JP2016163231A - Image reading apparatus, control method therefor, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reading technique capable of accurately reading an image while adjusting a document feed-in reading position.SOLUTION: While no document is fed by an ADF unit, background images are sampled by a reading unit at predetermined intervals regarding a predetermined range at a downstream side of a center of a platen guide 71. Luminance value distribution in a sub scan direction is calculated from a luminance value average for one line in a main scan direction, thereby detecting an edge part between a white sheet 71a and a sheet metal part of the platen guide 71. Based on the edge part, a reading position is set at a predetermined position closer to the white sheet 71a. At such a time, however, if it is discriminated from the luminance value distribution that the ADF unit is not rightly closed, abnormality caution display or display that calls re-adjustment is performed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image reading technique for reading an image of a document.

  2. Description of the Related Art Conventionally, there has been known an image reading apparatus in which a reading optical system is fixed and an original is automatically conveyed into the apparatus by ADF to read the original. When reading a document conveyed by the ADF, the document is exposed while the document is automatically conveyed to the reading position by the ADF with the reading unit fixed at a predetermined reading position, and reflected light from the document is detected. Is imaged on a reading unit (image sensor) through a reading optical system to photoelectrically convert and read. At this time, the position where the document conveyed by the ADF is closest to the flow reading glass is often set as a reading position (flow reading position) at the time of the flow reading by the ADF. Then, in order to determine the above reading position, the flow reading position adjustment is performed.

  For example, as disclosed in Patent Document 1, a reading unit is used to optically read a platen roller arranged to convey a document directly above a flow reading glass, and a position where the brightness of an image obtained thereby is maximized. It is set as a sink reading position.

JP 2000-151925 A

  In Patent Document 1, when determining the position of the flow reading, the reading unit reads the luminance of the platen roller immediately above the flow reading glass. However, if the ADF is opened and closed during reading of the platen roller, the correct flow reading is performed. The position cannot be detected.

  Some recent image reading apparatuses are configured with a platen guide instead of a platen roller so that a document conveyed by ADF can be pressed on a flat surface. In the case of the platen guide, since the pressing plate for pressing the document is flat, there is no position where the luminance is maximized, and the detected luminance is constant under an ideal environment. Therefore, by detecting the end portion (edge portion) of the platen guide, the platen guide and the end portion (edge portion) are read when adjusting the flow reading position. And the place which moved only the predetermined distance upstream from the edge part is set as the flow reading position.

  However, the platen guide may erroneously detect the end by opening and closing the ADF while adjusting the flow reading position, and the flow reading position may deviate from the ideal position. Further, if the flow reading position is shifted, the illuminance on the original surface varies, and as a result, the reading density of the image may vary, and the reading quality may not be guaranteed.

  The present invention has been made in view of the above problems, and an object thereof is to provide a reading technique capable of accurately reading an image.

In order to achieve the above object, an image reading apparatus according to the present invention comprises the following arrangement. That is,
Reading means capable of reading an image of a document on a reading position;
A conveying means provided so as to be openable and closable with respect to the reading position, and conveying the document to the reading position;
Detecting means for detecting the reading position based on a reading result by the reading means in a state where the original is not conveyed by the conveying means;
Determining means for determining whether or not the detection means can detect the reading position based on a read image by the reading means in a state in which the original is not conveyed by the conveying means;
The detection unit detects the reading position when the determination unit determines that the reading position can be detected by the detection unit.

  According to the present invention, an image can be read with high accuracy.

It is a sectional side view showing the composition of an image reading device. It is a block diagram showing a configuration of a reading control circuit of the image reading apparatus. FIG. 3 is a partially enlarged view of the periphery of the platen guide of the image reading apparatus. It is a figure for demonstrating distribution of the luminance value of the image (background image) acquired by adjustment of a flow reading position. It is a figure which shows distribution of the luminance value at the time of the flow-reading position adjustment in a normal state. It is a figure which shows distribution of the luminance value at the time of the flow-reading position adjustment in an abnormal state. It is a flowchart which shows the adjustment process regarding adjustment of a flow reading position. It is a figure which shows distribution of the luminance value in the case of adjusting a flow reading position. It is a flowchart which shows an image reading process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The image reading apparatus of the present embodiment can be realized by, for example, a scanner device, and may be mounted on the image forming apparatus or may be used alone. In addition, an image forming apparatus equipped with this image reading apparatus can be realized. This image forming apparatus can print an image on a recording medium such as a printing apparatus, a copier, a multifunction peripheral (MFP), and a facsimile apparatus. There is a device to form. Here, the multifunction peripheral has, for example, at least two or more of a plurality of types of functions including a copying function, a printing function, a scanner function, and a facsimile function.

  FIG. 1 is a side sectional view showing the structure of an image reading apparatus that optically reads an image of a document. The image reading apparatus shown in FIG. 1 includes a scanner unit 1 and an ADF unit 7.

  The ADF unit 7 serving as a document conveying unit is connected at the end of the housing of the scanner unit 1 and has a structure that can be opened and closed in a predetermined direction with the end as a base point. By opening the ADF unit 7, the original 74 is placed on the original platen glass 14 (also referred to as platen glass), and the reading unit 13 scans, whereby the image of the original 74 can be read. The ADF unit 7 is provided with a document tray 72 (ADF paper feed tray). When a plurality of documents 74 are placed on the document tray 72, the document unit 74 feeds the documents 74 one by one. 1 can read the image of the original 74 continuously. The scanner unit 1 uses a reading unit 13 (reading unit) composed of a CCD, a CIS, or the like to irradiate light on a document 74, receive reflected light from the document 74, and photoelectrically convert the light to convert an image signal. Generate. In this way, image data is generated by reading the image of the document 74.

  The reading unit 13 includes an illuminating unit 131, an optical lens 133, and an imaging unit 134, and is in close contact with the reading glass (the original table glass 14 or the flow reading glass 15) on the side opposite to the side on which the original 74 is placed. Placed in.

  The illumination unit 131 illuminates the document 74 from a direction inclined with respect to the document table glass 14. The optical lens 133 is a lens array configured such that a plurality of Selfoc lenses (registered trademark) are arranged in an array. The optical lens 133 guides the light emitted from the illumination unit 131 and reflected by the document surface to a predetermined image formation position, and converges the reflected light from the document 74 and reads it at an equal magnification. The imaging unit 134 includes an optical system such as a plurality of photoelectric conversion elements arranged in a predetermined direction, and images the light guided to a predetermined imaging position by the optical lens 133.

  As described above, the reading unit 13 reads the original 74 placed on one display on the reading glass or the original 74 sequentially conveyed on one surface of the reading glass from the other surface side of the reading glass. .

  In the present embodiment, it is assumed that the imaging unit 134 is a CMOS sensor. Image data of the document 74 obtained by imaging by the imaging unit 134 is stored in, for example, the RAM 51 (FIG. 2) functioning as an image storage unit. The reading unit 13 having such a configuration is attached to the driving belt 16 via the carriage 19, and the driving force of the scanner motor 18 is transmitted via the driving belt 16. (Sub-scanning direction (conveyance direction of document 74)).

  In the scanner unit 1, while the reading unit 13 is moved in the sub-scanning direction H by the driving force of the scanner motor 18, the reading unit 13 is electrically moved in a direction (generally intersecting) with the paper surface of the drawing (generally intersecting) direction (main scanning direction). The image of the original 74 is read by scanning. In general, a stepping motor, a DC motor, or the like is used as the scanner motor 18. Further, at the time of image reading, the white reference plate 12 provided at the end of the platen glass 14 is irradiated with light, and a reference signal for performing shading correction is obtained from the reflected light. Usually, the arrangement direction of a plurality of photoelectric conversion elements corresponds to the main scanning direction.

  The ADF unit 7 feeds a plurality of documents 74 placed on the document tray 72 with the surface facing up from the uppermost document 74 to the separation unit 732 by the pickup roller 731. The separation unit 732 has a separation roller on the upper side and a separation pad on the lower side, and separates a plurality of documents 74 from the uppermost sheet one by one. The separated document 74 is conveyed by the second registration roller 734 and the first conveyance roller 735 from the first registration roller 733 after the skew correction generated during the separation conveyance is performed by the first registration roller 733. Further, the separated document 74 passes through the flow reading position, and is sequentially turned from the second conveyance roller 736 to the third conveyance roller 737 and the discharge roller 738 with the document surface facing down on the discharge tray 73. Discharged. A platen guide 71 including a white sheet 71a is provided between the first conveyance roller 735 and the second conveyance roller 736, and presses the document 74 with a flat surface.

  As is apparent from the drawing, the platen guide 71 including the white sheet 71a and the white reference plate 12 each have a first position and a first position on the conveyance path of the document 74 facing the reading unit 13 through the reading glass. 2 is provided. The platen guide 71 at the first position is disposed on the upstream side of the conveyance path of the document 74 with respect to the white reference plate 12 at the second position. Further, the home position (standby position: HPS) of the reading unit 13 is set between the position immediately below the center of the white reference plate 12 and the flow reading glass 15, but the present invention is not limited to this. Depending on the application and purpose, the home position (standby position: HPS) of the reading unit 13 may be provided immediately below the white sheet 71a.

  On the scanner unit 1 side, the reading unit 13 is moved so as to read a predetermined position (reading position) of the flow reading glass 15, and the image on the original moved at a constant speed by the ADF unit 7 side is read. Note that a predetermined position on the flow reading glass 15 being read by the scanner unit 1 is referred to as a “flow reading position”.

  FIG. 2 is a block diagram showing a control configuration of the image reading apparatus.

  In the reading unit 13, the LED driving circuit (driver) 3 performs light amount adjustment of the illumination unit 131 for each line in the main scanning direction to control the lighting time of the LED, and reads an image on the document 74. The amplifier (AMP) 21 amplifies the electrical signal output from the reading unit 13, and the A / D conversion circuit 22 A / D converts the amplified electrical signal, for example, converts each color component of each pixel to 16 bits. A digital image signal expressed as a luminance value is output. A configuration necessary for A / D conversion including the A / D conversion circuit 22 is collectively referred to as a conversion unit.

  The illumination unit 131 is composed of RGB LEDs 1311 to 1313. Under the control of the CPU 5, the LED drive circuit 3 operates based on the timing signal generated by the timing generation circuit 4, and thus the LEDs 1311 to 1313 are operated. Lighting is controlled.

  The image processing unit 6 performs image processing on the digital image signal converted by the A / D conversion circuit 22. This image processing includes various processes necessary for image reading, including shading correction processing. The memory 61 stores image data obtained by image processing, and transfers an image by connecting to an interface with a printer that employs an inkjet method or an electrophotographic method, or an external device. The adjustment unit 62 adjusts the flow reading position that is the reading position based on the image data obtained by the image processing.

  The motor drive circuit 91 can rotate the scanner motor 18 according to the setting of the CPU 5 and can move the reading unit 13 at a constant speed. The motor driving circuit 92 rotates the ADF motor 75 according to the setting of the CPU 5 and conveys the document 74 placed on the ADF unit 7. The ADF document detection sensor 76 can detect that the document 74 is placed on the document tray 72 in a state where it can be read by the flow reading method.

  The CPU 5 can control the operation of various components of the image reading apparatus by reading a program stored in the ROM 52 and executing the program on the RAM 51. Various operations and settings for the image reading apparatus are performed via the operation unit 77. The operation unit 77 includes, for example, a display unit (liquid crystal display, LED, etc.), an instruction unit (button, touch panel), and the like, and performs various operations such as a reading instruction, setting the number of copies, specifying a read original size, and scaling. Can do.

  FIG. 3 is a partially enlarged view of the periphery of the platen guide 71 of the image reading apparatus.

  A white reference plate 12 (also referred to as a shading plate) is disposed in front of the platen guide 71 for adjusting the amount of light (shading) of the illumination unit 131 of the reading unit 13 when adjusting the flow reading position. Further, before and after the flow reading glass 15 for reading the document 74, a streak countermeasure sheet 71b that scrapes foreign matter (dust) on the surface of the document 74 conveyed by the ADF unit 7 and the document 74 are conveyed to the discharge tray 73. Therefore, a jump table 71c for guiding the document 74 from the flow-reading glass 15 to the conveyance path is provided.

  Above the flow reading glass 15, a platen guide 71 is disposed on the flow reading glass 15 so as to be pressed against the flow reading glass 15 so that the document 74 being conveyed does not flutter. The platen guide 71 is provided with a white sheet 71a, which is a white member, on the surface thereof so that the background of the document 74 read by flow reading becomes white.

  In the present embodiment, a configuration for adjusting an appropriate flow reading position based on a read image including an image corresponding to a predetermined portion (background body portion) of the white sheet 71a and the platen guide 71 will be described.

  FIG. 4 is a luminance value distribution of an image (background image) acquired for adjusting the reading position. The adjustment of the flow reading position is performed, for example, by setting a predetermined width (for example, 2 mm width) at the center of the main scanning at the time of the flow reading from a center of the platen guide 71 to a predetermined range (for example, 4 mm range) downstream of the flow reading. The luminance value of the background image is acquired by reading (for example, 0.1 mm).

  At this time, since adjustment of the flow reading position is performed with the ADF unit 7 closed without conveying the original 74, the white sheet 71a and the image of the sheet metal portion of the platen guide 71 are included via the flow reading glass 15. The image will be read. Then, the luminance values of the acquired images for one main scanning line are averaged, and a luminance value distribution as shown in FIG. 4 is acquired. From the luminance value distribution obtained at this time, the MAX value and the MIN value of the luminance value are detected, and the luminance value is converted into a ratio at a predetermined interval (for example, 0.1 mm interval) of sub-scanning (= luminance value / (MAX Value−MIN value) × 100). Then, the point below 80% after the rate conversion is determined as the edge (end portion) of the sheet metal part of the white sheet 71a and the platen guide 71, and a point at a predetermined distance from the edge is set as the reading position, and the position Information is stored in the RAM 51.

  Here, FIG. 5 is a luminance value distribution of a read image (a read image including an image corresponding to a predetermined portion (background body portion) of the white sheet 71a and the platen guide 71) at the time of adjusting the flow reading position in a normal state. . Here, the normal state is a state in which the ADF unit 7 is closed during the adjustment of the flow reading position.

  On the other hand, FIG. 6A shows the luminance value distribution of the read image in an abnormal state such as when the ADF unit 7 is opened during adjustment of the flow reading position. FIG. 6B is a luminance value distribution of the read image in an abnormal state such as when the flow reading position is adjusted while the ADF unit 7 is opened.

  In the present embodiment, an abnormal state as shown in FIGS. 6A and 6B is determined using a threshold value. When the ADF unit 7 is opened, the reflected light from the white sheet 71a and the platen guide 71 is not incident on the imaging unit 134 of the reading unit 13, so that the acquired luminance value is lowered. Therefore, when the acquired luminance value is equal to or less than the first threshold value (predetermined luminance value) and the interval of the luminance value equal to or less than the first threshold exists (continuous) above a certain interval (second threshold value), the ADF unit 7 Abnormal information is generated on the assumption that the reading position has not been adjusted normally while being opened. Thus, in this embodiment, the state (open state) of the ADF unit 7 is determined based on the read image of the background body portion.

  FIG. 7 is a flowchart showing an adjustment process related to adjustment of the flow reading position. The adjustment of the scanning reading position is mainly performed at the initial setting at the time of shipment of the ADF unit 7 or at the time of market exchange, but may be performed at the time of starting the scanning reading job instructing the reading of the original by the scanning reading. Note that the flowchart shown in FIG. 7 is realized by the CPU 5 reading a program stored in the ROM 52 and executing it on the RAM 51.

  First, when the start button is pressed on the operation unit 77, the CPU 5 moves the reading unit 13 to the edge search start position (FIG. 3) (S101). The edge search start position is set at a predetermined distance from the HPS (FIG. 3) to the flow reading glass 15 side.

  The CPU 5 irradiates the background portion with light from the edge search start position toward the HPS by the reading unit 13 and photoelectrically converts the reflected light to obtain a luminance value (S102). At that time, the CPU 5 acquires the luminance value of the background body (platen guide 71) for the background portion of 4.0 mm in the sub-scanning direction at a predetermined interval (for example, 0.1 mm interval) while moving the reading unit 13. (S103). The CPU 5 calculates the average value of the luminance values for the central 64 pixels in the main scanning direction for each line for every 0.1 mm in the sub-scanning direction by the adjusting unit 62 (S104).

  The CPU 5 determines whether there is a luminance value equal to or less than a preset threshold value 1 (first threshold value) among the calculated luminance values (S105). Here, the threshold value 1 needs to be set higher than the luminance value acquired when the ADF unit 7 is opened. This is because if the value of the threshold 1 is too low, it cannot be determined that the ADF unit has been opened, and the flow reading position adjustment may not be performed normally. On the other hand, if the value of the threshold value 1 is too high, it may be erroneously determined that the ADF unit 7 is opened even if the ADF unit 7 is not opened. Therefore, an appropriate threshold value 1 obtained empirically according to the installation environment state may be set. In the example of FIG. 6, the threshold 1 is set to the luminance 50.

  As a result of the determination, if there is a luminance value equal to or less than the threshold value 1 (YES in S105), the CPU 5 counts pixels in which the luminance value equal to or less than the threshold value 1 continues, and the interval of the luminance value equal to or less than the threshold value 1 is set in advance. It is determined whether the threshold value 2 (second threshold value) or more is continued (S106). That is, the CPU 5 counts how many pixels the luminance value that becomes the threshold value 1 or less is continuously present. Further, for example, when the luminance value of the next pixel is larger than the threshold value 1 for a pixel having a luminance value equal to or less than the threshold value 1, the pixel count is returned to zero. Note that the threshold value 2 is, for example, a distance that is ½ of the sub-scanning direction that is acquired by adjusting the scanning reading position. In the example of FIG. 6, the threshold value 2 is set to 2 mm.

  When the section where the luminance value is equal to or less than the threshold value 1 and the pixels having the luminance value equal to or less than the threshold value 1 is equal to or greater than the threshold value 2 (section) (YES in S106), the CPU 5 determines that the ADF unit 7 is determined to be open or open for a certain period of time. Therefore, in this case, the CPU 5 outputs the adjustment NG to the operation unit 77 (S107). This prompts the user or operator to adjust the flow reading position again. For example, in this case, the operation unit 77 displays again an adjustment screen including an operation button for instructing execution of adjustment of the reading position.

  On the other hand, when the luminance value is larger than the threshold value 1 (NO in S105), or when the luminance value is equal to or smaller than the threshold value 1 but the interval of pixels having luminance values equal to or smaller than the threshold value 1 is smaller than the threshold value 2 ( In S106, the CPU 5 obtains the maximum luminance value and the minimum luminance value from the average value of the luminance values calculated in S104 by the adjustment unit 62. Then, a relative luminance value of 4.0 mm in the sub-scanning direction is calculated from the acquired luminance value by (Equation 1).

Relative luminance value = luminance value / (maximum luminance value−minimum luminance value) × 100 (Equation 1)
The calculated luminance value distribution is, for example, as shown in FIG.

  Then, the CPU 5 detects a point where the relative luminance value is 80% as an edge of the white sheet 71a of the platen guide 71 (S110). The CPU 5 determines a predetermined position (for example, a position of 3.32 mm) upstream from the detected edge as a flow reading position, and stores the position information in the RAM 51 (S111).

  Thus, by detecting the state of the ADF unit 7 using the threshold value 1 and the threshold value 2, even when the ADF unit 7 is opened during the reading position adjustment, the decrease in the luminance value at that time is reduced in the white sheet 71a. It is possible to prevent erroneous detection as an edge.

  Next, an example of an image reading operation using the ADF unit 7 will be described with reference to FIG. The flowchart shown in FIG. 9 is realized by the CPU 5 reading a program stored in the ROM 52 and executing it on the RAM 51.

  First, when detecting that the start button (copy button) is pressed in the operation unit 77, the CPU 5 sets the flow reading position by adjusting the flow reading position shown in FIG. 7 (S201). Next, the CPU 5 acquires various correction values such as the shading correction value acquired by the image processing unit 6 (S202). Thereafter, the CPU 5 moves the reading unit 13 to the reading position (flow reading position) set on the flow reading glass 15 (S203).

  The CPU 5 reads the original conveyed on the flow reading glass 15 by the reading unit 13 and corrects the read image using the various correction values acquired in step S202 for the image obtained by the reading (S204). After completion of reading, the CPU 5 determines whether or not there is a next original (S205). If there is a next original (YES in S205), the process returns to S204, and a series of operations are repeated on the next original again. On the other hand, if there is no next original (NO in S205), the process is terminated.

  As described above, according to the present embodiment, it is possible to prevent the ADF unit from being opened and closed during the adjustment of the flow reading position and erroneously detecting the edge of the platen guide for determining the flow reading position. it can. Further, by preventing this erroneous detection, it is possible to prevent image degradation caused by the shift reading position deviating from an appropriate position.

  In addition, the function of the above embodiment is realizable also with the following structures. That is, it is also achieved by supplying a program code for performing the processing of the present embodiment to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus executing the program code. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code also realizes the function of the present embodiment.

  Further, the program code for realizing the function of the present embodiment may be executed by one computer (CPU, MPU), or may be executed by a plurality of computers cooperating. Also good. Further, the program code may be executed by a computer, or hardware such as a circuit for realizing the function of the program code may be provided. Alternatively, a part of the program code may be realized by hardware and the remaining part may be executed by a computer. Further, the CPU is not limited to the one that performs all the processing by one CPU, and a plurality of CPUs may perform the processing while appropriately cooperating.

  12: White reference plate, 13: Reading unit, 133: Optical lens, 134: Imaging unit, 15: Flow reading glass, 21: Amplifier, 22: A / D conversion circuit, 3: LED drive circuit, 4: Timing generation circuit 5: CPU, 6: Image processing unit, 61: Memory, 62: Adjustment unit, 621: Sub-scanning average processing unit, 622: High-pass filter, 623: Image determination unit, 7: ADF unit, 71: White reading roller, 72: Document tray, 731: Pickup roller, 732: Separation unit, 733: First registration roller, 734: Second registration roller, 735: First conveyance roller, 736: Second conveyance roller, 737: Third conveyance roller, 738: Paper discharge roller, 74: Document, 75: ADF motor, 76: ADF document detection sensor, 77: Operation unit

Claims (7)

Reading means capable of reading an image of a document on a reading position;
A conveying means provided so as to be openable and closable with respect to the reading position, and conveying the document to the reading position;
Detecting means for detecting the reading position based on a reading result by the reading means in a state where the original is not conveyed by the conveying means;
Determining means for determining whether or not the detection means can detect the reading position based on a read image by the reading means in a state in which the original is not conveyed by the conveying means;
The image reading apparatus, wherein the detection unit detects the reading position when it is determined by the determination unit that the detection unit can detect the reading position. The determination unit determines that the conveyance unit is in an abnormal state when the interval of pixels having a luminance value equal to or lower than the first threshold value among the luminance values of the pixels constituting the read image by the reading unit continues for the second threshold value or more. The image reading apparatus according to claim 1, wherein the image reading apparatus is determined to be. When it is determined that the state of the transport unit is abnormal as a result of the determination by the determination unit, the display unit further includes a display unit that displays an adjustment screen for adjusting the reading position of the reading unit again. The image reading apparatus according to any one of claims 1 and 2. When the determination unit determines that the detection unit can detect the reading position, the detection unit has a maximum luminance value and a minimum luminance value among the reading results of the reading unit. The image reading apparatus according to claim 1, wherein the reading position is detected based on a relative luminance value calculated based on the image quality. An image reading apparatus according to any one of claims 1 to 4,
Image forming means for forming an image on a recording medium based on an image read by the image reading device;
An image forming apparatus comprising: A control method for an image reading apparatus, comprising: a reading unit capable of reading an image of a document on a reading position; and a transport unit provided so as to be openable and closable with respect to the reading position and transporting the document to the reading position. ,
A detection step of detecting the reading position based on a reading result by the reading unit in a state where the document is not conveyed by the conveying unit;
A determination step for determining whether or not the detection of the reading position by the detection step can be performed based on an image read by the reading unit in a state where the original is not conveyed by the conveyance unit,
The image reading apparatus according to claim 1, wherein the detecting step detects the reading position when it is determined by the determining step that the reading position can be detected by the detecting step.
An image reading apparatus control method comprising: An image reading apparatus including a reading unit that can read an image of a document on a reading position, and a conveyance unit that can be opened and closed with respect to the reading position and that conveys the document to the reading position functions as a computer. A program for
The computer,
Detecting means for detecting the reading position based on a reading result by the reading unit in a state where the document is not conveyed by the conveying unit;
Functioning as a determination unit that determines whether the detection unit can detect the reading position based on an image read by the reading unit in a state where the document is not conveyed by the conveyance unit;
The said detection means detects the said reading position, when it determines with the said detection means being able to detect the said reading position by the said determination means. The program characterized by the above-mentioned.