JP2006217481A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform accurate shading correction while solving the problem that it is difficult to install a white reference member about shading correction at a fixed read means side in the case of reading both sides. <P>SOLUTION: This image reader has a first read means having a movable read opening for reading the first side of an original, a fixed second read means for reading the second side of the original, a second white reference member arranged at a reading position of the second read means to convey an original and also to be read by the second read means in a state with no original existing, and a second shading correction means for generating whiteness correction data from a difference in pixels with each other at the same position between initial second whiteness reference member read data obtained by reading the second white reference member and white reference original data obtained by reading a white reference original of a material having whiteness equivalent to that of a first white reference member by the second read means and using the whiteness correction data to generate second shading correction data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus having a function of reading both-side images while generating a document and generating image data, and more particularly to an image reading apparatus in consideration of shading correction.

2. Description of the Related Art Conventionally, an image reading apparatus capable of reading both sides of a document has been widely used.
Such a double-sided reading type image reading apparatus has one reading unit and a document reversing and conveying mechanism, and after reading the first surface of the document by conveying the document to the image reading position, There are some which read the image on the second surface by the reading means by reversing the front and back and transporting the document again to the image reading position.

  Further, such a double-sided reading type image reading apparatus has a first reading unit for reading the first side of the document and a second reading unit for reading the second side, and transports the document once. There is a so-called double-sided simultaneous reading type image reading apparatus that can read images on both sides of a document simultaneously or in parallel.

  Here, although the double-sided simultaneous reading type image reading apparatus requires two reading units, since both sides can be read almost simultaneously with one original conveyance, high-speed reading and document conveyance are possible. Since the mechanism is simple, it has many advantages such as low failure and low cost.

  By the way, in image reading, shading correction using the reading result of the white reference member is generally performed in order to correct the influence on the image data by the light source that illuminates the document or the reading optical system.

  By the way, in the above-described double-sided reading type image reading apparatus, as the first reading means, the first reading means having a movable reading opening (such as a movable mirror portion) and the fixed second reading means are used. There are many cases.

  Here, since the first reading means has a movable reading opening, the positional restriction for providing the white reference member is loose, and there is no problem in installing the white reference member. However, since the reading opening of the second reading unit is fixed, there is a problem that it is difficult to provide the white reference member.

Regarding the shading correction by such a fixed second reading means, a solving means is described in Patent Document 1 below.
Japanese Patent Laying-Open No. 2004-207790 (first page, FIG. 1)

  In the above-mentioned Patent Document 1, regarding the shading correction by the fixed second reading means, an attempt is made to solve the problem that it is difficult to install the white reference member by reading the background portion of the document.

  However, although shading correction using the background portion of the document can contribute to simplifying the configuration of the apparatus, there remains a problem that it is not suitable for accurate shading correction.

  In addition, it is possible to make the conveyance roller of the second reading unit white and also use it as a white reference member, but in that case, the difference in whiteness due to the material difference from the white reference member of the first reading unit There are various problems such as the problem of smearing due to the document passing.

  The present invention has been made in order to solve the above-described problems, and uses a fixed-type reading unit for reading one side, and reads images on both sides in parallel while conveying a document. Provided an image reader capable of accurate shading correction while solving the problem of difficult to install the white reference member for shading correction with a fixed reading means when generating image data for both sides The purpose is to do.

The present invention for solving the above problems is as described below.
(1) The invention according to claim 1 is an image reading apparatus having a function of reading images on both sides while conveying a document and generating respective image data on both sides, a document conveying means for conveying the document, A first reading unit having a movable reading opening for reading the first surface of the conveyed document; and a moving range of the reading opening of the first reading unit outside the reading region of the document. A first white reference member that is read by the first reading unit, a fixed second reading unit that reads a second surface of the conveyed document, and a reading position of the second reading unit. Is transported while the document is in close contact with the second reading means, and when the document is not present, the second reading is performed. A second white reference member read by the taking means, a first shading correction means for correcting the shading of the image data generated by the reading by the first reading means by the first shading correction data, and the second reading means Second shading correction means for correcting shading image data generated by reading with second shading correction data, and control means for generating the first shading correction data and the second shading correction data, The control means is a material having initial second white reference member reading data obtained by reading the second white reference member by the second reading means at the initial stage and a whiteness equivalent to that of the first white reference member. As a third white reference member that does not constitute the image reading device Whiteness correction data is generated from the difference between pixels at the same position with the white reference original data obtained by reading the white reference original by the second reading means, and the second white reference member is moved to the first white reference member when the correction data is generated. A second shading correction data is generated from correction second white reference member reading data obtained by reading with two reading means and the whiteness correction data.

  (2) The invention according to claim 2 is an image reading apparatus having a function of reading images on both sides while conveying a document and generating respective image data on both sides, a document conveying means for conveying the document, A first reading unit having a movable reading opening for reading the first surface of the conveyed document; and a moving range of the reading opening of the first reading unit outside the reading region of the document. A first white reference member that is read by the first reading unit, a fixed second reading unit that reads a second surface of the conveyed document, and a reading position of the second reading unit. When the document is being conveyed, the document is driven while being in close contact with the second reading means, and when the document is not present, the second reading is performed. A second white reference member read by the taking means, a first shading correction means for correcting the shading of the image data generated by the reading by the first reading means by the first shading correction data, and the second reading means A second shading correction unit that corrects shading of image data generated by reading with second shading correction data; and a control unit that generates the first shading correction data and the second shading correction data. The second reading means and the second white reference member are both configured to be larger than the maximum reading width of the document, and the control means is configured to make the second reading means outside the reading area of the second white reference member at the initial stage. The initial second white reference member reading obtained by reading From the difference between the out-of-region data and the correction-out second white reference member reading region data obtained by reading the outside of the second white reference member reading region with the second reading means when the correction data is generated Material that has initial white second reference member reading data obtained by generating change data and reading the second white reference member by the second reading means at the initial stage, and whiteness equivalent to the first white reference member The whiteness correction data is obtained from the difference between the pixels at the same position with the white reference original data obtained by reading the white reference original as a third white reference member that does not constitute the image reading device by the second reading means. The second white reference member reading data at the time of correction obtained by reading the second white reference member with the second reading means when the correction data is generated and the white color The image reading apparatus is characterized in that second shading correction data is generated from the degree correction data and the light amount temporal change data.

  (3) The invention described in claim 3 is provided with display means for displaying various states, and the control means is obtained by reading the reading area of the second white reference member by the second reading means at the initial stage. Initial second white reference member reading region out-of-region data, and correction second white reference member reading region out-of-region data obtained by reading out the reading region of the second white reference member by the second reading unit when generating correction data. From the difference between the first white white reference member reading data obtained by reading the second white reference member with the second reading means at the initial time and the second white color at the time of generating correction data. From the difference from the corrected second white reference member reading data obtained by reading the reference member with the second reading means, generating fouling data, the fouling data and the When the difference from the quantity change data over a predetermined level is equal to or greater than a predetermined level, a contamination has occurred in the reading area of the second white reference member, or a service call request is displayed. The image reading apparatus according to claim 2.

  (4) The invention according to claim 4 is characterized in that the control means has an average value of the first white reference original data obtained by reading the third white reference member by the first reading means, and the second reading means. The sensitivity correction between the first reading unit and the second reading unit is executed based on a difference from an average value of the white reference original data obtained by reading the third white reference member. An image reading apparatus according to any one of claims 1 to 3.

According to the present invention, the following effects can be obtained.
(1) According to the first aspect of the present invention, when the images on both sides are read while the document is conveyed to generate the respective image data on both sides, the first reading means having a movable reading opening is used for the first reading of the document. The surface is read, and the second surface of the document is read by the second reading means having a fixed reading opening.

  Here, the first shading correction data is generated by reading the first white reference member which is outside the original reading area and is provided in the movable range of the reading opening of the first reading means, and is generated by the first reading means. The obtained image data is subjected to shading correction.

  Here, the second white reference member arranged at the reading position of the second reading means is read by the second reading means at the initial stage, and initial second white reference member reading data is generated. A white reference document as a third white reference member made of a material having the same whiteness as that of the first white reference member is read by the second reading unit, and white reference document data is generated. Then, whiteness correction data is generated from the difference between pixels at the same position in the initial second white reference member read data and the white reference original data.

  Then, the second shading correction data is generated from the corrected second white reference member reading data and the whiteness correction data, and the image data generated by the second reading means is subjected to shading correction.

  As a result, the second white reference member is arranged at the reading position of the second reading means and also serves as a conveying means such as a roller or a belt, so that the second white reference in the second reading means having a fixed reading opening is provided. The difficulty of installing the member is eliminated.

  Then, whiteness correction data is generated from the difference between the same position pixels of the white reference document data by the third white reference member and the initial second white reference member read data, and the second shading correction is performed using the whiteness correction data. Since the data is generated, the difference in whiteness due to the difference in material between the first white reference member and the second white reference member is corrected, and accurate shading correction can be performed.

  (2) In the invention described in claim 2, when the both sides of the image are read while the original is conveyed to generate the respective image data of the both sides, the first reading means having a movable reading opening is used for the first reading of the original. The surface is read, and the second surface of the document is read by the second reading means having a fixed reading opening.

  Here, the first shading correction data is generated by reading the first white reference member which is outside the original reading area and is provided in the movable range of the reading opening of the first reading means, and is generated by the first reading means. The obtained image data is subjected to shading correction.

  Here, the second white reference member arranged at the reading position of the second reading means is read by the second reading means at the initial stage, and initial second white reference member reading data is generated. The second reading means and the second white reference member are both configured to be larger than the maximum reading width of the original, and the second reading means reads the outside of the reading area of the second white reference member, and the initial second white reference member is read. Data outside the reference member reading area is generated.

  A white reference document as a third white reference member made of a material having the same whiteness as that of the first white reference member is read by the second reading unit, and white reference document data is generated. Also, whiteness correction data is generated from the difference between pixels at the same position in the initial second white reference member reading data and the white reference original data. Further, the light amount temporal change data is generated based on the difference between the initial second white reference member reading area data and the corrected second white reference member reading area data.

  Then, second shading correction data is generated from the corrected second white reference member reading data, whiteness correction data, and light amount change data, and the image data generated by the second reading means is subjected to shading correction. The

  As a result, the second white reference member is arranged at the reading position of the second reading means and also serves as a conveying means such as a roller or a belt, so that the second white reference in the second reading means having a fixed reading opening is provided. The difficulty of installing the member is eliminated.

  Then, whiteness correction data is generated from the difference between the same position pixels of the white reference document data by the third white reference member and the initial second white reference member read data, and the second shading correction is performed using the whiteness correction data. Since the data is generated, the difference in whiteness due to the difference in material between the first white reference member and the second white reference member is corrected, and accurate shading correction can be performed.

  Further, the light amount temporal change data is generated by the difference between the initial second white reference member reading area data and the correction second white reference member reading area data, and the second shading correction is also performed using the light amount temporal change data. Since data is generated, the second white reference member, which also serves as a conveying means such as a roller and a belt, is not affected by dirt, so that accurate shading correction that is not affected by the use state can be performed. .

  (3) In the invention described in claim 3, in the above (2), the control means, when the difference between the fouling data and the light amount temporal change data is not less than a predetermined level, the reading area of the second white reference member It shows that there is dirt or a service call request.

  As a result, the light amount temporal change data is generated by the difference between the initial second white reference member reading area outside data and the corrected second white reference member reading area outside data, and the second shading is also performed using the light amount temporal change data. Since correction data is generated, it is in a state where it is not affected by dirt on the second white reference member that also serves as a conveying means such as a roller and a belt, so it is possible to perform accurate shading correction that is not affected by the use state Further, when the dirt of the second white reference member exceeds a predetermined state, a notification or warning can be displayed to the user.

  (4) In the invention according to claim 4, in the above (1) to (3), the control means averages the white reference original first data obtained by reading the third white reference member by the first reading means. Then, the sensitivity correction between the first reading unit and the second reading unit is executed based on the difference between the average value of the white reference original data obtained by reading the third white reference member by the second reading unit.

  As a result, uniform reading sensitivity can be realized between reading means having different reading formats, such as a first reading means having a movable reading opening and a second reading means having a fixed reading opening. Thus, good image reading is realized.

  In the above (2) to (3), the second white reference member is obtained by correcting the white reference document data obtained by reading the third white reference member by the second reading means with the light amount temporal change data. Sensitivity correction can be realized without being affected by dirt.

  The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the drawings. It should be noted that even an image reading apparatus that reads the contents of a document as image information by a document reading unit (scanner), generates image data, and outputs the image data. Even in an image forming apparatus (copying apparatus) having a function of reading and copying contents as image information, the contents of a transmission object (original) are read as image information by an original reading means (scanner), and a communication line The embodiment of the present invention can be applied even to an image transmission apparatus (facsimile apparatus) having a function of transmitting via a network.

  In this embodiment, an image reading apparatus having a function of reading images on both sides at a time and generating image data on both sides while conveying a document, that is, reading a solid-state image sensor having a plurality of pixels in the main scanning direction. It has an element, and the original is moved in the sub-scanning direction with respect to the reading element, so that two-dimensional reading (sheet-through reading) in the main scanning direction and the sub-scanning direction is performed on both sides of the original. It is intended for an image reading apparatus or an image forming apparatus having a function.

<Mechanical configuration of image reader>
First, the mechanical configuration of the image reading apparatus of this embodiment will be described with reference to FIG. Here, an image reading apparatus having a function of reading images on both sides of a document while generating a document and generating image data on both sides is used as a specific example of this embodiment.

  Here, the document d placed on the document placement unit 11 of the automatic document feeding unit (ADF) 10 is sent out by the feed roller 12a, and separated and conveyed by the separation roller 12b. Then, the document d is further conveyed by the registration roller 12c under posture control and timing control. Further, the document d is transported around the platen roller 13, and is discharged to a discharge tray 16 through a transfer roller 14 and a discharge roller 15 as backup rollers.

  In addition, the conveyance roller 14 is provided in the reading position of the 2nd reading part 20B so that it may mention later, and also serves as the 2nd white reference member. That is, the second white reference member is disposed at the reading position of the second reading unit 20B, and operates as a backup roller that drives the document while keeping the document in close contact with the second reading unit 20B when the document is being conveyed. At the same time, the surface is read by the second reading unit 20B in a state where no document exists.

  The image reading unit 20 includes a first reading unit 20A serving as a first reading unit having a movable reading opening for reading the first surface of the conveyed document, and a second surface of the conveyed document. It is comprised with the 2nd reading part 20B as a fixed 2nd reading means to read. The first reading unit 20A and the second reading unit 20B respectively read the first side and the second side of the document conveyed at the same time, and any of them may be arranged on the upstream side. . Therefore, contrary to FIG. 2, there is no problem even if the second reading unit 20B is arranged on the upstream side.

  Here, in the first reading unit 20A, the original surface of the original d is irradiated by the light source 23, and the reflected light is CCD (photoelectric conversion means) via the imaging optical system 25 via the mirrors 24a, 24b and 24c. An image is formed on the light receiving surface of the reading element 26. That is, here, the light source 23, the mirrors 24a, 24b, 24c, the optical system having the imaging optical system 25 and the CCD 26, and the optical system driving means (not shown) constitute the first reading unit 20A. . Here, the light source 23 is a light source composed of a rod-shaped xenon lamp having a longitudinal direction in the main scanning direction.

  In FIG. 2, when the document d is placed on the platen glass 21 with the reading surface facing downward, the optical system scans along the platen glass 21 and reads an image on one side of the document. I do. The first reading unit 20A includes movable scanning units U1 and U2 that constitute a movable reading opening.

  When the document d is automatically fed by the ADF 10 and rotates around the platen roller 13, the first surface of the document is read with the light source 23 and the mirror 24 a moving under the second platen glass 22. Is called. The read image data of the document d is sent from the CCD 26 to an image processing unit (not shown). In this state, in the first reading unit 20A, the movable scanning units constituting the movable reading opening remain at the positions indicated by U1 'and U2'.

  The second reading unit 20B is in close contact with a document by a CIS (contact image sensor) composed of a linear light source such as an LED (light emitting diode) or a xenon lamp and a line sensor composed of a CCD, and reads an image. This is a second reading unit of the mold, and is a fixed second reading unit that reads the second surface of the conveyed document.

  When the document d is automatically fed by the ADF 10 and rotates around the platen roller 13, the second reading unit 20B reads the second surface of the document d in parallel with this. The read image data of the document d is sent from the second reading unit 20B to an image processing unit (not shown).

In this way, the original d from which the images on the first side and the second side are read in parallel is stacked on the paper discharge tray 16.
A first white reference member 27 made of YUPO paper having a uniform white density is provided in the vicinity of the platen glass 21. Prior to the reading of the original, the amount of light in the main scanning direction at the first reading unit 20A is obtained from the image data obtained by reading the light source 23 and the mirror 24a under the first white reference member 27. Light amount distribution data representing a difference (light amount distribution) is collected, and first shading correction data for correcting the light amount distribution is generated.

  The transport roller 14 as the second white reference member 29 is provided at the reading position of the second reading unit 20B, and is configured by a white rubber roller or the like. In addition, if it is a belt-shaped conveyance part, it is comprised with the white belt. The second white reference member 29 only needs to be painted or coated at least with a white surface.

  Since the second white reference member 29 is disposed at the reading position of the second reading unit 20B, when the document is being transported, the second white reference member 29 is driven to transport while keeping the document in close contact with the second reading unit 20B. While operating as a roller, the surface is read by the second reading unit 20B in a state where no document exists. Prior to reading the original, light amount distribution data representing a difference in light amount (light amount distribution) in the main scanning direction in the second reading unit 20B is collected from the image data obtained by reading the second white reference member 29. Then, second shading correction data for correcting this light quantity distribution is generated.

  Since the second white reference member 29 is also used as the transport roller 14, and is made of a material such as rubber having a friction coefficient suitable for transporting the document, the whiteness is different from that of the first white reference member 27. Is different. In addition, there is a possibility that dirt is attached to the second white reference member 29 as the document is conveyed. Therefore, as will be described later, accurate shading correction is realized by the characteristic processing of this embodiment.

  The second reading unit 20B and the second white reference member 29 are both configured to be larger than the maximum reading width of the document, and the second reading unit 20B reads the outside of the reading area of the second white reference member 29. Initial second white reference member reading area data is generated. Further, when a white reference document as a third white reference member made of a material having the same whiteness as that of the first white reference member is read by the second reading unit 20B, white reference document data is generated.

<Electrical configuration of image reader>
FIG. 1 is a block diagram showing a detailed configuration in the image reading apparatus according to the first embodiment of the present invention. In FIG. 1, the periphery of the portion necessary for the description of the operation of the present embodiment is mainly described, and other portions known as the image reading apparatus are omitted.

  100 includes an image reading apparatus having a function of reading images on both sides at a time and generating image data on both sides while conveying an original, that is, a first reading unit 20A and a second reading unit 20B, and a sheet An image reading apparatus having a function of executing through-type reading on both sides of a document.

  Further, the image reading apparatus 100 collects light amount distribution data indicating a difference in light amount in the main scanning direction included in image data obtained by reading the first white reference member and the second white reference member, and the light amount distribution. It has a function of calculating shading correction data for making the light quantity distribution uniform on both sides based on the data, and executing shading correction on the image data on both sides of the document based on the shading correction data.

In the image reading apparatus 100, reference numeral 101 includes a CPU or the like, and is a control unit as a control unit that controls each unit.
The control unit 101 sets initial second white reference member reading data obtained by reading the reading area of the second white reference member with the second reading unit 20B and whiteness equivalent to that of the first white reference member. Whiteness correction data based on the difference between pixels at the same position with the white reference original data obtained by reading the white reference original as a third white reference member that does not constitute the image reading apparatus with the second reading unit 20B. And the control for generating the second shading correction data from the second white reference member reading data and the whiteness correction data at the time of correction is executed.

  In addition, the control unit 101 outputs the initial second white reference member reading area outside data obtained by reading the reading area outside the second white reference member at the initial time by the second reading unit 20B, and the second white color when correction data is generated. Control is performed when light amount change data is generated from the difference from the corrected second white reference member reading area data obtained by reading the outside of the reading area of the reference member by the second reading unit 20B.

  And this control part 101 performs control at the time of producing | generating 2nd shading correction data from 2nd white reference member reading data at the time of correction | amendment, whiteness correction data, and light quantity change data.

  In addition, the control unit 101 outputs the initial second white reference member reading area outside data obtained by reading the reading area outside the second white reference member at the initial time by the second reading unit 20B, and the second white color when correction data is generated. From the difference from the corrected second white reference member reading area data obtained by reading the outside of the reading area of the reference member by the second reading unit 20B, light amount temporal change data is generated, Initial second white reference member reading data (initial second white reference member reading area data) obtained by reading the reading area in the second reading unit 20B and the reading area of the second white reference member at the time of generating correction data Correction second white reference member reading data (corrected second white reference member reading area data) obtained by reading the second reading unit 20B If the difference between the contamination data and the light amount temporal change data is equal to or higher than a predetermined level, contamination is generated in the reading area of the second white reference member, or Then, control for displaying the service call request on the display unit is executed.

  Further, the control unit 101 is obtained by reading the average value of the first white reference original data obtained by reading the third white reference member by the first reading unit and reading the third white reference member by the second reading unit. The control for executing sensitivity correction between the first reading unit and the second reading unit is executed based on the difference from the average value of the white reference original data.

  Reference numeral 111 denotes an electrical component of the first reading unit 20A, which corresponds to an image sensor, a drive circuit, or the like of the first reading unit 20A. Reference numeral 112 denotes an electrical component of the second reading unit 20B, which corresponds to an image sensor, a drive circuit, or the like of the first reading unit 20B.

  Reference numeral 121 denotes an A / D conversion unit that converts a read analog signal of the first reading unit 111 into digital data. Reference numeral 122 denotes an AD converter that converts the analog signal read by the second reader 112 into digital data.

  A first image processing unit 131 performs various image processing on the first image data read by the first reading unit 111 and generated by the AD conversion unit 121. Reference numeral 132 denotes a second image processing unit when various image processing is performed on the second image data read by the second reading unit 112 and generated by the AD conversion unit 122.

  A first data memory 141 stores first shading correction data. 142 is a second data memory, initial second white reference member reading data (initial second white reference member reading area data, initial second white reference member reading area data), correction second white reference member reading data. (Second white reference member reading area data during correction, second white reference member reading area data during correction), white reference original data, whiteness correction data, light quantity change data, contamination data, second shading correction data Stored.

Reference numeral 151 denotes a first shading correction unit that performs shading correction on the first image data using the first shading correction data.
Reference numeral 152 denotes a second shading correction unit, which uses the second shading correction data generated based on the second white reference member reading area data at the time of correction, the white reference original data, the whiteness correction data, and the light amount temporal change data. Shading correction is applied to the two image data.

  An image memory 160 stores image data subjected to various image processing and shading correction. The image data is transferred to an external device based on the control of the control unit 101 via an interface (not shown) as a communication unit. Are output.

  A display unit 180 of the image reading apparatus displays various states or various messages with characters, numerical codes, pictograms, and the like based on the control of the control unit 101. Alternatively, the display unit 180 displays or informs by flashing sound or light as necessary.

In this embodiment, the “first shading correction data” is generated from the first white reference member reading data.
The “second white reference member reading area data” is generated by reading the reading area of the second white reference member 29 arranged at the reading position of the second reading unit 20B by the second reading unit 20B. . If the reading time is the initial adjustment time, the data is “initial second white reference member reading area data”, and if the reading time is the correction data generation time, “correction second white reference member reading area”. Data ".

  Further, the “second white reference member reading area outside data” indicates that when the second reading unit 20B and the second white reference member 29 are both configured to be larger than the maximum reading width of the original, the second white reference member. 29 outside the reading area is read and generated by the second reading unit 20B. In addition, if the reading time is the initial adjustment time, it is “initial second white reference member reading area data”, and if the reading time is when correction data is generated, “correction second white reference member reading area”. "Outside data".

  Note that in the actual apparatus, the second white reference member 29 arranged at the reading position of the second reading unit 20B is read by the second reading unit 20B. And “second white reference member reading data” in a state where “second white reference member reading area outside data” is combined are generated. If the reading time is the initial adjustment time, it is “initial second white reference member reading data”, and if the reading time is correction data generation, “correction second white reference member reading data”. Become.

  The “white reference document data” is data generated by reading the white reference document as the third white reference member having the same whiteness as the first white reference member 27 by the second reading unit 20B. It can also be referred to as “third white reference member reading data”.

  The “whiteness correction data” is generated from the difference between pixels at the same position in the initial second white reference member reading data (initial second white reference member reading area data) and the white reference document data.

  The “light quantity aging data” is the initial second white reference member reading out-of-region data obtained by reading the second reading unit 20B outside the reading region of the second white reference member at the initial time, and the correction data when the correction data is generated. The second white reference member is generated from the difference from the second white reference member reading area outside data obtained by reading the outside of the reading area of the two white reference members by the second reading unit 20B.

  Further, the “dirt data” is initial second white reference member reading data (initial second white reference member reading area data) obtained by reading the reading area of the second white reference member by the second reading unit 20B at the initial stage. ) And correction second white reference member reading data (correction second white reference member reading area data) obtained by reading the reading area of the second white reference member by the second reading unit 20B when generating correction data. It is generated from the difference.

  The “second shading correction data” is generated from the corrected second white reference member reading data and the whiteness correction data. Alternatively, the “second shading correction data” is generated from the corrected second white reference member reading data, the whiteness correction data, and the light amount temporal change data.

<Operational state of the first embodiment>
Hereinafter, the operation of the image reading apparatus according to the first embodiment will be described in detail with reference to the characteristic diagram of the light quantity distribution in FIG. 3 and the flowcharts in FIGS. 4 is a flowchart at the time of initial operation at the first reading unit 20A, FIG. 5 is a flowchart at the time of initial operation at the second reading unit 20A, and FIG. 6 is a flowchart at the time of initial operation at the second reading unit 20A. It is.

(1) Generation of first shading correction data and execution of correction:
In the image reading apparatus as described above, the operation of the first reading unit 20A during the initial operation will be described with reference to the flowchart of FIG.

  When the power of the image reading apparatus 100 is turned on (S1 in FIG. 4), the control unit 101 shifts to the initial adjustment mode (I) (S2 in FIG. 4) and initializes each unit of the first reading unit 20A. Here, in the initial adjustment mode (I), in order to acquire the first shading correction data, the light source 23 is turned on, and the optical unit U1 (see FIG. 2) is moved directly below the first white reference member 27 ( FIG. 4S3).

  Then, in accordance with an instruction from the control unit 101, the first white reference member 27 is read to obtain image data W1n in a state where the light source 23 and the mirror 24a are moved below the first white reference member 27 (S4 in FIG. 4). .

  Here, since the image data W1n is executed by, for example, the first reading unit 20A having 7400 reading elements, n means a pixel number of 1 to 7400.

  Then, from the image data obtained by reading the first white reference member, the control unit 101 calculates light amount distribution data representing a light amount difference (light amount distribution) in the main scanning direction in the first reading unit 20A. First shading correction data for correcting the light quantity distribution is generated (S5 in FIG. 4) and stored in the first data memory 141. That is, in the light amount distribution based on the image data obtained by reading the first white reference member 27, the peripheral light amount is reduced due to the cosine fourth law of various optical members, so the light amount is reduced at both ends as shown in FIG. Is generated, and first shading correction data for compensating for the decrease is generated.

  In the normal mode thereafter, the first shading correction unit 151 performs shading correction according to various image processing in the first image processing unit 131 based on the first shading correction data generated in this way. Execute.

(2) Generation of whiteness correction data:
In the image reading apparatus as described above, the operation of generating whiteness correction data during the initial operation of the second reading unit 20B will be described with reference to the flowchart of FIG. That is, the following operation (initial adjustment mode IIa) is performed before the second white reference member is contaminated by use.

  When the image reading apparatus 100 is turned on at a normal initial time such as during factory adjustment (S1 in FIG. 5), the control unit 101 shifts to the whiteness adjustment mode as an initial adjustment mode (IIa) for the second reading unit 20B. (S2 in FIG. 5), each unit of the second reading unit 20B is initialized.

  Here, in the initial adjustment mode (IIa), the purpose is to acquire the whiteness correction data ΔWn as a step before acquiring the second shading correction data. For this reason, first, the light source incorporated in the second reading unit 20B is turned on according to an instruction from the control unit 101 (S3 in FIG. 5).

  Then, in accordance with an instruction from the control unit 101, the second white reference member 29 is read in a state where the light source is turned on in this way, and the image data W2n is obtained (S4 in FIG. 5). Here, since the image data W2n is executed by, for example, the second reading unit 20B having 7400 reading elements, n means a pixel number of 1 to 7400.

  Then, from the image data W2n obtained by reading the second white reference member, the control unit 101 performs initial light amount distribution data representing a light amount difference (light amount distribution) in the main scanning direction in the second reading unit 20B. Two white reference member read data is calculated and stored in the second data memory 142 (S5 in FIG. 5).

  The light amount distribution by the image data W2n obtained by reading the second white reference member 29 is as shown by a solid line in FIG. 3C due to a sensitivity difference for each element group of the image pickup elements constituting the second reading unit 20B. In addition, although it is substantially constant within the element group, a stepwise change in signal value occurs due to a difference between element groups.

  For example, the image reading apparatus 100 corresponding to an A3 size document requires a reading width of 297 mm, and has a reading width of about 313 mm with some margin outside the document. In this case, although depending on the reading density, the second reading unit 20B has a number of elements of about 7400 elements, and therefore is configured by collecting element groups of about several hundred elements.

  Here, the control unit 101 displays the white reference document as a third white reference member having the same whiteness as the first white reference member 27 so as to place the white reference document on the document placement unit 11 of the ADF 10. To display. The white reference document is prepared in advance by the manufacturer of the image reading apparatus 100 so as to have the same whiteness as the material of the first white reference member 27 (for example, YUPO paper). It is desirable to attach it to the image reading apparatus 100.

  Then, in accordance with an instruction from the control unit 101, the white reference document placed on the document placement unit 11 is fed by the feed roller 12a with the light source in the second reading unit 20B turned on, and the second reading unit 20B The image data W3n is obtained by reading.

  Here, since the image data W3n is executed by, for example, the second reading unit 20B having 7400 reading elements, n means a pixel number of 1 to 7400.

  Then, from the image data obtained by reading the white reference document (third white reference member), the control unit 101 generates light amount distribution data representing the difference in light amount (light amount distribution) in the main scanning direction at the second reading unit 20B. Meaning white reference original data (third white reference member read data) is calculated and stored in the second data memory 142 (S6 in FIG. 5).

  The light quantity distribution by the image data (white reference original data) W3n obtained by reading this white reference original is shown in FIG. 3B due to the difference in sensitivity of each image sensor element group constituting the second reading unit 20B. As described above, although it is almost constant in the element group, a stepwise change in the signal value occurs due to a difference in each element group.

  This white reference original data is data obtained by reading a white reference original made of a material such as YUPO paper having the same whiteness as the first white reference member 27. Since the second white reference member 29 is made of a material such as white rubber, the whiteness is lower than that of the first white reference member 27 and the white reference original. As a result, as shown in FIG. 3C, the white reference original data and the initial second white reference member reading data have a level drop of ΔWn corresponding to the difference in whiteness.

  Then, the control unit 101 calculates whiteness correction data (ΔWn) representing a difference between pixels at the same position in the white reference document data W3n and the initial second white reference member read data W2n (S7 in FIG. 5).

That is, the whiteness correction data ΔWn is
ΔWn = W3n−W2n (1),
It can be expressed as.

  The initial second white reference member reading data is generated in the entire second white reference member 29, whereas the white reference original data is generated only in the reading region. Whiteness correction data is calculated as a difference between pixels at the same position of the in-region data and the white reference original data. Then, the control unit 101 stores the whiteness correction data in the second data memory 142 (S8 in FIG. 5).

  As described above, initial second white reference member reading data, white reference document data, whiteness correction in a state where initial second white reference member reading area data and initial second white reference member reading area data are combined. When the data is calculated and stored in the second data memory 142, the light source in the second reading unit 20B is turned off, and the process of the flowchart of FIG. 5 is terminated (S9 in FIG. 5).

  The above operation (generation of whiteness correction data ΔWn during the initial operation of the second reading unit 20B) is executed before the second white reference member is contaminated by use, and the data is used thereafter. To do.

(3) Generation of second shading correction data and execution of correction:
In the image reading apparatus as described above, the operation of generating and correcting second shading correction data during each operation of the second reading unit 20B will be described with reference to the flowchart of FIG.

  The following processing is executed every time the image reading apparatus is turned on for use, or when the power is turned on, such as when a predetermined time comes (after a predetermined number of readings have been executed) (correction). Time adjustment mode (IIb)).

  When the power of the image reading apparatus 100 is turned on (S1 in FIG. 6), the control unit 101 shifts to the second shading correction data generation mode as the adjustment mode (IIb) at the time of adjustment for the second reading unit 20B ( 6S2), each part of the second reading unit 20B is initialized.

  Here, in the adjustment mode (IIb) at the time of correction, as the stage of acquiring the second shading correction data, the whiteness correction data ΔWn calculated in the initial adjustment mode (IIa) already described and the light amount aging described later. The purpose is to generate second shading correction data with reference to the change data ΔL.

For this reason, first, the light source incorporated in the second reading unit 20B is turned on by an instruction from the control unit 101 (S3 in FIG. 6).
Then, in accordance with an instruction from the control unit 101, the second white reference member 29 is read in a state where the light source incorporated in the second reading unit 20B is turned on as described above, and the image data (second white reference member at the time of correction) is read. Read data) W4n is obtained (S4 in FIG. 6).

  Then, from the image data (second white reference member reading data at the time of correction) W4n obtained by reading the second white reference member, the control unit 101 determines the difference in light amount (light amount distribution) in the main scanning direction at the second reading unit 20B. The second white reference member reading data at the time of correction, which means the light amount distribution data representing (), is calculated and stored in the second data memory 142 (S5 in FIG. 6).

  The light quantity distribution by the image data (corrected second white reference member reading data) W4n obtained by reading the second white reference member 29 in the adjustment mode (IIb) at the time of correction constitutes the second reading unit 20B. Due to the sensitivity difference between the image sensor elements and the like, as shown by the solid line in FIG. 3 (d), the signal value is changed stepwise due to the difference between the element groups although it is almost constant within the element group. .

  Here, since the image data (second white reference member reading data at the time of correction) W4n is executed by, for example, the second reading unit 20B having 7400 reading elements, n is a pixel number of 1 to 7400. I mean. For example, the image reading apparatus 100 corresponding to an A3 size document requires a reading width of 297 mm, and has a reading width of about 313 mm with some margin outside the document. In this case, although depending on the reading density, the second reading unit 20B has a number of elements of about 7400 elements, and therefore is configured by collecting element groups of about several hundred elements.

  Further, by continuing to use the image reading apparatus 100, the light quantity of the light source gradually decreases, and the second white reference member 29 is also used as the transport roller 14, and therefore the second white reference member 29 is used as the document is transported. Dirt adheres to the reading area of the white reference member 29.

  Therefore, in the reading area, as shown in FIG. 3 (d), compared with the initial second white reference member reading data in the state without dirt (dashed line in FIG. 3 (d)), when the dirty state is corrected. The second white reference member reading data (solid line in FIG. 3 (d)) is lowered in level due to a drop in reflectance caused by dirt. Note that a slight decrease in level is also caused by a decrease in the amount of light from the light source.

  Further, since the second white reference member 29 is not contaminated outside the reading area, only the level reduction (light quantity change data ΔL) due to the light quantity reduction of the light source occurs. FIG. 3D shows a state in which the levels of ΔL1 and ΔL2 have decreased on both sides outside the reading area.

  That is, the control unit 101 reads out the initial second white reference member reading area data obtained by reading the outside of the reading area of the second white reference member at the initial time by the second reading unit 20B and the second white reference value when generating correction data. The light amount temporal change data ΔL is calculated from the difference from the corrected second white reference member reading area outside data obtained by reading the outside of the reading area of the member by the second reading unit 20B (S6 in FIG. 6).

For example, in the second reading unit 20B composed of 7400-pixel elements, when 100 edge portions are outside the reading region,
ΔL1 = ((W2 1 + W2 2 +... + W2100) − (W4 1 + W4 2 +... + W4100)) / 100 (2)

Similarly,
ΔL2 = ((W27301 + W27302 + ... + W27400)-(W47301 + W47302 + ... + W47400)) / 100 (3).

  Here, as W2n where n is the pixel number, the half-width numeric part immediately after W2 represents the pixel number. In addition, as W4n where n is the pixel number, the half-width numeric part immediately after W4 represents the pixel number.

And
ΔL = (ΔL1 + ΔL2) / 2 (4).
As described above, using the reading result outside the reading region of the second white reference member 29, the control unit 101 calculates the light amount temporal change data ΔL and stores it in the second data memory 142 (S7 in FIG. 6).

  The control unit 101 reads initial second white reference member reading data obtained by reading the reading area of the second white reference member 29 at the initial time (at the time before use by the user such as factory adjustment). Contamination data is generated from the difference between the second white reference member reading data at the time of correction and the second white reference member reading data at the time of correction obtained when the correction data is generated, and the amount of light is calculated from the contamination data. When the value obtained by subtracting the time-dependent change data ΔL is equal to or higher than a predetermined level, the display unit 180 is notified that the second white reference member 29 is contaminated or the service call request is displayed. indicate.

  Then, the control unit 101 obtains the white line data W5n for calculating the second shading correction data from the corrected second white reference member reading data W4n, the whiteness correction data ΔWn, and the light amount temporal change data ΔL. Generate as follows.

Here, W5n is
W5n = W2n + ΔWn−ΔL (5),
It can be expressed as.

  That is, the control unit 101 corrects the second white reference member reading data W4n (solid line in FIG. 3 (d)), whiteness correction data ΔWn (FIG. 5S7, FIG. 3 (c)), and light quantity change data ΔL ( The second shading correction data is calculated from FIG. 6S7 and FIG. 3D (equivalent to L2) (S8 in FIG. 6).

  As described above, when the light amount temporal change data ΔL and the second shading correction data are calculated and stored in the second data memory 142, the control unit 101 ends the process of the flowchart of FIG.

  In the normal mode thereafter, the second shading correction unit 152 performs shading correction according to various image processing in the second image processing unit 132 based on the second shading correction data generated in this way. Execute.

  When the light amount change data ΔL is small, the control unit 101 determines from the initial second white reference member reading data (FIG. 3C solid line) and the whiteness correction data ΔWn (FIG. 3C). It is also possible to calculate the second shading correction data.

Effect (1) obtained by the embodiment:
Here, the control unit 101 calculates the second shading correction data from the initial second white reference member read data (FIG. 3C, solid line) and the whiteness correction data ΔWn (FIG. 3C). Explain the effect.

  Here, the first shading correction data is generated by reading the first white reference member outside the original reading area and within the movable range of the reading opening of the first reading means, and is generated by the first reading means. The obtained image data is subjected to shading correction.

  In addition, as a result of the processing of the embodiment described above, the reading area of the second white reference member 29 arranged at the reading position of the second reading unit 20B is read by the second reading unit 20B, and the initial second white reference is obtained. Member reading data is generated. Further, the white reference document as a third white reference member made of a material having the same whiteness as the first white reference member is read by the second reading unit 20B, and white reference document data is generated. Also, whiteness correction data is generated from the difference between pixels at the same position in the initial second white reference member reading data and the white reference original data.

  Then, second shading correction data is generated from the corrected second white reference member reading data and whiteness correction data, and the image data generated by the second reading unit 20B is subjected to shading correction.

  As a result, the second white reference member 29 is arranged at the reading position of the second reading unit 20B, and also serves as a conveying unit such as a roller and a belt, so that the second reading unit 20B having a fixed reading opening is used. The installation difficulty of the two white reference member 29 is eliminated.

  Then, whiteness correction data is generated from the difference between the same position pixels of the white reference document data and the initial second white reference member read data by the third white reference member, and the second shading correction is performed using the whiteness correction data. Since data is generated, the difference in whiteness due to the difference in material between the first white reference member and the second white reference member 29 is corrected, and accurate shading correction can be performed. .

Effect (2) obtained by the embodiment:
Here, when the control unit 101 calculates the second shading correction data from the corrected second white reference member read data (solid line in FIG. 3D), the whiteness correction data ΔWn, and the light amount temporal change data ΔL. The effect of will be described.

  As a result of the processing in the embodiment as described above, the reading area of the second white reference member 29 arranged at the reading position of the second reading unit 20B is read by the second reading unit 20B, and the initial second white reference member reading is performed. Data is generated.

  The second reading unit 20B and the second white reference member 29 are both configured to be larger than the maximum reading width of the document, and the second reading unit 20B reads the outside of the reading area of the second white reference member 29. Initial second white reference member reading area data is generated.

  Further, the white reference document as a third white reference member made of a material having the same whiteness as the first white reference member is read by the second reading unit 20B, and white reference document data is generated. Also, whiteness correction data is generated from the difference between pixels at the same position in the initial second white reference member reading data and the white reference original data.

Further, the light amount temporal change data is generated based on the difference between the initial second white reference member reading area data and the corrected second white reference member reading area data.
Then, second shading correction data is generated from the corrected second white reference member reading data, whiteness correction data, and light amount temporal change data, and the image data generated by the second reading unit 20B is subjected to shading correction. Is done.

  As a result, the second white reference member 29 is arranged at the reading position of the second reading unit 20B, and also serves as a conveying unit such as a roller and a belt, so that the second reading unit 20B having a fixed reading opening is used. The installation difficulty of the two white reference member 29 is eliminated.

  Then, whiteness correction data is generated from the difference between the same position pixels of the white reference document data by the third white reference member and the initial second white reference member read data, and the second shading correction is performed using the whiteness correction data. Since the data is generated, the difference in whiteness due to the difference in material between the first white reference member and the second white reference member 29 is corrected, and accurate shading correction can be performed. .

  Further, the light amount temporal change data is generated by the difference between the initial second white reference member reading area data and the correction second white reference member reading area data, and the second shading correction is also performed using the light amount temporal change data. Since the data is generated, the second white reference member 29, which also serves as a conveyance unit such as a roller and a belt, is not affected by the dirt, so that accurate shading correction that is not affected by the use state can be performed. Become.

  Further, the control unit 101 generates fouling data from the difference between the initial second white reference member reading data and the corrected second white reference member reading data, and a value obtained by subtracting the light amount temporal change data ΔL from the fouling data. Is greater than or equal to a predetermined level, there is a contamination in the reading area of the second white reference member 29, or a service call request is displayed on the display unit 180, thereby affecting the use state. Not only can the correct shading correction not be performed, but also a notification or warning can be displayed to the user when the contamination of the second white reference member exceeds a predetermined state.

Other embodiment (1):
Further, the control unit 101 obtains the average value of the first white reference original data obtained by reading the third white reference member with the first reading unit 20A and the third white reference member with the second reading unit 20B. Sensitivity correction between the first reading unit 20A and the second reading unit 20B may be executed based on a difference from the average value of the obtained white reference original data. In this case, it can be dealt with by adjusting the amplification factor in one of the processing circuits.

  As a result, uniform reading sensitivity is realized between reading units having different reading formats, such as the first reading unit 20A having a movable reading opening and the second reading unit 20B having a fixed reading opening. As a result, good image reading is realized.

  The white reference original data obtained by reading the third white reference member with the second reading unit 20B is corrected with the light amount change data so that the second white reference member is not affected by dirt or the like. Sensitivity correction can be realized.

Other embodiment (2):
In the above embodiment, the image reading apparatus has been described as a specific example. However, in the case of an image forming apparatus provided with an image reading apparatus, the same control and processing are performed by executing the above-described control and processing. An excellent effect can be achieved.

1 is a functional block diagram illustrating an electrical configuration of an image reading apparatus according to an embodiment of the present invention. It is a block diagram which shows the mechanical structure of the image reading apparatus of embodiment of this invention. It is explanatory drawing which shows light quantity distribution of image reading. It is a flowchart which shows the processing operation at the time of image reading of embodiment of this invention. It is a flowchart which shows the processing operation at the time of image reading of embodiment of this invention. It is a flowchart which shows the processing operation at the time of image reading of embodiment of this invention.

Explanation of symbols

100 Image Reading Device 101 Control Unit 111 First Reading Unit 112 Second Reading Unit 121 AD Converter 122 AD Converter 131 First Image Processing Unit 132 Second Image Processing Unit 141 First Data Memory 142 Second Data Memory 151 First shading correction unit 152 Second shading correction unit 160 Image memory 180 Display unit

Claims (4)

An image reading apparatus having a function of reading images on both sides while conveying a document and generating respective image data on both sides,
An original conveying means for conveying an original;
First reading means having a reading opening movable to read the first surface of the conveyed document;
A first white reference member that is outside the reading area of the document and is provided in a movable range of the reading opening of the first reading unit, and is read by the first reading unit;
A fixed second reading means for reading the second surface of the conveyed document;
When the document is transported while being placed at the reading position of the second reading unit, the document is transported while being in close contact with the second reading unit, and when the document is not present, A second white reference member read by the second reading means;
First shading correction means for correcting shading of image data generated by reading by the first reading means with first shading correction data;
Second shading correction means for correcting the shading of the image data generated by reading by the second reading means with the second shading correction data;
Control means for generating the first shading correction data and the second shading correction data;
The control means includes
Initial second white reference member reading data obtained by reading the second white reference member with the second reading means at the initial stage, and a material having the same whiteness as the first white reference member, and the image reading Whiteness correction data is generated from the difference between pixels at the same position with the white reference original data obtained by reading the white reference original as a third white reference member that does not constitute the apparatus by the second reading unit,
Generating second shading correction data from the corrected second white reference member reading data and the whiteness correction data obtained by reading the second white reference member with the second reading means when generating correction data;
An image reading apparatus. An image reading apparatus having a function of reading images on both sides while conveying a document and generating respective image data on both sides,
An original conveying means for conveying an original;
First reading means having a reading opening movable to read the first surface of the conveyed document;
A first white reference member that is outside the reading area of the document and is provided in a movable range of the reading opening of the first reading unit, and is read by the first reading unit;
A fixed second reading means for reading the second surface of the conveyed document;
When the document is transported while being placed at the reading position of the second reading unit, the document is transported while being in close contact with the second reading unit, and when the document is not present, A second white reference member read by the second reading means;
First shading correction means for correcting shading of image data generated by reading by the first reading means with first shading correction data;
Second shading correction means for correcting the shading of the image data generated by reading by the second reading means with the second shading correction data;
Control means for generating the first shading correction data and the second shading correction data;
The second reading means and the second white reference member are both configured to be larger than the maximum reading width of the document,
The control means includes
The initial second white reference member reading area outside data obtained by reading the outside of the second white reference member reading area with the second reading means at the initial stage and the second white reference member reading area outside when the correction data is generated. From the difference from the correction-side second white reference member reading area data obtained by reading the second reading means, the light amount temporal change data is generated,
Initial second white reference member reading data obtained by reading the second white reference member with the second reading means at the initial stage, and a material having the same whiteness as the first white reference member, and the image reading Whiteness correction data is generated from a difference between pixels at the same position with the white reference original data obtained by reading the white reference original as a third white reference member that does not constitute the apparatus by the second reading unit, and correction data generation is performed. Generating second shading correction data from the corrected second white reference member reading data, the whiteness correction data, and the light amount temporal change data obtained by reading the second white reference member with the second reading unit.
An image reading apparatus. A display means for displaying various statuses is provided.
The control means includes
The initial second white reference member reading area outside data obtained by reading the outside of the second white reference member reading area with the second reading means at the initial stage and the second white reference member reading area outside when the correction data is generated. From the difference from the correction-side second white reference member reading area data obtained by reading the second reading means, the light amount temporal change data is generated,
Initial second white reference member reading data obtained by reading the second white reference member by the second reading means at the initial time, and reading the second white reference member by the second reading means at the time of generating correction data. From the difference between the corrected second white reference member reading data, fouling data is generated,
If the difference between the contamination data and the light intensity change data is equal to or greater than a predetermined level, it indicates that contamination has occurred in the reading area of the second white reference member, or a service call request is displayed. To
The image reading apparatus according to claim 2. The control means is obtained by reading the third white reference member with an average value of the white reference original first data obtained by reading the third white reference member with the first reading means and the second reading means. From the difference from the average value of the obtained white reference document data, sensitivity correction between the first reading unit and the second reading unit is executed.
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus.

Images