JP6201531B2 - Image reading device - Google Patents

Description

  The invention disclosed in this specification relates to a technique for generating white level data used for shading correction in an image reading apparatus.

Conventionally, when the image reading apparatus reads the reference plate and generates white level data used for shading correction, if there is dust or dust adhering to the reference plate, the white level data becomes abnormal, and the white level data When shading correction is performed using data, there arises a problem that vertical stripes occur in a read image read by the image reading apparatus.
In order to solve this problem, conventionally, in an image reading apparatus, a technique for reading at two different positions on a reference plate and comparing the two read signal values to generate white level data has been proposed (for example, Patent Document 1). In this apparatus, signal values at two reading positions are compared with each other, and the one having the maximum value is selected as white level data. Even if dust adheres to the surface of the white reference plate corresponding to one reading position and the corresponding one signal value is reduced from the reference value, the surface of the white reference plate corresponding to the other reading position is There is a low possibility that dust is attached, and there is a high possibility that the corresponding other signal value is maintained at the reference value. Therefore, by selecting the signal value that is the maximum value, the other signal value can be selected, and white level data can be generated appropriately.

JP 2002-27247 A

  If the cause of the abnormality in the white level data is only that the signal value is lowered due to dust as in Patent Document 1, the two signal values of a specific pixel are compared, and the signal value that is the maximum value is selected. Thus, the white level data can be appropriately generated. However, not only the signal value may decrease due to dust, but the white level data may be increased due to irregular reflection caused by scratches or dirt on the white reference plate in a relatively wide range. For example, there is a problem that white level data is generated by regarding an abnormal portion where the signal value has increased as normal.

  The present specification discloses a technique for appropriately generating white level data even if an abnormality occurs over a relatively wide range in the main scanning direction due to a change in color of the reference member, dirt, or the like.

An image reading apparatus disclosed in this specification includes a light source, a reading unit including a plurality of sensor chips each having a plurality of light receiving elements arranged in the main scanning direction, and a light receiving unit arranged in the main scanning direction; and the reference member, with respect to the reference member, in a sub-scanning direction perpendicular to prior Symbol main scanning direction, comprising: a moving unit for moving the reading unit, and a control unit, wherein the control unit of the reference member wherein the plurality of reading positions different in the sub-scanning direction, the reader their respective allowed to move, the pixels instructed to irradiate light to the light source in said read position is output for each of the light receiving element an acquisition process, each acquiring the data for each reading position, the pixel data for each light-receiving element obtained by the obtaining processing for each reading position, a determining process of determining whether normal or not by the sensor chip units , For each sensor chip, Select one pixel data groups of the sensor chip unit of which is determined to be normal by the cross-sectional process, it executes a generation process of generating the white level data for shading correction, the.

  In this image reading apparatus, when one pixel data is selected from a plurality of pixel data acquired at a plurality of reading positions and white level data for shading correction is generated, whether the pixel data is normal for each sensor chip. The pixel data determined to be normal is selected for each sensor chip. The sensor chip has a plurality of light receiving elements arranged in the main scanning direction and has a predetermined width in the main scanning direction. By selecting pixel data in units of sensor chips, white level data can be appropriately generated even if an abnormality occurs over a relatively wide range in the main scanning direction at the reading position of the reference member.

The image reading apparatus, in the control unit, the acquisition process, and the sub-scanning direction different from the first reading position and the second reading position of said reference member, their respective allowed to move the reading unit, the The instruction is given at the reading position, the first pixel data and the second pixel data output for each of the light receiving elements are obtained, and the absolute value of the difference value between the first pixel data and the second pixel data Detection processing for detecting a light receiving element having a value equal to or greater than a first specified value, and the determination processing includes a first pixel data group and second pixel data in sensor chip units including the light receiving elements detected by the detection processing. It is possible to determine whether any of the groups is normal, and to determine that both the first pixel data group and the second pixel data group in the sensor chip unit not including the light receiving element detected by the detection process are normal. good.

  In this image reading apparatus, a predetermined light receiving element is detected using a difference value between the first pixel data and the second pixel data, and it is determined whether or not the first pixel data group and the second pixel data group are normal. . By using the difference value between the first pixel data and the second pixel data, the white level data can be generated relatively easily.

In the image reading apparatus, in the control unit, the determination process includes a representative value of the first pixel data and a representative value of the second pixel data in all the light receiving elements of the sensor chip including the light receiving elements detected by the detection process. , And the first absolute value that is the absolute value of the difference between the first pixel data of the detected light receiving element and the representative value of the first pixel data, and the second pixel data of the detected light receiving element And a second absolute value that is an absolute value of a difference between the second pixel data and the representative value of the second pixel data, and determines that the pixel data group in the sensor chip of the pixel data having a larger absolute value is not normal. The pixel data group in the sensor chip having the smaller pixel data may be determined to be normal.

  In this image reading apparatus, the absolute value of the difference between the detected pixel data of the light receiving element and the representative value of the corresponding pixel data is compared, and which of the first pixel data group and the second pixel data group is normal? Judge whether or not. The difference between the pixel data and the representative value is caused by an abnormality such as dust or dirt adhering to the surface of the reference member, or a scratch on the surface of the reference member, and becomes a positive value depending on the type of the abnormality. Or may be negative. By using the absolute value of the difference between the pixel data and the representative value and comparing the absolute values, white level data can be appropriately generated regardless of the type of abnormality that has occurred on the surface of the reference member.

  In the image reading apparatus, in the control unit, when the determination process detects the plurality of light receiving elements in the sensor chip by the detection process when the determination is performed for each sensor chip, for each detected light receiving element, The absolute values of the differences are compared, and in any of the detected light receiving elements, when one of the first pixel data group and the second pixel data group is determined to be normal, the one pixel data group is It is determined that the other pixel data group is not normal, and it is determined that the first pixel data group is not normal in some of the detected light receiving elements. When it is determined that the pixel data group is not normal, it may be determined that neither the first pixel data group nor the second pixel data group is normal.

  In this image reading apparatus, when a plurality of light receiving elements are detected in one sensor chip, it is determined for each detected light receiving element whether the first pixel data group or the second pixel data group is normal. . For this reason, it is possible to suppress generation of white level data using a pixel data group obtained by reading a range including at least one abnormality on the surface of the reference member.

In the image reading apparatus, when the control unit further determines that neither of the first pixel data group and the second pixel data group is normal by the determination process, the sub-scanning direction different from the third reading position of the reference member relative to the first reading position and the second reading position, the causes the reading unit is moved, and the instruction in said read position, the output for each of the light receiving element Additional detection processing for acquiring the third pixel data is performed, and the detection processing is further performed in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. A light receiving element in which an absolute value of a difference value between the third pixel data and the first pixel data or the second pixel data is equal to or greater than a first specified value is detected, and the determination process is further performed in the detection process. It is determined whether or not the third pixel data group in the sensor chip unit including the light receiving element detected in this manner is normal, and the first pixel data group and the first pixel data group in the sensor chip unit not including the light receiving element detected by the detection process It is determined that both of the two pixel data groups are normal, and the generation process is performed by the determination process in the sensor chip that is determined that neither the first pixel data group nor the second pixel data group is normal . When it is determined that the three-pixel data group is normal, the third pixel data group in the sensor chip may be selected to generate white level data for shading correction.

  In this image reading apparatus, when it is determined that neither the first pixel data group nor the second pixel data group is normal in one sensor chip, the third pixel data group is further obtained by acquiring the third pixel data group. select. For this reason, it is possible to suppress generation of white level data using a pixel data group determined to be abnormal.

In the image reading apparatus, the detection process is performed by the control unit.
Furthermore,
The absolute value of the difference value between the third pixel data and the first pixel data or the second pixel data in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Detecting a light receiving element having a value equal to or greater than the first specified value,
The determination process includes
Furthermore,
Representative of third pixel data in all light receiving elements of the sensor chip including the light receiving elements detected by the detection processing in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Gets the value and the corresponding pixel data of the representative values respectively, the third absolute value is an absolute value of the difference between the representative value of the third pixel data and the third pixel data of the detected light receiving element, the first 1 absolute value or the second absolute value is compared to determine whether or not the third pixel data group is normal, and the generation processing includes both the first pixel data group and the second pixel data group. If the third pixel data group is determined to be normal by the determination process in the sensor chip determined to be not normal, the third pixel data group in the sensor chip is selected, and the shape of the third pixel data group is selected. It may be configured to generate white-level data for the loading correction.

  In this image reading apparatus, when it is determined that neither the first pixel data group nor the second pixel data group is normal, the third pixel data is further acquired, and the third pixel data group in the sensor chip is normal. When it is determined that the third pixel data group is selected, the third pixel data group is selected. Therefore, white level data can be generated using a pixel data group determined to be normal.

In the image reading apparatus, when the control unit determines that neither the first pixel data group nor the second pixel data group is normal by the determination process, the first reading is performed. position and the second reading position different from the third reading position, wherein by the reading unit moving the to the instruction by said read position, additional acquisition process for acquiring the third pixel data outputted for each of the light receiving element, The detection processing is further performed in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal, and the third pixel data and the first pixel data or the A light receiving element in which the absolute value of the difference value with respect to the second pixel data is equal to or greater than the first specified value is detected, and the determination process is further normal in both the first pixel data group and the second pixel data group. In the sensor chip determined to be, the representative value of the third pixel data and the representative value of the corresponding pixel data in all the light receiving elements of the sensor chip including the light receiving element detected by the detection process are respectively acquired and detected. A third absolute value that is an absolute value of a difference between the third pixel data of the light receiving element and a representative value of the third pixel data is compared with the first absolute value or the second absolute value, and the third pixel It is determined whether or not a data group is normal, and the generation process is performed in the third pixel by the determination process in a sensor chip that is determined that neither the first pixel data group nor the second pixel data group is normal. If the data group is determined to be not normal, the first absolute value, the second absolute value, and comparing the third absolute value, and selecting the pixel data group according to the smallest absolute value, Shede It may be configured to generate white-level data for the ring correction.

  In this image reading apparatus, when it is determined that neither the first pixel data group nor the second pixel data group is normal in one sensor chip, the third pixel data is further acquired. When it is determined that the third pixel data group in the sensor chip is not normal, the pixel data group with the smallest absolute value of the difference is selected. Therefore, when an abnormality over a relatively wide range in the sub-scanning direction occurs at a specific position in the main scanning direction on the surface of the reference member, and normal pixel data in the sensor chip is not acquired even if the reading position is changed, the pixel Data acquisition can be prevented from being repeated many times.

In the image reading apparatus, in the control unit, the detection process includes a plurality of light receiving elements in which an absolute value of a difference value between the first pixel data and the second pixel data is equal to or more than a first specified value, When detecting the plurality of light receiving elements continuous in the main scanning direction, the peak value of the absolute value of the difference value is detected in the continuous first continuous range, and the light receiving element corresponding to the peak value is detected, The determination process includes a fourth absolute value that is an absolute value of a difference between the first pixel data of the light receiving element corresponding to the detected peak value and a representative value of the first pixel data, and the detected peak value. The fifth absolute value , which is the absolute value of the difference between the second pixel data of the light receiving element corresponding to the second pixel data and the representative value of the second pixel data, and the fourth absolute value is greater than the fifth absolute value , Second pixel data group in the sensor chip Is determined to be normal, if the fourth absolute value is equal to or less than the fifth absolute value, it may be configured to first pixel data group in said sensor chip is determined to be normal.

  In this image reading apparatus, when the light receiving elements whose absolute value of the difference value between the first pixel data and the second pixel data is equal to or greater than the first specified value are continuous in the main scanning direction, the difference within the continuous range. The peak value of the absolute value is detected, and the absolute value of the difference in the light receiving element corresponding to the peak value is compared to determine whether the first pixel data group and the second pixel data group are normal. By performing the comparison with the light receiving elements corresponding to the peak value, it is possible to generate the white level data relatively easily as compared with the case of performing the comparison with each of the plurality of light receiving elements.

  In the image reading apparatus, in the control unit, the detection process further includes a second specified value that is smaller than the first specified value, in which an absolute value of a difference value between the first pixel data and the second pixel data is smaller than the first specified value. In a second continuous range in which a plurality of light receiving elements in which the absolute value of the difference value between the first pixel data and the second pixel data is equal to or greater than a second specified value are continuous in the main scanning direction. When the light receiving elements included in the second continuous range including the first continuous range belong to a plurality of sensor chips, each sensor chip of the plurality of sensor chips is within the second continuous range. The absolute value of the difference value may be detected and a light receiving element corresponding to the peak value may be detected.

Usually, in a sensor chip including only a light receiving element whose absolute value of the difference value between the first pixel data and the second pixel data is smaller than the first specified value, the first pixel data group and the second pixel data group in the sensor chip. Is determined to be normal, and it is not determined whether it is normal. However, the light receiving elements that are not included in the first continuous range and that are included in the second continuous range are light receiving elements in which the absolute value of the difference value between the first pixel data and the second pixel data is smaller than the first specified value. However, it is considered that the adjacent position of the abnormality over a relatively wide range of the reference member that causes the first continuous range is read. Therefore, in order to determine whether there is an influence of an abnormality over a relatively wide range, it is determined whether the first pixel data group and the second pixel data group in the sensor chip unit including the light receiving element are also normal. Better.
In this image reading apparatus, for all sensor chips belonging to the second continuous range, the peak value in the second continuous range is calculated for each sensor chip, and the first pixel data group and the second pixel data group are normal. Determine whether. Therefore, it is possible to determine whether or not the first pixel data group and the second pixel data group are normal even in the sensor chip corresponding to the abnormal adjacent position over a relatively wide range.

  According to the invention disclosed in this specification, white level data can be appropriately generated even if an abnormality occurs over a relatively wide range in the main scanning direction due to a change in color of the reference member, dirt, or the like. it can.

Schematic cross-sectional view of a multifunction machine The figure which shows the relationship between the light-receiving part of a 1st reading part, and a white reference board. Block diagram schematically showing the electrical configuration of the MFP Flow chart showing image reading process Flow chart showing white level data acquisition processing Flow chart showing peak pixel detection processing Flow chart showing abnormal white line identification processing Flow chart showing both line abnormality processing Flow chart showing white level data generation processing Graph showing pixel data D, difference value Diff, and white level data DS Graph showing difference value Diff

<One Embodiment>
An embodiment will be described with reference to FIGS. The multifunction device 1 is an example of an image reading apparatus, and can execute a plurality of modes such as a copy mode and a print mode in addition to a scan mode. In the following description, the lower right side of FIG. 1 is the front side (F) of the multifunction machine 1, the lower left side of the page is the left side (L) of the multifunction machine 1, and the upper side of the page is the upper side (U) of the multifunction machine 1. .

1. As shown in FIG. 1, the multifunction device 1 includes a cover portion 2 and a main body portion 3. A support member (not shown) is provided on the rear end side of the upper surface of the main body 3, and the cover 2 is connected to be rotatable about the support member. As a result, the cover portion 2 above the dotted line W can be displaced between a closed posture (see FIG. 1) covering the upper surface of the main body portion 3 and an open posture where the upper surface of the main body portion 3 is opened.

Cover 2, the supply tray 11, front sensor (hereinafter, F sensor) 12, a discharge tray 13, an automatic document feeder (Auto Document Feeder below, ADF) 14, a first 1ADF opposing member 15, flatbed (Flat, Bed Hereinafter, the pressing member 16 for FB), the 2nd reading part 17, the rear sensor (henceforth R sensor) 18, etc. are provided. In the cover portion 2, a transport path R is formed for returning a document sheet (not shown) from the supply tray 11 into a U shape and transporting it to the discharge tray 13.

  A plurality of original sheets before image reading can be arranged on the supply tray 11. The F sensor 12 detects the presence or absence of a document sheet on the supply tray 11 at a detection position RF on the leading end side (left end side) of the supply tray 11. The R sensor 18 detects the presence or absence of a document sheet at a detection position RR downstream of the detection position RF in the transport path R.

  The ADF 14 separates a plurality of document sheets placed on the supply tray 11 one by one, conveys them along the conveyance path R, and sequentially discharges them to the discharge tray 13. Specifically, the ADF 14 includes a supply roller 14A, a separation roller 14B, a separation pad 14C, a plurality of conveyance rollers 14D, a plurality of driven rollers 14E driven in pressure contact with the respective conveyance rollers 14D, and a plurality of guides for guiding the document sheet. It has member 14F etc.

  The supply roller 14A, the separation roller 14B, and the conveyance roller 14D are rotationally driven by a drive motor U1 (see FIG. 3). As a result, the supply roller 14A conveys the plurality of document sheets stacked on the supply tray 11 to the conveyance path R side, and the separation roller 14B and the separation pad 14C feed the plurality of document sheets one by one. Separated and sent out in the transport path R. The conveyance roller 14 </ b> D conveys the separated document sheet along the conveyance path R and discharges it onto the discharge tray 13.

  When the cover unit 2 is in the closed position, the first ADF facing member 15 faces the first reading unit 25 described later via the ADF glass 21A described later. The FB holding member 16 is provided on the lower surface side of the cover portion 2 and covers substantially the entire surface of the FB glass 21B described later when the cover portion 2 is in the closed posture. The second reading unit 17 is provided on the downstream side of the transport path R with respect to the first ADF facing member 15. The specific configuration of the second reading unit 17 is the same as that of the first reading unit 25 described later, and detailed description thereof is omitted.

  The main body 3 is formed in a box shape that is long in the left-right direction as a whole, and a platen glass 21 is disposed on the upper surface portion thereof. A partition member 22 is provided on the upper surface of the platen glass 21 at a position on the left side. The platen glass 21 is divided into two parts by the partition member 22. Hereinafter, the left part is referred to as ADF glass 21A, and the right part is referred to as FB glass 21B.

  A white reference plate 22 </ b> A and a black reference plate 22 </ b> B are provided on the lower surface of the partition member 22. The white reference plate 22A is a white member having a substantially uniform light reflectance on the facing surface facing the first reading unit 25, and the black reference plate 22B is the light reflectance of the facing surface facing the first reading unit 25. Is a generally uniform black member. The white reference plate 22A is an example of a reference member.

  As shown in FIG. 2, the white reference plate 22A has a predetermined width in the left-right direction, and the black reference plate 22B is disposed adjacent to the left front corner and the left rear corner. The right (R) end positions of the black reference plate 22B arranged at the left front corner and the left rear corner of the white reference plate 22A coincide with each other and are set to the reference position. A position moved about 5 mm to the right from the reference position is set as a first reading position R1 described later. Similarly, a position moved about 3 mm to the right from the reference position is set as a second reading position R2 described later, and a position moved about 1 mm to the right from the reference position is set as a third reading position R3 described later. ing.

  As shown in FIG. 1, a first reading unit 25, a device moving unit 26 (see FIG. 3), a second ADF facing member 27, and the like are provided in the main body unit 3. The first reading unit 25 faces the first ADF facing member 15 when the cover unit 2 is in the closed posture. The first reading unit 25 is a reading device having a CIS (Contact Image Sensor), and includes a light emitting unit 25A and a light receiving unit 25B. The first reading unit 25 is an example of a reading unit, and the light emitting unit 25A is an example of a light source.

  The light emitting unit 25A is configured by arranging a plurality of light emitting elements (such as light emitting diodes) in the main scanning direction Z1 corresponding to the front-rear direction of the main body unit 3. As shown in FIG. 2, the light receiving unit 25B is configured by arranging a plurality of sensor chips 28 in the main scanning direction Z1, and each sensor chip 28 has a plurality of pixels 29 in the main scanning direction Z1. Yes. The light receiving unit 25B receives the light emitted from the light emitting unit 25A and reflected by the document sheet using each pixel 29, and reads the document sheet. Each sensor chip 28 receives light emitted from the light emitting unit 25A and reflected by the white reference plate 22A using each pixel 29, and reads the white reference plate 22A. The pixel 29 is an example of a light receiving element.

Device moving unit 26, a first reading unit 25, the lower side of the platen glass 21, corresponding to the left-right direction of the main body 3, along the sub-scanning direction Z2 to Cartesian in the main scanning direction Z1 in other words relative It is possible to move (hereinafter, simply move). The device moving unit 26 rotationally drives a moving roller (not shown) by the moving motor U2 (see FIG. 3), and moves the first reading unit 25 in the sub-scanning direction Z2. The device moving unit 26 is an example of a moving unit.

  The first reading unit 25 is moved by the device moving unit 26 to a position that opposes the first ADF facing member 15, and performs a so-called ADF reading in which the ADF 14 reads the lower surface of the original sheet conveyed along the conveyance path R. Further, the first reading unit 25 reads the lower surface of the document sheet placed on the upper side of the FB glass 21B while moving the lower side of the FB glass 21B in the sub scanning direction Z2 by the device moving unit 26. A so-called FB reading is executed. Further, the first reading unit 25 is moved by the device moving unit 26 to a position that opposes the white reference plate 22A, and reads the white reference plate 22A at predetermined reading positions R1 to R3 (see FIG. 2).

  The second ADF facing member 27 faces the second reading unit 17 when the cover unit 2 is in the closed posture. The second reading unit 17 reads the upper surface of the document sheet conveyed by the ADF 14 to a position facing the second reading unit 17 on the conveyance path R. In addition to this, the main unit 3 includes various setting buttons, an operation unit 23 (see FIG. 3) that receives various commands from the user, and a display unit that displays the status of the multifunction machine 1 including an LED and a liquid crystal display. 24 (refer FIG. 3) etc. are provided.

2. As shown in FIG. 3, the multifunction device 1 includes an ASIC (Application Specific Integrated Circuit) 39, a ROM 36, and a RAM 37. The reading units 17, 25, the ADF 14, and the device moving unit 26 are included in these. Etc. are connected. As shown by a solid line 31 in FIG. 3, the one including the ASIC 3 9, the ROM 3 6, and the RAM 3 7 is an example of the control unit.

  The ASIC 39 includes a CPU 30 and a dedicated hardware circuit such as the image processing circuit 32. Various programs for controlling the operation of the multifunction device 1 are stored in the ROM 36, and the CPU 30 controls each unit according to the program read from the ROM 36, and will be described later using a hardware circuit as necessary. Processing such as image reading processing is executed. The ROM 36 also stores a first specified value K1, a second specified value K2, and the like which will be described later.

  Based on a command from the CPU 30, the reading units 17 and 25 cause the light emitting units 17A and 25A to emit light and read the original sheet and the white reference plate 22A. The reading units 17 and 25 are pixel data acquired by each pixel 29 of the plurality of sensor chips 28 arranged in the main scanning direction Z1 by the light receiving units 17B and 25B reading one line in the main scanning direction Z1 by one reading. The read image data that is a collection of. The read image data acquired by the reading units 17 and 25 is converted into read image data of a digital signal and stored in the RAM 27.

  The image processing circuit 32 performs edge detection processing such as binarization processing and enhancement processing on the read image data stored in the RAM 37 based on a command from the CPU 30. Further, the image processing circuit 32 executes various arithmetic processes using the density value of each pixel data of the read image data stored in the RAM 37 based on a command from the CPU 30.

3. Image Reading Process For example, when the user inputs an image reading instruction via the operation unit 23, the CPU 30 executes a reading control process shown in FIG. Based on the detection result of the F sensor 12, the CPU 30 executes ADF reading when determining that there is a document sheet on the supply tray 11, and executes FB reading when determining that there is no document sheet on the supply tray 11. To do.

  As shown in FIG. 4, when the image reading process is started, the CPU 30 first initializes the position of the first reading unit 25 in the sub-scanning direction Z <b> 2, which means the home position (hereinafter referred to as the first reading position R <b> 1). , HP) is detected (S2). In the HP detection process, the CPU 30 causes the first reading unit 25 to acquire read image data while moving the first reading unit 25 by the reference distance by the device moving unit 26. The CPU 30 detects a reference position where the white reference plate 22A and the black reference plate 22B are adjacent in the sub-scanning direction Z2 from the acquired read image data, and moves the first reading unit 25 to the first reading position R1.

  Next, the CPU 30 executes a light amount adjustment process (S4). In the light amount adjustment process, the CPU 30 repeats a plurality of readings in which the light emission time of the light emitting unit 25A is changed at the first reading position R1, and acquires read image data in subsequent processes from the acquired read image data. The light emission time of the light emitting unit 25A is determined. When completing the light amount adjustment process, the CPU 30 executes a white level data acquisition process (S6).

(White level data acquisition process)
FIG. 5 shows a flowchart of white level data acquisition processing. In the white level data acquisition process, the CPU 30 first acquires pixel data D1 (i) and D2 (i) (S22). Here, “i” means the pixel number of each pixel 29. In the light receiving unit 25B, each pixel 29 has a pixel number i of 1 to N (N: a natural number of 2 or more) along the main scanning direction Z1. Is set. Similarly, in the light receiving unit 25B, chip numbers M of 1 to K (K: a natural number of 2 or more) are set for each sensor chip 28 along the main scanning direction Z1.

  The CPU 30 causes the first reading unit 25 to read the white reference plate 22A at the first reading position R1 to obtain pixel data D1 (i). In addition, the CPU 30 causes the device moving unit 26 to move the first reading unit 25 to the second reading position R2, and causes the first reading unit 25 to read the white reference plate 22A at the second reading position R2 so that the pixel data D2 (i ) To get. The pixel data D1 (i) is an example of first pixel data, and the pixel data D2 (i) is an example of second pixel data.

  FIG. 10 shows the acquired pixel data D1 (i) and D2 (i). In FIG. 10, a range delimited by a dotted line indicates a range corresponding to each sensor chip 28. As shown in FIG. 10, the density value of the pixel data D does not become a constant value and fluctuates even within the same sensor chip 28 due to variations in the light receiving characteristics of each pixel 29. Further, the variation in the light receiving element of each pixel 29 becomes larger between different sensor chips 28, and the pixel data D obtained from the different sensor chips 28 shows a difference in density value called a chip gap CG.

The pixel data D also varies depending on the state of the facing surface of the white reference plate 22A facing the first reading unit 25. As shown in P1 and P3 of FIG. If it adheres, the density value decreases. Further, as shown at P2 in FIG. 10, if the facing surface of the white reference plate 22A is scratched, the reflection of light may change and the density value may increase. In the white level data acquisition process, even when an abnormality occurs on the facing surface of the white reference plate 22A, such as adhesion or scratches of dust, appropriate white level data that suppresses the influence of the abnormality is acquired. CP
When U30 acquires the pixel data D1 (i) and D2 (i), U30 executes a peak pixel detection process (S24).

(Peak pixel detection processing)
FIG. 6 shows a flowchart of peak pixel detection processing. In the peak pixel detection process, the CPU 30 first calculates a difference value Diff (i) between the pixel data D1 (i) and the pixel data D2 (i) for each pixel 29 (S42). The CPU 30 compares the absolute value of the calculated difference value Diff (i) with a first specified value K1 stored in advance in the ROM 36, and the absolute value of the difference value Diff (i) is equal to or greater than the first specified value K1. 29 is detected (S44). If the pixel 29 does not exist (S44: NO), the CPU 30 determines that there is no peak pixel (S46), and ends the peak pixel detection process.
Diff (i) = D2 (i) −D1 (i)

  On the other hand, when there is a pixel 29 in which the absolute value of the difference value Diff (i) is equal to or greater than the first specified value K1 (S44: YES), the CPU 30 sets the peak pixel in the pixel data D1 (i) and D2 (i). It is determined that there is (S47), and the process of detecting the peak pixel is continued. Specifically, the CPU 30 detects all the pixels 29 in which the absolute value of the difference value Diff (i) is not less than the first specified value K1 (S48). Next, the CPU 30 determines whether the detected pixel 29 includes a pixel 29 that is continuous in the main scanning direction Z1, that is, whether the detected pixel 29 includes a plurality of pixels 29 that have consecutive pixel numbers i. Judgment is made (S50).

  The CPU 30 makes the above determination for each detected pixel 29, and when there is no pixel 29 with consecutive pixel numbers i (S50: NO), the CPU 29 detects the pixel 29 as a peak pixel (see S52, i1, i4). ). On the other hand, when there are a plurality of pixels 29 with consecutive pixel numbers i (S50: YES), the CPU 30 expands the XI portion of FIG. 10 in FIG. In one continuous range RH1, the peak value of the absolute value of the difference value Diff (i) is detected. And CPU30 detects the pixel 29 corresponding to the detected peak value as a peak pixel (refer S54 FIG. 11 i3). The CPU 30 associates the detected pixel number j (= i1, i3, i4) of the peak pixel with the chip number M (= M1, M2, M4) of the sensor chip 28 including each peak pixel, and stores them in the RAM 37. (S56).

  When detecting the peak pixel, the CPU 30 determines whether there is a pixel to be detected as a peak pixel around the peak pixel. Specifically, the CPU 30 selects one of the peak pixels stored in the RAM 37 as the target peak pixel j (S58), and the absolute value of the difference value Diff (i) is the second value around the target peak pixel j. A pixel 29 having a specified value K2 or more and a second continuous range RH2 in which the pixel 29 is continuous in the main scanning direction Z1 are detected (S60). The second specified value K2 is a value smaller than the first specified value K1, and is stored in the ROM 36 in advance.

  As shown in the peak pixels i1 and i4 in FIG. 10, the pixel 29 having an absolute value of the difference value Diff (i) that is equal to or larger than the first specified value K1 is determined to be different from the peak pixel that is determined not to be continuous in the main scanning direction Z1. The pixel 29 in which the absolute value of the value Diff (i) is not less than the second specified value K2 may not be continuous in the main scanning direction Z1. In this case, the CPU 30 does not detect the second continuous range RH2. On the other hand, as shown by the peak pixel i3 in FIG. 11, the CPU 30 detects the second continuous range RH2 in the peak pixel detected from the first continuous range RH1. The second continuous range RH2 includes the first continuous range RH1 in addition to the target peak pixel j (= i3).

  The CPU 30 determines whether the pixel 29 included in the second continuous range RH2 belongs to the sensor chip 28 adjacent to the sensor chip 28 including the target peak pixel j (S62). As shown in FIG. 11, when the pixel 29 included in the second continuous range RH2 belongs to the adjacent sensor chip 28 (S62: YES), the CPU 30 detects the peak pixel also in the adjacent sensor chip 28.

  The CPU 30 detects the peak value of the absolute value of the difference value Diff (i) in the pixel 29 in the second continuous range RH2 of the adjacent sensor chip 28. And CPU30 detects the pixel 29 corresponding to the detected peak value as a peak pixel (refer S64 FIG. 11 i2). The CPU 30 associates the pixel number j (= i2) of the detected peak pixel with the chip number M (= M1) of the sensor chip 28 including each peak pixel and stores it in the RAM 37 (S66).

  When the process of S66 ends, or when the second continuous range RH2 is not detected (S62: NO), or the second continuous range RH2 is detected, the CPU 30 is adjacent to the second continuous range RH2. If the sensor chip 28 has not been reached (S62: NO), the processing for the target peak pixel j is terminated. The CPU 30 repeats the processing from S60 until all the peak pixels stored in the RAM 37 are selected as the target peak pixel j in the processing of S56 (S68: NO). When all the peak pixels stored in the RAM 37 are selected as the target peak pixel j (S68: YES), the CPU 30 ends the peak pixel detection process.

  When the peak pixel detection process ends, the CPU 30 returns to the white level data acquisition process shown in FIG. 5 and selects one of the sensor chips 28 as the target sensor chip M (S26). Next, the CPU 30 determines whether the target sensor chip M includes a peak pixel (S28). Specifically, the CPU 30 checks whether or not the chip number M stored in the RAM 37 in S56 and S66 includes the chip number of the target sensor chip M. When the target sensor chip M includes a peak pixel (S28: YES), the CPU 30 executes an abnormal white line specifying process (S24). That is, the abnormal white line specifying process is executed for each target sensor chip M.

(Abnormal white line identification processing)
FIG. 7 shows a flowchart of the abnormal white line specifying process. In the abnormal white line specifying process, the CPU 30 first calculates the average value J1 (M) of the pixel data D1 (i) of the target sensor chip M and the average value J2 (M) of the pixel data D2 (i) ( S72). The CPU 30 calculates the average value J1 (M) by averaging the pixel data D1 (i) (hereinafter referred to as pixel data D1 group in the target sensor chip M) in all the pixels 29 of the target sensor chip M. An average value J2 (M) is calculated by averaging pixel data D2 (i) in all the pixels 29 (hereinafter, pixel data D2 group in the target sensor chip M).

After calculating the average values J1 (M) and J2 (M), the CPU 30 uses the calculated average values J1 (M) and J2 (M) for each pixel 29 of the target sensor chip M to generate pixel data D1 ( i) Deviation Dev1 (i) and Dev2 (i) of D2 (i) are calculated (S74).
Dev1 (i) = D1 (i) -J1 (M)
Dev2 (i) = D2 (i) -J2 (M)

Next, the CPU 30 selects one of the peak pixels included in the target sensor chip M as the target peak pixel j (S76), the absolute value of the deviation Dev1 (j) at the target peak pixel j, and the deviation Dev2 (j) Is compared with the absolute value (S78). When the absolute value of the deviation Dev1 (j) is larger than the absolute value of the deviation Dev2 (j) (S78: YES), the CPU 30 determines that the pixel data D1 (j) of the target peak pixel j is abnormal (S80). On the other hand, when the absolute value of the deviation Dev1 (j) is equal to or smaller than the absolute value of the deviation Dev2 (j) (S78: NO), the CPU 30 determines that the pixel data D 2 (j) of the target peak pixel j is abnormal ( S82).

  When the target sensor chip M includes a plurality of peak pixels (i1, i2) like the sensor chip 28 with the chip number M1 shown in FIG. 10, the CPU 30 selects all the peak pixels as the target peak pixel j. Until (S84: NO), the processing from S76 is repeated. That is, when the target sensor chip M includes a plurality of peak pixels, the absolute value of the deviation Dev1 (i) is compared with the absolute value of the deviation Dev2 (i) for each peak pixel, and for each peak pixel, Either the pixel data D1 (j) or the pixel data D2 (j) of the target peak pixel j is determined to be abnormal.

  If all the peak pixels included in the target sensor chip M are selected as the target peak pixel j (S84: YES), the CPU 30 determines that the pixel data D2 of the target sensor chip M is abnormal in the pixel data D2 group. It is determined whether (i) exists (S86). When the pixel data D2 (i) determined to be abnormal does not exist in the pixel data D2 group in the target sensor chip M, as in the sensor chip 28 of the chip number M4 illustrated in FIG. When the pixel data D1 (j) is determined to be abnormal in all the peak pixels included in (S86: NO), the pixel data D1 group in the target sensor chip M is abnormal, and the pixel data D2 group in the target sensor chip M is It judges that it is normal (S88), and ends the abnormal white line specifying process.

  When the pixel data D2 (i) determined to be abnormal exists in the pixel data D2 group in the target sensor chip M (S86: YES), the CPU 30 further determines that the pixel data D1 group in the target sensor chip M is abnormal. It is determined whether the determined pixel data D1 (i) exists (S90). When the pixel data D1 (i) determined to be abnormal does not exist in the pixel data D1 group in the target sensor chip M as in the sensor chip 28 of the chip number M2 illustrated in FIG. When the pixel data D2 (j) is determined to be abnormal in all the peak pixels included in (S90: NO), the pixel data D1 group in the target sensor chip M is normal, and the pixel data D2 group in the target sensor chip M is It is determined that the abnormality is normal (S92), and the abnormal white line specifying process is terminated.

  On the other hand, the CPU 30, like the sensor chip 28 with the chip number M1 shown in FIG. 10, has pixel data D1 (i), which are determined to be abnormal in both the pixel data D1 group and D2 group in the target sensor chip M. When D2 (i) exists, that is, in some peak pixels included in the target sensor chip M, the pixel data D1 (j) is determined to be abnormal, and in the remaining peak pixels included in the target sensor chip M, When it is determined that the pixel data D2 (j) is abnormal (S90: YES), both the pixel data D1 group and D2 group in the target sensor chip M are determined to be abnormal (S94), and the abnormal white line specifying process is terminated. To do.

  When the CPU 30 completes the abnormal white line specifying process, the CPU 30 returns to the white level data acquisition process shown in FIG. 5 and checks whether both the pixel data D1 group and D2 group in the target sensor chip M are determined to be abnormal. (S32). When the CPU 30 determines that both the pixel data D1 group and D2 group in the target sensor chip M are abnormal, such as the sensor chip 28 with the chip number M1 shown in FIG. 10 (S32: YES), both lines are abnormal. The process is executed (S34). That is, both line abnormality processes are executed for each target sensor chip M.

(Both line abnormality processing)
FIG. 8 shows a flowchart of both line abnormality processing. In both line abnormality processing, the CPU 30 first acquires pixel data D3 (i) (S102). The CPU 30 causes the device moving unit 26 to move the first reading unit 25 to the third reading position R3, and causes the first reading unit 25 to read the white reference plate 22A at the third reading position R3 to obtain the pixel data D3 (i). Obtain (see FIG. 10). The pixel data D3 (i) is an example of third pixel data. In the both-line abnormality process using different sensor chips 28 as the target sensor chip M, when the pixel data D3 (i) has already been acquired, the pixel data D3 (i) may be used.

Next, the CPU 30 executes peak pixel detection processing using the pixel data D1 (i) and D3 (i) (S106). The peak pixel detection process using the pixel data D1 (i) and D3 (i) is executed according to the flowchart shown in FIG. In the peak pixel detection process using the pixel data D1 (i) and D3 (i), the CPU 30 calculates a difference value Diff2 (i) between the pixel data D1 (i) and D3 (i) (corresponding to S42). The absolute value of the difference value Diff2 (i) is compared with the first specified value K1 (corresponding to S44). When there is a pixel 29 in which the absolute value of the difference value Diff2 (i) is greater than or equal to the first specified value K1 (S44: equivalent to YES), the CPU 30 detects the peak pixel (corresponding to S52 and S54) and detects the detected peak. The pixel number x (= i1) of the pixel is stored in the RAM 37 (corresponding to S56). In the peak pixel detection process using the pixel data D1 (i) and D3 (i), the processes from S58 to S68 are not performed.
Diff2 (i) = D3 (i) −D1 (i)

  Next, the CPU 30 confirms whether or not a peak pixel is detected by the peak pixel detection process using the pixel data D1 (i) and D3 (i) (S108). When the peak pixel is detected in the above process (S108: YES), the CPU 30 further executes an abnormal white line specifying process using the pixel data D1 (i) and D3 (i) (S110).

The abnormal white line specifying process using the pixel data D1 (i) and D3 (i) is executed according to the flowchart shown in FIG. In the abnormal white line specifying process using the pixel data D1 (i) and D3 (i), the CPU 30 determines the average value J1 (M) of the pixel data D1 (i) of the target sensor chip M and the pixel data D3 (i ) Average value J3 (M) is calculated (corresponding to S72), and deviations Dev1 (i) and Dev3 (i) are calculated (corresponding to S74). If the average value J1 (M) and the deviation Dev1 (i) are already calculated in the abnormal white line specifying process of S30, the average value J1 (M) and the deviation Dev1 (i) are used. Also good.
Dev3 (i) = D3 (i) -J3 (M)

  The CPU 30 calculates the absolute value of the deviation Dev1 (x) and the absolute value of the deviation Dev3 (x) for each peak pixel x detected by the peak pixel detection process using the pixel data D1 (i) and D3 (i). Compare (equivalent to S78). When the absolute value of the deviation Dev3 (x) is equal to or larger than the absolute value of the deviation Dev1 (x) (S78: equivalent to NO), the CPU 30 determines that the pixel data D3 (x) of the target peak pixel x is abnormal (corresponding to S80). ). Then, the CPU 30 does not include pixel data D3 (i) determined to be abnormal in the pixel data D3 (i) (hereinafter referred to as pixel data D3 group in the target sensor chip M) in all the pixels 29 of the target sensor chip M ( S86: NO equivalent), the pixel data D3 group in the target sensor chip M is determined to be normal (refer to FIG. 10 equivalent to S88). On the other hand, when the pixel data D3 (i) determined to be abnormal exists in the pixel data D3 group in the target sensor chip M (S86: equivalent to YES), the CPU 30 determines that the pixel data D3 group in the target sensor chip M is abnormal. (S92, S94 equivalent).

  On the other hand, when the peak pixel is not detected in the peak pixel detection process using the pixel data D1 (i) and D3 (i) (S108: NO), the CPU 30 normalizes the pixel data D3 group in the target sensor chip M. (S111).

  The CPU 30 confirms whether or not the pixel data D3 group in the target sensor chip M is determined to be normal in the processing of S110 and S111 (S112). When it is determined that the pixel data D3 group in the target sensor chip M is normal, the CPU 30 ends the both pixel data group abnormality process. On the other hand, when the pixel data D3 group in the target sensor chip M is determined to be abnormal, that is, when the pixel data D group determined to be normal in the target sensor chip M is not acquired, the CPU 30 The pixel data D group that minimizes the absolute value of the deviation Dev (j) between the peak pixels j and x is selected from all the pixel data D1, D2, and D3 groups (S114).

  Specifically, in the target sensor chip M, the CPU 30 determines the absolute value of the deviation Dev1 (j) of the peak pixel j detected in the peak pixel detection process of S24, the absolute value of Dev2 (j), and the S106 The absolute value of deviation Dev1 (x) of peak pixel x detected in the peak pixel detection process is compared with the absolute value of Dev3 (x). The CPU 30 excludes the pixel data D group related to the deviation Dev having the largest absolute value among these deviations Dev. Then, the CPU 30 compares again the absolute values of the deviation Dev of the peak pixels j and x included in the remaining two pixel data D groups. The CPU 30 again excludes the pixel data D group related to the deviation Dev having the largest absolute value, and selects the remaining one pixel data D group. When the CPU 30 selects one pixel data D group, both line abnormality processing ends.

  When the CPU 30 completes both line abnormality processing, it executes white level data acquisition processing shown in FIG. In the white level data acquisition process, when the target sensor chip M does not include a peak pixel (S28: NO), like the sensor chip 28 with the chip number M3 shown in FIG. It is determined that both the pixel data D1 group and D2 group are normal (S29).

  When the processes of S29 and S34 are completed, or when one of the two pixel data groups D1 and D2 in the target sensor chip M is determined to be normal (S32: NO), the CPU 30 determines the target sensor chip M. The process for is terminated. The CPU 30 repeats the processing from S26 until all the sensor chips 28 included in the light receiving unit 25B are selected as the target sensor chip M (S36: NO). When all the sensor chips 28 included in the light receiving unit 25B are selected as the target sensor chip M (S36: YES), the CPU 30 executes white level data generation processing (S38).

(White level data generation processing)
FIG. 9 shows a flowchart of white level data generation processing. In the white level data generation process, the CPU 30 first selects one of the sensor chips 28 as the target sensor chip M (S122). Next, the CPU 30 determines whether or not the pixel data D1 group in the target sensor chip M is normal (S124). If the pixel data D1 group in the target sensor chip M is normal (S124: YES), the pixel data D1 A group is selected (S126).

  When the pixel data D1 group in the target sensor chip M is abnormal (S124: NO), the CPU 30 next determines whether the pixel data D2 group in the target sensor chip M is normal (S128). When the pixel data D2 group in the target sensor chip M is normal (S128: YES), the CPU 30 selects the pixel data D2 group (S130).

  When the pixel data D2 group in the target sensor chip M is abnormal (S128: NO), the CPU 30 further determines whether or not the pixel data D3 group in the target sensor chip M is normal (S132). When the pixel data D3 group in the target sensor chip M is normal (S132: YES), the CPU 30 selects the pixel data D3 group (S134).

  On the other hand, when the pixel data D3 group in the target sensor chip M is abnormal, that is, when all the pixel data D1, D2, and D3 groups in the target sensor chip M are abnormal (S132: NO), The pixel data D group selected in both line abnormality processing is selected (S136).

  When one pixel data D group in the target sensor chip M is selected in the processes of S126, S130, S134, and S136, the CPU 30 ends the process for the target sensor chip M. The CPU 30 repeats the processing from S122 until all the sensor chips 28 included in the light receiving unit 25B are selected as the target sensor chip M (S138: NO). When all the sensor chips 28 included in the light receiving unit 25B are selected as the target sensor chip M (S138: YES), the CPU 30 ends the white level data generation process and the white level data acquisition process.

  By the white level data generation process, the CPU 30 can collect the pixel data D group selected in units of sensor chip 28 and obtain the white level data DS (i) for shading correction (see FIG. 10). Specifically, the sensor chip 28 with the chip number M1 reads the pixel data D3 group from the pixel data D3 (i), and the sensor chip 28 with the chip numbers M2 and M3 has the pixel data D1 group from the pixel data D1 (i). The sensor chip 28 with the chip number M4 can acquire the white level data DS (i) for shading correction by reading the pixel data D2 group from the pixel data D2 (i).

  When completing the white level data acquisition process, the CPU 30 executes the image reading process shown in FIG. Next, in the image reading process, the CPU 30 executes a black level data acquisition process (S8). In the black level data acquisition process, the CPU 30 causes the device moving unit 26 to move the first reading unit 25 to the first reading position R1, and then performs reading to the first reading unit 25 with the light emitting unit 25A turned off. Let The CPU 30 acquires the read image data acquired by the above reading as black level data.

  Next, the CPU 30 executes a shading correction process (S10). In the shading correction process, the CPU 30 generates shading correction data by a known method using the white level data acquired in the white level data acquisition process and the black level data acquired in the black level data acquisition process.

  The CPU 30 executes a reading process after the shading correction process (S12). When executing ADF reading and the image reading instruction from the user includes a single-sided reading instruction, the CPU 30 reads the original sheet using the first reading unit 25. Further, when executing ADF reading, if the image reading instruction from the user includes a double-sided reading instruction, the CPU 30 reads the original sheet using the first reading unit 25 and the second reading unit. . When executing FB reading, the CPU 30 reads the original sheet using the first reading unit 25. In the present embodiment, a case of single-sided reading of ADF reading will be described.

  In the reading process, the CPU 30 causes the device moving unit 26 to move the first reading unit 25 to a position that opposes the first ADF facing member 15 (see FIG. 1), and the lower surface of the original sheet conveyed along the conveyance path R by the ADF 14. Is read by the first reading unit 25. The CPU 30 corrects the read image data acquired using the first reading unit 25 using the shading correction data generated by the shading correction process, and stores the corrected read image data in the RAM 37.

  When the CPU 30 detects that the original sheet has passed the detection position RR based on the detection result of the R sensor 18, after a predetermined time, the CPU 30 ends the reading by the first reading unit 25 and ends the reading of the original sheet. Then, the CPU 30 ends the reading process and ends the image reading process.

3. Advantages of this embodiment (1) In the multifunction device 1 of this embodiment, when generating white level data DS (i) for shading correction from pixel data D1 (i) and pixel data D2 (i), a sensor It is determined whether or not each chip 28 is normal, that is, for each pixel data D group, and the pixel data D group determined to be normal is selected for each sensor chip 28. The sensor chip 28 has a plurality of pixels 29 arranged in the main scanning direction Z1, and has a predetermined width wider than the width of the pixels 29 in the main scanning direction Z1. Therefore, as shown in P2 of FIG. 10, there is a relatively wide range of abnormalities on the facing surface due to a change in color or dirt on the facing surface of the white reference plate 22A, specifically, a plurality of widths in the main scanning direction Z1. Even when the vibration of the density value of the image data relating to the pixel 29 occurs, the white level data DS (i) can be generated while suppressing the influence.

(2) In the multifunction device 1 of the present embodiment, when determining whether each pixel data D group is normal or not, a peak pixel is detected from the absolute value of the difference value Diff (i), and a sensor chip having the peak pixel In 28, it is determined whether or not each pixel data D group is normal. By detecting the peak pixel from the absolute value of the difference value Diff (i), it is possible to detect the peak pixel relatively easily, and relatively easily determine whether each pixel data D group is normal. be able to.

(3) When determining whether or not each pixel data D group is normal, the multifunction device 1 of the present embodiment compares the absolute values of the deviation Dev (i) at the peak pixels. As shown in FIG. 10, when an abnormality occurs on the facing surface of the white reference plate 22A, the pixel data D (i) acquired from the range where the abnormality has occurred is acquired from the normal range due to the cause of the abnormality. It becomes larger or smaller than the pixel data D (i). Therefore, depending on the cause of the abnormality, the deviation Dev (i) calculated from the range in which the abnormality has occurred and the deviation Dev (i) calculated from the normal range may be reversed. In this multifunction device 1, the absolute values of the deviation Dev (i) are compared with each other. Therefore, the absolute value of the deviation Dev (i) calculated from the range where the abnormality has occurred is always set to a normal value regardless of the cause of the abnormality. The deviation Dev (i) calculated from the range can be larger than the absolute value, and it can be determined whether each pixel data D group is normal.

(4) In the multi-function device 1 of this embodiment, when a plurality of peak pixels are included in one sensor chip 28, the absolute values of the deviation Dev (i) are compared for each peak pixel, and each pixel It is determined whether data D group is normal. In the pixel 29 detected as the peak pixel, since the absolute value of the difference value Diff (i) is relatively large, there is an abnormality in one of the ranges corresponding to the pixel 29 in the first reading position R1 and the second reading position R2. Is considered to have occurred. When a plurality of peak pixels are included in one sensor chip 28, it is considered that there are a plurality of abnormalities. In the multi function device 1, it is determined whether or not each pixel data D group is normal for each peak pixel. Therefore, it is possible to determine whether each abnormality belongs to the first reading position R1 or the second reading position R2, and the white level data DS (i) using the pixel data D group acquired from the range including the abnormality. ) Can be suppressed.

(5) In the multifunction device 1 of the present embodiment, as a result of determining whether or not each pixel data D group is normal in one sensor chip 28, both the pixel data D1 group and the pixel data D2 group in the sensor chip 28 are determined. Is determined to be abnormal, the third pixel data D3 (i) is further acquired, and the pixel data D3 group in the sensor chip 28 can be selected. Therefore, it is possible to suppress generation of white level data using the pixel data D1 group and the pixel data D2 group that are determined to be abnormal.

(6) Specifically, it is determined whether or not the pixel data D3 group in the target sensor chip 28 is normal, and if it is determined to be normal, the pixel data D3 group in the sensor chip 28 is selected. . Thereby, the white level data DS (i) can be generated using the pixel data D group determined to be normal.

(7) On the other hand, if it is determined that the pixel data D3 group in the target sensor chip 28 is also abnormal, the pixel data D1 group in the sensor chip 28 is determined according to the absolute value of the deviation Dev (i). , One pixel data D3 group is selected from the pixel data D2 group and the pixel data D3 group. In the above case, that is, when an abnormality is found at substantially the same position in the main scanning direction Z1 in a plurality of pixel data D (i) with different reading positions, it is considered that these are the same abnormality. That is, it is conceivable that an abnormality over a relatively wide range in the sub-scanning direction Z2 occurs at a specific position in the main scanning direction Z1 on the facing surface of the white reference plate 22A. In such a case, the pixel data D can be acquired many times by selecting one pixel data D3 group from among the pixel data D1, the pixel data D2 group, and the pixel data D3 group in the sensor chip 28. Repeating can be suppressed.

  Then, when one pixel data D3 group is selected from the pixel data D1, group D2 group, and pixel data D3 group in the target sensor chip 28, the absolute value of the deviation Dev (i) is used as a reference. Thus, even when white level data is generated using the pixel data D group determined to be abnormal, the influence can be suppressed.

(8) When detecting the peak pixel from the difference value Diff (i), the multifunction device 1 of the present embodiment selects and selects the pixel 29 having the difference value Diff (i) equal to or greater than the first specified value K1. When the pixels 29 are continuous in the main scanning direction Z1, the pixel 29 whose difference value Diff (i) is a peak value is detected as a peak pixel. Therefore, when the absolute values of the deviation Dev (i) are compared to determine whether each pixel data D group is normal, all of the pixels 29 having the difference value Diff (i) equal to or greater than the first specified value K1. Therefore, it is not necessary to compare the absolute values of the deviation Dev (i) with each other, and the white level data DS (i) can be generated relatively easily.

(9) When the pixels 29 having the difference value Diff (i) equal to or greater than the first specified value K1 are continuous in the main scanning direction Z1, it is possible that an abnormality over a relatively wide range in the main scanning direction Z1 has occurred. Conceivable. In this case, it is conceivable that the influence of abnormality over a relatively wide range is exerted around the pixel 29 where the difference value Diff (i) is equal to or greater than the first specified value K1. In the MFP 1 of this embodiment, it is determined whether or not each pixel data D group is normal, and the pixel data D group is selected in units of sensor chips 28. The influence of the abnormality over a relatively wide range is If it extends beyond the range, it is preferable to determine whether or not the adjacent sensor chip 28 is normal.

  In the MFP 1 of the present embodiment, the influence on the periphery of an abnormality over a relatively wide range is detected using the second specified value K2 smaller than the first specified value K1, and the difference value Diff (i) is the second specified value. When the pixel 29 having the value K2 or more extends to the adjacent sensor chip 28, the peak pixel is also detected for the adjacent sensor chip 28. Therefore, when it is considered that the influence of the abnormality over a relatively wide range extends to the adjacent sensor chip 28, it can be determined whether or not the adjacent sensor chip 28 is normal.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.
(1) In the above embodiment, the description has been given using the multi-function device 1 having a plurality of functions such as a scan function, a copy function, and a print function. However, the present invention is not limited to this, and only a scanner function is provided. It may be an image reading device. Further, the multifunction device 1 may be configured to execute only one of ADF scanning and FB scanning, or may be configured to perform only single-sided scanning. In this case, the second reading unit 17 is not necessarily required.

(2) In the above embodiment, the multi function device 1 includes the ASIC 39 having the CPU 30, and the CP
The U30 has been described using an example in which a control unit that executes various processes such as an image reading process using a hardware circuit in the ASIC 39 as necessary is described, but the present invention is not limited to this. For example, if the CPU exists separately from the ASIC and the processing executed by the control unit may be executed by the CPU, the CPU does not exist in the ASIC, and the control unit is installed by a hardware circuit provided in the ASIC. Processing to be executed may be executed. Furthermore, the process which a control part performs may be performed by one or several CPU and ASIC.

(3) In addition, the program executed by the CPU 30 is not necessarily stored in the ROM 36, and may be stored in the CPU 30 itself or in another storage device.

(4) In the above embodiment, the description has been given using the example in which the HP detection process and the light amount adjustment process are performed in the image reading process, but the present invention is not limited to this. For example, if the HP detection process and the light amount adjustment process are performed in the first image reading process after the multifunction device 1 is turned on, the HP detection process and the light amount adjustment are performed while the multifunction device 1 is powered on. Processing may be omitted.

(5) Although the above embodiment has been described using an example in which the average value J (M) is used when calculating the deviation Dev (i), the present invention is not limited to this. For example, instead of the average value J (M), an intermediate value of the pixel data D1 (i) in all the pixels 29 of the sensor chip 28 may be used.

22A: White reference plate, 25: First reading unit, 25B: Light receiving unit, 26: Device moving unit, 28: Sensor chip, 29: Pixel, D: Pixel data, Dev: Deviation, Diff: Difference value, J: Average Value, DS: white level data, i: pixel number, M: chip number, j, x: peak pixel, R1 to R3: reading position,

Claims (9)

A reading unit having a light source and a plurality of sensor chips in which a plurality of light receiving elements are arranged in the main scanning direction, and a light receiving unit arranged in the main scanning direction;
A reference member;
And with respect to the reference member, in a sub-scanning direction perpendicular to prior Symbol main scanning direction, and a moving unit for moving the reading unit,
A control unit;
With
The controller is
The sub-scanning direction of the different reading position of said reference member, said reading unit their respective allowed to move, instructed to irradiate light to the light source in said read position, for each of the light receiving element An acquisition process for acquiring output pixel data for each reading position;
Wherein the pixel data for each light-receiving element obtained by the obtaining processing for each reading position, a determining process of determining whether normal or not by the sensor chip units,
For each sensor chip, a generation process for selecting one of the sensor chip unit pixel data determined to be normal by the determination process and generating white level data for shading correction;
An image reading apparatus that executes The image reading apparatus according to claim 1,
In the control unit,
The acquisition process includes
In the auxiliary scanning direction different from the first reading position and the second reading position of said reference member, said reading unit their respective allowed to move, the above indicated by said read position is output for each of the light receiving element 1 pixel data and 2nd pixel data are acquired,
Furthermore,
A detection process for detecting a light receiving element in which an absolute value of a difference value between the first pixel data and the second pixel data is equal to or greater than a first specified value;
Run
The determination process includes
Determining which one of the first pixel data group and the second pixel data group in the sensor chip unit including the light receiving element detected by the detection process is normal;
It is determined that both the first pixel data group and the second pixel data group in sensor chip units not including the light receiving element detected by the detection process are normal.
Image reading device. The image reading apparatus according to claim 2,
In the control unit,
The determination process includes
Obtaining a representative value of the first pixel data and a representative value of the second pixel data in all the light receiving elements of the sensor chip including the light receiving elements detected by the detection process,
A first absolute value which is an absolute value of a difference between the first pixel data of the detected light receiving element and a representative value of the first pixel data; a second pixel data of the detected light receiving element; and the second pixel. The second absolute value that is the absolute value of the difference from the representative value of the data is compared, the pixel data group in the sensor chip of the pixel data with the larger absolute value is determined to be not normal, and the smaller absolute value Determining that the pixel data group of the pixel data in the sensor chip is normal;
Image reading device. The image reading apparatus according to claim 3,
In the control unit,
The determination process includes
When a plurality of light receiving elements are detected in the sensor chip by the detection process when the determination is performed in units of the sensor chip, the absolute value of the difference is compared for each detected light receiving element,
In all the detected light receiving elements, when one of the first pixel data group and the second pixel data group is determined to be normal, the one pixel data group is determined to be normal, and the other pixel data group is determined. Is not normal,
When it is determined that the first pixel data group is not normal in some of the detected light receiving elements, and the second pixel data group is also not normal in the remaining detected light receiving elements, the first pixel data Determining that neither the group nor the second pixel data group is normal;
Image reading device. The image reading apparatus according to claim 4,
In the control unit,
Furthermore,
When the determination process determines that neither the first pixel data group nor the second pixel data group is normal, the sub-scanning direction of the reference member with respect to the first reading position and the second reading position the different third reading position, the allowed reading unit to move the, and the instruction in said read position, additional acquisition process for acquiring the third pixel data outputted for each of the light receiving element,
Run
The detection process includes
Furthermore,
The absolute value of the difference value between the third pixel data and the first pixel data or the second pixel data in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Detects a light receiving element having a value equal to or greater than the first specified value,
The determination process includes
Furthermore,
Determining whether or not the third pixel data group of the sensor chip unit including the light receiving element detected by the detection process is normal;
It is determined that both the first pixel data group and the second pixel data group in sensor chip units that do not include the light receiving element detected by the detection process are normal,
The generation process includes
In the sensor chip in which it is determined that neither the first pixel data group nor the second pixel data group is normal, if the third pixel data group is determined to be normal by the determination process, the sensor chip Selecting a third pixel data group to generate white level data for shading correction;
Image reading device. The image reading apparatus according to claim 5,
In the control unit,
The detection process includes
Furthermore,
The absolute value of the difference value between the third pixel data and the first pixel data or the second pixel data in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Detecting a light receiving element having a value equal to or greater than the first specified value,
The determination process includes
Furthermore,
Representative of third pixel data in all light receiving elements of the sensor chip including the light receiving elements detected by the detection processing in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Value and the representative value of the corresponding pixel data,
A third absolute value that is an absolute value of a difference between the detected third pixel data of the light receiving element and a representative value of the third pixel data is compared with the first absolute value or the second absolute value ; Determining whether the third pixel data group is normal;
The generation process includes
In the sensor chip in which it is determined that neither the first pixel data group nor the second pixel data group is normal, if the third pixel data group is determined to be normal by the determination process, the sensor chip Selecting a third pixel data group to generate white level data for shading correction;
Image reading device. The image reading apparatus according to claim 4,
In the control unit,
The detection process includes
Furthermore,
If it is determined by the determination process that neither the first pixel data group nor the second pixel data group is normal, the reading unit is moved to a third reading position different from the first reading position and the second reading position. was moved, and the instruction in said read position, additional acquisition process for acquiring the third pixel data outputted for each of the light receiving element,
Run
The detection process includes
Furthermore,
The absolute value of the difference value between the third pixel data and the first pixel data or the second pixel data in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Detecting a light receiving element having a value equal to or greater than the first specified value,
The determination process includes
Furthermore,
Representative of third pixel data in all light receiving elements of the sensor chip including the light receiving elements detected by the detection processing in the sensor chip determined that neither the first pixel data group nor the second pixel data group is normal. Value and the representative value of the corresponding pixel data,
A third absolute value that is an absolute value of a difference between the detected third pixel data of the light receiving element and a representative value of the third pixel data is compared with the first absolute value or the second absolute value ; Determining whether the third pixel data group is normal;
The generation process includes
In the sensor chip in which it is determined that neither the first pixel data group nor the second pixel data group is normal, the first absolute value when the third pixel data group is determined to be normal by the determination process Comparing the second absolute value and the third absolute value , selecting a pixel data group related to the smallest absolute value, and generating white level data for shading correction,
Image reading device. The image reading apparatus according to any one of claims 3 to 7,
In the control unit,
The detection process includes
When a plurality of light receiving elements in which the absolute value of the difference value between the first pixel data and the second pixel data is equal to or greater than a first specified value and the plurality of light receiving elements continuous in the main scanning direction are detected, Detecting a peak value of the absolute value of the difference value in a continuous first continuous range, detecting a light receiving element corresponding to the peak value;
The determination process includes
A fourth absolute value that is an absolute value of a difference between the first pixel data of the light receiving element corresponding to the detected peak value and a representative value of the first pixel data, and a light receiving element corresponding to the detected peak value When the fourth absolute value is larger than the fifth absolute value , the fifth absolute value that is the absolute value of the difference between the second pixel data of the second pixel data and the representative value of the second pixel data is compared . Determining that the second pixel data group is normal, and determining that the first pixel data group in the sensor chip is normal when the fourth absolute value is less than or equal to the fifth absolute value;
Image reading device. The image reading apparatus according to claim 8, wherein
In the control unit,
The detection process includes
Furthermore,
Detecting a light receiving element in which an absolute value of a difference value between the first pixel data and the second pixel data is equal to or more than a second specified value smaller than the first specified value;
A second continuous range in which a plurality of light receiving elements having an absolute value of a difference value between the first pixel data and the second pixel data equal to or greater than a second specified value is continuous in a main scanning direction, and the first continuous range When the light receiving elements included in the second continuous range including a plurality belong to a plurality of sensor chips, the absolute value peak of the difference value in the second continuous range for each sensor chip of the plurality of sensor chips. Detecting the value and detecting the light receiving element corresponding to the peak value,
Image reading device.