JP3548427B2 - Image reading device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading device that reads an image (information) of a document.
[0002]
This image reading apparatus is used for an image forming apparatus such as a copying machine and a facsimile. Or use alone.
[0003]
[Prior art]
FIG. 5 shows a configuration of a conventional image reading apparatus provided in a copying machine, a facsimile, or the like.
[0004]
The image reading apparatus 100A can read a sheet-like original such as a document and a thick original such as a book.
[0005]
The reading of the document is performed by a reading optical system (image reading unit) 102 installed below the platen glass 101.
[0006]
The reading optical system 102 forms an image on the irradiation unit 102-1 for irradiating the original surface, the reflecting unit 102-2 for reflecting light reflected from the original surface in a predetermined direction, and the light reflected on the reflecting unit 102-2. The imaging apparatus includes an imaging unit (not shown), a photoelectric conversion unit (not shown) that photoelectrically converts light formed by the imaging unit, and the like.
[0007]
The irradiating unit 102-1 is movable in the directions of the arrows X1 and X2 (sub-scanning direction), and the reflecting unit 102-2 is fixed at the illustrated position.
[0008]
The sheet document is placed on the document table 103. Then, the document is conveyed one by one to the image reading unit A on the document table glass 101, and the image is read by the reading optical system 102. In this case, the irradiation unit 102-1 is stationary at a position where the reflected light path P matches the image reading unit A.
[0009]
A sheet-shaped document (not shown) placed on the document table 103 is sequentially moved from a top sheet document by a preliminary transport roller 104-1 rotating in a counterclockwise direction and a document pressing plate 104-2. Will be sent out.
[0010]
With respect to the sheet-shaped original sent out from the original mounting table 103, only the uppermost sheet original is separated into one sheet by the separation roller 105-1 and the separation piece 105-2 rotating in the counterclockwise direction, and is conveyed.
[0011]
The sheet-shaped original conveyed by the separation roller 105-1 is nipped by a paper feed roller 106-1 rotating in a counterclockwise direction and a roller 106-2 (first original conveying means) and is placed on the original platen glass 101. To the image reading unit A.
[0012]
A white plate 107 is installed in the image reading unit A on the platen glass 101. The sheet-shaped original conveyed by the paper feed roller 106-1 and the roller 106-2 moves downstream through a minute gap below the white plate 107, and is driven by a discharge roller 108-1 rotating clockwise. The sheet is nipped by a roller 108-2 (second document conveying means) and discharged onto a discharge tray 109 outside the apparatus.
[0013]
The document transport path through which the sheet-shaped document sent from the document table 103 to the image reading unit A passes is lowered downstream from the separation roller 105-1 to the white plate 107, and is discharged from the white plate 107 to the discharge roller. It is substantially horizontal until 108-1.
[0014]
In the case of the image reading apparatus 100A, the sheet-shaped document passing through the image reading unit A is fed with the paper feed roller 106-1 and the roller 106-1 until the leading edge of the document enters the nip between the discharge roller 108-1 and the roller 108-2. -2 only (first transport mode).
[0015]
After the leading end of the document enters the nip between the discharge roller 108-1 and the roller 108-2, the document is conveyed by both the sheet supply roller 106-1 and the roller 106-2 and the discharge roller 108-1 and the roller 108-2. (Second transport mode).
[0016]
After the trailing end of the document has passed through the nip between the feed roller 106 and the roller 106-2, the document is conveyed only by the discharge roller 108-1 and the roller 108-2 (third conveyance mode).
[0017]
Here, in the above-described second transport mode, in order to transport the sheet-like document while the discharge roller 108-1 and the roller 108-2 slide, the document transport speed V1 of the paper feed roller 106-1 and the document transport The relationship between the force F1, the document conveying speed V2 of the discharge roller 108-1, and the document conveying force F2 is set to V1 <V2, F1> F2.
[0018]
The thick original is placed on a position indicated by the index member 110 on the original platen glass 101. The surface of the index member 110 on the side in contact with the document table glass 101 is white.
[0019]
When reading an image of a thick original, the irradiation unit 102-1 moves and reads the image of the original that is stationary on the original platen glass 101 in the direction of the arrow X2. In this case, the irradiation unit 102-1 moves in the direction of arrow X2 from the reading start position C, but before that, temporarily stops at the position B below the index member 110, reads the white level of the index member 110, and reads the white level of the original. Before reading an image, shading correction for setting a reference white level is performed.
[0020]
[Problems to be solved by the invention]
However, in the above-described conventional image reading apparatus, the conveying speed of the sheet original in the image reading unit A is unstable, the conveying speed of the sheet original in the image reading unit A changes suddenly, There has been a problem that the behavior of the sheet-shaped original in the section A is unstable or the quality of the read image is reduced. Hereinafter, this will be described in detail.
[0021]
{Circle around (1)} When a sheet-shaped document is being conveyed in the first conveyance mode, the sheet-shaped document is slackened. This slack is gradually removed when the sheet-shaped document is being conveyed in the second conveyance mode.
[0022]
As a result, the conveyance speed of the sheet-shaped document in the image reading unit A becomes unstable. In this case, the image read by the reading optical system 102 undergoes remarkable partial expansion and contraction in the sub-scanning direction, and the quality of the read image deteriorates.
[0023]
It should be noted that the slack is gradually removed from the sheet-shaped document conveyed in the second conveyance mode because of the document conveyance speed (V1, V2) of the paper feed roller 106-1 and the discharge roller 108-1 and the document conveyance. This is because the relationship between the forces (F1, F2) is set as described above.
[0024]
{Circle around (2)} When a tension is generated between the sheet feeding roller 106-1 and the discharge roller 108-1 of the sheet-shaped document being conveyed in the second conveyance mode (many of long documents), the trailing edge of the document The tension is suddenly released at the moment when the sheet passes through the paper feed roller 106-1.
[0025]
As a result, the conveyance speed of the sheet-shaped document in the image reading unit A changes abruptly, and a step due to the sudden change in the conveyance speed occurs in the image read by the reading optical system 102, thereby deteriorating the read image quality.
[0026]
{Circle around (3)} While the sheet document is being conveyed in the second conveyance mode, the slack is not completely removed, and the rear end of the document may pass through the paper feed roller 106-1 (often a short document).
[0027]
In this case, the behavior of the sheet-shaped document in the image reading unit A becomes unstable, and a step occurs due to a change in the behavior of the image read by the reading optical system 102, and the quality of the read image deteriorates.
[0028]
Accordingly, the present invention has been made in view of the above-described circumstances, and (1) does not make the conveyance speed of the sheet-shaped original in the image reading section unstable, and (2) conveys the sheet-shaped original in the image reading section. (3) It is an object of the present invention to provide an image reading apparatus capable of improving the quality of a read image by preventing the behavior of a sheet-shaped original from becoming unstable in an image reading section without a sudden change in speed.
[0029]
[Means for Solving the Problems]
The present invention for achieving the above object,
Image reading means for reading an image of a sheet-shaped document moving on the image reading unit,
First document conveying means for nipping and conveying the sheet-shaped document to the image reading unit;
Second document conveying means for pinching and conveying the sheet-shaped document that has passed through the image reading unit;
The present invention relates to an image reading device provided with:
[0030]
And the present invention, in order to achieve the above object,
Have a document pressing means for elastically pressing the sheet-like document is moving pre-reading conveying path on the road surface of the pre-reading conveying path between the first document conveying means and the image reading unit,
The document pressing unit is an elastic sheet member that is in surface contact with the road surface of the pre-reading conveyance path in the document conveyance direction,
The elastic sheet member is formed in an arch shape, and the arch portion is in surface contact with the road surface of the pre-reading conveyance path .
[0031]
Document guide means for guiding the leading end of a sheet-shaped document moving on the post-reading conveyance path between the image reading unit and the second document conveyance means to the second document conveyance means,
It is characterized by the following.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0033]
FIG. 1 shows the configuration of an image reading apparatus according to the present invention. FIG. 2 is an enlarged view of a main part (invention part) of the image reading apparatus.
[0034]
The image reading apparatus 100B is used for a copying machine, a facsimile, and the like. The basic configuration is not different from the conventional image reading apparatus 100A. Therefore, here, only the characteristic portions of the image reading apparatus 100B will be described. The same members are given the same reference numerals.
[0035]
The image reading apparatus 100B has two characteristic portions. One is that a document pressing sheet (resin sheet) 111 is provided in the pre-reading conveyance path 110 between the image reading unit A and the paper feed roller 106-1. This is the point that a document guide sheet (resin sheet) 113 is provided in the post-reading conveyance path 112 between the roller 108-1.
[0036]
The document pressing sheet 111 plays a role of elastically pressing a sheet-shaped document moving on the pre-reading conveyance path 110 against a road surface.
[0037]
The pre-reading conveyance path 110 is formed by an upper guide 110-1, a lower guide 110-2, and a lower guide sheet (resin sheet) 110-3 for guiding a document to the image reading unit A.
[0038]
The document pressing sheet 111 is attached (attached) to the upper guide 110-1 in such a manner that the upstream end 111-1 and the downstream end 111-2 are bent in an arched shape as shown by imaginary lines. Then, the arch-shaped portion is deformed and is in full contact with the lower guide 110-2 and the lower guide sheet 110-3. Although the lower guide sheet 110-3 is attached in the state shown by the imaginary line, the lower guide sheet 110-3 is pressed by the arch-shaped portion to be in the state shown by the solid line.
[0039]
FIG. 4 shows the position of the paper feed roller 106-1, and FIG. 3 shows the positions of the roller 106-2 and the document pressing sheet 111.
[0040]
The document pressing sheet 111 presses the sheet-shaped document moving on the pre-reading conveyance path 110 against the road surface from the lower guide 110-2 to the lower guide sheet 110-3.
[0041]
For this reason, the sheet-shaped document moving along the pre-reading conveyance path 110 does not sag, and the document conveyance speed in the image reading unit A is stabilized. Further, even if the tension of the sheet-shaped document is suddenly released at the moment when the trailing end of the sheet-shaped document has passed through the paper feed roller 106-1, the image reading unit A is in a state where the document pressing sheet 111 is a transport load. Document conveyance speed does not change suddenly.
[0042]
The document guide sheet 113 serves to guide the leading end of the sheet-shaped document moving on the conveyance path 112 after reading to the nip between the discharge roller 108-1 and the roller 108-2.
[0043]
The post-read transport path 112 is formed by an upper guide 112-1 and a lower guide 112-2.
[0044]
The document guide sheet 113 is attached (sticked) to the upper guide 112-1. The leading end of the document guide sheet 113 contacts the outer periphery of the discharge roller 108-1 near the nip between the discharge roller 108-1 and the roller 108-2. I have.
[0045]
FIG. 3 shows the positions of the discharge roller 108-1 and the document guide sheet 113.
[0046]
The sheet-shaped document conveyed only by the paper feed roller 106-1 and passed through the image reading unit A has a slack in the conveyance path 112 after reading, but the leading end of the sheet-shaped document is discharged by the document guide sheet 113 to the discharge roller 108-. It is smoothly guided to the nip between the roller 1 and the roller 108-2. As a result, the conveyance speed of the sheet original in the image reading unit A does not become unstable.
[0047]
【The invention's effect】
As described above, according to the present invention, a sheet-like document moving on the pre-reading conveyance path between the first document conveyance unit and the image reading unit is elastically applied to the road surface of the pre-reading conveyance path by the document pressing unit. Since the pressing is performed, the sheet-shaped document moving on the pre-reading conveyance path does not sag. For this reason, the document conveyance speed in the image reading unit is stabilized, and the quality of the read image is improved.
[0048]
Further, even if the tension of the sheet-shaped document is suddenly released at the moment when the trailing end of the sheet-shaped document has passed through the first document-conveying means, the document-pressing means becomes a conveying load, so The conveyance speed of the sheet-shaped document does not suddenly change, and the quality of the read image is improved.
[0049]
Further, the leading end of the sheet-like document moving on the post-reading conveyance path between the image reading unit and the second document conveyance means is smoothly guided to the second document conveyance means by the document guide means. The document conveying speed in the reading section does not become unstable, and the quality of the read image is improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a configuration of an image reading apparatus according to the present invention.
FIG. 2 is an enlarged sectional view showing a configuration of a main part (invention part) of the image reading apparatus of FIG. 1;
FIG. 3 is a plan view illustrating a configuration of a main part of the image reading apparatus of FIG. 1;
FIG. 4 is a plan view showing a configuration of a main part of the image reading apparatus of FIG. 1;
FIG. 5 is a cross-sectional view illustrating a configuration of a conventional image reading apparatus.
[Explanation of symbols]
102 Reading optical system (image reading means)
106-1 Paper feed roller (first document conveying means)
106-2 Roller (First Document Conveying Means)
108-1 Discharge Roller (Second Document Conveying Means)
108-2 roller (second document conveying means)
111 Document pressing sheet (document pressing means)
113 Document Guide Sheet (Document Guide Means)
A Image reading unit

Claims (4)

Image reading means for reading an image of a sheet-shaped document moving on the image reading unit,
First document conveying means for nipping and conveying the sheet-shaped document to the image reading unit;
Second document conveying means for pinching and conveying the sheet-shaped document that has passed through the image reading unit;
In an image reading apparatus comprising:
Have a document pressing means for elastically pressing the sheet-like document is moving pre-reading conveying path on the road surface of the pre-reading conveying path between the first document conveying means and the image reading unit,
The document pressing unit is an elastic sheet member that is in surface contact with the road surface of the pre-reading conveyance path in the document conveyance direction,
The image reading apparatus , wherein the elastic sheet member is formed in an arch shape, and the arch-shaped portion is in surface contact with a road surface of the pre-read conveyance path . Document guide means for guiding the leading end of a sheet-shaped document moving on a post-reading conveyance path between the image reading unit and the second document conveyance means to the second document conveyance means,
The image reading device according to claim 1, wherein: An elastic sheet member is used for the document guide means.
The image reading device according to claim 2 , wherein: The pre-reading conveyance path is formed by an upper guide, a lower guide, and a lower guide sheet that guides a document to the reading unit, and the elastic sheet member is attached to the upper guide in an arch shape, and forms the arch shape. The image reading apparatus according to claim 1 , wherein the image reading device is deformed and is in contact with the lower guide and the lower guide sheet .

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