JP6571421B2 - Image reading apparatus and shading correction method - Google Patents

Description

  The present invention relates to an image reading apparatus and a shading correction method for reading an image of a document while conveying the document.

  In general, an image reading apparatus that reads an image of an original while conveying the original illuminates the original with a light source, collects reflected light from the original with a rod lens array or the like, and reads the image of the original with a line image sensor or the like. However, since there is unevenness in the light amount of the light source and the rod lens array and unevenness in the sensitivity of the line image sensor, there is a problem that a uniform image cannot be read as it is.

  Therefore, in order to enable reading of a uniform image, a line image is read when reading a document by using shading correction data generated based on an output signal when a white color reference member is read by a line image sensor. Image information obtained from the output signal of the sensor is corrected. When capturing the shading correction data used in this correction, the gain that optimizes the light amount adjustment that optimizes the light emission amount of the light source for illuminating the document and the amplification factor that amplifies the output signal of the line image sensor Adjustments are made.

  For example, a flatbed image reading apparatus moves a reading sensor (a combination of a light source, a lot lens array, and a line image sensor) to a reading position of a color reference member, reads the color reference member, and outputs the read output signal. Based on this, the shading correction data is generated. When reading a document, the reading sensor is moved to read the document.

  In Patent Document 1, a reading sensor (a combination of a light source, a lot lens array, and a line image sensor) housed in a reading unit is moved to a reading position of a color reference member, and the color reference member is read. A technique for generating shading correction data and performing shading correction has been proposed.

JP 2011-259509 A

  However, in the case of an image reading apparatus that moves the reading sensor, such as the flat bed type or the image reading apparatus of Patent Document 1, there is a possibility that the reading sensor may be inclined due to vibration of the movement of the reading sensor. For example, if the reading sensor is inclined when reading the color reference member, the incident angle of light from the light source that illuminates the color reference member changes. When the incident angle changes, the amount of light incident on the reading sensor changes, so that image information different from that when the reading sensor is not tilted is acquired.

  When shading correction data is generated from the different image information and shading correction is performed, shading correction cannot be performed normally, and unevenness tends to occur in the read image.

  The present invention provides an image reading apparatus and a shading correction method capable of performing highly accurate image correction based on color-based correction data.

An image reading apparatus according to the present invention is an image reading apparatus including a reading unit that reads a document at a document reading position, and is located at a position different from the document reading position, and the reading unit performs a color reference for performing shading correction. A member, a moving means for moving the reading means to the reading position of the original and the reading position of the color reference member, and an inclination of the optical axis of the reading means with respect to the normal direction of the original or the color reference member a tilt detection sensor for the image data of the document read by the document reading position a shading correction data for the shading correction by the reading means, said reading means in the reading position of the color reference member a data acquisition unit for acquiring the shading correction data by reading the color reference member by said tilt detection The inclination of the optical axis of said reading means in the original reading position detected by the sensor, on the basis of the difference between the inclination of the optical axis of said reading means in the reading position of the tilt detecting the color reference member detected by the sensor shading Correction value changing means for correcting the correction data.
According to this aspect of the present invention, it is possible to perform highly accurate image correction by correcting the white reference data based on the detection result of the tilt detection sensor.
In the image reading apparatus of the present invention, the correction value changing unit includes the inclination of the reading unit at the reading position of the color reference member detected by the inclination detection sensor, and the original reading position detected by the inclination detection sensor. The shading correction data is corrected based on the inclination of the reading means.

The image reading apparatus of the present invention is an image reading apparatus that reads an image of a document while conveying the document, and a reading unit that reads an image of the document at a document reading position and a position different from the document reading position. A reading unit comprising a white color reference member for the reading means to perform shading correction, and a moving mechanism for moving the reading means to the original reading position and the reading position of the color reference member, A moving unit that moves the reading unit to the original reading position and the reading position of the color reference member by moving the moving mechanism of the reading unit from the outside of the reading unit, and attached to the reading unit. The inclination of the reading means at the original reading position and the inclination of the reading means at the reading position of the color reference member can be detected. Generating shading correction data based on the detection sensor, the image information of the color reference member read by the reading means, and the inclination of the reading means at the reading position of the color reference member detected by the inclination detection sensor; And a shading correction unit that performs shading correction of the reading unit, and a correction value changing unit that corrects shading correction data of the reading unit based on an inclination detected by the inclination detection sensor. .
According to this aspect of the present invention, it is possible to perform highly accurate image correction by correcting the white reference data based on the detection result of the tilt detection sensor.

In the present invention described above, the correction value changing means may use the shading correction data based on a difference between the inclination of the reading means at the reading position of the color reference member and the inclination of the reading means at the original reading position. It is also possible to make a correction.
According to this aspect of the present invention, since the shading correction data is corrected based on the document reading position, more accurate shading correction can be performed.

In the present invention, there is provided an inclination means capable of changing the inclination of the reading means at the reading position of the color reference member, the reading means is inclined by the inclination means, and shading correction data at the inclination is generated. The shading correction data having an inclination that matches or is close to the inclination of the reading unit at the document reading position may be used as the shading correction data of the reading unit.
According to this aspect of the present invention, more accurate shading correction can be performed if the color reference member is tilted to obtain shading correction data.

Further, in the present invention has an inclination of the reading section as an initial value, to detect the inclination of the reading section in the document reading position by the inclination detection sensor after power-on, the document reading and the initial value The inclination of the reading means at the position is compared, and if the difference at the time of comparison is larger than an arbitrary threshold value, it is determined that the inclination is abnormal, and the reading is performed using an error display or warning means on the display means. It may be characterized by notifying the abnormality of the inclination of the means.
According to such an aspect of the present invention, the user can immediately perform the subsequent response by notifying of an error or the like according to the degree of inclination.

The image processing apparatus according to the present invention includes an image reading sensor that reads an image of a reading object, a color reference member that is disposed to face the image reading sensor, and an inclination detection sensor that detects the inclination of the image reading sensor. And correction means for correcting the correction reference data obtained by reading the color reference member by the image reading sensor based on the detection result of the tilt detection sensor.
According to the present invention, since the correction reference data can be corrected by the inclination of the image reading sensor, it is possible to perform highly accurate image correction based on the color reference correction data.

In the shading correction method of the present invention, the correction reference data is acquired by reading the color reference member facing the image reading sensor, the correction reference data is corrected based on the inclination detection data of the image reading sensor, and the image reading sensor The image data obtained by reading the object to be read is corrected based on the corrected correction reference data.
According to this aspect of the present invention, the image data read by the image reading sensor can be corrected based on the correction reference data considering the inclination of the image reading sensor, so that highly accurate image correction can be performed.

  According to the present invention, it is possible to realize an image reading apparatus and a shading correction method capable of performing highly accurate image correction based on color-based correction data. In particular, optimal shading correction data can be generated even when the reading sensor is tilted, and variations in characteristics of individual reading sensors can be corrected. Thereby, unevenness in the density of the read image can be suppressed.

1 is a schematic configuration diagram of an image reading apparatus according to an embodiment of the present invention. 2A and 2B are diagrams for explaining the movement of the image reading unit in FIG. 1, in which FIG. 1A shows a normal operation of the reading sensor, and FIG. 2B shows an operation when the reading sensor is tilted. FIG. 2 is an electrical block diagram of the image reading apparatus shown in FIG. 1. The flowchart regarding the calculation process of the inclination angle of a reading sensor. The flowchart figure regarding the production | generation of the data for shading correction | amendment. The flowchart figure regarding the production | generation of the data for shading correction | amendment. A numerical table of correction values x for correcting shading correction data.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic internal structure of an image reading apparatus according to an embodiment of the present invention as viewed from the side. This structure is an example of the structure of this invention, and is not restricted to this.

  In FIG. 1, an image reading apparatus 1 includes a pickup roller 2 that picks up a document D, a feeding roller 3 that feeds the document D picked up by the pickup roller 2 into the apparatus, and one sheet of the document D that has been picked up. And a separation roller 4 for separating them one by one.

  Further, on the downstream side of the separation roller 4, a registration roller (roller pair) 5 that is disposed in a pair at opposite positions and conveys the document D, and an upper surface of the document D that is conveyed by the registration roller 5 ( A reading unit 61 that reads image information on the front surface, a reading unit 62 that reads image information on the lower surface (back surface) of the conveyed document D, and a position that is disposed downstream of these reading units 61 and 62 and faces each other. A conveyance roller 7 that is arranged in a pair and conveys the document D is arranged.

  A reading sensor 11 is accommodated in each of the reading units 61 and 62. In addition, an inclination detection sensor 113 capable of detecting the inclination of the reading sensor, which will be described later, is attached to the reading sensor 11. The reading units 61 and 62 are each provided with a color reference member 17.

  The image reading apparatus 1 includes an upper frame 81 that can rotate around a rotation shaft 81a, and a lower frame 82 that pivotally supports the rotation shaft 81a. A document D is placed between the upper frame 81 and the lower frame 82. The document D is transported by being sandwiched. The upper frame 81 can be manually rotated (opened / closed) to remove the document D staying in the apparatus when a paper jam or the like of the conveyed document D occurs.

  The upper frame 81 accommodates the feeding roller 3, the registration roller 5, the reading unit 61, and the conveyance roller 7, and the lower frame 82 accommodates the separation roller 4, the registration roller 5, the reading unit 62, and the conveyance roller 7. . A portion (not shown) that supports the rotating shaft 81a is configured integrally with the lower frame 82, and extends to both side surfaces (front and back in the figure) so as to sandwich the upper frame 81.

  The drive unit 10 is housed in a portion that supports the rotation shaft 81a in the lower frame 82, and includes a drive mechanism and a drive motor for driving the reading sensor 11 housed in the reading units 61 and 62, respectively. The reading sensor 11 accommodated in the reading units 61 and 62 is moved to the original reading position or the reading position of the color reference member 17 by the driving unit 10.

  Next, a series of operations at the time of image reading of the document D in the image reading apparatus 1 will be described.

  First, the reading sensor 11 accommodated in the reading units 61 and 62 is moved to the reading position of the color reference member 17 by the driving unit 10, and the inclination of the reading sensor 11 is detected by the inclination detection sensor 113.

  Thereafter, the color sensor 17 is read by the reading sensor 11, and shading correction data is generated and recorded based on the output signal and the detection angle obtained by the reading. After recording, the reading sensor 11 is moved to the document reading position, and the document D is taken into the apparatus by the pickup roller 2 and the feeding roller 3 and separated one by one by the separation roller 4.

  The document D is nipped and conveyed by the pair of registration rollers 5 and the pair of conveyance rollers 7, and the front and back images are read in the main scanning direction (document conveyance) by the reading sensors 11 accommodated in the reading units 61 and 62, respectively. Scanning in a direction orthogonal to the direction) is repeated.

  At the time of document reading, the image information generated from the output signal of the reading sensor 11 of the reading units 61 and 62 is corrected with reference to the recorded shading correction data.

  After the original is read, the original D is discharged outside the apparatus while being nipped and conveyed by the pair of conveying rollers 7. The generation and recording of the shading correction data may be performed only once before reading one batch of the original.

  Next, the configuration of the reading sensor 11 will be described with reference to FIG. FIG. 2A is a side view schematically showing the configuration of the reading sensor 11.

  The reading sensor 11 is housed in each of the reading units 61 and 62, and the reading position can be moved between the original reading position and the reading position (position in the arrow b direction) of the color reference member 17 by the driving unit 10. .

  Before reading the document D, the image reading apparatus 1 moves the reading sensor 11 in the direction of arrow b, and reads the surface (white reference surface) of the color reference member 17 that faces the contact glass 15. Shading correction data is generated from the output signal obtained by reading the color reference member 17 and recorded in the memory. Thereafter, the reading sensor 11 is moved to the document reading position, the image information of the document D conveyed in the arrow direction a is read, and the read image information is corrected with reference to the shading correction data recorded earlier. Here, the color reference member 17 is the white reference, but other colors may be set.

  Here, when the reading sensor 11 is moved as shown in FIG. 2B, for example, the reading sensor 11 may be inclined due to vibration of movement. When the color reference member 17 is read with the reading sensor 11 tilted, the incident angle of the light source built in the reading sensor 11 changes. That is, when the incident angle of the light source changes, the amount of light incident on the reading sensor 11 changes, so that shading correction data that is different from the original is generated as it is, and unevenness in density tends to occur in the read image.

  Therefore, in this embodiment, the inclination of the reading sensor 11 caused by moving vibration or the like is detected by the inclination detection sensor 113, and shading correction data is generated (corrected) from the detected angle and the read image information. It is possible to minimize the influence on the shading correction due to the inclination of.

  The inclination detection sensor 113 is attached to the side surface of the reading sensor 11 in the present embodiment, for example. However, the inclination detection sensor 113 is not limited to this, and is in a position that does not interfere with reading of the document D or the color reference member 17. What is necessary is just to attach somewhere in the sensor 11 main body.

  Note that the tilt detection sensor 113 is erroneously determined as the tilt of the reading sensor 11 if the image reading apparatus 1 is placed in a tilted state. Therefore, the inclination angle of the reading sensor 11 when the image reading apparatus 1 is placed on a flat place is recorded in the nonvolatile memory as an initial value (for example, at the time of process inspection at the time of shipment). Hereinafter, the initial value of the tilt angle recorded in the nonvolatile memory is referred to as “tilt angle A”.

The inclination angle X of the reading sensor 11 after turning on the power of the image reading apparatus 1 is compared with the inclination angle A which is an initial value, and the difference between the inclination angle X and the inclination angle A is an arbitrarily determined threshold value α. If it is larger or the same, it is determined that the inclination of the reading sensor 11 or the image reading apparatus 1 is large, and the abnormality of the inclination is notified to the user.

  Next, a schematic electrical configuration of the image reading apparatus 1 in FIG. 1 will be described with reference to FIG. In FIG. 3, reference numeral 11 denotes a reading sensor accommodated in each of the reading units 61 and 62. The reading sensor 11 includes a light source 111 for illuminating the original, a lot lens array (not shown) that collects light reflected from the original, and a line image sensor (not shown) that reads an image of the original from the collected light. And.

  Reference numeral 113 denotes an inclination detection sensor that is attached to a flat portion of the reading sensor 11 and detects the inclination of the reading sensor 11. The tilt detection sensor 113 may be any sensor that can detect tilt, such as an acceleration sensor or a gyro sensor.

  Reference numeral 100 denotes an A / D conversion unit that converts an output signal obtained from the reading sensor 11 into an analog signal such as amplification and black level clamp, and then converts it into a digital signal. Reference numeral 110 denotes an A / D conversion unit that amplifies the output signal of the inclination detection sensor 113 and converts it to a digital signal.

  Reference numeral 101 controls the reading sensor 11, the light source 111, the A / D converter 100, and the like. Further, shading correction data is generated according to the image information converted into a digital signal by the A / D converter 100 and the inclination angle of the reading sensor 11 at the reading position of the color reference member 17.

  The shading correction unit performs shading correction based on the generated shading correction data. In addition, the shading correction unit 101 includes a correction value changing unit 115.

  The correction value changing unit 115 corrects the shading correction data according to the difference between the inclination angle of the reading sensor 11 at the color reference member reading position and the inclination angle of the reading sensor 11 at the document reading position.

  Reference numeral 102 denotes an image storage unit (image memory) for recording image data. Reference numeral 103 denotes an interface unit for connecting to an external host device (personal computer), a network, or the like through the signal line 109.

  A control unit (CPU) 104 controls the image reading apparatus 1. Also, calculation processing such as calculation of the tilt angle of the reading sensor 11 is performed.

  Reference numeral 105 denotes a storage unit (work memory) in which a program for operating the CPU 104 is recorded. A control program for the motor drivers 106 and 107 and a control program for the shading correction unit 101 are written. Also, a control program related to processing of the read image information is written.

  The shading correction unit 101, the CPU 104, the work memory 105, the A / D conversion unit 110, and the correction value change unit 115 are connected to each other via a bus 108. The CPU 104 is configured to be able to access the image memory 102 via the shading correction unit 101.

  Therefore, the CPU 104 can process the image data held in the image memory 102 according to the control program written in the work memory 105.

  Further, the CPU 104 communicates with the A / D conversion unit 110 to calculate an inclination angle based on the inclination of the reading sensor 11 converted into a digital signal, and the calculated inclination angle is sent to the shading correction unit 101 and the correction value change unit 115. Send. Note that an inclination angle calculation unit may be provided separately from the CPU 104, and the inclination angle calculation unit may calculate the inclination angle.

  A conveyance motor 112 conveys the document D. The transport motor 112 is configured to operate by controlling the motor driver 107 from the CPU 104.

  The pulse motor 21 is a component constituting the drive unit 10 and moves the reading sensor 11 between the document reading position and the color reference member reading position for reading the color reference member 17. The pulse motor 21 is configured to operate by controlling the motor driver 106 from the CPU 104.

  Next, the processing flow of this embodiment will be described with reference to the flowcharts of FIGS.

  FIG. 5 is an example of processing of this embodiment. FIG. 4 is a flowchart relating to the tilt angle calculation process. In FIG. 5, after the image reading apparatus 1 is turned on, the inclination angle A, which is the inclination angle (initial value) of the reading sensor 11 recorded in the nonvolatile memory, is read (step S1).

  After reading the tilt angle A, the tilt angle of the reading sensor 11 is calculated (step S2). The process of calculating the tilt angle of the reading sensor 11 is performed according to the flowchart of FIG.

  First, the inclination of the reading sensor 11 is detected by the inclination detection sensor 113 (step S21). The detected tilt output signal is referred to as “slope X”. The inclination X is converted into a digital signal by the A / D converter 110 (step S22). This digital signal is transmitted to the CPU 104 via the bus 108. The CPU 104 calculates an inclination angle from the transmitted digital signal (step S23). The tilt angle calculated from this digital signal is referred to as “tilt angle X”.

  After calculating the tilt angle X, the tilt angle A read from the nonvolatile memory is compared with the tilt angle X, and it is determined whether the difference when compared is greater than or equal to the threshold value α. (Step S3). The determination threshold value α may be arbitrarily determined.

  For example, if the threshold value α is inclined more than an angle that affects the reading of the color reference member or the original, it is determined that an abnormal inclination occurs, and the difference between the inclination angle X and the inclination angle A is determined. Gives an error if the threshold is exceeded. Note that the CPU 104 performs comparison and determination of the tilt angle. Further, the reading timing of the tilt angle A may be after the tilt angle X is calculated.

  As a result of the determination, if the difference between the inclination angle X and the inclination angle A is greater than or equal to the threshold value α (step S3: Yes), the image reading apparatus 1 or the reading sensor 11 is abnormal. If there is an inclination, an error is displayed on the PC screen via the interface unit 103 to prompt the user to check (step S12).

  Alternatively, warning means may be provided in the image reading apparatus 1 in advance, and the user may be notified of the error using the warning means. For example, a beep sound may be emitted or an LED (not shown) may be blinked.

  After the user responds to the error display or warning, the process is performed again from S1. If the read timing of the tilt angle A is after the calculation of the tilt angle X, the process may be started from S2.

  If the difference between the inclination angle X and the inclination angle A is smaller than the threshold value α as a result of the determination in S3 (step S3: No), the reading sensor 11 is moved to the reading position of the color reference member 17. (Step S4).

  After the reading sensor 11 has moved to the reading position of the color reference member 17, the inclination angle of the reading sensor 11 at the position of the color reference member 17 is calculated (step S5). The calculation of the tilt angle is performed according to the flowchart of FIG. 4, and the calculated tilt angle is referred to as “tilt angle Y”.

  After calculating the tilt angle Y, the reading sensor 11 starts reading the color reference member 17 (step S6).

  After the reading of the color reference member 17, the shading correction data is generated according to the image information read by the color reference member 17 and the inclination angle Y (step S7). By generating shading correction data according to the tilt angle Y of the reading sensor 11, shading correction data in which the influence of the tilt angle Y is suppressed can be generated.

  After generating the shading correction data, the reading sensor 11 is moved to the document reading position (step S8). The generation of shading correction data may be performed while the reading sensor 11 is moving.

  After the reading sensor 11 moves to the document reading position, the inclination angle of the reading sensor 11 is calculated (step S9). The tilt angle is calculated according to the flow chart of FIG. 4, and the calculated tilt angle is referred to as “tilt angle Z”.

  After calculating the tilt angle Z, it is determined by comparing whether the tilt angle Z and the tilt angle Y are the same tilt angle (step S10). The comparison and determination are performed by the CPU 104, and it is determined whether or not the correction value changing unit 115 performs correction of the shading correction data generated in S6 based on the determination result. If the tilt angle Z is larger than the correction limit of the shading correction data, an error is displayed on the PC screen as in S12 to prompt the user to check.

  As a result of the determination, if the tilt angle Z is not the same as the tilt angle Y (step S10: No), the correction value changing unit 115 corrects the shading correction data generated in S6 based on the tilt angle Z (step S11).

  Here, a method for correcting shading correction data by the correction value changing unit 115 will be described. First, the difference between the tilt angle Y and the tilt angle Z is calculated. That is, the inclination angle of the reading sensor 11 that occurs when the document reading position is moved is obtained. A correction value x corresponding to the difference in tilt angle is calculated according to the equation (1) to correct the shading correction data.

  Shading correction data × correction value x = corrected shading correction data (1)

  The correction value x is determined in advance as shown in FIG. 7 and recorded in the nonvolatile memory. When correcting the shading correction data, the correction value x is read from the non-volatile memory, the calculation of equation (1) is performed, and the correction is performed.

  For example, the inclination angle Y of the reading sensor 11 at the color reference member position is 0 °. The inclination angle Z of the reading sensor 11 at the document reading position is 1 °. In this case, the difference in tilt angle is 1 °. The correction value x (correction value x = 1.01 from FIG. 7) corresponding to the difference in the tilt angle is read from the nonvolatile memory, calculated according to the equation (1), and the shading correction data is corrected. The shading correction data is corrected by predetermining an angle at which the reading sensor 11 is inclined and a correction coefficient corresponding to the angle, and a correction coefficient determined in advance with respect to the angle at which the reading sensor 11 is actually inclined. May be applied.

  As a result of the determination in S10, when the tilt angle Z is the same as the tilt angle Y (step S9: Yes), reading of the document is started without correcting the shading correction data.

  In addition, when the shading correction data is generated again after starting the document reading and before starting the document reading, the processing may be performed from S4.

  Next, the flow of processing for generating shading correction data according to another method will be described with reference to FIG.

  In the case of the processing flow of FIG. 6, a tilting unit capable of tilting the reading sensor 11 in the image reading apparatus 1 is provided in advance. The tilting unit is configured to tilt the reading sensor 11 at several tilt angles.

  The process flow from S30 to S33 in FIG. 6 is the same as the process flow from S1 to S4 in the flowchart of FIG.

  After the reading sensor 11 has moved to the reading position of the color reference member 17, the reading sensor 11 is tilted by one step by a previously provided tilting means (step S34).

  After tilting the reading sensor 11, the tilt angle of the reading sensor 11 is calculated (step S35). The tilt angle is calculated according to the flowchart of FIG. 4 and the calculated tilt angle is referred to as “tilt angle Y1”.

  After calculating the inclination angle Y1, the reading sensor 11 starts reading the color reference member 17 (step S36).

  After the reading of the color reference member 17 is completed, shading correction data is generated (step S37). After the shading correction data is generated, the shading correction data is recorded in the nonvolatile memory. It should be noted that information on the tilt angle Y1 is added and recorded together with the shading correction data.

  After the generation and recording of the shading correction data is completed, S34 to S38 are repeated a specified number of times (step S38: No). The specified number of times is set at least twice.

  When the reading sensor 11 is tilted again, it is tilted at a tilt angle different from the previous one, and shading correction data at the tilt angle is generated. After the generation, it is recorded in the nonvolatile memory together with the shading correction data and the information of the tilt angle at that time.

  Each time the reading sensor 11 is tilted by one step, the tilt angles become tilt angles Y2, Y3, Y4,... Yn. That is, in the second S34 to S37, shading correction data at the tilt angle Y2 is generated and recorded in the nonvolatile memory together with the information on the tilt angle Y2.

  When S34 to S37 are repeated the specified number of times (step S38: Yes), the reading sensor 11 is returned to the state before the reading sensor 11 is tilted by the tilting means (step S39). For example, if the state before the tilting means tilts the reading sensor is 0 °, the reading sensor 11 is returned to an angle of 0 °.

  After returning the inclination of the reading sensor 11, the reading sensor 11 is moved to the original reading position (step S40).

  After the movement of the reading sensor 11, an inclination angle of the reading sensor 11 at the document reading position is calculated (step S41). The tilt angle is calculated according to the flow chart of FIG. 4, and the calculated tilt angle is referred to as “tilt angle Z”.

  After the inclination angle Z is calculated, the shading correction data having an inclination angle that coincides with or close to the inclination angle Z is read from the nonvolatile memory and selected (step S42). The selected shading correction data is used as shading correction data for the image reading apparatus 1. If the tilt angle Z is larger than the tilt angle threshold at the document reading position, it can be predicted that an abnormality has occurred in the reading sensor 11 when moving to the document reading position. Therefore, as in S43, an error is displayed on the PC screen to urge the user to check.

  Since the shading correction data for each tilt angle is recorded in the nonvolatile memory, the process of tilting the reading sensor 11 by the tilting means and generating the shading correction data may not be performed every time after the power is turned on.

  In the case of the above configuration, the present invention can also be applied to a flatbed image reading apparatus. Since the flatbed image reading apparatus reads the document while moving the reading sensor 11, the reading sensor 11 may be tilted even while the document is being read. Therefore, if the original is read while the reading sensor 11 is tilted, it causes image unevenness.

  Therefore, the inclination detection sensor 113 always detects the inclination of the reading sensor 11 during reading of the document, and calculates the inclination angle. When the reading sensor 11 reaches a certain tilt angle during reading of the document, the position (pixel) and tilt angle at which the reading sensor 11 is tilted are recorded.

  After the reading of the document is completed, the image information at the position where the reading sensor 11 is tilted is corrected using the shading correction data corresponding to the tilt angle of the reading sensor 11. By doing so, it can also be applied to a flat bed type image reading apparatus.

  For example, it is assumed that the reading sensor 11 is inclined by 2 ° during document reading (a position of a certain pixel). After the reading of the document, correction is performed using “data for shading correction when the reading sensor 11 is tilted to 2 °” in which image information (pixels) at a position where the reading sensor 11 is tilted by 2 ° is recorded in advance. To do.

  In the above embodiment, an image reading apparatus capable of reading both sides of a document has been described. Needless to say, the present invention can be applied to an image reading apparatus for single-sided reading.

a conveying direction b moving direction of the reading sensor 11 D document 1 image reading device 2 pickup roller 3 feeding roller 4 separation roller 5 registration roller 7 conveying roller 10 driving unit 11 reading sensor 15 contact glass 17 color reference member 21 pulse motor 61 reading Unit 62 Reading unit 81 Upper frame 81a Rotating shaft 82 Lower frame 100 A / D conversion unit 101 Shading correction unit 102 Image memory 103 Interface unit 104 CPU
105 Work Memory 106 Motor Driver 107 Motor Driver 108 Bus 109 Signal Sensor 110 A / D Converter 111 Light Source 112 Carrying Motor 113 Inclination Detection Sensor 115 Correction Value Changing Unit

Claims (5)

An image reading apparatus including a reading unit that reads a document at a document reading position,
A color reference member which is at a position different from the original reading position and for which the reading means performs shading correction;
Moving means for respectively moving the reading means to the original reading position and the reading position of the color reference member;
An inclination detection sensor for detecting an inclination of an optical axis of the reading unit with respect to a normal direction of the original or the color reference member ;
The image data of the document read by the document reading position A shading correction data for the shading correction by the reading means, to read the color reference member by said reading means in the reading position of the color reference member And a data acquisition unit for acquiring the shading correction data,
Based on the difference between the inclination of the optical axis of the reading means at the original reading position detected by the inclination detection sensor and the inclination of the optical axis of the reading means at the reading position of the color reference member detected by the inclination detection sensor. an auxiliary Seite stage for correcting the shading correction data Te,
An image reading apparatus comprising: An image reading apparatus that reads an image of a document while conveying the document,
Reading means for reading an image of a document at a document reading position;
A white color reference member that is at a position different from the original reading position and for which the reading means performs shading correction;
A reading unit having a moving mechanism for moving the reading means to the original reading position and the reading position of the color reference member;
Moving means for moving the reading means to the original reading position and the reading position of the color reference member by moving the moving mechanism of the reading unit from the outside of the reading unit;
Is attached to the reading means, an inclination of the optical axis of said reading means with respect to the normal direction of the document or the color reference member, the inclination of the optical axis of said reading means in the document reading position, the color An inclination detection sensor capable of detecting the inclination of the optical axis of the reading means at the reading position of the reference member;
Based on the image information obtained by reading the color reference member by the reading unit at the reading position of the color reference member , and the inclination of the optical axis of the reading unit at the reading position of the color reference member detected by the inclination detection sensor. A shading correction unit that generates shading correction data and performs shading correction on the image data of the document read at the document reading position by the reading unit using the shading correction data ;
The inclination of the optical axis of said reading means in the document reading position, on the basis of the difference between the inclination of the optical axis of said reading means in the reading position of the color reference member, complement Seite stage for correcting the shading correction data When,
An image reading apparatus comprising: The accessory Seite stage, the shading correction data, based on the difference between the inclination of the optical axis of said reading means in inclination and the original reading position of the optical axis of said reading means in the reading position of the color reference member the image reading apparatus according to claim 1 or 2, characterized in that to correct. An image reading apparatus including a reading unit that reads a document at a document reading position,
A color reference member which is at a position different from the original reading position and for which the reading means performs shading correction;
Moving means for respectively moving the reading means to the original reading position and the reading position of the color reference member;
An inclination detection sensor for detecting an inclination of an optical axis of the reading unit with respect to a normal direction of the original or the color reference member;
Shading correction data for shading correction of image data of the original read at the original reading position by the reading means, wherein the reading means reads the color reference member at the color reference member reading position. And a data acquisition unit for acquiring the shading correction data,
Inclination means capable of changing the inclination of the optical axis of the reading means at the reading position of the color reference member, the reading means is inclined by the inclination means, and shading correction data at the inclination is obtained by the data acquisition unit. acquired, images reader, characterized in that the shading correction data of said reading means the shading correction data for matching or close the inclination to the inclination of the optical axis of said reading means in the document reading position. The inclination of the optical axis of the reading means is an initial value, and after the power is turned on, the inclination detection sensor detects the inclination of the optical axis of the reading means at the original reading position, and the initial value and the original reading position are detected. Is compared with the inclination of the optical axis of the reading means, and if the difference at the time of comparison is larger than an arbitrary threshold value, it is determined that the inclination is abnormal, and an error display or warning means is used for the display means. the image reading apparatus according to claim 1 or 2, characterized in that to inform the abnormality of the inclination of the optical axis of said reading means.

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