JP2002290671A - Image scanner, imaging device, facsimile machine, and shading data forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image scanner which is capable of keeping data on shading density uniform by using shading data as they are if it is determined that contamination in a target region of prescribed width is low enough in degree not to cause hindrance when the target region of prescribed width is red in so as to acquired shading data on the white roller of an image scanner of a moving original exposure type. SOLUTION: The target region of prescribed width and also all the peripheral surface of a white roller are read in at the same time, an average value Dsg(n) of each pixel in the target region and an average value Drl(n) of each pixel on the whole peripheral surface are calculated (S4 and S6), the average values Dsg(n) and Drl(n) are compared with each other (S8), it is determined whether the degree of contamination in each pixel in the target region is allowable or not, and when the average value Dsg(n) of the target region is higher than the average value Drl(n) of the whole peripheral surface (Y of S8), it can be determined that the contamination of the concerned target region is higher than those of the other regions, so that the average value Dsg(n) of the pixel of the concerned target region can be used as proper shading data (S9).

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, an image forming apparatus, a facsimile apparatus, and a shading data creating method.

[0002]

2. Description of the Related Art In a conventional image reading apparatus of a movable image reading section typified by a flat bed type, the density of a reference white plate arranged while a carriage moves to an effective reading range while increasing the speed is read. Thus, shading data for white shading correction is generated. Further, in an image reading unit of a fixed image reading unit represented by a sheet through type, a density of a reference white plate or a white roller disposed on a surface opposite to a fixed reading position is read, so that white shading correction is performed. Shading data is being generated.

However, in the conventional shading data generation technology, dirt adheres to the surface of the reference white plate or the white roller with the passage of time, and the white density to be used as a reference varies depending on the reading position of the reference white plate or the white roller.
The density uniformity required to generate shading data cannot be maintained. In particular, in the case of the sheet-through type, since the document is conveyed on the surface of the reference white plate and the white roller, the reference white plate and the white roller become dirty as the frequency of use increases.

Therefore, in a sheet-through type image reading apparatus, white data of a margin at the leading end of a document and data of several pixels at an end of the main scanning direction through which a document does not pass (that is, where dirt is hard to adhere) are used. There are prior arts that generate shading data.

According to Japanese Patent Application Laid-Open No. Hei 5-319613, a groove (concave groove) extending in the axial direction is formed on a part of the peripheral surface of a reading roller disposed opposite to a reading position, and the concave groove is formed. A technology is disclosed in which the bottom surface of a reference white portion is used as a reference white portion for generating shading data so that the reference white portion is less likely to become dirty even when a document is conveyed.

[0006]

However, in the case of the prior art in which shading data is generated based on white data of a margin at the leading end of a document and data of several pixels at an end portion in the main scanning direction through which the document does not pass. However, in the former case, there is not always a margin at the leading edge of the document, and even in the latter case, if the sensitivity variation between pixels in the main scanning direction of a photoelectric conversion element such as a CCD is large, some pixels There is a problem that shading data generated based on white data cannot provide a sufficient shading correction effect.

In the technique disclosed in Japanese Patent Application Laid-Open No. 5-319613, paper dust and toner shavings and dust generated as the amount of document transport increases increase in the concave groove of the reading roller. However, the cleaning property is poor, and it is difficult to recover the original white state. In addition, because of the concave groove structure, a shadow of the concave groove formed on the peripheral surface of the reading roller due to irradiation of light from the light source of the reading unit is formed, and the image quality when a document is read is deteriorated. Trouble occurs. In particular, thin documents are easily affected by shadows.

However, in consideration of such a conventional technology, for example, in a system using a white roller using a perfect circular roller which is easy to clean, it is easy to get dirty, but it is not always possible to get dirty all over its outer peripheral surface. Depending on the location, there is a high possibility that there is no problem even if reading is performed to obtain shading data. Of course, if there is a white roller that has a shading data acquisition surface that is less likely to become dirty due to contact with the document and that is less likely to accumulate dirt even if it is dirty, shading can be eliminated while eliminating the above-mentioned disadvantages of poor cleaning performance. It can be said that there is a higher possibility that there is no problem even if reading is performed for data acquisition.

The present invention focuses on such a point, and when a target area of a predetermined width is read in order to obtain shading data for a white roller in a document moving type,
An image reading apparatus and shading data that can maintain the uniformity of the density of the shading data and read a high-quality document image by judging the degree of dirt in the target area and using the shading data as it is when there is no problem. The purpose is to provide a creation method.

In order to achieve the above-mentioned object, the degree of dirt in the read target area is determined, and emergency measures are appropriately performed in the event of a problem, so that the density uniformity of the shading data can be maintained. Provided are an image reading apparatus capable of reading a high-quality document image and a shading data creation method.

Further, in order to realize the above object, the position of the target area having a predetermined width for acquiring shading data can be changed to a place where dirt is as small as possible, and the density uniformity of shading data can be improved over a long period of time. An image reading apparatus and a shading data creation method capable of reading a document image of high quality that can be maintained in a high quality.

According to the present invention, a simple shape and easy-to-clean circular roller is used as the white roller in the original moving type.
It is an object of the present invention to provide an image reading apparatus and a shading data creation method capable of maintaining high density uniformity of shading data and reading a high-quality document image.

According to the present invention, it is preferable to use a white roller as a white roller of the original moving type, which has a preferable reading surface which is hardly stained by contact with the original and which is less likely to collect dirt even if it becomes dirty and which is easy to clean. It is an object of the present invention to provide an image reading apparatus and a shading data creation method capable of acquiring data from a surface, maintaining uniform density of shading data for a long period of time, and reading a high-quality document image. I do.

In order to achieve the above object, the present invention provides an image reading apparatus which has a plurality of preferable reading surfaces, increases the probability of obtaining good data without any trouble from the preferable reading surfaces, and has a high data obtaining efficiency. Provides a shading data creation method.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus which can appropriately cope with a case where a white roller in a document moving type is completely stained.

Still another object of the present invention is to provide an image forming apparatus or a facsimile apparatus capable of handling high-quality image data by using such an image reading apparatus.

[0017]

According to a first aspect of the present invention, there is provided an image reading apparatus in which a document transport path on which a document is transported and a reading position are set for the document transported on the document transport path. An image reading unit having a photoelectric conversion element that reads an image of the document, a white roller that is disposed opposite to the reading position of the image reading unit across the document conveyance path and is driven to rotate in the document conveyance direction by a driving source; Reading means for reading a target area of a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element, and comparing means for comparing comparison data based on read data in the target area read by the reading means with a reference value And a judging means for judging whether or not the degree of dirt in the target area is acceptable based on a result of the comparison by the comparing means. Shading data determining means for determining a value calculated using the read data in the target area as shading data, and an image of an original read by the photoelectric conversion means using the shading data determined by the shading data determining means And white shading correction means for correcting the data for white shading.

Accordingly, a target area of a predetermined width on the peripheral surface of the white roller is read for shading data generation. By comparing the target area with a certain reference value based on the read data, the degree of contamination of the target area can be tolerated. Judge whether or not
In particular, when it is acceptable without contamination, the value calculated using the read data of the target area is used as the shading data, so that the shading data becomes appropriate, and thus the density uniformity of the shading data can be maintained. It is possible to read a high-quality document image.

According to a second aspect of the present invention, an image reading apparatus reads an image of a document by setting a document transport path on which the document is transported and a reading position for the document transported on the document transport path. An image reading unit having a photoelectric conversion element, a white roller that is disposed to face the reading position of the image reading unit across the document conveyance path and is driven to rotate in the document conveyance direction by a driving source, and the photoelectric conversion element Reading means for reading the entire circumference including the target area having a predetermined width on the peripheral surface of the white roller; and an average value for each pixel of read data in the target area read by the reading means and read data for the entire circumference. Average value calculating means for calculating an average value of the entire circumference of each pixel, and the average value of the entire circumference of each pixel using the average value of each pixel calculated by the average value calculating means as a reference value. Compare Comparing means; determining means for determining whether or not the degree of dirt for each pixel in the target area is acceptable based on the result of comparison by the comparing means; Shading data determining means for determining the average value of pixels as shading data; and white shading correction for white shading correction of image data of the original read by the photoelectric conversion means using the shading data determined by the shading data determining means. Means,
Is provided.

Therefore, the target area of a predetermined width on the peripheral surface of the white roller is read for shading data generation, and the entire circumference is also read, and the average value of the read data in the target area for each pixel and the total circumference are read. It is determined whether the degree of dirt for each pixel of the target area is acceptable by calculating an average value of the entire circumference of each pixel of the read data and comparing the average value with the average value of the entire circumference. If the average value of the target area is higher than the average value of the entire circumference, the target area can be determined to be whitish and not particularly dirty than the other areas. Since the average value of the pixels is used as the shading data, the shading data becomes appropriate. Therefore, the density uniformity of the shading data can be maintained and a high-quality original image can be read.

According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the shading data determining means is configured to determine, when the result of the determination by the determining means is an unacceptable pixel, the entire circumference average value of the pixel. Is determined as shading data.

Therefore, when the average value of the pixel in the target area is lower than the average value in the entire circumference, the pixel portion in the target area is more contaminated than other areas in the sub-scanning direction. It can be determined that shading data is not suitable. However, if such shading data cannot be tolerated, the average value of the entire circumference on the peripheral surface of the pixel is used as shading data, and appropriate emergency using more preferable data is performed. This is a measure, and shading data can be determined without the need for processing such as reacquisition of data, and the processing can be shifted to the subsequent processing.

According to a fourth aspect of the present invention, in the image reading apparatus according to the second or third aspect, the reading means sets the reading of the entire circumference of the white roller based on the roller diameter of the white roller in advance. It is defined by the number of main scanning lines.

Therefore, it is possible to easily control the reading operation for acquiring data for the entire circumference of the white roller.

According to a fifth aspect of the present invention, in the image reading apparatus according to the second or third aspect, the reading means indicates a rotation period for one rotation of the white roller when reading the entire circumference of the white roller. It is defined by the gate signal.

Therefore, it is possible to easily control the reading operation for acquiring the data for the entire circumference of the white roller.

According to a sixth aspect of the present invention, an image reading apparatus is configured to set an original transport path along which an original is transported, and to set a reading position for the original transported along the original transport path to read an image of the original. An image reading unit having a photoelectric conversion element, a white roller that is disposed to face the reading position of the image reading unit across the document conveyance path and is driven to rotate in the document conveyance direction by a driving source, and the photoelectric conversion element Reading means for reading only a target area of a predetermined width on the peripheral surface of the white roller, and comparing means for comparing comparison data based on read data in the target area read by the reading means with a preset reference value Determining means for determining whether or not the degree of dirt in the target area is acceptable based on the result of comparison by the comparing means; and the result of determination by this determining means is acceptable. In this case, the value calculated using the read data in the target area is determined as shading data by the shading data determining means, and the shading data determined by the shading data determining means is read by the photoelectric conversion means. White shading correction means for correcting white shading of the image data of the document.

Therefore, only the target area of a predetermined width on the peripheral surface of the white roller is read to generate shading data. By comparing comparison data based on the read data with a preset reference value, the target area is read. It is determined whether or not the degree of dirt is acceptable. If the level is not dirt and is acceptable, the value calculated using the read data of the target area is used as the shading data. Thus, the density uniformity of the shading data can be maintained, and a high-quality document image can be read.

According to a seventh aspect of the present invention, in the image reading apparatus according to the sixth aspect, there is provided an average value calculating means for calculating an average value for each pixel of read data in the target area as comparison data, The means compares the average value of each pixel with the reference value, and the determining means determines whether or not the degree of contamination of each pixel in the target area is acceptable based on the comparison result by the comparing means, If the result of the determination is a permissible pixel, the shading data determination means determines the average value of the pixel as shading data.

Therefore, only the target area of a predetermined width on the peripheral surface of the white roller is read to form the shading data, and the average value of the read data for each pixel in the target area is compared with a preset reference value. To determine whether the degree of dirt for each pixel in the target area is acceptable,
When the average value of the pixel in the target area is higher than the reference value, the pixel portion of the target area can be determined to be whitish and not particularly dirty than other areas in the sub-scanning direction. When it is acceptable, the average value of the pixel in the target area is set as the shading data, so that the shading data becomes appropriate, so that the density uniformity of the shading data can be maintained.
A high-quality document image can be read. Further, since only the target area needs to be read, processing time and processing data can be reduced.

According to an eighth aspect of the present invention, in the image reading apparatus according to the seventh aspect, the shading data determining means sets the reference value which is set in advance when a result of the determination by the determining means is an unacceptable pixel. Is determined as shading data.

Therefore, when the average value of the pixel in the target area is lower than the reference value, the pixel portion of the target area is partially more contaminated than other areas in the sub-scanning direction, and It can be determined that it is not suitable for data acquisition, but if it is not acceptable in this way, by setting a preset reference value as shading data, appropriate emergency treatment using more preferable data is obtained, and data is acquired The shading data is determined without the need for processing such as re-execution, and the processing can be shifted to the subsequent processing.

According to a ninth aspect of the present invention, in the image reading apparatus according to the sixth aspect, the number of pixels having read data smaller than a preset level value for each main scanning line in the target area is compared with the comparison data. The comparing means compares the number of pixels counted for each main scanning line with the reference value, and the determining means determines each main scan in the target area based on a comparison result by the comparing means. The shading data determination means determines whether or not the degree of dirt for each line is acceptable. If the determination result is a permissible main scanning line, the shading data shading means shades the value calculated using the read data of the main scanning line. Determined as data.

Therefore, only the target area of a predetermined width on the peripheral surface of the white roller is read for generating the shading data, but the read data smaller than the level value set in advance for each main scanning line in the target area is obtained. The number of pixels is counted as comparison data, and by comparing the number of pixels counted for each main scanning line with a preset reference value, whether the degree of dirt for each main scanning line in the target area is acceptable? If the number of pixels that are read data smaller than the level value of the main scanning line in the target area is not larger than the reference value, the main scanning line portion of the target area is whitish and particularly dirty. Since it can be determined that the image data does not exist, in such a case, the value calculated using the read data of the main scanning line of the target area is shaded. Since such an over data becomes a proper shading data, thus, can maintain the density uniformity of the shading data, perform the reading of high-quality original image. Further, since only the target area needs to be read, processing time and processing data can be reduced.

According to a tenth aspect of the present invention, in the image reading apparatus according to the ninth aspect, the shading data determining means determines the data of the main scanning line when the result of the determination by the determining means is unacceptable. The level value previously set as is used.

Therefore, when the number of pixels that are read data smaller than the level value of the main scanning line in the target area is not larger than the reference value, the main scanning line portion of the target area is partially stained. Therefore, it can be determined that shading data is not suitable, but in the case where such shading data cannot be tolerated, a level value set in advance as the data of the main scanning line is used.
An appropriate first-aid treatment using more preferable data is obtained, and shading data can be determined without any processing such as reacquisition of data, and the processing can be shifted to the subsequent processing.

An image reading apparatus according to the eleventh aspect of the present invention is
A document transport path on which the document is transported, and an image reading unit having a photoelectric conversion element for reading an image of the document with a reading position set for the document transported on the document transport path;
A white roller that is disposed opposite to the reading position of the image reading unit across the document conveyance path and is driven to rotate in the document conveyance direction by a driving source, and has a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element. The reading means for reading an area including the target area and exceeding the target area is compared with the number of pixels which becomes read data smaller than a preset level value for each main scanning line for the read data read by the reading means. Counting means for counting as data; comparing means for comparing the number of pixels counted for each main scanning line by the counting means with a preset reference value; and a comparison result by the comparing means for each main scanning line. It is determined whether the degree of contamination is acceptable or not, and this determination processing is repeated until the allowable number of main scanning lines reaches a predetermined number. And a shading step of determining a value calculated using read data of the predetermined number of lines as shading data if the determination is repeated until the predetermined number of lines is reached and the determination result is acceptable. A data shading means for white shading correction of image data of the original read by the photoelectric conversion means using the shading data determined by the shading data determining means;

Therefore, a target area of a predetermined width on the peripheral surface of the white roller is read for shading data generation, and an area exceeding the target area is also read, and a level set in advance for each main scanning line is set. The number of pixels serving as read data smaller than the value is counted as comparison data, and the number of pixels counted for each main scanning line is compared with a preset reference value, so that the number of pixels for each main scanning line in the target area is determined. It is determined whether the degree of dirt is acceptable or not. If the number of pixels that become read data smaller than the level value of the main scan line in the target area is not larger than the reference value, the main scan of the target area is not performed. Since it can be determined that the line portion is whitish and not particularly dirty, the determination and determination process is repeated until the allowable number of main scanning lines reaches the predetermined number of lines. In a trouble free main scanning lines collected predetermined number of lines can be used to create shading data, it becomes a proper shading data, therefore,
The uniformity of the density of shading data can be maintained, and a high-quality document image can be read.

According to a twelfth aspect of the present invention, in the image reading apparatus according to any one of the first to eleventh aspects, the position of the target area is set to the peripheral surface of the white roller when the result of the determination by the determination means is not acceptable. A target area position moving means for moving the target area upward;

Therefore, if the target area is dirty and is not suitable for obtaining shading data, the position of the target area having a predetermined width for obtaining shading data is changed as much as possible by moving the position of the target area. , The density uniformity of the shading data can be maintained for a long time, and a high-quality document image can be read. In particular, by sequentially changing the location,
Ultimately, it is possible to converge so that a place with the least amount of dirt becomes the target area.

According to a thirteenth aspect of the present invention, in the image reading apparatus according to the twelfth aspect, the target area position moving means determines a position of the target area from the next time when an unacceptable determination result is obtained by the determination means. To move.

Therefore, it is possible to quickly cope with a case where the target area is dirty.

According to a fourteenth aspect of the present invention, in the image reading apparatus according to the twelfth aspect, the target area position moving means is configured to execute the target area from the next time when a result of the unacceptable determination is obtained by the determining means a predetermined number of times. Move the position of.

Therefore, it is possible to avoid a position shift of the target area due to an instantaneous dirt or the like.

According to a fifteenth aspect of the present invention, in the image reading apparatus according to any one of the twelfth to twelfth aspects, the target area position moving means moves the target area in order when the position of the target area is sequentially moved. Move by an angle that does not return to the position.

Therefore, the processing for specifying the target area as a clean place on the peripheral surface of the white roller becomes efficient without trying the unacceptable place again as the target area.

According to a sixteenth aspect of the present invention, in the image reading apparatus according to any one of the twelfth to fourteenth aspects, the target area position moving means sequentially moves the position of the target area by an uneven angle.

Therefore, the processing for specifying the target area as a clean place on the peripheral surface of the white roller becomes efficient without trying the unacceptable place again as the target area.

According to a seventeenth aspect of the present invention, in the image reading apparatus according to any one of the twelfth to sixteenth aspects, the result of the determination by the determination means that the determination is unacceptable is cumulatively monitored to remove dirt around the entire circumference of the white roller. There is provided an all-around dirt detecting means for detecting, and a warning means for issuing a warning when the dirt on the entire circumference of the white roller is detected by the all-around dirt detecting means.

Therefore, even if the movement of the target area as described above is repeated, the result of the determination of the degree of dirt on the target area becomes unacceptable, and if the white roller is completely dirty, a warning is issued by the warning means. Since it is emitted, appropriate measures such as cleaning and replacement of the white roller can be taken.

According to an eighteenth aspect of the present invention, in the image reading apparatus according to any one of the first to seventeenth aspects, the white roller is a perfect circular roller.

Therefore, even when the simplest and easy-to-clean perfect circle roller is used as the white roller, the density uniformity of shading data can be maintained and a high-quality original image can be read.

According to a nineteenth aspect of the present invention, in the image reading device according to any one of the first to seventeenth aspects, the white roller has a center of curvature on a straight line perpendicular to the roller axis on an outer peripheral surface thereof. This is a roller having a preferred reading surface formed of a curved surface located inside the locus of the maximum outer peripheral surface of the roller.

In the present invention and the following invention, with respect to the white roller, the “maximum outer peripheral surface locus” means a perfect circular outer peripheral surface of the roller without a suitable reading surface. The “curved surface” that forms a preferred reading surface may be a curved surface formed with a center of curvature on a straight line perpendicular to the roller axis of the reading roller, and may be a convex, concave, or flat surface. Good. In the case of the convex shape, it can be formed as a curved surface having a curvature larger than the roller curvature at the center of curvature located on a straight line perpendicular to the roller axis on the opposite side of the roller axis with respect to the curved surface. At this time, if the center of curvature is set to infinity, a flat surface is obtained. In the case of the concave shape, it can be formed as a curved surface having a center of curvature positioned outside the roller on a straight line perpendicular to the roller axis on the same side as the curved surface with respect to the roller axis.

Therefore, by using a white roller having a suitable reading surface of such a specific shape, the suitable reading surface is unlikely to come into contact with the original even when the original is repeatedly conveyed, so that it has a groove structure even if it becomes dirty. Since the dirt does not easily collect on the suitable reading surface and is easy to clean, the suitable reading surface can be maintained in a white state for a long period of time. Therefore, the density uniformity of the shading data is maintained at a higher level, and a high-quality document image can be read. Further, there is no problem that a shadow is caused due to a preferable reading surface when reading an actual document image.

According to a twentieth aspect of the present invention, in the image reading apparatus according to the nineteenth aspect, the predetermined width of the target area is set to be smaller than the width of the preferred reading surface.

Therefore, when the target area is located within the preferred reading surface, the density uniformity of the shading data can be maintained at a higher level.

According to a twenty-first aspect of the present invention, in the image reading apparatus of the nineteenth or twentieth aspect, the white roller has a plurality of the preferred reading surfaces on a peripheral surface.

Accordingly, there is a high possibility that the image is read with the preferred reading surface as the target area, and the density uniformity of the shading data can be maintained at a higher level.

According to a twenty-second aspect of the present invention, in the image reading apparatus of the twenty-first aspect, a plurality of the preferred reading surfaces are provided at equal intervals on a peripheral surface of the white roller.

Accordingly, there is a high possibility that the image is read with the preferable reading surface as the target area, and the uniformity of the density of the shading data can be maintained at a higher level. In particular, when the position of the target area is moved, by making the movement amount unequal, it is possible to increase the possibility of reading a suitable reading surface as the target area.

According to a twenty-third aspect of the present invention, in the image reading apparatus according to the twenty-first aspect, a plurality of the preferred reading surfaces are provided at uneven intervals on a peripheral surface of the white roller.

Accordingly, there is a high possibility that reading is performed with the preferred reading surface as a target area, and the uniformity of density of shading data can be maintained at a higher level. In particular, when the position of the target area is moved, it is possible to increase the possibility of reading a suitable reading surface as the target area even when the movement amount is equalized.

According to a twenty-fourth aspect of the present invention, in the image reading apparatus of the eleventh aspect, the white roller has a center of curvature on a straight line perpendicular to the roller axis on an outer circumferential surface thereof, and has a maximum outer circumferential surface of the roller. A plurality of preferred reading surfaces formed of curved surfaces located inside the trajectory are provided on the peripheral surface at equal intervals, and the reading unit sets a range of an angle obtained by equally dividing the entire circumference by at least the number of the preferred reading surfaces. Read.

Therefore, in order to realize the invention according to claim 11, the read data portion (one suitable read surface alone or two suitable read surfaces) must be included in the read region while keeping the read region as small as possible. (A state across the surfaces) is included, and it is ensured that a predetermined number of main scan line read data that can be used for generating shading data is secured, and the density uniformity of shading data can be maintained at a higher level.

According to a twenty-fifth aspect of the present invention, in the image reading device according to any one of the first to twenty-fourth aspects, the image reading section is a contact type image sensor in which the photoelectric conversion element itself is arranged at the reading position. is there.

Accordingly, the present invention can be suitably applied to an original reading type image reading apparatus in which the photoelectric conversion element itself is large, but the overall configuration is small.

According to a twenty-sixth aspect of the present invention, in the image reading device according to any one of the first to twenty-fourth aspects, the image reading section reads out optical information at the reading position by forming a reduced image on the photoelectric conversion element. Includes reduction optics.

Accordingly, although a relatively large reduction optical system is required and the overall configuration is likely to be large, the present invention can be suitably applied to an original moving image reading apparatus which requires only a small photoelectric conversion element.

An image forming apparatus according to a twenty-seventh aspect of the present invention
An image reading apparatus according to any one of claims 1 to 26, wherein an image is formed on a recording medium based on image data of a document read by the image reading apparatus.

Therefore, the image reading apparatus according to any one of claims 1 to 26 is provided, and handles image data of a document corrected by using highly reliable shading data. An image forming apparatus that can be formed can be provided.

A facsimile apparatus according to a twenty-eighth aspect of the present invention includes the image reading device according to any one of the first to twenty-sixth aspects, and transmits image data of a document read by the image reading apparatus via a communication network. Output first.

Accordingly, the image reading apparatus according to any one of claims 1 to 26 is provided, and handles image data of a document corrected by using highly reliable shading data. A facsimile apparatus capable of transmitting and outputting can be provided.

According to a twenty-ninth aspect of the present invention, there is provided the shading data generating method, wherein the photoelectric conversion element of the image reading unit in which the reading position is set for the original conveyed on the original conveying path is sandwiched between the original conveying path. A reading step of reading the entire circumference including the target area of a predetermined width on the peripheral surface of the white roller disposed opposite to the reading position, and an average value for each pixel of read data in the target area read in the reading step; An average value calculating step of calculating an average value of the entire circumference of each pixel of the read data for the entire circumference, and the average value of each pixel calculated in the average value calculating step is the average value of the entire circumference of each pixel. A determination step of determining whether or not the degree of contamination of each pixel in the target area is acceptable based on the comparison result of the comparison step; and The case and a shading data determination step of determining the average value of the pixel as shading data.

Accordingly, the target area of a predetermined width on the peripheral surface of the white roller is read for shading data generation, and the entire circumference is also read, and the average value of the read data in the target area for each pixel and the total circumference are read. It is determined whether the degree of dirt for each pixel of the target area is acceptable by calculating an average value of the entire circumference of each pixel of the read data and comparing the average value with the average value of the entire circumference. If the average value of the target area is higher than the average value of the entire circumference, the target area can be determined to be whitish and not particularly dirty than the other areas. Since the average value of the pixel is used as the shading data, the shading data becomes appropriate, and thus the density uniformity of the shading data can be maintained.

According to a thirtieth aspect of the present invention, in the shading data creation method according to the twenty-ninth aspect, the shading data determining step includes the step of: determining, when the result of the determination in the determining step is an unacceptable pixel, the entire circumference of the pixel; Determine the value as shading data.

Therefore, when the average value of the pixel in the target area is lower than the average value in the entire circumference, the pixel portion in the target area is more contaminated than other areas in the sub-scanning direction. It can be determined that shading data is not suitable. However, if such shading data cannot be tolerated, the average value of the entire circumference on the peripheral surface of the pixel is used as shading data, and appropriate emergency using more preferable data is performed. This is a measure, and the shading data can be determined without requiring processing such as reacquisition of data.

According to a thirty-first aspect of the present invention, there is provided the shading data creating method, wherein the photoelectric conversion element of the image reading section in which the reading position is set for the original conveyed on the original conveying path is sandwiched between the original conveying path. A reading step of reading only a target area of a predetermined width on the peripheral surface of the white roller opposed to the reading position, and an average for calculating an average value for each pixel of read data in the target area read in the reading step A value calculating step, a comparing step of comparing the average value of each pixel calculated in the average value calculating step with a preset reference value, and a comparison result of the comparing step for each pixel in the target area. A determining step of determining whether or not the degree of contamination of the pixel is acceptable; and, for a pixel for which the determination result in the determining step is allowable, the average value of the pixel is determined by shading data. And a shading data determination step of determining by.

Therefore, only the target area of a predetermined width on the peripheral surface of the white roller is read in order to generate shading data. The average value of the read data in each pixel of the target area is compared with a preset reference value. To determine whether the degree of dirt for each pixel in the target area is acceptable,
When the average value of the pixel in the target area is higher than the reference value, the pixel portion of the target area can be determined to be whitish and not particularly dirty than other areas in the sub-scanning direction. In this case, the average value of the pixel in the target area is used as the shading data, so that the shading data becomes appropriate. Therefore, the density uniformity of the shading data can be maintained. Further, since only the target area needs to be read, processing time and processing data can be reduced.

According to a thirty-second aspect of the present invention, in the shading data creating method according to the thirty-first aspect, the shading data determining step is performed in a case where the judgment result in the judging step is an unacceptable pixel. The value is determined as the shading data of the pixel.

Accordingly, when the average value of the pixel in the target area is lower than the reference value, the pixel portion of the target area is partially more contaminated than other areas in the sub-scanning direction, and It can be determined that it is not suitable for data acquisition, but if it is not acceptable in this way, by setting a preset reference value as shading data, appropriate emergency treatment using more preferable data is obtained, and data is acquired The shading data can be determined without the need for processing such as redoing.

The shading data generating method according to the invention is preferably arranged such that a photoelectric conversion element of an image reading section in which a reading position is set for a document conveyed on the document conveying path is sandwiched between the document conveying path. A reading step of reading only a target area of a predetermined width on the peripheral surface of the white roller opposed to the reading position; and a level value set in advance for each main scanning line in the target area read in the reading step. A counting step of counting the number of pixels that also result in small read data, a comparing step of comparing the number of pixels counted for each main scanning line by the counting step with a preset reference value, and a comparison of the comparing step. A determining step of determining whether the degree of dirt for each main scanning line in the target area is allowable based on the result; and a main scanning in which the determination result in the determining step is allowable. And shading data determination step of determining a value calculated by using the read data of the main scanning line as shading data in the case of in,
Is provided.

Therefore, only the target area of a predetermined width on the peripheral surface of the white roller is read for generating the shading data, but the read data smaller than the level value preset for each main scanning line in the target area is read. The number of pixels is counted as comparison data, and by comparing the number of pixels counted for each main scanning line with a preset reference value, whether the degree of dirt for each main scanning line in the target area is acceptable? If the number of pixels that are read data smaller than the level value of the main scanning line in the target area is not larger than the reference value, the main scanning line portion of the target area is whitish and particularly dirty. Since it can be determined that the image data does not exist, in such a case, the value calculated using the read data of the main scanning line of the target area is shaded. Since such an over data becomes a proper shading data, thus, it can maintain the density uniformity of the shading data. Further, since only the target area needs to be read, processing time and processing data can be reduced.

According to a thirty-fourth aspect of the present invention, in the shading data creation method according to the thirty-second aspect, the shading data determining step is set in advance when the result of the determination in the main scanning line is unacceptable. A value calculated using the level value is determined as shading data.

Therefore, if the number of pixels that are read data smaller than the level value of the main scanning line in the target area is not larger than the reference value, the main scanning line portion of the target area is partially stained. Therefore, it can be determined that shading data is not suitable, but in the case where such shading data cannot be tolerated, a level value set in advance as the data of the main scanning line is used.
An appropriate first-aid treatment using more preferable data is obtained, and shading data can be determined without requiring processing such as reacquisition of data.

According to a thirty-fifth aspect of the present invention, in the shading data creating method according to any one of the thirty-ninth to thirty-fourth aspects, if the result of the determination in the determining step is not acceptable, the position of the target area is changed to the circumference of the white roller. And moving the target area on the surface.

Therefore, when the target area is dirty and is not suitable for obtaining shading data, the position of the target area having a predetermined width for obtaining shading data is moved as much as possible by moving the position of the target area. , The density uniformity of the shading data can be maintained for a long time, and a high-quality document image can be read. In particular, by sequentially changing the location,
Ultimately, it is possible to converge so that a place with the least amount of dirt becomes the target area.

According to a thirty-sixth aspect of the present invention, there is provided the shading data generating method, wherein the photoelectric conversion element of the image reading unit in which the reading position is set with respect to the original conveyed on the original conveying path, sandwiches the original conveying path. A reading step of reading an area including a target area of a predetermined width on the peripheral surface of the white roller opposed to the reading position and reading an area exceeding the target area; and setting read data read in the reading step for each main scanning line in advance. A counting step of counting the number of pixels that become read data smaller than the level value that has been set, and a comparing step of comparing the number of pixels counted for each main scanning line by the counting step with a preset reference value. It is determined whether or not the degree of dirt for each main scanning line is an acceptable level based on the comparison result in this comparison step, and the main run which can accept this determination processing is determined. A determination step repeated until the number of lines reaches the predetermined number of lines; and a determination process in this determination step is repeated until the number of lines reaches the predetermined number of lines. A shading data determining step of determining the determined value as shading data.

Therefore, a target area having a predetermined width on the peripheral surface of the white roller is read for shading data generation. In addition, an area beyond the target area is also read, and a predetermined level is set for each main scanning line. The number of pixels serving as read data smaller than the value is counted as comparison data, and the number of pixels counted for each main scanning line is compared with a preset reference value, so that the number of pixels for each main scanning line in the target area is determined. It is determined whether the degree of dirt is acceptable or not. If the number of pixels that become read data smaller than the level value of the main scan line in the target area is not larger than the reference value, the main scan of the target area is not performed. Since it can be determined that the line portion is whitish and not particularly dirty, the determination and determination process is repeated until the allowable number of main scanning lines reaches the predetermined number of lines. In a trouble free main scanning lines collected predetermined number of lines can be used to create shading data, it becomes a proper shading data, therefore,
The density uniformity of shading data can be maintained.

According to a thirty-seventh aspect of the present invention, in the shading data creating method according to any one of the thirty-sixth to thirty-sixth aspects, the white roller to be read in the reading step has an outer peripheral surface perpendicular to the roller axis. A roller having a preferred reading surface formed of a curved surface having a center of curvature on a straight line and located inside the locus of the maximum outer peripheral surface of the roller is used.

Therefore, by using a white roller having a preferable reading surface of such a specific shape, the preferable reading surface is unlikely to be in contact with the original even when the original is conveyed repeatedly, so that it has a groove structure even if it becomes dirty. Since the dirt does not easily collect on the suitable reading surface and is easy to clean, the suitable reading surface can be maintained in a white state for a long period of time. Therefore, the density uniformity of the shading data can be maintained at a higher level.

[0092]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. The present embodiment is applied to a digital copying machine as an image forming apparatus, and FIG. 1 is a vertical sectional front view showing a schematic structure of the digital copying machine. This digital copier includes a scanner 1 as an image reading apparatus having a double-sided reading function, and a paper 2 based on image data read by the scanner 1 by electrophotography.
And a printer 2 for forming an image on the printer.

The scanner 1 has a so-called ADF structure, and includes a first image reading section 3, a second image reading section 4, a document setting section 5, a document discharge section 6, a document transport path 7, a large number of transport rollers. 8, a first contact glass 9, a second contact glass 10, a first reading roller 11, a second reading roller 12, and the like.

A document D to be read (see FIG. 3) is set in the document setting section 5, and a document D from which an image has been read is discharged to a document discharge section 6. The document transport path 7 is a path provided between the document setting section 5 and the document discharge section 6, and transports the document D from which an image is read one by one. When reading the document D, the mode is switched so that the first image reading unit 3 is used when the document D is a single-sided document.
Only when the original D is a double-sided original, the first image reading unit 3 and the second image reading unit 4 read the image.

The first image reading section 3 can read the image of the document D fixedly placed on the contact glass 9 by a photoelectric conversion element, for example, a CCD 3a. 11 (that is, on the document transport path 7). When the document D conveyed on the document conveyance path 7 is read, the reading roller 11 is driven to rotate at the same speed as the conveyance roller 8 by a driving stepping motor (not shown), and the conveyed document D is conveyed. Contact glass 1
Acts to press against zero.

The second image reading section 4 serving as the image reading section of the present embodiment moves the CCD 42 (see FIG. 5), which is a photoelectric conversion element, to the reading position P of the document D conveyed on the document conveying path 7. Contact image sensor (CI
With the S) configuration, the image of the document D (backside image) conveyed on the document conveyance path 7 can be read by the CCD 42. The second reading roller 12 as a white roller is disposed to face the reading position P of the image reading unit 4 with the document conveying path 7 interposed therebetween. When reading the document D by the image reading unit 4, the reading roller 12 The reading roller 26 is driven at the same speed as the conveyance roller 8 by a reading motor 26 (see FIG. 4) using a stepping motor as a driving source, and acts so as to keep the distance between the image surface of the document D and the image reading section 4 constant.

The printer 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 image reading unit 3 or 4 is written on the surface of the photoconductor 14 by the laser unit 15, and the electrostatic latent An image is formed. The electrostatic latent image is visualized as a toner image by supplying toner from the developing device 16, and the visualized toner image is recorded by the transfer device 17 and fed from the paper feed cassette 19. The image is transferred onto a sheet 20 as a medium. The sheet 20 to which the toner image has been transferred is subjected to a fixing process by the fixing device 18 and then discharged to a discharge tray 21.

FIG. 2 shows the second reading roller 12 used in the copying machine of the present embodiment and the original transport path 7 before and after the second reading roller 12.
FIG. 3 is an enlarged front view showing the reading roller 12.

As shown in FIGS. 2 and 3, the reading roller 1
Numeral 2 is disposed opposite to the reading position P where the CCD 42 of the close contact type image sensor constituting the image reading unit 4 is located, and is formed in a substantially circular cross-sectional shape. It is formed white in color. A part of the outer peripheral surface of the reading roller 12 includes the reading roller 1
A preferred reading surface 13 extending along the direction of the axis 2 is formed. As shown in FIG. 3, the preferred reading surface 13 has a center of curvature B on a straight line a perpendicular to the axis A of the reading roller 12 and at a position different from the axis A. Outer peripheral surface locus (the substantially circular outer peripheral surface of the reading roller 12 without the suitable reading surface 13 and a portion indicated by a solid line and a dashed line) located at an inner side of C and indicated by a solid line It is formed with a curved surface shape that is smoothly continuous with the outer peripheral surface.

However, the shape of the preferred reading surface 13 can take various shapes. For example, in the example shown in FIG. 3, since the center of curvature B is located on the opposite side of the preferred reading surface 13 with respect to the axis A, it is formed as a convex curved surface when viewed from the axis A side. I have. On the other hand, the curvature center B is set at a position outside the reading roller 12 on the same side as the preferred reading surface 13 with respect to the axis A, and is formed as a concave curved surface when viewed from the axis A side. Is also good. In this case, the preferred reading surface 1
Since the connection between 3 and the maximum outer peripheral surface is slightly sharper,
It is preferable to perform chamfering so as to be smoothly continuous. Incidentally, the example shown in FIG. 2 is based on the assumption that the center of curvature B is set to infinity in the example shown in FIG. 3, and the preferred reading surface 13 is formed in a shape where the curved surface is flat. (In the following description, a flat reading surface formed as shown in FIG. 2 will be used as a representative example as the preferred reading surface 13).

FIG. 4 is a schematic block diagram showing the electrical connection of the control system of the copying machine according to the present embodiment. In this control system, the main body control unit 22 includes a CPU, a ROM, and a RAM.
And controls the entire copying machine. The controller 23 is also a CPU, RO
M, RAM, etc.
Various motors related to conveyance / discharge, such as a pickup motor 24, a paper feed motor 25, a reading motor 26, a discharge motor 27, a bottom plate raising motor 28, and the like, are connected. Various sensors related to operation control, timing control, and the like of sheet feeding, conveyance, and sheet discharge, that is,
A registration sensor 29, a document set sensor 30, a paper discharge sensor 31, an abutment sensor 32, a document width sensor 33, a reading entrance sensor 34, a table elevation sensor 35, a bottom plate home position sensor 36, and the like are connected. Control. The operation unit 38 is provided with various keys for instructing and displaying various operations of the copying machine and an LCD display.

The controller 23 is also connected to the second image reading section 4, and the image data read by the image reading section 4 is transferred and output to the main body control section 22 (the controller 23 outputs the image data to the controller 23). One image reading unit 3 is also connected, but illustration and description are omitted).

FIG. 5 is a schematic block diagram showing a control system for the electrical hardware configuration inside the second image reading section 4. In the image reading section 4, the light from the light source 41 illuminated by the lighting signal from the controller 23 is irradiated on the document D in a slit shape at the reading position P, so that the reflected light from the reading position P of the document D is generated. C composed of many sensor chips via a rod lens (not shown)
The image is condensed and formed on the CD 42, and the original image is read. The reading of the actual document image is started by the gate signal XSFGATE (described later) from the controller 23 at the timing when the leading edge of the document D reaches the reading position P, and the reading of the image of the document D is started for each line obtained sequentially. The image data is temporarily stored in a frame memory 46 via an amplifier 43, an A / D conversion circuit 44, and an image processing circuit 45. After that, the main controller 2 is controlled via the output control circuit 47 and the I / F circuit 48.
2 to transfer and output the image data.

The image data obtained by reading the front side of the document D transferred and output to the main body control section 22 is transferred to the main body image processing circuit 39 under the control of the main body control section 22.

In such a configuration, in the copying machine according to the present embodiment, when the double-sided copy mode is selected, the original D set in the original set unit 5 with the front side facing upward is set.
Are transported one by one on the document transport path 7, the first image reading unit 3 reads an image on the front side, and the second image reading unit 4
To read the image on the back side. The image data read by these first and second image reading units 3 and 4 is
The toner image is formed on the front side and the back side of the same sheet 20 by the image forming process in the printer 2, and the two-sided copy is performed.

In the copying machine according to the present embodiment, the image data read from the original D is subjected to various image processing such as black shading correction, white shading correction, and γ correction in the main body image processing circuit 39 described above. Will be applied.
In the case of the second image reading unit 4, the generation of the shading data used for the white shading correction in this case is performed by reading the reading roller 12 arranged opposite to the reading position P by the CCD.

Hereinafter, the creation of the shading data for white shading correction will be described. As shown in the timing chart of FIG. 6, during the period when the gate signal XSFGATE indicating the reading period of the document D is not active (document area = L level), that is, while the document D is not at the reading position P, the shading data Becomes active (shading area) for a predetermined width w1 in the circumferential direction of the reading roller 12 during the active period, and the outer peripheral surface of the reading roller 12 is read by the CCD 42 for a plurality of lines during the active period to perform shading. Obtain read data to generate data. That is, the controller 23 causes the CCD 42 to read the target area 50 having the predetermined width w1 of the reading roller 12 by outputting the gate signal XSHGATE at a predetermined timing. Thereby, an original reading means or reading step is realized. The predetermined width w1 in this case is a length corresponding to the central angle θ of the reading roller 12 as shown in FIG.
Assuming that the width of the preferred reading surface 13 is w2, it is set such that w1 <w2. In addition, the predetermined width w1 is the CCD4
The number of read lines by 2 is set to a width corresponding to L lines. The timing at which the gate signal XSHGATE becomes active is managed to be at a specific position by a pulse counter (not shown) that defines the number of pulses of the reading motor 26 that rotates the reading roller 12 in the controller 23.

Here, in the present embodiment, as shown in FIG. 6, during the period when the gate signal XSFGATE indicating the reading period of the document D is not active (document area = L level), the peripheral surface of the reading roller 12 is moved. The target area 50 corresponding to the predetermined width w1 = L lines is read and the entire circumference of the reading roller 12 is also read, and the degree of contamination of the target area 50 is determined based on the read data of the entire circumference. , Target area 5
A determination is made as to whether the read data of 0 can be used for shading data.

For this reason, in the present embodiment, the predetermined width w1
In addition to the reading operation of the target area 50 for the = L lines, the reading operation for the entire circumference of the reading roller 12 is also required.
As shown in the figure, the number of lines for one round preset from the roller diameter of the reading roller 12 may be defined by M lines,
Alternatively, it may be defined by using a gate signal SHGATE2 indicating one rotation of the reading roller 12 together with the gate signal SHGATE1 for the target area 50. In any case, it can be easily controlled by the controller 23.

FIG. 8 shows the main image processing circuit 39
FIG. 3 is a schematic block diagram illustrating a circuit configuration for performing white shading correction. This circuit includes a shading data creation circuit 51 and a shading operation circuit 52 as white shading correction means. The shading data creation circuit 51 includes an L-line averaging circuit 53 as an average value calculation unit to which image data of L lines of the target area 50 is input, and an average to which image data of M lines including the target area 50 are input. It comprises a one-round averaging circuit 54 as a value calculating means, and a comparing means 55 for comparing the outputs of these averaging circuits 53 and 54, a determining means and a shading data determining means.

In such a configuration, the controller 2
Referring to the schematic flow chart shown in FIG. 10 managed by the step S3, after the rotation of the reading motor 26 starts (step S1), the gate signal XSHGATE managed by the pulse counter becomes active during the period when the gate signal XSFGATE is not active. (Y in S2), the gate signals SHGATE1 and SHGATE2 both become active (asserted) as shown in FIG. 9 (S3), and the CCD 42 moves the peripheral surface of the reading roller 12 by 1 (see FIG. 9). The reading is performed sequentially line by line. The reading area in this case is the target area 50, and a reading unit and a reading step are realized by this processing. The read data in this case is also input to the one-round averaging circuit 54, but is sequentially input to the L-line averaging circuit 53, and an average value calculation process for obtaining an average value for each pixel for the read data for the L lines is performed. (S4). By the processing in step S4, an average value calculating means and an average value calculating step are realized. The average value in this case is calculated as a simple average value, but may be a multiple addition average value or the like.

L lines (center angle θ = predetermined width w1)
When the reading process of (minute) is completed, the gate signal SHGATE1 becomes non-active (negated) (S5), but the gate signal SHGATE2 remains active (asserted).
Subsequently, the CCD 42 sequentially reads the peripheral surface of the reading roller 12 line by line. By this processing, reading means and a reading step for the entire circumference of the reading roller 12 are realized. The read data in this case is sequentially input to the one-circle averaging circuit 54, and an average value calculation process for obtaining a full-circle average value for each pixel is performed on the read data for the entire circumference = M lines (S6). The processing in step S6 implements an average value calculation unit and an average value calculation step. In this case, the entire circumference average value is calculated as a simple average value, but may be a multiple addition average value or the like. When the reading process for the M lines (for the entire circumference) is completed, the gate signal SHGATE2 also becomes non-active (negated) (S7), and the reading operation of the reading roller 12 by the CCD 42 ends.

The L-line average value calculated by the L-line averaging circuit 53, which is the average value for each pixel, and the all-round average value calculated for each pixel, calculated by the one-round averaging circuit 54, are compared with a comparison judgment circuit. 55 is input. In this comparison determination circuit 55,
By comparing the magnitude relationship between the two values using the entire circumference average value as a reference value and the L line average value as comparison data for each pixel,
The process of determining whether or not the L-line average value can be used as shading data is performed as a process of determining the degree of contamination and a process of determining shading data for the target region 50 (described later with reference to the following specific examples). In this case, the shading data for each pixel is determined, and the determined shading data is output to the shading arithmetic circuit 52 and stored in a memory (not shown) in the shading arithmetic circuit 52.

The shading data for each pixel stored in the memory is used for white shading correction at the time of reading an actual original image (S13). That is, in the shading operation circuit 52, when reading an original image, the image data is directly input sequentially for each line.
The image data for each pixel is subjected to white shading correction using the shading data for each pixel obtained from the memory, and is output to a subsequent processing circuit. When the reading operation for the original is completed, the rotation of the reading motor 26 also stops (S
14) Stand by for the next document reading operation.

The above processing is specifically described as follows.

First, the L line averaging circuit 53 and the step S
The average value of the L line, which is the average value of the data for the L lines in step 4, is calculated by the equation (1), the one-round average circuit 54,
The average value of the entire circumference of the data for M lines is obtained by the calculation of equation (2).

Dsg (n) = INT [ΣD (n) / L] (1) Drl (n) = INT [ΣD ′ (n) / M]... ... (2) Dsg (n): calculation data of the n-th pixel in the target area 50 =
L-line average value Drl (n): calculated data of the n-th pixel for the entire circumference of the reading roller 12 = average value of the entire circumference D (n): read data of the n-th pixel ΣD (n): one line of D (n) Addition value from the first line to the Lth line ΣD ′ (n): Addition value for one round (M lines) of reading roller 12 of D (n) L: Number of lines in target area 50 M: One of reading roller 12 Number of lines for circumference INT []: Round off to the nearest decimal point

In order to generate shading data Dp (n) for each pixel from each average value, the shading data Dp (n) is calculated by equations (3) and (4). Dsg (n) ≧ Drl (n) Dp (n) = Dsg (n) (3) Dsg (n) <Drl (n) Dp (n) = Drl (n)) …………………… (4)

That is, the reading roller 12 is read, and the L line average value Dsg (n) and the perimeter average value Drl (n) are calculated for each pixel, and then the L line average value Dsg (n) for each pixel is calculated. Is compared with the perimeter average value Drl (n) for each pixel (S8). By the processing in step S8, a comparing unit and a comparing step are realized. Further, the processing in step S8 implements a determination unit and a determination step of determining whether or not the degree of dirt for each pixel in the target area 50 is acceptable.
If Dsg (n) ≧ Drl (n) (Y in S8), the target area 50 is whiter than the other areas in the reading roller 12 at the same position in the sub-scanning direction, is less contaminated, and is acceptable for shading data acquisition. This means a determination result indicating that it is possible, and the L line average value Dsg (n) based on the read data of the target area 50 is directly determined as shading data (S9). The processing in step S9 is realized as shading data determination means and a shading data determination step.

On the other hand, when Dsg (n) <Drl (n), (S
8N), meaning that the target area 50 on the same position in the sub-scanning direction on the reading roller 12 is partially soiled more than other areas and is not suitable for shading data acquisition. The average value Dsg for the shading data
The average value Drl (n), which is more preferable than (n), is determined as shading data (S10). This step S1
0 is realized as shading data determination means and shading data determination step.

The calculation of the white shading correction is performed by the equation (5) (when the image data is handled by 8 bits). Dsh = (D (n) / Dp (n)) × 255 (5)

In the present embodiment, the target area 5
Even if the average value Dsg (n) of a certain pixel of 0 is one, the entire circumference average value D
If the value is lower than rl (n) and it is determined that the pixel is unacceptable (N in S8), the shading data of the pixel is determined to be the entire circumference average value Drl (n) as described above. At the same time (S10), the pulse counter value for the reading motor 26 is changed so as to move the position of the target area 50 at the time of acquiring the next shading data (S10).
11). Specifically, as shown in FIG.
The next position of the target area is (θ +
α) is set to move by an angle. In this case, the angle α is smaller than the angle θ and is a variable angle,
That is, it is preferable that the angle of (θ + α) is unequal, and is set to a value such that it does not return to the original position even after one rotation on the reading roller 12. In any case, the motor pulse corresponding to the angle (θ + α)
It is calculated by Step S when reading the next document
By monitoring the pulse counter value updated in the process 2, the process of moving the target position on the reading roller 12 is realized as a target region position moving unit and a target region position moving step.

In the present embodiment, the L-line average value Dsg (n) of a certain pixel in the target area 50 is lower than the entire-circumference average value Drl (n), and is not acceptable. Is determined (N in S8), the position of the next target area is immediately moved so that the target area 50 can be quickly dealt with when it is dirty.
(n) The number of times that <Drl (n) is counted, and after the counted value reaches a predetermined number of times, the pulse counter value for the reading motor 26 is changed to move the position of the target area 50. You may. According to this, it is possible to avoid a position shift of the target area 50 due to instantaneous dirt or the like that recovers immediately.

Therefore, according to the present embodiment, the target area 50 having the predetermined width w1 on the peripheral surface of the reading roller 12 is read for shading data generation. The average value Dsg (n) of the L-line for each pixel of the read data and the average value Drl (n) of the full-circle for each pixel of the read data for the entire circumference are calculated.
Is compared with the entire circumference average value Dsg (n) to obtain the target area 5
It is determined whether the degree of dirt for each pixel of 0 is acceptable (whether or not the target area 50 is set in a clean place on the reading roller 12), and the L line average value Dsg ( If n) is higher than the entire circumference average value Dsg (n), it can be determined that the target area 50 is whitish and not particularly dirty than the other areas. By using the L-line average value Dsg (n) of the pixel in the area 50 as shading data, appropriate shading data can be obtained. Therefore, uniform density of shading data can be maintained and high-quality original image reading can be performed. Becomes On the other hand, if the L-line average value Dsg (n) of the pixel in the target area 50 is lower than the entire-circumference average value Drl (n), the pixel portion of the target area 50 is not in the sub-scanning direction. It can be determined that the area is more dirty than the area and is not suitable for obtaining shading data. However, in the case where such an area cannot be tolerated, the entire circumference average value Drl (n) on the peripheral surface of the pixel is determined as shading data. By doing so, appropriate first-aid treatment using more preferable data is performed, and shading data can be determined without the need for processing such as reacquisition of data, and the processing can be shifted to the subsequent processing.

If the target area 50 is determined to be dirty and is not suitable for obtaining shading data, the position of the target area 50 is moved at the next data acquisition. The position of the target area 50 having a predetermined width can be changed to a place with as little dirt as possible, the uniformity of density of shading data can be maintained for a long time, and a high-quality document image can be read.

Therefore, even when the simplest and easy-to-clean perfect-circle roller (not shown) is used as the reading roller (white roller), the entire surface is generally soiled from the beginning. It can be understood that the reading roller 12 is effective because
According to this, the preferred reading surface 13 is less likely to be soiled because it is difficult to contact the original D even when the original is transported repeatedly, and even if it is dirty, it does not have a groove structure. , The suitable reading surface 13 can be maintained in a white state for a long period of time. Further, even when reading the actual document image, the reading roller 12 does not have a groove structure, so that there is no problem that the suitable reading surface 13 causes a shadow. As a result, such a preferable reading surface 13
May be read as the position of the target area 50,
This is advantageous in maintaining the density uniformity of shading data at a high level. In particular, since the predetermined width w1 of the target area 50 is smaller than the width w2 of the preferred reading surface 13, the target area 50
Is more likely to be completely located within the preferred reading surface 13,
This is preferable for maintaining the density uniformity of shading data at a higher level. Furthermore, when the position of the target area 50 is sequentially moved, the position of the target area 50 can be finally converged so as to be always on the preferable reading surface 13 with the least stain. At this time, by appropriately setting the amount of movement for each time, the unacceptable place is not tried again as the target area 50, and the target area 50 is not stained on the peripheral surface of the reading roller 12, especially the suitable reading. Processing for specifying the surface 13 becomes efficient.

In this regard, as shown in FIG.
For example, if the reading roller 12 having three suitable reading surfaces 13a, 13b, and 13c is used, the target area 50 is positioned on the preferable reading surface 13a, 13b, or 13c.
Alternatively, the possibility of convergence can be increased. When the preferred reading surfaces 13a, 13b, and 13c are arranged at equal intervals, the amount of movement for moving the position of the target area 50 may be made uneven, but as shown in FIG. When the surfaces 13a, 13b, and 13c are arranged unevenly, any one of the preferable reading surfaces 13a, 13b, or 1 can be used even if the movement amount for moving the position of the target area 50 is constant.
It becomes easy to converge the position of the target area 50 to 3c.

By the way, in the present embodiment, even one L line average value Dsg (n) of a certain pixel in the target area 50 becomes lower than the entire circumference average value Drl (n). When it is determined that it is not permissible (N in S8), the number is counted each time by the SHNG counter in the controller 23 (S12). The SHNG counter is used to detect dirt over the entire circumference of the reading roller 12 by cumulatively monitoring the number of negative determination results in step S8.
As shown in the flowchart of FIG. 11, it is always monitored whether or not the count value of the SHNG counter has reached a preset specified value J (S21). When the count value of the SHNG counter reaches the specified value J (Y in S21), the value of the abnormality detection counter is incremented by 1 (S22), and if the value of the abnormality detection counter is smaller than 3 (S23).
(Y), a warning display for prompting replacement or cleaning of the reading roller 12 is displayed on the LCD display unit of the operation unit 38 of the scanner 1 (S24). By the processing of Y and S22 in step S21, an all-around dirt detecting means is realized,
Warning processing is realized by the processing of step S24. Accordingly, it is possible to appropriately cope with a case where the reading roller 12 is finally completely soiled and there is no longer any place that can be appropriately set as the target area 50. In the case of the reading roller 12 having the preferred reading surface 13 of a specific shape as in the present embodiment, such a situation is unlikely to occur, but it is particularly effective when a perfect circular white roller is used. It is.

When the value of the abnormality detection counter exceeds 3 (N in S23), the fact that there is an abnormality in the image reading section 4 (CIS) in the operation section 38 of the scanner 1 is indicated. A warning is displayed through the LCD display.

A second embodiment of the present invention will be described with reference to FIGS. Parts that are the same as or correspond to the parts shown in the first embodiment are denoted by the same reference numerals,
The description is also omitted (the same applies to the following embodiments).

In the above-described embodiment, the entire circumference of the reading roller 12 is read together with the target area 50. However, in the present embodiment, as shown in FIG. Is basically read. Then, an average value for L lines is calculated for each pixel as comparison data based on the read data in the target area 50, and the average value for each pixel is compared with a preset reference value, thereby obtaining the target data. The degree of dirt in the area 50, particularly the degree of local dirt in the sub-scanning direction, is determined, and if it is determined that there is no or little dirt, the calculated average value is directly handled as shading data. It was made.

FIG. 14 is a schematic block diagram showing a circuit configuration for performing white shading correction included in the main body image processing circuit 39 of the present embodiment. This circuit includes a shading data creation circuit 61 and a shading operation circuit 62 as white shading correction means. The shading data creation circuit 61 receives an image data for L lines of the target area 50 and calculates an average value for each pixel.
A comparator 64 as comparison means for comparing the average value for each pixel calculated by the averaging circuit 63 with a preset reference value, a determination means and shading data determination means, and a comparison result of the comparator 64 And a counter circuit 65 that counts the number of times the average value falls below the reference value for each pixel.

In such a configuration, the controller 2
Referring to the schematic flow chart shown in FIG. 15 managed by S3, after the rotation of the reading motor 26 starts (S3
1) The gate signal XS managed by the pulse counter during the period when the gate signal XSFGATE is not active
At the timing (shading position) at which HGATE becomes active (Y in S32), the gate signal SHGATE becomes active (asserted) as shown in FIG.
33), the peripheral surface of the reading roller 12 is
The reading is performed sequentially line by line. The reading area in this case is the target area 50, and a reading unit and a reading step are realized by this processing. The read data in this case is sequentially input to the averaging circuit 63, and an average value is calculated for each pixel of the read data of the L lines, that is, an average value calculation process for obtaining an L line average value (S34). This step S3
The processing of 4 implements an average value calculating means and an average value calculating step. The average value in this case is calculated as a simple average value, but may be a multiple addition average value or the like.

L lines (center angle θ = predetermined width w1)
When the reading process of (C) is completed, the gate signal SHGATE becomes non-active (negated) (S35) and the CCD 4
2, the reading operation of the reading roller 12 in the target area 50 is completed.

The average value for each pixel calculated by the averaging circuit 63 is input to the comparator 64. The comparator 64 determines whether or not the average value can be adopted as shading data by comparing the magnitude relationship between the L line average value and a reference value preset as comparison data for each pixel. Is performed as a stain degree determination process and a shading data determination process for the target area 50 (described later with reference to the following specific example).
The shading data for each pixel is determined, and the determined shading data is output to the shading arithmetic circuit 62 and stored in a memory (not shown) in the shading arithmetic circuit 62.

The shading data for each pixel stored in the memory is used for white shading correction at the time of reading the actual original image (S44). That is, the image data is directly input to the shading arithmetic circuit 62 sequentially for each line when reading the original image.
The image data for each pixel is subjected to white shading correction using the shading data for each pixel obtained from the memory, and is output to a subsequent processing circuit. When the reading operation for the original is completed, the rotation of the reading motor 26 also stops (S
45) Stand by for the next document reading operation.

The above processing is specifically described as follows.

First, the average value of the data of L lines in the averaging circuit 63 and step S34 is obtained by the calculation of the above-mentioned equation (1). That is, Dsg (n) = INT [ΣD (n) / L] (1) Dsg (n): calculation data of the n-th pixel in the target area 50 =
L-line average value D (n): read data of n-th pixel ΣD (n): sum of D (n) from first line to L-th line L: number of lines in target area 50 INT []: decimal point Rounding

The detection of the degree of dirt for each pixel in the target area 50 from each average value and the generation of the shading data Dp (n) are performed by the calculations of equations (6) to (8). When Dsg (n) ≧ Dth (n) Cng (n) = Cng (n) (6) When Dsg (n) <Dth (n) Cng (n) = Cng (n) +1... (7) Cng (n) <NDp (n) = Dsg (n)... (8) Dth (n): n pixels Reference value Cng (n): stain counter for n-th pixel Dp (n): shading data for n-th pixel N: reference value allowable as the degree of stain

That is, after reading the target area 50 of the reading roller 12 and calculating the average value Dsg (n) for each pixel, the comparator 64 calculates the average value Ls line Dsg (n) for each pixel in each pixel. It is compared with a reference value Dth (n) for each stain determination (S36). By the processing in step S36, a comparison unit and a comparison step are realized. Further, the processing in step S8 realizes a determining means and a determining step for determining whether or not the degree of dirt for each pixel in the target area 50 is acceptable, and Dsg (n) ≧ Dth (n) In the case of (S
Y at 36) means that the pixel position in the target area 50 in the reading roller 12 is whitish and free of dirt in comparison with the reference value and is acceptable for shading data acquisition, and Cng (n) = Cng By setting (n) (S37), the dirt counter Cng (n) of the n-th pixel is not updated. On the other hand, if Dsg (n) <Dth (n) (N in S36), the pixel position in the target area 50 in the reading roller 12 is partially contaminated in comparison with the reference value, and shading data acquisition is not performed. Not suitable = meaning that the result is unacceptable, and by setting Cng (n) = Cng (n) +1 (S38), the dirt counter Cng (n) for the n-th pixel is incremented and updated.

If the count value of the dirt counter Cng (n) does not exceed the preset reference value N (S
39) Y means that the pixel position in the target area 50 in the reading roller 12 is whitish and free of dirt, or is temporary such that even if there is dirt, the target area is temporarily recovered. L based on 50 read data
The line average value Dsg (n) is directly determined as shading data (S40). The processing in step S40 is realized as shading data determination means and a shading data determination step.

On the other hand, if the count value of the dirt counter Cng (n) exceeds the preset reference value N (S3
9) N), which means that the pixel position in the target area 50 is partially dirty and is not suitable for obtaining shading data = impossible and unacceptable. A reference value Dth (n) that is preferable to the average value Dsg (n) is determined as shading data (S41). The processing in step S41 realizes shading data determination means and a shading data determination step.

The calculation of the white shading correction is performed by the above equation (5) (when the image data is handled by 8 bits). That is, Dsh = (D (n) / Dp (n)) × 255 (5)

In the present embodiment, the target area 5
If at least one of the L line average values Dsg (n) of a certain pixel of 0 becomes lower than the reference value Dth (n) and the number of times reaches N or more, it is determined that it is not acceptable. In this case (N in S39), as described above, the reference value Dth (n) is determined as the shading data of the pixel (S41), and at the next acquisition of the shading data, the position of the target area 50 is read to be moved. The pulse counter value for the motor 26 is changed (S42). More specifically, as described above with reference to FIG.
Is set so that the position of the next target area moves by an angle of (θ + α). In this case, the angle α is smaller than the angle θ and is a variable angle, that is, (θ +
α) is unequal, and 1
It is preferable to set the value so that it does not return to the original position even after the rotation. In any case, the motor pulse corresponding to the angle (θ + α) is calculated by the CPU in the controller 23. By monitoring the pulse counter value updated in the process of step 32 at the time of next document reading, the process of moving the target position on the reading roller 12 is realized as a target region position moving means and a target region position moving step. You.

In this embodiment, the average value Dsg (n) of the L line of a certain pixel in the target region 50 becomes lower than the reference value Dth (n), and the number of times that the number reaches N or more. Then, if it is determined that it is not acceptable (S39
N), by moving the position of the target area at the next time, the position of the target area 50 due to instantaneous dirt or the like that can be immediately recovered can be avoided.
When there is at least one pixel in which the L line average value Dsg (n) of a certain pixel in the target area 50 is lower than the reference value Dth (n), the pulse counter value for the reading motor 26 is immediately changed. The position of the target area 50 may be changed to be changed (steps S37 to S39 are omitted). According to this, it is possible to quickly cope with a case where a certain pixel of the target area 50 is partially stained.

Therefore, according to the present embodiment, only the target area 50 having a predetermined width on the peripheral surface of the reading roller 12 is read in order to generate shading data. By comparing the line average value Dsg (n) with a preset reference value Dth (n), it is determined whether the degree of partial contamination of each pixel of the target area 50 is acceptable or not. If the L line average value Dsg (n) of the pixel in the region 50 is higher than the reference value Dth (n), it can be determined that the pixel portion of the target region 50 is whitish and not particularly stained. In such a case, the average value Dsg (n) of the L line of the pixel in the target area 50 is used as the shading data.
The shading data becomes appropriate, so that the density uniformity of the shading data can be maintained and a high-quality document image can be read. On the other hand, the target area 5
0, the L line average value Dsg (n) of the pixel is the reference value D.
If it is lower than th (n), it can be determined that the pixel portion of the target area 50 is partially contaminated and is not suitable for shading data acquisition. Reference value Dth
By setting (n) as shading data, appropriate emergency treatment using more preferable data can be performed, and shading data can be determined without the need for processing such as reacquisition of data, and the processing can be shifted to the subsequent processing. The target area 50
Since only reading is required, processing time and processing data can be reduced.

If the target area 50 is determined to be dirty and is not suitable for obtaining shading data, the position of the target area 50 is moved at the next data acquisition. The position of the target area 50 having a predetermined width can be changed to a place with as little dirt as possible, the uniformity of density of shading data can be maintained for a long time, and a high-quality document image can be read.

Further, although a perfect circular roller may be used as the reading roller, it is particularly preferable that the reading roller 12 having a suitable reading surface 13 and the reading roller 12 having a plurality of suitable reading surfaces 13 are preferable. Is the same as

Also, in the case of the present embodiment, even if one L line average value Dsg (n) of a certain pixel in the target region 50 is lower than the reference value Dth (n) by N times or more. Then, when it is determined that it is not permissible (N in S39), the number is counted by the SHNG counter in the controller 23 each time (S43). This SHN
The G counter is used to detect contamination over the entire circumference of the reading roller 12 by cumulatively monitoring the number of negative determination results in step S39. This S
The control by the controller 23 based on the count value of the HNG counter is the same as the case described with reference to FIG. 11, and when it is finally determined that the reading roller 12 is dirty over the entire circumference, the operation unit of the scanner 1 is operated. LC at 38
A warning is displayed on the D display unit to prompt replacement or cleaning of the reading roller 12 (S24).

A third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as in the case of the second embodiment, as shown in FIG.
Basically, only the target area 50 for 1 = L lines is read. Then, based on the read data in the target area 50, the number of pixels that become read data smaller than the preset level value for each main scanning line is counted as comparison data, and the counted number of pixels is set in advance. The degree of dirt in the target area 50, in particular, the degree of local dirt in the main scanning direction is determined by comparing with the reference value, and if it is determined that there is no or little dirt, ,
The calculated average value is directly handled as shading data.

FIG. 16 is a schematic block diagram showing a circuit configuration for performing white shading correction included in the main body image processing circuit of this embodiment. This circuit includes a shading data creation circuit 71 and a shading operation circuit 72 as white shading correction means. The shading data creation circuit 71 includes a comparator 73
, A counter circuit 74, a comparator 75, a memory 76, and an averaging circuit 77. The comparator 73 sequentially receives image data of L lines of the target area 50 and compares, for each main scanning line, whether the read data of each pixel is equal to or larger than a preset level value Dth. The counter circuit 74 functions as a counting unit that counts the number of pixels whose read data is smaller than a preset level value Dth as a comparison result of the comparator 73 for each main scanning line.
The comparator 75 compares and determines whether or not the number of pixels smaller than the level value Dth counted by the counter circuit 74 has reached a preset reference value N, and functions as comparison means and determination means. The memory 7 has a comparator 7
According to the comparison result of No. 5, various scan lines and data for each pixel to be used for shading data creation are stored. The averaging circuit 77 performs a process of obtaining an average value serving as shading data for each pixel using the data stored in the memory 76.

In such a configuration, the controller 2
With reference to the schematic flowchart shown in FIG. 17 managed by the third motor 3, after the rotation of the reading motor 26 starts (S 5).
1) The gate signal XS managed by the pulse counter during the period when the gate signal XSFGATE is not active
At the timing (shading position) at which HGATE becomes active (Y in S52), the gate signal SHGATE becomes active (asserted) as shown in FIG. 13 (S53), and the CCD 42 moves the peripheral surface of the reading roller 12 by the CCD 42. The reading is performed sequentially line by line. The reading area in this case is the target area 50, and a reading unit and a reading step are realized by this processing. The read data in this case is sequentially input to the comparator 73 for each main scanning line, and the read data of each pixel is compared with a preset level value Dth (S54). For example, a description will be given with reference to specific examples. The detection of the degree of dirt for each main scanning line in the target area 50 from the read data and the generation of the shading data Dp (n) are performed by the calculations of equations (9) to (13).

When Dln (n) ≧ Dth Cng (l) = Cng (l) (9) When Dln (n) <Dth Cng (l) = Cng (l) +1... (10) Cng (l) <N Dlp '(n) = Dln (n)... (11) Cng (n) ≧ N Dlp ′ ( n) = Dth (12) Dp (n) = INT [ΣDlp '(n) / L] (13) Dln (n): n pixels on the 1st line Eye read data Dth: Reference level value Cng (l): Dirt counter for l-th line Dlp '(n): Data for creating shading data for n-th pixel on l-line Dp (n): n-th pixel Shading data N: Reference value acceptable as the degree of dirt

That is, the target area 50 of the reading roller 12 is read, and the read data is read by the comparator 73 for each main scanning line.
, And compares the read data Dln (n) of each pixel with a preset level value Dth (S54). If the read data Dln (n) is equal to or greater than the level value Dth (S5
4), Cng (l) = Cng (l) (S5
5) The dirt counter Cng (l) for the 1st line is not counted up. On the other hand, when the read data Dln (n) is smaller than the level value Dth (N in S54), Cng (l) =
By setting Cng (l) +1 (S56), the dirt counter Cng (l) for the first line is counted up. That is, it is counted as the number of pixels smaller than the level value Dth. The process of step S56 is realized as a counting unit and a counting process.

If the count value of the dirt counter Cng (l) does not exceed the preset reference value N (S
57, Y), meaning that the position of the first main scanning line in the target area 50 in the reading roller 12 is whitish and free of dirt, and the read data Dln (n) of the main scanning line in the target area 50 is ) Is stored in the memory 76 as it is, and the shading data creation data Dlp '(n)
(S58). On the other hand, the dirt counter Cng
If the count value of (l) exceeds the preset reference value N (N in S57), the reading roller 12 partially covers the l-th main scanning line in the target area 50 in the target area 50. This means that there is dirt, and a preset level value Dth is stored in the memory 76 and adopted as shading data creation data Dlp '(n) for the main scanning line (S59). The processing in step S57 is realized as a comparing means and a comparing step, and a determining means and a determining step.

Such a process is repeated for L lines, which is the number of lines in the target area 50 (S64). When reading processing for L lines (center angle θ = predetermined width w1) is completed,
The gate signal SHGATE becomes non-active (negated) (S65), and the operation of the CCD 42 for reading the target area 50 of the reading roller 12 ends.

Thereafter, using the shading data generation data Dlp '(n) for L lines stored in the memory 76, the averaging circuit 77 performs processing for obtaining an average value for each pixel by the equation (13) (S66). ), The calculated average value is determined as shading data for each pixel, and the determined shading data is determined by the shading operation circuit 72.
And stored in a memory (not shown) in the shading operation circuit 72. The shading data for each pixel stored in the memory is used for white shading correction at the time of reading the actual original image (S67). That is,
In reading the original image, the shading operation circuit 72 directly inputs the image data sequentially for each line, and uses the shading data for each pixel obtained from the memory to convert the image data for each pixel to white shading. The signal is corrected and output to the processing circuit at the subsequent stage.

The calculation of the white shading correction is performed by the above equation (5) (when the image data is handled by 8 bits). That is, Dsh = (D (n) / Dp (n)) × 255 (5) When the reading operation on the document is completed, the reading motor 26
Also stops (S68), and waits for the next document reading operation.

Regarding the processing for obtaining the average value, only the read data of the main scanning lines in which the count value of the dirt counter Cng (l) has not reached the reference value N are sequentially stored in the memory 76, and each pixel is read by the number of lines. An average value may be calculated for each and used as shading data.

In the present embodiment, the target area 5
If the count value of the dirt counter Cng (l) for the main scanning line of 0 exceeds the reference value N (N in S57), the NG line counter for counting the number of lines is incremented by 1 (S60), and this NG When the count value of the line counter reaches a preset reference value K (S
61), the pulse counter value for the reading motor 26 is changed so as to move the position of the target area 50 at the time of acquiring the next shading data (S62). More specifically, as described above with reference to FIG.
Is set so that the position of the next target area moves by an angle of (θ + α). In this case, the angle α is smaller than the angle θ and is a variable angle, that is, (θ +
α) is not uniform, and 1
It is preferable to set the value so that it does not return to the original position even after the rotation. In any case, the motor pulse corresponding to the angle (θ + α) is calculated by the CPU in the controller 23. By monitoring the pulse counter value updated in the process of step 52 at the time of next document reading, the process of moving the target position on the reading roller 12 is realized as the target region position moving means and the target region position moving step. You.

In this embodiment, when the number of lines whose count value of the dirt counter Cng (l) in the target area 50 exceeds the reference value N reaches K, it is determined that the number of lines is not acceptable. (N in S61) By moving the position of the target area next time, the position of the target area 50 due to instantaneous dirt or the like that can be recovered immediately can be avoided. Counter Cng
If there is at least one main scanning line in which the count value of (l) exceeds the reference value N, the position of the target area 50 may be moved by immediately changing the pulse counter value for the reading motor 26. (Omission of steps S60 to S61). According to this, it is possible to quickly cope with a case where a certain pixel of the target area 50 is partially stained.

Therefore, according to the present embodiment, only the target area 50 having a predetermined width on the peripheral surface of the reading roller 12 is read in order to generate shading data, but is set in advance for each main scanning line in the target area 50. The number of pixels serving as read data smaller than the set level value Dth is counted as comparison data, and the number of pixels counted for each main scanning line is compared with a preset reference value N to obtain the target area 5.
It is determined whether the degree of contamination of each main scanning line of 0 is acceptable or not, and the number of pixels of the target area 50 that becomes read data smaller than the level value Dth of the main scanning line is larger than the reference value N. Otherwise, the main scanning line portion of the target area 50 can be determined to be whitish and not particularly contaminated. Therefore, in such an allowable case, the calculation is performed using the read data of the main scanning line of the target area. Since the obtained value is used as the shading data, the shading data becomes appropriate. Therefore, the density uniformity of the shading data can be maintained and a high-quality original image can be read. Also, the target area 5
Since it is sufficient to read only 0, processing time and processing data can be reduced.

If the target area 50 is determined to be dirty and is not suitable for obtaining shading data, the position of the target area 50 is moved at the next data acquisition. The position of the target area 50 having a predetermined width can be changed to a place with as little dirt as possible, the uniformity of density of shading data can be maintained for a long time, and a high-quality document image can be read.

Further, although a perfect circular roller may be used as the reading roller, a reading roller 12 having a preferable reading surface 13 and a reading roller 12 having a plurality of suitable reading surfaces 13 are particularly preferable in the case described above. Is the same as

Also, in the case of the present embodiment, if it is determined that the main scanning lines of the target area 50 are stained for K lines or more (Y in S61), the number of times is determined by the controller 23. Is counted each time in the SHNG counter (S63). This SHNG counter is used to detect dirt all over the circumference of the reading roller 12 by monitoring the total number of times of the negative determination result in step S61. The control by the controller 23 based on the count value of the SHNG counter is shown in FIG.
And finally the reading roller 12
If it is determined that is dirty over the entire circumference, a warning display for urging replacement or cleaning of the reading roller 12 is displayed on the LCD display unit of the operation unit 38 of the scanner 1 (S24).

A fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, FIG.
As shown in (1), an area including a target area 50 of a predetermined width = L lines and exceeding the target area 50 = S lines is basically read. Then, based on the read data in this area, the number of pixels having read data smaller than a preset level value for each main scanning line is counted as comparison data, and the counted number of pixels is set in advance. By comparing with the reference value, the degree of local contamination of the main scanning line is determined, and the number of main scanning lines (permissible number of main scanning lines) determined to be free or small is sequentially determined. Counting, reading data of each pixel of the main scanning line is stored in the memory, and this process is repeated until the allowable number of main scanning lines reaches the target L line. When the number of lines is reached, the shading data for each pixel is calculated using the read data for these L lines.

Therefore, referring to FIG. 19 which is schematically shown, if the target area 50 is not originally stained,
If the read data in 0 reaches L lines only, but a part of the target area 50 is partially stained, particularly in the main scanning direction, the allowable number of main scan lines is reduced to the target area. Although it is not possible to secure it only in the area 50, by using the read data of the area exceeding the target area 50, it is possible to secure the target L lines as the allowable number of main scanning lines.

As the circuit configuration for performing white shading correction in the present embodiment, the configuration shown in FIG. 16 can be used.

In such a configuration, the controller 2
Referring to the schematic flowchart shown in FIG. 20, which is managed by S3, after the rotation of the reading motor 26 starts (S7).
1) The gate signal XS managed by the pulse counter during the period when the gate signal XSFGATE is not active
When the timing (shading position) at which HGATE becomes active (Y in S72), the gate signal SHGATE becomes active (asserted) as shown in FIG. 18 (S73), and the CCD 42 moves the peripheral surface of the reading roller 12 by the CCD 42. The reading is performed sequentially line by line. The reading area in this case is an area for S lines (S74, S75), and the reading means and the reading step are realized by this processing.

The read data in this case is sequentially input to the comparator 73 for each main scanning line, and the read data of each pixel is compared with a preset level value Dth (S7).
6). Read data Dln of the n-th pixel on the l-th line
If (n) is equal to or greater than the level value Dth (Y in S76), C
By setting ng (l) = Cng (l) (S77), the dirt counter Cng (l) for the first line is not counted up. On the other hand, if the read data Dln (n) is smaller than the level value Dth (N in S76), Cng (l) = Cng (l) +1
(S78), the dirt counter Cng (l) for the l-th line is counted up. That is, it is counted as the number of pixels smaller than the level value Dth. This step S7
8 is realized as a counting means and a counting step.

If the count value of the dirt counter Cng (l) does not exceed the preset reference value N (S
79), which means that the position of the first main scanning line on the reading roller 12 is whitish and free of dirt, and each read data Dln (n) of the main scanning line is stored in the memory 76 as it is to perform shading. It is adopted as data creation data Dlp '(n) (S80), and a counter relating to the number of data acquisition lines is incremented (S8).
1). On the other hand, when the count value of the dirt counter Cng (l) exceeds the preset reference value N (N in S79), it is determined that there is partial dirt on the l-th main scanning line. Means that the processing of steps S80 and S81 is jumped.

In this manner, the storing process for the main scanning lines in which the count value of the dirt counter Cng (l) does not exceed the reference value N is repeated until all the lines have reached L lines (S8).
2), averaging circuit 7 using shading data generation data Dlp '(n) for L lines stored in memory 76;
In step 7, a process for calculating an average value for each pixel is performed by equation (13) (S83), the calculated average value is determined as shading data for each pixel, and the determined shading data is output to the shading operation circuit 72. Then, it is stored in a memory (not shown) in the shading operation circuit 72. The shading data for each pixel stored in the memory is used for white shading correction at the time of reading an actual document image (S84). That is, in reading the original image, the shading operation circuit 72 directly inputs the image data sequentially for each line, and converts the image data for each pixel into image data using the shading data for each pixel obtained from the memory. The white shading correction is performed and output to the subsequent processing circuit.

When the reading operation for the original is completed, the rotation of the reading motor 26 is also stopped (S85), and the apparatus stands by for the next original reading operation.

Therefore, according to the present embodiment, the target area 50 corresponding to a predetermined width = L lines on the peripheral surface of the reading roller 12 is read in order to generate shading data. By reading the data, the S lines are read as a whole, and the number of pixels that become read data smaller than the preset level value Dth for each main scanning line is counted as comparison data, and counted for each main scanning line. By comparing the number of pixels with a preset reference value N, it is determined whether or not the degree of contamination of the main scanning line is allowable, and the level value Dth for the main scanning line is determined.
If the number of pixels that result in smaller read data is not larger than the reference value N, it can be determined that the main scanning line portion is whitish and not particularly dirty. By repeating the determination / judgment process until the number of lines reaches L, the desired L scanning lines can be collected and used for shading data generation, and appropriate shading data can be obtained. , And high-quality document images can be read.

In particular, in the case of the present embodiment, as shown in FIG. 21, a plurality of, for example, three suitable reading surfaces 13a,
Reading roller 1 having 13b, 13c on the peripheral surface at equal intervals
2, when reading the reading roller 12 for shading data creation, a setting is made so as to read an angle (= 120 °) obtained by dividing the peripheral surface of the reading roller 12 into three equal parts as a reading area for S lines. Is preferred. According to such a setting, the reading area is reduced as much as possible for S lines,
A read data portion (a single suitable read surface alone or a state that straddles two suitable read surfaces) that always belongs to the suitable read surface is included in the read area for the S lines, and the main scan that can be used for generating shading data It is ensured that the line read data for L lines is secured, and the density uniformity of the shading data can be maintained at a higher level. Further, according to the method of the present embodiment, basically, the process of moving the position of the target area 50 is not required.

In each of the embodiments described above, the example of the image reading unit 4 using the contact image sensor has been described. However, the present invention is not limited to such an image reading unit. For example, as shown in FIG. An image reading unit 8 including a mirror 82 for reducing and forming optical information of the reading position P on a CCD 81 as a photoelectric conversion element and reading the image, and a reduction optical system 84 including an imaging lens 83 and the like.
5 can be applied in the same manner (even in the case of the above-described embodiment, the image reading unit 3 for reading a double-sided document).
Is equivalent). Reference numeral 86 denotes a light source that performs slit exposure on the surface of the document D at the reading position P. In the case of the contact type image sensor according to the present embodiment, the CCD 42 itself needs a length that covers the entire width of the original document, but is large, but the overall configuration is small, and the reduction optical system 84 as shown in FIG. 29 is used. In this case, the reduction optical system 84 itself is relatively large and easy to increase in size, but the CCD 81 itself for reading the reduced image only needs to be small.

In each of the above-described embodiments, an example in which the present invention is applied to an image forming apparatus such as a copying machine provided with an electrophotographic printer 2 is described. The method is not limited to the photographic method, and the method is not particularly limited as long as an image can be formed on paper based on image data obtained by the scanner 1.

Further, in each of the above-described embodiments, the example in which the scanner 1 is mounted on the image forming apparatus such as a copying machine has been described. However, the image data of the original read by the scanner 1 is transmitted to a public line or a network. The present invention is also applicable to a facsimile apparatus (not particularly shown) for transmitting and outputting to a destination via a communication network.

[0179]

According to the image reading apparatus of the first aspect of the present invention, a target area having a predetermined width on the peripheral surface of the white roller is read to generate shading data. By comparing with the reference value, it is determined whether or not the degree of dirt of the target area is acceptable. If the degree of dirt is not particularly dirty and allowable, the value calculated using the read data of the target area is used as the shading data. As a result, appropriate shading data can be obtained, so that the density uniformity of the shading data can be maintained and a high-quality original image can be read.

According to the image reading apparatus of the present invention, a target area of a predetermined width on the peripheral surface of the white roller is read in order to create shading data. By calculating the average value of each pixel of the read data and the average value of the entire circumference of the read data of the entire circumference for each pixel, and comparing the average value with the average value of the entire circumference, the degree of contamination of each pixel in the target area is determined. Judge whether the degree is acceptable or not, if the average value of the target area is higher than the entire circumference average value, it can be determined that the target area is whiter than other areas and is not particularly dirty, In such a case, when the average value of the pixels in the target area is used as the shading data, appropriate shading data can be obtained, so that the density uniformity of the shading data can be maintained. It is possible to perform the reading of the quality of the original image.

According to the third aspect of the present invention, in the image reading apparatus according to the second aspect, when the average value of the pixel in the target area is lower than the entire circumference average value, the value of the pixel in the target area is reduced. It can be determined that the pixel portion is more dirty than other regions in the sub-scanning direction and is not suitable for shading data acquisition. Since the value is set as the shading data, appropriate first-aid treatment using more preferable data is performed, and the shading data can be determined without the need for processing such as reacquisition of data, and the processing can be shifted to the subsequent processing.

According to the fourth aspect of the present invention, in the image reading apparatus according to the second or third aspect, the reading of the entire circumference of the white roller is performed by a predetermined number of main scanning lines based on the roller diameter of the white roller. Since it is specified, it is possible to easily control the reading operation for acquiring data for the entire circumference of the white roller.

According to the fifth aspect of the present invention, in the image reading apparatus according to the second or third aspect, reading of the entire circumference of the white roller is defined by a gate signal indicating a rotation period of one rotation of the white roller. With this configuration, it is possible to easily control the reading operation for acquiring data for the entire circumference of the white roller.

According to the image reading apparatus of the present invention, only a target area of a predetermined width on the peripheral surface of the white roller is read for generating shading data, but comparison data based on the read data is set in advance. It is determined whether the degree of contamination of the target area is acceptable by comparing it with the reference value that has been set.If the degree of contamination of the target area is acceptable, the value calculated using the read data of the target area is determined. Since the shading data is used, appropriate shading data can be obtained, so that the density uniformity of the shading data can be maintained and a high-quality original image can be read.

According to the seventh aspect of the present invention, in the image reading apparatus according to the sixth aspect, only a target area of a predetermined width on the peripheral surface of the white roller is read in order to create shading data. By comparing the average value of each pixel of the read data with a preset reference value, it is determined whether or not the degree of contamination of each pixel in the target area is acceptable, and the average value of the pixel in the target area is determined. Is higher than the reference value, it can be determined that the pixel portion of the target area is whitish and not particularly dirty than other areas in the sub-scanning direction. Since the average value of the pixel is used as the shading data, appropriate shading data can be obtained, so that the density uniformity of the shading data can be maintained and high quality It is possible to perform the reading of the manuscript image,
Further, since only reading of the target area is sufficient, the processing time and the processing data can be reduced.

According to an eighth aspect of the present invention, in the image reading apparatus according to the seventh aspect, when the average value of the pixel in the target area is lower than the reference value, the pixel portion of the target area is not used. Is more dirty than the other areas in the sub-scanning direction and can be determined to be unsuitable for obtaining shading data. However, if it is unacceptable in this way, a preset reference value is used as shading data. With this configuration, appropriate first-aid treatment using more preferable data can be achieved, and shading data can be determined without performing a process such as reacquisition of data.

According to the ninth aspect of the present invention, in the image reading apparatus according to the sixth aspect, only a target area of a predetermined width on the peripheral surface of the white roller is read for generating shading data. Counting the number of pixels that become read data smaller than a preset level value for each main scanning line as comparison data, and comparing the number of pixels counted for each main scanning line with a preset reference value. It is determined whether or not the degree of dirt for each main scanning line of the target area is acceptable, and the number of pixels that become read data smaller than the level value of the main scanning line of the target area is larger than the reference value. Otherwise, it can be determined that the main scanning line portion of the target area is whitish and not particularly contaminated. Since the value calculated using the in the read data as the shading data,
Proper shading data can be obtained, so that the density uniformity of the shading data can be maintained, high-quality original images can be read, and only the target area needs to be read. It can be reduced.

According to the tenth aspect, the ninth aspect is provided.
In the image reading device described above, when the number of pixels that are read data smaller than the level value of the main scanning line of the target area is not larger than the reference value, the main scanning line portion of the target area is partially Although it can be determined that the data is dirty and is not suitable for obtaining shading data, in the case where such data cannot be tolerated, a level value set in advance is used as the data of the main scanning line. This is an appropriate first aid procedure to be used, and shading data can be determined without any processing such as reacquisition of data.

According to the image reading apparatus of the present invention, a target area of a predetermined width on the peripheral surface of the white roller is read for generating shading data, and an area beyond the target area is also read. The number of pixels serving as read data smaller than a preset level value for each main scanning line is counted as comparison data, and the number of pixels counted for each main scanning line is compared with a preset reference value. Thus, it is determined whether or not the degree of dirt for each main scanning line of the target area is acceptable, and the number of pixels that become read data smaller than the level value of the main scanning line of the target area is smaller than the reference value. If it is not large, it can be determined that the main scanning line portion of the target area is whitish and not particularly dirty, and thus the allowable number of main scanning lines is equal to the predetermined line number. By repeating the determination / judgment process until reaching, a predetermined number of trouble-free main scan lines can be collected for a predetermined number of lines and used for shading data generation, and the shading data becomes appropriate.Thus, the density uniformity of the shading data can be maintained. A high-quality document image can be read.

According to the twelfth aspect, according to the first aspect,
12. The image reading apparatus according to any one of claims 11 to 11, further comprising: target area position moving means for moving the position of the target area on the peripheral surface of the white roller when the result of the judgment by the judging means is unacceptable. When it is not suitable for shading data acquisition, the position of the target area is moved, so that the position of the target area of a predetermined width for acquiring shading data can be changed to a place with as little dirt as possible, and shading Data density uniformity can be maintained over a long period of time, and high-quality document images can be read. In particular, by sequentially changing the locations, the location with the least amount of dirt is finally set as the target area. It can also be converged.

According to the thirteenth aspect, according to the first aspect,
In the image reading apparatus described in Item 2, the target area position moving means moves the position of the target area from the next time when an unacceptable judgment result is obtained by the judgment means. We can deal with it immediately.

According to the fourteenth aspect of the present invention, the first aspect
In the image reading apparatus described in Item 2, the target area position moving means moves the position of the target area from the next time when a judgment result that is unacceptable is obtained by the judgment means a predetermined number of times. The movement of the position of the target area can be avoided.

According to the fifteenth aspect, the first aspect is provided.
In the image reading apparatus according to any one of 2 to 14,
Since the target area position moving means is configured to move the target area position by an angle that does not return to the original target area position when sequentially moving the position of the target area, without trying an unacceptable place again as the target area, Processing for specifying the target area as a clean spot on the peripheral surface of the white roller can be efficiently performed.

According to the sixteenth aspect of the present invention, the first aspect
In the image reading apparatus according to any one of 2 to 14,
Since the target area position moving means sequentially moves the position of the target area by an unequal angle, the target area is not stained on the peripheral surface of the white roller without trying an unacceptable place again as the target area. A process for specifying a location where no data exists can be efficiently performed.

According to the seventeenth aspect, according to the first aspect,
In the image reading apparatus according to any one of 2 to 16,
An all-around dirt detection means for monitoring the total result of the determination that the determination means cannot be allowed to detect dirt over the entire circumference of the white roller, and a warning when the dirt on the entire circumference of the white roller is detected by the all-around dirt detection means. Warning means for issuing a warning, the determination result of the degree of dirt on the target area is unacceptable even if the movement of the target area is repeated as described above, and if the white roller is completely dirty,
By issuing a warning by the warning means, appropriate measures such as cleaning and replacement of the white roller can be taken.

According to the eighteenth aspect of the present invention, the first aspect is provided.
18. In the image reading apparatus according to any one of Items 17 to 17, even when the simplest and easy-to-clean perfect circle roller is used as the white roller, the uniformity of density of shading data can be maintained, and a high-quality original image can be read. It can be performed.

According to the invention of claim 19, claim 1
18. The image reading apparatus according to any one of claims 17 to 17, wherein the white roller is formed by a curved surface having a center of curvature on a straight line perpendicular to the roller axis on the outer peripheral surface and located inside the locus of the maximum outer peripheral surface of the roller. A roller having a preferred reading surface is used, so that the preferred reading surface does not easily come in contact with the original even if the original is transported repeatedly. Since it is difficult to collect and easy to clean, the preferable reading surface can be maintained in a white state for a long period of time. In generating shading data, there is a possibility that such a preferable reading surface is read as a target area, so that shading is performed. The uniformity of data density is maintained at a higher level, and high-quality original images can be read. The reading surface there are no problems, such as to produce a shadow caused.

According to the twentieth aspect, according to the first aspect,
In the image reading device according to Item 9, since the predetermined width of the target area is set to be smaller than the width of the suitable reading surface, when the target area is completely located within the preferable reading surface, the uniformity of the density of the shading data is reduced. Even higher levels can be maintained.

According to the twenty-first aspect, the first aspect is described.
21. In the image reading device according to 9 or 20, since the white roller has a plurality of the preferable reading surfaces on the peripheral surface, the possibility of reading the preferable reading surface as a target area is increased, and the density uniformity of shading data is further improved. Can be maintained at a high level.

According to the twenty-second aspect, the second aspect is provided.
In the image reading apparatus described in Item 1, since the plurality of suitable reading surfaces are provided at equal intervals on the peripheral surface of the white roller, the possibility of reading the preferable reading surface as a target area increases, and the density of the shading data becomes uniform. In particular, when the position of the target area is moved, the moving amount is made uneven, thereby increasing the possibility of reading a suitable reading surface as the target area. be able to.

According to the twenty-third aspect of the present invention, the second aspect is provided.
In the image reading apparatus described in 1, the plurality of suitable reading surfaces are provided at non-uniform intervals on the peripheral surface of the white roller. Concentration uniformity can be maintained at a higher level, especially when the position of the target area is moved, even when the movement amount is made uniform.
It is possible to increase the possibility of reading a preferred reading surface as a target area.

According to the invention of claim 24, claim 1
In realizing the invention of (1), one suitable reading surface is always included in the reading region while making the reading region as small as possible, and the main scanning line read data that can be used for shading data generation is stored for a predetermined line. As a result, the density uniformity of the shading data can be maintained at a higher level.

According to the twenty-fifth aspect, the first aspect is provided.
24. The image reading apparatus according to any one of the items 24 to 24, which can be suitably applied to an original reading type image reading apparatus in which the photoelectric conversion element itself is large but the overall configuration is small.

According to the invention of claim 26, claim 1
24. The image reading apparatus according to any one of the items 24 to 24, which requires a relatively large reduction optical system and is easy to increase in overall configuration, but is suitable for an original reading type image reading apparatus that requires only a small photoelectric conversion element. It can be suitably applied.

According to the twenty-seventh aspect of the present invention, there is provided the image forming apparatus according to any one of the first to twenty-sixth aspects, wherein the image data of the document corrected by using highly reliable shading data is provided. Therefore, an image forming apparatus capable of forming a high-quality image can be provided.

According to a twenty-eighth aspect of the present invention, there is provided the facsimile apparatus according to any one of the first to twenty-sixth aspects, wherein the image data of the document corrected by using highly reliable shading data is provided. Therefore, a facsimile apparatus capable of transmitting and outputting a high-quality image can be provided.

According to the shading data creating method of the present invention, a target area of a predetermined width on the peripheral surface of the white roller is read for shading data creation.
At the same time, the entire circumference is also read, and the average value of the read data for each pixel in the target area and the average value of the entire circumference of the read data for each pixel are calculated and the average value is compared with the average value of the entire circumference It is determined whether the degree of dirt for each pixel of the target area is acceptable by performing the processing.If the average value of the target area is higher than the average value of the entire circumference, the target area is higher than the other areas. In this case, the average value of the pixel in the target area is used as the shading data in such an allowable case, so that appropriate shading data can be obtained. Data density uniformity can be maintained.

According to the thirtieth aspect, the second aspect is provided.
9. In the shading data creation method according to 9, when the average value of the pixel in the target area is lower than the entire circumference average value, the pixel portion of the target area is more partial than other areas in the sub-scanning direction. Can be determined to be unsuitable for shading data acquisition, but in such an unacceptable case, the entire circumference average value on the peripheral surface of the pixel is determined as shading data.
Appropriate emergency treatment using more preferable data is performed, and shading data can be determined without requiring processing such as reacquisition of data.

According to the shading data generating method of the present invention, only the target area of a predetermined width on the peripheral surface of the white roller is read for shading data generation, but every pixel of the read data in the target area is read. It is determined whether or not the degree of dirt for each pixel of the target area is acceptable by comparing the average value of the target area with a preset reference value,
When the average value of the pixel in the target area is higher than the reference value, the pixel portion of the target area can be determined to be whitish and not particularly dirty than other areas in the sub-scanning direction. In the case where the average value of the pixels in the target area is used as the shading data, appropriate shading data can be obtained, and thus the density uniformity of the shading data can be maintained. Since it is sufficient to read only the target area, the processing time and processing data can be reduced.

According to the invention of claim 32, claim 3
1. In the shading data creation method according to item 1, when the average value of the pixel in the target area is lower than the reference value, the pixel portion of the target area is more partially stained than other areas in the sub-scanning direction. It can be determined that the shading data is not suitable, but if it is not acceptable in this way, a preset reference value is used as the shading data for the time being. This is a measure, and shading data can be determined without requiring processing such as reacquisition of data.

According to the shading data generating method of the present invention, only a target area of a predetermined width on the peripheral surface of the white roller is read for generating shading data. The number of pixels serving as read data smaller than a preset level value is counted as comparison data, and the number of pixels counted for each main scanning line is compared with a preset reference value, thereby obtaining the target area. It is determined whether the degree of dirt for each main scanning line is acceptable or not. If the number of pixels of read data smaller than the level value of the main scanning line in the target area is not larger than the reference value, Since it can be determined that the main scanning line portion of the target area is whitish and not particularly dirty, the main scanning line of the target area can be determined in such an allowable case. Since the value calculated using the read data is used as the shading data, appropriate shading data can be obtained, so that the density uniformity of the shading data can be maintained. Therefore, processing time and processing data can be reduced.

According to the thirty-fourth aspect, in the third aspect,
2. In the shading data creation method described in 2, the main scanning line portion of the target region is partially set if the number of pixels that become read data smaller than the level value of the main scanning line of the target region is not larger than the reference value. It is determined that the data is dirty and is not suitable for obtaining shading data. However, in the case where such data cannot be tolerated, a level value set in advance as the data of the main scanning line is used. This is an appropriate emergency treatment using the data, and the shading data can be determined without requiring processing such as reacquisition of the data.

According to the invention of claim 35, claim 2
35. The shading data creating method according to any one of claims 9 to 34, further comprising a target area position moving step of moving the position of the target area on the peripheral surface of the white roller when the result of the determination step is not acceptable. Is dirty and not suitable for shading data acquisition,
Since the position of the target area is moved, the position of the target area having a predetermined width for acquiring shading data can be changed to a place with as little dirt as possible, and the density uniformity of the shading data can be maintained for a long time. It is possible to read a high-quality document image, and by sequentially changing the locations, it is possible to converge so that the location with the least amount of dirt finally becomes the target area.

According to the shading data creation method of the present invention, a target area of a predetermined width on the peripheral surface of the white roller is read for shading data creation.
At the same time, the area beyond the target area is also read, and the number of pixels that become read data smaller than a preset level value for each main scanning line is counted as comparison data, and the pixels counted for each main scanning line are counted. By comparing the number with a preset reference value, it is determined whether or not the degree of dirt for each main scanning line in the target area is acceptable, and the level is determined based on the level value of the main scanning line in the target area. If the number of pixels that result in small read data is not larger than the reference value, the main scanning line portion of the target area can be determined to be whitish and not particularly stained. Decide until the number is reached
By repeating the determination processing, a predetermined number of main scanning lines that do not interfere with each other can be collected and used for shading data generation, and appropriate shading data can be obtained. Therefore, density uniformity of shading data can be maintained.

According to the thirty-seventh aspect, the second aspect is provided.
39. The shading data creation method according to any one of 9 to 36, wherein the roller has a center of curvature on a straight line perpendicular to the roller axis on its outer peripheral surface, and has a curved surface located inside the maximum outer peripheral surface locus of the roller. Since the roller having the formed preferable reading surface is used, the preferable reading surface is hard to be stained because it is difficult to come in contact with the original even when the original is repeatedly conveyed. Since it is difficult to collect on the top and easy to clean, the suitable reading surface can be maintained in a white state for a long time,
In generating shading data, there is a possibility that such a suitable reading surface is read as a target area, so that the density uniformity of shading data can be maintained at a higher level.

[Brief description of the drawings]

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

FIG. 2 is an enlarged longitudinal front view showing a document conveying path near a second reading roller.

FIG. 3 is an enlarged vertical sectional front view of a second reading roller.

FIG. 4 is a schematic block diagram showing an electrical connection of a control system of the copying machine.

FIG. 5 is a schematic block diagram illustrating a control system for an electrical hardware configuration inside a second image reading unit.

FIG. 6 is a timing chart showing basic timing of a gate signal.

FIG. 7 is a longitudinal sectional front view showing a target area having a predetermined width.

FIG. 8 is a schematic block diagram illustrating a circuit configuration for performing shading correction.

FIG. 9 is an explanatory diagram showing a target area having a predetermined width.

FIG. 10 is a flowchart illustrating a control example of a reading operation for a reading roller.

FIG. 11 is a flowchart illustrating an example of control relating to an abnormality in overall surface contamination.

FIG. 12 is a front view showing a modification of the reading roller.

FIG. 13 is an explanatory diagram illustrating a target area having a predetermined width according to the second embodiment of this invention.

FIG. 14 is a schematic block diagram illustrating a circuit configuration for performing shading correction.

FIG. 15 is a flowchart illustrating a control example of a reading operation for a reading roller.

FIG. 16 is a schematic block diagram illustrating a circuit configuration for performing shading correction according to a third embodiment of the present invention.

FIG. 17 is a flowchart illustrating a control example of a reading operation for a reading roller.

FIG. 18 is an explanatory diagram showing a reading area according to the fourth embodiment of the present invention.

FIG. 19 is an explanatory diagram schematically showing an example of the reading process.

FIG. 20 is a flowchart illustrating a control example of a reading operation for a reading roller.

FIG. 21 is a front view illustrating a relationship between a reading roller and a reading area.

FIG. 22 is a schematic front view showing a modification of the image reading unit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 image reading device 4 image reading section 7 document conveying path 12 white roller 13, 13a to 13c suitable reading surface 20 paper 26 drive source 42 photoelectric conversion element 50 target area 52 white shading correction means 53, 54 average value calculation means 55 comparison means Determination means, shading data determination means 62 white shading correction means 63 average value calculation means 64 comparison means 65 counting means 72 white shading correction means 74 counting means 75 comparison means 81 photoelectric conversion element 84 reduction optical system 85 image reading section

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Hattori 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hiroshi Kubo 1-3-6 Nakamagome, Ota-ku, Tokyo Share F term in Ricoh Company (reference) 5B047 AA01 BA01 BB02 CB21 CB25 DA04 DC20 5C062 AA05 AB17 AB29 AB42 AC21 AC58 AC61 BA00 5C072 AA01 BA08 BA13 FB12 NA01 RA16 UA02 UA11 UA20 XA01

Claims (37)

[Claims] An image reading section having a document transport path on which a document is transported, a photoelectric conversion element for setting a reading position for the document transported on the document transport path, and reading an image of the document; A white roller that is disposed opposite to the reading position of the image reading unit with the document conveying path interposed therebetween and is driven to rotate in the document conveying direction by a driving source; and a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element. Reading means for reading the target area; comparing means for comparing comparison data based on the read data in the target area read by the reading means with a reference value; Determining means for determining whether or not the degree is acceptable; and when the determination result by the determining means is acceptable, calculation is performed using read data in the target area. Shading data determining means for determining a value as shading data, and white shading correcting means for performing white shading correction on image data of a document read by the photoelectric conversion means using the shading data determined by the shading data determining means. Image reading device provided. An image reading section having a document transport path on which the document is transported, a photoelectric conversion element for setting a reading position for the document transported on the document transport path, and reading an image of the document; A white roller that is disposed opposite to the reading position of the image reading unit with the document conveying path interposed therebetween and is driven to rotate in the document conveying direction by a driving source; and a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element. Reading means for reading the entire circumference including the target area; an average value for each pixel of read data in the target area read by the reading means for each pixel; Average value calculating means for calculating the average value for each pixel calculated by the average value calculating means, and comparing means for comparing the average value for each pixel as a reference value with the entire circumference average value for each pixel, ratio Judging means for judging whether or not the degree of dirt for each pixel in the target area is acceptable based on the comparison result; and, if the judgment result by the judging means is an acceptable pixel, the average value of the pixel is represented by shading data. An image reading apparatus comprising: a shading data determining unit that determines the image data; and a white shading correcting unit that performs white shading correction on image data of a document read by the photoelectric conversion unit using the shading data determined by the shading data determining unit. . 3. The shading data determining means according to claim 1,
3. The image reading apparatus according to claim 2, wherein, when the result of the determination by the determination unit is an unacceptable pixel, the entire circumference average value of the pixel is determined as shading data. 4. The reading device according to claim 2, wherein the reading means defines the reading of the entire circumference of the white roller by a predetermined number of main scanning lines based on the roller diameter of the white roller.
The image reading device according to claim 1. 5. The image reading apparatus according to claim 2, wherein the reading unit defines reading of the entire circumference of the white roller by a gate signal indicating a rotation period of one rotation of the white roller. 6. A document transport path on which a document is transported, an image reading unit having a photoelectric conversion element for setting a reading position for the document transported on the document transport path and reading an image of the document, A white roller that is disposed opposite to the reading position of the image reading unit with the document conveying path interposed therebetween and is driven to rotate in the document conveying direction by a driving source; and a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element. Reading means for reading only the target area; comparing means for comparing comparison data based on the read data in the target area read by the reading means with a preset reference value; Judging means for judging whether the degree of dirt in the target area is acceptable; and, if the judgment result by the judging means is acceptable, reading data in the target area. Shading data determining means for determining a value calculated using the shading data as shading data, and white shading correction of the image data of the original read by the photoelectric conversion means using the shading data determined by the shading data determining means. An image reading device comprising: 7. An average value calculating means for calculating an average value of read data in the target area for each pixel as comparison data, wherein the comparing means compares the average value of each pixel with the reference value, The determining means determines whether or not the degree of contamination of each pixel in the target area is allowable based on a comparison result by the comparing means. The image reading device according to claim 6, wherein the average value of the pixels is determined as shading data. 8. The shading data determination means,
8. The image reading apparatus according to claim 7, wherein the reference value set in advance is determined as shading data when the result of the determination by the determination unit is an unacceptable pixel. 9. A counting means for counting, as comparison data, the number of pixels that become read data smaller than a preset level value for each main scanning line in the target area, wherein the comparing means is provided for each main scanning line. Comparing the number of pixels counted in the above with the reference value, the determining means determines whether the degree of dirt for each main scanning line in the target area is acceptable based on the comparison result by the comparing means, 7. The image reading apparatus according to claim 6, wherein the shading data determination unit determines, as the shading data, a value calculated using read data of the main scanning line when the determination result is an acceptable main scanning line. 10. The shading data determination unit according to claim 9, wherein, when the determination result by the determination unit is an unacceptable main scanning line, the level value preset as data of the main scanning line is used. Image reading device. 11. An image reading section having a document transport path on which a document is transported, a photoelectric conversion element having a reading position set for the document transported on the document transport path and reading an image of the document, A white roller that is disposed opposite to the reading position of the image reading unit with the document conveying path interposed therebetween and is driven to rotate in the document conveying direction by a driving source; and a predetermined width on the peripheral surface of the white roller by the photoelectric conversion element. A reading unit for reading an area including the target area and exceeding the target area is compared with the number of pixels of read data read by the reading unit which becomes read data smaller than a preset level value for each main scanning line. A counting means for counting as data, and a comparing means for comparing the number of pixels counted for each main scanning line by the counting means with a preset reference value. Determining whether or not the degree of dirt for each main scanning line is acceptable based on the comparison result by the comparing means, and repeating this determination processing until the allowable number of main scanning lines reaches a predetermined number of lines. And a shading data determining means for determining the value calculated by using the read data of the predetermined number of lines as shading data if the determination result by the determining means is repeated until the predetermined number of lines is reached and the determination result is acceptable. An image reading apparatus comprising: a white shading correction unit configured to perform white shading correction on image data of a document read by the photoelectric conversion unit using the shading data determined by the shading data determination unit. 12. The apparatus according to claim 1, further comprising a target area position moving means for moving the position of the target area on the peripheral surface of the white roller when the result of the judgment by the judgment means is not acceptable. Image reading device. 13. The image reading apparatus according to claim 12, wherein the target area position moving means moves the position of the target area from the next time when an unacceptable judgment result is obtained by the judgment means. 14. The image reading apparatus according to claim 12, wherein the target area position moving means moves the position of the target area from the next time when a determination result that is not acceptable by the determining means is obtained a predetermined number of times. 15. The image reading apparatus according to claim 12, wherein the target area position moving means moves the target area by an angle that does not return to the original target area position when the target area is sequentially moved. apparatus. 16. The target area position moving means sequentially moves the position of the target area by unequal angles.
15. The image reading device according to any one of 2 to 14. 17. A full-circumference dirt detecting means for cumulatively monitoring the judgment result by the judging means that it is unacceptable to detect dirt over the entire circumference of the white roller; 17. The image reading apparatus according to claim 12, further comprising: a warning unit that issues a warning when the image is detected. 18. The image reading apparatus according to claim 1, wherein said white roller is a perfect circular roller. 19. The white roller has, on its outer peripheral surface, a preferable reading surface formed of a curved surface having a center of curvature on a straight line orthogonal to the roller axis and located inside the locus of the maximum outer peripheral surface of the roller. The image reading device according to claim 1, wherein the image reading device is a roller. 20. The image reading apparatus according to claim 19, wherein a predetermined width of the target area is set to be smaller than a width of the preferred reading surface. 21. The image reading apparatus according to claim 19, wherein the white roller has a plurality of the preferable reading surfaces on a peripheral surface. 22. The image reading apparatus according to claim 21, wherein the plurality of preferable reading surfaces are provided at equal intervals on a peripheral surface of the white roller. 23. A plurality of preferred reading surfaces are provided at uneven intervals on a peripheral surface of the white roller.
2. The image reading device according to 1. 24. The white roller has a center of curvature on a straight line perpendicular to the roller axis on its outer peripheral surface, and has a suitable reading surface formed by a curved surface located inside the locus of the maximum outer peripheral surface of the roller. 12. The image reading apparatus according to claim 11, wherein a plurality of reading sections are provided at equal intervals on the surface, and the reading means reads a range of an angle obtained by equally dividing the entire circumference by at least the number of the preferable reading surfaces. 25. The image reading apparatus according to claim 1, wherein the image reading section is a contact image sensor in which the photoelectric conversion element itself is arranged at the reading position. 26. The image reading apparatus according to claim 1, wherein the image reading section includes a reduction optical system configured to read out the optical information at the reading position by forming a reduced image on the photoelectric conversion element. 27. An image forming apparatus comprising: the image reading device according to claim 1; and forming an image on a recording medium based on image data of a document read by the image reading device. 28. A facsimile apparatus comprising the image reading device according to claim 1, and transmitting and outputting image data of a document read by the image reading device to a destination via a communication network. 29. A peripheral surface of a white roller disposed opposite to the reading position with the photoelectric conversion element of an image reading unit in which a reading position is set for a document conveyed on the document conveying path sandwiching the document conveying path. A reading step of reading the entire circumference including the target area having the upper predetermined width, and an average value of each pixel of read data in the target area read in the target area and a read data of each pixel of the entire circumference. An average value calculating step of calculating an average value of the entire circumference; a comparing step of comparing the average value of each pixel calculated in the average value calculating step with the average value of the entire circumference of each pixel; A judging step of judging whether or not the degree of dirt for each pixel in the target area is acceptable based on the comparison result; and, if the judgment result in this judging step is an acceptable pixel, the average value of the pixel is determined by shading data. Shading data generation method and a shading data determination step of determining a. 30. The shading data generation method according to claim 29, wherein in the shading data determining step, when the result of the determination in the determining step is an unacceptable pixel, the entire circumference average value of the pixel is determined as shading data. 31. A peripheral surface of a white roller which is opposed to the reading position with the photoelectric conversion element of an image reading unit in which a reading position is set for a document conveyed on the document conveying path sandwiching the document conveying path. A reading step of reading only the target area having the upper predetermined width; an average value calculating step of calculating an average value for each pixel of read data in the target area read in the reading step; A comparison step of comparing the calculated average value of each pixel with a preset reference value; and, based on a result of the comparison step, determining whether the degree of contamination of each pixel in the target area is acceptable. A judging step of judging, and a shading data determining step of determining the average value of the pixel as shading data when the judgment result in the judging step is acceptable. Shading data creation method to obtain. 32. The shading data according to claim 31, wherein the shading data determining step determines the preset reference value as shading data of the pixel when the result of the determination in the determining step is an unacceptable pixel. How to make. 33. A peripheral surface of a white roller which is opposed to the reading position with the photoelectric conversion element of an image reading unit in which a reading position is set for a document conveyed on the document conveying path sandwiching the document conveying path. A reading step of reading only the target area having the upper predetermined width, and counting the number of pixels having read data smaller than a preset level value for each main scanning line in the target area read in the reading step. A counting step; a comparing step of comparing the number of pixels counted for each main scanning line by the counting step with a preset reference value; and a main scanning line in the target area based on a comparison result of the comparing step. A judgment step of judging whether or not the degree of dirt is acceptable for each main scanning line. Shading data generating method comprising: a shading data determination step of determining a value calculated had as shading data. 34. The shading data determining step determines a value calculated using the preset level value as shading data when the result of the determination in the main scanning line is unacceptable. Item 36. The shading data creation method according to Item 32. 35. A target area position moving step of moving the position of the target area on the peripheral surface of the white roller when the result of the judgment step is unacceptable.
35. The shading data creation method according to any one of claims 34. 36. A peripheral surface of a white roller which is opposed to the reading position with the photoelectric conversion element of an image reading unit in which a reading position is set for a document conveyed on the document conveying path sandwiching the document conveying path. A reading step of reading an area including the target area having the upper predetermined width and exceeding the target area; and reading data smaller than a level value preset for each main scanning line for the read data read in the reading step. A counting step of counting the number of pixels, a comparing step of comparing the number of pixels counted for each main scanning line by the counting step with a preset reference value, and a main scanning line based on a comparison result of the comparing step. A determining step of determining whether or not the degree of dirt is acceptable for each case, and repeating this determination processing until the allowable number of main scanning lines reaches a predetermined number of lines And a shading data determining step of determining a value calculated by using the read data of the predetermined number of lines as shading data if the determination process is repeated until the predetermined number of lines is reached and the determination result is acceptable. And a shading data creation method comprising: 37. The white roller to be read in the reading step has a center of curvature on a straight line orthogonal to the roller axis on the outer peripheral surface thereof and is a curved surface located inside the locus of the maximum outer peripheral surface of the roller. 37. The shading data creation method according to claim 29, wherein a roller having a suitable reading surface is used.