JP2002284388A - Document carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document carrying device capable of restricting the generation of waviness in a document and vertical line bend of an image. SOLUTION: This document carrying device is used for a document reading device for scanning the document by exposing it, carrying the document between a fixed contact glass and a backup member arranged opposite to the contact glass, and formed by arranging several driven rollers facing to a document carrying roller in a nearly inverted V-shape symmetrically in relation to the center line of the document in the cross direction thereof. A central part of the document carrying roller is formed to be displaced to the downstream in the document carrying direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder, and more particularly, to a document feeder for an image forming apparatus such as a copying machine, an image reading device, and a facsimile.

[0002]

2. Description of the Related Art In a conventional document conveying apparatus, when a document is conveyed by a conveying roller, when the document passes a conveying roller portion disposed before and after a contact glass, the document is moved to the center due to uneven conveyance. Therefore, there is a problem in that the original is wavy, and depending on the degree of the waving, the original is wrinkled. This is a problem particularly when the sheet original is made of thin paper.

In addition, the undulation of the original is eliminated immediately after the original has passed through the original conveying roller on the upstream side of the reading portion of the contact glass, so that a vertical line in the sub-scanning direction is bent when the original is scanned. However, there has been a problem that the scanned document image is distorted compared to the original document.

A problem which has occurred in the conventional document feeder will be described with reference to FIGS.

FIGS. 3 and 4 are diagrams showing a wavy state of the original due to the deviation of the original when the original is transported, and a vertical line curved image.

FIG. 3 shows a document waving state, that is, when a document wavy document is ejected from the document feed roller 5 at the trailing end of the document, the document is moved in the width direction due to the waist of the paper, as in a document 8a indicated by a dashed line. Shows a state that has spread.

When a document is conveyed in the direction indicated by arrow A, the diameter of the plurality of document conveying rollers provided in a comb-like shape in the width direction of the document and the pressure of the driven roller 10 vary. This is because the original is moved to the center. As an example, when the outer document transport roller diameter is smaller than the central document transport roller diameter, the transport speed near the center of the document becomes faster than the transport speed near both ends of the document. As a result, the document was wavy, causing a problem.

FIG. 4 shows a document 8 in a state in which a vertical line is bent in the document.
b. In other words, the vertical line of the scanned image shows the state of the image in which the vertical line is curved, as the vertical line of the scanned image is gradually inclined inward due to the center of the original and is discharged when the original is discharged from the original conveying roller 5. . In this state,
When the document is conveyed in the direction indicated by arrow A, the document is instantaneously spread due to the waist of the document at the moment when the rear end of the document is discharged from the conveyance roller on the upstream side of the reading line position. There has been a problem that a straight line in the direction becomes a curved image.

Further, even when the pressure of the driven roller is strong in the central portion, the transport speed in the central portion is increased, and the same phenomenon occurs, causing a problem.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a document feeder which reduces the wavy and vertical curved images of a document.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is applied to a document reading apparatus which performs exposure scanning while conveying a document between a fixed contact glass and a backup member opposed thereto. A document feeder in which a plurality of driven rollers opposed to a document feed roller are arranged in a substantially C-shape so as to be line-symmetric with respect to the center line in the width direction of the document as a symmetric axis; The section is displaced downstream in the document transport direction.

According to another aspect of the present invention, a core of the document transport roller has an elastic strength capable of being displaced, and a bearing at the center of the document transport roller is provided so as to be displaceable in the document transport direction. It is characterized by having.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

First, the configuration of the document feeder according to the present embodiment will be described.

FIGS. 1 and 2 are diagrams showing an embodiment of a document feeder according to the present invention, in which the document feeder is applied to a sheet document feed type image reading apparatus.

In FIGS. 1 and 2, each section of a document feeder applied to an image reading apparatus includes a contact glass 1, a light source 2, a self-focus lens array 3, a backup roller 4, document feed rollers 5, 6, a CCD 7, and a document 8. , Driven rollers 9, 10, guide plates 11, 13, 15, 16, side plate 3
1, 32, bearing 36, drive belt 33, drive pulley 3
4,35.

The original transport rollers 5 and 6 are original transport rollers for the original transport roller 5 to insert the original, and the original transport rollers for the original transport roller 6 to discharge the original. The original 8 is conveyed in the direction.

The sheet document 8 is irradiated by the light source 2 while being conveyed at a constant speed by rotating the document conveying rollers 5 and 6 in the direction of the arrow shown by the document conveying rollers 5 and 6 by driving means (not shown). It has become so.

The reflected light from the sheet document 8 illuminated by the light source 2 is imaged on the CCD 7 by the SELFOC lens array 3 so that an image signal is extracted as an electric signal.

The backup roller 4 is provided on an arm 20 pivotally supported on a fulcrum shaft 21 as a fulcrum, and is pressed in the direction of the contact glass 1.

The backup roller 4 is rotated by driving means (not shown), and conveys the original in the same direction as the rotation direction of the backup roller 4. The peripheral surface of the backup roller 4 is preferably white.

Flange rollers 19 slightly larger than the backup roller diameter are provided at both end positions outside the document readable range, and a slight gap is provided between the contact glass 1 and the backup roller 4. This prevents the contact between the backup roller 4 and the contact glass 1 and damages.

The guide plates 11 and 13 are provided with resin sheets 12 and 14 on the side adjacent to the backup roller 4.

In FIG. 2, the original transport rollers 5,
The driven rollers 9 and 10 opposing the roller 6 are constituted by a pair of driven rollers symmetrically with respect to the central portion of the document transport, and the shaft 41 presses the document transport rollers 5 and 6 against a holder (not shown). The original conveying rollers 5 and 6 are pressed by pressing means such as a compression spring 17.
To be pressurized.

The pair of driven rollers 9 and 10 are rotatably inserted into the shaft 41, the thrust direction is regulated by the holder, and the driven rollers 9 and 10 are arranged in a substantially C shape.

At the center of the original transport rollers 5 and 6, there is provided a sliding bearing 50 whose displacement can be adjusted in the original transport direction. The sliding bearing 50 is displaced to the downstream side in the original transport direction to thereby transport the original. The rollers are set in a curved state.

The metal cores of the original transport rollers 5 and 6 have a displaceable elastic strength in order to install the original transport rollers in a curved state. Also, if the degree of curvature of the document conveying roller is too large, internal stress is repeatedly applied to the shaft, the shaft is damaged by metal fatigue, the radial load on the bearing increases, and the durability of the bearing decreases. Sometimes.

Therefore, the degree of curvature of the document conveying roller is
When the material is stainless steel, the shaft diameter is 8 mm, and the distance between the side plates is 980 mm, it is preferable that the central portion of the document conveying roller is bent by about 2 mm.

In the document feeder of the present invention, with such a configuration, the bending angle of the shaft increases from the center to the outside, so that the acting force for directing the document to the outside increases. . Therefore, it is possible to prevent the original from moving inward, and to provide an image without the vertical line curving of the original.

Further, the original conveying apparatus of the present invention has a configuration in which one original conveying roller shaft is bent to fix the position, so that the bent portion swings in the original conveying direction in the original conveying direction with the conveyance of the sheet original. Movement can be prevented.
Therefore, the document can be transported stably.

As another embodiment, the original conveying roller is divided into two parts, and the central part is connected by a universal joint or the like so that the radial load of the bearing provided at the central part is eliminated. You may.

[0032]

According to the present invention, since the central portion of the original transport roller is displaced downstream in the original transport direction, the original is shifted toward the center by obtaining the action force for spreading the original outward. Of the original document, and also the vertical line bending in the original transport direction can be prevented.

Further, according to the present invention, the mandrel of the manuscript conveying roller has a resilient strength capable of being displaced, and the bearing at the center of the manuscript conveying roller is provided so as to be displaceable in the manuscript conveying direction. The spreading force can be changed, the original document can be more appropriately prevented from waving due to the center of the original document, and the vertical line bending in the original transport direction can be more appropriately prevented.

Further, according to the present invention, since one roller shaft is bent to fix the position, the bent portion does not swing in the document transport direction in the downstream direction with the document transport. It is possible to more appropriately prevent the document from waving due to the document being shifted to the center, and it is possible to more appropriately prevent the vertical line from being bent in the document transport direction.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a document feeder according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a document feeder according to an embodiment of the present invention.

FIG. 3 shows a state in which a document is wavy due to a document skew in a conventional document feeder.

FIG. 4 illustrates a state in which a document is bent in a vertical line due to a document skew in a conventional document conveyance device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 contact glass 2 light source 3 self-lens array 4 backup roller 5, 6 document transport roller 7 CCD 8 document 9, driven roller 11 guide plate 12, 14 resin sheet 13, 15, 16 guide plate 17 compression spring 19 flange roller 20 Arm 21 fulcrum shaft 31, 32 side plate 33 drive belt 34, 35 drive pulley 36 bearing 41 shaft 50 slide bearing

Claims (2)

[Claims] The present invention is applied to a document reading apparatus that performs exposure scanning while transporting a document between a fixed contact glass and a backup member facing the fixed contact glass. In a document feeder arranged in a substantially C-shape so as to be line-symmetric with respect to the center line in the width direction of the document, the central portion of the document feed roller is displaced downstream in the document feed direction. Document transport device. 2. The document conveying roller according to claim 1, wherein a core metal of the document conveying roller has an elastic strength capable of being displaced, and a bearing at a central portion of the document conveying roller is displaceable in a document conveying direction. Document feeder.