JP2002051194A - Image reader and image former - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain accuracy in correction of shading for a long period by making a reference, white reading face provided around a reading roller which is less likely to become dirty at carriage of a manuscript. SOLUTION: In an image reader which has an image reading unit arranged on a manuscript carriage path 7 where a manuscript D is carried; and a reading roller 12 counterposed to the image reader across the manuscript carriage path 7; and the periphery of the reading roller 12 is provided with a reference, white reading curved surface 13 which has the center B of curvature on a straight line (a) orthogonal to the axis A of the reading roller 12, and also is made of a curved surface positioned inside the locus of the largest peripheral face of the reading roller 12. At carriage of a manuscript, the reference white reading face 13 is less likely to come into contact with the manuscript D, dirt by the contact with the manuscript D is less likely to occur, and the accuracy in correction of shading can be maintained for a long period, even if the cleaning of the reference white reading face 13 is not conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus which conveys a document with an image reading section fixed in position and reads an image of the document, and an image forming apparatus using the image reading apparatus.

[0002]

2. Description of the Related Art In a sheet-through type image reading apparatus in which an original is conveyed with an image reading section fixed in position,
A white plate or a white roller is disposed at a position facing the image reading unit, and shading correction data is created by reading the white color.

However, the surface of a white plate or a white roller is a portion that comes into contact with a document conveyed when reading a document, and is easily stained. If the white plate or the white roller becomes dirty due to contact with the document, the accuracy of the shading correction is reduced.

Therefore, in a sheet-through type image reading apparatus, white data of a margin portion (white portion where no image is formed) at the leading end of a document or a portion through which a document does not pass (ie, a portion to which dirt is hardly adhered). In some cases, shading correction data is created based on read data of several pixels at the end in the main scanning direction.

However, there is not always a margin at the leading end of a document. Further, if the variation in the read data between the several pixels at the end in the main scanning direction is large, sufficient accuracy cannot be obtained by shading correction performed based on the read data.

Therefore, as in the image reading apparatus described in Japanese Patent Application Laid-Open No. 5-319613, a groove is formed in a part of the outer peripheral portion of the reading roller along the axial direction of the reading roller. It is known that a reference white portion is provided on a bottom surface portion and shading correction data is created by reading the reference white portion. According to this image reading apparatus, the conveyed document does not contact the reference white portion, and the reference white portion is not stained by contact with the document.

[0007]

However, according to the image reading apparatus described in Japanese Patent Laid-Open No. 5-319613, dust such as paper dust and toner shavings easily accumulates in the groove. Accumulation of dust on the surface reduces the accuracy of shading correction. Moreover, it is difficult to clean the dust accumulated in the groove.

Further, the state of light reflection changes abruptly between the curved surface portion and the groove portion on the outer peripheral portion of the reading roller. Therefore, when the edge of the groove is located on the back side of the document when reading the document, There is a problem that the edges appear as black shadows and the reading quality of the document is reduced. This problem is more likely to occur as the thickness of the document decreases.

Accordingly, the present invention is directed to an image reading apparatus and an image reading apparatus which can maintain the accuracy of shading correction for a long period of time because the reference white reading surface provided on the outer peripheral portion of the reading roller is less likely to be stained during document conveyance. It is an object of the present invention to provide an image forming apparatus.

Further, according to the present invention, dust hardly adheres to the reference white reading surface provided on the outer peripheral portion of the reading roller, and even if dust adheres, it can be easily cleaned, and the accuracy of shading correction is maintained for a long period of time. It is an object of the present invention to provide an image reading apparatus capable of performing the above-described operations and an image forming apparatus using the image reading apparatus.

Further, the present invention can prevent the deterioration of the reading quality of a document due to the provision of a reference white reading surface on the outer peripheral portion of the reading roller, and an image reading apparatus using the image reading apparatus. It is an object to provide a forming device.

[0012]

According to the first aspect of the present invention,
In an image reading apparatus having an image reading unit disposed on a document conveyance path on which a document is conveyed, and a reading roller disposed opposite to the image reading unit with the document conveyance path interposed therebetween, an outer peripheral portion of the reading roller And a reference white reading surface portion having a center of curvature on a straight line perpendicular to the axis of the reading roller and formed of a curved surface located inside the locus of the maximum outer peripheral surface of the reading roller.

Here, the maximum outer peripheral surface locus of the reading roller means a perfect circular outer peripheral surface of the reading roller without the reference white reading surface portion.

Therefore, the original conveyed for reading is conveyed at a position where one side thereof is in contact with the locus of the outermost peripheral surface of the reading roller, so that the reference white reading surface portion hardly comes into contact with the original during the original conveyance. Dirt is less likely to occur due to contact with the original. For this reason, the reference white reading surface can be maintained in a white state for a long time without cleaning, and the accuracy of shading correction can be maintained for a long time without cleaning the reference white reading surface. .

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the reference white reading surface portion is formed by connecting a plurality of curved surfaces having different curvature radii, each having a center of curvature positioned on the same straight line. It is formed.

Therefore, the connecting portion between the maximum outer peripheral surface locus of the reading roller and the reference white reading surface portion is smoothly connected, and the state of reflection of the light hitting the outer peripheral portion of the reading roller rapidly changes at the connecting portion. It will not change. Therefore, even when the edge of the reference white reading surface is located on the back side of the document when reading the document, the edge of the reference white reading surface is prevented from appearing as a black shadow, and the reference white reading surface is provided. This prevents the reading quality of the original from lowering.

According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the reference white reading surface portion includes:
It is formed in a convex shape.

Accordingly, dust hardly adheres to the reference white reading surface portion, and even if dust adheres, it can be easily cleaned.

According to a fourth aspect of the present invention, in the image reading apparatus according to the first or second aspect, the reference white reading surface portion includes:
It is formed in a concave shape.

Therefore, it becomes more difficult for the reference white reading surface portion to come into contact with the original when the original is transported.

According to a fifth aspect of the present invention, in the image reading apparatus according to the first aspect, the reference white reading surface portion is formed in a flat surface having a center of curvature located at infinity.

Therefore, the shape of the reference white reading surface is simplified, the formation of the reference white reading surface is facilitated, and the production of the reading roller having the reference white reading surface is facilitated.

The invention according to claim 6 is the invention according to claims 1 to 5
In the image reading device according to any one of the above, a connection portion between the maximum outer peripheral surface locus and the reference white reading surface portion is chamfered.

Therefore, the connecting portion between the maximum outer peripheral surface locus of the reading roller and the reference white reading surface portion is smoothly connected, and the state of reflection of the light hitting the outer peripheral portion of the reading roller sharply changes at the connecting portion. It will not change. Therefore, even when the edge of the reference white reading surface is located on the back side of the document when reading the document, the edge of the reference white reading surface is prevented from appearing as a black shadow, and the reference white reading surface is provided. This prevents the reading quality of the original from lowering.

According to a seventh aspect of the present invention, in the image reading apparatus according to the sixth aspect, the chamfering is performed by a curved surface having a curvature center at an arbitrary position.

Accordingly, the change in the light reflection state at the connection between the maximum outer peripheral surface trajectory of the reading roller and the reference white reading surface portion becomes more gradual, and the edge of the reference white reading surface portion becomes a black shadow during document reading. It is more reliably prevented from appearing.

[0027] The invention according to claim 8 provides the invention according to claims 1 to 7.
In the image reading device according to any one of the above, a plurality of the reference white reading surface portions are formed at predetermined intervals on an outer peripheral portion of the reading roller.

Therefore, when one reference white reading surface portion for reading the reference white for forming the shading correction data is stained, the reading of the reference white for forming the shading correction data is not stained. It is possible to change to the reference white reading surface, and even if one reference white reading surface is dirty, it is not necessary to immediately clean the reference white reading surface. It is possible to maintain the accuracy of shading correction for a long period of time and to clean the reference white reading surface. Can be extended. Further, it is possible to reduce the time required for the reference white reading surface portion to face the image reading portion, and to increase the image reading processing speed.

According to a ninth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to eighth aspects, wherein the image forming apparatus forms an image in accordance with image data read by the image reading apparatus. And a part.

Therefore, according to this image forming apparatus,
Since the accuracy of the shading correction in the image reading device is high and the reading quality of the document is high, high-quality image formation can be performed. Moreover, high-quality image formation can be maintained for a long period of time without cleaning the reading roller.

[0031]

FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. FIG. 1 is a longitudinal sectional front view showing a schematic structure of a copying machine as an image forming apparatus, and FIG. 2 is a longitudinal sectional front view of a reading roller used in an image reading device of the copying machine.

As shown in FIG. 1, the copying machine includes a scanner unit 1 as an image reading device and an image forming unit 2 for forming an image in accordance with image data read by the scanner unit 1.

The scanner section 1 includes a first image reading section 3, a second image reading section 4, which is an image reading section, a document setting section 5, a document discharge section 6, a document transport path 7, a large number of transport rollers 8, 1
Contact glass 9, second contact glass 10, first
Reading roller 11, second reading roller 12 that is a reading roller
And the like.

In the original setting section 5, an original D to be read is set.
(See FIG. 2) is set, and the document D from which the image has been read is discharged to the document discharge unit 6. Document transport path 7
Is a path provided between the document setting section 5 and the document discharge section 6, and a document from which an image is read is conveyed one by one. By switching the copy mode when reading a document, if the document D is a single-sided document, the image is read only by the first image reading unit 3,
When the document D is a double-sided document, the first image reading unit 3 and the second image reading unit 4 read an image.

The first image reading section 3 can read the image of the original D placed on the first contact glass 9 in a fixed position, or can read the image of the original D from the second contact glass 10 and the first reading roller 11. It is possible to read an image (front surface image) of the document D conveyed between them (that is, on the document conveyance path 7). When reading a document D conveyed on the document conveyance path 7, the first reading roller 11 is driven to rotate at the same speed as the conveyance roller 8 by a stepping motor (not shown) to move the document D conveyed to the first position. It acts to press against the two-contact glass 10.

The second image reading section 4 can read an image (back side image) of the document D conveyed on the document conveyance path 7. The second reading roller 12 is disposed to face the second image reading unit 4 with the document conveying path 7 interposed therebetween. When reading the document D by the second image reading unit 4, the second reading roller 12 uses a stepping motor (see FIG. (Not shown), and is rotated at the same speed as the conveyance roller 8, and acts so as to keep the distance between the image surface of the document D and the second image reading unit 4 constant. A reference white reading surface portion 13 (see FIG. 2) is formed on a part of the outer peripheral portion of the second reading roller 12, as will be described later in detail.

The image forming section 2 includes a photoreceptor 14, a laser unit 15, a developing unit 16, a transfer unit 17, a fixing unit 18, and the like. The surface of the photoconductor 14 is uniformly charged by a charger (not shown), and the image read by the first image reading unit 3 or the second image reading unit 4 on the surface of the photoconductor 14 is scanned by the laser unit 15. Written and an electrostatic latent image is formed. This electrostatic latent image is visualized as a toner image by supplying toner from the developing device 16,
The visualized toner image is transferred to the paper 20 fed from the paper feed cassette 19 by the operation of the transfer device 17. The sheet 20 onto which the toner image has been transferred is subjected to a fixing process in the fixing unit 18 and then discharged to a sheet discharge tray 21.

The second reading roller 12 is formed in a shape having a substantially circular cross section, and is formed in white using rubber, resin, or the like as a material. On a part of the outer peripheral portion of the second reading roller 12, a reference white reading surface portion 13 extending along the axial direction of the second reading roller 12 is formed. The reference white reading surface section 13 is where the second image reading section 4 reads white data as a reference for creating shading correction data.

The reference white reading surface portion 13 has a center of curvature B on a straight line a perpendicular to the axis A of the second reading roller 12 and has the maximum outer peripheral surface locus of the second reading roller 12 (the reference white surface portion 13 is not provided). The outer peripheral surface of the perfect circular shape of the second reading roller 12 in the state is formed by a convex curved surface located inside the portion (C shown by the solid line and the broken line) C.

In such a configuration, in this copying machine, when the double-sided copy mode is selected, the originals D set in the original set unit 5 are transported one by one through the original transport path 7 with the front side facing upward. The first image reading unit 3 reads an image on the front side, and the second image reading unit 4 reads an image on the back side. Then, the images read by the first and second image reading units 3 and 4 are copied on the front surface and the back surface of the same sheet 20, and two-sided copying is performed.

Here, in this copying machine, the first image reading unit 3 reads the white data as a reference for generating the shading correction data by using the first image reading unit 3 as a white reference plate (not shown). Is performed by sliding to a position opposite to. On the other hand, in the second image reading unit 4,
When it is detected that the reference white reading surface portion 13 faces the second image reading portion 4 based on an output from an encoder (not shown) for detecting the rotational position of the second reading roller 12, the second image reading portion The reading is performed by reading the reference white reading surface portion 13 at 4.

Here, at the time of document transport, the portion of the maximum outer peripheral surface trajectory C of the second reading roller 12 comes into contact with the facing surface (front surface) of the document D as shown in FIG. However, since the reference white reading surface portion 13 is located inside the maximum outer peripheral surface locus C of the second reading roller 12, the reference white reading surface portion 13 hardly comes into contact with the opposing surface of the document D, and stains due to contact with the opposing surface of the document D Hateful. For this reason, the reference white reading surface portion 13 can be maintained in a white state for a long time without cleaning, and the accuracy of shading correction can be maintained for a long time without cleaning the reference white reading surface portion 13. Can be.

Further, since the reference white reading surface section 13 is formed in a convex shape, dust such as paper dust and toner shavings hardly adhere to the reference white reading surface section 13, and even if it adheres, it is easily cleaned. can do.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments).

In this embodiment, the structures of the scanner unit 1 and the image forming unit 2 are the same as those of the first embodiment, and only the shape of the reference white reading surface 13a in the second reading roller 12a is different. Only the second reading roller 12a will be described.

At a part of the outer peripheral portion of the second reading roller 12a, there is formed a reference white reading surface portion 13a extending along the axial direction of the second reading roller 12a. While the reference white reading surface portion 13 of the first embodiment is formed by one curved surface, the reference white reading surface portion 13a of the present embodiment has a straight line orthogonal to the axis A of the second reading roller 12a. A plurality of (two in this embodiment) curved surfaces having different curvature radii with the center of curvature positioned on a are formed continuously. Specifically, the central portion of the reference white reading surface portion 13a is formed of a convex curved surface whose curvature center is B,
The center of curvature of both sides of the reference white reading surface portion 13a is B1.
And a convex curved surface.

In such a configuration, the reference white reading surface portion 13a also has the maximum outer peripheral surface locus C of the second reading roller 12a in the present embodiment, as in the first embodiment.
, The reference white reading surface portion 13a hardly comes into contact with the opposing surface of the original D when the original is conveyed, and dirt hardly occurs due to the contact with the opposing surface of the original D.
Therefore, the reference white reading surface portion 13a can be used without cleaning.
Can be maintained in a white state for a long period of time, and the accuracy of shading correction can be maintained for a long period of time without cleaning the reference white reading surface portion 13a.

Further, since the reference white reading surface portion 13a is formed in a convex shape, dust such as paper dust and toner shavings is unlikely to adhere to the reference white reading surface portion 13a, and even if it adheres, it is easily cleaned. can do.

The reference white reading surface portion 13a is formed by continuously forming curved surfaces having different radii of curvature.
The connection portion between the maximum outer peripheral surface locus C of the reading roller 12a and the reference white reading surface portion 13a is smoothly connected, and the state of reflection of light hitting the outer peripheral portion of the second reading roller 12a sharply changes at the connection portion. Will not change. For this reason, when reading the original, the reference white reading surface 13
The edge of the reference white reading surface portion 13a is prevented from appearing as a black shadow even when the edge portion of the document D is located on the back side of the document D, and the reading quality of the document D is reduced because the reference white reading surface portion 13a is formed. Is prevented from decreasing.

In this embodiment, the reference white reading surface portion 13a in which two types of curved surfaces are formed continuously has been described as an example. However, the number of types of continuous curved surfaces is not limited to two. Three or more types of curved surfaces may be formed continuously.

Next, a third embodiment of the present invention will be described with reference to FIG.
It will be described based on. In this embodiment, the structures of the scanner unit 1 and the image forming unit 2 are the same as those of the first and second embodiments, and only the shape of the reference white reading surface 13b in the second reading roller 12b is different. Only the second reading roller 12b will be described.

At a part of the outer peripheral portion of the second reading roller 12b, there is formed a reference white reading surface portion 13b extending along the axial direction of the second reading roller 12b. The reference white reading surface portion 13b is formed as a flat surface having a center of curvature at infinity on a straight line a perpendicular to the axis A of the second reading roller 12b.

In this configuration, as in the first and second embodiments, the reference white reading surface portion 13b is located inside the maximum outer peripheral surface locus C of the second reading roller 12b in this embodiment as well. For this purpose, the reference white reading surface 1
3b hardly comes into contact with the opposing surface of the original D when the original is conveyed, and dirt hardly occurs due to the contact with the opposing surface of the original D. For this reason, the reference white reading surface portion 13b can be maintained in a white state for a long time without cleaning, and the accuracy of the shading correction can be maintained for a long time without cleaning the reference white reading surface portion 13b. Can be.

Further, since the reference white reading surface portion 13b is formed in a flat surface, the reference white reading surface portion 13b
Dust, such as paper dust and toner shavings, does not easily adhere to the surface, and even if it does, it can be easily cleaned.

Further, since the reference white reading surface portion 13b is flat, the formation of the reference white reading surface portion 13b is facilitated, and the manufacture of the second reading roller 12b having the reference white reading surface portion 13b is facilitated. Become.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
It will be described based on. In this embodiment, the structures of the scanner unit 1 and the image forming unit 2 are the same as those of the first embodiment.
Reference white reading surface portion 13c of second reading roller 12c
Of the second reading roller 12c
Will be described only.

At a part of the outer peripheral portion of the second reading roller 12c, a reference white reading surface portion 13c extending along the axial direction of the second reading roller 12c is formed. While the reference white reading surface portions 13 and 13a of the first and second embodiments are formed in a convex shape, the reference white reading surface portion 13c of the present embodiment is different from the axis A of the second reading roller 12c. It is formed in a concave shape by a curved surface on a straight line a orthogonal to the outside and outside the second reading roller 12c and having a center of curvature B2.

In this configuration, in this embodiment, the reference white reading surface portion 13c is positioned inside the maximum outer peripheral surface locus C of the second reading roller 12c as in the first to third embodiments. Therefore, the reference white reading surface portion 13c hardly comes into contact with the facing surface of the document D when the document is conveyed, so that contamination due to contact with the facing surface of the document D hardly occurs. In addition, since the reference white reading surface portion 13c is concave, it is more difficult to contact the opposing surface of the original D when the original is conveyed, and it is more difficult for stains due to contact with the opposing surface of the original D to occur.

For this reason, the reference white reading surface portion 13c can be maintained in a white state for a long time without cleaning, and the accuracy of shading correction can be maintained for a long time without cleaning the reference white reading surface portion 13c. Can be maintained.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
It will be described based on. In this embodiment, the structures of the scanner unit 1 and the image forming unit 2 are the same as those of the first to fourth embodiments, and the only difference is the shape of the reference white reading surface unit 13d in the second reading roller 12d. Only the second reading roller 12d will be described.

A reference white reading surface portion 13d extending along the axial direction of the second reading roller 12d is formed in a part of the outer peripheral portion of the second reading roller 12d. The reference white reading surface portion 13d includes a curved surface on a straight line a orthogonal to the axis a of the second reading roller 12d and having the center of curvature B2 outside the second reading roller 12d, and the curved surface and the second reading surface. The connection portion of the roller 12d with the maximum outer circumferential surface locus C is formed by a chamfered surface. This chamfer,
This is performed by a curved surface having the centers of curvature B3 and B4 at arbitrary positions.

In this configuration, as in the first to fourth embodiments, in this embodiment, the reference white reading surface portion 13d is positioned inside the maximum outer peripheral surface locus C of the second reading roller 12d. Therefore, the reference white reading surface portion 13d hardly comes into contact with the facing surface of the document D when the document is transported, so that contamination due to contact with the facing surface of the document D hardly occurs. In addition, since the reference white reading surface portion 13d is concave, it is more difficult to come into contact with the opposing surface of the original D during the conveyance of the original, and the dirt due to the contact with the opposing surface of the original D is harder to occur.

Therefore, the reference white reading surface portion 13d can be maintained in a white state for a long period of time without cleaning, and the accuracy of shading correction can be maintained for a long period of time without cleaning the reference white reading surface portion 13d. can do.

In the reference white reading surface portion 13d, since the connecting portion with the maximum outer peripheral surface locus C of the second reading roller 12d is chamfered with a curved surface, the maximum outer peripheral surface locus C of the second reading roller 12d and the reference outer peripheral surface locus C are also used. The connection portion with the white reading surface portion 13d is smoothly connected, and the second reading roller 1
The reflection state of the light hitting the outer peripheral portion of 2d does not suddenly change at the connection portion. Therefore, even when the edge of the reference white reading surface portion 13d is located on the back side of the document D when reading the document, the edge of the reference white reading surface portion 13d is prevented from appearing as a black shadow. The reading quality of the document D is prevented from being reduced due to the formation of the surface portion 13d.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
It will be described based on. In the present embodiment, the structures of the scanner unit 1 and the image forming unit 2 are the same as those of the first to fifth embodiments, and only the shape of the reference white reading surface unit 13e in the second reading roller 12e is different. Only the second reading roller 12e will be described.

On a part of the outer peripheral portion of the second reading roller 12e, a plurality of reference white reading surface portions 13e extending along the axial direction of the second reading roller 12e at equal intervals (in this embodiment, a plurality of reference white reading surface portions 13e). 4) are formed. Each of the reference white reading surface portions 13e is the reference white reading surface portion 13 described with reference to FIG.
And has a center of curvature B on a straight line a perpendicular to the axis A of the second reading roller 12e, and is formed of a convex curved surface located inside the maximum outer peripheral surface locus C of the second reading roller 12e. Have been.

In this configuration, the reference white reading surface portion 13e also has the maximum outer peripheral surface locus C of the second reading roller 12e in the present embodiment, as in the first embodiment.
, The reference white reading surface portion 13e hardly comes into contact with the opposing surface of the original D when the original is conveyed, and dirt due to the contact with the opposing surface of the original D hardly occurs.
For this reason, even if the cleaning is not performed, the reference white reading surface portion 13e
Can be maintained in a white state for a long period of time, and the accuracy of shading correction can be maintained for a long period of time without cleaning the reference white reading surface portion 13e.

Furthermore, since the reference white reading surface portion 13e is formed in a convex shape, dust such as paper dust and toner shavings is unlikely to adhere to the reference white reading surface portion 13e, and even if it adheres, it is easily cleaned. can do.

Since four reference white reading surface portions 13e are formed on the outer peripheral portion of the second reading roller 12e,
When one reference white reading surface portion 13e that has been reading the white data for shading correction data creation becomes dirty, the reference white reading surface portion 13e that reads the white data is changed to another reference white reading surface portion 13e. can do. That is, even if one reference white reading surface portion 13e becomes dirty, it is not necessary to immediately clean the reference white reading surface portion 13e, and the interval for cleaning the reference white reading surface portion 13e can be further extended.

Further, since a plurality of reference white reading surface portions 13e are provided, it is necessary for the reference white reading surface portion 13e to face the second image reading portion 4 in order to read white data serving as a reference for creating shading correction data. The time can be reduced, and the processing speed for image reading can be increased.

In the present embodiment, the second reading roller 12e having four reference white reading surface portions 13e is described. However, the number of the reference white reading surface portions 13e is four.
The number is not limited to two and may be two or three.

In this embodiment, each of the reference white reading surface portions 13e is replaced with the reference white reading surface portion 1 described with reference to FIG.
3 has been described as an example.
Or the reference white reading surface portions 13a, 13 described in FIG.
A plurality of members having the same shape as b, 13c, and 13d may be formed.

[0073]

According to the image reading apparatus of the present invention, a reference white reading surface portion is provided on the outer peripheral portion of the reading roller arranged opposite to the image reading portion, and the reference white reading surface portion is connected to the axis of the reading roller. It has a center of curvature on a straight line perpendicular to the center and is formed of a curved surface located inside the locus of the maximum outer peripheral surface of the reading roller.Therefore, the reference white reading surface portion hardly comes into contact with the original when the original is transported. Dirt is less likely to occur, the reference white reading surface can be maintained in a white state for a long time without cleaning, and the accuracy of shading correction can be maintained for a long time without cleaning the reference white reading surface. Can be.

According to the second aspect of the present invention, in the image reading apparatus according to the first aspect, the reference white reading surface portion is formed by connecting a plurality of curved surfaces having different curvature radii, each having a center of curvature on the same straight line. As a result, the connecting portion between the maximum outer peripheral surface locus of the reading roller and the reference white reading surface portion is smoothly connected, and the reflection state of light hitting the outer peripheral portion of the reading roller sharply changes at the connecting portion. To prevent the reference white reading surface from appearing as a black shadow even when the edge of the reference white reading surface is positioned on the back side of the document when reading the document.
It is possible to prevent the reading quality of the original from being deteriorated due to the provision of the reference white reading surface portion.

According to the third aspect of the present invention, in the image reading device according to the first or second aspect, since the reference white reading surface is formed in a convex shape, dust hardly adheres to the reference white reading surface. Even if dust adheres, it can be easily cleaned.

According to the fourth aspect of the present invention, in the image reading apparatus according to the first or second aspect, the reference white reading surface portion is formed in a concave shape, so that the reference white reading surface portion is further enhanced when the original is transported. And it is possible to further prevent the occurrence of dirt due to contact with the document.

According to the fifth aspect of the present invention, in the image reading apparatus according to the first aspect, the reference white reading surface portion is formed as a flat surface having a center of curvature located at infinity. The shape of the surface portion is simplified, the formation of the reference white reading surface portion can be facilitated, and the production of the reading roller having the reference white reading surface portion can be facilitated.

According to the sixth aspect of the present invention, in the image reading apparatus according to any one of the first to fifth aspects, the connecting portion between the maximum outer peripheral surface locus and the reference white reading surface portion is chamfered. The connecting portion between the maximum outer peripheral surface locus of the roller and the reference white reading surface portion is smoothly connected, so that the reflection state of light hitting the outer peripheral portion of the reading roller does not suddenly change at the connecting portion. However, even when the edge of the reference white reading surface is located on the back side of the document when reading the original, it is possible to prevent the edge of the reference white reading surface from appearing as a black shadow, and the provision of the reference white reading surface has This can prevent the deterioration of the original reading quality.

According to the seventh aspect of the present invention, in the image reading apparatus according to the sixth aspect, the chamfering is performed on a curved surface having a center of curvature at an arbitrary position. The change in the light reflection state at the connection portion with the reference white reading surface can be made more gradual, and it is further ensured that the edge of the reference white reading surface appears as a black shadow when reading the original. Can be prevented.

According to the invention described in claim 8, in the image reading apparatus according to any one of claims 1 to 7, a plurality of reference white reading surface portions are formed on the outer peripheral portion of the reading roller at predetermined intervals. In the case where one reference white reading surface that has been reading white data for shading correction data creation becomes dirty, the reading of white data can be changed to another reference white reading surface that is not stained, Even if one reference white reading surface is soiled, it is not necessary to immediately clean the reference white reading surface, so that the accuracy of shading correction can be maintained for a long period of time and the interval for cleaning the reference white reading surface can be extended. Further, since there are a plurality of reference white reading surface portions, it is possible to reduce the time required for the reference white reading surface portion to face the image reading portion for reading white data, and to increase the image reading processing speed. it can.

According to the ninth aspect of the present invention, an image reading apparatus according to any one of the first to eighth aspects, and an image forming apparatus that forms an image in accordance with image data read by the image reading apparatus. Since the image reading unit includes the image forming unit, the accuracy of shading correction in the image reading device is high and the reading quality of the document is high, so that high-quality image formation can be performed. Moreover, high-quality image formation can be maintained for a long period of time without cleaning the reading roller.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing a schematic structure of a copying machine which is an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional front view of a reading roller used in the image reading apparatus of the copying machine.

FIG. 3 is a vertical sectional front view of a reading roller according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional front view of a reading roller according to a third embodiment of the present invention.

FIG. 5 is a vertical sectional front view of a reading roller according to a fourth embodiment of the present invention.

FIG. 6 is a vertical sectional front view of a reading roller according to a fifth embodiment of the present invention.

FIG. 7 is a vertical sectional front view of a reading roller according to a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Image forming part 4 Image reading part 7 Original conveyance path 12, 12a, 12b, 12c, 12d, 12e Reading roller 13, 13a, 13b, 13c, 13d, 13e Reference white reading surface part C Maximum outer periphery of reading roller Surface locus D manuscript

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Kubo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Motoya Sano 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Wataru Nara 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Yoshikazu Inoue 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company ( 72) Inventor Hiroyuki Kawamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yasuyuki Nomizu 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (Reference) 2H076 AA58 BA24 BA96 5B047 AA01 BA01 BC18 CB30 5C062 AB17 AB32 AD00 BA06 5C072 AA01 BA07 BA13 NA01 RA16 XA01

Claims (9)

[Claims] 1. An image reading apparatus comprising: an image reading unit disposed on a document conveyance path on which a document is conveyed; and a reading roller disposed opposite to the image reading unit with the document conveyance path interposed therebetween. A reference white reading surface portion having a center of curvature on a straight line perpendicular to the axis of the reading roller and having a curved surface positioned inside a locus of a maximum outer peripheral surface of the reading roller is provided on an outer peripheral portion of the reading roller. An image reading apparatus characterized by the above-mentioned. 2. The image according to claim 1, wherein the reference white reading surface portion is formed by continuously forming a plurality of curved surfaces having different curvature radii, each having a center of curvature positioned on the same straight line. Reader. 3. The image reading apparatus according to claim 1, wherein the reference white reading surface portion is formed in a convex shape. 4. The image reading apparatus according to claim 1, wherein the reference white reading surface portion is formed in a concave shape. 5. The image reading apparatus according to claim 1, wherein the reference white reading surface portion is formed as a flat surface having a center of curvature located at infinity. 6. The image reading apparatus according to claim 1, wherein a connection portion between the maximum outer peripheral surface locus and the reference white reading surface portion is chamfered. 7. The image reading apparatus according to claim 6, wherein the chamfering is performed on a curved surface having a curvature center at an arbitrary position. 8. The image reading apparatus according to claim 1, wherein a plurality of said reference white reading surface portions are formed at predetermined intervals on an outer peripheral portion of said reading roller. 9. An image reading apparatus according to claim 1, further comprising: an image forming unit configured to form an image in accordance with image data read by the image reading apparatus. Image forming device.