JP4913089B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus used for a copying machine or the like.

  There are roughly two types of image reading apparatuses that are used in copiers, scanners, facsimiles, and the like and read an entire image by scanning an image at a reading position using a one-dimensional imaging device. In general, the direction in which the one-dimensional imaging elements are arranged is called a main scanning direction, and the scanning direction is called a sub-scanning direction.

  One of the two types is a method of reducing and transferring the entire image in the main scanning direction onto the image sensor with a monocular lens, and is mainly used for reading the front surface in a copying machine. Yes. In this method, the image pickup element and the lens located on the original document side are usually fixed, only the mirror is moved in the sub-scanning direction, and the entire original document is scanned. In this method, since the depth of focus on the original side (referred to as depth of field) is as large as several millimeters, for example, 6 mm, the original can be read even if the original is not in close contact with the original reading surface of the copier. There are advantages. For example, this method is mainly used for the front surface reading operation of a copier because it has the advantage of being able to read without defocusing even when it cannot be brought into close contact with the original reading surface, such as a book binding. Has been. There are various patent documents derived from this method. For example, Patent Document 1 is cited (referred to as Conventional Method 1).

  The other of the above two methods is a method of dividing an image in the main scanning direction into a plurality of images and reading the image with a compound eye lens, and is usually called a contact image sensor. This method is used for a back side reading of a copying machine, a facsimile document reading, a banknote recognition sensor, a scanner for a personal computer, and the like, and is characterized by a small size. For example, Patent Document 2 discloses a conventional technique that is currently mainstream as an optical system of the contact image sensor. Here, as a compound eye lens (rod lens array in the literature), an array of a plurality of rod lenses having a refractive index distribution defined by a certain function in the radial direction is used. An image reading apparatus for obtaining an image is disclosed (referred to as Conventional Method 2).

  As another example of a typical system in the optical system of the contact image sensor, there is a system disclosed in Patent Document 3, for example. In this method, an image of a region corresponding to a cell is reduced and transferred by a lens provided for each cell divided in the main scanning direction, and formed on an image sensor. The image on the original surface is restored by synthesizing the output signals of the image sensors installed in each cell (referred to as conventional method 3).

  Patent Document 4 discloses a method of obtaining an erecting equal-magnification image using a compound eye mirror lens array, which is similar to Conventional Method 2 or Conventional Method 3 (referred to as Conventional Method 4).

  In Patent Document 5, the reading area is divided into odd-numbered areas and even-numbered areas, and the optical path of the imaging optical system is changed at the odd-numbered and even-numbered areas. A method of obtaining an erecting equal-magnification image on the surface has been disclosed (referred to as Conventional Method 5).

JP-A-10-308852 Japanese Patent Laid-Open No. 8-204899 JP-A-5-14600 JP-A-11-8742 JP-A-2005-37448

  The conventional method 1 has an advantage that the depth of field is large as described above, but there is a problem that the optical system becomes large. Further, in order to prevent the optical path from the document surface to the lens from changing when the mirror is moved, it is necessary to control the moving speed of a plurality of mirrors in the middle of the optical path. There is a problem.

  Although the conventional method 2 has the merit of being small and low cost, there are a problem that the depth of field is small and a problem that the chromatic aberration is large.

  Regarding the conventional method 3, when the depth of field is increased, the size of the apparatus increases, the problem that chromatic aberration increases, and the transfer magnification varies depending on the depth of field. When combining these images, there is a problem in that there is a mismatch in image overlay. For this reason, it is difficult to increase the depth of field.

  The conventional method 4 has an effect that there is no chromatic aberration because a mirror array in which a plurality of concave mirrors are arranged is used as the imaging optical element. However, since there is no description of the detailed arrangement regarding the diaphragm 17, the first mirror array 13, and the first mirror array 14, the image transfer magnification may change when the document 10 is greatly separated from the contact glass 12. It is done. As a result, the overlapping method of adjacent images is different, and it is considered that the image on the array boundary surface deteriorates, and it is difficult to obtain a large depth of field.

  Regarding the conventional method 5, the image is read from the oblique direction with the odd-numbered region imaging systems 11 to 41 and the even-numbered region imaging systems 12 to 42 with respect to the linear object 10. For this reason, when the position of the object 10 in the focal direction changes, the reading position is changed between the odd-numbered area and the even-numbered area, and there is a problem in that both images are shifted on the photosensitive medium 60 that is the imaging surface. . Further, the specification does not describe a specific configuration and effect of the telecentric imaging system. When the position of the object 10 in the focal direction changes, the transfer magnification at the focal position may change, and the way in which images are superimposed between the integer m-th and m + 1-th imaging systems is different and the image deteriorates. End up. Due to the above two problems, it is difficult for the conventional method 5 to obtain a large depth of field.

  The present invention has been made to solve the above-described problems, and is small in size and can be restored to a focused state even in an image outside the depth of focus range, that is, a substantially large object field. An object is to provide an image reading apparatus having a depth.

In order to achieve the above object, the present invention is configured as follows.
That is, an image reading apparatus according to an aspect of the present invention collects a top plate on which an original is placed, a light source that irradiates light on an imaged portion of the original, and scattered light of the light reflected by the imaged portion. An imaging optical system that illuminates and forms an image as a plurality of cells arranged in the main scanning direction, each of which is an independent optical system, and the cells are arranged in the first and second rows in the sub-scanning direction. An imaging optical system in which the cells are arranged in a staggered manner so as to complement each other in the main scanning direction, and the cells are arranged corresponding to the cells. A plurality of image sensor units that capture each image formed in the image, a memory that stores image information obtained from the image sensor unit, and the image information stored in the memory is restored for each image corresponding to the cell. And a processing device for creating a document image by combining them In the image reading apparatus, chief rays directed from the imaging target portion to the cells are parallel between the cells arranged along the main scanning direction in the same row of the first row and the second row. Between each cell arranged in one row and each cell arranged in the second row, the cell is inclined toward the gap between the first row and the second row. The image correction unit is arranged in the sub-scanning direction in the sub-scanning direction of each image information obtained from the imaging element unit corresponding to each cell arranged in the first column and the second column in the sub-scanning direction. A distance from the focal position to the imaged part in the focal direction is obtained, and the original image is created by correcting the image information based on the distance.

  According to the image reading apparatus of one aspect of the present invention, first, a plurality of cells are provided along the main scanning direction in two rows of the first row and the second row in the sub-scanning direction. Can be achieved. Further, the principal ray directed from the imaged part of the document to each cell arranged in the first row and the principal ray directed from the imaged part of the document to each cell arranged in the second column are represented by the first column and the above-described first ray. The processing apparatus was configured to have an image correction unit by inclining toward the gap with the second row. According to this configuration, even if a gap is generated between the focal position and the imaged part of the document in the focal direction, the imaged part is located outside the focal depth range of the optical system, and the image sensor part is blurred. Even in such a case, the processing apparatus can restore the blurred original image into a focused original image.

explain in detail. As described above, the chief ray of each cell in the first row and the second row is inclined. Therefore, when the focus position of each cell is on the top surface of the top plate and the imaged portion of the document is located in contact with the top surface, the image formed in each cell in the sub-scanning direction does not shift. On the other hand, when a gap is generated between the focal position and the imaged part of the document in the focal direction, the image formed in each cell in the sub-scanning direction is changed in the sub-scanning direction according to the gap distance. Deviation occurs.
The image correction unit obtains how much the adjacent images in the sub-scanning direction are deviated in the sub-scanning direction when the image information from each image sensor unit is restored to the original image by the processing device. The distance between the focal position and the imaged part of the document is obtained from the amount of deviation in the sub-scanning direction. The degree of blur in the focal direction of the image depends on the distance in the focal direction between the focal position of the cell and the imaged part of the document. Therefore, the image correction unit restores the blurred image obtained due to the imaging target portion being located outside the focal depth range of the optical system to the original image using the obtained distance.

Further, in the main scanning direction, the distance between the top plate and the imaged part of the document can be measured at a fine pitch corresponding to the number of cells for each cell boundary. Therefore, even for a wrinkled document or a document in the vicinity of a book binding, it is possible to correct image blur due to defocus for each fine region in the image.
As described above, according to the image reading apparatus in one aspect of the present invention, the image reading apparatus is small and can be restored to a focused state even with an image outside the depth of focus range, that is, has a substantially large depth of field. A device can be obtained.

  An image reading apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals.

Embodiment 1 FIG.
Hereinafter, an example of the image reading apparatus according to Embodiment 1 will be described with reference to FIGS.
The image reading apparatus 201 of the present embodiment is broadly divided into an imaging optical system 1, a light source 2, a top plate 3, imaging element units 41, 42,..., A memory 5, and an image correction unit 61. And a processing device 6.
In these components, the light source 2 is disposed in the vicinity of the document 7 which is an example of an object to be read, and the imaging optical system 1 is disposed so that the light reflected from the document 7 can enter. In addition, an image pickup element 41 and the like are appropriately arranged corresponding to the imaging optical system 1. Such an image reading apparatus 201 reads an image of the document 7 along the main scanning direction (X direction) 211 and further scans the document 7 in the sub-scanning direction (Y direction) 212 orthogonal to the main scanning direction 211. Then, all images on the document 7 are read. The document 7 is an object to be read on which a sentence, a document, a photograph, or the like is displayed, or an object to be read such as a banknote, and is used as a basis for printing, authentication, or used as an electronic file. It corresponds to what is done. In FIG. 1, the document 7 is not shown for clarity.

  The document 7 is placed on the top plate 3 as a document placing member. The top plate 3 is made of a transparent body and is generally a glass plate. For example, the illumination light source 2 such as a fluorescent lamp or an LED is disposed below the top plate 3 at a position where the reading of the document 7 is not hindered, and the imaged parts 31 and 32 existing at the reading position on the document 7. ,... Are irradiated with an illumination light beam 221. In FIG. 1, the light source 2 is disposed only on one side of the imaging optical system 1 in the sub-scanning direction 212, but is not limited thereto, and may be disposed on both sides.

  In the drawing, the imaged parts 31, 32,... Are shown surrounded by a strip-like frame for ease of explanation and visual understanding, but there is no particular structure. For the sake of explanation, the portion where the imaged portions 31, 33,... Are arranged along the main scanning direction 211 is defined as a reading line 8, and the portion where the imaged portions 32, 34,. To do.

  The imaging optical system 1 is an imaging optical system that condenses the scattered light of the illumination light beam 221 of the light source 2 reflected by the image pickup units 31, 32. The imaging optical system 1 has a plurality of cells 11, 12,. Each of the cells 11, 12,... Is an independent imaging optical system, and a plurality of cells are arranged in the main scanning direction 211. Further, in the sub-scanning direction 212, the cells 11, 12,... Are arranged in two columns, a first column 215 (series 1) and a second column 216 (series 2). Here, the cells 11, 13, 15,... Belong to the first column 215, and the cells 12, 14,. In addition, the cells arranged in the same row are arranged such that the light rays from the original 7 toward the cells 11, 12,... Is provided so that the optical axes 11a, 13a, ... of the cells 11, 13, ... belonging to the first column are parallel to each other, and the cells 12, 13 belonging to the second column, The cells 12, 14,... Are provided so that the optical axes 12a, 14a,. Further, the first row 215 and the second row 216 are arranged so that the formed image can be complemented between the cells 11 and 12 in the sub-scanning direction 212, between the cells 12 and 13, between the cells 13 and 14,. The cells 11, 12, 13,... Are arranged in a staggered manner in the main scanning direction 211.

  On the other hand, in the sub-scanning direction 212, in the first embodiment, the optical axes of the cells 11, 12, 13,... Are inclined with respect to the top plate 3 as shown in FIG. That is, the optical axes 11a, 13a,... In the cells 11, 13,... Belonging to the first column 215 and the optical axes 12a, 14a,. The cells 11, 13,... In the first row 215 and the cells 12, 14,... In the second row 216 are arranged in a state inclined toward the gap between the 215 and the second row 216. Specifically, in the present embodiment, the cells 11, 13,... Belonging to the first column 215 are inclined around the X axis (main scanning direction 211) at a − (negative) set angle, and the second column 216 is. Are inclined at a + (positive) set angle around the X axis. In FIG. 3, the cell 13 is shown as a representative for the first row 215 and the cell 14 is shown as a representative for the second row, and the optical axis L1 of the cell 13 and the optical axis L2 of the cell 14 are the top surface of the top plate 3. The case of crossing at 3a is illustrated.

The arrangement and optical path of the optical system elements constituting each cell 11, 12, 13,.
(A) of FIG. 2 shows the imaging optical system elements of the cells 11, 13, 15,... Provided in the first column 215 in the main scanning direction 211, and the main optical path, and (b) of FIG. FIG. 2 is a diagram showing imaging optical system elements of cells 12, 14, 16,... Provided in a second row 216 and main optical paths in the main scanning direction 211. FIG. 3 is a diagram showing imaging optical system elements and main optical paths in a state where the cells 13 and 14 are overwritten in the sub-scanning direction 212.

  As shown in FIG. 2, each cell 11, 12, 13,... Has the same configuration, and here, the cell 11 is described as an example. The cell 11 includes a first lens 100 that is an example that functions as a first optical element, an aperture 101 that is an example that functions as a diaphragm, and a holder 103 that holds them.

The first lens 100 is disposed substantially at the center of the cell 11 in the direction of the optical axis 11a in the cell 11, and is a convex lens as shown in the present embodiment.
The aperture 101 supports the first lens 100 on both sides of the first lens 100 in a direction orthogonal to the optical axis 11 a, and has an opening at the center of the first lens 100. Therefore, the scattered light of the illumination light beam 221 of the light source 2 reflected by the image pickup unit 31 enters the first lens 100 through the opening of the aperture 101 and is emitted from the first lens 100.

.. Are arranged on the substrate 4 corresponding to the respective cells 11, 12, 13,. In other words, the image sensor sections 41, 43,... Are arranged corresponding to the cells 11, 13,... Belonging to the first column 215, and the image sensor sections 42 corresponding to the cells 12, 14,. , 44,... Are arranged.
Each of the imaging element units 41, 42,... Is configured by arranging a plurality of light receiving units made of, for example, a CCD or the like in the main scanning direction 211, and further arranging a plurality of the light receiving units in the main scanning direction 211. These are arranged in a plurality of rows in the sub-scanning direction 212.
Therefore, light rays that have been reflected and scattered from the original and passed through the cells 11, 12, 13,... Of the imaging optical system 1 are incident on the image sensor units 41, 42,.

  As shown in FIG. 2, in this embodiment, a document image passing through each of the cells 11, 12, 13,... Forms a reverse image on the corresponding image sensor 41, 42,. The transfer magnification may be larger than 1 or reduced smaller than 1, but if it is set to the same magnification, there is a merit that a sensor having a generally distributed resolution can be used.

The memory 5 temporarily stores image signals in the imaged parts 31, 32,... Of the document 7 formed on the image sensors 41, 42,.
The processing device 6 having the image restoration unit 61 reads the image signal from the memory 5 and restores the images of the imaged units 31, 32. The processing device 6 including the image restoration unit 61 will be described in detail below. The memory 5 and the image processing device 6 are illustrated as separate bodies in FIG. 1, but may of course be arranged integrally on the same substrate.

Next, taking a document such as a book as an example, the operation of the image reading apparatus 201 of the present embodiment will be described, and one of the features of the image reading apparatus 201 is that it has a large depth of field. It demonstrates using FIG.2 and FIG.3, and also demonstrates the processing apparatus 6. FIG.
As shown in FIG. 2, an original 7 whose position in the focal direction (Z direction) 213 changes in each cell 11, 12, 13,... Arranged along the main scanning direction (X direction) 211 is placed on the top 3. Assume that it is placed. That is, in the main scanning direction 211, the position of the focal direction 213 on the imaging surface of the document 7 changes. Further, as shown in FIG. 3, the area where the reading ranges of the cell 13 and the cell 14 overlap, that is, the height position of the document surface at the focal position of each cell is 71.

  Here, the case where each cell 11, 12, 13, ... is designed so that the upper surface 3a of the top plate 3 may become a focus position (just focus) is demonstrated. When image blur correction is not performed, the depth of field of the image reading apparatus 201 according to the present embodiment is almost determined by the depth of field of the cell. The depth of field of the cell is determined by the design of the optical system in the cell. The depth of field is substantially determined by the F value of the optical system. In order to increase the field of view of one cell, it is necessary to sufficiently correct aberration by making the lens provided in the cell an aspherical shape or using a plurality of lenses. For example, when a resolution of 600 dpi is required, an approximate value of ± 1 mm is obtained with F value = 10, and a depth of field of approximately ± 2 mm is obtained with F = 20. 2 and 3, the top surface 3a of the top plate 3 is illustrated as being just focused, but this is not necessarily the case. For example, in the optical system of F = 10, if the top plate 3 is arranged so that the focus is just 1 mm above the top plate top surface 3a, a depth of field of ± 2 mm can be sufficiently used.

Hereinafter, as a specific example, a case where F = 10, a depth of field of about ± 1 mm, and a focal position on the top surface 3a will be described. That is, the depth of field by only the optical system is in the range of 1 mm from the top surface 3a.
As shown in FIG. 3, the light beam emitted from one point on the position 71 and incident on the cell 13 is not condensed at one point on the light incident surface of the image sensor section 43 and causes defocusing. Similarly, the light rays incident on the cell 14 are not condensed at one point on the light incident surface of the image pickup device portion 44, and cause defocusing. If the distance in the Z direction between the upper surface 3a of the top plate 3 and the document position 71 is within 1 mm, the defocus is within an allowable range. In other words, it can be said that the radius of the point image from the document position 71 is within the radius of the allowable circle of confusion.

  On the other hand, if the distance between the top surface 3a of the top plate 3 and the document position 71 in the Z direction exceeds 1 mm, the spread of the point image (point image distribution function) exceeds the radius of the permissible circle of confusion, and the target resolution is reduced. It will not be achieved. The transfer image of the document 7 placed at a position exceeding 1 mm becomes a blurred image, and there is an image blur correction processing technique for restoring the original image from the blurred image by image processing. When executing the image processing of the image blur correction, if the point spread function is known, the image blur correction processing can be executed more advantageously than when it is unknown.

  The point spread function is uniquely determined by the position of the document position 71, can be actually measured, and can be obtained by calculation by ray tracing simulation. That is, if the distance between the top surface 3a of the top 3 and the document position 71 is known, the point spread function can be known, and the image blur correction process becomes easy. If image blur correction processing can be performed and the resolution after image processing increases, an in-focus image can be obtained beyond the depth of field of 1 mm determined only by the optical system. Will have a depth of field.

  In the present embodiment, two images in the sub-scanning direction 212 are restored when images obtained in different series, that is, the cells belonging to the first column 215 and the second column 216 and adjacent to each other, for example, the cell 11 and the cell 12 are restored. The distance in the focal direction (Z direction) from the upper surface 3a of the top plate 3 to the document position 71 can be calculated from the shift amount when the images are aligned. This will be described below.

  4 is an enlarged view of only the vicinity of the top plate shown in FIG. 3, and only the optical axes L1 and L2 are shown for light rays. A second position 72 on the document surface is also added. The optical axis L1 is the optical axis of the cell 13 belonging to the first column 215, and the optical axis L2 is the optical axis of the cell 14 belonging to the second column 216. In FIG. 4, the two optical axes L <b> 1 and L <b> 2 are shown intersecting at the top surface 3 a, but it is not always necessary to intersect at the top surface 3 a. The crossing may be performed at a position away from the upper surface 3a by a distance, or may be crossed below the top plate upper surface 3a. It is important that the two optical axes are not parallel in the sub-scanning direction 212. In the example shown in FIG. 4, the optical axes L <b> 1 and L <b> 2 are inclined at an angle of ± θ with respect to the vertical line of the top 3.

  On the top surface 3a, the distance between the two optical axes L1 and L2 in the Y direction, that is, the sub-scanning direction 212 is zero, but the two optical axes L1 and L2 at a position 71 that is separated from the top surface 3a by a distance Δz1 in the Z direction. The distance ΔY1 in the Y direction can be expressed as 2 × Δz1 × tan θ. That is, when the document 7 is positioned on the top surface 3a, the positional deviation in the sub-scanning direction 212 (Y direction) of each image obtained by the image sensor unit 43 and the image sensor unit 44 is zero. 7 is present at the position 71, the two images obtained by the image sensor unit 43 and the image sensor unit 44 are displaced by ΔY1 in the sub-scanning direction 212.

  In the present embodiment, when the image is restored, the processing device 6 obtains the deviation amount ΔY1 that is the interval, and further calculates the distance Δz1 from the top surface 3a to the document position 71. Further, the processing device 6 performs image blur correction processing based on the obtained distance Δz1. Thereby, the image reading apparatus 201 of the present embodiment has an effect that it can have a substantially large depth of field exceeding the depth of field of 1 mm which the optical system has.

  The image restoration process executed by the processing device 6 having the image correction unit 61 will be described in more detail. Here, in order to simplify the description, an image reading apparatus including four cells 0 to 3 shown in FIG. 5 will be described as an example. It is assumed that cell 0 and cell 2 belong to the first column 215, and cell 1 and cell 3 belong to the second column 216.

  The procedure of the image restoration process is shown in FIG. The original image read while moving (scanning) the imaging optical system 1 in the sub-scanning direction 212 in step 1 is stored in the frame memory 5 in step 2 after finishing black correction, white correction, and the like. Is done. Since the image read for each cell is an inverted image, in step 3, the images are rearranged so as to be in the same orientation as the original. After that, in step 4, the joining position between the images of adjacent cells is detected in line units, and the images are joined at the detected position. At that time, as a step 5, smoothing processing of the joints is performed so that the joints of the images are not noticeable. In step 6, the original image restored in this way is output as a reading result.

  In the present embodiment, the data stored in the frame memory 5 is once sorted, but the data order is changed by changing the address when data is read from the memory 5. You may do it. Further, the order of data may be changed by storing data for one line in the line memory at the time of reading from the image sensor unit, and outputting the data with a delay of one line from the last stored data. It is not always necessary to perform rearrangement processing in the frame memory 5. Further, instead of the frame memory 5, it is possible to output the restored image sequentially using a memory having the minimum number of lines necessary for processing. Thus, the memory 5 shown in FIGS. 1 and 5 is not limited to a frame memory.

As shown in FIG. 7, the image combining process executed in step 4 will be described in the case where the imaged part of the document 7 exists at the focal position. Images obtained from the cells 0 to 3 are shown in FIG. It is assumed that the rearrangement process has already been completed.
The cells 0 to 3 and the image sensor portions corresponding to the cells 0 to 3 are arranged so as to partially overlap each other in the main scanning direction 211. Therefore, the same image is included at the end of each image acquired between adjacent cells. Using this overlappingly read area, a corresponding position between images by adjacent cells is obtained. Based on the result, the original image is restored by connecting the two images. Detection of the corresponding position is performed in each line at the end of each cell.

  First, as shown in FIG. 9, the line L0 is selected from the images obtained in the cell 0. An area of N × M pixels centered on the pixel (xa, ya) on the selected line L0 is defined as an area A. Vector data A = {a0, a1,..., An} is created from the luminance values of the images included in the region A. Similarly, a region B of N × M pixels centering on the pixel (xb, yb) in the cell 1 adjacent to the cell 0 is set, and the vector data B = {b0, b1,..., bn} are created.

  From these vector data A and B, the degree of coincidence d (xb, yb) of the image between the region A and the region B is obtained by the equation (1). The degree of coincidence d decreases as the two vector data are closer (similar). That is, the smaller the matching degree d, the higher the matching degree between the images of the area A and the area B.

  The degree of coincidence d (xb, yb) is calculated while changing the position of the region B in the x and y directions on the cell 1 image, and the position (xb_min, yb_min) where the degree of coincidence d is smallest is obtained. Since the region B having the smallest coincidence d is the region most coincident with the region A, the center pixel (xa, ya) of the region A on the image of the cell 0 and the center of the region B on the image of the cell 1 The pixels (xb_min, yb_min) are pixels obtained by reading the same part of the document. Therefore, the line L1 of the cell 1 connected to the line L0 of the cell 0 is obtained by Expression (2).

L1 = L0 + (ya−yb_min) Equation (2)

  Similarly, the line L2 of the cell 2 connected to the line L1 of the cell 1 and the line L3 of the cell 3 connected to the line L2 of the cell 2 are obtained, and the original data for one line is restored by connecting the line data. When connecting line data, adjacent cell images may be connected with the central pixel in the regions A and B as a boundary. However, since the joint portion may be conspicuous, smoothing processing may be performed in which the luminance value of the corresponding pixel in the adjacent cell image is added with a predetermined weight.

  FIG. 10 shows an example of the smoothing process when the line L0 of the cell 0 and the line L1 of the cell 1 are combined. In the figure, the pixel a43 on the line L0 corresponds to the pixel b2 on the line L1. Similarly, the pixel a44 on the line L0 and the pixel b3 on the line L1 correspond to the pixel a45 on the line L0, the pixel b4 on the line L1, and the pixel a46 on the line L0 and the pixel b5 on the line L1 correspond to each other. A combined result is obtained by adding a value obtained by multiplying each pixel value of the line L0 by the coefficient K0 and a value obtained by multiplying each pixel value of the line L1 by the coefficient K1. The coefficients K0 and K1 are coefficients for performing the weighting, and are set to be 1.0 when the coefficient values of the corresponding pixel positions are added. Each coefficient is 0.0 from the cell edge to the front of the smoothing region, gradually changes from 0.0 to 1.0 in the smoothing region, and 1.0 in the other regions. Yes. By such weighted addition, the images of adjacent cells can be joined together without making the joints conspicuous.

  When the connection for one line from the cell 0 to the cell 3 is completed, the process returns to the cell 0 again, selects the line L0 + 1 that is the next row of the previously selected line L0, and performs the same processing as the previous time. This process is repeated until the last line to restore an image for one frame.

  As shown in FIG. 7, when the imaged portion of the document 7 exists at the focal position of each cell, each cell of the series 1 and the series 2 reads the same imaged portion of the document 7 at almost the same timing. . Therefore, the lines L0, L1, L2, and L3 are almost the same line when counted from the top of the read image. Even if there is a deviation, it is considered that this is due to an error in attaching the cell or the image sensor section.

  On the other hand, as shown in FIG. 11, when the imaged part of the document 7 is at a position 1 mm away from the focal position, each cell belonging to the first column 215 (series 1) and the second column (series 2). 0 to 3 are misaligned at the position where the document 7 is read. For example, when the imaging optical system 1 moves in the sub-scanning direction 212 and reads the position of P on the document surface, the cell belonging to the series 1 first reads the position of P, and after a while, the cell belonging to the series 2 Reads the position of P. Therefore, as shown in FIG. 12, the read image by the cells belonging to the series 2 is shifted downward in the drawing as compared with the read image by the cells belonging to the series 1. Even in such a case, it is possible to restore the original document image without deviation by performing the combining process while obtaining the matching position between adjacent cell images in units of lines.

  In the above description, the focus position is set to the upper surface 3a of the top plate 3 as an example. Of course, the focal position may be set to a position other than the upper surface 3a depending on the configuration of the imaging optical system 1. It is. Therefore, the focal position of the imaging optical system 1 including the cells 11, 12, 13... Is known in advance and stored in the processing device 6. The operations described below are also executed by the processing device 6, particularly the image correction unit 61 included in the processing device 6.

At this time, the shift between the line N and the line N + 1 connected between the adjacent cell N and the cell N + 1 corresponds to the distance from the focal position of the cell N and the cell N + 1 to the document surface. The document surface corresponds to a portion of the document 7 where the imaged parts 31, 32,.
Strictly speaking, the read image of each cell is originally deviated due to the mounting accuracy of each cell and the image sensor section. Therefore, a test pattern document such as an oblique lattice is read in advance at the focal position, and an initial deviation amount between cells is obtained and stored from the read image. The distance Δz to the true original surface can be obtained by subtracting the initial deviation amount from the read original image as an offset.

  At the time of combining the cell images, the distance to the document surface can be obtained at the connecting portion of each line. Therefore, distance information is obtained for each line in the sub-scanning direction 212 and for each cell interval in the main scanning direction 211. Since the blur amount of the image can be estimated from this distance information, a highly accurate blur correction process can be performed.

  The combined position (distance information) can be obtained in units of lines, but it is not always necessary to detect the combined position in units of lines and combine the images in units of lines. For example, the coupling position may be detected at fixed line intervals, and the positional deviation may be distributed and corrected within the fixed line range. As shown in FIG. 25, a description will be given of a case where the coupling position is detected with the cell 0 as a reference at intervals of K lines.

  Regarding cell 0, the number of lines between the M-th and M + 1-th combined positions is K lines, but for other cells, the number of lines may be different for each cell. The image for K lines is combined while absorbing the difference. As a method of absorbing the difference, line data may be deleted / inserted for each cell, or enlargement / reduction processing may be performed so that the number of lines of all cells is the same. However, if the line data is deleted, one line disappears from continuously read images, so that portion may become conspicuous. When deleting line data, it is better to perform processing for correcting the surrounding image. Also, when inserting line data, any of the line data may be used repeatedly, but a natural image can be obtained by generating interpolation data using the surrounding image.

The blur characteristic of the image can be grasped by a point spread function representing the extent of the image obtained when the point is imaged. FIG. 13 schematically shows a blurred image obtained when a point image is captured by a camera and a point spread function obtained from the blurred image.
If the blurring method of the image is known, the image before blurring can be restored from the blurry image by performing reverse conversion on the blurry image. That is, when the image F becomes the blurred image G by the function H, the original image F can be restored from the blurred image G by the inverse transformation shown in Expression (3).

F = G × H- ¹ Formula (3)

For example, blurring occurs because the luminance values of the peripheral pixels of the image before blurring are mixed with the luminance values of the image before blurring. Considering this as an integral operation, an image before blur can be obtained by performing a differential operation that is the reverse operation.
The point spread function changes depending on how the image is blurred, that is, how much the subject is displaced from the focal position. Therefore, the point spread function is measured in advance according to the distance from the focal position to the original surface, and the inverse function to be applied is selected according to the distance from the focal position to the original surface. For example, an inverse function having different weighting applied to the target pixel range and the luminance value of each pixel may be selected according to the distance.

  The distance from the focal position to the document surface can be obtained only at the joint between adjacent cells. The distance from the focal position at the pixel between the joints to the document surface is the distance from the focal position at one joint to the document surface, and the distance from the focal position at the other joint to the document surface. It may be estimated by linear interpolation.

  As described above, according to the image reading apparatus 201 of the present embodiment, the processing apparatus that tilts the optical axis of each cell arranged in the sub-scanning direction 212 with respect to the top 3 and has the image correction unit 61. 6, even when the imaged part exists outside the depth of field of the imaging optical system 1 and the image becomes blurred, the image can be restored to the focused state. Can have a large depth of field. Further, by providing a plurality of cells in the main scanning direction 211, the image reading apparatus 201 can be downsized.

Embodiment 2. FIG.
Next, the image reading apparatus 202 according to the second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, the optical system of each cell 11, 12,... Constituting the imaging optical system 1 constitutes a telecentric optical system on the document 7 side. The other basic configuration of the image reading apparatus 202 is the same as the configuration of the image reading apparatus 201 described above. That is, the image reading apparatus 202 according to the second embodiment also includes the image processing apparatus 6 including the memory 5 and the image correction unit 61 described above.

In FIG. 14, the cells 11, 13,... Belonging to the first column 215 and the image sensor units 41, 43,... Corresponding to these cells 11, 13,. .., And the image sensor sections 42, 44,... Corresponding to these cells 12, 14,. Further, the memory 5 and the image processing apparatus 6 are shown only in FIG. 14B, but the substrate 4 shown in FIGS. 14A and 14B is the same, and of course the image sensor section. 41, 43,... Are also connected to the memory 5 and the image processing device 6.
Hereinafter, only differences from the first embodiment will be described.

  As described above, the image reading apparatus 202 of this embodiment has a telecentric optical system on the document 7 side. The cell 11 will be described as a representative. The cell 11 includes a first lens 100, an aperture 101, a second lens 102 corresponding to an example of a second optical element, and a holder 103 that holds them. In contrast to the configuration of the cell 11 in the image reading apparatus 201 of the first embodiment, in the image reading apparatus 202 of the present embodiment, the first lens 100 is disposed at the end of the cell 11 on the side of the document 7 and the second lens 102 is provided. The aperture 101 is arranged at the end of the cell 11 on the imaging element unit 41 side, and is arranged at the back focal position of the first lens 100 between the first lens 100 and the second lens 102. With this configuration, the cell 11 realizes a telecentric optical system on the document 7 side. As described above, the other cells 12, 13,... Have the same configuration.

  Each cell 11, 12, 13,... Has the above-described configuration, but each cell 11, 12, 13,... Is arranged in the same manner as in the case of the image reading apparatus 201 of the first embodiment. Has been. Is provided so that the optical axes 11a, 13a, ... of the cells 11, 13, ... belonging to the first column are parallel to each other, and the cells 12, 13 belonging to the second column, The cells 12, 14,... Are provided so that the optical axes 12a, 14a,. Further, the cells 11, 12, 13,... In the first column 215 and the second column 216 are arranged in a staggered manner in the main scanning direction 211. Further, the optical axes 11a, 13a,... In the cells 11, 13,... Belonging to the first column 215 and the optical axes 12a, 14a,. The cells 11, 13,... In the first row 215 and the cells 12, 14,... In the second row 216 are arranged in a state inclined toward the gap between the 215 and the second row 216.

The image reading apparatus 202 configured as described above can perform the same operation as that of the image reading apparatus 201 of the first embodiment.
That is, based on the same principle as described in the first embodiment, the distance Δz from the focal position to the document surface is calculated from the shift amount ΔY in the sub-scanning direction 212 of two images obtained from adjacent cells. Can do. By using the distance Δz, blur correction of the image can be performed and the substantial depth of field can be increased. In the present embodiment, the focal position is also located on the upper surface 3a of the top plate 3 as an example.
In addition, the above-described effects achieved by the image reading apparatus 201 according to the first embodiment can also be achieved by the image reading apparatus 202 according to the second embodiment.

Since each cell 11, 12, 13,... Is a telecentric optical system on the document 7 side, in this embodiment, even if the distance Δz fluctuates, the transfer magnification of the image with respect to the image sensor portions 41, 42,. It does not change. Since the transfer magnification of the image does not change, processing for enlarging or reducing the size of the image to a reference size becomes unnecessary, and high-speed signal processing is possible. Therefore, it is possible to greatly reduce the load of image restoration processing for combining the images of the cells 11, 12, 13,.
Further, if the optical axis of each cell 11, 12,... And the top plate 3 are perpendicular to the main scanning direction 211, the image of each cell 11, 12,. Does not move at all. Also in the sub-scanning direction 212, the transfer magnification does not change due to the change in the distance Δz, and each image only moves in the sub-scanning direction 212. Therefore, image processing in the main scanning direction is not necessary, and correction for shifting in the sub-scanning direction 212 by the amount of positional deviation between two images adjacent in the sub-scanning direction 212 may be performed at the time of image composition. Therefore, there is an effect that signal processing can be performed at a higher speed than in the case of the first embodiment, or image restoration can be performed by a low-cost processing device.

Embodiment 3 FIG.
FIG. 16 shows an example of the image reading device 203 in the third embodiment. The cells 11, 12,... Are the same as those in the above-described second embodiment. In the image reading apparatus 203 according to the third embodiment, the optical path is bent in the horizontal direction between the first lens 100 of the cells 11, 13,... Belonging to the first row 215 and the top plate 3. .. Corresponding to an example of a bending member that bends the optical path in the horizontal direction between the first lens 100 and the top plate 3 of the cells 12, 14,... Belonging to the second row 216. A second folding mirror 112 is provided. The cells 11, 13,... Belonging to the first column 215 are folded in the opposite directions, and the cells 12, 14,.
The other configuration of the image reading apparatus 203 in the third embodiment is not different from that of the image reading apparatus 202.

  The image reading device 203 having the above-described configuration can achieve the same operations and effects as the image reading device 202 of the second embodiment, and further, by providing the folding mirrors 111 and 112, the image reading device Compared with the apparatus 202, the thickness of the apparatus in the Z direction can be suppressed, and a small image reading apparatus can be configured.

Embodiment 4 FIG.
Next, an example of the image reading device 204 according to the fourth embodiment of the present invention will be described with reference to FIGS.
FIG. 17 shows the internal structure of the optical system portion of the image reading apparatus 204 in which a plurality of cells are arranged. In addition, in order to avoid the complexity of illustration, illustration of the illumination light source 2, the top plate 3, etc. is abbreviate | omitted. FIG. 18 is a diagram showing only the optical elements of one cell extracted from the configuration shown in FIG. FIG. 19 is a cross-sectional view of the image reading apparatus 204 along the sub-scanning direction 212 with the main scanning direction 211 perpendicular to the paper surface.

In each of the second and third embodiments described above, the first lens 100, the aperture 101, and the second lens 102 constituting each cell 11, 12, 13, 14,... Are arranged along a straight line, and the first lens 100 is arranged. Between the aperture 101 and the second lens 102, the optical axis passing therethrough is in a straight line without being bent.
On the other hand, the fourth embodiment shows the form of the cells 11, 12, 13, 14,... More suitable for the actual configuration of the image reading apparatus.

  The cells 11, 13,..., The cells 12, 14,... Are arranged along the first column 215 and the second column 216, .., 12, 13, 14,... Form a telecentric optical system on the document side, and the cells 11, 13,. .. Corresponding to the cells 11, 12, 13, 14,... 44,... And the provision of the memory 5 and the processing device 6 are the same in the fourth embodiment. Therefore, the image reading apparatus 204 according to the fourth embodiment can achieve the above-described effects that the image reading apparatus 202 according to the second embodiment exhibits.

  The difference between the fourth embodiment and the second embodiment will be specifically described. In the image reading device 204 according to the fourth embodiment, the members corresponding to the first lens 100 and the second lens 102 are reflective condensing elements. The element is composed of a concave mirror as an example. Furthermore, the optical path is bent by these reflective condensing elements. Further, a third bending corresponding to an example of a bending member is provided between the concave mirror corresponding to each second lens 102 in each cell 11, 12, 13,... And the imaging element portions 41, 42, 43,. A mirror 113 is provided.

  In the fourth embodiment, both the first lens 100 and the second lens 102 are configured as concave mirrors, and the image reading apparatus can be made compact in the Z direction and the sub-scanning direction 212. However, the present invention is not limited to this configuration, and at least one of the first lens 100 and the second lens 102 may be configured by a reflective condensing element.

  As described above, the concave mirror, which is an example of the reflective condensing element, performs the same function as the first lens 100 and the second lens 102 described in the second and third embodiments, but has a different form. . In the following description, an example corresponding to the first lens 100 and corresponding to the example of fulfilling the function of the first optical element is referred to as the first concave mirror 100A, and corresponding to the second lens 102 and fulfilling the function of the second optical element. Is replaced with the second concave mirror 102A.

Further, the image reading device 204 will be described in detail.
A light beam reflected and scattered from the original 7 irradiated by the illumination light source 2 enters the cell 11 or the like. Here, the optical path and configuration of only one cell, for example, the cell 11, will be described in detail with numerical values. The reading width in the main scanning direction 211 of one cell 11 is 10 mm. The tilt angle of the optical axis with respect to the top plate 3 in the sub-scanning direction 212 is 5 °. That is, a light beam having a light beam having an angle of 5 ° in the sub-scanning direction from the document surface as a main light beam contributes to image formation. The light beam is bent in the optical path by the first folding mirror 111. In FIG. 19, the light beam is deflected in a direction that forms an angle of 8 ° with respect to the Y axis.

  The first concave mirror 100A has a focal length f = 20 mm. The distance from the document surface to the first concave mirror 100A is designed to be approximately 20 mm, and the light beam reflected by the first concave mirror 100A is collimated. An aperture 101 is set at a position 20 mm from the first concave mirror 100A along the optical axis optical path. Since this is equal to the focal length of the first concave mirror 100A, this cell becomes a telecentric optical system on the document side.

  The aperture diameter of the aperture 101 determines the brightness and depth of field of the optical system. Here, the aperture diameter of the aperture 101 is set to φ1 mm. That is, the F value of the optical system is 20. At this time, if the arrangement of the optical components in the entire cell and the first concave mirror 100A and the second concave mirror 102A are optimized and designed with an aspherical shape or the like, a sufficient depth of field of ± 2 mm, that is, 4 mm can be obtained. be able to.

  The light beam that has passed through the aperture 101 is collected by the second concave mirror 102A, passes through the third folding mirror 113, and forms an image on the image sensor section 41. Here, if the second concave mirror 102A is also set to f = 20 mm, a reverse image with a transfer magnification of 1 can be obtained. The method for restoring the inverted image is as described in the first embodiment.

  In this example, since the optical path length from the aperture 101 to the second concave mirror 102A and the distance from the second concave mirror 102A to the image sensor 41 are both set to 20 mm, not only on the document side but also on the image side. It is a telecentric optical system. Thus, by forming a telecentric optical system on the image side as well, there is an effect that the imaging magnification of the imaging element unit 41 and the like becomes constant regardless of the installation position in the focal direction.

  As described above, in this embodiment, since the concave mirror is used for the first concave mirror 100A and the second concave mirror 102A, there is another advantage that chromatic aberration does not occur. In particular, in an optical system having a large depth of field, which is a feature in each embodiment, chromatic aberration is likely to be a problem, but chromatic aberration can be avoided by forming a reflective optical system as in this embodiment. . Further, because of the reflecting mirror, the optical path can be folded, and there is a great advantage that the entire optical system can be made compact in the Z direction and the sub-scanning direction 212.

  In the above-described example, the optical path length from the document 7 to the image pickup device unit 41 is 80 mm. That is, if the bending mirrors 111 and 113 are not provided and the concave mirrors such as the first concave mirror 100A and the second concave mirror 102A are not used, the thickness of the entire optical system in the Z direction is about 80 mm. However, since the optical path is folded, the thickness of the optical system in the Z direction can be reduced to about 23 mm.

  Further, since the transfer magnification is 1, there is an advantage that the existing image pickup device portion can be used and the cost can be reduced. In other words, if the optical system is a reduction system, the resolution of the image obtained by the resolution of the image pickup device section itself deteriorates unless one pixel unit of the image pickup device section is reduced in accordance with the reduction magnification. If the resolution of an existing contact type image sensor that captures an erecting equal-magnification image is 600 dpi, a resolution of 600 dpi can be achieved by diverting the image sensor unit as it is.

  Further, when the transfer magnification is 1, the same member can be used for the first concave mirror 100A and the second concave mirror 102A. In particular, as in this embodiment, if the optical system is telecentric on both the document side and the image side, it is sufficient even if the shapes of the first concave mirror 100A and the second concave mirror 102A are the same in terms of lens optimization design. It is possible to design an optical system having imaging conditions with a high resolution. By using the same member, there is an effect that the cost can be reduced.

Next, a configuration in which a plurality of cells 11 and the like are combined will be described.
The optical axis tilted by + 5 ° around the X axis from the original surface acts on the cells 11, 13,... In the first row 215, and the X axis from the original surface acts on the cells 12, 14,. An optical axis tilted by -5 ° acts around. The interval in the sub-scanning direction 212 in each of the k-th and k + 1-th cells, that is, the interval between the reading lines 8 and 9 is 9 mm. Further, the distance between cells in the same column, that is, the distance between each of the kth and k + 2 cells is 18 mm. Since the reading width of one cell is 10 mm, the overlapping width of the reading area between adjacent cells, that is, the k-th and k + 1-th cells is 1 mm. A width of 1 mm and 600 dpi in the main scanning direction 211 means about 24 pixels, which is sufficient for image synthesis between adjacent cells as described in the second embodiment.

  As shown in FIG. 19, the optical paths of the first half of the cells 11, 13,... In the first column 215 and the cells 12, 14,... In the second column 216, that is, the optical paths from the document surface to the aperture 101 are folded. Yes. In three dimensions, the optical paths do not overlap. Since the optical paths are configured to be folded in this way, the overall size of the optical system is made compact.

  Further, in this embodiment, the in-focus position on the original side is designed at a position 73 1 mm from the top surface of the top plate, and further, the reading line 8 of the cells 11, 13,. The reading lines 9 of the cells 12, 14,... Are designed to intersect at a position 73. As described above, since the optical system itself has a depth of field of ± 2 mm, sufficient resolution can be obtained from the top surface of the top 3 to the position 75 of 3 mm. In other words, the depth of field of the image reading device 504 is 3 mm from the top surface of the top plate. The resolution is better at the in-focus position, even though it is within the depth of field. However, when it is desired to increase the depth of field, the depth of field is reduced by lowering the position of the top 3 so that the in-focus position is located at a position 2 mm from the top surface of the top 3. It can be increased to 4 mm from the upper surface of the top 3.

  The reading line 8 of the cells 11, 13, ... in the first column 215 and the reading line 9 of the cells 12, 14, ... in the second column 216 are moved in the sub-scanning direction 212 as the position of the document surface moves away from the position 73. Go away. As described in the second embodiment, this is because the optical system is telecentric on the document side, the transfer magnification does not change in the main scanning direction 211 and the sub-scanning direction 212, and the optical axis is perpendicular to the main scanning direction 211. Therefore, the deviation of the reading lines 8 and 9 is only shifted in the sub-scanning direction 212. Therefore, as described in the first embodiment, the deviation of the reading lines 8 and 9 can be corrected by processing the image stored in the memory 5 by the processing device 6 regardless of the unevenness of the document surface.

  In FIG. 17, the internal structure is shown so that the configuration of the optical element can be easily understood. However, in practice, it is preferable to provide the light shielding members 123 and 124 and the light shielding slit 122 as shown in FIG. . In this example, the optical system has an F value = 20 to increase the depth of field and a small amount of light taken into the imaging optical system. In other words, most of the light rays scattered from the document 7 by the illumination light are light rays that do not form an image, and it is necessary to effectively shield them.

  For that purpose, in the light shielding slit 122 having the opening region 122a, the opening regions 122a are also preferably arranged in a staggered manner. Further, the light path after the aperture 101 is shielded from the outside by the light shielding members 123 and 124, so that the resistance to stray light is further enhanced. Furthermore, by installing the light-shielding slit 120 in the optical path portion after the third folding mirror 113, the resistance to stray light can be further increased. In order to facilitate understanding of the configuration of the light shielding slit 120, FIG. 21 shows the light shielding slit 120 by inverting the top and bottom of FIG. 20. In the light shielding slit 120, an opening 120 a for passing light is provided corresponding to the imaging element portions 41, 42, 43,.

  In addition, the aperture 101 is a transmissive type, and as shown in FIG. 17, a light shielding wall 121 is provided between adjacent cells in the same row, and the optical system after the aperture 101 is in an independent closed chamber state. , Has produced a great effect as a stray light countermeasure. That is, stray light exists only through a small opening of the aperture 101. By making the inner wall surfaces of the light shielding wall 121 and the light shielding members 123 and 124 black, a great stray light countermeasure effect can be obtained.

  As one method for realizing such an imaging optical system, a method in which one member also serves as an optical member in the same row is conceivable. For example, if a lens array in which concave mirrors corresponding to the first concave mirror 100A and the second concave mirror 102A are arranged at an interval of 18 mm is used, and an aperture array corresponding to the aperture 101 and having aperture holes at intervals of 18 mm is used. good. The first folding mirror 111, the second folding mirror 112, and the third folding mirror 113 may be formed by depositing a reflective member such as aluminum on a single thin plate. Since the first folding mirror 111 and the second folding mirror 112 are disposed adjacent to each other, for example, a reflecting member may be deposited on both slopes of a roof shape having a triangular cross section.

  As described above, if the image blur correction process based on the distance measurement process from the focal position to the document surface described in the first embodiment is performed for the practical optical design as described above, the above-described optical system is used. It is possible to further increase the depth of field of 3 mm from the top 3. For example, if Δz ≦ 3 mm as a result of distance measurement, blur correction processing is not performed, and blur correction is performed only when the distance Δz exceeds 3 mm. By adopting such a configuration, the applicant has confirmed that an image having a sufficient resolution can be obtained by the blur correction process up to a distance Δz = 6 mm.

  As described above, the mirror 111 to 113 that bends the optical path is provided, and the lens in the cell is configured by, for example, a concave mirror of the reflective condensing elements 100A and 102A, so that the image reading is compact and has a large depth of field. A device can be obtained.

  Here, as a development of the second embodiment, the case where each cell 11, 12,... Is a telecentric optical system on the side of the original document 7 has been described, but the folding mirrors 111 to 113 and the concave mirrors 100A and 102A are provided. Of course, the configuration used can be easily developed in the image reading apparatus 201 of the first embodiment.

Embodiment 5 FIG.
Next, an example of the image reading device 205 in the fifth embodiment of the present invention will be described with reference to FIGS.
FIG. 22 shows the internal structure of the reading optical system portion of the image reading device 205. However, in FIG. 22, illustration of the illumination light source 2, the top plate 3, the image sensor substrate 4, the memory 5, the processing device 6, and the like is omitted in order to avoid the complexity of the illustration. FIG. 23 is a perspective view illustrating the optical path in the sub-scanning direction 212 with the main scanning direction 211 perpendicular to the paper surface. FIG. 24 shows an optical system unit to which a light shielding member is attached as shown in FIG.

  The image reading device 205 according to the fifth embodiment also has the same configuration as that of the image reading device 204 according to the fourth embodiment, except for differences described below. Therefore, detailed description here is omitted. Further, since the image reading device 205 has the same configuration as that of the image reading device 204, the image reading device 205 can basically exhibit the above-described effects that the image reading device 204 has.

  The difference between the image reading device 204 of the fourth embodiment and the image reading device 205 of the fifth embodiment is that, in the fourth embodiment, the aperture 101 has a transmissive opening, whereas in the present embodiment, A reflection mirror is formed corresponding to the opening. The periphery of the reflection area in the reflection mirror is made of a black member that blocks light. Thus, although the said reflective mirror in this Embodiment 5 is a thing which fulfill | performs the function similar to the aperture 101 demonstrated in Embodiment 1-4, a form differs. Therefore, in the following description, the example corresponding to the aperture 101 and corresponding to the example of fulfilling the aperture function is read as the reflecting mirror 101A.

  The optical path will be described with reference to FIG. In FIG. 23, the optical path indicated by the dotted line represents the cell 11, 13,... Belonging to the first column 215, and the optical path indicated by the solid line represents the cell 12, 14,. The optical path (dotted line) relating to the first row 215 is reflected on the right side of the drawing by the first bending mirror 111, collimated by the first concave mirror 100A, and reaches the reflecting mirror 101A installed on the left side of the drawing. Here, the light reaching the outside of the reflection region having a diameter of 1 mm in the reflection mirror 101A is absorbed by the black member. The light beam reflected by the reflection region of the reflection mirror 101A is collected by the second concave mirror 102A installed on the right side of the figure, and then picked up by the third folding mirror 113 installed on the left side of the figure. , ... imaged on top. The entire optical system is provided with a light shielding slit 122 and a light shielding member 125 as shown in FIG. 24 in order to block stray light from the outside.

Since the obtained image is the same as that in the fourth embodiment, description of the effect is omitted. Here, only differences from the fourth embodiment will be described.
In the fourth embodiment, since the portion corresponding to the opening of the aperture 101 is configured by the reflection mirror in the fifth embodiment, the size of the optical system can be reduced in the sub-scanning direction 212. . Specifically, the distance between the optical elements in the sub-scanning direction 212 in the fourth embodiment is about 60 mm, whereas the distance between the optical elements in the sub-scanning direction 212 in the fifth embodiment is It is about 20 mm and is reduced to about one third.

  Furthermore, since the fifth embodiment also has a one-to-one transfer magnification, as shown in FIG. 23, the first concave mirror 100A and the second concave mirror 102A included in the optical system in the first column 215, and the second column 216 are included. The reflection mirror 101 </ b> A included in the optical system can be installed on the same plane along the main scanning direction 211. Similarly, the first concave mirror 100A, the second concave mirror 102A, and the reflection mirror 101A included in the optical system in the second row 216 can be installed on the same plane.

  According to such a configuration, an effect that the assembly of the optical system can be easily performed with high accuracy can be obtained by forming a two-dimensional lens array by resin molding including the first concave mirror 100A and the second concave mirror 102A. It is done. Furthermore, by using the aperture 101, a mirror-finished reflective member is attached to the opening, and a portion other than the opening is made of a black member. There is also an effect that a reflection mirror array can be produced. In this case, the aperture 101 used in the first to fourth embodiments can be used.

  In addition, it is also possible to take the structure which combined each Embodiment 1-5 mentioned above suitably.

1 is a perspective view showing a configuration of an image reading apparatus according to Embodiment 1 of the present invention. It is the figure which showed the main optical path of the image reading apparatus shown in FIG. It is a figure which shows the structural part and main optical path of an imaging optical system in the image reading apparatus shown in FIG. It is a figure for demonstrating the crossing position of the main optical path of the image reading apparatus shown in FIG. FIG. 2 is a diagram for explaining reading of a document by the image reading apparatus shown in FIG. 1. 3 is a flowchart showing image combining processing executed by the image reading apparatus shown in FIG. 1. It is a figure for demonstrating the crossing position of the main optical path of the image reading apparatus shown in FIG. It is a figure for demonstrating the image combination process performed with the image reading apparatus shown in FIG. It is a figure for demonstrating the joint position detection process performed with the image reading apparatus shown in FIG. It is a figure for demonstrating the smoothing process at the time of the image combination performed with the image reading apparatus shown in FIG. It is a figure for demonstrating the crossing position of the main optical path of the image reading apparatus shown in FIG. It is a figure for demonstrating the image combination process of the image reading apparatus shown in FIG. It is a figure for demonstrating the blurring correction process of the image reading apparatus shown in FIG. It is a figure which shows the structure and main optical path of the image reading apparatus which concern on Embodiment 2 of this invention. It is a figure which shows the structural part and main optical path of an imaging optical system in the image reading apparatus shown in FIG. It is a figure which shows the structural part and main optical path of an image formation optical system in the image reader which concerns on Embodiment 3 of this invention. It is a perspective view which shows the internal structure of the imaging optical system in the image reader which concerns on Embodiment 4 of this invention. FIG. 18 is a perspective view showing an optical system for one cell in the image reading apparatus shown in FIG. 17. FIG. 18 is a perspective view in the sub-scanning direction in the image reading apparatus shown in FIG. 17. It is a perspective view which shows the light-shielding member of the image reading apparatus shown in FIG. It is a perspective view which shows the back surface of the image reading apparatus shown in FIG. It is a perspective view which shows the internal structure of the optical system in the image reading apparatus which concerns on Embodiment 5 of this invention. It is a figure which shows the optical path in the image reading apparatus shown in FIG. It is a perspective view which shows the light-shielding member in the image reading apparatus shown in FIG. It is a figure for demonstrating the image combination process of the image reading apparatus shown in FIG.

Explanation of symbols

1 imaging optical system, 2 illumination light source, 3 top plate, 4 substrate, 5 memory,
6 processor, 7 manuscript,
11, 12, 13, 14,... Cell, 31, 32, 33, 34,.
41, 42, 43, 44,... Image sensor unit, 61 Image correction unit,
100 first lens, 101 aperture, 102 second lens,
211 main scanning direction, 212 sub-scanning direction, 215 first row, 216 second row,
201-205 Image reading apparatus.

Claims (5)

A top plate on which the document is placed;
A light source for irradiating the imaged part of the document with light;
An imaging optical system that collects the scattered light of the light reflected by the imaging section and forms an image as an image, and has a plurality of cells arranged in the main scanning direction, each of which is an independent optical system. An imaging optical system in which the cells are arranged in two rows, the first row and the second row in the scanning direction, and the cells are arranged in a staggered pattern in the main scanning direction so as to complement the field of view of each cell; ,
A plurality of image sensor sections that are arranged corresponding to each of the cells and image each image formed in the cell;
A memory for storing image information obtained from the imaging element unit;
An image reading apparatus comprising: a processing device that creates a document image by restoring and combining the image information stored in the memory for each image corresponding to the cell;
The chief rays from the imaged part toward the cells are parallel between the cells arranged along the main scanning direction in the same row of the first row and the second row, and are arranged in the first row. Between each cell and each cell arranged in the second row is inclined toward the gap between the first row and the second row,
The processing apparatus includes an image correction unit, and the image correction unit is arranged in the first column and the second column in the sub-scanning direction, and each piece of image information obtained from the imaging element unit corresponding to each cell. A distance from the focal position to the imaged part in the focal direction from the deviation in the sub-scanning direction, and the original image is created by correcting the image information based on the distance.
An image reading apparatus.   The image reading apparatus according to claim 1, wherein all the cells provided in the first row and the second row are optical systems telecentric on the document side.   The image reading apparatus according to claim 1, further comprising a bending member configured to bend the optical path of the reflected light from the image pickup unit to the image pickup device unit.   The image reading apparatus according to claim 1, wherein the cell includes a plurality of optical elements and a diaphragm, and at least one of the optical elements is a reflection / condensing mirror.   The image reading apparatus according to claim 4, wherein the diaphragm is formed by a reflection mirror.