JP2007158813A - Image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading device for preventing not only a printing surface wanted to be read but also a portion needless to be read such as a small lot from being read when an original such as a book etc. is to be read. <P>SOLUTION: In the image reading device for reading an image of a reading surface and having a light source for irradiating a light to a reading surface of an object such as a book etc., an optical system (a reflection mirror A, a light path expansion and contraction member B, and an imaging lens C) for forming a light path of a reflected light from the reading surface, and a photoelectric transfer element D for performing imaging process from the reflected light, height of the reading surface is to be measured from the read image, and a reading area of the image is to be set, based on information of the height. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus having a function of correcting a curved image of a document such as a book.

  Many inventions for reading books have been filed that correct the curved image of a manuscript to a flat surface. However, in the prior art, both the edge portion and the plate surface portion are read, and then the necessary portions are cut out by image processing. ing.

The technique of Patent Document 1 is an invention for creating a high-quality flat image by processing a plate surface (front surface) of a book by using a shape recognition unit and a calculation unit. Patent Document 2 is also an invention that detects distortion including shape distortion caused by a torsion peculiar to a book document, corrects distortion of a read image caused by the shape distortion, and creates an image without distortion.
JP-A-5-219323 Japanese Patent Laid-Open No. 11-4325

  However, if a correction method that reads both the edge portion and the plate surface portion is performed, these factors may affect the correction accuracy. Therefore, in order to improve the accuracy of correction, it is better to perform correction after removing such influence in advance. This is especially true when the target document is a three-dimensional object. Such technology has not been taken into consideration in the technology of the above-mentioned patent documents.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus that avoids reading not only a printing plate to be read but also a portion that does not need to be read, such as a small edge, when reading a document such as a book. In particular, an object of the present invention is to provide an image reading apparatus that, when reading a three-dimensional object, determines whether the three-dimensional object is placed or not, and whether or not all reading is possible with one reading.

  An aspect of the present invention that achieves the above object includes a light source that irradiates light on a reading surface of an object, an optical system that forms an optical path of reflected light from the reading surface, and an imaging unit that performs an imaging process from the reflected light. In the image reading apparatus for reading an image on the reading surface, a height of the reading surface is measured from the read image, and an image reading range is set based on the information on the height. .

  Here, the measurement range when measuring the height is set wider than the reading range.

  Moreover, it has a determination means which determines whether the said object is settled in the said reading range based on the information of the said height.

  Moreover, it has a display means which displays the result of the said determination means, It is characterized by the above-mentioned. The display means displays that the object is to be moved within the reading range. Further, the display means performs a display instructing to perform an operation of reading an image on the reading surface a plurality of times when the object does not fall within the reading range.

  When the object is a book, a boundary between the edge of the book and the printing plate is detected based on the height information.

  Reading of a region such as a fore edge that affects correction when reading an image can be avoided, and correction accuracy can be improved.

  Hereinafter, the best mode for carrying out the image reading apparatus of the present invention will be described. In the description, the drawings submitted at the same time as this specification will be appropriately referred to.

  FIG. 1 is a schematic diagram of the inside of the image reading apparatus of the present embodiment. In FIG. 1, A is a reflecting mirror, which is arranged on the upper part of the image reading apparatus. A reading window is provided on the upper part of the image reading apparatus so that reflected light when incident light from an AF projection lamp 39 (described later) is reflected on the original is incident on the reflecting mirror A. The reflection mirror A is rotatable around a rotation axis parallel to the element arrangement direction of the photoelectric conversion element (CCD (Charge Coupled Device)) shown in D, and a light beam incident from the position a to the position b is perpendicular to the reference plane. Reflected in the direction of the correct position c. Thereafter, the light beam is reflected by the mirror of the optical path expansion / contraction member B, follows the path cd, enters the photographing lens C, and is condensed and forms an image on the photoelectric conversion element D. Thus, an optical system for forming an optical path of incident light is formed by the reflecting mirror A, the optical path expansion / contraction member B, and the photographing lens C. The photoelectric conversion element D performs imaging processing from the imaged light and converts it into an electrical signal. The image reading apparatus has a function of correcting the shape distortion of the document when generating image data from the converted electric signal, and generates a read image without distortion.

  In FIG. 1, the operating directions of the reflecting mirror A and the optical path expansion / contraction member B are indicated by arrows. Here, the reflecting mirror A and the optical path expansion / contraction member B, which are both operating objects, have a structure that can be operated separately by independent driving sources (not shown). The photoelectric conversion element D is fixed to the image reading apparatus main body and does not operate. The taking lens C is basically structured not to operate.

  The size (magnification) of the image taken here is the length from the original to the front principal point of the photographing lens C (position a to position e1 in FIG. 1) and the photoelectric conversion element from the rear principal point of the photographing lens C. It is determined by the ratio of the lengths up to D (position e2 to position f (see the optical path schematic diagram in FIG. 2)). However, in a device that performs photographing in the perspective direction, the length of the front principal point of the photographing lens C from the document varies depending on the change in the perspective direction distance (ab).

  If this is photographed as it is, the magnification changes depending on the perspective angle (the size of the image changes, and the square image becomes a trapezoidal image), and the focus is also shifted. In order to correct this defect, the optical path expansion / contraction member B is operated according to the rotation angle of the reflection mirror A, the length from the original to the front principal point of the photographing lens C is kept constant, the image size changes, the focus We will prevent displacement.

  The start position of image reading is determined by providing a position detection sensor at the part where the rotation angle of the mirror appears large so that the variation of the start position is reduced, and the end position is not determined by the position of the mirror or cam, but is specified. This is defined with the time when the number of line reads in is complete. This is because, when the number of read lines is large, if the end position is defined by a mirror angle or the like, the number of read lines becomes large and the number of read lines becomes excessive or insufficient.

  The reflection mirror A and the optical path expansion / contraction member B are performed by a pulse motor that easily controls the operation amount. However, since the scan speed, the reflection mirror angle change, and the optical path expansion / contraction member change are not linearly related, in this embodiment, the cam Make that action by the face.

  In the case of photographing a sheet object, the optical path expansion / contraction member B may be operated so as to correct the length from the mirror to the reference plane. On the other hand, in the case of photographing a three-dimensional object, the three-dimensional object is operated according to the distance measurement result, and the required mirror operating angle width is increased and the position is also different. For this reason, two cam surfaces are created on the cam member, and these are used by switching according to the selection of the original (sheet or three-dimensional object). The optical path expansion / contraction member is actuated by the operation of the cam, and when the photographed object is a sheet object, the distance from the photographing surface to the principal point of the photographing lens (distance from the photographing surface to the CCD light receiving surface) is kept constant. .

  FIG. 3A is a diagram showing the reflecting mirror and the operating system. In FIG. 3A, D is a reflecting mirror, A is an operating motor, and the mirror cam of B is rotated through a speed reduction mechanism. The cam follower C pressed against the cam surface rotates the reflection mirror to change the reflection angle.

  FIG. 3B shows a schematic diagram of the operating system of the optical path expansion / contraction member. In FIG. 3B, A is an operating motor, B is an optical path telescopic mirror, C is a telescopic member guide, D is a guide shaft, E is an optical path telescopic cam, F is a cam follower, and G is a departure position detection sensor. First, the rotation of the actuation motor A rotates the optical path telescopic cam E via the deceleration system, and the optical follower mirror B moves up and down along the guide axis D by the cam follower F receiving the cam surface. The starting point is detected by the starting position detection sensor G.

  FIG. 3C shows the cam shape of the optical path telescopic cam E. One side of the preparation working surface (c-a) is a cam used for photographing a sheet document, and a cam 1 part (ab in the figure). And a cam 2 part (c-d part in the figure) used for photographing a three-dimensional object is provided on the other side. The cam surface to be used is changed depending on the manuscript for photographing the cam. The three-dimensional object cam on the cam surface cd has a larger cam drop than the sheet original cam on the cam surface ab, and the optical path expansion / contraction member can be operated within a large range.

  Next, the measurement principle for measuring the height of each position on the reading surface by the height measurement function of this embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram of the principle of measuring the height of the reading surface when the image is read with the page of the book opened upward in the image reading apparatus of the present embodiment. 4A shows the relationship between the image reading apparatus and the book binding portion, and FIG. 4B shows an exploded view of an AF (Auto Focus) projection lamp 39. The AF floodlight 39 is a light source that emits slit-shaped light for height measurement from the window portion 7 in FIG.

  As shown in FIG. 4A, the image reading apparatus according to the present embodiment is arranged so that the wall surface 2 of the housing 1 is parallel to the binding portion 101 when the page of the book is opened. 100 reading is possible. The narrow-width reading light is irradiated in parallel to the binding unit 101, and an image recorded on the reading surface 100 while being scanned line-sequentially in the scanning direction intersecting the binding unit 101 at the same height portion of the reading surface 100. Is read. Note that a book whose pages are opened can be read on both sides at once, or can be read page by page.

  As a result, one page is divided into small areas, the surroundings of the small areas are overlapped and shot, and these are pasted together to create a single copy image. This can be eliminated. Further, as shown in FIG. 4A, the height of each position of the reading surface by the height measuring function is measured by tilting the reading surface 100 with the AF floodlight 39 from the window portion 7 provided in the upper right portion of the wall surface 2. For example, the slit-shaped measurement light 130 is radiated between AB. When the reading surface is flat, the slit-shaped measurement light becomes a straight line, but in the case of a book with unevenness on the reading surface, it becomes a curve as shown in FIG.

  As shown in FIG. 4B, the AF floodlight 39 is composed of a condenser lens 39a, a stop 39b provided with a slit-like opening, a light emitting element 39c, and a reflector plate 39d. The For example, light emitted from a light emitting element 39c made up of an LED (Light Emitting Diode) is narrowed by a diaphragm 39b to form a slit, and the measurement light with high luminance is not scattered by the action of the condenser lens 39a. Can be irradiated.

  Next, with reference to FIGS. 5 and 6, the positional relationship when the measurement light from the AF light projection lamp 39 is irradiated onto the document surface will be described. FIG. 5 is a diagram showing an example of the positional relationship when the original light is irradiated with the measurement light from the AF light projection lamp 39.

  As shown in FIG. 5, the wall surface 2 of the housing 1 of the image reading apparatus according to the present embodiment is arranged at a predetermined interval on the side of the original reading surface ABCD 100 at a height H position on the upper right portion of the wall surface 2. Irradiation between the reading surfaces BC is performed by slit-shaped measuring light 130 so as to obliquely cross the reading surface 100 from the provided window portion 7 by the AF floodlight 39. The distance between the wall surface 2 of the housing 1 and the reading surface 100 is y2, and the size of the reading surface 100 is x1 between AB and y1 between AC, and the distance from the window 7 to one end of the reading surface 100 is x2. .

  6 is an orthographic view of the reading surface ABCD shown in FIG. 5, where (a) is a plan view seen from directly above, (b) is a right side view seen from the x direction, and (c) is a y direction. It is the front view seen from. In FIG. 6, BC represents slit-shaped measurement light, and EB and EC represent optical paths of measurement light emitted from the AF floodlight 39.

  For convenience of explanation, a state where the reading surface ABCD is lifted by h is considered. Then, the intersections B and C of the light beam emitted from the AF projection lamp 39 and the reading surface are represented by B ′, B ″, C ′, in the right side view of (b) and the front view of (c). C ″, and B ′ and C ′ in the plan view. That is, when the reading surface is lifted by h, the line segment BC in the plan view is shifted to a line segment B′C ′, which means that the larger the h is, the more the line segment BC is shifted to the right. Therefore, the position (x3, y3) on the line segment BC of the reading light L at a distance y3 from the front on the reading surface is k1, and the position (x4, y3) on the line segment B′C ′ is k2, and h , And the relationship with the distance between K1 and K2.

Now, if CD is the X coordinate and AC is the Y coordinate, the slit-shaped measurement light BC is
Y = (y1 / x1) * X
It is represented by

The slit-shaped measuring light B′C ′ is
Y + (y2 * h / H) = (y1 / x1) * {X− (x2 * h / H)} X = (x1 / y1) * {Y + (y2 * h / H)} + (x2 * h / H)
It is represented by

  Therefore, if (x4−x3) is xm, the relationship h = xm * H * {y1 / (y2 * x1 + x2 * y1)} is obtained. Therefore, if the reference position of the slit-shaped measurement light BC in a state where the reading surface is flat is stored and the difference from the actually measured position is obtained, the height (lift amount) at each position on the reading surface is obtained. be able to.

The case of reading a book will be described below with reference to FIG. When reading a book having a shape as shown in FIG. 7, when a distance measuring operation is performed in order to recognize the shape of the book (that is, to detect the inclination of each part), sampling as shown in FIG. 7 (X0 to X3) Is performed, the inclination between X0-X1, X1-X2, and X2-X3 is detected in the maximum height section from the edge of the book, but the reading object is a book in advance. When the distance is measured on the boundary line between the edge and the plate, only two types of inclinations are detected in the above section. The fact that the three types are detected indicates that the inclination between X1 and X2 is invalid, and there is a boundary line between the edge and the plate surface between X1 and X2. Further, it can be seen that the boundary line between the fore edge and the printing plate is a place corresponding to the intersection of the straight line X0-X1 and the straight line X2-X3. If the horizontal position of the book is X0... Xn and the height relative to it is h0.
Y-h0 = h1-h0 / X1-X0 (X-X0)
The straight line X2-X3 is
Y-h2 = h3-h2 / X3-X2 (X-X2)
It becomes.

From the above two equations, if the boundary coordinates are (XB, hB), the reading start point XB is
[(H1-h0) (X3-X2) X0- (h3-h2) (X1-X0) X2 + (h2-h0) (X1-X0) (X3-X2)] / [(h1-h0) (X3- X2)-(h3-h2) (X1-X0)]
The height hB at that point is
[(H3-h2) (X1-X0) h0- (h1-h0) (X3-X2) h2 + (X2-X0) (h3-h2) (h1-h0)] / [(h3-h2) (X1- X0)-(h1-h0) (X3-X2)]
It becomes.

Also, assuming that the height from the document surface to the rotating mirror is H and the angle of the rotating mirror at the start of reading is θ _B ,
tanθ _B = XB / (H−hB)
It becomes. When reading a book with this image reading device by the above method, the reading start point is obtained by measuring the height of each part of the book with the distance measuring device provided in this device, and after the distance measurement is completed, the reading is performed. Read from the starting point.

  Next, in the image reading apparatus of this embodiment, a state in which the distance measurement range is set wider than the reading range on the reading start side and the reading end side in the sub-scanning direction is shown in FIG. In order to detect the height from the document surface, the distance measuring device can identify a section set in the distance measuring range as a section within the reading range and a section outside the reading range. Furthermore, it is possible to identify the reading start side (the front side of the apparatus main body) and the other side (the side far from the apparatus main body) in the section outside the reading range.

  Next, with reference to FIG. 9, the operation process when the three-dimensional object is larger than the reading range will be described. When the image reading apparatus according to the present embodiment reads a three-dimensional object as shown in FIG. 9, the height from the document surface is detected on both the front side and the other side outside the reading range. An object cannot be fully read in a single reading. Therefore, it is necessary to take measures such as reading by dividing into a plurality of times and reading only a necessary part. The user can recognize the detected content by the display device or the indicator provided in the image reading device with the read information.

Further, in the case as shown in FIG. 10, the three-dimensional object is within the reading range on the other side outside the reading range, but on the near side, it is outside the reading range. At this time, if the length from the end of the three-dimensional object outside the reading range on the near side to the reading range (Lsout) <the length from the end of the three-dimensional object on the far side to the reading range (Lein), the three-dimensional object is on the other side It can be seen that the entire three-dimensional object is within the reading range by moving in the direction. The read information can be recognized by the user using the display device provided in the image reading device or the indicator. That means
Lein-Lsout> 0 ... Formula (A)
If so, it is within the reading range. In other cases, the entire reading cannot be performed by one reading. The image reading apparatus according to this embodiment includes a determination unit that determines whether or not the entire image can be read by one reading. The case where a spread book is read using such technical contents will be described below.

  When the width of the spread book is within the reading range as shown in FIG. 11, a flat portion having no inclination at both ends is detected using the distance measuring device of the image reading apparatus of this embodiment.

  However, when the width of the spread book exceeds the reading range as shown in FIG. 12, a height is generated at the reading range boundary portion. At this time, the image reading apparatus uses the data detected by the distance measuring device to detect the reading start point and the node portion, and the reading is performed from the reading start point to the node portion. When this reading is completed, the apparatus is connected to the liquid crystal display as the display apparatus provided, or a part equivalent thereto, or the computer display connected to the apparatus on the near side and the other side of the book document. A display for instructing to be replaced is performed. The user sees this display, swaps the front and the other side of the spread book, and starts reading.

  Next, an example of the display method of the image reading apparatus for the position where the reading object is placed when reading the three-dimensional object will be described below.

  FIG. 13 shows a display panel as a display device included in the image reading apparatus of this embodiment. In FIG. 13A, the display panel is provided in the lower part of the image reading apparatus casing. In FIG. 13B, the display panel shows LEDs 1 to 4 as light emitting elements. The LED 1 blinks red when a three-dimensional object is placed on the near side beyond the reading range, and lights green when it is within the reading range on the near side. The LED 2 blinks red when a three-dimensional object is placed beyond the reading range on the other side, and lights green when it is within the reading range on the other side. When the LED 3 is lit, it means that the entire three-dimensional object can be read at a time by moving the three-dimensional object toward the near side as shown in FIG. When the three-dimensional object is moved to the front and within the reading range, the LED 3 is turned off, and the LED 2 is turned on in green from flashing red. The lighting of the LED indicates that the entire three-dimensional object can be read at one time by moving the three-dimensional object in the opposite direction. That is, both LED3 and LED4 are lit when the formula (A) is established.

  An example of the operation of the display device when reading a book will be described below. FIG. 14 illustrates the state of the display panel when reading a book. When it is detected that the reading start position of the book is outside the reading range, the LED 4 is turned on (see (a)). Therefore, when the book is moved in the opposite direction and the reading start position is within the reading range, the LED 4 is turned off and the LED 1 is lit in green (see (b)).

  From the above description, the following effects can be obtained by implementing the image reading apparatus of the present embodiment. That is, when reading a plurality of originals having different inclinations such as a book, it is possible to set the reading start position by detecting the boundary between the fore edge and the printing plate by utilizing the feature of the shape of the book. In particular, when a three-dimensional object is read, it is possible to confirm the place of placement, and it is possible to determine whether or not all images can be captured by one reading. Therefore, reading of a region such as a fore edge that affects correction when reading an image can be avoided, and correction accuracy can be improved.

  The above-described embodiment is the best for carrying out the present invention, but the present invention is not limited to this. Therefore, various modifications can be made to the mode of implementation of this embodiment without departing from the scope of the present invention.

  Development of scanners, copiers, and photographing devices as image reading devices is desired.

It is a schematic shape diagram of the inside of the image reading apparatus of the present embodiment. It is a schematic diagram of an optical path of the image reading apparatus of the present embodiment. FIG. 2A is a diagram showing a reflection mirror and an operation system, FIG. 2B is a schematic diagram of an operation system of an optical path expansion / contraction member, and FIG. FIG. 5 is an explanatory diagram of a principle of measuring the height of a reading surface when an image is read by opening a page of a book upward in the image reading apparatus of the present embodiment. (A) is a view showing the relationship between the image reading device and the book binding portion, and (b) is an exploded view of the AF floodlight 39. FIG. 5 is a diagram illustrating an example of a positional relationship when measurement light from an AF floodlight 39 is irradiated on a document surface. 6 is an orthographic view of the reading surface ABCD shown in FIG. 5, where (a) is a plan view seen from directly above, (b) is a right side view seen from the x direction, and (c) is a plan view. It is the front view seen from the y direction. It is a figure explaining the method for calculating a book reading start point. It is a figure which shows the state which set the ranging range wider than the reading range. It is the figure which showed the case where a solid object is larger than the reading range. In the three-dimensional object, when the length from the other end to the reading range is longer than the length outside the reading range, FIG. It shows a state where the spread book is within the reading range. When the spread book does not fit within the reading range, it is shown that it is read in two steps. 2 shows a display panel as a display device included in the image reading apparatus of the present embodiment. The state of the display panel at the time of reading a book is illustrated.

Explanation of symbols

1 Housing 2 Wall 39 AF floodlight

Claims (7)

A light source for irradiating the reading surface of the object with light;
An optical system for forming an optical path of reflected light from the reading surface;
Having an imaging means for performing imaging processing from the reflected light,
In the image reading apparatus for reading the image on the reading surface,
An image reading apparatus that measures the height of the reading surface from a read image and sets an image reading range based on the height information.   The image reading apparatus according to claim 1, wherein a measurement range for measuring the height is set wider than the reading range.   The image reading apparatus according to claim 1, further comprising a determination unit that determines whether the object is within the reading range based on the height information.   The image reading apparatus according to claim 3, further comprising a display unit that displays a result of the determination unit.   The image reading apparatus according to claim 4, wherein the display unit displays that the object is moved within the reading range.   5. The image according to claim 4, wherein when the object does not fall within the reading range, the display unit performs a display instructing to perform an operation of reading the image on the reading surface a plurality of times. Reader.   The image reading apparatus according to claim 1, wherein when the object is a book, a boundary between a fore edge and a printing plate of the book is detected based on the height information.

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