JP2003140273A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make readable an image with high quality by setting a read position in browsing with high precision while preventing a ground fogging in book reading. SOLUTION: A platen roller 201 having a 1st external-diameter part 201A which limits flotation of a document and a 2nd external-diameter part 201B set at the maximum light-quantity position of a lighting means 111 within the read range of an image read sensor 110, is characterized in that and the image read sensor 110 scans the circumference of the platen roller to detect the roller center position from the peak of luminance level on the roller surface of the 2nd external-diameter part 201B.

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 which is installed in an image reading unit such as a facsimile or a copying machine or used as an image input apparatus for a computer, and more particularly to moving a stationary document. The present invention relates to an image reading apparatus capable of reading both a first image reading method of scanning by a reading means for reading and a second image reading method of reading a moving original by a stationary reading means.

[0002]

2. Description of the Related Art Conventionally, as an image reading apparatus for a copying machine, a facsimile, etc., in addition to a first image reading method (hereinafter referred to as a book reading method) for reading an original on a platen by a reading means, an original conveying apparatus. A device having a second image reading method (hereinafter referred to as a flow reading method) for reading a sheet-like document conveyed by (hereinafter referred to as ADF) is used.

The book reading method has an advantage that the degree of freedom of the form of the original is high and that a book-like original or a three-dimensional object can be read. Further, the flow-reading method has an advantage that a large number of sheet-shaped originals can be automatically processed in a short time.

FIG. 4 shows an example of a conventional image reading apparatus.

The image reading apparatus shown in FIG. 4 is provided with a platen glass 1121 for a book reading method, a flow reading glass 1122 for a flow reading method, and an image reading sensor 1110 shared by both reading methods. . The image reading sensor 1110, as shown in an enlarged view in FIG. 5, is an LED and a light guide which are illumination means 1111 for illuminating the original on the original table glass 1121, and a SELFOC lens 1112 for forming an image of reflected light from the original. Furthermore, the image sensor 1113 arranged at the image forming position of the SELFOC lens is
It is integrally contained in the casing 1114. The casing 1114 is an abutting member (not shown) having high slidability.
With the platen glass 1121 or the scanning glass 1122
The image reading sensor 1110 is placed at a predetermined distance from the document. The image reading sensor 1
The readable range of 110 is the effective width of the platen glass 1121 in the main scanning direction and the automatic document feeder (ADF) 1.
By 002, the width of the document size that can be conveyed is substantially the entire width in the main scanning direction. In addition, the image reading device 1001
An automatic document feeder 1002 is attached to the upper part of the document platen glass 11 so that it can be opened and closed.
It functions as a pressure plate fixed on 21.

In the case of the book reading system, the platen glass 11
The document placed on 21 is fixed by the automatic document feeder 1002, and the document is read while the image reading sensor 1110 is driven in the sub-scanning direction at a predetermined speed.

In the case of the flow reading method, the image reading sensor 11
Reference numeral 10 is fixed below the flow-reading glass 1122, and the automatic document feeder 1002 reads a document conveyed on the flow-reading glass 1122 in the sub-scanning direction at a predetermined speed.

In the flow-reading method, in order to read a high-quality image without blurring or blurring, it is necessary to prevent the original from floating from the upper surface of the flow-reading glass 1122 at the reading position and stably convey it at a constant speed. For this reason, the automatic document feeder 1002 of FIG. 4 includes a platen roller 1201. The platen roller 1201 is arranged at a predetermined distance (C: 0.2 mm in this example) from the upper surface of the flow reading glass 1122, and is rotationally driven at a predetermined speed. As a result, it is possible to stably convey the original while limiting the floating amount of the original from the upper surface of the reading glass 1122.

In the flow reading using the platen roller 1201, the document is regulated within the space between the platen roller 1201 and the flow reading glass 1122 just below the platen roller 1201, but at a position separated upstream or downstream of the platen roller 1201. Then, floating from the upper surface of the flow reading glass 1122 is likely to occur. Further, dust is likely to adhere to the upper surface of the flow reading glass 1122 slightly downstream of the center of the roller. In order to avoid these effects and perform stable reading, the image reading sensor 1110 is set to the platen roller 1
It is necessary to accurately position it at a predetermined position with respect to the center of 201. In this conventional example, it is optimal that the reading position is 0.5 mm upstream from directly below the center of the platen roller 1201, and it is desirable to read within ± 0.5 mm from this position.

However, the automatic document feeder 10 according to this conventional example.
Since 02 is a structure that can be opened and closed as a pressure plate during the book reading method, it is difficult to position the platen roller 1201 with high precision due to the play of the hinge portion. Further, since the image reading sensor 1110 is used commonly for book reading and flow reading, the image reading sensor 1110 cannot be fixed at the flow reading position. Therefore, in order to position the image reading sensor 1110 with reference to the platen roller 1201 center with high accuracy, the platen roller 1
201 It is necessary to detect the center position.

As a roller center position detecting method, a method of directly detecting the center position of the platen roller 1201 by the image reading sensor 1110 is desirable because it can remove the influence of component accuracy and assembly accuracy.

As a method thereof, a method of illuminating the platen roller 1201 by the illuminating means 1111 while driving the image reading sensor 1110 near the reading position in the flow reading method and reading the brightness of the surface of the platen roller 1201 by the image reading sensor 1110 is used. There is. The distance between the surface of the platen roller 1201 and the illuminating means 1111 is minimum near the center of the roller and increases as the distance from the center is increased. Therefore, the brightness level of the surface of the platen roller 1201 read by the image reading sensor 1110 is determined by the image reading sensor 1110. Is almost maximum when passing under the center of the roller, and the center of the platen roller 1201 is detected.

[0013]

By the way, when a document is lifted from the platen glass 1121, the density of the image read only in that part is increased. This is because generally, when the distance between the document and the illumination unit 1111 increases, the irradiation light amount decreases, and the amount of light reflected from the document surface incident on the image reading sensor 1110 decreases. In the book reading method, this phenomenon is particularly noticeable as "white background fog" in the floating portion between the pages of the two-page spread original, and deteriorates the image quality.

In order to reduce this "white background fog", FIG.
The light guide of the illuminating means 1111 shown in (1) is arranged so that the maximum amount of light can be obtained at a predetermined distance (H: 1 mm in this example) above the glass surface. As a result, even if the original floats from the glass surface, a sufficient amount of irradiation light can be obtained on the original surface, reducing white background fog between pages,
It is possible to prevent the occurrence of white background fog due to a slight floating of the original on the original table glass 1121.

However, the platen roller 1201 is illuminated by the illumination means 1111 of the conventional example, and the image reading sensor 1
When the brightness level of the surface of the platen roller 1201 is measured while moving 110 under the platen roller 1201 in the sub-scanning direction, a peak does not occur directly below the center of the roller,
There will be two peaks upstream and downstream of the center of the roller. Further, since the distribution of the brightness level near the roller is broad, it is difficult to detect the center of the roller with high accuracy.

The present invention has been made in view of the above problems, and an object thereof is to prevent the occurrence of background fogging during book reading, and to position the reading position during flowing reading with high precision, and to perform the following reading method. Accordingly, it is an object of the present invention to provide an image reading device capable of reading a high-quality image.

[0017]

In order to achieve the above object, according to the present invention, a document placed on a first translucent member is read and scanned by moving the reading device. And a second document reading unit configured to read and scan the sheet-shaped document conveyed by the document conveying unit to the second light-transmitting member while the reading unit is stationary. The document reading unit of the above includes a platen roller for suppressing the floating of the document from the second light transmitting member at the reading position,
The reading means has an illuminating means for illuminating the original through the first and second light transmitting members, and the amount of light by the illuminating means is the original passing surface of the first and second light transmitting members and the original placement. In the image reading apparatus configured to take the maximum amount of light at a position higher than the surface, the platen roller has a first outer diameter portion that limits the floating of the document within the reading range of the reading unit, and the illuminating unit. The second outer diameter portion is set to the maximum light amount position, the vicinity of the platen roller is scanned by the reading means, and the roller center position is determined from the peak of the brightness level of the roller surface of the second outer diameter portion. It is characterized in that it is configured to detect.

The height of the maximum light amount position of the illuminating means in the reading means from the original passing surface or the original placing surface is H, the outer diameter of the first outer diameter portion of the platen roller is D1, and the second outer diameter. If the outer diameter of the portion is D2, and the distance between the roller surface of the first outer diameter portion and the document passage surface of the second light transmitting member is C, then the relation H = C + (D1-D2) / 2 is set. It is characterized by being.

Further, it is preferable that the second outer diameter portion of the platen roller is set outside the original sheet passing area.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of the image reading apparatus of the present invention.

The image reading apparatus 1 shown in FIG. 2 includes a platen glass 121 as a first translucent member for a book reading system, and a flow reading glass 122 as a second translucent member for a flow reading system. Further, the image reading sensor 110 is provided as a reading unit that is shared by both reading methods.

That is, the first document reading section R1 for reading and scanning the document placed on the document table glass 121 by moving the image reading sensor 110, and the automatic document feeder (ADF) 2 as the document feeding means. And a second document reading unit R2 for reading and scanning the sheet-like document conveyed to the non-scanning reading glass 122 by keeping the image reading sensor 110 stationary.

FIG. 1 shows a detailed sectional view of the vicinity of the image reading sensor 110.

The image reading sensor 110 is the original platen glass 1
An illumination unit 111 for illuminating an original through the scanning glass 21 and the scanning glass 122, a SELFOC lens 112 for forming an image of reflected light from the original, and an image sensor 113 arranged at the image formation position of the SELFOC lens 112. Have,
These are integrally contained in the casing 114.
The casing 114 is abutted against the original table glass 121 or the flow reading glass 122 via an abutting member (not shown) having high slidability, and the image reading sensor 110 is arranged at a predetermined distance from the original surface. It

The illuminating means 111 is composed of, for example, an LED which is a light emitting source and a light guide, and the LED which is the illuminating means 111 and the light guide are provided on a platen glass in order to prevent the fogging of the white background due to the floating of the original. It is arranged so that the maximum amount of light can be obtained at a predetermined height (H: 1 mm in this embodiment) from the original placement surface on the upper surface 121 or the original passage surface on the upper surface of the scanning glass 122.

An automatic document feeder 2 is attached to the upper part of the image reading device 1 so as to be openable and closable, and functions as a pressure plate for fixing the document on the platen glass 121 in the book reading system.

In the case of the book reading method, the platen glass 12
The document placed on the sheet 1 is fixed by the automatic document feeder 2 and the document is read while the image reading sensor 110 is driven in the sub-scanning direction at a predetermined speed.

In the case of the flow reading method, the image reading sensor 11
0 is fixed below the flow-reading glass 122, and the automatic document feeder 2 reads a document conveyed on the flow-reading glass 122 in the sub-scanning direction at a predetermined speed.

The automatic document feeder 2 of the second document reading section R2 shown in FIG.
22. Platen roller 201 for suppressing floating from 22.
Is equipped with.

In the image reading apparatus of this embodiment,
The platen roller 201 of the automatic document feeder 2 is arranged within the reading range of the image reading sensor 110 in the main scanning direction with a predetermined distance from the flow reading glass 122 at the time of flow reading to regulate the floating of the document. It is characterized by having a first outer diameter portion 201A to be conveyed and a second outer diameter portion 201B smaller than the first outer diameter portion 201B. The vicinity of the platen roller 201 is scanned by the image reading sensor 110, and the second outer diameter portion 201B is conveyed.
The roller center position is detected from the peak of the brightness level on the roller surface.

In the second outer diameter portion 201B, in the flow reading method, the portion immediately below the center of the roller on the roller surface is the illuminating means 1.
It is set so as to be the position of the maximum light amount of 11. Therefore, in the longitudinal direction of the roller, the second outer diameter portion 201B
Is used to detect the roller center position, the image reading sensor 11
The brightness level of the roller surface detected by 0 peaks just below the center of the roller. Therefore, the image reading sensor 1
It is possible to position the 10 at the optimum reading position in the flow-reading method with high accuracy based on the center position of the roller, and it is possible to read a high-quality image in the flow-reading method.

In particular, the height of the maximum light amount position of the illumination means 111 of the image reading sensor 110 from the document passage surface or the document placing surface is H, and the outer diameter of the first outer diameter portion 201A of the platen roller 201 is D1, If the outer diameter of the second outer diameter portion 201B is D2, and the distance between the roller surface of the first outer diameter portion 201A and the document passage surface of the flow reading glass 122 is C, then H = C + (D1-D2) / It is set to the relationship of 2.

Specifically, this platen roller 201
As shown in FIG. 3, most of the longitudinal direction is the first outer diameter portion 201A (D1 = φ20 mm in the present embodiment), and both end portions are the second outer diameter portion 201B (main portion). In the embodiment, D2 = φ18.4 mm). Further, the length of the first outer diameter portion 201A in the longitudinal direction is
The effective width in the main scanning direction of the platen glass 121 is wider than the width in the main scanning direction of the document size that can be conveyed by the automatic document conveying device 2. In addition, the image reading sensor 1
The readable range of 10 in the main scanning direction is a range including the lengths of the second outer diameter portions 201B at both ends in addition to the first outer diameter portion 201A of the platen roller 201. Further, the effective width of the flow reading glass 122 in the main scanning direction includes the entire readable range of the image reading sensor 110 in the main scanning direction.

In the flow-reading method, that is, when the automatic document feeder 2 is closed, the platen roller 201 is located on the upper surface of the flow-reading glass 122 and has a first outer diameter portion 201.
A is a predetermined interval (in the present embodiment, C = 0.2 mm)
Are separated from each other. At this time, the second outer diameter portion 201B
Are placed 1 mm apart from the upper surface of the flow reading glass 122.

When the original is read by the flow-reading method, first, the operation of detecting the center of the platen roller 201 is performed. The image reading sensor 110 is driven in the sub-scanning direction in the vicinity of the platen roller 201 while illuminating the platen roller 201 by the illumination means 111, and the platen roller 2
01, the luminance level of the second outer diameter portion 201B is measured. At this time, the roller surface of the second outer diameter portion 201B is measured since the position directly below the center of the roller is 1 mm above the upper surface of the flow reading glass 122, which is the position where the maximum light amount of illumination is obtained. The brightness level peaks when the reading position is directly below the center of the roller.
As a result, the center position of the platen roller 201 is detected, and the image reading sensor 110 is positioned 0.5 mm upstream of the roller center where optimum reading conditions are obtained.

The originals stacked on the paper feed tray 205 of the automatic document feeder 2 are fed by the paper feed roller 202,
The platen roller 2 is moved at a predetermined speed by the conveying roller 203.
It is transported below 01. The original is scanned by a platen roller 201 which rotates at a predetermined number of rotations, and a reading glass 122 is used.
The amount of floating from the upper surface is limited, and the image reading sensor 110
Reads the image by illuminating the document conveyed between the platen roller 201 and the upper surface of the scanning glass 122 by the illumination unit 111. The document that has passed through the platen roller 201 is guided to the conveyance roller 204 by the jump table 123 and is discharged to the paper discharge tray 206.

At this time, since the image reading sensor 110 is positioned at the optimum reading position with reference to the center position of the platen roller 201, the effect of defocusing due to floating of the document and dust attached to the flow reading glass 122. The high-quality image is read without receiving the image.

Further, the limitation of the document feeding and floating in the flow-reading section is all performed by the portion of the first outer diameter portion 201A, and the portions of the second outer diameter portion 201B at both ends of the platen roller pass the document. Since it is out of the range, it does not have any adverse effect on the conveyance of the document.

[0040]

As described above, according to the first and second aspects of the present invention, the platen roller is provided with the first outer diameter portion that limits the floating of the document within the reading range of the reading means. And a second outer diameter portion set at the maximum light amount position of the illumination means, the vicinity of the platen roller is scanned by the reading means, and the roller center position from the peak of the brightness level on the roller surface of the second outer diameter portion. Since it is configured to detect, the image reading position in the flow-reading method can be positioned with high precision based on the platen roller center.

Therefore, out-of-focus due to the floating of the document is prevented, and high-quality images can be read without being affected by dust attached to the flow reading glass.

Further, according to the invention described in claim 3,
Since the second outer diameter portion of the platen roller is set outside the document passage area, it does not have any adverse effect on the document transportation.

[Brief description of drawings]

FIG. 1 is a sectional view showing details of a flow reading unit of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an overall configuration of an image reading apparatus according to an embodiment of the present invention.

FIG. 3 is a perspective view showing configurations of a platen roller and an image reading sensor according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing an overall configuration of an image reading apparatus including a conventional automatic document feeder.

5 is a cross-sectional view showing details of a flow reading unit of the apparatus of FIG.

[Explanation of symbols]

R1 First original reading section R2 Second original reading section 1 Image reading device 110 Image reading sensor (reading means) 111 Lighting means 112 SELFOC lens 113 image sensor 114 casing 121 Platen glass (first transparent member) 122 Scanning reading glass (second light transmitting member) 123 Jump stand 2 Automatic document feeder (ADF) 201 Platen roller 201A First outer diameter portion 201B second outer diameter portion 202 paper feed roller 203 Conveyor roller 204 Conveyor roller 205 paper tray 206 Output tray

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/107 F term (reference) 2H076 AA58 BA02 BA06 BA24 BB10 2H108 AA14 AA19 CB01 JA00 5C062 AA02 AA05 AB02 AB17 AB30 AB32 AB33 AC66 AD02 AD06 BA00 5C072 AA01 BA04 BA15 CA02 CA14 LA02 LA08 LA18 NA01 RA01 XA01

Claims (3)

[Claims] 1. A first original reading unit for moving and scanning an original placed on a first transparent member, and a first original reading unit for feeding and scanning the original to a second transparent member. A second original reading unit that reads and scans an incoming sheet-shaped original with the reading unit stationary, and the second original reading unit floats the original from the second light-transmissive member at the reading position. The reading means has an illuminating means for illuminating the original through the first and second light transmitting members, and the quantity of light by the illuminating means is the first and second light transmitting means. In an image reading apparatus configured to take a maximum light amount at a position higher than a document passage surface and a document placement surface of a member, the platen roller is within a reading range of the reading unit,
The first outer diameter portion for limiting the floating of the original document and the second outer diameter portion set at the maximum light amount position of the illumination means are provided, and the vicinity of the platen roller is scanned by the reading means. 2. An image reading apparatus having a structure in which the roller center position is detected from the peak of the brightness level on the roller surface of the outer diameter portion of 2. 2. The height of the maximum light amount position of the illuminating means of the reading means from the original passage surface or the original placing surface is H, the outer diameter of the first outer diameter portion of the platen roller is D1, and the second outer diameter portion is D1. If the outer diameter of the outer diameter portion is D2, and the distance between the roller surface of the first outer diameter portion and the document passage surface of the second light transmitting member is C, then the relation of H = C + (D1-D2) / 2 The image reading apparatus according to claim 1, wherein the image reading apparatus is set to. 3. The platen roller second outer diameter portion is set outside the original document passage area.
The image reading apparatus described in 1.