JP2001077976A - Image reader and image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader and an image-forming apparatus that have a processing capability, equivalent to that in a continuous one side reading even in a continuous double side reading. SOLUTION: This image reader is provided with carrier rollers 5, 6, 7 that carry an original 2 along an original carrying path, a read optical section 11 that is illuminated by a lighting lamp 12, has a CCD sensor 16 at an image- forming section forming an image of a reflected light of a 1st side of the original 2 passing through a read section 10a, and uses the CCD sensor 16 to read image information of the 1st side of the original 2, and a read optical section 18 that is illuminated by a lighting lamp 19, uses an image-forming section to once form the image of a reflected light of a 2nd side of the original 2 passing through a read section 10b by the read section 10a and uses the CCD sensor 16 to read image information of the 2nd side of the original 2.

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 an image of a document, such as a scanner, a copying machine, a printer, or a facsimile apparatus, and an image forming apparatus provided with the image reading apparatus.

[0002]

2. Description of the Related Art FIG. 4 is a schematic sectional view of a conventional image reading apparatus. Hereinafter, the related art will be described with reference to the drawings.

[0003] First, the one-sided image reading will be described. A document 102 placed on a document tray 101 of the image reading apparatus is conveyed by a paper feed roller 103, separated and conveyed by a separation roller pair 104, and
05, 106, 107, 108 forward conveyance
It passes through the reading unit 110.

Then, the paper is discharged to the paper discharge tray 120 by the paper discharge roller pair 109. As a result, the order of stacking the originals is maintained.

[0005] The original is illuminated by an illumination lamp 112 and a reflection shade 113 arranged in a reading optical unit 111 when passing through a reading unit 110, and an image is reflected by a first mirror 114, condensed by a lens 115, and read by a reading element. An image is formed by the CCD sensor 116 as a.

[0006] The above operation is repeated for the next original to continuously read an image. The original reading speed is the same as the original conveying speed, and is 220 mm.
/ S is read.

Next, reading of a double-sided image will be described. A document 102 placed on a document tray 101 of the image reading apparatus is conveyed by a feed roller 103, separated and conveyed by a separation roller pair 104, and conveyed by a conveyance roller pair 10.
The paper is conveyed forward by 5, 106, 107 and 108 and passes through the reading unit 110.

Then, the sheet is guided to the reversing path 119 by the flapper 117, re-conveyed again by the pair of reversing conveyance rollers 118 by the pair of conveyance rollers 105, 106, 107 and 108, and passes through the reading unit 110. At this time, the document 102 is guided to a double-sided path 122 by the double-sided flapper 121.

Further, the original 102 is conveyed forward by the pair of conveying rollers 105, 106, 107 and 108 after the completion of the double-side reading, and the reversing path 11 is fed by the flapper 117.
It is led to 9. Then, the pair of transport rollers 105, 106, 107, and 108 are again generated by the pair of reverse transport rollers 118.
After the rear end of the document has passed through the reversing path, the original is conveyed forward by a pair of conveying rollers 105, 106, 107, and 108, and is discharged to the discharge tray 120 by a pair of discharge rollers 109. As a result, the order of stacking the originals is maintained.

The original is illuminated by an illumination lamp 112 and a reflection shade 113 disposed in a reading optical unit 111 when passing through a reading unit 110, and an image is reflected by a first mirror 114, condensed by a lens 115, and read by a reading element. An image is formed by the CCD sensor 116 as a. Also, the original reading speed is the same as the original transport speed.
Reading is performed at 20 mm / s.

[0011]

In the conventional image reading apparatus as described above, it is possible to shorten the sheet interval during continuous one-side reading. This is because it is only necessary to secure a distance that allows variations in the accuracy of the transport position.

Therefore, the reading speed is 220 mm /
Since an A4 document having a document size of 210 mm is transported at a sheet interval of 10 mm in s, 60 documents can be read in one minute. (220mm / s × 60s) / (210mm + 10m)
m) = 60 sheets / min When this is converted into the number of A4 document pages, one page of image information can be obtained from one document, and thus 60 pages / min.

However, during continuous double-side reading, it is necessary to increase the substantial sheet interval. That is, when the both sides are reversed, the reversal path length needs to be 210 mm in original size. Also,
At least 210 mm is required for the trailing edge of the document to pass through the reverse path.

Therefore, in order to increase the space between the next original and the paper by 10 mm, the next original requires a substantial paper interval that allows the previous original to be conveyed by 210 mm + 210 mm + 10 mm = 430 mm.

Therefore, the reading speed is 220 mm /
A4 document with document size 210 mm in s
m, it is possible to read 20 originals per minute. (220mm / s × 60s) / (210mm + 430m)
m) = 20 sheets / min When this is converted into the number of A4 original pages, the number of pages becomes 40 pages / min because two pages of image information can be obtained from one original page.

This means that the processing capability at the time of double-sided reading is inferior to that at the time of single-sided reading by about 34%, and it cannot sufficiently satisfy the user's demand for high productivity for image reading. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide the same processing capability even in continuous double-sided reading as compared with the processing capability in continuous single-sided reading. It is an object of the present invention to provide an image reading apparatus and an image forming apparatus having the same.

[0018]

In order to achieve the above object, in an image reading apparatus according to the present invention, a document transport means for transporting a document along a document transport path, and a first light source, are illuminated by a first light source. An image forming unit that forms reflected light on one surface of the document that is conveyed by the document conveying unit and passes through the first reading unit has an optical information reading element, and the optical information reading element causes one of the documents to be conveyed. A first scanning optical unit for reading the image information of the surface, and a reflected light of the other surface of the document which is illuminated by the second light source and conveyed by the document conveying means and passes through the second reading unit, A second scanning optical unit that forms an image once in the reading unit, forms an image in the image forming unit, and reads image information on the other surface of the document by the optical information reading element. I do.

The length between the first and second reading units is set to at least the maximum length in the transport direction of the original that can be transported by the original transport unit, and the length in consideration of variations during transport. It is also preferred that the length be added.

A third reading unit provided between the first and second reading units, and the other one of the originals illuminated by a third light source and conveyed by the original conveying means and passing through the third reading unit A third scanning in which the reflected light of the surface is once imaged by the first reading unit, then imaged by the imaging unit, and the optical information reading element reads the image information of the other surface of the document. An optical unit, wherein the length between the first and third reading units is a length obtained by adding a length in the conveyance direction of a document of a predetermined size in consideration of dispersion during conveyance. It is also suitable.

Document detecting means for detecting the size of the document to be conveyed, and, based on the detection result of the document detecting means, the document detected by the document detecting means is conveyed to the second or third reading section. It is also preferable to include control means for controlling the document transport means.

Turning means for turning a first reflection plate which is illuminated by the third light source and guides the reflected light of the other surface of the document to the image forming portion; and the control means comprises: the document detection means When it is detected that the document to be conveyed exceeds a predetermined size according to the detection result of (2), the first reflection plate is rotated by the rotation means, thereby the second and third It is also preferable that the optical paths of the reflected light after the first reflection plate of the scanning optical unit are matched.

A document detecting means for detecting the size of the document to be conveyed, and at least the maximum length of the document which can be conveyed by the document conveying means between the first and second reading units in the conveying direction. A first document conveyance path having a length obtained by adding a length in consideration of a variation at the time of conveyance, and a length obtained by adding a length in a conveyance direction of a document having a predetermined size in consideration of a variation at the time of conveyance. A second document transport path, and guides the document detected by the document detection means to the first or second document transport path in accordance with the detection result of the document detection means. It is also preferable to provide switching means.

When the document conveyed by the document detecting means is detected to be smaller than a predetermined size, the switching means guides the document to the second document conveying path and is conveyed by the document detecting means. When it is detected that the original to be read exceeds a predetermined size, it is also preferable to guide the original to the first original transport path.

It is also preferable that the first scanning optical section and the second or third scanning optical section are provided so as to be opposed to each other with the document conveying path interposed therebetween.

An image forming apparatus includes the above-described image reading apparatus and image forming means for recording image information read by the image reading apparatus on a recording material.

[0027]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, the shape, and the relative arrangement thereof should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions, and are not intended to limit the scope of the invention to the following embodiments.

(First Embodiment) FIG. 1 is a schematic sectional view of an image reading apparatus according to a first embodiment of the present invention.

A document 2 placed on a document tray 1 of the image reading apparatus is conveyed by a paper feed roller 3, separated and conveyed by a separation roller pair 4, and forwarded by conveyance roller pairs 5, 6, and 7 as a document conveying means. The reading unit 1 is transported and conveyed, and serves as a first reading unit on the first side as one side of the document
0a and a reading section 10b as a second reading section on the second side as the other side of the document.

Each reading unit uses a transparent conveyance guide, and is configured so that the optical path is not obstructed.
Then, the paper is discharged onto the paper discharge tray 17 by the paper discharge roller pair 9. As a result, the order of stacking the originals is maintained.

In the case of single-sided reading, when the original 2 passes through the first-side reading unit 10a, the illumination lamp 12 as the first light source disposed on the first-side reading optical unit 11 as the first scanning optical unit. The image is reflected by the third mirror 14, condensed by the first lens 15, and reflected by the reflection mirror 13.
An image is formed by the CD sensor 16.

Image reading is continuously performed on the next original by repeating the above operation. The original reading speed is the same as the original conveying speed, and is 220 mm.
/ S is read. Thus, at the time of continuous one-sided reading, the reading speed is 220 mm / s and the document size is 2 mm.
Since a 10 mm A4 document is transported at a sheet interval of 10 mm (document transport variation Y = 10 mm), 60 documents can be read in one minute. (220mm / s × 60s) / (210mm + 10m)
m) = 60 sheets / min When this is converted into the number of A4 document pages, one page of image information can be obtained from one document, and thus 60 pages / min.

In the case of reading a double-sided image, an original is illuminated by an illumination lamp 12 and a reflection shade 13 arranged on a first-side reading optical unit 11 while a document passes through a first-side reading unit 10a. The light is reflected by the third mirror 14, condensed by the first lens 15, and imaged by the CCD sensor 16.

Subsequently, the original is read by the reading unit 10b on the second side.
Is passed through, the illumination light 19 and the reflection shade 20 as the second light source arranged in the reading optical unit 18 on the second surface as the second scanning optical unit, and the image is reflected by the first mirror 21. The light is condensed by the second lens 22, reflected by the second mirror 23, and temporarily formed on the image reading unit 10a on the first surface.

Further, the enlarged image is reflected by the third mirror 14, condensed by the first lens 15, and
An image is formed by the CD sensor 16.

The transport distance from the reading unit 10a on the first side to the reading unit 10b on the second side is L = X + Y = 220 mm (the document size X of A4 document is X = 21).
(0 mm, variation in document conveyance Y = 10 mm). Here, X is the maximum length of a document that can be transported by the document transport unit in the transport direction, and the present embodiment is described using an A4 size document.

The document is read at a document reading speed of 220 mm / s, which is the same as the document conveying speed. Thus, during continuous double-sided reading, after the leading end of the previous document has been conveyed 230 mm through the second-side reading unit 10b, reading of the next document is started by the first-side reading unit 10a. are doing.

This is because the interval between the papers is set to (conveyance distance between reading units 220 mm) + (conveyance variation 10 mm) so that the subsequent document does not block the optical path when reading the second side.
= 230 mm.

Thus, when reading a double-sided document, the reading speed is 220 mm / s and the size of the A4
Since the document is conveyed with a sheet interval of 230 mm, it is possible to read 30 documents per minute. (220mm / s × 60s) / (210mm + 230m
m) = 30 sheets / min. When this is converted into the number of A4 original pages, 60 pages / min because two pages of image information can be obtained from one original page.

This means that the processing capability at the time of double-sided reading is equivalent to the processing capability at the time of single-sided reading, so that the user's demand for high productivity in image reading can be sufficiently satisfied.

(Embodiment 2) FIG. 2 is a schematic sectional view of an image reading apparatus according to a second embodiment of the present invention. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The small-size original 2a and the large-size original 2b placed on the original tray 1 of the image reading apparatus are conveyed by the paper feed roller 3, separated and conveyed by the separation roller pair 4, and conveyed by the conveyance roller pairs 5, 6, 7 The first-side reading unit 10a and the second-side reading unit 10 of the small-size document 2a as a third reading unit
c and the reading unit 10b for the second side of the large-size original 2b
Pass through.

Each reading unit uses a transparent conveyance guide, and is configured so that the optical path is not obstructed. Then, the paper is discharged onto the paper discharge tray 17 by the paper discharge roller pair 9.

Thus, the order of stacking the originals is maintained. The small size document described in the present embodiment is A4 as a predetermined size defined by the JIS standard.
This means a document of a size equal to or smaller than the size, and a large-size document is A4 as a predetermined size defined by the JIS standard.
This means a manuscript that exceeds the size.
Documents are classified into four size documents.

The document size is detected by measuring the document passage time by a document size detection sensor 31 provided immediately after the pair of separation rollers and serving as a document detection means. The timing for feeding the next sheet is determined by the means.

In the case of single-sided reading, when the document passes through the first-side reading unit 10a, the first-side reading optical unit 1
The image is illuminated by the illumination lamp 12 and the reflection shade 13 disposed on the first mirror 1, and the image is reflected by the third mirror 14.
The light is condensed by the lens 15 and is imaged by the CCD sensor 16.

Image reading is continuously performed on the next original by repeating the above operation. The document reading speed is the same as the document conveying speed, and is 220 mm /
Reading is performed at s. As a result, at the time of continuous single-sided reading of the small size document 2a, the reading speed is 2
A4 document with a document size of 210 mm at 20 mm / s
0 mm (Small size document conveyance variation Y = 10 m
m), it is possible to read 60 originals per minute. (220mm / s × 60s) / (210mm + 10m)
m) = 60 sheets / min When this is converted into the number of A4 document pages, one page of image information can be obtained from one document, and thus 60 pages / min.

In continuous single-sided reading of the large-size original 2b, the reading speed is 220 mm / s, and an A3 original having an original size of 420 mm is conveyed at a sheet interval of 20 mm (large-size original conveyance variation = 20 mm). It is possible to read 30 originals. (220mm / s × 60s) / (420mm + 20m
m) = 30 sheets / min. When this is converted into the number of A4 original pages, 60 pages / min because two pages of image information can be obtained from one original page.

On the other hand, in the case of reading a double-sided image, the means for reading the second side is different between the small-size original 2a and the large-size original 2b.

First, in the case of reading a double-sided image of the small-size original 2a, the original is read by the reading unit 10a on the first side.
The light is illuminated by an illumination lamp 12 and a reflection shade 13 arranged in a reading optical unit 11 on the first surface while passing through the image, an image is reflected by a third mirror 14, condensed by a first lens 15, and It is imaged.

Subsequently, while the document is passing through the reading unit 10c for the second surface of the small-size document 2a, the illumination as the third light source disposed on the reading optical unit 24 for the second surface as the third scanning optical unit. The image is illuminated by the lamp 25 and the reflection shade 26, and the image is reflected by the fourth mirror 27 as the first reflection plate of the small-size document 2 a, condensed by the second lens 22, reflected by the second mirror 23, The image is temporarily formed on the image reading unit 10a on the first surface.

Further, the enlarged image is reflected by the third mirror 14, collected by the first lens 15, and
An image is formed by the CD sensor 16.

The transport distance from the reading unit 10a on the first side to the reading unit 10c on the second side of the small size document 2a is L = X + Y = 220 mm (the document size X of the A4 document is X = 21).
0 mm, small size document conveyance variation Y = 10 m
m) It is configured at a remote location.

The document is read at the same document reading speed of 220 mm / s as the document conveying speed.

As a result, during continuous double-sided reading of the small-size original 2a, the leading end of the previous original passes through the reading unit 10c for the second side of the small-size original 2a, and the reading of the small-size original 2a continues.
After the document is conveyed by mm, the reading of the next document is started by the reading unit 10a on the first side.

This is because the distance between the sheets is set to ((conveyance distance between reading units: 220 mm) + (small size document conveyance variation: 10 mm) = 230 mm) so that the subsequent document does not block the optical path when reading the second side. .

Thus, during continuous double-sided reading of the small-size original 2a, an A4 original having an original size of 210 mm is transported at a reading speed of 220 mm / s at a sheet interval of 230 mm, so that 30 originals can be read in one minute. It is possible. (220mm / s × 60s) / (210mm + 230m
m) = 30 sheets / min. When this is converted into the number of A4 original pages, 60 pages / min because two pages of image information can be obtained from one original page.

Next, the case of reading a double-sided image of the large size original 2b will be described.

The original is illuminated by the illumination lamp 12 and the reflection shade 13 arranged on the first-side reading optical unit 11 while passing through the first-side reading unit 10a, and the image is reflected by the third mirror 14 so as to be reflected by the first mirror. The light is condensed by the lens 15 and is imaged by the CCD sensor 16.

Subsequently, while the original is passing through the reading unit 10b for the second side of the large-size original 2b, the original is illuminated by the illumination lamp 19 and the reflection shade 20 arranged on the reading optical unit 18 for the second side, and the image is enlarged to a large size. The original is reflected by the first mirror 21, condensed by the third lens 28, and is once formed on the image forming position 29 of the second lens 22.

At this time, when the large size original 2b is detected by the original size detection sensor 31, the control means (not shown) is constituted by the solenoid 30 serving as a rotating means with the fourth mirror 27 of the reading optical unit 24 as a rotating means. The mirror rotating means is retracted to a position where the optical path for reading the large-size original 2b is not interrupted.

Therefore, the further enlarged image is the second image.
The light is condensed by the lens 22, and is reflected by the second mirror 23 to form an image once on the image reading unit 10a on the first surface.

Further, the enlarged image is reflected by the third mirror 14, condensed by the first lens 15,
An image is formed by the CD sensor 16.

The transport distance from the reading unit 10a on the first side to the reading unit 10b on the second side of the large-size original 2b is L = 2X + 2Y = 440 mm (the original size 2X = 420 mm of the A3 original, the large-size original conveyance variation 2Y).
= 20 mm) away from each other.

The document is read at a document reading speed of 220 mm / s, which is the same as the document conveying speed.

Thus, during continuous double-sided reading of the large-size original 2b, after the leading end of the previous original has been conveyed 460 mm through the second-side reading unit 10b of the large-size original, the first-side reading unit 10a returns The reading of the next document is started.

The reason for this is that the paper interval is set to ((transport distance between reading sections: 440 mm) + (large-size original transport variation: 20 mm) = 460 mm) so that the subsequent original does not block the optical path when reading the second side. is there.

Thus, during continuous double-sided reading of the large-size original 2b, an A3 original having an original size of 420 mm is transported at a reading speed of 220 mm / s at a sheet interval of 460 mm, so that 15 originals can be read in one minute. It is possible. (220mm / s × 60s) / (420mm + 460m)
m) = 15 sheets / minute When this is converted into the number of A4 original pages, the image information is 60 pages / minute because four pages of image information can be obtained from one original page.

This means that the processing capability for double-sided reading is equal to the processing capability for single-sided reading. Also, it means that the processing capacity at the time of reading the large size document 2b is equal to the processing capacity at the time of reading the small size document 2a. Therefore, it is possible to sufficiently satisfy a user's demand for high productivity for image reading.

When the small-size original 2a and the large-size original 2b are mixed, the original size is detected by the original-size detecting sensor 31, and the paper feeding timing and the optical reading unit 24 for reading the small-size original 2a are controlled by control means (not shown). Is controlled when the fourth mirror 27 is retracted. As a result, the requirement for high productivity can be sufficiently satisfied even when different sizes are mixed.

(Embodiment 3) FIG. 3 is a schematic sectional view of an image reading apparatus according to a third embodiment of the present invention. Note that the same components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.

The small-size original 2a and the large-size original 2b placed on the original tray 1 of the image reading apparatus are transported by the paper feed roller 3, separated and transported by the separation roller pair 4, and transported by the transport roller pairs 5, 6, and 7. , And passes through the reading unit 10a on the first surface and the reading unit 10b on the second surface.

Each reading unit uses a transparent conveyance guide, and is configured so that the optical path is not blocked. Then, the paper is discharged onto the paper discharge tray 17 by the paper discharge roller pair 9. As a result, the order of stacking the originals is maintained.

The small size document described in the present embodiment means a document of A4 size or less specified by the JIS standard, and the large size document exceeds the A4 size specified by the JIS standard. Means the manuscript,
In the case of overseas paper, the document is classified into A4 size originals.

The detection of the document size is performed by the separation roller pair 4.
The original size is detected by measuring the original passage time by the original size detection sensor 31 provided immediately after the above, and the sheet feeding timing of the next sheet is determined by control means (not shown).

In the case of single-sided reading, when the original passes through the first-side reading unit 10a, the first-side reading optical unit 1
The image is illuminated by the illumination lamp 12 and the reflection shade 13 disposed on the first mirror 1, and the image is reflected by the third mirror 14.
The light is condensed by the lens 15 and is imaged by the CCD sensor 16.

Image reading is continuously performed on the next original by repeating the above operation. The document reading speed is the same as the document conveying speed, and is 220 mm /
Reading is performed at s.

Thus, during continuous single-sided reading of the small-sized document 2a, an A4 document having a reading speed of 220 mm / s and a document size of 210 mm is transported at a sheet interval of 10 mm (small-size document transport variation Y = 10 mm). It is possible to read 60 originals per minute. (220mm / s × 60s) / (210mm + 10m)
m) = 60 sheets / min When this is converted into the number of A4 document pages, one page of image information can be obtained from one document, and thus 60 pages / min.

In continuous single-sided reading of the large-size original 2b, the reading speed is 220 mm / s, and an A3 original having an original size of 420 mm is transported at a sheet interval of 20 mm (large-size original transport variation = 20 mm), so that it takes one minute. It is possible to read 30 originals. (220mm / s × 60s) / (420mm + 20m
m) = 30 sheets / min. When this is converted into the number of A4 original pages, 60 pages / min because two pages of image information can be obtained from one original page.

On the other hand, in the case of reading a double-sided image, the means for reading the two sides differs between the small-size original 2a and the large-size original 2b.

First, in the case of reading a double-sided image of the small size original 2a, the original is read by the reading unit 10a on the first side.
The light is illuminated by an illumination lamp 12 and a reflection shade 13 arranged in a reading optical unit 11 on the first surface while passing through the image, an image is reflected by a third mirror 14, condensed by a first lens 15, and It is imaged.

Subsequently, while the document guided to the second document conveying path is passing through the second-side reading section 10b by the double-sided flapper 32 as a switching means, the illumination arranged on the second-side reading optical section 18 is performed. The image is illuminated by the lamp 19 and the reflection shade 20, and the image is reflected by the first mirror 21 of the small-size document, collected by the second lens 22, reflected by the second mirror 23, and transmitted to the image reading unit 10 a on the first surface. Once formed.

Further, the enlarged image is reflected by the third mirror 14, condensed by the first lens 15,
An image is formed by the CD sensor 16. First-side reading unit 10
a = L + X + Y = 220 mm (document size of A4 document X = 21
0 mm, small size document conveyance variation Y = 10 m
m) It is configured at a remote location.

The original is read at the original reading speed of 220 mm / s, which is the same as the original conveying speed. Thus, during continuous double-sided reading of the small-size original 2a, after the leading end of the previous original has been conveyed 230 mm after passing through the second-side reading unit 10b of the small-size original 2a, the first-side reading unit 10a reads the next original. The reading of the document is configured to start.

The reason is that the interval between the sheets is set to (220 mm of the transport distance between the reading units) + (10 mm of the variation in the transport of the small-size document) = 230 mm so that the subsequent document does not block the optical path when reading the second side. .

Thus, during continuous double-sided reading of the small-size original 2a, an A4 original having an original size of 210 mm is transported at a reading speed of 220 mm / s at a sheet interval of 230 mm, so that 30 originals can be read in one minute. It is possible. (220mm / s × 60s) / (210mm + 230m
m) = 30 sheets / min. When this is converted into the number of A4 original pages, 60 pages / min because two pages of image information can be obtained from one original page.

Next, the case of reading a double-sided image of the large-size original 2b will be described. The first-side reading optical section 11a while the original passes through the first-side reading section 10a.
The image is illuminated by the illumination lamp 12 and the reflection shade 13 arranged in the camera, the image is reflected by the third mirror 14, collected by the first lens 15, and formed into an image by the CCD sensor 16.

On the other hand, the original is guided to a large-size original double-sided conveyance path 33 as a first original conveyance path by a double-sided flapper 32 as switching means.
The sheet is conveyed to the reading unit 10b on the second side by 6, 7, and 8.

While passing through the reading unit 10b for the second surface, the image is illuminated by the illumination lamp 19 and the reflection shade 20 arranged on the reading optical unit 18 for the second surface, and the image is reflected by the first mirror 21 of the large-size document. The image is condensed by the second lens 22 and the image reading unit 1 on the first surface
The image is once formed at 0a.

Further, the enlarged image is reflected by the third mirror 14, condensed by the first lens 15,
An image is formed by the CD sensor 16. First-side reading unit 10
a = 2X + 2Y = 440 mm (document size of A3 document 2X
= 420 mm, large size original conveyance variation 2Y = 2
0 mm).

The original is read at the same reading speed of 220 mm / s as the original conveying speed. As a result, during continuous double-sided reading of the large-size original 2b,
After the leading end of the previous document has been conveyed 460 mm after passing through the second-side reading unit 10b of the large-size document 2b, reading of the next document is started by the first-side reading unit 10a.

The reason for this is that the paper interval is set to (460 mm transport distance between the reading units) + (large-size document transport variation 20 mm) = 460 mm so that the subsequent document does not block the optical path when reading the second side. is there.

Thus, during continuous double-sided reading of a large-size document, an A3 document having a document size of 420 mm is transported at a reading speed of 220 mm / s at a sheet interval of 460 mm, so that 15 documents can be read in one minute. It is. (220mm / s × 60s) / (420mm + 460m)
m) = 15 sheets / minute When this is converted to the number of A4 original pages, the number of A4 original pages is 60 pages / minute since four pages of image information can be obtained from one original page.

This means that the processing capacity for double-sided reading is equal to the processing capacity for single-sided reading. It also means that the processing capacity when reading the large-size original 2b is equal to the processing capacity when reading the small-size original 2a. Therefore, it is possible to sufficiently satisfy the user's demand for high productivity for image reading.

When the small-size original 2a and the large-size original 2b are mixed, the original size is detected by the original-size detecting sensor 31, and the feeding timing is controlled by control means (not shown). Is detected, the document is guided to the large-size document double-sided conveyance path 33 by the double-sided flapper 32. As a result, the requirement for high productivity can be sufficiently satisfied even when different sizes are mixed.

[0096]

As described above, according to the present invention,
Since the optical information reading device includes a first scanning optical unit that reads image information of one surface of the document by using the optical information reading element, and a second scanning optical unit that reads image information of the other surface of the document by using the optical information reading device. , Even during continuous double-sided reading, it is possible to provide a processing capacity equivalent to that of continuous single-sided reading, which can sufficiently satisfy the user's demand for high productivity for image reading and improve the user's work efficiency. Can be improved.

Further, since the first scanning optical section and the second scanning optical section read the image information of the original by the same optical information reading element, the configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an image reading apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of an image reading device according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of a conventional image reading apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 document tray 2 document 3 paper feed roller 4 separation roller pair 5, 6, 7, 8 conveyance roller pair 9 discharge roller pair 10 a, 10 b, 10 c reading unit 11, 18, 24 reading optical unit 12, 19, 25 illumination lamp 13, 20, 26 Reflector shade 14, 21, 23, 27 Mirror 15, 22, 28 Lens 16 CCD sensor 17 Discharge tray 29 Image formation position 30 Solenoid 31 Document size detection sensor 32 Double-sided flapper 33 Large-size document double-sided conveyance path

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H076 AA04 AA58 BA24 BA47 BA58 BA63 BB04 5C051 AA01 BA03 DA03 DB01 DB22 DB24 DB28 DC02 DC04 DC05 DC07 DE02 DE09 FA01 5C072 AA01 BA03 CA02 CA09 DA02 DA04 DA21 DA23 EA05 NA01 RA01 WA02A

Claims (9)

[Claims] 1. A document conveying means for conveying a document along a document conveying path; and a reflection of one surface of the document illuminated by a first light source, conveyed by the document conveying means and passing through a first reading unit. A first scanning optical unit that has an optical information reading element in an image forming unit that forms light, reads image information of one surface of the document by the optical information reading element, and is illuminated by a second light source; After the reflected light of the other surface of the document conveyed by the document conveying means and passing through the second reading unit is once imaged by the first reading unit, the image is formed by the image forming unit to obtain the optical information. A second scanning optical unit for reading image information on the other surface of the document by a reading element. 2. The length between the first and second reading units is:
2. A length which is obtained by adding at least a length in a conveyance direction of a maximum document which can be conveyed by the document conveyance means and a length in consideration of a variation at the time of conveyance.
The image reading device according to claim 1. A third reading section provided between the first and second reading sections; and a document illuminated by a third light source, conveyed by the document conveying means, and passing through the third reading section. After the reflected light of the other surface of the document is once formed by the first reading unit, the image is formed by the image forming unit, and the optical information reading element reads the image information of the other surface of the document. A scanning optical unit, wherein a length between the first and third reading units is a length obtained by adding a length in consideration of a variation at the time of transport to a length in a transport direction of a document of a predetermined size. The image reading device according to claim 1, wherein: 4. A document detecting means for detecting a size of a conveyed document, and a document detected by the document detecting means is sent to the second or third reading unit in accordance with a detection result of the document detecting means. The image reading apparatus according to claim 3, further comprising: a control unit configured to control the document conveyance unit so that the document is conveyed. 5. A rotating device for rotating a first reflector illuminated by the third light source and guiding reflected light from the other surface of the document to the image forming unit, wherein the control unit controls the document. When it is detected that the conveyed document exceeds a predetermined size according to the detection result of the detecting means, the first reflecting plate is rotated by the rotating means, so that the second and the second are reflected. 5. The image reading apparatus according to claim 4, wherein the optical paths of the reflected light after the first reflection plate of the third scanning optical unit coincide with each other. 6. A document detecting means for detecting a size of a document to be conveyed, and at least a length of the largest document in a conveying direction between the first and second reading units, the document being conveyable by the document conveying means. In addition, the length in consideration of the variation at the time of transport is added to the length of the first document transport path, which is a length obtained by adding the length in consideration of the variation at the time of transport, and the length of the document of the predetermined size in the transport direction. And a second document transport path having a length of a second document transport path, wherein the document detected by the document detector is detected by the first or second document transport path according to a detection result of the document detector. The image reading apparatus according to claim 1, further comprising a switching unit that guides the user to the image reading apparatus. 7. When the document conveyed by the document detecting means is detected to be smaller than a predetermined size, the switching means guides the document to the second document conveying path. 7. The image reading apparatus according to claim 6, wherein, when it is detected that the conveyed document exceeds a predetermined size, the document is guided to the first document conveyance path. 8. The apparatus according to claim 1, wherein the first scanning optical section and the second or third scanning optical section are provided so as to face each other with the document conveying path interposed therebetween. 2. The image reading device according to claim 1. 9. An image reading apparatus according to claim 1, further comprising: an image forming unit configured to record image information read by the image reading apparatus on a recording material. Image forming device.