JPH1127455A - Picture reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive and sure reader independent of whether a document is narrow or wide and a bias or jam of a document does not occur by making a pressure of a part locating on an extension of a carrier roller higher than the pressure of other parts. SOLUTION: With regard to an elastic member 6, a central part 6a is different from both ends 6b in its length in a width direction. That is, the length in the width direction is made different by centering the central part opposing to a carrier roller 2. When an upper case is closed, the elastic member 6 is pressed, transformed and presses a sheet film 5 to the side of a contact type image sensor(CIS) 4 with a specified pressure. Since the sheet film 5 has a flexibility, a power for pressing the document to the CIS 4 is not uniformized, in a central part 6a it becomes high and in both sides 6b becomes small. Thus, for example, a difference between a load at the time of reading an A4 document and the one at the time of reading A3 document becomes small and even if the central part is given a carrier power by the carrier roller 2, couple hardly occurs and is possible to suppress a generation of a bias.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading a document image used in a facsimile machine, a digital copying machine or the like.

[0002]

2. Description of the Related Art Conventionally, a contact image sensor (CIS: Contact Image Sense) has been used as an image reading device provided in a copying machine, a facsimile machine, or the like.
The method using r) is known. As shown in FIGS. 6 and 7, the image reading apparatus using the CIS is configured such that originals stacked on an original mounting table (not shown) are separated one by one by a separation roller and a separation pressing piece pressed against the separation roller. Is transported between the transport roller 2 and the driven roller 3, and is transported between the CIS 4 and the white sheet film 5 by the transport roller 3. The sheet film 5 is attached to the upper case 7 by an adhesive tape 8, and the sheet film 5
The upper case 7 is in contact with the CIS 4 with a predetermined pressing force via an elastic member 60 such as a sponge provided on the back side of the original reading section. The document 1 sent between the CIS 4 and the sheet film 5 is conveyed while being pressed against the CIS 4 by a pressing force applied from the back. CI
In step S4, the image of the passing original 1 is photoelectrically converted and read.

When the document 1 is lifted up from the CIS 4, the focus of the CIS 4 is deviated and a reading trouble occurs. For this reason, as shown in FIG. 7, conventionally, an elastic body 60 having a width of almost the maximum original width is used to make the original close to the CIS 4 even when the original having the maximum width is conveyed. It is configured to apply a pressing force from the back.

[0004]

By the way, the transport roller 2 is formed to have a predetermined width from the center in the case of a center reference, for example. Further, as described above, the original 1 is conveyed while being pressed almost uniformly against the CIS 4 from the back surface of the original 1 to the entire width of the original for image reading.

When the original 1 is pressed against the CIS 4, a resistance is generated between the two. This resistance becomes a load on document conveyance. This load depends on the width of the original, and differs greatly between a narrow original and a wide original. For the different loads, in the case of the center reference, the transport roller 2 sends the original with the same transport force at the central portion of the original.
Insufficient conveying force for a wide original, causing a jam or skew of the original due to a couple acting on the entire original. Further, there is a problem that a load torque of a motor for driving the transport roller 2 increases.

Further, Japanese Patent Application Laid-Open No. 7-193681 (I
(PC: H04N 1/04), there is proposed an image reading apparatus for preventing skew of a document conveyed to a reading position. This is a CS that presses and transports the original onto the CIS.
The roller is divided into at least three parts in the axial direction, and the drive is transmitted only to the main roller corresponding to a substantially central portion of the document width,
The auxiliary rollers on both sides are rotatably supported by a rotating shaft.

[0007] In the above configuration, even when skew occurs, no couple is generated, and skew is not promoted. However, this configuration has the drawback that the configuration is complicated, such as the need to divide the roller into three parts, and the cost is high.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is an inexpensive and reliable document reading apparatus which does not cause skewing or jamming of a document regardless of whether the document is narrow or wide. The purpose is to provide.

[0009]

An image reading apparatus according to the present invention comprises: reading means for reading a document image; pressing means for pressing a document to the reading means; and conveying means for transferring the document to the reading means. And an image reading apparatus comprising:
The transport unit includes a transport roller having a predetermined width in the width direction of the document, and the pressing unit applies a pressing pressure of at least a portion located on an extension of the transport roller in a direction perpendicular to a sheet passing direction to another. It is characterized in that it is larger than the pressing pressure of the part.

In the case where the transport roller is located at the center of the center of the original in the width direction, the force for pressing the original to the reading means is largely increased in the central part in the direction perpendicular to the sheet-feeding direction on both sides. May be configured to be small.

In the case of the one-sided reference in which the transport roller is disposed at the reference end, the force for pressing the document to the reading means may be increased at the reference end and decreased at the opposite end. .

It is preferable that the width of a large force for pressing the original by the reading means is substantially equal to the minimum original width from the width of the transport roller.

As means for changing the force for pressing the original to the reading means, the width of the elastic member in the sheet passing direction is changed.

[0014] As means for changing the force for pressing the original to the reading means, the thickness of the elastic member is changed.

With the above-described configuration, the force for pressing the original against the reading unit is not uniform in the direction orthogonal to the sheet passing direction, and the load for reading the original with a small width and the reading force for reading the original with a large width are reduced. The load difference becomes small, and even if a conveying force is applied by the conveying roller, a couple hardly occurs, and the occurrence of skew can be suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those of the conventional example are denoted by the same reference numerals.

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention, and FIG. 2 is a perspective view of the essential part. The image reading apparatus according to the present embodiment is provided in a facsimile apparatus, is arranged on an upper portion of a facsimile main body, and is configured to convey and read a document based on a center.

This facsimile apparatus has an automatic sheet feeder mechanism (not shown), and a plurality of documents stacked on a document table are separated one by one by a separation roller and a separation pressing piece pressed against the separation roller. You. The document 1 separated into one sheet is sent between the transport roller 2 and the driven roller 3. The transport roller 2 is fixed to a roller shaft 2a, and the roller shaft 2a is rotationally driven in a counterclockwise direction in the figure by a drive motor (not shown) to rotate the transport roller 2. The driven roller 3 is in contact with the conveying roller 2 with a predetermined contact force. In the present embodiment, the driven roller 3 has two driven rollers 3, 3 rotatably fitted on a roller shaft 3a. .

In this embodiment, since the image reading apparatus is constructed on the basis of the center, the transport roller 2 is arranged at the center of the document in the width direction. And
As the width of the conveying roller 3 increases, the cost increases and the load on the motor also increases. In this embodiment, the width is about 20 to 30 mm.

The document 1 sent between the transport roller 2 and the driven roller 3 is sent between the CIS 4 and the white sheet film 5 by the transport force of the transport roller 3. The sheet film 5 is made of a flexible white polyester film or the like. The sheet film 5 is attached to the upper case 7 with an adhesive tape 8. Further, an elastic member 6 such as a sponge is fixed to the back surface of the sheet film 5 at a position where the sheet film 5 comes into contact with the image reading section of the CIS 4.

The elastic member 6 has a central portion 6a and both ends 6b.
Is different from the paper passing direction in the width direction. That is,
The length in the width direction is made different in a direction orthogonal to the paper passing direction with a center portion facing the transport roller 2 as a center.
In this embodiment, a large portion of the central portion 6a in the width direction is larger than the width of the transport roller 2 and smaller than the minimum document width. The width direction of both end portions 6b is almost half the width of the central portion 6a.

When the upper case 7 is closed, the elastic member 6 is pressed and deformed by the iron plate below the upper case 7, and the CIS is deformed.
The sheet film 5 is pressed against the 4 side with a predetermined pressure. Therefore, the sheet film 5 is pressed against the CIS 4 with a predetermined pressing force via the elastic member 6.

Then, as shown in FIG.
Since the central portion 6a and the opposite end portions 6b have different lengths in the width direction and the sheet film 5 has flexibility, the force pressing the original 1 against the CIS 4 is in a direction orthogonal to the paper passing direction. Therefore, the central portion 6a is large and both sides 6b are small. Therefore, depending on the shape of the elastic member 6, for example, the pressing force for suppressing the A4 width can be set to be large, and the pressing force for a portion having a width larger than that can be set to be small.

As a result, for example, the difference between the load at the time of reading the A4 document and the load at the time of reading the A3 document becomes small, and even if the transporting force is applied to the central portion of the document 1 by the transporting roller 2, the couple hardly occurs. And the occurrence of skew can be suppressed.

With the above configuration, the upper case 7
As a result, the original 1 is fed between the CIS 4 and the sheet film 5 by the predetermined pressing force of the sheet film 5 via the elastic member 6 without causing skewing or jamming, and the original 1 is driven by the driving force of the transport roller 2. Document reading section. Then, the original 1 is conveyed while being pressed against the CIS 4 by the pressing pressure applied from the back, and
The image of the original 1 through which the image passes 4 is photoelectrically converted and read.

Even when the original having the maximum width is conveyed, the pressing force is small at both ends as compared with the central portion due to the sheet film 5, but a predetermined pressing force is applied, so that both ends do not float.

In the first embodiment, the width of the central portion 6a and the width of both ends 6b of the elastic member 6 are made different from each other so that the pressing force is not made uniform, as shown in FIG. In the second embodiment, the elastic member 6 is disposed only at the center, and the elastic members are not provided at both ends. Even in such a configuration, when the upper case 7 is closed, the elastic member 6 is pressed and deformed by the iron plate below the upper case 7 and presses the sheet film 5 against the CIS 4 with a predetermined pressure. Therefore, the sheet film 5 is pressed against the CIS 4 with a predetermined pressing force about the center elastic member 6.

Then, as shown in FIG.
Since the elastic member does not exist at both ends, the force for pressing the original 1 against the CIS 4 is not uniform in the direction orthogonal to the paper passing direction, and the central part is large and both sides are small. Become. The pressing forces at the center and both ends are different.

In the third embodiment shown in FIG. 4, the length of the first embodiment shown in FIG. 2 is different in the width direction in the sheet passing direction, whereas the length is different in the height direction. The thickness of the member 6 is changed. That is, the height of the central portion 6a is high,
The height b is configured to have a low step.

Even in such a configuration, when the upper case 7 is closed, the elastic member 6 is pressed and deformed by the iron plate below the upper case 7 and presses the sheet film 5 against the CIS 4 with a predetermined pressure. Therefore, the sheet film 5 is pressed against the CIS 4 with a predetermined pressing force via the elastic member 6.

Then, as shown in FIG.
The central portion 6a and both end portions 6b have different heights,
Since the sheet film 5 has flexibility, the force pressing the original 1 against the CIS 4 is not uniform in the direction perpendicular to the sheet passing direction, but the central portion 6a is large and both sides 6b are small.

The fourth embodiment shown in FIG. 5 differs from the third embodiment shown in FIG. 4 in that the heights of the central portion 6a and both ends 2b are changed. It is configured so that it gradually decreases as it goes to both ends.

Similarly, in this embodiment, the original 1 is
The force pressing against 4 is not uniform, but the center part is large and becomes smaller toward both ends.

In the above-described embodiment, the center reference has been described. However, a single-side reference may be similarly formed. That is, in the case of the one-sided reference, the pressing force is increased at a position corresponding to a portion where the transport roller is located,
The difference in the pressing force may be obtained by increasing the width of the elastic member in the width direction or the height direction and reducing or eliminating the other portions.

[0035]

As described above, according to the present invention, the force for pressing the original against the reading means is not uniform in the direction perpendicular to the sheet passing direction, and the load for reading the original with a small width is large. The difference in the width of the load at the time of reading the document is reduced, and even when a conveying force is applied by the conveying roller, a couple hardly occurs, and the occurrence of skew can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part showing the first embodiment of the present invention.

FIG. 3 is a perspective view of a main part showing a second embodiment of the present invention.

FIG. 4 is a perspective view of a main part showing a third embodiment of the present invention.

FIG. 5 is a perspective view of a main part showing a fourth embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a conventional image reading apparatus.

FIG. 7 is a perspective view of a main part of a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original 2 Conveyance roller 3 Follower roller 4 CIS 5 Sheet film 6 Elastic member

Claims (6)

[Claims] A reading means for reading a document image;
In an image reading apparatus comprising: a pressing unit that presses a document to the reading unit; and a conveyance unit that conveys the document to the reading unit, the conveyance unit includes a conveyance roller having a predetermined width in a width direction of the document. The image reading apparatus according to claim 1, wherein the pressing unit makes a pressing pressure of at least a portion located on an extension of the transport roller in a direction perpendicular to a paper passing direction larger than a pressing pressure of another portion. 2. The image forming apparatus according to claim 1, wherein the conveying roller is disposed at a central portion in a width direction of the document, and increases a central portion in a direction perpendicular to a sheet passing direction with a force for pressing the document to the reading means, and reduces both sides. The image reading device according to claim 1. 3. The apparatus according to claim 1, wherein the transport roller is disposed on a reference end side, and a force for pressing the document to the reading unit is increased on the reference end side and reduced on the opposite side. Image reading device. 4. The image reading apparatus according to claim 1, wherein a width at which the force for pressing the document by the reading unit is large is substantially the minimum document width from the width of the transport roller. 5. The image reading apparatus according to claim 1, wherein the means for changing the force of pressing the document on the reading means changes a width of an elastic member in a sheet passing direction. . 6. The image reading apparatus according to claim 1, wherein a thickness of an elastic member is changed as a unit for changing a force of pressing the document on the reading unit.