 6, a conventionally known configuration, for example, a release means attached to the transport driven roller may be pulled by a solenoid or the like (not shown).

A structure for separating the conveying roller pairs 5 and 6 by the rotation of the registration driving roller 3 will be described below. FIG.
As can be understood from FIGS. 5 to 5, the registration driving roller 3 rotating in contact with the registration driven roller 2 is provided with bearings 13 and 14.
By the side plate 15. In particular, as shown in FIG. 4, a release drive lever 17 is disposed outside the bearing 13, and its inner sleeve portion is prevented from rotating by a pin or the like. As shown in FIG. 5, the release drive lever 17 has a built-in torque limiter 18.

On the other hand, the transport driven roller 5 has bearings 20 and 2.
1, both ends are pivotally supported by a release lever 22 and a support plate 23, respectively. The release lever 22 and the support plate 23 are fixed to a shaft 25 located on the side opposite to the registration drive roller with fixing screws or the like. The shaft 25 is supported on the side plate (15) by bearings 26 and 27. A tension spring 28 is provided between the conveyance driven roller 5 of the release lever 22 and the shaft 25, and the urging force causes the conveyance driven roller 5 to move the conveyance driving roller 6
(FIG. 3), and release lever 22 is released.
7 (FIGS. 3 and 4).

When the registration drive roller 3 starts to rotate in the direction indicated by the solid line arrow after the sheet abuts on the registration roller pair nip and bends, the release drive lever 17 is moved via the torque limiter 18 in the direction indicated by the arrow 27 in FIG. Rotate to
The release lever 22 is moved with the arrow 2 against the force of the tension spring 28.
Rotate in the direction of 8. The transport driven roller 5 is the shaft 2
5 rotates at the same time in the direction of arrow 28 with the fulcrum,
It is separated from the transport drive roller 6. When the release lever 22 collides with the stopper 30, the release drive lever 17 contacts the stopper 30 and stops by the action of the torque limiter 18 even if the registration drive roller 3 rotates.

When the pair of registration rollers 2 and 3 has conveyed the sheet, the registration drive roller 3 rotates in the direction of the dashed arrow.
That is, it reverses. The release drive lever 17 rotates in the direction of the arrow 29 until it comes into contact with the stopper 31. Along with this,
The release lever 22 is returned to the original position by the tensile force of the tension spring 28, and at the same time, the transport driven roller 5 is pressed against the transport drive roller 6.

[0013]

According to the present invention, after the leading edge of the sheet is brought into contact with the nip portion of the pair of registration rollers to bend, the rotation of the pair of registration rollers is started, and after a predetermined time, the conveyance located upstream of the pair of registration rollers. Since the driven roller of the roller pair is configured to be relatively separated from the drive roller, even when the resist deflection is not uniform, there is no restriction on the deflection, the unevenness of the deflection is eliminated, and the registration No wrinkles occur even when transported by a roller pair.

If the conveyance roller pair is separated by rotation of the registration roller pair, there is no need to provide a dedicated driving source for separating the conveyance roller pair, and the structure is relatively simple. The transport roller pair can be separated without taking up space.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a positional relationship among a sheet conveying device, a photoconductor, and a sheet feeding device according to the present invention.

FIGS. 2A and 2B are diagrams illustrating separation of a conveying roller pair in the sheet conveying apparatus according to the present invention, wherein FIG. 2A illustrates a state in which a sheet abuts a registration roller pair, FIG. () Shows when the pair of transport rollers is separated.

FIG. 3 is an end view showing a configuration in which a pair of conveyance rollers is separated by rotation of a registration roller.

FIG. 4 is a perspective view of a main part of the configuration corresponding to FIG. 3;

FIG. 5 is a partial view showing that a torque limiter is incorporated in a drive release lever.

[Explanation of symbols]

 2 Registration driven roller 3 Registration drive roller 5 Transport driven roller 6 Transport drive roller

Claims (2)

[Claims] An image forming apparatus comprising: a pair of registration rollers; and at least one pair of conveyance rollers, wherein the pair of registration rollers is rotated by a predetermined time after the leading edge of a sheet is pressed against a nip portion of the pair of registration rollers, and the registration roller is rotated. A sheet transport device, wherein a driven roller of a transport roller pair located upstream of the pair is configured to be relatively separated from a drive roller. 2. The sheet conveying apparatus according to claim 1, wherein the pair of conveying rollers is separated from each other by rotation of the pair of registration rollers.