JP2009260608A - Image reader - Google Patents

Abstract

[PROBLEMS] To improve user operability and to accurately read a document with a simple configuration even when a document having irregularities such as a binding portion is placed obliquely with respect to a reading direction. An image reading apparatus is provided.
A scanner unit comprising an original table glass 1 on which an original 3 is placed and a movable scanner unit 2 that scans the placed original 3 and reads image information of the original. 2 based on the read image information and the measured height of the document 3. The height sensor 4 measures the height of the placed document 3 from the platen glass 1. , A shape estimation unit for obtaining a floating area floating from the platen glass 1 of the placed document 3, and an inclination angle correcting unit for correcting the area excluding the floating area.
[Selection] Figure 8

Description

  The present invention relates to an image reading apparatus such as a copying machine or a scanner capable of reading a document having an uneven surface such as a book document.

  2. Description of the Related Art Conventionally, an image reading apparatus that includes a reading surface for reading a document placed on a document table and optically reads the document by irradiating the document surface with light is widely known.

  However, some originals have a binding portion (unevenness) in which a plurality of sheet materials are integrally bound, such as a book original. For example, when reading such an original, the binding portion is lifted from the reading surface. Therefore, it is difficult to read the document accurately.

  In view of this, image reading apparatuses disclosed in Patent Documents 1 to 3 are known as conventional examples of image reading apparatuses that read an original having irregularities such as a binding portion of a book original.

  Patent Document 1 (Japanese Patent Laid-Open No. 8-97975) includes a reading unit having a photoelectric conversion element that reads an original document above the original table, and an original placed on the original table with the original surface facing upward. An image reading apparatus that performs a reading operation is disclosed.

  This image reading apparatus detects an edge portion of a document surface from an image read by an image pickup device, and measures the distance (high height) of the document surface by an outer shape measuring means for obtaining the outer shape of the document and a distance measuring mirror installed beside the document table. A) It is characterized by having a height detecting means for detecting.

  On the other hand, the image reading apparatuses disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 11-261792) and Patent Document 3 (Japanese Patent Laid-Open No. 2001-8000) place a document with the document surface facing downward. Is.

  The image reading device disclosed in Patent Document 2 is characterized in that image data is corrected based on a difference from a preset external size from image data read by scanning the document surface from below the document.

The image reading apparatus disclosed in Patent Document 3 includes a second illuminating unit that irradiates light in a straight line in a spread direction of a book document, in addition to an illuminating unit that irradiates light on a document surface in order to read the document. The second illumination means detects the height of the document surface from the document table. As described above, since the unevenness of the document surface is detected by the second illumination unit, it is possible to accurately read the document having the unevenness.
JP-A-8-97975 Japanese Patent Laid-Open No. 11-261792 Japanese Patent Laid-Open No. 2001-8000

  However, the image reading apparatus according to the conventional example has the following problems.

The image reading device disclosed in Patent Document 1 is an image reading device dedicated to a book document in which a document is placed so that the document surface faces upward and an image is read by a reading unit provided above the document table. The versatility is poor, and there is a high possibility of increasing the size and manufacturing cost. Further, since the document surface is facing upward, there is a problem that it is easily influenced by external light when reading an image, and the recognition of the sectional shape of the document becomes unstable.

  The image reading apparatus disclosed in Patent Document 2 can correct the read image data. However, the user must set the document size and the like in advance, and the operability for the user is reduced. Furthermore, there is a problem that the image data cannot be corrected accurately when the document is inclined obliquely with respect to the reading direction or when the document has document data in the binding portion of the document and the outline data is difficult to detect.

  Further, the image reading device disclosed in Patent Document 3 detects the exact height of the document surface by the second illumination unit, and corrects the image data by adjusting the focus and the image length according to the height. Is possible. However, when the document is placed obliquely with respect to the reading direction, the image data cannot be corrected accurately. Further, since the second illumination for detecting the height of the document surface is separately provided, there is a problem that the installation method is easily limited due to the relationship with other members, and the versatility is poor.

  In view of the above-mentioned present situation, the present invention improves user operability, and even when a document having irregularities such as a binding portion is placed obliquely with respect to the reading direction, the document can be accurately and accurately configured with a simple configuration. An object of the present invention is to provide an image reading apparatus capable of reading the image.

In order to achieve the above object, the present invention provides:
A document table on which the document is placed;
A movable imaging unit that scans a placed document and reads image information of the document;
In an image reading apparatus comprising:
A height measuring means which is movable together with the imaging unit and measures the height of the placed document from the document table;
An arithmetic means for obtaining a floating area of the placed original that is lifted from the original table based on the read image information and the measured height of the original;
Correction means for correcting the area excluding the floating area;
It is characterized by providing.

  According to the present invention, the user operability is improved, and even when a document having unevenness such as a binding portion is placed obliquely with respect to the reading direction, the document can be accurately read with a simple configuration. Therefore, it is possible to provide an image reading apparatus capable of performing the above.

  The best mode for carrying out the present invention will be exemplarily described in detail below based on the embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[First Embodiment]
The image reading apparatus according to the first embodiment of the present invention will be described with reference to FIGS. The image reading apparatus according to this embodiment mainly includes a document optical reading unit that optically reads a document, a height sensor unit that detects the height of the document surface, and estimates the shape of the document based on the detected data. And an inclination angle correction unit for correcting the inclination of the document shape. Therefore, the image according to the present embodiment is divided into (Description of the document optical reading unit), (Description of the height sensor unit), (Description of the document shape estimation unit), and (Description of the inclination angle correction unit). The reading device will be described.

(Description of the original optical reading unit)
2 and 3 are schematic configuration diagrams of the image reading apparatus according to the present embodiment. The image reading apparatus according to the present embodiment places the document 3 on the document table glass 1 as a reading surface so that the document surface faces downward. The document image information is optically read from below the platen glass 1 by a scanner unit 2 (imaging unit) as a document optical reading unit provided inside the apparatus main body.

  The scanner unit 2 is configured to be reciprocally movable in parallel with the document table glass 1 below the document table glass 1. The scanner unit 2 is provided with a light source (not shown). While moving in the direction of the arrow in FIG. 2, the light emitted from the light source is irradiated on the document surface and the reflected light is provided on the scanner unit 2. The image pattern is read by detecting with a one-dimensional CCD array (not shown).

  The image reading apparatus according to the present embodiment is provided with a control unit (not shown) that performs each control of the image reading operation, and the reflected luminance value read by the one-dimensional CCD array is the control unit. Are subjected to A / D conversion and stored in a frame buffer (not shown).

(Description of height sensor)
The height sensor unit 4 in the present embodiment will be described with reference to FIGS.

  In the image reading apparatus according to the present embodiment, a height sensor unit 4 (height measuring unit) configured to be movable together with the scanner unit 2 is mounted. The height sensor unit 4 measures the height of the document surface from the document table glass 1. According to this configuration, it is possible to measure the height of the document surface by the height sensor unit 4 at the same time that the scanner unit 2 reads the image pattern of the document.

  The height sensor unit 4 irradiates light on the document surface, receives light reflected from the document surface by a one-dimensional CCD array (not shown), and measures the height of the document surface by using a triangulation method. It is a contact type optical sensor.

  FIG. 3 is a schematic configuration of the image reading apparatus according to the present embodiment, and shows a state in which the height of the document surface is measured by the height sensor unit 4.

  The height sensor unit 4 in the present embodiment is installed 30 mm vertically below the platen glass 1, and is further moved and scanned by the scanner unit 2 at a position 80 mm away from the document abutting position (see FIG. 4). Mechanical scanning is performed in the same direction as the direction.

  FIG. 4 shows the scanning line 5 of the height sensor unit 4 when viewed from above the platen glass 1. As described above, the scanning position of the height sensor unit 4 passes through the binding portions of the sheet materials of all sizes placed on the document glass 1. Therefore, it is possible to measure the height of the irregularities such as the binding portion regardless of the size of the sheet material.

  In the present embodiment, the position of the height sensor unit 4 is set as described above, but the installation position of the height sensor unit 4 is not necessarily limited to this. It is also possible to change depending on the size of the sheet material used, the arrangement of other members, and the like.

When the height of the document surface is measured along the scanning line 5 shown in FIG. 4 by the height sensor unit 4, the measured one-dimensional height cross-sectional shape of the document surface is provided in the apparatus main body as data of all 2048 points. Stored in a storage area (not shown). In the present embodiment, the length that the height sensor unit 4 scans is 500 mm along the spread direction of the document, and the horizontal resolution of the height data stored in the storage area is 0.2 mm. It is.

  Then, by performing the following operation on the data of all 2048 points, two “document center part floating start positions” and “binding part center positions” are obtained. Here, the central portion of the document refers to a portion along the scanning line of the height sensor unit 4 of the document placed on the document table glass 1. Note that these operations are not performed by the user, but are performed by a control unit (not shown) that controls the image reading operation.

  First, a flag F indicating whether the document surface of the document placed on the document table glass 1 is floating from the document table glass 1 is set to zero.

  Next, the maximum value H_MAX of the height data of all 2048 points on the document surface is set to zero.

  Next, the float start position 1 at the center of the document, the float start position 2 at the center of the document, and the binding center position are set to zero.

  Thereafter, the processes of the following procedures 1 to 3 are sequentially performed from the first data to the 2048th data.

  Step 1: If F = 0, and the n-th height data of interest exceeds the specified threshold value h0, then F = 1 is set, and “the original document floating start position 1 = n”. To do.

  Procedure 2: If F = 1, and the n-th height data of interest is below the specified threshold value h0, then F = 1 and then “the document center floating start position 2 = n”. , F = 2.

  Procedure 3: If the noticed nth height data exceeds H_MAX, the noticed nth height data is set to H_MAX, and “binding portion center position = n” is set. At the same time, F = 1.

  After processing the 2048th data, if F = 0, the binding center position is set at the floating start position 1 of the document center and the floating start position 2 of the document center, and if F = 1, the document Float error handling is performed.

  The document center floating start position 1, the document central lift start position 2, and the binding center position calculated by performing the above processing are stored in a storage area of a control unit (not shown).

  A filter that uses infrared laser light having a wavelength of 730 nm for the light emitted from the height sensor unit 4 so as not to affect document reading, and at the same time, a filter that cuts infrared light in a normal document reading unit. Attached.

  In the present embodiment, a height sensor of a system in which laser light is irradiated and received by a CCD is used, but the height measuring method in the present invention is not limited to this system. For example, the same effect can be obtained even in a configuration in which an LED or the like is used as the light source, or a PSD (optical position detection element) or the like is used as the light receiving element.

(Description of manuscript shape estimation unit)
Next, along the processing flow shown in FIG. 1, a method for estimating the shape of the document based on the document center floating start position and the binding position center obtained from the measurement result of the height sensor unit 4 will be described. To do. In the present embodiment, the “original shape estimation unit (calculation means)” included in a control unit (not shown) estimates the original shape.

  When a book document is read by the scanner unit 2, since the binding portion is thick, when the book document is pressed against the document table glass 1, the document is inclined with respect to the scanning direction of the scanner unit 2. As a result, it has been difficult for the conventional image reading apparatus to accurately read a document. FIG. 5 shows a document read in a state where it is placed inclined with respect to the scanning direction, and a document read in a state where the binding portion is lifted from the document table glass 1.

  That is, in order to faithfully reproduce the read original, it is necessary to correct the image data of the original read in an inclined state so that the original is not inclined. Therefore, in the present embodiment, the shape of the document is estimated from the measurement result of the height sensor unit 4, and when the document is inclined as a result of the estimation, the inclination is corrected and image data is output. And

  A method for estimating the shape of the document will be described.

  First, the luminance gradient is calculated from the luminance value distribution (image information) of the original image read by the scanner unit 2, and “four points 6 indicating the outer position of the original” are estimated and detected. FIG. 6 shows the outline position (four points) 6 of the document. The outer position (four points) 6 of the original is used for rotationally correcting the read original later.

  Since “the degree of rotation of the document” differs between the left and right pages of the document, only “four points 6 indicating the outer position of the document” is insufficient for correcting the rotation of the scanned document. It is necessary to calculate the document floating start position (four points) 7 ”.

  Therefore, in order to calculate “the floating start position (four points) 7 of the read original”, two “original lift start positions” measured by the height sensor 4 described above are set to “height”. Inflection point (two points) 8 ”.

  FIG. 7 shows a cross section of the document with the binding portion raised. The “height inflection points (two points) 8” shown here are two points at the center of the document that the height detection sensor 4 scans along the scanning line 5 (height detection line). Based on these two points, the following procedure is performed to determine “the reading document floating start position (four points) 7” at the upper and lower ends of the page.

  If the “floating position of the read original (four points) 7” at the upper and lower ends of the page can be obtained, the four points surrounding the left and right pages (rectangular areas 18 and 19) of the original can be recognized. It is possible to estimate the shapes of the left and right pages 18 and 19. Note that an area surrounded by “the reading document floating start position (four points) 7” is referred to as a “floating area”.

  First, as shown in FIG. 8, a straight line passing through two points “four points indicating the outline position of the document” on the left page is calculated, and an upper left straight line 9 and a lower left end point that intersect perpendicularly with the straight line and pass through the upper left end point are calculated. The lower left straight line 12 is calculated. Similarly, an upper right straight line 10 passing through the upper right end point of the right page and a lower right straight line 11 passing through the lower right end point are calculated.

  Further, an intersection of the upper left straight line 9 and the upper right straight line 10 is obtained, and a center line connecting the intersection and H_MAX is calculated. Here, the linear equation at the upper end of the left and right pages is used, but the linear equation at the lower end may be used.

Next, the calculated center line is divided into left and right pages, and “the floating start position (four points) 7 of the read document” is obtained. Here, with reference to FIG. 8, a process for obtaining “the floating start position (four points) 7 of the read document” on the left page will be described.

  From the position of H_MAX and the “height inflection point (two points) 8” on the left page, “the width of the contact surface between the document table and the center of the document” on the left page in the “scanning unit scanning direction” shown in FIG. The “floating width at the center of the document” is calculated.

  Further, a length obtained by adding the “contact surface width between the document platen and the document central portion” on the left page and the “floating width of the document central portion” is defined as “the document width at the central portion” on the left page. In addition, the distance between the upper left end point of “four points 6 indicating the outer position of the document” and the center line is calculated and is set as “the document width at the upper left”. Here, the following formula is calculated to obtain “the upper left floating width”.

“Upper left float” = “Center document width” × “Original center float” / “Upper left document width”

  From the obtained “upper left floating width” and “original central center floating width”, a straight line for starting the left page floating is obtained, and the intersection of this straight line and the upper left straight line 9 is defined as “the floating start position of the read original ( (4 points) 7 ”. Further, an intersection of the straight line at which the page starts to float and the lower left straight line 12 is set as “the floating start position (four points) 7 of the read document” at the bottom of the left page. Similar processing is performed on the right page. Through the processing so far, the “floating start position (four points) 7 of the read document” is estimated.

  From the above, it is possible to estimate the rectangular areas 18 and 19 on the left and right pages necessary for the rotation correction of the read document image. The rectangular areas 18 and 19 correspond to portions obtained by removing the “floating area” from the document. A method of correcting the document position will be described below using the “document floating start position (four points) 7 at the upper and lower ends” and “document outer position (four points) 6” obtained here.

(Description of tilt angle correction unit)
In the image reading apparatus according to the present embodiment, the rectangular regions 18 and 19 (regions excluding the floating region) of the left and right pages of the document image estimated by the document shape estimation unit are rotationally moved to correct the position. A “tilt angle correction unit (correction means)” is provided. Hereinafter, the “tilt angle correction unit” will be described.

  First, in order to rotate and move the rectangular areas 18 and 19 (areas excluding the floating area) of the left and right pages of the original image, and to correct the position, the right and left pages are inclined with respect to the “scanner scanning direction (movement direction)”. It is necessary to find the corner.

  Therefore, the inclination angles θ1 (15) and θ2 (16) with respect to the “scanner scanning direction” are obtained from the position data of the rectangular areas 18 and 19 on the left and right pages, respectively. The position data of the rectangular areas 18 and 19 on the left and right pages have already been obtained in the “original shape estimation unit” described above.

  FIG. 9 shows the inclination angles θ1 (15) and θ2 (16) used for the rotational movement. From the scanning line parallel line 17 of the scanner unit 2 and the upper left point of the “original document position (four points) 6” in the left rectangular area 18 and the upper left point of the “document floating start position (four points) 7 at the upper and lower ends” θ1 (15) is calculated. Similarly, θ2 (16) is calculated in the right rectangular area 19.

  Next, rotational movement is performed with respect to the left and right rectangular regions 18 and 19 using θ1 (15) and θ2 (16). FIG. 10 shows the positions of the center point 20, the left rectangular area upper end line 21, and the right rectangular area upper end line 22 used when performing the rotation operation.

First, the distance between the two points at the upper end and the distance between the two points at the lower end of “the document floating start position at the upper and lower ends (four points) 7” is calculated. At the end with the shorter distance between the two points, the next rotational movement is performed. The upper end lines of the left and right rectangular areas 18 and 19 are extended, and the intersection of the left rectangular area upper end line 21 and the right rectangular area upper end line 22 is set as the center point 20.

  Then, θ1 (15) and θ2 (16) are rotated around the center point 20, respectively. Here, the binding area of the document, that is, the rectangular area (floating area) surrounded by “the document floating start position (four points) 7 at the upper and lower ends” 7 is erased before the rotation operation in the present embodiment. . As described above, an image whose position is corrected is obtained.

(Comparison with conventional example)
As described above, the image reading apparatus according to the present embodiment is based on “the height of the original position (four points) 6” read by the scanner unit 2 and “height change value” read by the height sensor unit 4. The apparatus has a configuration for estimating a document shape and correcting a tilted document.

  With this configuration, even when the original is placed with an inclination with respect to the scanning direction of the scanner unit 2, it is possible to reproduce an output duplicate printed matter that is faithful to the original. Further, since the position and height data of the document is detected simultaneously with the scanning, the user does not need to set the document size and the like in advance, and as a result, the user operability can be improved.

  Further, it is not necessary to separately provide a special device or the like for reading an image and correcting it, so that it is possible to prevent an increase in the size of the device body and an increase in manufacturing cost.

  Hereinafter, the effects of the image reading apparatus according to the present embodiment will be described in more detail after comparing with the image reading apparatus according to the conventional example.

  Conventionally, the reflected light intensity from the document surface is read by an image reading sensor, and the document floating start position (four points) is estimated from the density information of the read image. Specifically, the position where the read image becomes dark is set as the position where the document starts to float (four points).

  Therefore, when there are characters / images in the vicinity of the document floating start position (four points), the density of the portion where the characters / images are present becomes dark, and an error occurs in the estimation of the document floating start position (four points) 7. There was a case. As a result of not being able to accurately detect the document floating start position (four points), there arises a problem that a document having an image on the binding portion of the book document cannot be reproduced faithfully.

  On the other hand, in the present embodiment, since the height sensor unit 4 is used to measure the height (floating) of the document surface from the platen glass 1, the document floating start position (four points) 7 is accurately set. Can be estimated. Therefore, there is no error in estimating the position of the floating area, and the inclination of the document can be corrected accurately.

  FIG. 11 shows an image read by the image reading apparatus according to the conventional example and an image read by the image reading apparatus according to the present embodiment.

  Comparing the read image in the conventional example with the read image in the present embodiment, as shown in FIG. 11, the originals inclined at different angles on the left and right pages are corrected horizontally, and the original can be reproduced faithfully. Yes. Further, in the present embodiment, the dark and shadowed portion of the document binding portion is deleted to make it easy to see.

[Second Embodiment]
An image reading apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the rectangular area (original floating area) surrounded by “the original floating start position (four points) 7 at the upper and lower ends” 7 is erased before the rotation operation in the present exemplary embodiment. It was.

  On the other hand, the present embodiment is characterized by having a restoration processing unit that restores data using a lookup table (hereinafter referred to as LUT) without erasing it. Since the configuration other than that is not different from that of the first embodiment, the description thereof is omitted, and here, a method for restoring the document binding portion using the LUT will be described.

(Restoration processing for original binding)
An image is also formed on the document binding portion, and when this is read, the document binding portion is lifted from the platen glass 1, so that the image of the document binding portion is distorted or blurred, and characters and images are accurately displayed. It is difficult to faithfully reproduce document data, such as being unable to read. The document binding portion referred to here corresponds to a “floating area” where the document is lifted from the platen glass 1.

  In the present embodiment, the document binding unit is restored by performing the following steps, and a “restoration processing unit (restoring unit)” that corrects and corrects distortion and blur of the document binding unit is provided. Features. In the present embodiment, it is assumed that the restoration processing unit is included in a control unit (not shown) that controls the image reading operation.

  First, before rotationally correcting the read image data, the left and right document binding portion rectangular regions 24 and 25 are estimated from “the left and right page rectangular regions 18 and 19 estimated by the shape estimation unit (see the first embodiment)”. To do.

  Since the slopes of the rectangular areas of the left and right pages change with respect to the center of the document, first, the center point 20 obtained by the method described in the first embodiment and the maximum height position H_MAX detected by the height sensor unit 4 are used. Is used to estimate the center line 23.

  FIG. 13 shows the position of the center line 23. From the center line 23 and the “document floating start position at the top and bottom (four points) 7”, the “center position of the top and bottom (two points)” that divides the entire document into left and right pages is obtained.

  Thereafter, similarly to the rotational movement of the left and right rectangular areas 18 and 19 described in the first embodiment, the left and right binding rectangular areas 24 and 25 that are the document floating areas are rotationally moved.

  That is, the binding portion is divided into “left and right binding portion rectangular areas 24 and 25” based on “the center position of the upper and lower ends (two points)” and “the document floating start position at the upper and lower ends (four points) 7”. Then, it is rotated based on the inclination angles θ1 (15) and θ2 (16) calculated by the method described in the first embodiment, and the inclinations of the binding portion rectangular areas 24 and 25 on the left and right pages are corrected. FIG. 14 shows a document in a state where a rotation operation is performed to correct the inclinations of the bound rectangular regions 24 and 25 on the left and right pages.

  Next, a process for restoring the images formed in the corrected binding rectangular regions 24 and 25 on the left and right pages will be described below.

  Characters and images in the document lifting area are inclined because they are lifted from the document surface, and are reduced as they move away from the document surface. FIG. 15 shows how characters and images in the document floating area are reduced. Therefore, in the present embodiment, the following processing is performed to correct the inclination (inclination angle 26) and distortion (magnification) of the document floating area on the left and right pages.

First, the bending angle α27 is calculated from “the document floating start position at the upper and lower ends (four points) 7”. Here, (H_MAX) detected by the height sensor unit 4 is defined as Cy. The distance from the floating start position to (H_MAX) is Cx (refer to FIG. 15 for details of Cx and Cy). In the case of α = 0 degrees, the original position x ′ from which the distortion at a certain position x in the document floating area is removed is obtained by Expression (1).

  Using the expression 1, the position x in the document floating area is sequentially converted to x ′.

  In the case of 0 ° <α <90 °, after performing the same processing as in the case of α = 0 °, using the affine transformation matrix with the center of the document in the direction perpendicular to the scanning direction of the scanner unit 2 as the center of gravity, Turn the bend angle α °.

  Then, a lookup table (LUT) for the above processing is created, and the LUT is used to convert the image position of the document floating area read by the scan unit 2 to the original position x ′ from which distortion has been removed. If α = 90 °, error output is performed.

  The image data in the document floating area is restored by the above operation. FIG. 16 shows a document in which the document floating area is corrected. In this embodiment, the inverse transformation is performed by referring to the lookup table for the part and curved surface restoration. However, the restoration method in the present invention is not limited to this, and the inverse transformation using the curved surface formula is performed. It doesn't matter.

(Comparison with conventional example)
As described above, according to the present exemplary embodiment, even with a concavo-convex document such as a binding portion of a book document, the concavo-convex region and height of the document surface are detected using one height sensor unit 4 and conversion using the LUT is performed. Correction was made in the process.

  As a result, the read original can be restored to the original undeformed state, and the output duplicate printed matter can be reproduced faithfully to the original. In addition, since the document outline data and height data are detected at the same time as scanning and the binding area is calculated, the user does not need to set the document size in advance, and the user operability can be improved. It was.

  In the conventional method for correcting distortion of the original binding portion, the inclination and distortion of the original binding portion are corrected from the intensity of light from the original surface and the density information of the read original surface. For this reason, when there are characters or images in the document floating area, the entire area becomes dark, so that correction cannot be performed correctly, and the correction depends on the document data.

  In addition, since the density information of the document surface is calculated based on the intensity of the reflected light from the document surface, the height and the inclination are calculated from the calculated information, and further, the processing for correcting the floating area of the document binding portion is performed. There has been a problem that the correction processing takes time as it increases.

  In the present embodiment, the left and right pages are placed in the undistorted original area and the original binding area, based on “indicating the outline position of the original (four points)” and “height change amount” detected by the height sensor unit 4. By performing the division / correction processing, the original can be faithfully reproduced regardless of the original data.

FIG. 17 shows a document read by the method in the conventional example and a document read by the present embodiment.
When comparing the document read by the method of the conventional example with the document read by the present embodiment, the document inclined at different angles on the left and right pages of the binding portion of the book document is corrected horizontally, and the uneven portion of the document binding portion is further corrected. The distortion and blurring of the characters are corrected so that even uneven parts can be read.

  Therefore, according to the image reading apparatus according to the present embodiment, it is possible to provide an image reading apparatus that can accurately read and reproduce an image even if the binding portion of the document includes an image. become.

Processing flow of image reading operation in the first embodiment 1 is a schematic configuration diagram of an image reading apparatus according to a first embodiment. 1 is a schematic configuration diagram of an image reading apparatus according to a first embodiment. The figure which shows the scanning position of the height sensor part in 1st Embodiment. Diagram showing the document tilted with respect to the scanning direction The figure which shows the external shape position (four points) and the document center position of the document in the first embodiment The figure which shows the cross section of the original document in which the binding part floated in 1st Embodiment Explanatory drawing for obtaining the floating start position (four points) of the read document in the first embodiment The figure explaining the inclination-angle of the shape of the document in 1st Embodiment The figure which shows the position of the center point at the time of performing rotation correction in 1st Embodiment, and an upper end line Comparison of scanned document between the conventional example and the first embodiment Processing flow of image reading operation in the second embodiment Image in a state before the rotation correction is performed in the second embodiment Image after rotation correction in the second embodiment The figure which shows the reduction degree of the image in the original floating area of 2nd Embodiment Image after restoring the document floating area in the second embodiment Comparison of an original restored image and a conventional scanned image

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Original plate glass 2 Scanner unit 3 Original 4 Height detection sensor part 6 Point which shows the external position of the original 7 Original floating position 8 Original floating position 9 Upper left straight line 10 Upper right straight line 18 Left rectangular area 19 Right rectangular region

Claims (6)

A document table on which the document is placed;
A movable imaging unit that scans a placed document and reads image information of the document;
In an image reading apparatus comprising:
A height measuring means which is movable together with the imaging unit and measures the height of the placed document from the document table;
An arithmetic means for obtaining a floating area of the placed original that is lifted from the original table based on the read image information and the measured height of the original;
Correction means for correcting the area excluding the floating area;
An image reading apparatus comprising: The correction means includes
The image reading apparatus according to claim 1, wherein the position of the area excluding the floating area is corrected by rotationally moving the area excluding the floating area. The rotational movement is
The image reading apparatus according to claim 2, wherein the image reading apparatus is performed based on an inclination angle of an area excluding the floating area with respect to a moving direction of the imaging unit.   The image reading apparatus according to claim 1, further comprising a restoration unit that restores image information of the floating area. The restoration means includes
The image data of the floating area has a look-up table that converts the image information of the floating area into an original state that is not lifted from the platen, and the image information of the floating area is restored based on the look-up table. Item 5. The image reading apparatus according to Item 4. The lookup table is
6. The image reading apparatus according to claim 5, wherein the image reading apparatus is created based on height information measured by the height measuring means.

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