JPH01187144A - Original document transport apparatus - Google Patents

Abstract

PURPOSE:To obtain a copy image of uniform lateral magnification by providing an idler roller below a drive roller, and disposing original (document) support rolls having the substantially same diameter as that of the idler roll on the rotary shaft of the idler roller at designated spaces not to contact drive rolls. CONSTITUTION:A driver roller 20 comprises a plurality of drive rolls 21 mounted on a rotating shaft. An idler roller 22 positioned below the drive roller 20 comprises a plurality of idler rolls 23 mounted on a rotating shaft. Original document support rolls 24 having the substantially same diameter as that of the idler roll 3 and a width a little larger than that of the idler roll are mounted at designated spaces not to contact the drive rolls 21 on the same rotating shaft of the idler roller 22. Accordingly, even if the original document is pushed upward by the idler rolls 23, portions of the original document that are not pushed by the idler rolls 23 are lifted up for the same amount by the original document support rolls 24, so that the slackening of the original document can be prevented so as to obtain a copy image of uniform lateral magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a document conveying device for reading a document image and transferring it onto recording paper while conveying the document itself.

[Conventional technology]

2. Description of the Related Art Conventionally, image forming apparatuses that copy large-sized original images, such as A1 size documents, are configured to read the original image while transporting the original itself, and form a copied image on recording paper.

FIG. 2 is a sectional view showing the structure of a document conveyance device in such an image forming apparatus, and an optical unit 2 for reading a document image is disposed in the middle of the document conveyance path 1. As shown in FIG. Further, a white platen roller 4 is disposed opposite the platen glass 3 on the image reading surface of the optical unit 2. Further, drive rollers 6.7 and eye rollers 8 to 11 are arranged on the upstream and downstream sides of the optical unit 2, and the originals fed by the drive rollers 12 and idler rollers 13 at the entrance of the original transport path 1 are placed on the upstream side. The document is conveyed between the platen glass 3 and the white platen roller 4 by a drive roller 6 and an idler roller 8, and the image of the document is read by the optical unit 2 during the conveyance. The document that has passed through the reading surface of the optical unit 2 is conveyed to the exit of the document conveyance path 1 by the drive loaf and idler roller 10 on the downstream side. In this case, the drive roller 6.7°12.3
On the downstream side of 9.37, there are claws 15.16. for switching the conveyance route.
51, 52, and 53 are provided, and when the claw 15 is switched opposite to the illustrated state, the original that has passed the reading surface of the optical unit 2 passes between the drive roller 42 and the original, such as a thick original or The document is discharged toward the rear discharge port 43 for long documents.

However, if the document is a thin document of AO size to A4 size, the claw 15 is switched to the state shown in the drawing.

And A3. When copying multiple A4 size originals,
The claw 16 is switched to the opposite state from the one shown, and the document that has been read by the optical unit 2 passes between the drive roller 7 and the idler roller 11 and between the drive blow 6 and the idler roller 9, and then passes between the drive roller 6 and the idler roller 9 again. It is conveyed to the reading surface of the optical unit 2 by the idler roller 8 .

When the set number of copies are completed by such repeated conveyance, the claw 16 is switched to the state shown in the figure, and the document is transferred to the drive roller 12 .
39, 37, 35, and 47 to the front outlet 50.

In the case of an A2 size document, the pawl 51 is switched in place of the pawl 16 in the same way, so that after the document has circulated between the drive roller 7 and the drive roller 12 for a number of openings equivalent to the number of copies, the drive roller 39°37 .35.47 and is discharged to the front discharge port 50. In the case of an A1 size original, the pawl 52 is switched in the same way, so that after the original has circulated between the drive roller 57 and the drive roller 39 for a number of openings equivalent to the number of copies, the drive roller 37.35°47
is discharged through the front discharge port 50.

Furthermore, in the case of an AO size document, the pawl 53 is switched in the same manner, so that the document circulates between the drive rows 57 and 537 for a number of copies equivalent to the number of copies, and then passes through the drive rollers 35 and 47 and forwards. It is discharged to the discharge port 50.

In this way, the conveyance path is switched depending on the document size.

[Problem to be solved by the invention]

However, in the above-described document conveyance device, in a conveyance region where the idler roller is below the drive roller, that is, for example, in a conveyance region where the drive roller 6 and the idler roller 8, and the drive roller 12 and the idler roller 13 are located, the idler roller is located below the drive roller. Since the document itself is pressed toward the drive roller by the rollers 8.13, if the document size is large, the document itself will sag between the O-roll and the roll in the width direction. That is, when the document is viewed in cross section in the width direction, sagging occurs where the contact portion between the drive roller and the idler roller becomes a peak and the non-contact portion becomes a trough. This slack accumulates until it reaches the optical unit.

For this reason, the horizontal magnification of the original image read by the optical unit 2 differs between the leading edge and the trailing edge of the original, resulting in a problem that a copied image with uniform horizontal magnification cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a document conveying device that can print a copy image with uniform horizontal magnification.

[Means to solve the problem]

In the present invention, document support rolls having approximately the same diameter as the idler roll are arranged at predetermined intervals on the rotation axis of the idler roller which is located below the drive roller so as not to come into contact with the drive roller.

C Effect] The document hanging down toward the idler roller is lifted by the document support roll having approximately the same diameter as the idler roller.

This prevents the document from sagging, and it is possible to obtain a copied image with uniform horizontal magnification.

〔Example〕

FIG. 1 is a diagram showing an embodiment of an idler roller, which is a main part of the present invention, as viewed from the front in the direction in which the document is fed. In the figure, a drive roller 20 is composed of a plurality of drive rolls 21 attached to a rotating shaft. The idler roller 22 located below the drive roller 20 is composed of a plurality of idler rolls 23 attached to a rotating shaft. Of these, document support rolls 24, which have approximately the same diameter as the idler roll 23 and a slightly larger width, are attached to the idler roller 22 at predetermined intervals on the same rotating shaft so as not to contact the drive roll 21.

Therefore, the document is transferred to the idler roll 2 of the idler roller 22.
3, the portion not pushed by the idler roll is also lifted by approximately the same amount Q by the document support roll 24. This prevents the document from sagging. In this case, the outer diameter of the document support roll 24 does not have to be the same as the outer diameter of the idler roll 23, and may be slightly different. Further, the larger the width of the document support roll 24 is, the more effective it is in preventing sagging.

〔Effect of the invention〕

As described above, according to the present invention, since the document support rolls are attached to the idler roller at predetermined intervals, it is possible to prevent the document from sagging at a conveyance location where the idler roller is located below the drive roller. the result,
Copy images with uniform lateral magnification can be obtained. Also, by eliminating slack in the width direction, the slack part is
It also prevents the lines from being cut off or shifting in the width direction.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of an idler roller which is a main part of the present invention, and FIG. 2 is a sectional view showing a schematic structure of a document conveying device. 1... Original transport path, 2... Optical unit, 3...
・Platen glass, 4...White platen roller, 6,
7゜12.20...Drive roller, 8,10.11
22...Idler roller, 21...Drive roll, 23...Idler roll, 24...Document support roll.

Claims (1)

[Claims] A drive roller has a plurality of drive rolls of the same diameter attached to a rotating shaft rotationally driven by a motor, and a plurality of idler rolls corresponding to each drive roll of this drive roller are attached to the same rotating shaft, and each In a document conveying device consisting of a drive roll and an idler roller that conveys a document by sandwiching the document between the idler roller, a document support roll having approximately the same diameter as the idler roller is placed on the rotation axis of the idler roller so as not to come into contact with the drive roller. A document conveying device characterized in that the document conveying device is arranged at predetermined intervals.