JP2010062924A - Image reading apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus and a program capable of detecting at least either whether an original is rapidly and accurately tilted as compared with a method wherein an original is read and the tilt is detected by using one line sensor, or a degree of the tilt. <P>SOLUTION: When an original carried to an original reading position is read by a plurality of reading parts for reading each of a plurality of pixel columns spaced as prescribed along a scan direction which intersects the line direction in a plurality of different pixel columns along a line direction, positions (E11 to E23) of an edge of an original carried to the original reading position are detected based on an image signal for each of pixel columns (L1 to L3) read by each of the plurality of reading parts. At least either whether the original carried to the original reading position inclines, or its tilting degree is detected based on each of the detected positions (E11 to E23) of the edge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and a program.

  In an image reading apparatus that reads a document by transporting the document to a reading position by a document feeder, the document may be transported obliquely and read.

As a technique related to image reading, there is known an image reading apparatus that reads an original using a single line sensor and detects the inclination of the original based on the reading result. For example, an image reading apparatus that stores image data read by a single line sensor in a memory as multi-value data and detects and corrects an inclination is known (for example, see Patent Document 1). Also, for example, an image reading apparatus that reads an image of a document while conveying the document, detects the tilt of the document based on the read image data and the transport speed of the document, and corrects the tilt according to the detected tilt is also known. (For example, refer to Patent Document 2).
JP 2002-142084 A JP 2001-358914 A

  The present invention provides an image reading apparatus capable of detecting whether or not a document is tilted at high speed and accurately and at least one of the degree of tilt as compared with a case where a document is read and tilt detected using a single line sensor. And to provide a program.

  An image reading apparatus according to a first aspect of the present invention includes a conveying unit that conveys a document to a document reading position, and a plurality of different pixel rows along a first direction, and a second crossing the first direction. A plurality of reading sections for respectively reading a plurality of pixel rows separated by a predetermined interval along the direction of the document, a document reading means for reading the document conveyed to the document reading position, and the plurality of reading sections Each of the edge detection means for detecting the position of the edge of the document conveyed to the document reading position on the basis of the image signal for each pixel row read by each of the image data, and each of the edge positions detected by the edge detection means. And an inclination detecting means for detecting at least one of whether the original conveyed to the original reading position is inclined and the degree of inclination.

  According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the edge detection unit detects the positions of two edges for each pixel row read by the plurality of reading units, and the inclination detection unit. Each of the positions of the edges closer to the predetermined reference position in the first direction, and the positions of the other edges, of the two edges for each pixel row detected by the edge detection means, Whether or not the document conveyed to the document reading position is tilted and at least one of the degree of tilt is detected based on at least one of the above.

  According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, the edge detecting unit detects the positions of two edges for each pixel row read by the plurality of reading units, and detects the inclination. The means sets the original reading position based on each of the positions of the edges closer to the predetermined reference position in the first direction among the two edges for each pixel row detected by the edge detecting means. At least one of whether or not the conveyed document is inclined and the degree of inclination is detected.

  According to a fourth aspect of the present invention, in the image reading apparatus according to the first aspect, the edge detecting unit detects the positions of two edges for each pixel row read by the plurality of reading units, and detects the inclination. The means determines whether or not each of the edge positions closer to a predetermined reference position among the two edges for each pixel column detected by the edge detection means is an edge position detected from the same side. , And whether each of the other edge positions is an edge position detected from the same side, and each of the edge positions determined to be the edge positions detected from the same side Based on the above, it is detected whether or not the original conveyed to the original reading position is inclined and at least one of the degree of inclination.

  According to a fifth aspect of the present invention, in the image reading apparatus according to the first aspect, the edge detecting unit detects the positions of two edges for each pixel row read by the plurality of reading units, and detects the inclination. The means sets the document reading position based on each of the positions of the edges closer to the predetermined reference position in the first direction among the two edges for each pixel row detected by the edge detecting means. Whether or not the conveyed document is tilted and whether or not the document transported to the document reading position is tilted based on each of the first detection process for detecting at least one of the degree of tilt and the position of the other edge And a second detection process for detecting at least one of the degree of inclination, and when the detection results of the first detection process and the second detection process are different, a predetermined edge position is set. Detection result of detection process performed based on To select.

  According to a sixth aspect of the present invention, in the image reading apparatus according to the first aspect, the edge detecting unit detects the positions of two edges for each pixel row read by the plurality of reading units, and detects the inclination. When detecting the degree of inclination, the means detects the position of the edge closer to the predetermined reference position in the first direction among the two edges for each pixel column detected by the edge detection means. A first detection process for detecting the degree of inclination based on each of the first and a second detection process for detecting at least one of the degrees of inclination based on each of the positions of the other edge, and When the detection results of the process and the second detection process are different, the detection result with the smaller degree of inclination is selected.

  According to a seventh aspect of the present invention, in the image reading apparatus according to any one of the first to sixth aspects, when the degree of inclination is detected by the inclination detecting means, the inclination detecting means detects the inclination. The image processing apparatus further includes correction means for correcting the reading result of the original when the value indicating the degree of inclination is equal to or greater than a predetermined threshold.

  According to an eighth aspect of the present invention, there is provided a program for causing a computer to function as an edge detecting means and an inclination detecting means constituting the image reading apparatus according to any one of the first to seventh aspects.

  According to the ninth aspect of the present invention, the computer is a plurality of different pixel columns along the first direction, and is spaced apart by a predetermined interval along the second direction intersecting the first direction. An image signal for each pixel column that is read by each of the plurality of reading units of the document reading unit that includes a plurality of reading units for reading each of the plurality of pixel columns and reads the document conveyed to the document reading position by the conveying unit. Based on the edge detection means for detecting the position of the edge of the document conveyed to the document reading position, and on the basis of each of the edge positions detected by the edge detection means, This is a program for functioning as an inclination detecting means for detecting at least one of whether or not an original is inclined and the degree of inclination.

  According to the first aspect of the present invention, it is possible to detect at least one of whether or not the document is inclined at a higher speed and more accurately than when the document is read and detected by using one line sensor. can do.

  According to the second aspect of the present invention, it is possible to detect at least one of whether or not the document is inclined more accurately and the degree of inclination of the document.

  According to the invention of claim 3, it is possible to detect at least one of whether or not the document is inclined at a higher speed and the degree of inclination of the document.

  According to the fourth aspect of the present invention, it is possible to detect at least one of whether or not the document is tilted more accurately and the degree of tilt of the document.

  According to the fifth aspect of the present invention, it is possible to detect at least one of whether or not the original is inclined and the degree of inclination of the original more efficiently by predetermining the selection side in advance.

  According to the invention of claim 6, for example, when correction is performed according to the detected degree of inclination, it is possible to prevent overcorrection.

  According to the seventh aspect of the present invention, it is possible to prevent correction when the inclination is such that correction is not necessary.

  According to the eighth aspect of the present invention, it is possible to detect at least one of whether or not the document is tilted at high speed and more accurately and the degree of tilt of the document compared to the case where the document is read and detected using a single line sensor. can do.

  According to the ninth aspect of the present invention, it is possible to detect at least one of whether or not the document is inclined at a higher speed and more accurately than when the document is read and detected by using one line sensor. can do.

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

  FIG. 1 is a block diagram showing a schematic configuration of an image reading apparatus 10 according to an embodiment of the present invention. The image reading apparatus 10 includes a CPU (Central Processing Unit) 12, a RAM (Randam Access Memory) 14, a ROM (Read Only Memory) 16, an I / O (input / output) interface 18, and a communication interface 20. Are connected to each other.

  A CD-ROM drive 24, an FD (flexible disk) drive 28, and an HDD (hard disk drive) 32 are connected to the I / O interface 18. The CD-ROM drive 24 reads data from a CD-ROM 26 that is a portable recording medium. The FD drive 28 reads and writes data from and to the FD 30 that is a portable recording medium. The HDD 32 reads and writes data from and to the built-in hard disk.

  Further, the I / O interface 18 includes a keyboard 34 for inputting various information by a user's operation, a display 38 for displaying information such as an image in response to an instruction from the CPU 12, and an image displayed on the display 38. A pointing device 36 for inputting an instruction by designating an arbitrary position is connected. Here, the keyboard 34 and the pointing device 36 are provided as input devices. However, if the display 38 is a touch panel display, the display 38 may be used as an input device. It is not limited to the pointing device 36.

  The I / O interface 18 is connected to a scanner 40 that reads an image of a document. The CPU 12 instructs the scanner 40 to read an image of a document via the I / O interface 18, acquires image data read by the scanner 40, and stores it in the RAM 14.

  The communication interface 20 is connected to a network such as a communication line or a LAN. The image reading apparatus 10 exchanges information with other terminals connected to the network via the communication interface 20.

  The CPU 12 executes a program (including an inclination detection processing program described later) stored in the ROM 16, the HDD 32, or the like. The RAM 14 is a frame memory for temporarily storing various image data such as image data input from other terminals via the communication interface 20, image data input from the scanner 40, newly generated image data, and the like. In addition to being used, it is also used as a work memory during program execution.

  Note that the recording medium on which the program executed by the CPU 12 is stored is not limited to the ROM 16 or the HDD 32, but may be the CD-ROM drive 24 or the FD drive 28. It may be a portable recording medium such as a disk, a magneto-optical disk, an IC card, a storage device such as an HDD provided outside the image reading apparatus 10, and a database connected via a network, or the like. It may be a transmission medium such as a computer system and its database, or a carrier wave on a telecommunication line.

  FIG. 2 is a configuration diagram of the scanner 40. The scanner 40 includes a document feeding unit 50 that sequentially conveys a document and a document reading unit 60 that reads an image of the document.

  The upper document feed section 50 is provided with a document placement section (not shown) and a retard roll (not shown) for placing (setting) a document to be read. The originals set in the original placement unit are fed one by one by a retard roll and conveyed into the original feeding unit 50.

  Further, the original feeding section 50 includes a conveying roll 42 that conveys the originals that are fed one by one along the original conveying path A to a downstream roll, and an original reading position where the platen glass 70 is installed. A conveyance roll 44 for conveying the document, an assist plate 46 for assisting document conveyance to the document reading position, and a conveyance roll 48 for conveying the document conveyed to the document reading position further downstream are provided. A portion sandwiched between the platen glass 70 and the assist plate 46 is a document reading position.

  The lower document reading unit 60 reads an image of the document conveyed by the upper document feeding unit 50.

  The document reading unit 60 includes a platen glass 70, a full rate carriage 73 for reading an image of the document from below the platen glass 70, and a half rate carriage 75 that provides light obtained from the full rate carriage 73 to the imaging lens 77. And.

  The full-rate carriage 73 includes an illumination lamp 72 that irradiates light on the document, a mirror 74 that reflects the light emitted from the illumination lamp 72 toward the document surface, and a mirror 76A that receives reflected light obtained from the document. Yes.

  The half-rate carriage 75 includes a mirror 76B and a mirror 76C that provide light obtained from the mirror 76A to the imaging lens 77.

  Further, the document reading unit 60 optically reduces the optical image obtained from the mirror 76C, and a CCD (Charge Coupled Device) that photoelectrically converts the optical image formed by the imaging lens 77. An image sensor 78 is provided. An image signal obtained by the CCD image sensor 78 is sent to the CPU 12 via a drive substrate (not shown).

  When the scanner 40 reads a document placed on the platen glass 70, first, the full rate carriage 73 and the half rate carriage 75 move in the scanning direction (arrow B direction) at a ratio of 2: 1. Then, the light of the illumination lamp 72 of the full-rate carriage 73 is irradiated on the surface to be read of the document, and the reflected light from the document is reflected in the order of the mirror 76A, the mirror 76B, and the mirror 76C to the imaging lens 77. Led. When the reading of one line is completed by each of the line sensors 80, the full rate carriage 73 is moved in the direction of arrow B to read the next line of the document. By executing this over the entire document size, reading of one page of the document is completed.

  When reading a document placed on the document placement unit, the full-rate carriage 73 is moved to a position below the document reading position and stopped to move the reading optical system mounted on the full-rate carriage 73 below the document reading position. In the stopped state, when the original conveyed by the original feeding section 50 passes through the original reading position, the reflected light from the original passing (moving) is guided to the imaging lens 77.

  The light guided to the imaging lens 77 is received by the CCD image sensor 78 and imaged. The CCD image sensor 78 according to the present embodiment includes three different pixel rows along a direction intersecting the scan direction (hereinafter referred to as a line direction), and is separated by a predetermined interval along the scan direction. Three line sensors 80a, 80b, and 80c for reading one pixel column are provided. In addition, when it demonstrates without distinguishing each of each line sensor 80a, 80b, 80c, the code | symbol at the end is abbreviate | omitted and it calls the line sensor 80.

  Each of the line sensors 80 is a one-dimensional sensor in which a plurality of light receiving elements are arranged, and processes one pixel column in the line direction collectively. Specifically, each light receiving element outputs an analog image signal corresponding to incident light. The analog image signal is converted into a digital image signal by an analog-digital converter (not shown), and stored in a storage unit such as the RAM 14 or the HDD 32 via the I / O interface 18. Hereinafter, one pixel column read by one line sensor 80 is referred to as one line.

  Hereinafter, an image reading process performed by the image reading apparatus 10 according to the present embodiment will be described. In the present embodiment, the description is limited to a case where a document to be read is a general fixed-size document (a document generated so that four corners are squares with right angles).

  First, the user presses a start button for reading a document in a state in which the document is set on a document placing unit provided in the document feeding unit 50 of the scanner 40. Specifically, the CPU 12 displays a start button on the display 38 and allows the user to select with the pointing device 36 (when the display 38 is a touch panel display, contact selection with a finger or the like). Alternatively, the image reading apparatus 10 may be provided with a start button, and the start button may be pressed. When the user selects (presses) the start button, the process shown in FIG. 3 is started.

  FIG. 3 is a flowchart illustrating an example of a flow of an inclination detection processing program at the time of image reading executed by the CPU 12.

  In step 100, the CPU 12 transmits a control signal for starting the document conveyance to the scanner 40, and controls the document set on the document placing unit to be conveyed to the document reading position.

  In step 102, when the document is conveyed to the document reading position, the CPU 12 transmits a control signal for reading the document to the scanner 40, and causes the three line sensors 80 to read the document. The image signal of each line obtained by reading is stored in a predetermined storage means (for example, the RAM 14 or the HDD 32).

  In step 104, the CPU 12 reads out the image signal obtained by reading in step 102 from the storage means, and performs edge detection processing. The edge detection process uses a generally known technique such as detecting a portion where an image signal is rapidly changed by image processing as an edge of the document. Further, here, edge detection processing is performed based on the image signals of the three lines read by the three line sensors 80 when a predetermined time has elapsed since the original reached the original reading position. .

  In step 106, the CPU 12 determines the inclination of the document based on the edge position detected from the image signal of each line read by the plurality of line sensors 80.

  FIG. 4 is an explanatory diagram for explaining an example of an inclination detection process performed based on the reading results of the three line sensors 80. As shown in FIG. 4, the three line sensors 80 read the image of the lines indicated by L1 to L3 of the document.

  The positions of the edges on the line L1 (hereinafter referred to as edge positions) detected based on the image signal of the line L1 are E11 and E21, and the edge positions on the line L2 detected based on the image signal of the line L2 are E12. , E22, and the edge positions on the line L3 detected based on the image signal of the line L3 are E13, E23.

  In the present embodiment, a predetermined position in the line direction is set as the reference position. Although there may be one reference position, in the present embodiment, two reference positions are set.

  Further, when the user sets the document on the document placement unit, the user usually sets the document by contacting one side of the document with a positioning guide (not shown) provided on the document placement unit. Hereinafter, the side on which the document is abutted is referred to as a registration side, and the reverse side is referred to as a reverse registration side. In FIG. 4, the upper side is the cash register side, and the lower side is the reverse cash register side. The registration-side reference position is referred to as a registration-side reference position Q1, and the reverse registration-side reference position is referred to as a reverse registration-side reference position Q2.

  The document is transported within a range from the registration-side reference position Q1 to the reverse registration-side reference position Q2, and each line sensor 80 receives light in a range from at least the registration-side reference position Q1 to the reverse registration-side reference position Q2. Is configured to be possible.

  In step 106, first, the CPU 12 obtains distances X11, X12, and X13 between the registration-side edge positions E11, E12, and E13 and the registration-side reference position Q1. Further, the CPU 12 obtains distances X21, X22, and X23 between the reverse registration side edge positions E21, E22, and E23 and the reverse registration side reference position Q2.

  Next, the CPU 12 compares the obtained distances to determine whether or not the document is tilted. Specifically, when X11 = X12 = X13 and X21 = X22 = X23, it is determined that the document is not inclined. Further, the CPU 12 determines that the document is inclined when X11 = X12 = X13 is not satisfied and X21 = X22 = X23 is not satisfied. In the example shown in FIG. 4, since X11 ≠ X13 and X21 ≠ X23, it is determined that the document is tilted.

  In consideration of the reading error of each line sensor 80, etc., even if the distances do not completely match, if the error is within a predetermined range, it is determined that the document is not inclined. Also good.

  In this example, it is determined whether the document is inclined by using both the edge position on the registration side and the edge position on the reverse registration side. However, the edge position on the registration side and the edge position on the reverse registration side are determined. Either one of the above may be used to determine whether the document is tilted.

  If it is determined in step 106 that the document is tilted, the process proceeds to step 108.

  In step 108, the CPU 12 calculates a tilt angle θ that indicates how much the document is tilted using either the registration-side edge position or the reverse registration-side edge position. The CPU 12 uses the distance (XA, XB) between the two edge positions and the reference position among the edge positions on the side that each edge position is determined to be located on the same straight line, as shown in the following equation (1). To do.

^{θ = tan -1 ((XA-} XB) / N) ··· (1)

  In the equation (1), N indicates the distance in the scanning direction between the two edge positions (the interval between the scanning positions in the scanning direction of the line sensors 80 that read the two edges).

In the example shown in FIG. 4, it is determined that the registration-side edge positions E11, E12, E13 detected from the same side are located on the same straight line. Therefore, the CPU 12 uses the distance between two edge positions among the edge positions E11, E12, and E13 and the registration-side reference position Q1 to calculate according to the above equation (1). For example, when calculated using the X11 and X13, is calculated as ^{θ = tan -1 ((X11-} X13) / N).

  For example, in the case where the scanning line interval in the scanning direction of the CCD image sensor 28 is 10 lines, when it is detected that one pixel original is displaced by 10 lines, the inclination angle of the original is about 5.7 degrees. Become.

  As shown in FIG. 4, for the edge positions on the reverse registration side, the edge positions E21, E22, E23 are not on the same straight line. This is because the sides where E22 and E23 are detected are different from the sides where E21 is detected. Therefore, the combination of E22 and E23 can obtain the document inclination angle θ, but the combination of E21 and E22 detected at different sides or the combination of E21 and E23 cannot obtain the document inclination angle θ. As a result, in the present embodiment, the calculation is performed using the distance between the edge position on the registration side determined to be located on the same straight line (detected from the same side) and the reference position. I have to.

  Here, it is determined whether or not each edge position is detected from the same side by determining whether or not each edge position is located on the same straight line, and the edge position on the side determined to be detected from the same side The example in which the tilt angle is calculated using the distance from the reference position has been described. However, in consideration of the reading error of each line sensor 80 and the like, a predetermined range may be used even if they are not completely located on the same straight line. May be determined as being detected from the same side.

  If it is determined that each of the edge positions on the registration side is on the same straight line and each of the edge positions on the reverse registration side is on the same straight line, either may be used for calculation.

  In step 110, the CPU 12 determines whether or not the obtained inclination angle θ exceeds a preset threshold value. When the CPU 12 determines that the obtained inclination angle θ exceeds a preset threshold value, the CPU 12 performs inclination correction in step 112. For example, the image data obtained by reading the document is subjected to correction such as a rotation process for rotating the image by the obtained inclination angle θ.

  On the other hand, if the CPU 12 determines in step 110 that the obtained tilt angle θ does not exceed the preset threshold value, the CPU 12 ends without performing the process of step 112.

  The present invention is not limited to the above-described embodiment, and various design changes may be made within the scope of the invention described in the claims. Hereinafter, various modifications will be described.

  (Modification 1)

  In the above-described embodiment, the inclination angle θ is obtained as data indicating how much the document is inclined. However, the data is not limited to the inclination angle θ as long as the data indicates the degree of inclination. For example, tan θ may be obtained as data indicating the degree of inclination.

  Further, when the inclination angle θ is obtained, it is obtained by using the equation (1). However, a table in which the edge position and the inclination angle are associated with each other is generated in advance and stored in a storage unit such as the HDD 32. You may make it leave. In this case, the CPU 12 obtains the inclination angle θ with reference to the table.

  (Modification 2)

  In the above embodiment, the distances X11, X12, and X13 between the registration-side edge positions E11, E12, and E13 and the registration-side reference position Q1 are obtained, and the reverse registration-side edge positions E21, E22, and E23 are obtained. The distances X21, X22, and X23 with respect to the reverse registration side reference position Q2 are obtained, the magnitudes of the distances are compared, it is determined whether or not the document is tilted, and the tilt angle θ is determined when it is determined that the document is tilted. An example was described. However, the present invention is not limited to this. For example, without determining whether or not the vehicle is tilted, the tilt angle θ is first obtained and whether or not the tilt angle θ is tilted or whether or not to be corrected. You may make it judge.

  (Modification 3)

  In the above-described embodiment, the example in which the tilt correction is performed when the tilt angle θ exceeds a preset threshold has been described. However, the tilt or the tilt angle θ can be determined by the user without performing the tilt correction. You may make it alert | report. Even if the tilt angle θ does not exceed a preset threshold value, the user may be notified of the tilt angle θ and make the user determine whether to correct or read again. Further, the inclination correction may be performed uniformly regardless of the inclination angle θ.

  The determination result of step 106 (whether or not it is tilted) may be notified to the user, and the calculation of the tilt angle θ and the tilt correction in steps 108 to 110 may not be performed.

  (Modification 4)

  Moreover, although the example using the three line sensors 80 was demonstrated in the said embodiment, the structure using two or more line sensors should just be sufficient, for example, two may be sufficient and four may be sufficient. In addition, when using two line sensors, you may make it detect inclination as follows.

  Here, an example of an inclination detection process when two line sensors 80 are used will be described with reference to FIGS. 3 and 5. FIG. 5 is an explanatory diagram for explaining an example of an inclination detection process performed based on the reading results of the two line sensors 80.

  Steps 100 to 102 are performed in the same manner as in the above embodiment.

  In step 104, the CPU 12 performs edge detection processing from the image signal obtained by reading in step 102. Here, the edge detection process is performed using the image signal of each line read when a predetermined time t1 and t2 have elapsed since the document reached the reading position.

  In FIG. 5, the lines read when the time t1 has elapsed are indicated by L1a and L2a, and the lines of the image signal read when the time t2 has elapsed are indicated by L1b and L2b.

  Further, the edge positions detected on the line L1a based on the image signal of the line L1a are E11a and E12a, and the edge positions detected on the line L2a based on the image signal of the line L2a are E12a and E22a. Further, the positions of the edges on the line L1b detected based on the image signal of the line L1b are E11b and E21b, and the positions of the edges on the line L2b detected based on the image signal of the line L2b are E12b and E22b. is there.

  In step 106, the CPU 12 detects from the image signals read by the two line sensors 80 when the time t1 elapses or the image signals read by the two line sensors 80 when the time t2 elapses. The inclination of the document is determined based on the edge position.

  When the edge positions of L1a and L2a are used, the CPU 12 calculates distances X11a and X12a between the registration-side edge positions E11a and E12a and the registration-side reference position Q1. Further, the CPU 12 obtains distances X21a and X22a between the reverse registration side edge positions E21a and E22a and the reverse registration side reference position Q2.

  The CPU 12 compares the obtained distances to determine whether or not the document is tilted. Specifically, when X11a = X12a and X21a = X22a, it is determined that the document is not inclined. The CPU 12 determines that the document is tilted when X11a = X12a is not satisfied and X21a = X22a is not satisfied. In the example shown in FIG. 5, since X11a ≠ X12a and X21a ≠ X22a, it is determined that the document is inclined.

  Here, it is determined whether or not the document is inclined by using both the edge position on the registration side and the edge position on the reverse registration side. However, the edge position on the registration side and the edge on the reverse registration side are determined. It may be determined whether or not the document is tilted using one of the positions.

  If it is determined in step 106 that the document is tilted, the process proceeds to step 108.

  In step 108, the CPU 12 calculates a tilt angle θ that indicates how much the document is tilted using either the registration-side edge position or the reverse registration-side edge position. Here, the CPU 12 compares the magnitude relationship of the distance between each of the read edge positions of each line and the reference position, and the distance becomes larger as the distance in the scanning direction upstream (or downstream), or The edge position (XA) detected from the image signal read when the time t1 elapses or the image signal read when the time t2 elapses. , XB) to calculate as in (1) above.

  For example, in the example shown in FIG. 5, the distance between each of the registration-side edge positions E11a, E12a, E11b, and E12b detected from the same side and the registration-side reference position Q1 is smaller as the distance on the upstream side in the scanning direction. (X11a> X12a> X11b> X12b). On the other hand, the distance between each of the edge positions E21a, E22a, E21b, E22b on the reverse registration side and the reference position Q2 on the reverse registration side is a relationship of X21a> X22a> X21b> X22b and a relationship of X21a <X22a <X21b <X22b. None of them are met. This is because the side where E21a is detected is different from the side where E22a, E21b and E22b are detected. Therefore, the CPU 12 calculates the tilt angle θ using the edge position on the registration side.

  When the distance between each edge position and the reference position is increased or decreased toward the upstream side (or downstream side) in the scanning direction on both the registration side and the reverse registration side. May be calculated using either.

  Since the processing from step 110 to step 112 is the same as that in the above embodiment, the description thereof is omitted.

  Even when two line sensors 80 are used, the determination result of step 106 (whether or not it is tilted) is notified to the user, and the tilt angle θ is calculated or corrected in steps 108 to 110. It is good also as a structure which does not perform etc.

  When the tilt angle θ is not calculated, edge detection is performed using the reading result read at one place (either when the time t1 has elapsed or when the time t2 has elapsed), and the tilt is detected. Detection may be performed. Further, even when the inclination angle θ is calculated, when it is assumed that the inclination angle θ is not so large, edge detection is performed using a reading result read at a predetermined location, and registration is performed. The inclination angle θ may be calculated using an edge position on a predetermined side of the side and the reverse registration side.

  (Modification 5)

  In the above embodiment and the first to fourth modifications, the description is limited to the case where the document to be read is a general fixed-size document (a document generated so that the four corners are squares with right angles). However, when the shape is a trapezoid or a triangle, the determination may be made in consideration of an irregular document.

  When considering a non-standard document, the following processing may be performed in step 106 described above.

  First, in step 106, when X11 = X12 = X13 and X21 = X22 = X23, the CPU 12 determines that the document is fixed and not tilted. Further, when X11 = X12 = X13 is not satisfied and X21 = X22 = X23 is not satisfied, the CPU 12 determines that the document is inclined or non-standard. If the CPU 12 determines that the document is tilted or non-standard, it further takes the difference between (X11−X13) and (X23−X21) to determine whether the document is tilted or negative. Determine which one it is. When the difference is out of the predetermined range (for example, when the document has an inclination opposite to the registration side and the reverse registration side), the CPU 12 does not incline the document. It is determined that the document is a non-standard document. If it is determined that the document is a non-standard document, a negative determination is made in step 106, and the calculation of the tilt angle θ and the tilt correction are not performed. If the difference between (X11−X13) and (X23−X21) is within a predetermined range, the CPU 12 determines that the document is tilted, and sets the tilt angle θ in a subsequent step. If the calculated value exceeds the threshold value, tilt correction is performed.

  (Modification 6)

  In the embodiment and the first to fifth modifications, whether or not the document is tilted is determined based on the edge positions on both the registration side and the reverse registration side. The determination may be made based on the edge position on the registration side. In this case, the inclination angle θ is also calculated based on a predetermined edge position.

  For example, when reading a document having a shape with one side deformed, the user sets the document by abutting the other side that is not deformed against a fixed guide for positioning provided in the document placement unit. Since there are many cases, the inclination may be determined based on the edge position on the side where the document is abutted (in this embodiment, the registration side).

  (Modification 7)

  In the embodiment and the first to fifth modifications, in obtaining data indicating the degree of inclination such as the inclination angle θ, the distance between the registration-side edge position and the registration-side reference position Q1, and the reverse registration-side edge position Whether to use the distance from the reverse registration side reference position Q2 is determined based on whether each edge position is located on the same straight line (detected from the same side), etc. However, which one to use may be set in advance.

  For example, when a user sets a document on the document placement unit, the user usually sets the document by placing one side of the document against a fixed guide for positioning provided on the document placement unit. Therefore, the distance between the edge position on the side where the document is abutted (the registration side in the above embodiment) and the reference position is set in advance so as to be used when obtaining data indicating the degree of inclination such as the inclination angle θ. It may be left.

  Further, the inclination angle θ on both the registration side and the edge side may be calculated, and if the calculation results of both are different, either one may be selected as the inclination angle. For example, when the inclination angle θ is different between the registration side and the reverse registration side, the smaller inclination may be selected so as not to overcorrect the inclination correction. Alternatively, the inclination angle θ on a predetermined side (for example, the registration side) may be selected.

  (Modification 8)

  In the embodiment and the first to seventh modifications, the inclination of the original is obtained by using the two reference positions of the registration side reference position Q1 and the reverse registration side reference position Q2 to obtain the distance from the detected edge position of the original. Although the example of determining is described, one reference position may be used. When there is one reference position, among the two edge positions detected in one line, the edge position group closer to the reference position and the edge position group farther from the reference position are distinguished from each other. The distance is obtained, and the edge position of at least one group is used to determine whether or not the document is tilted and to calculate the tilt angle θ.

1 is a block diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention. It is a block diagram of a scanner. It is a flowchart which shows an example of the flow of the inclination detection process program at the time of the image reading which CPU performs. It is explanatory drawing explaining an example of the inclination detection process performed based on the reading result of three line sensors. It is explanatory drawing explaining an example of the inclination detection process performed based on the reading result of two line sensors.

Explanation of symbols

10 Image Reading Device 12 CPU
14 RAM
16 ROM
18 I / O interface 20 Communication interface 22 Bus 24 CD-ROM drive 28 FD drive 34 Keyboard 36 Pointing device 38 Display 40 Scanner 78 CCD image sensor

Claims (9)

Conveying means for conveying the document to the document reading position;
A plurality of different pixel columns along the first direction, each for reading a plurality of pixel columns at predetermined intervals along a second direction intersecting the first direction. A document reading means for reading a document conveyed to the document reading position,
Edge detection means for detecting the position of the edge of the document conveyed to the document reading position based on the image signal for each pixel row read by each of the plurality of reading units;
An inclination detection means for detecting whether or not the document conveyed to the document reading position is inclined and at least one of the degree of inclination based on each of the edge positions detected by the edge detection means;
An image reading apparatus comprising: The edge detection means detects the positions of two edges for each pixel row read by the plurality of reading units,
The tilt detection means includes each of the positions of the edges closer to a predetermined reference position in the first direction and the other edge of the two edges for each pixel column detected by the edge detection means. The image reading apparatus according to claim 1, wherein at least one of whether or not the document conveyed to the document reading position is tilted and a degree of tilt is detected based on at least one of each of the positions. The edge detection means detects the positions of two edges for each pixel row read by the plurality of reading units,
The inclination detection unit is configured to detect the document based on each of the positions of the edges closer to the predetermined reference position in the first direction among the two edges for each pixel row detected by the edge detection unit. The image reading apparatus according to claim 1, wherein at least one of whether or not the document conveyed to the reading position is inclined and the degree of inclination is detected. The edge detection means detects the positions of two edges for each pixel row read by the plurality of reading units,
The inclination detecting means is a position of an edge in which each of the positions of the edges closer to a predetermined reference position is detected from the same side among the two edges for each pixel row detected by the edge detecting means. And whether each of the positions of the other edge is an edge position detected from the same side, and the edge of the edge determined to be the position of the edge detected from the same side is determined. The image reading apparatus according to claim 1, wherein at least one of whether or not the document conveyed to the document reading position is tilted and the degree of tilt is detected based on each position. The edge detection means detects the positions of two edges for each pixel row read by the plurality of reading units,
The inclination detection unit is configured to detect the document based on each of the positions of the edges closer to the predetermined reference position in the first direction among the two edges for each pixel row detected by the edge detection unit. The first detection process for detecting whether or not the document conveyed to the reading position is inclined and the degree of the inclination, and the document conveyed to the document reading position based on each of the positions of the other edge A second detection process for detecting at least one of whether or not it is tilted and the degree of tilt, and if the detection results of the first detection process and the second detection process are different, a predetermined edge The image reading apparatus according to claim 1, wherein a detection result of a detection process performed based on the position of the image is selected. The edge detection means detects the positions of two edges for each pixel row read by the plurality of reading units,
When detecting the degree of inclination, the inclination detection unit is closer to a predetermined reference position in the first direction out of two edges for each pixel column detected by the edge detection unit. Performing a first detection process for detecting the degree of inclination based on each of the edge positions and a second detection process for detecting at least one of the degrees of inclination based on each of the other edge positions; The image reading apparatus according to claim 1, wherein when the detection results of the first detection process and the second detection process are different, the detection result with the smaller degree of inclination is selected. When the degree of inclination is detected by the inclination detecting unit, the reading result of the original is corrected when a value indicating the degree of inclination detected by the inclination detecting unit is equal to or greater than a predetermined threshold. The image reading apparatus according to claim 1, further comprising a correction unit.   A non-transitory computer-readable storage medium storing a program for causing a computer to function as an edge detection unit and an inclination detection unit included in the image reading apparatus according to claim 1. Computer
A plurality of different pixel columns along the first direction, each for reading a plurality of pixel columns at predetermined intervals along a second direction intersecting the first direction. And reading the original conveyed to the original reading position by the conveying means based on the image signal for each pixel column read by each of the plurality of reading sections of the original reading means. Edge detecting means for detecting the position of the edge of the original document, and whether or not the original conveyed to the original reading position is inclined based on each of the edge positions detected by the edge detecting means. Inclination detecting means for detecting at least one of the degree of
Program to function as.

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