JPH10210227A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the image reader with high quality which has no difference in image read between a running read system and a document fixed system by determining the read reference position of an image read means so that a range of errors in image position read by an image read means during a running scan is all included in a range of an image at a flat part. SOLUTION: A read position line D of a contact type image sensor is set at a position F shifting downstream by ΔL from a line which passes the axis of a document pressure roller 7a and is perpendicular to a document platen. Namely, the position of the line F as a read reference position is so set that a range wherein a line D as an image read position of the contact image sensor is possibly positioned during the running read is all included in the downstream side of the line C. Consequently, the angle θs4 of incidence at which light irradiating a document surface from a light source is made incident on a SELFOC lens becomes nearly equal to the angle θb2 of incidence when a book document is read, thereby generating on difference of a read image between a book document read and a sheet document read.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copying machine,
The present invention relates to an image reading apparatus such as a facsimile, a scanner, or the like that reads an original, and particularly relates to an image reading apparatus that has both a flow-reading type image reading and an original fixing type image reading (hereinafter, referred to as a collocated type).

[0002]

2. Description of the Related Art Conventionally, as this type of image reading apparatus,
In general, the image reading position of the moving-reading method and the image reading position of the document fixing method are arranged on the same platen and share one image reading sensor. Further, in such an image reading section of the parallel reading type image reading apparatus, the sheet S is conveyed from above the image reading position of the original fixed type to the image reading position of the flow reading type as shown in FIG. In many cases, the size of the device is reduced.

Hereinafter, the configuration will be described in detail.

Reference numeral 130a denotes a platen glass, and reference numeral 108 denotes a contact image sensor, which is a light emitting diode 108d for illuminating the surface of the document S on the surface of the platen glass 130a.
And a selfoc lens 108b that forms an image of reflected light from the surface to be read, and an image sensor 108c that is disposed immediately below the selfoc lens 108b and forms an image of the reflected light
It has.

A document pressing roller 107a is provided on the surface of the document table glass 130a at a position facing the selfoc lens 108b. A predetermined gap Δx is formed between the original pressing roller 107a and the original platen glass 130a.
And its vertical movement is regulated.

Reference numerals 106e and 106f denote a pair of rollers for feeding a document into the gap Δx (hereinafter, referred to as a feeding roller pair). This feed roller pair is provided above the document reading unit as shown in the figure in order to be constrained by the positional relationship with the fixed document reading unit or to smoothly convey with the help of gravity. ing.

The document S is transported further downstream by the feed roller, and the leading end of the document S
g, 106h, and the trailing edge of the original is
06e and 106f, the sheet is then discharged to a discharge tray 109 by a pair of discharge rollers.

With the above configuration, the reading of the document S is performed continuously from the leading edge of the document S entering the reading position 107 until the trailing edge of the document S reaches the reading position 107.
Conventionally, the reading position 107 is set immediately below the document pressing roller 107a because, for example, the document is less likely to undulate and easily focused. That is, the position of the contact type image sensor 108 at the time of reading a document is set at a position where the optical axis D of light incident on the image sensor 108c intersects the axis of the document pressing roller.

When reading an image in a fixed document mode, such as when reading a book document, the driving means moves the contact image sensor 108 in the direction A in the figure based on a signal from the control system. By this movement, the original placed on the platen glass surface is read.

[0010]

However, in such a conventional example, the contact-type image sensor 1 is used for reading an image by a flow-reading method and an image reading by a document fixing method.
08 is shared, it is not possible to accurately determine and fix the position of the contact type image sensor as in an image reading apparatus that can only read images in the flow reading system.

When an image is read by the flow reading method, a positioning sensor or the like is used for positioning the contact-type image sensor, and errors tend to occur.

That is, the image reading position may be shifted from the position immediately below the document pressing roller upstream (FIGS. 11A and 11B) or downstream (FIGS. 12 and 13) by a small distance Δl. is there.

In such a case, the first problem is the inclination of the document at the image reading position. If the surface to be read of the document is inclined in the flow-reading method as shown in FIG. 11, the amount of light incident on the image sensor 108c differs from that in the case of the document fixing method.

That is, if the light emitting diode 108d is located on the upstream side in the transport direction as shown in FIG.
When the light from the light emitting diode 108d is specularly reflected on the read surface of the original, the reflected light is
The angle made with the light incident on the document is smaller in the flowing reading method (θs1) than in the original fixing method (θb1), so that the flowing reading method has a larger amount of light and makes the read image brighter.

On the other hand, as shown in FIG.
If 08d is located on the downstream side in the transport direction, conversely, θs1> θb1, and the flow reading method has a smaller amount of light and makes the read image darker, which also causes a difference in the read image between the two. In particular, when a photographic original is read with multi-valued gradation (halftone), the difference in gradation is easily noticeable.

In order to solve such a problem, there is a method of improving the accuracy of the components of each part and the accuracy of detecting the stop position in order to improve the accuracy of the stop position of the contact type image sensor. Then productivity becomes very bad.

The next problem is the position of the light emitting diode 108d as the light source.

As shown in FIGS. 12 and 13, even if the surface to be read of a document is not inclined and horizontal in the flow reading method, the light emitting diode 108d as a light source is provided on the upstream side in the transport direction. Reads an area without a document black.

That is, when reading a document, the angle θs2
Is almost equal to θs3, so that there is no difference in the amount of light incident on the image sensor 108c in the above two methods, and no difference in the brightness of the read image occurs.

However, at the time of reading an image by the flow reading method,
In the area other than the document, the light emitting diode irradiates the document pressing roller 107a (FIG. 13). in this case,
When the light from the light emitting diode is specularly reflected by the document pressing roller, the angle θs3 between the reflected light and the incident light to the image sensor 108c is larger than θb2, and the amount of light incident on the sensor surface is reduced. When reading a document of a size smaller than the range, an area other than the document is read in black.

In order to solve such a problem, there are methods such as enlarging a roller diameter and pressing an original with a flat plate. However, this leads to an increase in the size of the apparatus or an increase in the jam of the original. Not so appropriate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention that there is no difference in image reading between the flow reading method and the original fixing method, or that the reading area does not differ. It is an object of the present invention to provide a high-quality image reading apparatus capable of reading an area other than the original as having no information amount even when reading a small original.

[0023]

According to the present invention, in order to achieve the above object, an image reading section of a flow-reading type and an image reading section of a fixed document type are provided side by side. Sharing, the image reading means moves substantially in parallel, thereby performing the image reading of the flow reading method on substantially the same plane as the image reading surface in the original fixed method, and the image reading section of the flow reading method is A sheet conveying path having a flat portion along a plane and a curved portion curved along the rotating body,
In an image reading apparatus that sets the position of an image reading unit in a drift reading method, so as to read an image of a sheet conveyed on the sheet conveyance path between the rotating body and the plane,
The reading reference position of the image reading means is determined so that the error range of the image position read by the image reading means at the time of moving reading is entirely included in the range of the image in the flat portion.

Further, a light source provided in the image reading means is arranged on a side opposite to the curved portion with respect to the image reading position.

[0025]

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, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

FIG. 1 is a schematic sectional view of a document reading unit when the present invention is applied to a facsimile.

In FIG. 1, reference numeral 30 denotes a flatbed scanner, which is an image reading device, which reads a document B placed on a platen glass 30a. Reference numeral 2 denotes a pressure plate, which can be opened and closed by a user up and down, and which presses a document B placed on a platen glass 30a. Reference numeral 8 denotes a contact type image sensor as image reading means for reading an image.

An upper surface of the pressure plate 2 has a document table 2b configured to be able to stack a plurality of documents S. Reference numeral 6 denotes a document transport unit that transports the document S while separating the document one by one, and reads the document while transporting the document to the sheet reading unit 7. Here, the document feeder 6 is provided in a part of the pressure plate 2 and moves up and down as the pressure plate 2 opens and closes. Reference numeral 9 denotes a document discharge tray on which discharged documents are stacked. (Flatbed Scanner Unit) The flatbed scanner unit 30 is provided with a platen glass 30a on which a document is placed in order to read a thick document such as a book in a stationary state.

Reference numeral 2e denotes an original pressing plate, which is supported so as to be vertically movable with respect to the pressing plate 2, and presses the original on the original platen glass 30a by closing the pressing plate 2. Reference numeral 30b denotes a frame serving as a structure of the flatbed scanner unit 30, which supports the original table glass 30a. Document holding plate 2e
A part of the platen glass 30a opposed thereto and the scanning part of the contact type image sensor 8 thereunder form an original-fixed type image reading unit.

Here, the pressure plate 2 has a rotation center (not shown) (not shown) provided between the frame 30b and the rotation center (not shown).
The pressure plate 2 is configured to be swingable by a predetermined angle with respect to the frame 30b, and the user opens the pressure plate 2 and places a document on the platen glass 30a.

The contact-type image sensor 8 is driven in the sub-scanning direction (A direction in the figure) of the book document by driving means (not shown). The contact type image sensor 8 includes a platen glass 30a.
The contact type image sensor 8 and the original platen glass 3 are urged toward the sub-scanning direction by the driving means described above.
By keeping the distance from Oa constant, the height of the focal position of the contact type image sensor 8 on the platen glass 30a becomes constant, and a good image without a focal position shift can be obtained.

When reading the original B on the original glass 30a, the original is read while the contact image sensor 8 is moved in the sub-scanning direction (A direction).

(Original Conveying Section) The original conveying section 6 separates the originals S stacked on the original placing table 2b one by one by a preliminary conveying roller 2d and a separating roller 6b pressed against a separating piece 6a by a preliminary conveying pressing plate 2c. Then, the sheet is further conveyed to the sheet reading unit 7 by the feeding roller 6f pressed by the pressing spring and the document feed roller 6e. 7a is a document pressing roller. In the present embodiment, a white roller of φ16 is used.

At the time of reading a sheet document by the flow reading method,
The contact type image sensor 8 is moved from the fixed image reading section of the original to a position substantially parallel to the lower side of the original pressing roller 7a, and the reading is performed in a stationary state. Here, the original pressing roller 7
a, the original S is transported onto the original platen glass 30a surface, which is substantially the same as the image reading surface in the original fixing method, while the original S
Is read. The read document is discharged to a document discharge tray 9 by a document discharge roller 6g and a document discharge roller 6h.

The document feeder 6 is provided on a part of the pressure plate 2 as described above. When the pressure plate 2 is opened, the document feeder 6 is also raised, so that the document feed path can be easily moved in case of a document jam or the like. Can be canceled.

A slider 2 slidable in a direction perpendicular to the direction in which the original S is transported (in the width direction of the original S) is mounted on the original placing table 2b.
is provided so that both sides of the document S placed on the document table 2b can be aligned by the slider 2a. (Explanation of Configuration of Document Conveying Unit Characteristic of the Present Invention) FIG.
FIG. 2A is a detailed view of a sheet document reading unit of the facsimile of FIG. 1 and shows a flow reading type image reading unit.

In FIG. 2A, the document conveying path includes a document upper guide 6j for guiding the upper surface of the document and document lower guides 6k and 6l for guiding the lower surface of the document. (Contact image sensor unit) 8 is a contact image sensor. The contact image sensor 8 includes a light emitting diode 8d as an illuminating member for illuminating the reading surface of the document as shown in FIG. It comprises a SELFOC lens 8b through which the reflected light passes, and an image sensor 8c as an image reading member disposed immediately below the lens to form an image of the reflected light. Here, the SELFOC lens 8b is of a long focus type, and is set so as to focus on the surface of the platen glass 30a having a thickness of 3 mm.

A document holding roller 7a, which is a rotating body, is provided on the surface of the document table glass 30a and at a position facing the SELFOC lens 8b. A predetermined gap Δx is formed between the document pressing roller 7a and the document table glass 30a.

The original S sent to the reading unit 7 is restricted from moving in the vertical direction by the original pressing roller 7a and the original platen glass 30a, and can move in the vertical direction within the gap Δx. The read surface exists in the gap Δx.

Here, the gap Δx has such a size that a predetermined reading resolution (MTF) can be secured by adjusting the focal position of the selfoc lens 8b to the vicinity of the center of the gap Δx. The reading is performed without.

In this embodiment, the gap Δx is set to 0.2 mm.

Reference numerals 6e and 6f denote a pair of rollers for feeding a document into the gap Δx (hereinafter, referred to as a feeding roller pair). This feed roller pair is provided above the original reading section as shown in the figure in order to be constrained by the positional relationship with the original fixed reading section or to smoothly convey with the help of gravity. ing. The paper discharge roller 6h is pressed by the paper discharge roller 6g to form a nip. Here, the nip portion of the discharge roller is substantially an extension of the surface of the platen glass 30a, and the document surface is placed on the platen glass while the document is supported by the gap Δx between the document pressing rollers 7a and the nip portion of the discharge roller. It is arranged so as to be substantially parallel to the surface 30a.

In the transport path for transporting the document to the pair of paper discharge rollers after passing through the image reading unit 7 through the pair of feed rollers,
It has a curved portion X in contact with the document pressing roller 7a and a flat portion Y in contact with the document table glass 30a. (FIG. 2B) On the other hand, the reading position line D of the contact image sensor is shifted to the downstream side by ΔL from the line C passing through the axis of the document pressing roller 7 a and perpendicular to the document table (sheet reading). Position). This ΔL indicates that the reading position line D is the line C even when the dimensions of the parts of the apparatus vary.
It is a numerical value determined based on tolerance calculation and part dimensional management data so as not to go further upstream.

That is, the range (error range) where the line D, which is the image reading position of the contact type image sensor, may be located at the time of moving reading is all included on the downstream side of the line C as the flat portion. , The position of the line F which is a reading reference position is set. In the present embodiment, the shift amount ΔL of the reading reference position line F of the contact type image sensor
Is set to 0.5 mm.

With the above configuration, when the original is read (FIG. 3), since the original platen glass 30a and the original surface are almost parallel, the light irradiated from the light source on the original surface enters the Selfoc lens. Since θs4 is substantially equal to the incident angle θb2 when reading the book document, the light amount on the sensor surface is substantially equal between the sheet and the book. Therefore, there is no difference in the read image between the book original reading and the sheet original reading.

When reading an original having a small size in the longitudinal direction (main scanning direction) of the original pressing roller 7a,
When reading outside the width of the document in the longitudinal direction of the document pressing roller 7a (shown in FIG. 5), the incident angle θs6 at which the light illuminated from the light source is reflected by the document pressing roller 7a and enters the selfoc lens. It becomes smaller than the incident angle θs5 in the document passing area (shown in FIG. 4). That is, since the light is close to regular reflection, the surface of the document pressing roller 7a is read as white, and the read image does not become black information.

In particular, when the reading position of the sensor is shifted due to the variation of the intersection of the parts or the intersection of the position detection sensors, and when the reading position is shifted to the upstream side by Δl1, which is the maximum error (shown in FIG. 6).
Is closer to the line C of the document holding roller 7a, but the line C
The distance .DELTA.L is sufficiently large so that the crossing reading position line does not go upstream of the document pressing roller 7a, and the incident angle .theta.s7 at the time of reading a sheet is almost the same as the incident angle .theta.b2 of reading a book. Therefore, there is no difference between the read images. Also, when reading the outside of the document passage (shown in FIG. 7) at the time of sheet reading, the incident angle θs8 is substantially equal to the incident angle θs7 in the sheet passing area, and the outside of the sheet passing area does not become a shadow.

Further, the reading position of the sheet document is shifted to the downstream side by Δ.
When the angle is shifted by l1 (shown in FIG. 8), the angle of the document surface does not change, and the angle between the sheet reading incident angle θs9 and the book reading incident angle θb2 is substantially equal. Does not occur as well. Incident angle θ outside original width (shown in FIG. 9) when reading small-size originals
Since s10 is smaller than the incident angle θs9 in the document passing area and the incident light increases, there is no shadow problem even when reading outside the sheet passing area.

Strictly speaking, Δl1 is θs10
<Θs9 is a range in which the incident light to the image sensor 8c increases, and the light emitted from the light emitting diode 8d is directed to the axis of the document pressing roller toward the image sensor 8c (FIG. 9B). If the deviation θl1 is larger than that of ()), the problem of shadows also occurs. That is, the position of the line F is set such that the line F ± Δ11 is on the flat portion side of the line C and is included on the curved portion side of the line G.

As described above, there is no problem even if the reading position of the sheet document slightly deviates from the document pressing roller.

(Other Embodiments) In the above-described embodiment, the conveyance path is formed downstream of the original pressing roller with the original surface parallel to the original platen glass. Is formed, the sheet document reading position is set to be shifted upstream by ΔL from the line C of the document holding roller, and the light source is set to the sheet document, contrary to the first embodiment. A similar effect can be obtained by providing it further upstream from the reading position.

[0052]

According to the present invention, even if the accuracy of the components for positioning the reading means at the reading position of the sheet or the position detection sensor is rough, and even if the diameter of the document pressing roller is small, the light source for the sheet and the book can be used. Since the angle at which the light illuminated from above enters the reading unit can be made substantially equal, there is no difference in the read image between the flow reading method and the original fixing method.

Further, even when the original pressing roller is directly read out of the original range, the reflected light from the illumination is increased so that the original is not read in black. Therefore, it is possible to solve the problem that the transmission time increases due to an increase in the amount of fax transmission information.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a document reading unit of a facsimile according to an embodiment of the present invention.

2A is a detailed cross-sectional view of a sheet document reading unit of the facsimile of FIG. 1, and FIG. 2B is an enlarged cross-sectional view of an image reading position.

FIG. 3 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 9 is an enlarged cross-sectional view for detailed description of an image reading unit according to the embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating an image reading unit according to a conventional image reading apparatus.

FIG. 11 is a detailed cross-sectional view for explaining a problem of the image reading section of the conventional image reading apparatus.

FIG. 12 is a detailed cross-sectional view for explaining a problem of the image reading section of the conventional image reading apparatus.

FIG. 13 is a detailed cross-sectional view for explaining a problem of the image reading unit of the conventional image reading apparatus.

[Explanation of symbols]

2 pressure plate 6 document feeder 6e document feed roller 6f document feed roller 6g document discharge roller 6h document discharge roller 6j document upper guide 6k document lower guide 6l document lower guide 6m document presser plate 7 sheet reader 7a document press roller Reference Signs List 8 Contact image sensor 8b Selfoc lens 8c Image sensor 8d Light emitting diode 9 Document ejection tray 30 Flatbed scanner 30a Platen glass B Book document S Sheet document C Vertical line D lowered from the axis of the document pressing roller to the platen glass D Contact image sensor reading position line F Sheet reading reference position

Claims (2)

[Claims] An image reading section of a flow-reading type and an image reading section of a document fixing type are arranged side by side, and both types share an image reading means, and the image reading means moves substantially in parallel to fix the document. The image reading unit of the flow reading method performs image reading of the flow reading method on substantially the same plane as the image reading surface of the method, and the image reading unit of the flow reading method includes a flat portion along the plane, and a curved portion curved along the rotating body. Image reading for setting a position of an image reading means in a flow-reading system so as to read an image of a sheet conveyed on the sheet conveying path between the rotating body and the plane. In the apparatus, a reading reference position of the image reading means is determined so that an error range of an image position read by the image reading means at the time of moving reading is entirely included in an image range in the flat portion. Image reading device. 2. The image reading apparatus according to claim 1, wherein the illumination member provided in the image reading means is arranged on a side opposite to the curved portion with respect to the image reading position.