JP2012160841A - Image reading device and program therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct read data irrespective of failure of a reference member.SOLUTION: A multifunction peripheral 1 comprises a reading unit 60 for reading a document, and a white tape 80 arranged facing the reading unit 60. The multifunction peripheral 1 acquires correction data for shading correction from a reading result obtained by the reading unit 60 reading the white tape 80. Also, correction data for shading correction is acquired from a reading result obtained by the reading unit 60 reading a margin portion of a document conveyed in an ADF 40. The multifunction peripheral 1 determines whether or not the reading result obtained by reading the white tape 80 has abnormality, and when it is determined to have no abnormality, performs shading correction on image data obtained by the reading unit 60 reading the document using the correction data acquired using the white tape 80. Then, when it is determined to have abnormality, shading correction on the image data is performed using the correction data acquired using the margin portion of the document.

Description

  The present invention relates to a technique for correcting read data regardless of a defect of a reference member used for obtaining a white reference value or the like for shading correction.

  2. Description of the Related Art Conventionally, in an image reading apparatus such as a scanner, a technique is known in which a reference member used to acquire a white reference value for shading correction of scanned read data is included (for example, Patent Document 1). In this image reading apparatus, a white reference value or the like is acquired using a reference member prior to reading a document, and various corrections such as shading correction are performed on the read data using the acquired white reference value or the like. In addition, a technique for acquiring a white reference value or the like using the document itself is also known (for example, Patent Document 2). In this technique, before reading the central portion of the document on which an image or the like is formed, the white reference value or the like is acquired using the margin portion of the document existing around the central portion, and the acquired white reference value or the like is used. Then, various corrections such as shading correction are performed on the read data.

JP 2010-219773 A JP 2010-4110 A

  Since the reference member is used to acquire a white reference value or the like, it is preferable that the reference member is placed in a place where dirt in the apparatus is difficult to adhere. However, for example, in a reading unit disposed in an automatic document feeder (ADF), a corresponding reference member may be disposed in a conveyance path through which the document is conveyed, and the reference member becomes dirty when the document passes. Can not be suppressed. If dirt is attached to the reference member, various corrections cannot be made to the read data with high accuracy unless the dirt is removed by the user or the like.

  In such a reading unit, it seems to be effective to acquire a white reference value or the like using a document without using a reference member as in the second prior art. However, in general, the reference member is often specially processed so that the white reference value or the like can be accurately acquired. The white reference value or the like acquired using the manuscript is the white reference value acquired using the reference member or the like. The accuracy is worse than the reference value. Therefore, if the reference member is not used as in the second prior art, the accuracy of the read data is deteriorated as compared with the case where the reference member is used as in the first prior art. I can't avoid that.

  The present specification discloses a technique for correcting read data regardless of a defect of a reference member.

  An image reading apparatus disclosed in this specification includes a reading unit that reads a document, a reference member that is disposed to face the reading unit, and a shading correction based on a first reading result that the reading unit reads the reference member. A first acquisition unit that acquires first correction data for use, a second acquisition unit that acquires second correction data for shading correction from a second reading result obtained by the reading unit reading a blank portion of the document, When the determination unit determines whether there is an abnormality in the first reading result and the determination unit determines that there is no abnormality in the first reading result, the reading unit uses the first correction data. The reading data obtained by reading the original is subjected to shading correction, and when the determination unit determines that there is an abnormality in the first reading result, the reading data is subjected to shading correction using the second correction data. It includes a correction unit, the.

  In the above image reading apparatus, the reference member may be arranged so as not to move relative to the reading unit.

  Further, the image reading apparatus has a reference reading result, and the determination unit exceeds the first reading result when the first reading result is different from the reference reading result exceeding a predetermined degree of change. It may be configured to determine that the reading result is abnormal.

  In the image reading apparatus, the reading unit repeatedly acquires the first reading result, and the determination unit reads the first reading result acquired last time as the reference reading of the first reading result acquired this time. It is good also as a structure used as a result.

  In the image reading apparatus, when the determination unit determines that there is an abnormality in the first reading result, when the reading unit reads a plurality of documents, the reading unit reads the first of each document. While reading the two reading results, the second acquisition unit acquires each second correction data from each second reading result, and the second acquisition unit acquires the second correction data acquired this time before that The average correction data averaged with the second correction data may be calculated, and the correction unit may be configured to perform shading correction on the read data using the average correction data.

  In the image reading apparatus, the reading unit includes a plurality of color light sources, and each light source emits light to detect a reading result of each color, and further, the reading unit reads each color by reading the reference member. It is good also as a structure provided with the light quantity adjustment part which adjusts the light quantity of the said light source so that the maximum value of a result may correspond in all the colors.

  The present invention can be realized in various modes such as a computer program for realizing the functions of these devices, a recording medium on which the program is recorded, in addition to the image reading devices described above.

  In the image reading apparatus disclosed in this specification, when a defect occurs in the reference member and it is determined that there is an abnormality in the first reading result, the first correction data obtained from the reference member is used instead of the first correction data. The read data is subjected to shading correction using the second correction data obtained from the margin. For this reason, when there is no abnormality in the first reading result, the reading data can be subjected to shading correction with high accuracy using the reference member. In addition, when there is an abnormality in the first reading result, it is possible to ensure a certain correction accuracy by performing shading correction on the read data using the margin portion of the document. In this case, it is possible to suppress the deterioration of the accuracy of the shading correction compared to the case where the read data is subjected to the shading correction using the first correction data obtained from the defective reference member, and the read data is accurately obtained. On the other hand, shading correction can be performed.

The figure which shows the state which raised the document cover of the multi-function device 1 Schematic sectional view of the image reading device 3 of the multifunction device 1 Block diagram schematically showing the electrical configuration of the multifunction machine 1 A diagram schematically showing a document read by the multifunction machine 1 6 is a flowchart illustrating a reading process according to the first embodiment. 5 is a flowchart illustrating AFE input range adjustment processing according to the first embodiment. The flowchart which shows the RGB color light quantity adjustment process of Embodiment 1. The graph which shows the reading result after AFE input range adjustment processing The graph which shows the reading result after RGB color light quantity adjustment processing The graph which shows the reading result after a RGB color shading data calculation process 7 is a flowchart illustrating reading processing according to the second embodiment. A flowchart showing a reading process according to the third embodiment. The graph which shows the problem of Embodiment 1, 2

<Embodiment 1>
The first embodiment will be described with reference to FIGS.

1. FIG. 1 is a perspective view showing an external appearance of a multi-function machine 1 which is an example of an image forming apparatus according to the present invention. FIG. 1 shows an external view of the multi-function machine 1 in an open state with a document cover 48 raised. The multifunction device 1 is a multi-function peripheral device having a printer function, a scanner function, a copy function, a facsimile function, and the like. FIG. 2 is a cross-sectional view of the image reading apparatus 3 in the closed posture with the document cover 48 lowered.

  As shown in FIG. 1, the multifunction machine 1 includes an image reading device 3 for reading a document above a main body 2. The image reading device 3 includes a reading unit 30, an automatic document feeder (ADF) 40, a document placing unit 50, and the like which will be described later.

  The document placing unit 50 includes a frame 51, a first platen glass 52 made of a transparent glass plate, a second platen glass 53, and an intermediate frame 54 disposed between these glasses 52 and 53. The document placement section 50 is covered with a document cover 48 so as to be opened and closed.

  The document cover 48 can be rotated between a closed posture that covers the document placement portion 50 and an open posture that opens the document placement portion 50, and the rear side of the main body 2 of the multifunction machine 1 (the operation portion 11, the display portion). The side on which 12 etc. are provided is connected to the front side). An ADF 40 is provided on the document cover 48.

  As shown in FIG. 2, the ADF 40 includes an ADF cover 41, a document tray 42, pressing members 43 and 44, various rollers 46, a paper discharge tray 47, a third platen glass 55 made of a transparent glass plate, a reading unit 60, and Document sensors 70 to 72 and the like are included.

  The ADF 40 is provided with a transport path 45 that is a path through which the document is transported from the document tray 42 to the paper discharge tray 47 by the roller 46 and the like, and the reading unit 30 and the reading unit 60 ( An example of a reading unit) is arranged.

  The reading unit 30 is disposed in the main body unit 2 and is supported so as to be movable in a direction along the glasses 52 and 53 indicated by arrows 84 in FIG. The reading unit 30 moves in a direction along the glasses 52 and 53, and reads a document placed on the first platen glass 52. 2 moves to a reading position L below the second platen glass 53 indicated by a solid line in FIG. At this time, the reading unit 30 is disposed on the downstream side of the reading unit 60 in the conveyance path 45 (that is, the discharge tray 47 side), and the document conveyed on the conveyance path 45 passes over the second platen glass 53. When reading the original. The pressing member 44 is arranged to face the reading unit 30 in a state where the pressing member 44 is moved to the reading position L via the second platen glass 53, and a document passing over the second platen glass 53 does not float from the second platen glass 53. As described above, the original is pressed against the second platen glass 53. In the following description, it is assumed that the state and operation of the reading unit 30 at the reading position L are described unless otherwise specified.

  A reference white plate 81 is disposed at the lower part of the intermediate frame 54 so that the surface thereof is at the same height as the lower surfaces of the glasses 52 and 53. The reading unit 30 uses the reference white plate 81 to perform shading correction, color tone correction, and the like. Detecting reading results necessary for various corrections. When detecting the reading result, the reading unit 30 moves to a position where the reference white plate 81 is included in the reading region Q of the reading unit 30 and reads the reference white plate 81 corresponding to the reading region Q. At this time, the portion where the reading unit 30 reads the reference white plate 81 may be set to any portion of the surface of the reference white plate 81 facing the reading unit 30.

  The reading unit 60 is disposed on the upstream side of the reading unit 30 in the conveyance path 45 (that is, the document tray 42 side), and is supported so as not to move with respect to the ADF 40. The reading unit 60 reads the original when the original conveyed on the conveyance path 45 passes over the third platen glass 55. The pressing member 43 is disposed so as to face the reading unit 60 with the third platen glass 55 interposed therebetween, and is supported so as not to move in the document transport direction indicated by an arrow 83 in FIG. That is, the pressing member 43 is supported so as not to move relative to the reading unit 60 in the document transport direction. The pressing member 43 presses the document against the third platen glass 55 so that the document passing over the third platen glass 55 does not float from the third platen glass 55.

  A white tape (an example of a reference member) 80 is affixed to the surface of the pressing member 43 facing the reading unit 60, and the reading unit 60 uses the white tape 80 to read the reading results necessary for various corrections described later. Is detected. When the reading unit 30 detects the reading result, the reading unit 30 reads the portion of the white tape 80 corresponding to the reading region P of the reading unit 60. The pressing member 43 and the reading unit 60 are supported so as not to be relatively movable in the document transport direction. Therefore, the portion where the reading unit 60 reads the white tape 80 is limited to a specific position on the surface of the white tape 80 facing the reading unit 60.

  Further, the reading unit 60 detects reading results necessary for various corrections to be described later using a document conveyed on the conveyance path 45. When detecting the reading result, the reading unit 30 reads the margin portion Y1 when the margin portion Y1 of the document conveyed on the conveyance path 45 reaches the reading region P of the reading unit 60. Here, the “margin” means an area where no image or the like of the document is formed as shown in FIG. 4, and specifically, about several millimeters inside the outer periphery in the document conveyance direction indicated by an arrow 83. Means the area. As shown in FIG. 4, the reading portion Y2 when the reading units 30 and 60 read the document is set inside the margin portion Y1 in the document transport direction.

  The document sensor 70 is disposed adjacent to the document tray 42 and is supported so as to be rotatable around a shaft 70 </ b> A provided on the lower side of the document tray 42. The document sensor 70 is connected to a central processing unit 20 described later, and the central processing unit 20 detects that a document is placed on the document tray 42 based on a signal output from the document sensor 70.

  The document sensor 71 is disposed on the upstream side of the reading unit 60 in the conveyance path 45 and close to the reading unit 60. Further, the document sensor 72 is disposed in the conveyance path 45 on the downstream side of the reading unit 60 and on the upstream side of the reading unit 30 in the vicinity of the reading unit 30.

  Document sensors 71 and 72 are connected to the central processing unit 20. Based on the signal output from the document sensor 71, the central processing unit 20 detects that the document conveyed on the conveyance path 45 has approached the reading unit 60. Further, the central processing unit 20 detects that the document conveyed on the conveyance path 45 has approached the reading unit 30 based on a signal output from the document sensor 72.

  In the ADF 40, when the document sensor 70 detects that the document is placed on the document tray 42, the roller 46 is driven to convey the documents placed on the document tray 42 to the conveyance path 45 one by one. The document transported to the transport path 45 passes through the third platen glass 55 and the second platen glass 53 positioned on the transport path 45 and is discharged to the paper discharge tray 47.

  At this time, the reading unit 60 detects that the document has reached the reading unit 60 via the document sensor 71, detects the second reading result from the document passing over the third platen glass 55, and Read the side. The reading unit 30 detects that the document has reached the reading unit 30 via the document sensor 72, and reads the outer surface of the document passing over the second platen glass 53.

Next, the structure of the reading units 30 and 60 will be described. The reading units 30 and 60 have the same structure, and the description will be made using the reading unit 60 here, and a duplicate description will be omitted.
The reading unit 60 reads a document passing over the third platen glass 55 by a so-called CIS method using a CIS (Contact Image Sensor). The reading unit 60 includes a linear image sensor 63 in which a plurality of light receiving elements are linearly arranged in a direction perpendicular to the paper surface of FIG. A rod lens array 62 that forms an image of each reflected light on each light receiving element of the linear image sensor 63, and a carriage 64 on which these are mounted. Unlike the carriage 34 of the reading unit 30, the carriage 64 of the reading unit 60 reads a document at a fixed position without being conveyed.
Further, the structures of the reading units 30 and 60 are not necessarily the same structure. Either the reading unit 30 or the reading unit 60 may be a CIS and the other may be a CCD.

  The light source 61 includes a red LED 61R that emits red light, a green LED 61G that emits green light, and a blue LED 61B that emits blue light, and irradiates the reading region P facing the linear image sensor 63 with light. . The light source 61 irradiates the reading region P with light of each color by separately irradiating these three colors of LEDs. The linear image sensor 63 detects the reflected light that is reflected on the reading region P and imaged on each light receiving element. The reading area P includes a conveyance path 45, and the linear image sensor 63 is configured so that a document conveyed on the conveyance path 45 passes through the third platen glass 55 via the transparent third platen glass 55. In addition, the reflected light reflected from the surface of the document in contact with the third platen glass 55 is detected.

  Each light receiving element detects the intensity of reflected light reflected from the unit reading area obtained by dividing the reading area P by the number of light receiving elements as the magnitude of the voltage value. Each light receiving element executes this detection as many times as the number of detections corresponding to the situation. As a result, the linear image sensor 63 detects unit data of the number of light receiving elements in a direction orthogonal to the document transport direction, and detects unit data of the number of detections in the document transport direction. The linear image sensor 63 detects a reading result and image data (an example of reading data) including these unit data detected by each light receiving element. The reading unit 60 is not limited to the CIS method, but may be a so-called CCD method using a CCD (Charge Coupled Device) image sensor.

  Further, on the front side of the multifunction device 1, an operation unit 11 that includes various buttons and receives an operation command from a user, and a display unit 12 that includes a liquid crystal display that displays the state of the multifunction device 1 are provided.

2. FIG. 3 is a block diagram schematically showing the electrical configuration of the multifunction device 1. As shown in FIG. 3, the multifunction machine 1 includes an ASIC (application specific integrated circuit) 10 that controls each unit of the multifunction machine 1. The ASIC 10 includes a central processing unit (hereinafter referred to as “CPU”) 20, a ROM 24, a RAM (an example of a storage unit) 25, a device control unit 26, and image processing units 27 and 28, which include an operation unit 11, a display unit 12, The reading units 30 and 60, analog front ends (hereinafter referred to as “AFE”) 35 and 65, a motor M for driving a roller 46 (see FIG. 2), a drive circuit 16, document sensors 70 to 72, and the like are connected.

  Various programs for controlling the operation of the multifunction device 1 are stored in the ROM 24, and the CPU 20 acquires an acquisition unit (an example of a first acquisition unit and a second acquisition unit) 21 according to the program read from the ROM 24, It functions as the determination unit 22, the correction unit 23, and the like, and controls each unit.

  The device control unit 26 is connected to the reading units 30 and 60, and based on instructions from the CPU 20, the LEDs of the light sources 31 and 61 are turned on, the output voltages of the light sources 31 and 61, and the linear image sensors 33 and 63. A signal for controlling the reading result and the detection of image data is transmitted to the reading units 30 and 60. The reading result and the image data which are analog data detected by the reading units 30 and 60 are transmitted to the AFEs 35 and 65.

  The device control unit 26 is also connected to the AFEs 35 and 65, and transmits a signal for controlling the input range of the AFEs 35 and 65 to the AFEs 35 and 65 based on an instruction from the CPU 20. The AFEs 35 and 65 are configured such that although the input range width is determined in advance, the upper limit value or the lower limit value thereof can be adjusted. In the AFEs 35 and 65, a resolution (here, 256) is set in advance, and a gradation voltage corresponding to each gradation value included in the resolution is set from the input range. When the input range is adjusted based on a command from the CPU 20, the AFEs 35 and 65 determine the gradation voltage, and compare the reading result and image data transmitted from the reading units 30 and 60 with the gradation voltage. The AFEs 35 and 65 convert the read result and the image data into gradation values corresponding to the gradation voltage having the closest value, and transmit the gradation values to the image processing units 27 and 28.

  When the image processing units 27 and 28 receive the reading results converted into gradation values from the AFEs 35 and 65, the image processing units 27 and 28 acquire correction data used for shading correction of the image data from the reading results based on a command from the CPU 20, The correction data is stored in the RAM 25. In addition, when the image processing units 27 and 28 receive image data from the reading units 30 and 60 via the AFEs 35 and 65, the image processing units 27 and 28 perform shading correction based on a command from the CPU 20 and store the image data in the RAM 25.

3. Reading Processing Next, processing in the CPU 20 when reading a document using the reading unit 60 of the ADF 40 will be described with reference to FIGS.

  FIG. 5 shows a flowchart of the present embodiment executed by the CPU 20 according to a predetermined program. The CPU 20 starts processing when a user places a document on the document tray 42 of the multifunction peripheral 1 and inputs a document reading instruction from the reading unit 60 via the operation unit 11 or the inputable display unit 12. . The CPU 20 checks whether or not a document is placed on the document tray 42 using the document sensor 70 (S2). If no document is placed on the document tray 42, the reading process by the ADF 40 is terminated. Then, the process proceeds to a reading process (FB reading) when a document is placed on the glass 52 (S2: NO).

  On the other hand, when a document is placed on the document tray 42 (S2: YES), the CPU 20 starts conveying the document (S4). The CPU 20 drives the roller 46 using the motor M and the drive circuit 16 and conveys the document to the conveyance path 45.

  The CPU 20 first acquires correction data from the white tape 80 until it is confirmed by the document sensor 71 that the margin Y1 at the front end in the document conveyance direction has reached the reading area P of the reading unit 60 after the document conveyance is started. The first acquisition process Z1 is performed. At this time, the CPU 20 functions as the acquisition unit 21. In the first acquisition process Z1, the CPU 20 first executes an AFE input range adjustment process (S6). As shown in FIG. 6, the CPU 20 turns off the light source 61 (S42) and detects the read result K (x) (S44). Here, x means each light receiving element constituting the linear image sensor 63, and when the reading result K (a) is described, it particularly indicates the reading result detected by the light receiving element a.

  The CPU 20 calculates Kmin, which is the minimum value of the detected reading result K (x) (S46), and adjusts the input range of the AFE 65 so that Kmin becomes equal to the lower limit value of the input range of the AFE 65 (see FIG. 8). ). Thereby, the upper limit value of the input range is determined from the width of the input range determined in advance, and each gradation voltage of the AFE 65 is determined.

  Next, the CPU 20 executes an RGB color light amount adjustment process (S8). As shown in FIG. 7, the CPU 20 sets the output voltage of the light source 61 to the initial voltage (S52), turns on the red LED 61R of the light source 61 (S54), and detects the read result R (x) (S56: FIG. 8). The CPU 20 calculates Rmax, which is the maximum value of the read result R (x) (S58), and adjusts the output voltage of the light source 61 so that Rmax is equal to the upper limit value of the input range of the AFE 65 (S60: FIG. 9). reference). Specifically, the output voltage of the light source 61 is adjusted so that the gradation value of Rmax becomes 255 (minimum gradation value: 0) which is the maximum gradation value. The CPU 20 separately performs the RGB color light amount adjustment processing for the red LED 61R, the green LED 61G, and the blue LED 61B, and adjusts the output power independently for each color LED.

  Next, the CPU 20 executes an RGB color monochrome level data reading process (S10). The CPU 20 turns on the red LED 61R of the light source 61 with the output voltage adjusted by the RGB color light amount adjustment processing, and detects the read result R (x) again. Similarly, the green LED 61G and the blue LED 61B are turned on with the output voltage adjusted by the RGB color light amount adjustment processing, and the reading result G (x) and the reading result B (x) are detected again.

  The reading result R (x), the reading result G (x), and the reading result B (x) shown in the following description mean reading results detected again in the RGB color / monochrome level data reading process. In the read result R (x), the read result G (x), and the read result B (x) detected again, the maximum values of all colors coincide with the upper limit value of the input range of the AFE 65 as shown in FIG. . The reading result R (x), the reading result G (x), the reading result B (x), and the reading result K (x) are converted into gradation values by the AFE 65, and the reading gradation Wr (x) and the reading gradation are converted. Wg (x), read gradation Wb (x), and read gradation D (x) are stored in the RAM 25.

Next, the CPU 20 executes RGB color shading data calculation processing (S12). The CPU 20 calculates shading data SDr (x) obtained by dividing 255, which is the maximum gradation value of the AFE 65, by the difference value between the read gradation Wr (x) and the read gradation D (x). Similarly, the CPU 20 calculates the shading data SDg (x) using the reading gradation Wg (x) and the reading gradation D (x), and calculates the reading gradation Wb (x) and the reading gradation D (x). To calculate shading data SDb (x).
SDr (x) = 255 / (Wr (x) -D (x))
SDg (x) = 255 / (Wg (x) -D (x))
SDb (x) = 255 / (Wb (x) -D (x))

  The shading data SDr (x) is correction data used when shading correction is performed on image data acquired with the red LED 61R lit out of the image data acquired by the reading unit 60. As shown in FIG. 10, the reading result R (x) is corrected by shading using the shading data SDr (x), and the corrected reading result R ′ (x) is obtained in all the light receiving elements of the linear image sensor 63. , Correction is made to be equal to the upper limit value of the input range of the AFE 65. Further, the shading correction is performed on the read result K (x) using the shading data SDr (x), so that the corrected read result K ′ (x) is the input range of the AFE 65 in all the light receiving elements of the linear image sensor 63. It is corrected to be equal to the lower limit value of. The same applies to the shading data SDg (x) and the shading data SDb (x), and redundant description is omitted.

  When the CPU 20 completes the first acquisition process Z1, a defect has occurred in the white tape 80 until it is confirmed by the document sensor 71 that the margin Y1 at the front end of the document conveyance direction has reached the reading region P of the reading unit 60. Whether or not (S14). At this time, the CPU 20 functions as the determination unit 22. Here, “problem” means that an abnormality such as dirt or damage has occurred in a portion corresponding to the reading region P of the reading unit 60 of the white tape 80.

  The CPU 20 compares the shading data SD (x) acquired in the current reading process with the shading data SD (x) acquired in the previous reading process, and calculates the difference ΔSD (x) of the shading data SD (x). calculate. Further, the CPU 20 measures an elapsed time from the previous reading process to the current reading process, and sets an allowable range F (x) (an example of the degree of change) based on the elapsed time. The allowable range F (x) is set based on the aging of the light source 61 with respect to the elapsed time from the previous reading process to the current reading process. The CPU 20 compares the difference ΔSD (x) with the allowable range F (x), and determines that no defect has occurred in the white tape 80 when the difference ΔSD (x) is equal to or smaller than the allowable range F (x). (S14: NO), the document sensor 71 confirms whether or not the leading end of the document reading portion Y2 has reached the reading region P of the reading unit 60 (S26).

  On the other hand, if the difference ΔSD (x) is larger than the allowable range F (x), the CPU 20 determines that a defect has occurred in the white tape 80 (S14: YES), and uses the margin portion Y1 of the document. The second acquisition process Z2 for acquiring the corrected data is performed. At this time, the CPU 20 functions as the acquisition unit 21. The CPU 20 waits for the document sensor 71 to allow the margin portion Y1 on the leading end side in the document transport direction to reach the reading region P of the reading unit 60 (S16: NO), and the margin portion Y1 becomes the reading region P of the reading unit 60. (S16: YES), AFE input range adjustment processing (S18), RGB color light amount adjustment processing (S20), RGB color monochrome level data reading processing (S22), and RGB color shading data calculation processing (S24). Execute. These processes are the same as the processes of the same name in the first acquisition process Z1, and a duplicate description is omitted. Thereby, shading data SD (x) using the margin portion of the document is acquired.

  Next, the CPU 20 waits until the reading portion Y2 at the leading end in the document transport direction reaches the reading area P of the reading unit 60 by the document sensor 71 (S26: NO), and the reading portion Y2 reads by the reading unit 60. When the area P is reached (S26: YES), the reading mode is set (S28). If it is determined in S14 that no malfunction has occurred, the CPU 20 adjusts the values to the input range of the AFE 65 and the output voltage of the light source 61 that have been adjusted in the first acquisition process Z1. On the other hand, if it is determined in S14 that a problem has occurred, the CPU 20 adjusts the values to the input range of the AFE 65 and the output voltage of the light source 61 adjusted in the second acquisition process Z2.

Next, the CPU 20 reads the reading portion Y2 of the document using the reading unit 60, and detects the image data I (x) (Ir (x), Ig (x), Ib (x)) (S30). Subsequently, the CPU 20 performs shading correction on the image data I (x) (S32). At this time, the CPU 20 functions as the correction unit 23. If it is determined in S14 that no malfunction has occurred, the CPU 20 uses the shading data SD (x) acquired from the white tape 80 to correct the shading of the image data I (x). On the other hand, if it is determined in S14 that a problem has occurred, the image data I (x) is subjected to shading correction using the shading data SD (x) acquired from the margin Y1 of the document. The corrected image data I ′ (x) is expressed as follows using the shading data SD (x).
I′r (x) = SDr (x) × (Ir (x) −D (x))
I′g (x) = SDg (x) × (Ig (x) −D (x))
I′b (x) = SDb (x) × (Ib (x) −D (x))

  After completing the shading correction (S32) of the image data I (x), the CPU 20 checks whether or not the next document is placed on the document tray 42 using the document sensor 70 (S34). If no document is placed on the document tray 42 (S34: NO), the CPU 20 ends the process. On the other hand, when the next document is placed on the document tray 42 (S34: YES), the CPU 20 returns to S17 and repeats the above processing.

4). Advantages of this embodiment (1) In the multifunction device 1 of this embodiment, a defect occurs in the white tape 80, and the read results R (x), G (x), and B (x) detected from the white tape 80 are displayed. When it is determined that there is an abnormality, instead of the shading data SD (x) obtained from the white tape 80, the shading data SD (x) obtained from the margin Y1 of the document is used to obtain the image data I (x ) For shading correction.

  The reference members such as the white tape 80 and the reference white plate 81 are generally specially processed and are suitable for shading correction of the image data I (x) as compared with the original. However, the reference white plate 81 is disposed inside the main body 2 and does not come into contact with the document, and it is difficult for defects such as dirt to occur, whereas the white tape 80 is disposed to face the reading unit 60. For this reason, there may be a problem that dirt is attached when the document passes. In this case, the image data I (x) is not suitable for shading correction compared to the original.

  In this multifunction device 1, when the white tape 80 is not defective and the reading results R (x), G (x), and B (x) detected from the white tape 80 are not abnormal, the white tape 80 can be used for shading correction of the image data I (x) with high accuracy. If there is a defect in the white tape 80 and the reading results R (x), G (x), and B (x) detected from the white tape 80 are abnormal, the margin portion Y1 of the document is used. By correcting the shading of the image data I (x), a certain correction accuracy can be ensured. In this case, it is possible to suppress a reduction in the accuracy of the shading correction as compared with the case where the shading correction is performed on the image data I (x) using the shading data SD (x) acquired from the white tape 80 in which the problem has occurred. It is possible to perform shading correction on the image data I (x) with high accuracy.

(2) In particular, in the reading unit 60, the pressing member 43 to which the white tape 80 is attached is disposed so as not to move in the document transport direction with respect to the reading unit 60. A structural limitation in which, when a reading position is fixed and a problem occurs at that position, the problem cannot be solved by moving the reading region P of the reading unit 60 along the document conveyance direction. Have

  In the multi-function device 1, when a problem such as dirt is attached to a portion corresponding to the reading region P of the reading unit 60 of the white tape 80, the shading data SD (x) acquired from the white tape 80 is replaced. Since the image data I (x) is subjected to the shading correction using the shading data SD (x) obtained from the margin Y1 of the document, the reading unit 60 having the above structure can also perform the shading correction with high accuracy. .

(3) In the multifunction device 1 of the present embodiment, when determining whether or not a defect has occurred in the white tape 80, the shading data SD (x) obtained from the white tape 80 in the current reading process is used as the previous time. Compared with the shading data SD (x) obtained from the white tape 80 in the reading process, the occurrence of a defect in the white tape 80 is determined. Therefore, it is possible to accurately detect a defect in the white tape 80 that occurs between the timing at which the previous shading data SD (x) is acquired and the timing at which the current shading data SD (x) is acquired.

(4) When comparing the shading data SD (x), the CPU 20 determines the allowable range F (x based on the aging degradation of the light source 61 with respect to the elapsed time from the previous reading process to the current reading process. ) And a difference value between the allowable range F (x) and the shading data SD (x) is compared. Therefore, for example, when the reading results R (x), G (x), and B (x) detected from the white tape 80 have deteriorated beyond the aging deterioration, these reading results R (x) and G (x ) And B (x) are easy to determine.

<Embodiment 2>
A second embodiment will be described with reference to FIG. The present embodiment is different from the first embodiment in that the average shading data HSD (x) is calculated from the shading data SD (x) obtained from the margin portion of the document acquired in the reading process. In the following description, the same description as that of the first embodiment will not be repeated.

1. Reading Process FIG. 11 shows a flowchart of the present embodiment that the CPU 20 executes according to a predetermined program. If it is determined that a defect has occurred in the white tape 80 (S14: YES), the CPU 20 acquires correction data using the margin portion Y1 of the document (S16 to S24).

  Next, the CPU 20 checks whether or not the document currently being read is the first document after the reading process is started (S62). If the document currently being read is the first document (S62: YES), the processing from S26 is executed.

  On the other hand, when the document currently being read is the second and subsequent documents after the reading process is started (S62: NO), average shading data HSD (x) is calculated. The CPU 20 averages the shading data SD (x) obtained from the margin portion of the original document acquired this time and the shading data SD (x) obtained from the margin portion of the original document acquired so far in the reading process. Then, the average shading data HSD (x) is calculated (S64).

  In the present embodiment, when it is determined that a defect has occurred in the white tape 80 (S14: YES), in S32, the CPU 20 determines the first sheet after the original currently being read starts the reading process. In the case of a document, the image data I (x) is subjected to shading correction using the shading data SD (x) obtained from the margin of the first document, and the document currently being read starts the reading process. In the case of the second and subsequent originals, the shading correction is performed on the image data I (x) using the average shading data SD (x).

2. Effects of the present embodiment In the multifunction device 1 of the present embodiment, when the shading correction is performed on the image data I (x) by using the shading data SD (x) obtained from the margin portion of the original, it is obtained from each original. Average shading data HSD (x) obtained by averaging the shading data SD (x) is calculated, and the image data I (x) is subjected to shading correction using the average shading data HSD (x). According to the multi function device 1, it is possible to suppress variations in the shading data SD (x) due to variations in the document, and image data with high accuracy using the shading data SD (x) obtained from the margin of the document. I (x) can be subjected to shading correction.

<Embodiment 3>
Embodiment 3 will be described with reference to FIG. 12 or FIG. In the present embodiment, the read results R (x) and G detected from the white tape 80 are used for the AFE input range adjustment process and the RGB color light amount adjustment process regardless of whether or not a defect occurs in the white tape 80. (X), B (x) is different from the first embodiment in that the process is executed. Different from the first embodiment. In the following description, the same description as that of the first embodiment will not be repeated.

  FIG. 12 shows a flowchart of the present embodiment that the CPU 20 executes according to a predetermined program. When it is determined that a defect has occurred in the white tape 80 (S14: YES), the CPU 20 performs a third acquisition process Z3 for acquiring correction data using the margin portion Y1 of the document. Similar to the second acquisition process Z2, the third acquisition process Z3 includes processes such as an RGB color / monochrome level data reading process (S22) and an RGB color shading data calculation process (S24). On the other hand, unlike the second acquisition process Z2, the third acquisition process Z3 does not include the AFE input range adjustment process (S18) and the RGB color light amount adjustment process (S20).

  In the present embodiment, when the CPU 20 sets the reading mode in S28, the input range and light source of the AFE 65 adjusted in the first acquisition process Z1 regardless of whether or not it is determined in S14 that no problem has occurred. The value is adjusted to 61 output voltage.

2. Effects of the present embodiment In the multi-function device 1 of the present embodiment, regardless of whether or not a defect occurs in the white tape 80, the input range of the AFE 65 and the output voltage of the light source 61 that have been adjusted in the first acquisition process Z <b> 1. And adjust the value. That is, the input range of the AFE 65 and the output voltage of the light source 61 are adjusted based on the result detected using the white tape 80.

  The document may be originally colored, for example, there is a document colored in blue. In this case, when the image data I (x) detected from the white document is corrected using the shading data SD (x) obtained from the margin Y1 of the document, as shown in FIG. The results R ′ (x) and G ′ (x) are corrected so as to be equal to the upper limit value of the input range of the AFE 65 in all the light receiving elements of the linear image sensor 63. On the other hand, the corrected reading result B ′ (x) is not equal to the upper limit value of the input range of the AFE 65 in all the light receiving elements of the linear image sensor 63 due to the influence of the document from which the shading data SD (x) is detected. . Further, an uncolored document may not be white in the first place, and the same problem occurs in this case.

  The correction of the image data I (x) using such shading data SD (x) means that the image data I (x) is obtained using the shading data SD (x) obtained from the white tape 80 in which a defect has occurred. Although the image data I (x) can be more accurately subjected to shading correction than correcting the image, the detected image data I (x) is affected by the original from which the shading data SD (x) is detected, and the same original However, there is a problem that the constant image data I (x) cannot be obtained despite the reading.

  In this multifunction device 1, the input range of the AFE 65 and the output voltage of the light source 61 are adjusted using the reading result detected using the white tape 80. The reference members such as the white tape 80 and the reference white plate 81 are generally specially processed and are more suitable for color tone correction than the original.

  Further, unlike shading correction in which it is difficult to ensure accuracy even if there is an abnormality in a part of the reading result, if the maximum value or minimum value of the reading result is known, even if there is an abnormality in the part of the reading result, the AFE 65 Adjustment accuracy of the input range and the output voltage of the light source 61 can be ensured. In the multi-function device 1, the white tape 80 is always used to adjust the input range of the AFE 65 and the output voltage of the light source 61, so that the tone of the image data I (x) can be accurately corrected.

<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) Although the above embodiment has been described using the multifunction machine 1, the present invention is not limited to this. For example, an apparatus having at least one of a scanner function, a copy function, and a facsimile function may be used.

(2) In the above embodiment, the MFP 1 has one ASIC 10, and the functions of the acquisition unit 21, the determination unit 22, the correction unit 23, and the like are executed by one CPU 20 having the ASIC 10. The present invention is not limited to this. For example, each unit may be configured by different CPUs, ASICs, and the like.

(3) In the above embodiment, the description has been given using the example in which the position of the document conveyed on the conveyance path 45 is detected using the document sensors 71 and 72. However, the document sensors 71 and 72 are not necessarily required. For example, the distance from the document tray 42 to the reading areas P and Q of the reading units 30 and 60 is known, and the motor M and the drive circuit 16 start from the conveyance to each reading position based on the rotational speed at which the roller 46 rotates. If the necessary conveyance time is known, the position of the document conveyed on the conveyance path 45 may be specified based on the necessary conveyance time.

(4) In the above embodiment, the example of adjusting the output voltage of the light source 61 in the RGB color light amount adjustment processing has been described. However, when the light receiving sensitivity of the linear image sensor 63 can be adjusted, the light source When the LEDs 61 are turned on, the light receiving sensitivity of the linear image sensor 63 may be changed. When the width of the input range of the AFE 65 can be adjusted, the width of the input range of the AFE 65 is changed in accordance with the voltage value detected by the linear image sensor 63 when each LED of the light source 61 is turned on. Also good.

(5) In the above embodiment, when determining whether or not a defect has occurred in the white tape 80, the shading data SD (x) acquired in the current reading process is used as the shading data acquired in the previous reading process. Although the description has been made using an example of comparison with SD (x), the shading data SD (x) used for comparison is not limited thereto. For example, shading data SD (x) acquired in a state where the document has not been conveyed using the ADF 40 may be used for comparison. In this case, the allowable range F (x) can be set based on the elapsed time from the start of use.

(6) Further, the reading results R (x), G (x), and B (x) acquired under the same conditions may be compared without comparing the shading data SD (x).

(7) The present invention is also effective for the reading unit 30 configured to be movable relative to the reference white plate 81. For example, when the position where the reading unit 30 reads the reference white plate 81 is normally determined according to the set value, if the position is contaminated, the reading unit 30 is used until the user changes the location. The document cannot be read. According to the present invention, in such a case, the CPU 20 uses the shading data SD (x) acquired from the margin portion Y1 of the document instead of the shading data SD (x) acquired from the reference white plate 81. By correcting the shading of the data I (x), the document can be read using the reading unit 30.

1: MFP, 3: image reading device, 16: drive circuit, 20: CPU, 21: acquisition unit, 22: determination unit, 23: correction unit, 26: device control unit, 27, 28: image processing unit, 30 : Reading unit, 35, 65: AEF, 40: ADF, 42: Document tray, 43, 44: Pressing member, 45: Transport path, 47: Paper discharge tray, 60: Reading unit, 70, 71, 72: Document sensor 80: White tape, 81: Reference white plate, R, G, B, K: Reading result, Wr, Wg, Wb, D: Reading gradation, SD: Shading data, HSD: Average shading data, I: Image data, F: Allowable range, Y1: Margin portion, Y2: Reading portion

Claims (7)

A reading section for reading a document;
A reference member disposed to face the reading unit;
A first acquisition unit that acquires first correction data for shading correction from a first reading result obtained by the reading unit reading the reference member;
A second acquisition unit that acquires second correction data for shading correction from a second reading result obtained by the reading unit reading a blank portion of the document;
A determination unit that determines whether or not there is an abnormality in the first reading result;
When the determination unit determines that there is no abnormality in the first reading result, the reading unit reads the original using the first correction data, and performs shading correction on the reading data. When the determination unit determines that there is an abnormality, a correction unit that performs shading correction on the read data using the second correction data;
An image reading apparatus comprising: The image reading apparatus according to claim 1,
The image reading apparatus, wherein the reference member is disposed so as not to move relative to the reading unit. The image reading apparatus according to claim 1, wherein:
Has a reference reading result,
The determination unit determines that the first reading result is abnormal when the first reading result is different from the reference reading result exceeding a predetermined degree of change. The image reading apparatus according to claim 3,
The reading unit repeatedly obtains the first reading result;
The determination unit uses the first reading result acquired last time as the reference reading result of the first reading result acquired this time. An image reading apparatus according to any one of claims 1 to 4,
When the determination unit determines that there is an abnormality in the first reading result, when the reading unit reads a plurality of documents, the reading unit reads the second reading result of each document, and 2 acquisition unit acquires each second correction data from each second reading result,
The second acquisition unit calculates average correction data obtained by averaging the second correction data acquired this time with the second correction data acquired before.
The image reading apparatus, wherein the correction unit performs shading correction on the read data using the average correction data. An image reading apparatus according to any one of claims 1 to 5,
The reading unit has light sources of a plurality of colors, detects each color reading result by causing each light source to emit light,
Furthermore,
A light amount adjustment unit that adjusts the light amount of the light source so that the maximum value of the reading results of each color that the reading unit has read the reference member matches in all colors;
An image reading apparatus comprising: A computer used in an image reading apparatus comprising a reading unit that reads a document and a reference member that is disposed to face the reading unit.
A first acquisition process of acquiring first correction data for shading correction from a first reading result obtained by the reading unit reading the reference member;
A second acquisition process for acquiring second correction data for shading correction from a second reading result obtained by the reading unit reading a blank portion of the document;
A determination process for determining whether or not there is an abnormality in the first reading result;
When the determination unit determines that there is no abnormality in the first reading result, the reading unit reads the original using the first correction data, and performs shading correction on the reading data. When the determination unit determines that there is an abnormality, a correction process for correcting shading of the read data using the second correction data;
A program for an image reading apparatus that executes

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