JP2005057381A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus capable of improving an effectual resolution while suppressing deterioration in imaging sensitivity. <P>SOLUTION: This image reading apparatus is provided with a photoelectric converting section for applying photoelectric conversion to the light of an original to be image-read into a predetermined reading direction to generate an image signal of the reading direction, and a sub-scanner for relatively moving the original and the photoelectric converter in a sub-scanning direction to perform sub-scanning. In this image reading apparatus, the reading direction of the photoelectric converter is set at an inclined angle θ(θ≠90°) obliquely to the sub-scanning direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus that scans and reads a document (such as a film) and generates image data.
[0002]
[Prior art]
12 and 13 are diagrams for explaining a scanning method of a conventional image reading apparatus.
Hereinafter, these two conventional examples A and B will be described.
[0003]
[Conventional example A]
In the scanning method of Conventional Example A shown in FIG. 12, a line sensor 81 is installed perpendicular to the sub-scanning direction of the document. The line sensor 81 is configured by arranging light receiving elements in a line.
The line sensor 81 reads the document line by line every time the document is sub-scanned by the sampling interval Ds. By combining the line unit images, a read image of the document is completed.
[0004]
[Conventional example B]
In the scanning method of Conventional Example B shown in FIG. 13, a line sensor 82 is installed perpendicular to the sub-scanning direction of the document. The line sensor 82 is provided with two light receiving element rows 82a and 82b. These light receiving element arrays 82a and 82b are arranged with pixel positions shifted from each other by a half phase.
The line sensor 82 reads out the original with two light receiving element arrays, and outputs image data shifted in pixels. By combining the pixel-shifted image data, a read image of the document is completed.
[0005]
[Problems to be solved by the invention]
In an image reading apparatus, in order to read an original more precisely, higher resolution is required.
In the conventional example A, the resolution can be increased by increasing the number of pixels of the line sensor 81. However, when the number of pixels of the line sensor 81 is increased, the aperture per light receiving element is reduced, so that the imaging sensitivity is lowered. As a result, there is a problem that the S / N of the image data output from the line sensor 81 is lowered. Further, in order to compensate for this decrease in imaging sensitivity, the exposure time of the line sensor 81 has to be set long, and there is a problem that the image reading time of the image reading device becomes long.
[0006]
On the other hand, in Conventional Example B, it is possible to obtain image data for two lines shifted by pixels for one line of the document. By synthesizing the image data for two lines shifted by the pixels, it is possible to realize high resolution. However, in the line sensor 82, since the overlapping ratio of the apertures between the lines is as large as about 50% in the vertical direction, the sharpness of the read image in the vertical direction becomes low. For this reason, it is difficult to read the fine detail components of the document, and there is a problem that the effective resolution of the read image is lowered.
Therefore, an object of the present invention is to provide an image reading apparatus capable of increasing effective resolution while suppressing a decrease in imaging sensitivity.
[0007]
[Means for Solving the Problems]
The present invention will be described below.
[0008]
<Claim 1>
The image reading apparatus according to claim 1, a photoelectric conversion unit that photoelectrically converts light of a document that is an image reading target in a predetermined reading direction, and generates an image signal in the reading direction; a document and a photoelectric conversion unit; And a sub-scanning unit that performs sub-scanning by relatively moving in the sub-scanning direction. In this image reading apparatus, the reading direction of the photoelectric conversion unit is set obliquely at an inclination angle θ (θ ≠ 90 degrees) with respect to the sub-scanning direction.
[0009]
<Claim 2>
According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the sub-scanning unit performs sub-scanning so that the image sampling interval Ds in the sub-scanning direction by the photoelectric conversion unit is equal to the following equation: To do.
Image sampling interval Ds in the sub-scanning direction = (image sampling interval Dm in the reading direction) · cos θ (1)
[0010]
<Claim 3>
According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, the sub-scanning unit performs sub-scanning so that the image sampling interval Ds in the sub-scanning direction by the photoelectric conversion unit is equal to the following formula. .
Image sampling interval Ds in the sub-scanning direction = 2 (image sampling interval Dm in the reading direction) cos θ (2)
[0011]
<Claim 4>
According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the photoelectric conversion unit includes a plurality of light receiving element arrays arranged in the reading direction in the sub-scanning direction. This is a side-by-side configuration.
[0012]
<Claim 5>
According to a fifth aspect of the present invention, in the image reading apparatus according to the fourth aspect, in the photoelectric conversion unit, the light receiving elements are arranged in parallel in the sub-scanning direction.
[0013]
<Claim 6>
A sixth aspect of the present invention is the image reading apparatus according to any one of the first to fifth aspects, further comprising an adjustment mechanism that varies the inclination angle θ of the photoelectric conversion unit.
[0014]
<Claim 7>
According to a seventh aspect of the present invention, in the image reading device according to any one of the first to sixth aspects, an image signal in the reading direction that is sequentially output from the photoelectric conversion unit in accordance with the sub-scanning is obtained. An inclination conversion unit is provided that converts an image signal in the main scanning direction substantially orthogonal to the scanning direction to generate a read image of the document.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below with reference to the drawings.
[0016]
<< First Embodiment >>
The first embodiment is an embodiment corresponding to claims 1, 2, 3, 6, and 7.
FIG. 1 is a diagram illustrating an image reading apparatus 11 according to the present embodiment.
In FIG. 1, a film 12 is loaded in the image reading device 11. An LED light source 13 composed of a plurality of LEDs (such as RGB and infrared light I LEDs) is disposed at the insertion destination of the film 12. The LED light source 13 is driven by an LED drive circuit 13a. The LED drive circuit 13 a is controlled by a light emission control signal from the microprocessor 14.
[0017]
The illumination light that has passed through the film 12 passes through the lens 15 and forms an optical image of the film 12. The light receiving element array of the line sensor 16 is arranged in alignment with the image plane of the optical image. The line sensor 16 photoelectrically converts the optical image in accordance with a control signal from the microprocessor 14 to generate image data.
The line sensor 16 is disposed on a rotation stage 32 that is rotated by a sensor rotation mechanism 31. The microprocessor 14 varies the inclination angle θ (see FIG. 3) of the line sensor 16 by rotating the rotation stage 32 via the sensor rotation mechanism 31.
[0018]
On the other hand, a film position detection sensor 17 is disposed around the film 12. The sensor output from the film position detection sensor 17 is output to the microprocessor 14. The microprocessor 14 gives a control signal to the film driving mechanism 23 in accordance with the sensor output. The film driving mechanism 23 intermittently moves (sub-scans) the film 12 in the longitudinal direction according to this control signal. The film 12 side may be fixed and the optical system side may be moved.
[0019]
In synchronism with such sub-scanning of the film 12, the line sensor 16 outputs image data scanned line-sequentially. The image data is digitized via the A / D converter 25 and then given to the image processing circuit 26. The image processing circuit 26 performs image processing on the image data. The image processing circuit 26 is connected to the buffer memory 27 via the bus 21.
The microprocessor 14 and the interface 28 are also connected to the bus 21. The image reading apparatus 11 is connected to an external computer 29 via the interface 28.
[0020]
[Correspondence with Invention]
The correspondence relationship between the invention and this embodiment will be described below. Note that the correspondence relationship here illustrates one interpretation for reference, and does not limit the present invention.
The photoelectric conversion unit described in the claims corresponds to the line sensor 16.
The sub-scanning unit described in the claims corresponds to the film driving mechanism 23 and the microprocessor 14.
The adjustment mechanism described in the claims corresponds to the sensor rotation mechanism 31.
The inclination conversion unit described in the claims corresponds to the computer 29.
[0021]
[Description of Operation of First Embodiment]
FIG. 2 is a flowchart for explaining the operation of the first embodiment.
Here, an outline of an operation relating to image reading will be first described along the processing steps shown in FIG.
[0022]
Step S1: The microprocessor 14 rotates the rotation stage 32 via the sensor rotation mechanism 31, and adjusts the inclination angle θ of the line sensor 16 to the set value of the user. This inclination angle θ is an inclination angle with respect to the sub-scanning direction of the film 12, as shown in FIG.
[0023]
Step S2: The microprocessor 14 determines the mode selection by the user.
Here, when the full scan mode is selected, the microprocessor 14 shifts the operation to step S3.
On the other hand, if the checkered scan mode is selected, the microprocessor 14 proceeds to step S4.
[0024]
Step S3: In response to the user selection in the full scanning mode, the microprocessor 14 sets the image sampling interval Ds in the sub-scanning direction to a value of the following expression.
Ds = (pixel interval Dm of line sensors) · cos θ (1)
After such setting operation, the microprocessor 14 shifts the operation to step S5.
[0025]
Step S4: In response to the user selection in the checkered scanning mode, the microprocessor 14 sets the image sampling interval Ds in the sub-scanning direction to a value of the following expression.
Ds = 2 · (pixel interval Dm of line sensor) · cos θ (2)
After such setting operation, the microprocessor 14 shifts the operation to step S5.
[0026]
Step S5: The microprocessor 14 controls the film driving mechanism 23 to move the film 12 to the reading start position. As shown in FIG. 5A, this “reading start position” is a position where the light receiving element of the line sensor 16 first overlaps the frame start position of the film 12.
[0027]
Step S6: The microprocessor 14 sequentially turns on the LED light sources 13 in units of colors, and reads the light image of the film 12 line-sequentially via the line sensor 16. At this time, as shown in FIG. 3, the line sensor 16 outputs RGB signals in the direction inclined by the inclination angle θ with respect to the sub-scanning direction (that is, the reading direction) for each line.
[0028]
Step S7: The microprocessor 14 performs A / D conversion on the RGB signals and then transfers them to the computer 29.
[0029]
Step S8: The microprocessor 14 determines whether or not the sub-scanning of the film 12 has been completed.
If the sub-scanning has not ended, the microprocessor 14 proceeds to step S9.
On the other hand, when the sub-scanning is finished, the microprocessor 14 shifts the operation to step S10.
[0030]
Step S9: The microprocessor 14 moves the film 12 in the sub-scanning direction by the image sampling interval Ds set in Step S3 or Step S4. After changing the reading position of the line sensor 16 in this way, the microprocessor 14 returns the operation to step S6.
By repeating the operations in steps S6 to S9 in this manner, the film 12 is two-dimensionally scanned and a scanned image is generated.
FIG. 3 is a diagram illustrating a state of two-dimensional scanning in the full scanning mode. On the other hand, FIG. 8 is a diagram showing a state of two-dimensional scanning in the checkered scanning mode.
[0031]
Step S10: The computer 29 (driver program) excludes unnecessary portions from the scanned image based on the inclination angle θ, the shape standard of the film 12, and the like. This unnecessary portion is a region where a part of the line sensor 16 is deviated from the effective screen of the film 12 due to the inclination of the line sensor 16 or the like. Examples of the unnecessary portion include an image such as a tongue portion (film leader) of the film 12, a portion between frames, a mount portion of a slide, an image portion of an adjacent frame, and a film perforation.
Note that unnecessary portions related to adjacent frames may be effectively used as pre-scan images of adjacent frames or as scanned images of adjacent frames. Such efficient processing can further shorten the image reading time of the film 12.
[0032]
Step S11: The computer 29 (driver program) performs image processing on the scan image of the tilted pixel array in accordance with the value of the tilt angle θ, and converts it into a read image in which pixels are arranged in the main scan direction (hereinafter referred to as this conversion). Is called “inclination transformation”).
[0033]
Step S12: The computer 29 (driver program) determines whether or not the current scanning mode is the checkered scanning mode.
In the checkered scan mode, the computer 29 (driver program) shifts the operation to step S13.
On the other hand, in the full scan mode, the computer 29 (driver program) passes the read image generated in step S11 to application software or the like, and completes the operation.
[0034]
Step S13: In the checkered scan mode, a read image sampled in a checkered pattern is generated. The computer 29 (driver program) interpolates the read image with pixels and aligns the signals of all the pixels. The computer 29 passes the read image after interpolation to application software or the like, and completes the operation.
The image reading of the film 12 is completed by the series of operations described above. Next, the effect in each scanning mode is demonstrated concretely.
[0035]
[Operation effect of full scan mode]
FIG. 4 is a diagram showing sampling positions in the full scan mode. FIG. 5 is a diagram for explaining pixel rearrangement. In FIG. 5, the odd-numbered and even-numbered samplings are shown separately in FIGS. 5A and 5B so that the positional relationship of the pixels becomes clear.
In this full scan mode, the sub-scanning image sampling interval Ds is set so as to satisfy the above equation [1]. By performing sub-scanning at the image sampling interval Ds, the scanning image sampling positions are arranged in a grid as shown in FIG.
At this time, the sampling interval in the sub-scanning direction is equal to Ds (= Dm · cos θ), and the sampling interval in the main scanning direction is equal to Dm · sin θ.
[0036]
In particular, when the tilt angle θ is set to 45 degrees, the vertical and horizontal sampling intervals coincide with each other, so that it is possible to obtain a scanned image of square pixels (pixel vertical and horizontal interval ratio is 1).
[0037]
In this way, grid-like image sampling is performed in the full scan mode. Therefore, in the above-described inclination conversion (step S11), it is only necessary to rearrange the pixels of the scanned image in a grid-like order, and a read image can be easily generated. (Specifically, in the scanned image shown in FIG. 5, the pixels may be rearranged in the order of a11, a12, a13... A21, a22, a23.
[0038]
Further, in such a full scanning mode, by tilting the line sensor 16, the pixel interval (= Dm · sin θ) in the main scanning direction can be shortened, and an increase in the number of pixels in the main scanning direction can be achieved.
[0039]
For example, in the present embodiment, as compared with the conventional example A, it is possible to increase the number of pixels in the main scanning direction as described below.
When the inclination angle θ = 60 degrees, the number of pixels in the main scanning direction is about 1.15 times. When the inclination angle θ = 45 degrees, the number of pixels in the main scanning direction is about 1.41 times. When the inclination angle θ = 30 degrees, The number of pixels in the scanning direction is about 2.00 times.
On the other hand, if the increase in the number of pixels in the main scanning direction is suppressed to some extent, it becomes possible to use the line sensor 16 having a large distance Dm between the light receiving elements. In this case, as shown in an example in FIG. 6, the aperture of each light receiving element can be enlarged as compared with the conventional example A. By expanding the aperture, the imaging sensitivity of the line sensor 16 can be increased.
[0041]
For example, in the present embodiment, the following imaging sensitivity can be improved as compared with the conventional example A.
When the tilt angle θ = 60 degrees, the imaging sensitivity is about 1.3 times. When the tilt angle θ = 45 degrees, the imaging sensitivity is about 2.0 times. When the tilt angle θ = 30 degrees, the imaging sensitivity is about 4.0 times. By improving the imaging sensitivity, it is possible to increase the image S / N of the scanned image.
[0042]
Further, with the expansion of the aperture, the signal charge storage capacity is increased, the signal dynamic range is expanded, and an image signal rich in gradation can be generated.
[0043]
Further, by shortening the exposure time of the line sensor 16 as much as the imaging sensitivity is increased, the image reading time can be shortened.
[0044]
Further, in this full scan mode, the overlapping ratio of apertures between lines can be made smaller than that in the conventional example B as shown in FIG. As a result, it is possible to generate a read image with a higher sharpness than the conventional example B. In particular, in the full scan mode of the present embodiment, the apertures overlap in the vertical and horizontal directions in a balanced manner, so that there is no unnaturalness that the sharpness decreases only in the vertical direction as in the conventional example B, and a natural read image can be obtained. There are advantages.
[0045]
Further, in the full scan mode, the pixel interval (= Dm · sin θ) in the main scanning direction can be flexibly changed by adjusting the inclination angle θ of the line sensor 16. As a result, an image reading apparatus capable of adjusting the optical resolution in the main scanning direction can be realized.
[0046]
[Operation effect of checkered scan mode]
FIG. 9 is a diagram showing sampling positions in the checkered scan mode.
In this checkered scan mode, the sub-scanning image sampling interval Ds is set so as to satisfy the above-described equation [2]. In this image sampling interval Ds, the sampling position of the scanned image has a checkered pattern as shown in FIG.
At this time, the minimum resolvable interval in the sub-scanning direction is equal to Dm · cos θ, and the minimum resolvable interval in the main scanning direction is equal to Dm · sin θ.
[0047]
In particular, when the tilt angle θ is set to 45 degrees, the minimum horizontal and vertical resolvable intervals coincide with each other, so that it is possible to obtain a natural scanned image in which the resolution performance is balanced vertically and horizontally.
[0048]
Thus, in the checkered scan mode, sampling is performed in a checkered pattern. Therefore, in the above-described inclination conversion (step S11), each pixel of the scanned image may be assigned and rearranged in a checkered order, and a checkered read image can be easily generated. By performing the interpolation processing in step S13 on the checkered array read image, a lattice array read image is generated.
[0049]
Further, in such a checkered scanning mode, by tilting the line sensor 16, it is possible to reduce the pixel interval (= 2Dm · sin θ) in the main scanning direction and increase the number of pixels in the main scanning direction.
[0050]
On the other hand, if the increase in the number of pixels in the main scanning direction is suppressed to some extent, it becomes possible to use the line sensor 16 having a wider interval Dm between the light receiving elements. Also in this case, as shown in FIG. 6, the aperture of each light receiving element can be enlarged as compared with the conventional example A. By expanding the aperture, it is possible to obtain effects such as improved imaging sensitivity, improved image S / N, expanded signal dynamic range, and shortened image reading time.
[0051]
Furthermore, in the checkered scanning mode, the resolvable pixel interval (= Dm · sin θ) in the main scanning direction can be changed by adjusting the inclination angle θ of the line sensor 16. As a result, an image reading apparatus capable of adjusting the resolution limit in the main scanning direction can be realized.
Next, another embodiment will be described.
[0052]
<< Second Embodiment >>
The second embodiment is an embodiment corresponding to claims 1 to 7.
A structural feature of the second embodiment is that a line sensor 41 shown in FIG. 10A is arranged in place of the line sensor 16 shown in FIG. The line sensor 41 is configured by arranging two or more light receiving element arrays 41a and 41b in the sub-scanning direction.
[0053]
Thus, by arranging the light receiving element arrays 41a and 41b in the sub-scanning direction, it is possible to output a plurality of lines of image signals at a time. As a result, the number of movements in the sub-scanning direction can be reduced and the image reading time can be shortened.
In the line sensor 41 shown in FIG. 10A, the light receiving elements are arranged in parallel in the sub-scanning direction. Therefore, since the sampling positions of the scanned image are arranged in parallel in the sub-scanning direction, the tilt conversion of the scanned image is facilitated.
[0054]
Incidentally, if the light receiving elements are not parallel to the sub-scanning direction due to the change in the inclination angle θ, for example, the phases of the light receiving element arrays 41a and 41b may be shifted in the reading direction as shown in FIG. 10B. Further, for example, as shown in FIG. 10C, the interval between the light receiving element arrays 41a and 41b may be adjusted. These adjustments make it possible to align the light receiving elements in the sub-scanning direction. Such adjustment can be realized by a mechanical or optical mechanism.
[0055]
<< Additional items of embodiment >>
By the way, in the above-described embodiment, the image sampling interval Ds in the sub-scanning direction is determined using the equation [1] or [2]. At such an image sampling interval Ds, as shown in FIGS. 4 and 9, the sampling positions of the scanned image are aligned in the main scanning direction. As a result, the gradient conversion can be performed quickly and easily by only pixel rearrangement.
[0056]
However, the present invention is not limited to this. For example, the image sampling interval in the sub-scanning direction may be set to a value different from the expression [1] or [2]. FIG. 11 is a diagram illustrating a state in which different image sampling intervals are set. Also in this case, it can be seen that the sampling positions are evenly distributed over the entire image, and a good scan image can be obtained. However, since each pixel of such a scanned image does not correspond to each pixel of the final read image on a one-to-one basis, the slope conversion cannot be easily performed by pixel rearrangement. In such a case, the gradient conversion may be performed using a linear interpolation method, a bilinear method, a bicubic method, a nearest neighbor method, a weighted average based on area specific gravity or distance, and other image interpolation methods.
[0057]
In the above-described embodiment, the line sensor 16 is spatially arranged obliquely. However, the present invention is not limited to this. For example, the reading direction of the line sensor 16 may be inclined with respect to the sub-scanning direction by forming an optical image inclined by the optical system. Furthermore, the tilt angle θ in the reading direction may be varied by varying the tilt angle of the optical image using an optical system.
[0058]
In the above-described embodiment, the case where the slope conversion is performed on the computer 29 side has been described. However, the present invention is not limited to this. For example, tilt conversion may be performed inside the image reading apparatus 11 (such as the microprocessor 14 or the image processing circuit 26).
[0059]
In the above-described embodiment, the case where the user sets the tilt angle θ has been described. However, the present invention is not limited to this. For example, the tilt angle θ may be fixed. Further, for example, the variable range of the tilt angle θ may be limited so that the tilt angle θ is excessively small and the effective screen of the film 12 does not protrude from the line sensor 16. In addition, a control unit that variably controls the tilt angle θ may be provided so that the effective screen of the film 12 does not protrude from the line sensor 16 according to the film size (size of the original in the main scanning direction).
[0060]
Furthermore, in the above-described embodiment, the case where the inclination angle θ is set to other than 90 degrees has been described. However, the present invention does not exclude the case where the inclination angle θ is set to 90 degrees. For example, when the inclination angle θ is set to 90 degrees in the above-described embodiment, a reading operation similar to that of the conventional apparatus may be performed.
[0061]
As a preferred application of the present invention, the inclination angle θ of the photoelectric conversion unit can be held at a constant value during scanning with respect to the document to be read or the sub-scanning direction. As a more preferable application, the image sampling interval in the sub-scanning direction can be held at a constant value during scanning. If these conditions are satisfied, it is possible to reliably and accurately achieve the above-described effects such as an increase in pixels and an improvement in imaging sensitivity at a fine pixel scale level. From such a viewpoint, the present invention is not limited to the film scanner of the embodiment, and may be applied to a flat bed scanner or the like.
[0062]
【The invention's effect】
In the image reading apparatus of the present invention, the reading direction of the photoelectric conversion unit is set obliquely at an inclination angle θ (θ ≠ 90 degrees) with respect to the sub-scanning direction. With such an oblique setting, the photoelectric conversion unit becomes longer in the reading direction than in the conventional example A. For this reason, the aperture of the light receiving element can be made larger than that of the conventional example A, and a decrease in imaging sensitivity due to an increase in the number of pixels can be suppressed.
Furthermore, in the image reading apparatus of the present invention, the aperture overlap rate can be made smaller than that of the conventional example B, and it becomes easy to increase the effective resolution.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image reading apparatus 11;
FIG. 2 is a flowchart illustrating the operation of the first embodiment.
FIG. 3 is a diagram illustrating a state of two-dimensional scanning in the full scanning mode.
FIG. 4 is a diagram illustrating sampling positions in the full scan mode.
FIG. 5 is a diagram illustrating pixel rearrangement.
FIG. 6 is a comparative view of apertures.
FIG. 7 is a comparison diagram of aperture overlap rates.
FIG. 8 is a diagram illustrating a state of two-dimensional scanning in a checkered scanning mode.
FIG. 9 is a diagram showing sampling positions in a checkered scan mode.
FIG. 10 is a diagram for explaining the operation of the second embodiment.
FIG. 11 is a diagram illustrating an example of a sampling position of a scanned image.
12 is a diagram for explaining a scanning method of Conventional Example A. FIG.
13 is a diagram for explaining a scanning method of Conventional Example B. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Image reader 12 Film 13 LED light source 13a LED drive circuit 14 Microprocessor 15 Lens 16 Line sensor 17 Film position detection sensor 21 Bus 23 Film drive mechanism 26 Image processing circuit 27 Buffer memory 28 Interface 29 Computer 31 Sensor rotation mechanism 32 times Moving stage 33 Sensor rotation mechanism 41 Line sensor

Claims (7)

A photoelectric conversion unit that photoelectrically converts light of a document that is an image reading target in a predetermined reading direction, and generates an image signal in the reading direction;
An image reading apparatus including a sub-scanning unit that performs sub-scanning by relatively moving the document and the photoelectric conversion unit in a sub-scanning direction,
The image reading apparatus, wherein the reading direction of the photoelectric conversion unit is set obliquely at an inclination angle θ (θ ≠ 90 degrees) with respect to the sub-scanning direction. The image reading apparatus according to claim 1,
The sub-scanning unit performs the sub-scanning image sampling interval Ds = (in the reading direction) so that the sub-scanning image sampling interval Ds by the photoelectric conversion unit is equal to the following equation. Image sampling interval Dm) · cos θ (1)
An image reading apparatus. The image reading apparatus according to claim 1,
The sub-scanning unit performs the sub-scanning so that the image sampling interval Ds in the sub-scanning direction by the photoelectric conversion unit is equal to the following formula: image sampling interval Ds in the sub-scanning direction Ds = 2 · (the reading direction Image sampling interval Dm) · cos θ (2)
An image reading apparatus. The image reading apparatus according to any one of claims 1 to 3,
2. The image reading apparatus according to claim 1, wherein the photoelectric conversion unit has a configuration in which a plurality of light receiving element arrays arranged in the reading direction are arranged in the sub-scanning direction. The image reading apparatus according to claim 4.
The image reading apparatus, wherein the photoelectric conversion unit includes light receiving elements arranged in parallel in the sub-scanning direction. The image reading apparatus according to any one of claims 1 to 5,
An image reading apparatus comprising an adjustment mechanism that varies the tilt angle θ of the photoelectric conversion unit. The image reading apparatus according to any one of claims 1 to 6,
The image signal in the reading direction sequentially output from the photoelectric conversion unit in association with the sub-scanning is converted into an image signal in the main scanning direction substantially orthogonal to the sub-scanning direction to generate a read image of the document. An image reading apparatus comprising an inclination conversion unit.

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