JP6127507B2 - Image reading apparatus and image reading program - Google Patents

Description

  The present invention relates to a technique for reading an image on a conveyed document sheet by a reading operation of an image reading unit at a reading position.

  There is an image reading apparatus of a type that reads an image on a conveyed document sheet by a reading operation of an image reading unit at a reading position. In this type of image reading apparatus, it is determined whether or not the leading edge or trailing edge of the document sheet has reached the reading position, and the determination result is used to determine, for example, the reading timing of the image reading unit or the document in the read image. Some of them are used to determine the image size.

  In an image reading apparatus as an example, an identification image such as a pattern whose color is switched along the main scanning direction, a barcode, or a specific pattern is drawn on a document pressing plate disposed opposite to the image reading unit. Then, by determining whether the image data read by the reading operation of the image reading unit is the identification image data or the other image data, the leading edge or the trailing edge of the document sheet has reached the reading position. Is determined (see Patent Document 1).

JP 2004-120425 A

  By the way, in the conventional image reading apparatus, the line cycle of the reading operation in the edge determination period for determining whether or not the leading edge of the document sheet has reached the reading position, and the document for reading the image on the document sheet thereafter. The line cycle of the reading operation in the reading period is always the same. In general, when the line cycle is changed, the conveyance speed is changed accordingly. For this reason, in the conventional image reading apparatus, when the line period is changed, the conveyance speed is changed not only in the reading period but also in the determination period. There has been a problem that inconveniences such as inability to transport at a desired transport speed occur in the end determination period.

  The present specification discloses a technique capable of suppressing the occurrence of inconvenience due to the same line cycle of the reading operation in the edge determination period and the document reading period.

  An image reading apparatus disclosed in this specification includes a conveyance unit that conveys a document sheet along a conveyance path, an image reading unit that performs a reading operation of reading an image at a reading position on the conveyance path, and a control unit. The control unit causes the image reading unit to perform a reading operation at a first line period before the original sheet reaches the reading position, and sequentially acquires first read image data. When the value of the read image changes between the acquisition process and the read image data acquired in the first image acquisition process, it is determined that the leading edge of the document sheet in the conveyance direction of the conveyance unit has reached the reading position. End determination processing, and after determining that the leading edge of the document sheet has reached the reading position, the image reading unit is caused to execute a reading operation at a second line cycle different from the first line cycle. Has a structure to perform a second image acquisition process for acquiring the second read image data of the image on the original sheet, the.

  According to this image reading apparatus, in the first image acquisition process for the edge determination process, the image reading unit executes the reading operation in the first line cycle and acquires the second image for reading the image on the document sheet. In the processing, the reading operation is executed in a second line cycle different from the first line cycle. Thereby, it is possible to suppress the occurrence of inconvenience due to the same line cycle of the reading operation in the edge determination period and the document reading period.

  In the image reading apparatus, the control unit may have a configuration in which the first line cycle is set as a fixed value and a change process for changing the second line cycle is executed.

  According to this image reading apparatus, it is possible to change the second line period with the first line period as a fixed value. Thereby, the second line cycle can be arbitrarily changed according to desired reading conditions such as reading resolution without changing the first line cycle.

  In the image reading apparatus, the control unit causes the image reading unit to perform a reading operation at the first line period, and acquires first correction data for correcting the first read image data. An acquisition process and a second correction data acquisition process for causing the image reading unit to execute a reading operation at the second line period and acquiring second correction data for correcting the second read image data are executed. You may have a structure.

  According to this image reading apparatus, the reading operation is executed in the first line cycle, the first correction data for correcting the first read image data is acquired, the reading operation is executed in the second line cycle, and the second Second correction data for correcting the read image data is acquired. Thereby, it can correct | amend appropriately based on the correction data acquired on the same conditions with respect to each read image data.

  In the image reading apparatus, the image reading unit includes a plurality of light emitting elements having different emission colors, a color reading operation for causing the plurality of light emitting elements to emit light, and light emission of any one of the plurality of light emitting elements. In the first image acquisition process, the image reading unit performs the monochrome reading operation, and in the second image reading process, the image reading unit performs the color reading. An operation may be executed.

  According to this image reading apparatus, even when the image on the original sheet is read in color, the power consumption of the light emitting element can be suppressed by executing the monochrome reading operation in the edge determination.

  The present invention can be realized in various modes such as an image reading apparatus, an image reading method, a computer program for realizing the functions of these methods or apparatuses, and a recording medium on which the computer program is recorded.

  According to the invention disclosed in this specification, it is possible to suppress inconvenience due to the same line cycle of the reading operation in the edge determination period and the document reading period.

1 is a block diagram showing an electrical configuration of a scanner according to an embodiment. Overview of scanner configuration Schematic configuration diagram of image reading unit and ADF Flowchart showing reading control processing (part 1) Flowchart showing reading control processing (part 2) Flowchart showing reading control processing (part 3)

  A scanner 1 according to an embodiment will be described with reference to FIGS. In the following description, the left side of FIG. 2 is the front side (F) of the scanner 1, the front side of the paper is the right side (R) of the scanner 1, and the upper side of the paper is the upper side (U) of the scanner 1.

(Electrical configuration of the scanner)
As shown in FIG. 1, the scanner 1 includes a control unit 2, an image reading unit 3, a device moving mechanism 4, an automatic document feeder (hereinafter referred to as “ADF”) 5, an operation unit 6, a display unit 7, and a front sensor 8. Etc.

  The control unit 2 includes a central processing unit (hereinafter referred to as CPU) 11, a ROM 12, a RAM 13, and an image processing unit 14. The ROM 12 stores a program (an example of an image reading program) for executing a reading control process, which will be described later, and a program for executing various operations of the scanner 1. The CPU 11 controls each unit of the scanner 1 according to a program read from the ROM 12. In addition to the ROM 12 and RAM 13, the medium for storing the various programs may be a non-volatile memory such as a CD-ROM, a hard disk device, or a flash memory.

  The RAM 13 is an example of a storage unit. The read data of the pixel row corresponding to the read image read by the image reading unit 3 is AD-converted by an AD conversion unit (not shown) and is given to the image processing unit 14. The image processing unit 14 is a hardware circuit dedicated to image processing, and performs processing such as shading correction and gamma correction on the AD-converted read data, and then stores it in the RAM 13.

  The device moving mechanism 4 includes, for example, a stepping motor 4A and a motor driver 4B, and can reciprocate the image reading unit 3 in the front-rear direction. For example, when a clock signal is input from the CPU 11, the motor driver 4 </ b> B updates a signal instructing the excitation phase for each pulse of the clock signal, and supplies a current to the coil based on the signal, thereby stepping motor 5A is rotated by one step (predetermined angle).

  The ADF 5 includes, for example, a stepping motor 5A and a motor driver 5B, and rotationally drives each roller 27 described later. For example, when a clock signal is input from the CPU 11, the motor driver 5 </ b> B updates a signal instructing an excitation phase for each pulse of the clock signal, and supplies a current to the coil based on the signal to thereby generate a stepping motor. 5A is rotated by one step (predetermined angle).

  The operation unit 6 has a plurality of buttons, and allows a user to perform various input operations such as selection of a reading mode and selection of a reading resolution of a reading operation. Reading mode selection targets include a color mode and a monochrome mode. The color mode is a mode in which an image on the original sheet M is read as a color image by a color reading operation described later, and the monochrome mode is an image in which an image on the original sheet M is read as a monochrome image by a monochrome reading operation described later. Mode.

  It is assumed that reading resolution selection targets include 300 dpi (dots per inch), 600 dpi, and 1200 dpi. The display unit 7 includes a liquid crystal display, a lamp, and the like, and can display various setting screens and operation states of the apparatus. The configuration of the image reading unit 3, the ADF 5, and the front sensor 8 will be described below.

(Configuration of image reading unit and ADF)
As shown in FIG. 2, a partition member 20, an ADF glass 21, and an FB (flat bed) glass 22 are provided on the upper surface of the scanner body 1A. The partition member 20 is provided between the ADF glass 21 and the FB glass 22. A white reference plate 20A is provided on the lower surface of the partition member 20, and the white reference plate 20A is a white member having a substantially uniform light reflectance. Moreover, the part adjacent to the white reference board 20A among the lower surfaces of the partition member 20 is black.

  A cover 23 covering these glasses 21 and 22 is provided on one end side of the upper surface of the scanner body 1A so as to be openable and closable. In the cover 23, the ADF 5 and the front sensor 8 described above are provided, and the image reading unit 3 and the device moving mechanism 4 described above are provided below the glasses 21, 22 and the like.

  Specifically, the cover 23 is provided with a document tray 24 on which the document sheet M is disposed, and a discharge tray 25 disposed above the document tray 24. Further, the front sensor 8 is provided on the leading end side of the document tray 24. The front sensor 8 is a document presence / absence sensor that detects the presence / absence of the document sheet M on the document tray 24 at the detection position R0 set on the front end side of the document tray 24, and transmits the detection result to the control unit 2. .

  Further, a transport path 26 is formed in the cover 23 for folding the document sheet M from the document tray 24 into a U shape and transporting it to the discharge tray 25. The ADF 5 is an example of a transport unit. The ADF 5 includes a plurality of transport rollers 27 and a document pressing member 28 disposed in the transport path 26, and the document roller M is transported by rotating the transport rollers 27. 26 is configured to be automatically conveyed along the line 26.

  The document pressing member 28 is provided at a position facing the image reading unit 3 through the ADF glass 21 when the image reading unit 3 is positioned at the ADF reading position X1 (see FIG. 2). It is. Specifically, the document pressing member 28 is fixed to a predetermined portion inside the cover 23, and the document pressing member 28 faces the upper surface of the ADF glass 21 when the cover 23 is in the closed posture.

  The image reading unit 3 is a reading device having a CIS (Contact Image Sensor). A specific configuration of the image reading unit 3 and an arrangement relationship with the document pressing member 28 will be described later. Note that the image reading unit 3 is not limited to the CIS, and may be configured to include, for example, a CCD (Charge Coupled Drive Image Sensor). Further, the image reading unit 3 is provided so as to be movable in the front-rear direction below the ADF glass 21 and the FB glass 22 by the device moving mechanism 4 (see thick black arrows in FIG. 2).

  Thereby, the scanner 1 can execute ADF reading and FB reading. The ADF reading is an operation in which the image reading unit 3 is stopped at the ADF reading position X1 facing the document pressing member 28 and an image on the document sheet M conveyed by the ADF 5 is read. The FB reading is an operation of reading the image of the original sheet M placed on the FB glass 11B while moving the image reading unit 3 along the FB glass 11B by the device moving mechanism 4.

(Specific configuration of image reading unit and document pressing member)
As shown in FIG. 3, the image reading unit 3 includes a light emitting unit 31 and a light receiving unit 32. In FIG. 3, the light paths of the light beams LR, LG, and LB of each color are schematically illustrated so that they can be distinguished, and the range of the reading position R1 is also illustrated large. Also, the drawing shows a state in which the light beams LR, LG, and LB of each color are reflected by the facing surface of the document pressing member 28.

  Specifically, the light emitting unit 31 includes an LED substrate 33 and a light guide 34. The LED substrate 33 has an R color LED (light emitting diode) 34R that emits red (R) light LR, a G color LED 34G that emits green (G) light LG, and a B that emits blue (B) light LB. The color LEDs 34B are arranged at positions shifted from each other along the front-rear direction (the transport direction of the transport path 26). The light guide 34 is an optical member that guides the light beams LR, LG, and LB from the LEDs 34R, 34G, and 34B to the reading position R1. The LEDs 34R to 34B are examples of light emitting elements.

  The light receiving unit 32 includes a light receiving lens 35 and a light receiving substrate 36. The light receiving lens 35 is an optical member that guides light from the reading position R 1 side to the light receiving substrate 36. The light receiving substrate 36 has a configuration in which a plurality of light receiving elements (not shown) are arranged side by side in the left-right direction, in other words, in the main scanning direction. The emission directions of the light beams LR, LG, and LB of each color are inclined with respect to the facing direction between the light receiving unit 32 and the facing surface of the document pressing member 28.

  With the above configuration, the image reading unit 3 sequentially reads line-shaped images along the main scanning direction (left-right direction) orthogonal to the transport direction at the reading position R1, and the data (reading) of the pixel columns of each line. An example of image data (hereinafter referred to as line data) is output. The image reading unit 3 can selectively execute a color reading operation and a monochrome reading operation.

  Specifically, the image reading unit 3 can selectively execute a color reading operation and a monochrome reading operation. In the color reading operation, the LEDs 34R, 34G, and 34B of the light emitting unit 31 are caused to emit light in a time-sharing manner, the light beams LR, LG, and LB reflected at the reading position R1 are received by the light receiving unit 32, and RGB color line data is obtained. This is a reading operation for sequentially outputting a set of color line data. In the monochrome reading operation, one of the LEDs 34R, 34G, and 34B (for example, LED 34G) of the light emitting unit 31 is caused to emit light, and the light of the one color reflected at the reading position R1 is received by the light receiving unit 32. This is a reading operation that outputs sequentially.

(Reading control processing)
When the user selects a color mode as a reading mode on the operation unit 6 and selects one of the reading resolutions to give a reading instruction, the control unit 2 controls the document tray 24 on the basis of the detection result of the front sensor 8. 4 to 6 are executed on the condition that it is determined that the original sheet exists. By this reading control process, the scanner 1 performs a reading operation at the edge determination line period in ADF reading, and the leading edge (hereinafter simply referred to as the leading edge) in the conveyance direction of the original sheet M has reached the reading position R1. After that, the image on the original sheet M is read while performing the reading operation with the original reading line cycle different from the edge determination line cycle. The edge determination line cycle is an example of a first line cycle, and the document reading line cycle is an example of a second line cycle.

  The line period is a time corresponding to the time for which the image reading unit 3 outputs the read value from each LED 34 when reading the image for one line. An image for one line is an image for one color line in a monochrome reading operation, and an image for three color lines in a color reading operation. Also, the line cycle depends on the time difference between the start timing for reading an image for one line and the start timing for reading an image for the next line when the image reading unit 3 continuously reads images for a plurality of lines. It was time.

  Here, the control unit 2 sets the line cycle to a longer time as the processing load of the reading operation for one line is larger, and accordingly sets the conveyance speed of the original sheet M by the ADF 5 to a slower speed. For example, the control unit 2 sets the line cycle to a longer time during the color reading operation than during the monochrome reading operation. Further, the control unit 2 sets the line cycle to a longer time as the selected reading resolution is higher.

  The CPU 11 controls the device moving mechanism 4 to move the image reading unit 3 to the white reference reading position X0 (see FIG. 2) immediately below the partition member 20 (S1). Specifically, the CPU 11 performs a reading operation while moving the image reading unit 3, and when the read image is switched from the white image on the white reference plate 20 </ b> A to the black image of the adjacent portion, the image reading is performed. The unit 3 determines that the white reference reading position X0 has been reached, and stops the device moving mechanism 4.

  Next, the CPU 11 sets a document reading line cycle as a line cycle of the reading operation (S2). Here, as described above, the CPU 11 sets the document reading line cycle to a longer time as the selected reading resolution is higher. Hereinafter, it is assumed that the CPU 11 sets a document reading line period corresponding to 1200 dpi. Thereafter, the CPU 11 and the image processing unit 14 execute a process for acquiring black reference data using the document reading line cycle (S3). Specifically, the CPU 11 causes the image reading unit 3 to output line data in the original reading line cycle without causing the light emitting unit 31 to emit light, and the image processing unit 14 converts the line data to black for original reading. It is stored in the RAM 13 as reference data.

  Next, the CPU 11 sets an end determination line cycle as the line cycle of the reading operation (S4). Here, the CPU 11 sets the end determination line cycle to a predetermined fixed cycle (time) regardless of the selected reading resolution level. The edge determination line cycle may be different from a plurality of line cycles corresponding to each of a plurality of reading resolutions selectable by the scanner 1, for example, but may be the same cycle as any one of the plurality of line cycles. preferable.

  For example, if the edge determination line cycle is set to a line cycle corresponding to the minimum reading resolution (300 dpi), in the leading edge determination period for determining whether or not the leading edge of the document sheet M has reached the reading position R1. The original sheet M is conveyed at high speed, and it can be determined at an early stage whether or not the leading edge of the original sheet M has reached the reading position R1. On the other hand, if the line cycle for edge determination is set to a line cycle corresponding to the maximum reading resolution (1200 dpi), the document sheet M is conveyed at low speed, and whether or not the leading edge of the document sheet M has reached the reading position R1 is determined. It can be determined with high accuracy. The scanner 1 may have a configuration in which the edge determination line cycle can be changed in advance independently of the document reading line cycle, for example, by the operation of the operation unit 6 by the user.

  Thereafter, the CPU 11 and the image processing unit 14 execute processing for acquiring black reference data using the end determination line cycle (S5). Specifically, the CPU 11 causes the image reading unit 3 to output line data in the end determination line cycle without causing the light emitting unit 31 to emit light, and the image processing unit 14 converts the line data to the end determination black. It is stored in the RAM 13 as reference data.

  Next, the CPU 11 resets the original reading line cycle as the line cycle of the reading operation (S6), causes the image reading unit 3 to execute the reading operation in the original reading line cycle, and the line data from the light receiving unit 32. Based on the above, the light amount is adjusted so that the light emission amount of each LED 34 becomes a predetermined target amount (S7). As described above, if the light amount adjustment is performed using the document reading line cycle, the reading operation can be accurately performed in the document reading period for reading an image on the document sheet M described later.

  Next, the CPU 11 and the image processing unit 14 execute processing for acquiring the document reading white reference data using the document reading line cycle (S8). Specifically, the CPU 11 causes the image reading unit 3 to perform color reading operation at a document reading line cycle to output color line data, and the image processing unit 14 converts the color line data to white for document reading. It is stored in the RAM 13 as reference data.

  When the CPU 11 acquires the original reading black reference data and the original reading white reference data, the image processing unit 14 generates the original reading shading data based on these data, and stores it in the RAM 13 (S9). The original reading shading data is correction data for correcting original reading line data output from the image reading unit 3 during the original reading period. As described above, by generating the original reading shading data based on the original reading white reference data acquired at the same original reading line period as the original reading period, it is possible to appropriately correct the original reading line data. it can. Note that the processes of S3, S8, and S9 are an example of the second correction data acquisition process, and the document reading shading data is an example of the second correction data.

  When generating the document reading shading data, the CPU 11 resets the end determination line cycle as the line cycle of the reading operation (S10), and uses the end determination line cycle together with the image processing unit 14 for edge determination. A process for acquiring white reference data is executed (S11). Specifically, the CPU 11 and the image processing unit 14 cause the image reading unit 3 to execute monochrome reading operation in the end determination line cycle to output monochrome line data, and the image processing unit 14 outputs the monochrome line data. Then, it is stored in the RAM 13 as edge reference white reference data.

  When the CPU 11 acquires the edge determination black reference data and the edge determination white reference data, the CPU 11 causes the image processing unit 14 to generate edge determination shading data based on these data and store the generated edge determination shading data in the RAM 13 (S12). The edge determination shading data is correction data for correcting the edge determination line data output from the image reading unit 3 in the edge determination period. Thus, by generating edge determination shading data based on the edge determination white reference data acquired at the same edge determination line period as the edge determination period, the edge determination line data can be appropriately corrected. it can. Note that the processing of S5, S11, and S12 is an example of first correction data acquisition processing, and the edge determination shading data is an example of first correction data.

  Next, the CPU 11 controls the device moving mechanism 4 to move the image reading unit 3 from the white reference reading position X0 to the ADF reading position X1 (see FIG. 2) (S13). Then, the CPU 11 causes the image reading unit 3 to execute a monochrome reading operation on the facing portion of the document pressing member 28 in the edge determination line cycle (S14). Then, the CPU 11 corrects the monochrome data output from the image reading unit 3 to the image processing unit 14 using the edge determination shading data, and uses the corrected monochrome data as the first reference reading data in the RAM 13. (S15).

  Next, the CPU 11 causes the image reading unit 3 to perform a color reading operation on the facing portion of the document pressing member 28 in the document reading line cycle (S16). Then, the CPU 11 corrects the color data output from the image reading unit 3 to the image processing unit 14 using the shading data for document reading, and uses the corrected color data as the second reference reading data in the RAM 13. (S17).

  When the CPU 11 acquires the first reference read data and the second reference read data, the CPU 11 resets the end determination line cycle as the line cycle of the reading operation (S21), and the ADF 5 carries the conveyance corresponding to the end determination line cycle. The conveying operation of the document sheet M is started at the edge determination speed which is the speed (S22). Then, the CPU 11 causes the image reading unit 3 to read an image for one line by the monochrome reading operation in the edge determination line cycle (S23), and causes the image processing unit 14 to output the monochrome line data output from the image reading unit 3. Is corrected using the edge determination shading data (S24). The corrected monochrome line data is the edge determination time line data. The process of S23 is an example of a first image acquisition process.

CPU11, by determining whether the end determination time line data value (for example, the number of edge pixels, an average value or most frequent pixel values of each pixel value) or matches the value of the first reference reading data, A leading edge determination process for determining whether or not the leading edge of the document sheet M has reached the reading position R1 is executed (S25). Since the leading edge of the document sheet M has not yet reached the reading position R1 at the beginning of the execution of the process of S22, the image reading unit 3 performs a monochrome reading operation on the opposite portion of the document pressing member 28. become. For this reason, the CPU 11 determines that the value of the end determination line data is substantially equal to the value of the first reference read data (S25: YES).

  Next, when the CPU 11 determines that the original sheet M is not conveyed by the first distance from the start of the conveying operation in S22 (S27: NO), the CPU 11 returns to S23. The first distance is set to a distance sufficient for the leading edge of the document sheet M to be conveyed from the document tray 24 to the reading position R1, and the CPU 11 makes the determination in S27 from the number of steps of the stepping motor 4A, for example. It can be carried out.

When the leading edge of the document sheet M reaches the reading position R1, the image reading unit 3 reads the document sheet M from the facing portion of the document pressing member 28. Accordingly, the value of the line data at the time of edge determination is The value changes from the value of the first reference read data. For this reason, the CPU 11 determines that the value of the edge determination line data does not match the value of the first reference read data (S25: NO), and proceeds to S31 of FIG.

If the CPU 11 determines that the value of the line data at the end determination coincides with the value of the first reference read data even if the first distance is transported from the start of the transport operation in S22 (S25: YES and S27: YES) For example, if an error occurs in which the leading edge of the document sheet M does not reach the reading position R1 due to the document sheet M being jammed in the middle of the conveyance path 26, the error is notified to the outside (S28). For this notification, various notification methods can be used such as displaying error information on the display unit 7 or outputting a sound to a sounding device (not shown). After notifying the error, the CPU 11 causes the ADF 5 to stop the conveyance operation regardless of the presence or absence of the document sheet M on the document tray 24, and ends the reading control process.

If the CPU 11 determines that the value of the line data at the end determination is no longer coincident with the value of the first reference read data before transporting the first distance from the start of the transport operation in S22 (S25: NO), the CPU 11 The conveying operation is stopped (S26), and the process proceeds to S31 in FIG.

  In S31, the CPU 11 resets the original reading line period as the line period of the reading operation, and the ADF 5 performs the original sheet M conveying operation at the original reading speed that is the conveying speed corresponding to the original reading line period. Is started (S32). Then, the CPU 11 causes the image reading unit 3 to read an image for one line by a color reading operation in the original reading line cycle (S33), and causes the image processing unit 14 to output the color line data output from the image reading unit 3. Is corrected using the document reading shading data (S34). The corrected color line data is the original reading line data. The process of S33 is an example of a second image acquisition process.

CPU11, by determining whether or not the document reading time of the line data value (for example, the number of edge pixels, an average value or most frequent pixel values of each pixel value) or matches the value of the second reference reading data, A trailing edge determination process for determining whether the trailing edge of the document sheet M has reached the reading position R1 is executed (S35). At the beginning of the execution of the process of S32, since the trailing edge of the document sheet M has not yet reached the reading position R1, the image reading unit 3 performs a color reading operation on the document sheet M. For this reason, the CPU 11 determines that the value of the original reading line data does not match the value of the second reference read data (S35: NO).

  Next, when the CPU 11 determines that the original sheet M is not conveyed by the second distance from the start of the conveying operation in S32 (S37: NO), the CPU 11 returns to S33. The second distance is set to a distance longer than the maximum length in the conveyance direction of the document sheet M that can be conveyed by the ADF 5, for example, and the CPU 11 can perform the determination of S37 from the number of steps of the stepping motor 4A, for example. .

When the trailing edge of the document sheet M reaches the reading position R1, the image reading unit 3 reads the opposite portion of the document pressing member 28 from the document sheet M, and accordingly, the value of the line data at the time of document reading is changed. , And changes to a value that matches the value of the second reference read data. Therefore, CPU 11 determines that the value of the line data at a time of document reading matches the value of the second reference reading data (S35: YES), the process proceeds to S39.

If the CPU 11 determines that the value of the line data during document reading does not match the value of the second reference read data even after being transported by the second distance from the start of the transport operation in S32 (S35: NO and S37: YES), for example, an error that the trailing edge of the document sheet M does not reach the reading position R1 due to the document sheet M being jammed in the middle of the conveyance path 26, and the like are notified to the outside (S38). For this notification, various notification methods can be used such as displaying error information on the display unit 7 or outputting a sound to a sounding device (not shown). After notifying the error, the CPU 11 causes the ADF 5 to stop the conveyance operation regardless of the presence or absence of the document sheet M on the document tray 24, and ends the reading control process.

If the CPU 11 determines that the value of the line data at the time of document reading matches the value of the second reference reading data before conveying the second distance from the start of the conveying operation in S32 (S35: YES), The ADF 5 stops the conveying operation, the original reading line data is stored in the RAM 13 as original image data (S36), and the process proceeds to S39.

  In S39, when the CPU 11 determines that the document sheet M is present in the document tray 24 (S39: YES), the CPU 11 returns to S21 in FIG. 5 and determines that there is no document sheet M in the document tray 24 (S39: NO). After the document sheet M that has been read last is discharged onto the discharge tray 25, the ADF 5 stops the conveying operation (S40), and the reading control process is terminated. When the user selects the monochrome mode with the operation unit 6 and gives a reading instruction, the control unit 2 executes a monochrome reading operation in S8, S16, and S33.

(Effect of this embodiment)
According to the present embodiment, the image reading unit 3 executes the reading operation in the edge determination line cycle in the leading edge determination process, and the edge determination line cycle in the document reading process for reading an image on the document sheet. Can perform reading operations with different document reading line cycles. Thereby, it is possible to suppress the occurrence of inconvenience due to the same line cycle of the reading operation in the trailing edge determination period and the document reading period.

  Further, the scanner 1 can change the document reading line cycle by setting the edge determination line cycle to a fixed value. Thereby, the document reading line cycle can be arbitrarily changed according to desired reading conditions such as reading resolution without changing the edge determination line cycle.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and includes, for example, the following various aspects.

  In the embodiment described above, the scanner 1 having only the scanner function is given as an example of the image reading apparatus. However, the present invention is not limited to this, and the image reading apparatus may be a multifunction machine capable of executing a plurality of functions such as a copy function, a facsimile machine, or the like in addition to the scan function. Further, the image reading apparatus may be configured such that the document tray is disposed above the discharge tray.

  In the above embodiment, the control unit 2 is configured to execute the reading control process by the CPU 11 and hardware circuits such as the image processing unit 14. However, the present invention is not limited to this, and the control unit 2 is configured to execute read control processing or the like by only one or a plurality of CPUs, or to execute read control processing or the like only by a hardware circuit such as an ASIC (Application Specific Integrated Circuit). But you can.

  In the above embodiment, the image reading unit 3 has a configuration in which the light emitting unit 31 is disposed on the downstream side of the light receiving unit 32 with respect to the transport direction. However, the configuration is not limited thereto, and the image reading unit 3 may have a configuration in which the light emitting unit 31 is disposed on the upstream side of the light receiving unit 32. Further, the emission directions of the light beams LR, LG, and LB of each color may not be parallel to each other.

  The control unit 2 may be configured to execute a color reading operation in S11, S14, and S23. However, even when the image on the original sheet M is read in the color mode as in the above embodiment, the power consumption of the light emitting element can be suppressed by executing the monochrome reading operation in the edge determination.

  The controller 2 may generate the document reading shading data in S9 based on the white reference data acquired in S3 and S8 with a line cycle different from the document reading line cycle. Further, the control unit 2 may be configured to generate the edge determination shading data in S12 based on the white reference data acquired in S5 and S11 with a line period different from the edge determination line period. However, with the configuration of the above embodiment, the original reading line data and the edge determination line data can be corrected more appropriately.

  The control unit 2 may be configured to execute the processes in FIGS. 4 to 6 in an order different from that in FIG. 4. For example, the control unit 2 may be configured to execute the processes of S2 and S3 and the processes of S4 and S5 in the reverse order of FIG. Moreover, the structure which performs the process of S6-S9 and the process of S10-S12 in the order reverse to FIG. 4 may be sufficient as the control part 2. FIG. Further, the control unit 2 may be configured to execute the processes of S14 and S15 and the processes of S16 and S17 in the reverse order of FIG.

1: Scanner 3: Image reading unit 4: Device moving mechanism 5: ADF 26: Conveyance path M: Document sheet R1: Reading position

Claims (4)

A transport unit that transports a document sheet along a transport path;
An image reading unit that performs a reading operation of reading an image at a reading position on the conveyance path;
A document pressing member disposed at a position facing the image reading unit positioned at the reading position;
A control unit,
The controller is
A first reference reading data acquisition process for causing the image reading unit to execute a reading operation of reading an image of the document pressing member at a first line period and acquiring first reference reading data;
A second reference reading data acquisition process for causing the image reading unit to perform a reading operation of reading an image of the document pressing member at a second line period different from the first line period, and acquiring second reference reading data;
A first transport operation for transporting the document sheet to the transport unit at an edge determination speed is started, and the image reading unit performs a scanning operation at the first line period before the document sheet reaches the scanning position. First image acquisition processing for sequentially acquiring first read image data;
When the first read image data acquired in the first image acquisition process changes from image data that matches the first reference read data to image data that does not match the first reference read data, the transport of the transport unit An edge determination process for determining that the leading edge of the document sheet in the direction has reached the reading position;
After determining that the leading edge of the document sheet has reached the reading position, a second transport operation for transporting the document sheet to the transport unit at a document reading speed is started, and the image reading unit is configured to perform the second line cycle. A second image acquisition process in which the reading operation is executed and the second read image data is sequentially acquired;
When the second read image data acquired in the second image acquisition process changes from image data that does not match the second reference read data to image data that matches the second reference read data, the transport of the transport unit A trailing edge determination process for determining that the trailing edge of the document sheet in the direction has reached the reading position;
An image reading apparatus comprising: a stop process for causing the transport unit to stop the second transport operation after determining that the trailing edge of the document sheet has reached the scanning position. The image reading apparatus according to claim 1,
The controller is
An image reading apparatus having a configuration in which a change process for changing the second line period is performed with the first line period as a fixed value. The image reading apparatus according to any one of claims 1 to 2,
The image reading unit includes a plurality of light emitting elements having different emission colors, a color reading operation for causing the plurality of light emitting elements to emit light, and a monochrome reading for causing any one of the plurality of light emitting elements to emit light. It is a configuration that can perform the operation,
An image reading apparatus that causes the image reading unit to execute the monochrome reading operation in the first image acquisition process, and causes the image reading unit to execute the color reading operation in the second image acquisition process. A transport unit that transports a document sheet along a transport path;
An image reading unit that performs a reading operation of reading an image at a reading position on the conveyance path;
An image reading apparatus comprising: a document pressing member disposed at a position facing the image reading unit located at the reading position;
A first reference reading data acquisition process for causing the image reading unit to execute a reading operation of reading an image of the document pressing member at a first line period and acquiring first reference reading data;
A second reference reading data acquisition process for causing the image reading unit to perform a reading operation of reading an image of the document pressing member at a second line period different from the first line period, and acquiring second reference reading data;
A first transport operation for transporting the document sheet to the transport unit at an edge determination speed is started, and the image reading unit performs a scanning operation at the first line period before the document sheet reaches the scanning position. First image acquisition processing for sequentially acquiring first read image data;
When the first read image data acquired in the first image acquisition process changes from image data that matches the first reference read data to image data that does not match the first reference read data, the transport of the transport unit An edge determination process for determining that the leading edge of the document sheet in the direction has reached the reading position;
After determining that the leading edge of the document sheet has reached the reading position, a second transport operation for transporting the document sheet to the transport unit at a document reading speed is started, and the image reading unit is configured to perform the second line cycle. A second image acquisition process in which the reading operation is executed and the second read image data is sequentially acquired;
When the second read image data acquired in the second image acquisition process changes from image data that does not match the second reference read data to image data that matches the second reference read data, the transport of the transport unit A trailing edge determination process for determining that the trailing edge of the document sheet in the direction has reached the reading position;
An image reading program comprising: a stop process for causing the transport unit to stop the second transport operation after determining that the rear end of the document sheet has reached the scanning position.

Images