JP2002344702A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can read an image having high accuracy, without being affected by a state of a front side (luster) of an original on read image information, by preventing a regulator reflecting component from the original from mixing in with the image information. SOLUTION: In the image reader where a read means 10 reads image information of an original, while an original carrying means 12 carries the original 20, when the original carrying means and the read means relatively have a read range which deviates from a prescribed position in the carrying direction, the minimum angle of a light lighting the original at an extreme part of the read range in the carrying direction is selected to be greater than twice the angle between a normal of the original with a curvature by the original carrying means and an optical axis of the read means.

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, and more particularly to an image reading apparatus in which image information of a document is read by a reading means such as a line sensor (CCD).

[0002]

2. Description of the Related Art Conventionally, image information of a document is line-scanned in the sub-scanning direction, and the image information is read by a CCD as a reading means.
Various image reading apparatuses have been proposed in which an image is formed on a line sensor such as that described above and an image signal of the document is read using an output signal obtained from the CCD.

FIG. 3 is a schematic view of a main part of a conventional image reading apparatus. FIG. 3 shows an optical system for reading an image using, for example, a flow scan. FIG. 4 is a top view of a main part of the original mounting glass table when the original mounting glass table is viewed from above.

In the image reading apparatus shown in FIG.
Is fixed, and a scanning system (image reading unit) in the image reading apparatus is fixed.
A first scanning device 71 scans the original 50 to read image information of the original 50 and an original automatic feeding device (not shown) (hereinafter, also referred to as “DF”). And a second reading device for reading the image information of the document 80.

The first reading device illuminates an original 50 placed on an original placing glass table 51 with an illumination light source 54, passes image information of the illuminated original 50 through a slit 55, and scans the original. First, second, and third mirrors 56, 57,
An image is formed on a line sensor 60 such as a CCD by an image forming lens 59 through 58, and the image information of the original 50 is read digitally.

In the first reading apparatus, as a method for scanning the image information of the original 50 in the sub-scanning direction, for example, first, second and third mirrors 56, 57 and 58 for scanning are indicated by arrows in the drawing. The movement is performed while maintaining a constant relationship in the direction A (sub-scanning direction). The scanning speed of each scanning mirror at this time is, for example, when the speed of the first mirror 56 is V, the scanning speed of the second and third mirrors 57 and 58 is V.
/ 2.

The second reading device scans the illumination light source 54, the slit 55, the first, second, and third mirrors 56, 57, 58, the imaging lens 59, and the line sensor 60 before reading the original 80. The system 71 moves to the lower part of the original flow reading glass table (original conveyance unit glass) 81. The light source 54,
The slit 55, the first, second, and third mirrors 56, 57,
Only 58 may be moved.

Next, the original 80 is sequentially conveyed from an automatic original feeder (not shown) and illuminates the original 80 with the illumination light source 54 when passing through the upper portion of the original reading glass table 81.
The reflected light flux based on the image information of the illuminated original 80 passes through the slit 55 and passes through the first, second, and third mirrors 56, 57, and 58 for scanning, and is formed by the imaging lens 59 through the CCD.
An image is formed on the surface of the line sensor 60. And manuscript 8
0 is sequentially conveyed and passed over the original flow reading glass table 81. During that time, a signal based on the image information of the original 80 in the sub-scanning direction is obtained, so that the image information of the original 80 is read. .

As described above, by providing a scanning system at the leading end of the image reading apparatus and at the same time providing a simple DF for transporting the original, the original is limited to a sheet-like original, but the original can be automatically read.

[0010]

However, in the above-described image reading apparatus, when the original 80 is conveyed from the automatic original feeder (not shown) onto the original reading glass platen 81, the original is transferred to the original transfer section. Original 80 due to height difference
The document 80 is conveyed in a state where the document 80 has a curvature.

In particular, when the image reading apparatus is configured as shown in FIG. 3, the original 80 is conveyed by the automatic document feeder (not shown) and returns to the automatic document feeder. At this time, the document 80 makes a U-turn in the vicinity of the document flow reading glass table 81. Therefore manuscript 8
Warpage (curvature) was easily attached to zero.

However, this type of image reading apparatus also has a great advantage. For example, when a document is conveyed by the automatic document feeder, makes a U-turn near the document flow reading glass table 81, and returns to the same automatic document feeder again,
Since the original placed in the automatic document feeder returns to the same automatic document feeder, the size of the automatic document feeder and the size of the image reading device can be reduced.

FIG. 5 is an enlarged view of the reading section of the second reading apparatus shown in FIG. 3 when a document is conveyed. In such an image reading apparatus, when the optical axis N of an image forming lens (not shown) as an image forming means is located immediately below the center O of the document conveying roller 82, that is, at the reading position X, normal image reading is performed. However, the optical axis N of the imaging lens is located just below the center O of the document conveying roller 82 due to, for example, a mounting error or a stationary position error when the scanning system is moved in the sub-scanning direction and then returned to the original position. When it is not at the reading position X, that is, when it is shifted from the reading position X by a predetermined amount in the sub-scanning direction (Y direction), the following problems occur.

Next, the above problem will be described with reference to FIG.

FIG. 6 is an enlarged view (document 80 is not shown) in which the reading section at the time of document conveyance shown in FIG. 5 is further enlarged. In the figure, the relative position of reading in the sub-scanning direction (Y direction) between the automatic document feeder (not shown) and the scanning system (not shown) in the image reading device is just below the center O of the document feed roller 82. 3 shows a state where the distance from the reading position X is shifted by Δ in the sub-scanning direction. At this time, the document has a curvature (warp) as shown in FIG. 5 and, due to the curvature, the total reflection component of the illumination light from the illumination light source 54 that is regularly reflected by the document 80 becomes It is likely to be included in the CCD as the reading element, that is, the image information of the document.

For this reason, in a conventional image reading apparatus, for example, when a glossy original is conveyed and read,
The specular reflection component due to the gloss of the original is placed on the image information of the original, and there is a problem that high density such as a black background portion is hardly produced and the image becomes thin. In particular, when trying to reduce the size of the image reading device and the automatic document feeder, the above-described problem is likely to occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus which is small and can read an image with high accuracy.

[0018]

According to a first aspect of the present invention, there is provided an image reading apparatus for reading image information of a document by a reading means while conveying the document by the document conveying means. When the reading means has a certain reading range relatively deviated from the predetermined position in the conveying direction, the minimum angle of the illumination light for illuminating the document at the extreme end of the reading range in the conveying direction is set at the extreme end position. It is characterized in that the angle is larger than twice the angle formed between the normal line of the document curved by the document conveying means and the optical axis of the reading means.

According to a second aspect of the present invention, there is provided an image reading apparatus, comprising: a first reading apparatus for fixing an original and reading image information of the original by using a scanning system; A second reading device for reading information, wherein the second reading device reads image information of the document while transporting the document by the document transport device;
When the document conveying means and the reading means have a certain reading range which is relatively deviated from a predetermined position in the conveying direction, the minimum angle of the illumination light for illuminating the document is set at the end of the reading range in the conveying direction. The document is characterized in that it is larger than twice the angle formed between the normal line of the original document at the extreme end position where the original document is curved by the original conveying means and the optical axis of the reading means.

According to a third aspect of the present invention, there is provided an image reading apparatus comprising: conveying means for conveying a document on a document flow reading table using a document conveying roller; and illuminating means for illuminating the document from a side opposite to the document conveying roller. And an image forming means for forming image information of the document illuminated with the light beam from the illuminating means on the surface of the reading means, the optical axis N of the image forming means and the illuminating means When the minimum angle among the angles formed by the luminous flux from is γ (degrees), 23 ° <γ <30 °.

[0021] The invention according to claim 4 characterized in that in the invention of claim 3, the optical axis N of the imaging means, the angle between the normal line L at the intersection A ₀ of the original conveying roller and the optical axis N theta (Every time)
Where θ ≦ 11.5 °.

According to a fifth aspect of the present invention, there is provided an image reading apparatus comprising: a first reading apparatus for fixing an original and reading image information of the original using a scanning system; and an image reading apparatus for conveying and sequentially sending the original. A second reading device for reading information, the second reading device comprising: conveyance means for conveying the document on a document flow reading table using document conveyance rollers; Illuminating means for illuminating from the side opposite to the document conveying roller, and image forming means for forming image information of the document illuminated by a light beam from the illuminating means on a reading means surface, When the minimum angle among the angles formed by the optical axis N of the means and the luminous flux from the illumination means is γ (degrees), 23 ° <γ <30 °.

The invention of claim 6 is the invention of claim 5, the optical axis N of the imaging means, the angle between the normal line L at the intersection A ₀ of the original conveying roller and the optical axis N theta (Every time)
Where θ ≦ 11.5 °.

[0024]

[First Embodiment] FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. FIG. 1 shows an optical system when an image is read using, for example, a flow scan. . FIG. 2 is an enlarged view in which the reading unit at the time of document conveyance shown in FIG. 1 is enlarged.

In FIG. 1, reference numeral 1 denotes an original placing table (original placing glass table) on which an original 30 is placed. Reference numeral 2 denotes a front original abutting nameplate, 3 denotes a shading plate, 4 denotes an illuminating light source as an illuminating means, and is composed of a fluorescent tube such as a xenon lamp. Reference numeral 15 denotes a reflection plate which reflects a light beam, which is not directly directed to the reading position of the document, out of the light beams emitted from the illumination light source 4 and condenses the light efficiently on the document surface. Reference numeral 5 denotes a slit that is long in the main scanning direction and blocks stray light from the document surface. 6, 7, 8 are the first for scanning,
The second and third mirrors guide a light beam based on image information from the document surface to an imaging lens 9 described later. Reference numeral 9 denotes an image forming lens as image forming means, which reduces image information of a document at a fixed magnification and forms an image on a line sensor 10 described later. Reference numeral 10 denotes a line sensor (CCD) as a reading unit, in which a plurality of reading elements are arranged in the main scanning direction. Each element such as the illumination light source 4, the slit 5, the first, second, and third mirrors 6, 7, and 8 for scanning, the imaging lens 9, and the line sensor 10 is a scanning system (image reading unit) 21. Constitutes one element.

Reference numeral 11 denotes a document flow reading table (document flow reading glass table), which is arranged at a position off the document placing glass table 1 in the sub-scanning direction. Reference numeral 12 denotes a document transport roller which constitutes one element of the transport means (document transport means), and transports the document 20 sequentially from an automatic document feeder (not shown).

In the present embodiment, when performing normal image reading, the original 30 placed on the original placing glass table 1 is illuminated by the illumination light source 4 and based on image information from the illuminated original 30. The light flux passes through the slit 5 and forms an image on the surface of the line sensor 10 by the imaging lens 9 via the first, second and third mirrors 6, 7, and 8 for scanning. Light source 4, 30 image information
Slit 5, scanning first, second, and third mirrors 6,
7, 8 and the like are scanned and read in the sub-scanning direction.
Reader).

On the other hand, when an image is read using a flow scan, a document 20 is sequentially conveyed from an automatic document feeder (not shown), and the document is conveyed by a document conveying roller 12 to a position above the document flow reading glass table 11. Is passed through the original 20. At this time, the original 20 is illuminated by an illumination light source having an opening (aperture) 4a, and a reflected light beam based on image information from the illuminated original 20 passes through the slit 5, and the first, second, and third light beams are reflected. An image is formed on the surface of a line sensor 10 such as a CCD by an imaging lens 9 via mirrors 6, 7, and 8. Since the original 20 is sequentially conveyed and passed over the original flow reading glass table 11, the image information of the original 20 is read by obtaining a signal based on the image information of the original 20 in the sub-scanning direction. (Second reading device).

In the second reading apparatus, as shown in FIG. 2, the document 20 has a curvature substantially following the shape of the document transport roller 12 until the document 20 is fed by the document transport roller 12 and then leaves. Become. At that time, the original transport roller 12
When the axis M perpendicular to the original flow reading glass table 11 and the optical axis N of the imaging lens 9 coincide with each other through the center O of the
Can be read. At this time, the optical axis N and the normal line of the document 20 having the curvature (the normal line at the intersection P between the optical axis N and the document conveying roller 12) are parallel to each other, and the angle θ is 0 degree. In this state, the specular component of the illumination light illuminating the document 20 is not reflected in the direction of the optical axis N, so that the read image information is not affected by the surface condition (glossy) of the document 20. Absent.

However, usually, the scanning system in the automatic document feeder and the image reading device has a stationary position error when the scanning system is moved in the sub-scanning direction and then returned to the original position due to a mounting error or the like. As shown in (1), a relative shift amount Δ occurs in the sub-scanning direction (Y direction). That is, in FIG. 2, the axis M perpendicular to the document flow reading glass table 11 through the center O of the document feed roller 12 does not coincide with the optical axis N of the imaging lens 9 and is relatively Deviation Δ
Had occurred. Position (reading position) where the deviation amount Δ occurred
If the reading of the document 20 is performed in A _0, the curvature (warpage)
Of the original 20 (the optical axis N and the original transport roller 12)
Normal) L at an intersection A ₀ and will be occur a deviation of the optical axis N and the angle theta.

At that time, as described in the conventional problem, FIG.
As you can see, its position A ₀Original image information
Is read, if the angle between the illumination light and the optical axis N is 2θ
Illuminating light, that is, the incident angle θ with respect to the normal L
When there is illumination light, the reading position A of the original 20₀Specularly reflected in
And travels on the optical axis N, and its component is the CCD 10,
It becomes easy to be included in the image information of the manuscript 20. That
For example, if a glossy document is transported and read
If the image information of the original 20 is
Output, especially in high density areas such as black areas
High density (black background) is hard to come out
Inconvenience occurs.

Therefore, in this embodiment, when the image information of the original 20 is read by the reading unit 21 while the original 20 is being conveyed by the original conveying unit 12, the original conveying unit 12 and the reading unit 21 are relatively moved in the conveying direction. when having a certain read range out of a predetermined position (the sub-scanning direction), at the outermost end a ₀ of the conveying direction of the reading range, the outermost end of the minimum angle γ of the illumination light that illuminates the original 20 a ₀ The angle θ is larger than twice the angle θ formed between the normal line L of the original 20 at the position where the original is conveyed by the original conveying means 12 and the optical axis N of the reading means 21.

More specifically, in the present embodiment, the optical axis N of the imaging lens 9 and the light flux (illumination light) from the illumination light source 4 are used to prevent the specular reflection component from the original 20 from traveling to the optical axis N. When the minimum angle is γ (degrees), the angle is set so that 23 ° <γ <30 ° (1).

[0034] Also, when the optical axis N of the imaging lens 9, the angle between the normal line L at the intersection A ₀ of the optical axis N and the document conveying roller 12 and the theta (degrees), theta ≦ 11.5 ° ‥‥‥ (2).

Hereinafter, description will be made with reference to specific numerical examples.

The relative positional deviation between the axis M and the optical axis N perpendicular to the original flow reading glass table 11 through the center O of the original transport roller 12 is represented by Δ, and the radius of the original transport roller 12 is represented by R. Then, sin θ = Δ / R ‥‥‥ (3), and the relationship between the angle θ and γ at that time is γ> 2θ ‥‥‥ (4).

For example, in FIG.
Assuming that 2 is 20φ (radius R = 10 mm) and the relative displacement amount Δ = 2 mm, the angle θ in the figure is θ = 11.5
When the illumination light of the illumination system becomes 2θ = 23.0 degrees, the component that is specularly reflected by the original 20 is likely to be included in the CCD 10, that is, the image information of the original 20.

Therefore, in this embodiment, the specular reflection component from the original 20 is mixed into the image information by appropriately setting the angles γ and θ so as to satisfy the conditional expressions (1) and (2) as described above. , And the read image information can be read with high accuracy without being affected by the surface condition (glossy) of the document.

As described above, in the present embodiment, by appropriately setting the angles γ and θ so as to satisfy the conditional expressions (1) and (2), the scanning in the automatic document feeder and the image reading device is performed. Even if there is a relative misalignment in the sub-scanning direction due to a system mounting error or a stationary position error, the specular reflection component from the document is prevented from being mixed into the image information, and the read image information is It is not affected by the condition (glossy). As a result, a small-sized image reading device capable of reading images with high accuracy is obtained.

When reading the image information of the original by the first or second reading device, the light source 4, the slit 5, the first, second and third mirrors 6, 7, 8 for scanning, the image forming Lens 9,
Then, the line sensor 10 and the like may be integrally moved in the sub-scanning direction.

[Second Embodiment] Next, a second embodiment of the present invention will be described.

This embodiment differs from the first embodiment in that an adjusting means for adjusting the relative position in the sub-scanning direction between the automatic document feeder and the scanning system (image reading section) in the image reading apparatus is provided. That is. Other configurations and optical functions are substantially the same as those of the first embodiment, and thus, similar effects are obtained.

That is, in the present embodiment, the scanning system in the image reading apparatus is first configured for the optimal arrangement of the main body and the like and the need for miniaturization. That is, when the minimum angle γ is determined first,
By adjusting the relative position of the automatic document feeder and the scanning system in the sub-scanning direction by the adjusting means so as to satisfy the conditional expression (1) also in the system, the specular reflection component from the document is converted into image information. It prevents mixing.

Here, as an adjustment method, for example, there is a method of adjusting a position when the scanning system is moved to a lower portion of the original-flowing reading glass table and stands still. There is also a method of adjusting the position when the automatic document feeder is placed on the image reading apparatus, that is, adjusting the position of the mounting (arrangement) member.

As the detecting means for detecting the adjustment position, for example, a glossy black original chart is conveyed and read at the time of adjustment, and the position where the CCD output is minimized, that is, the regular reflection component is included in the CCD. The position which is not present is detected, and the position is adjusted based on the detection result.

As described above, in this embodiment, as described above, the relative position in the sub-scanning direction between the automatic document feeder and the scanning system in the image reading device is adjusted by the adjusting means so as to satisfy the conditional expression (1). This prevents the specular reflection component from the document from being mixed into the image information, and prevents the read image information from being affected by the surface condition (gloss) of the document. As a result, a small-sized image reading device capable of reading images with high accuracy is obtained.

In each of the embodiments, an example of the automatic document feeder using the document feed roller directly above the document reading position has been described. However, the present invention is not limited to this.
It is apparent that the present invention can be applied not only to a driving member such as a document conveying roller but also to an automatic document feeder having a fixed document holding member. This is because there is also a space limitation in the automatic document feeder with the fixed document holding member, and when the document is transported from the automatic document feeder to the document reading position on the document flow glass platen, the document delivery unit This is because the original is warped due to the height difference between the originals and the original is conveyed in a state where the original is warped (curvature).

In each embodiment, the minimum angle γ formed by the light beam (direct light) directly illuminating the original 20 from the illumination light source 4 and the optical axis N is set so as to satisfy the conditional expression (1). The present invention is not limited to this, and it is apparent that the present invention can be applied to a light beam (indirect light) via a reflecting member (for example, reference numeral 15 in FIGS. 1 and 2) on the opposite side of the illumination light source 4 with respect to the optical axis N. is there.

In each embodiment, the image reading apparatus having the first and second reading apparatuses has been described. However, the image reading apparatus may include only the second reading apparatus (flow scan).

[0050]

According to the present invention, as described above, conditional expression (1)
By appropriately setting the minimum angle γ so as to satisfy the condition (1), it is possible to prevent the specular reflection component from the original from being mixed into the image information. ), An image reading apparatus capable of reading an image with high accuracy can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an enlarged view of a reading unit during document conveyance shown in FIG. 1;

FIG. 3 is a schematic view of a main part of a conventional image reading apparatus.

FIG. 4 is a top view of a main part of the original mounting glass table when the original mounting glass table is viewed from above.

FIG. 5 is an enlarged view of a reading unit when the document is transported in FIG. 3;

FIG. 6 is an enlarged view of the reading unit during document conveyance in FIG. 5 further enlarged;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 original placing table 2 front original abutting nameplate 3 shading plate 4 illumination means 5 slit 6, 7, 8 scanning mirror 9 imaging means 10 reading means 11 original flow reading table 12 original transport means (original transport roller) 15 reflection Board 21 Scanning system 20, 30 Original

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/107 F term (Reference) 5B047 AA01 BA01 BA02 BB02 BC15 BC16 5C051 AA01 DA03 DB01 DB28 DC05 DC07 DE23 5C072 AA01 BA04 CA02 CA09 DA21 DA23 EA05 XA01

Claims (6)

[Claims] 1. An image reading apparatus for reading image information of a document by a reading means while conveying the document by the document conveying means, wherein the document conveying means and the reading means are relatively displaced from a predetermined position in a conveying direction. When a document has a certain reading range, the minimum angle of the illuminating light for illuminating the document at the extreme end in the transport direction of the reading range is set to the normal line of the document curved at the extreme end position by the document transport unit. An image reading apparatus, wherein the angle is greater than twice the angle formed by the optical axis of the reading means. 2. A first reading device for fixing an original and reading image information of the original using a scanning system, and a second reading device for reading the image information of the original while conveying and sequentially sending the original. Wherein the second reading device reads the image information of the document while the document is transported by the document transporting device, and the document transporting device and the reading device move relatively in the transport direction. When there is a certain reading range deviating from the predetermined position, the minimum angle of the illuminating light for illuminating the original is set at the extreme end of the reading range in the conveying direction by a curvature by the original conveying means at the extreme end position. An image reading apparatus which is larger than twice the angle formed between the normal line of the original and the optical axis of the reading means. 3. A transporting means for transporting a document onto a document flow reading table using a document transporting roller, an illuminating means for illuminating the document from the side opposite to the document transporting roller, and a light beam from the illuminating means. An image forming means for forming image information of the illuminated document on the reading means surface, wherein an angle formed by an optical axis N of the image forming means and a light flux from the illuminating means. An image reading apparatus, wherein 23 ° <γ <30 ° when the minimum angle is γ (degrees). Wherein when said optical axis N of the imaging means, the angle between the normal line L at the intersection A ₀ of the original conveying roller and the optical axis N theta (degrees), θ ≦ 11. The image reading device according to claim 3, wherein the angle is 5 °. 5. A first reading device that fixes an original and reads image information of the original using a scanning system, and a second reading device that reads the image information of the original while conveying and sequentially sending the original. Wherein the second reading device includes a conveying unit that conveys the original onto the original flow reading table using an original conveying roller, and illuminates the original from a side opposite to the original conveying roller. Illuminating means, and image forming means for imaging the image information of the document illuminated by the light beam from the illuminating means on the reading means surface, the optical axis N of the image forming means and the illuminating means An image reading apparatus characterized in that 23 ° <γ <30 °, where γ (degrees) is the minimum angle among the angles formed by the light flux from the lens. 6. upon said optical axis N of the imaging means, the angle between the normal line L at the intersection A ₀ of the original conveying roller and the optical axis N theta (degrees), θ ≦ 11. The image reading device according to claim 5, wherein the angle is 5 °.