JP2019186739A - Image reading apparatus - Google Patents

Abstract

To provide an image reading apparatus that can achieve high image quality.SOLUTION: An image reading apparatus according to the present invention comprises: illumination means that illuminates an object; light-receiving means that receives reflected light from the object; image formation means that guides the reflected light to the light-receiving means; a first position changing means that changes a position of the light-receiving means; and a control unit that controls the first position changing means. In the light-receiving means, at least three light-receiving element rows, in each of which light-receiving elements are arranged in a first direction to be formed, are provided in a second direction such that two first color light-receiving elements, two second color light-receiving elements, and two third color light-receiving elements are respectively not adjacent to each other in each of the first direction and the second direction being orthogonal to each other in a first surface being orthogonal to an optical axis of the image formation means, and the control unit controls the first position changing means on the basis of luminance signals which are output from each of a plurality of light-receiving elements arranged at a predetermined position in the first direction of the light-receiving means.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image reading apparatus, and more particularly to an apparatus using a line sensor.

Conventionally, as color image reading means of a document reading apparatus such as a copying machine or MFP (multifunction printer), light receiving elements coated with R (red), G (green), and B (blue) color filters are arranged in a line. An arranged line sensor is used.
In Patent Document 1, a plurality of light receiving elements are arranged in a first direction in a second direction in which a light receiving element array in which R → G → B → R... Is periodically and repeatedly arranged is perpendicular to the first direction. An image reading apparatus capable of detecting dust adhering to the apparatus and correcting the read color image to improve the image quality by using a plurality of line sensors arranged in the apparatus is disclosed.

JP 2017-204805 A

However, in Patent Document 1, since pixel data obtained by each light receiving element in a plurality of light receiving element rows is rearranged, spatial information regarding the second direction is lost in the obtained image data. .
Since Patent Document 1 does not examine this lost spatial information, position adjustment is performed even if a plurality of light receiving element arrays are displaced from the nominal position in the second direction due to assembly errors, environmental changes, and the like. Cannot be performed, leading to degradation of image quality.
Accordingly, the present invention provides an image reading apparatus capable of achieving further higher image quality by appropriately performing optical adjustment on line sensors arranged so that light receiving elements of different colors are not adjacent to each other. For the purpose.

  An image reading apparatus according to the present invention includes an illuminating unit that illuminates an object, a light receiving unit that receives reflected light reflected from the object and that is light emitted from the illuminating unit, and a structure that guides the reflected light to the light receiving unit. An image unit; a first position changing unit that changes the position of the light receiving unit; and a control unit that controls the first position changing unit. In the light receiving unit, the light receiving elements of the first color, The color light receiving elements and the third color light receiving elements are not adjacent to each other in each of the first and second directions perpendicular to each other in the first plane perpendicular to the optical axis of the imaging means. A light receiving element array formed by arranging a plurality of light receiving elements of a first color, a plurality of light receiving elements of a second color, and a plurality of light receiving elements of a third color in the first direction is a second direction. At least three, and the controller is configured to determine the predetermined direction of the light receiving means in the first direction. Based on the luminance signal outputted from each of the plurality of light receiving elements arranged in a position, and controlling the first position changing means.

  According to the present invention, there is provided an image reading apparatus capable of achieving further image quality improvement by appropriately performing optical adjustment on a line sensor arranged so that light receiving elements of different colors are not adjacent to each other. can do.

1 is a schematic cross-sectional view of an image reading apparatus according to a first embodiment. FIG. 3 is a schematic cross-sectional view in the vicinity of a document reading unit of the image reading apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating an array structure of light receiving elements included in a line sensor provided in the image reading apparatus according to the first embodiment. FIG. 3 is a configuration diagram of a reading control system provided in the image reading apparatus according to the first embodiment. FIG. 2 is a schematic cross-sectional view of a document reading unit provided with an optical adjustment device in the image reading apparatus according to the first embodiment. FIG. 3 is a diagram schematically illustrating a chart used for adjusting a document reading unit provided in the image reading apparatus according to the first embodiment. The figure which showed the example of the output luminance signal obtained when the adjustment reference chart was read in the image reading apparatus which concerns on 1st embodiment. FIG. 4 is an enlarged view of an example of an output luminance signal obtained when an adjustment reference chart is read by the image reading apparatus according to the first embodiment.

  Hereinafter, an image reading apparatus according to the present embodiment will be described in detail with reference to the accompanying drawings. It should be noted that the drawings shown below may be drawn at a scale different from the actual scale so that the present embodiment can be easily understood.

FIG. 1 is a schematic cross-sectional view of an image reading apparatus 100 according to the first embodiment.
The image reading apparatus 100 includes a document tray 101 on which a document 102 (object) is placed, and document reading units 103 and 106.
The document reading units 103 and 106 read images of the document 102 conveyed by various document conveyance motors.
An original background plate is provided on the original platen glass 112 so as to come to the back of the original 102. When the reading of the image of the original 102 in the original reading units 103 and 106 is completed, the image reading apparatus 100 discharges the original 102 to the paper discharge tray 104.

When only one side of the document is read, only the document reading unit 103 is used to read the image of the document 102. When both sides of the document are read, both the document reading units 103 and 106 are used to read the image of the document 102. Read.
Since the document reading units 103 and 106 have the same configuration, the document reading unit 103 will be described below.

  FIG. 2 is a schematic cross-sectional view in the vicinity of the document reading unit 103 of the image reading apparatus 100 according to the present embodiment.

The document reading unit 103 includes a light source unit 201 (illuminating unit), an imaging lens 202 (imaging unit), a line sensor 203 (light receiving unit), and mirrors 204, 205, 206, and 207.
The light source unit 201 is provided at a predetermined site in the document reading unit 103 so as to irradiate light toward the document 102 passing through the document reading position.
The mirrors 204, 205, 206, and 207 reflect and deflect reflected light from the document 102 to the imaging lens 202.
The line sensor 203 photoelectrically converts the reflected light from the original 102 collected (guided) by the imaging lens 202 using a plurality of light receiving elements, and outputs a signal corresponding to the intensity (light quantity) of the reflected light. To do.
The imaging lens 202 and the mirrors 204, 205, 206, and 207 constitute an optical system of the document reading unit 103, and the positions where the document 102 and the line sensor 203 are arranged are conjugated with each other.

The line sensor 203 is, for example, a CMOS linear image sensor. A CCD linear image sensor may be used.
The line sensor 203 is formed by arranging a plurality of light receiving elements that receive reflected light from the document 102. Here, one light receiving element corresponds to one pixel, and the width of one light receiving element corresponds to one pixel width. That is, for example, the three-pixel width indicates a width corresponding to three light receiving elements.
In the following, regarding the pixels in the case of describing the image of the document 102, an image read by one light receiving element of the line sensor 203 will be described as an image of one pixel (one pixel width).

The light receiving elements forming the line sensor 203 include a first color light receiving element that detects red light (first color: R), and a second color that detects green light (second color: G). And a third color light receiving element for detecting blue light (third color: B).
The R, G, and B light receiving elements are periodically arranged in the first direction for each pixel width. As a result, a light receiving element array in which R → G → B is repeated in the first direction is formed.
The line sensor 203 is configured by arranging a plurality of such light receiving element arrays in a second direction perpendicular to the first direction in the light receiving surface.

In this embodiment, an R pixel is a pixel corresponding to the first color light receiving element that receives red light, a G pixel is a pixel corresponding to the second color light receiving element that receives green light, and a blue light is used. A pixel corresponding to the light receiving element of the third color that receives light is referred to as a B pixel.
The light receiving element array formed in the first direction is called a line. That is, one line is formed by one light receiving element array, and the line sensor 203 has a plurality of light receiving element arrays that form one line at a predetermined interval in a second direction perpendicular to the first direction. Has been.

  FIG. 3 is a schematic diagram for explaining the arrangement structure of the light receiving elements included in the line sensor 203 provided in the image reading apparatus 100 of the present embodiment.

As shown in FIG. 3, in the line sensor 203, a line in which 7500 light receiving elements are arranged in the main scanning direction which is the first direction is a second line perpendicular to the optical axis direction and the first direction. Are arranged in three rows in the sub-scanning direction. That is, in the line sensor 203, 7500 × 3 (22500 pixels) light receiving elements are provided.
Note that the image reading apparatus 100 according to the present embodiment is described as reading an image with a resolution of 600 dpi (dots per inch) in the main scanning direction, but this resolution is only an example.

  As described above, the main scanning direction is a direction in which a plurality of light receiving elements are arranged in a line, and this corresponds to the width direction of the document to be read (the direction perpendicular to the transport direction in the drawing). The sub-scanning direction is a direction orthogonal to the main scanning direction on the light receiving surface of the line sensor 203, and this corresponds to the conveyance direction of the document to be read.

As shown in FIG. 3, the three lines L1, L2, and L3 are arranged apart from each other by a predetermined pixel width (predetermined interval) in the sub-scanning direction.
In the image reading apparatus 100 according to the present embodiment, the predetermined interval between the lines of the line sensor 203 is one pixel width. Therefore, the line L1 and the line L2 are separated by two pixels, and the line L1 and the line L3 are separated by four pixels.

  As shown in FIG. 3, in the image reading apparatus 100 of the present embodiment, the colors at the respective pixel positions in the main scanning direction are different between adjacent lines among the three rows of lines of the line sensor 203. It is configured. In other words, in the image reading apparatus 100 according to the present embodiment, the colors of the start end pixels of the cycle of R → G → B are different between the three lines of the line sensor 203.

Specifically, each line has regularity of R → G → B → R → G → B →... In the main scanning direction, and the color of the start end pixel (pixel 1) of the line L1 is R. (Red), the color of the start end pixel of the line L2 is B (blue), and the color of the start end pixel of the line L3 is G (green).
That is, in the line L2, the light receiving elements are arranged so that the regularity is shifted in the main scanning direction by one pixel with respect to the line L1, and in the line L3, the regularity is equivalent to two pixels with respect to the line L1. The light receiving elements are arranged so as to be shifted in the main scanning direction only.

Thus, in the line sensor 203, the R, G, and B light receiving elements are arranged in a so-called staggered pattern.
That is, in the line sensor 203, the light receiving elements at the respective pixel positions in the main scanning direction of the lines L1, L2, and L3 are arranged so that the colors are different between adjacent lines.
In other words, in the line sensor 203, the first surface in which the light receiving elements of the first color, the light receiving elements of the second color, and the light receiving elements of the third color are perpendicular to the optical axis of the imaging lens 202. A plurality of first-color light-receiving elements, a plurality of second-color light-receiving elements, and a plurality of third-color light-receiving elements so as not to be adjacent to each other in each of the main scanning direction and the sub-scanning direction perpendicular to each other Are arranged in the main scanning direction, and three light receiving element arrays are provided in the sub scanning direction.
With the above configuration, the line sensor 203 simultaneously outputs the detection results of the image signals on the three lines separated in the sub-scanning direction as described above when reading the document 102.

  FIG. 4 is a configuration diagram of a reading control system (control unit) 400 provided in the image reading apparatus 100 according to the present embodiment.

The image reading apparatus 100 includes a computer having a CPU 401 and a nonvolatile memory 409 as main components.
The CPU 401 reads out and executes the computer program stored in the nonvolatile memory 409, thereby causing the image reading apparatus 100 having the components illustrated in FIG. 1 to execute a characteristic image reading operation.
Further, the CPU 401 controls operations of the light source unit 201, the line sensor 203, the document transport motor 105, and the like based on an instruction from the user input to the operation unit 408, and performs control for reading an image on the document 102.

  A specific image reading operation in the reading control system 400 provided in the image reading apparatus 100 according to the present embodiment is performed as follows.

The CPU 401 controls the light source unit 201 and the line sensor 203 to read the image of the original 102 illuminated by the light source unit 201 as a set of a plurality of pixels having different colors adjacent to each other in the main scanning direction and the sub scanning direction.
Each color light receiving element of the line sensor 203 outputs a signal corresponding to the intensity (light quantity) of the light reflected and input from the document 102. This signal corresponds to color density information in each pixel of the image of the original 102 and is an analog signal, and therefore is converted into image data which is a digital signal by the A / D conversion circuit 402.
In the image reading apparatus 100 according to the present embodiment, the A / D conversion circuit 402 has 8-bit resolution for convenience, but is not limited thereto.

  Next, the CPU 401 stores the read image data of each color in the line memory 404 in association with relative positional information between the image data and other image data for each line. Here, the relative position information is an arrangement position of each light receiving element of the line sensor 203, and corresponds to the address when corresponding to the address of the line memory 404.

The data sorting circuit 403 is a circuit as an example of a sorting unit, and rearranges the image data stored in the line memory 404 so that pixels of the same color are adjacent to each other, that is, a pixel row of the same color. At this time, the red pixel row obtained by the rearrangement is called “R line”, the green pixel row is called “G line”, and the blue pixel row is called “B line”.
The image data rearranged into the R line, G line, and B line by the data sort circuit 403 is input to the shading correction circuit 405.
The shading correction circuit 405 is a circuit that performs shading correction of image data in order to correct the influence of non-uniformity in the amount of light emitted from the light source unit 201, pixel sensitivity of the line sensor 203, and the like. The image data corrected by the shading correction circuit 405 is output from the shading correction circuit 405 as a luminance signal.

  Next, a method for adjusting the document reading unit 103 provided in the image reading apparatus 100 according to the present embodiment will be described.

FIG. 5 is a schematic cross-sectional view of the document reading unit 103 provided with the optical adjustment device in the image reading apparatus 100 according to the present embodiment.
FIG. 6 schematically shows an adjustment reference chart 300 used for adjustment of the document reading unit 103 provided in the image reading apparatus 100 according to the present embodiment.

  In the image reading apparatus 100 according to the present embodiment, the optical adjustment device adjusts the resolving power characteristic and the geometric characteristic in the document reading unit 103. Specifically, the line sensor position adjusting unit 320 and the imaging lens position adjustment are adjusted. And means 321.

In the image reading apparatus 100 according to the present embodiment, when the document reading unit 103 is assembled, first, the light source unit 201, the imaging lens 202, the line sensor 203, the mirrors 204, 205, 206, and 207 are necessary in the housing 209. Assemble the optical components.
Then, the positions of the imaging lens 202 and the line sensor 203 are adjusted using an imaging lens position adjusting unit 321 (second position changing unit) and a line sensor position adjusting unit 320 (first position changing unit), respectively. .
Here, the adjustment items include magnification adjustment, center alignment in the main scanning direction, center alignment in the sub-scanning direction, rotation direction alignment around the optical axis (scan line inclination adjustment), and focus position alignment.

In the image reading apparatus 100 according to the present embodiment, for these adjustments, the adjustment reference chart 300 is arranged at a position where the original surface of the original 102 is arranged, and the image of the adjustment reference chart 300 is passed through the imaging lens 202. And projected onto the line sensor 203.
Then, various determination amounts are calculated from the luminance signal from the line sensor 203 that has read the image, and the positions of the imaging lens 202 and the line sensor 203 are adjusted so that they become desired values. Adjustment is performed by the line sensor position adjusting means 320. Specifically, the optical axis direction of the imaging lens 202 and the line sensor 203, the main scanning direction and the sub scanning direction perpendicular to the optical axis, the rotational direction around the optical axis, and the rotational axis parallel to the sub scanning direction. Adjust the position for the direction of rotation.

  Next, a chart pattern of the adjustment reference chart 300 used for adjustment of the document reading unit 103 provided in the image reading apparatus 100 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 6, the adjustment reference chart 300 includes two types of chart patterns, one is a resolution evaluation pattern portion 301 and the other is a geometric characteristic evaluation pattern. Part 302.
The chart patterns 301 and 302 are arranged at a plurality of angles of view so as to be symmetric with respect to the main scanning center pattern 303 which is a line perpendicular to the main scanning direction arranged at the center of the adjustment reference chart 300 in the main scanning direction. Has been.

  The resolving power evaluation pattern unit 301 includes a sub-scanning resolving power evaluation unit 301a composed of a lattice pattern in which white lines and black lines substantially parallel to the sub-scanning direction are arranged in parallel to each other at equal intervals, and white and black lines substantially parallel to the main scanning direction. The main scanning resolving power evaluation unit 301b includes a lattice pattern in which lines are arranged in parallel with each other at equal intervals. Therefore, the lattice pattern of the sub-scanning resolution evaluation unit 301a and the lattice pattern of the main-scanning resolution evaluation unit 301b are orthogonal to each other.

The widths of the white line and the black line constituting the respective lattice patterns of the sub-scanning resolution evaluation unit 301a and the main-scanning resolution evaluation unit 301b are both 0.085 mm. That is, the image reading apparatus 100 according to the present embodiment is configured to perform CTF (Contrast Transfer Function) evaluation at a frequency of 5.9 L / mm.
The CTF value is calculated by the following equation (1) using the maximum value MAX and the minimum value MIN of the luminance signal from the sub-scanning resolution evaluation unit 301a and the main-scanning resolution evaluation unit 301b.

The geometric characteristic evaluation pattern portion 302 includes a line 302b perpendicular to the main scanning direction and a line 302a forming an angle θ with respect to the line 302b.
As will be described below, the magnification deviation in the main scanning direction (main scanning magnification deviation) from the interval between the two lines 302b, the one-fold difference from the difference between the main scanning center pattern 303 and each of the two lines 302b, and the line 302a The reading position in the sub-scanning direction can be detected from the distance between the line 302b and the line 302b.
In the image reading apparatus 100 according to the present embodiment, the angle θ is set to 45 ° so that it can be easily calculated, but it may not be 45 °.

  Next, a specific calculation method of various determination amounts for adjustment of the document reading unit 103 in the image reading apparatus 100 according to the present embodiment will be described.

  FIG. 7 shows an example of an output luminance signal as an image signal obtained when the adjustment reference chart 300 is read by the line sensor 203 in the image reading apparatus 100 according to the present embodiment.

Waveforms 301a and 301b shown in FIG. 7 are output luminance signals obtained when the sub-scanning resolution evaluation unit 301a and the main-scanning resolution evaluation unit 301b are read. The 302a waveform and the 302b waveform are output luminance signals obtained when the geometric characteristic evaluation pattern portion 302a and the geometric characteristic evaluation pattern portion 302b are read, respectively.
The 302a waveform and the 302b waveform are acquired by rearranging the luminance signals obtained by the lines L1, L2, and L3 so as to be the R line, G line, and B line by using the data sort circuit 403. is doing.

For each of the geometric characteristic evaluation pattern portions 302a and 302b, the output luminance signals of the R pixel, the G pixel, and the B pixel at each pixel position in the main scanning direction are added and normalized (averaged). The luminance signal Ave for geometric evaluation is acquired.
This process assumes that one pixel that is long in the sub-scanning direction (that is, five pixels long) is provided at each pixel position in the main scanning direction of the line sensor 203, and the line L2 is substantially the adjustment reference chart 300. It is calculated which position in the upper sub-scanning direction is detected.

  When the output luminance signals obtained by the line L1, the line L2, and the line L3 are rearranged by the data sort circuit 403, phase information in the sub-scanning direction regarding the detection position in the sub-scanning direction on the adjustment reference chart 300 by the line sensor 203 is obtained. It will be missing. In order to compensate for this, this summing process is performed.

FIG. 8 is an enlarged view of an output luminance signal as an image signal obtained when the line sensor 203 reads the geometric characteristic evaluation pattern portion 302 of the adjustment reference chart 300 in the image reading apparatus 100 according to the present embodiment. Yes.
Here, the luminance signal Ave for geometric evaluation shown in FIG. 8 is standardized by adding the output luminance signals of the R pixel, G pixel, and B pixel at each pixel position, and dividing by the total number of pixels (that is, 3). It has become.

When this geometric evaluation luminance signal Ave is used, the same applies even when the scanning line is extremely inclined (for example, the output luminance signal of the vertical line 302b is detected as the output luminance signal of the oblique line 302a). Thus, the correct position information of the vertical line 302b can be detected.
In addition, since the same calculation is possible even with the conventional line sensors including the R line, the G line, and the B line, which are the light receiving element arrays of the same color, the line L1, the line L2, and the line L3 can be easily performed. It is also effective in that comparative verification is possible.

  Next, a method for specifically calculating various determination amounts related to the sub-scanning direction from the geometric evaluation luminance signal Ave will be described.

First, as shown in FIG. 8, the 302b portion corresponding to the vertical line 302b (first line image) and the 302a portion corresponding to the diagonal line 302a (second line image) in the luminance signal Ave for geometric evaluation, respectively. 302bc and 302ac are calculated as the midpoint pixel position (hereinafter, this may be referred to as the midpoint position in the main scanning direction of the waveform) when the 50% slice of the peak value is set as the threshold value for the waveform of Let the interval be L ₁ (pixel).
Further, as shown in FIG. 6, the interval between the vertical line 302b and the oblique line 302a on the adjustment reference axis of the adjustment reference chart 300 is assumed to be l ₁ (mm).

そして、本実施形態に係る画像読取装置１００では、線３０２ａと線３０２ｂとの間の角度θは４５°となっているため、副走査方向の位置ズレ量Δｓ（ｍｍ）はこのΔｌ_１と同じ値となる。
そして、算出されたΔｓが所定の範囲内に入るように、ラインセンサ位置調整手段３２０を用いてラインセンサ２０３を副走査方向に移動させることによって副走査方向の位置調整を行うことができる。 At this time, the imaging magnification of the imaging lens 202 beta, when the pixel size of the line sensor 203 and p (mm), is calculated by the positional deviation amount in the main scanning direction .DELTA.l ₁ (mm) is the following formula (2) be able to.

In the image reading apparatus 100 according to this embodiment, since the angle θ between lines 302a and line 302b has a 45 °, the sub-scanning direction positional shift amount Delta] s (mm) is the same as the .DELTA.l ₁ Value.
Then, the position adjustment in the sub-scanning direction can be performed by moving the line sensor 203 in the sub-scanning direction using the line sensor position adjusting unit 320 so that the calculated Δs falls within a predetermined range.

Further, the amount of inclination of the scanning line is calculated from the difference between Δs detected from the geometric characteristic evaluation pattern portion 302 arranged in the vicinity of both the left and right ends with the main scanning center pattern 303 on the adjustment reference chart 300 interposed therebetween. be able to.
In other words, the distance between the left vertical line 302b (the first line image) and hatched 302a (second line image) and _{l 1} across the main scanning center pattern 303. Then, the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the left vertical line 302b and the reflection from the left oblique line 302a. Let L ₁ (pixel) be the distance from the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive light.

から算出されるΔｓ_１とΔｓ_２との差が走査線傾き量に対応している。すなわち、算出されたΔｓ_１−Δｓ_２が所定の範囲内に入るように、ラインセンサ位置調整手段３２０を用いてラインセンサ２０３を光軸のまわりに回転させることによって光軸のまわりの回転方向の位置調整を行うことができる。 Further, the distance between the main scanning center pattern 303 interposed therebetween in right side which is located opposite the vertical line 302b (third line image) and hatched 302a (Fourth line image) and l _2. Then, the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the right vertical line 302b and the reflection from the right oblique line 302a. Let L ₂ (pixel) be the distance from the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive light. At this time,

The difference between Δs ₁ and Δs ₂ calculated from the above corresponds to the scan line inclination amount. That is, by rotating the line sensor 203 around the optical axis using the line sensor position adjusting unit 320 so that the calculated Δs ₁ −Δs ₂ falls within a predetermined range, the rotational direction around the optical axis is increased. Position adjustment can be performed.

  Next, a method for specifically calculating various determination amounts regarding the main scanning direction from the geometric evaluation luminance signal Ave will be described.

The half-fold difference is the difference between the left and right end portions of the main scanning center pattern 303 arranged at the center in the main scanning direction of the adjustment reference chart 300 and the second surface that includes the optical axis of the imaging lens 202 and is perpendicular to the main scanning direction. It can be calculated from the left-right difference in the distance from the vertical line 302b arranged in the vicinity.
Therefore, using the above-described method, the half-fold difference can be obtained from the difference between Δl regarding the vertical line 303 and the left and right vertical lines 302b.
In other words, the interval between the main scanning center pattern 303 (fifth line image) and the left vertical line 302b (first line image) is set to l _L. Then, the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the main scanning center pattern 303 and the left vertical line 302b. Let L _L (pixel) be the distance from the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light.

から算出されるΔｌ_LとΔｌ_Rとの差が片倍差に対応している。すなわち、算出されたΔｌ_L−Δｌ_Rが所定の範囲内に入るように、ラインセンサ位置調整手段３２０を用いてラインセンサ２０３を副走査方向に平行な回転軸のまわりに回転させることによって片倍差を調整することができる。 Further, the distance between the main scanning center pattern 303 and the right vertical line 302b (third line image) and _{l R.} Then, the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the main scanning center pattern 303, and the right vertical line 302b. _Let L _R (pixel) be the distance from the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light. At this time,

The difference between Δl _L and Δl _R calculated from the above corresponds to the half-fold difference. That is, the line sensor 203 is rotated about the rotation axis parallel to the sub-scanning direction by using the line sensor position adjusting means 320 so that the calculated Δl _L −Δl _R falls within a predetermined range. The difference can be adjusted.

から算出されるΔｌ_３が主走査倍率に対応している。すなわち、算出されたΔｌ_３が所定の範囲内に入るように、ラインセンサ位置調整手段３２０及び結像レンズ位置調整手段３２１をそれぞれ用いて、ラインセンサ２０３及び結像レンズ２０２の光軸方向の位置を調整することによって主走査倍率を調整することができる。 The main scanning magnification can be calculated from the interval between the vertical lines 302b arranged in the vicinity of both left and right ends.
Therefore, the interval between the left vertical line 302b (first line image) and the right vertical line 302b (third line image) is set to l ₃ . Then, the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the left vertical line 302b, and from the right vertical line 302b. Let L ₃ (pixel) be the distance from the midpoint position in the main scanning direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive the reflected light. At this time,

Is .DELTA.l ₃ calculated from corresponds to the main scanning magnification. That is, the position of the line sensor 203 and the imaging lens 202 in the optical axis direction is used by using the line sensor position adjusting unit 320 and the imaging lens position adjusting unit 321 so that the calculated Δl ₃ falls within a predetermined range. The main scanning magnification can be adjusted by adjusting.

Specifically, when adjusting the main scanning magnification, first, the best imaging position is calculated by a known method using the resolution evaluation pattern unit 301 in advance. Then, the position of the line sensor 203 in the optical axis direction is adjusted by the line sensor position adjusting means 320 so that the line sensor 203 is arranged at that position.
In this state, the main scanning magnification is calculated, and when the calculated main scanning magnification is out of the predetermined range, the imaging lens 202 and the line sensor 203 are respectively connected to the imaging lens position adjusting unit 321 and the line sensor position. The position is adjusted in the optical axis direction using the adjusting means 320. In this way, the main scanning magnification can be adjusted while maintaining the best imaging state.
The main scanning magnification can also be defined using the sum of Δl _L and Δl _R calculated from the above equations (5) and (6).

  In the image reading apparatus 100 according to the present embodiment, the luminance signals output from the respective light receiving elements of the line sensor 203 are added together. However, the present invention is not limited to this, and noise removal and signal are output from the output luminance signals. You may add together the signal obtained by performing the filtering for amplification.

  As mentioned above, although preferable embodiment was described, it is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

100 Image reading apparatus 102 Document (object)
201 Light source unit (illumination means)
202 Imaging lens (imaging means)
203 Line sensor (light receiving means)
320 Line sensor position adjusting means (first position changing means)

Claims (10)

Illumination means for illuminating an object;
A light receiving means for receiving reflected light reflected by the object, which is light illuminated from the illumination means;
Imaging means for guiding the reflected light to the light receiving means;
First position changing means for changing the position of the light receiving means;
A control unit for controlling the first position changing means;
With
In the light receiving means, the light receiving elements of the first color, the light receiving elements of the second color, and the light receiving elements of the third color are mutually in a first plane perpendicular to the optical axis of the imaging means. A plurality of light receiving elements of the first color, a plurality of light receiving elements of the second color, and a plurality of light receiving elements of the third color so as not to be adjacent to each other in the vertical first and second directions. Are arranged in the first direction, and at least three light receiving element arrays are provided in the second direction,
The control unit controls the first position changing unit based on a luminance signal output from each of a plurality of light receiving elements arranged at predetermined positions in the first direction of the light receiving unit. A characteristic image reading apparatus.   The controller is configured based on a sum value obtained by summing luminance signals output from a plurality of light receiving elements arranged at predetermined positions in the first direction of the light receiving unit. The image reading apparatus according to claim 1, wherein the position changing unit is controlled.   The image reading apparatus according to claim 1, wherein the control unit controls the first position changing unit to change a position of the light receiving unit in the second direction. The first line image parallel to the second direction in the object arranged at a position conjugate with the light receiving means and the first line image is inclined by 45 ° in the first plane. The distance between the second line image and the second line image in the first direction is l ₁ , and the luminance signal output from each of the plurality of light receiving elements that receive the reflected light from the first line image is obtained. The first waveform of the waveform obtained by adding the luminance signal output from each of the plurality of light receiving elements that receive the reflected light from the second line image and the midpoint position in the first direction of the waveform. When the distance from the midpoint position in the direction is L ₁ (pixel), the imaging magnification of the imaging means is β, and the length of the light receiving element in the first direction is p,

The control unit controls the first position changing unit so as to change the position of the light receiving unit in the second direction so that Δs ₁ calculated from the value falls within a predetermined range. The image reading apparatus according to any one of claims 1 to 3.   5. The control unit according to claim 1, wherein the control unit controls the first position changing unit to change a position of the light receiving unit in a rotational direction around the optical axis. The image reading apparatus described. The first line image parallel to the second direction in the object arranged at a position conjugate with the light receiving means and the first line image is inclined by 45 ° in the first plane. The distance between the second line image and the second line image in the first direction is l ₁ , and the luminance signal output from each of the plurality of light receiving elements that receive the reflected light from the first line image is obtained. The first waveform of the waveform obtained by adding the luminance signal output from each of the plurality of light receiving elements that receive the reflected light from the second line image and the midpoint position in the first direction of the waveform. The distance from the midpoint position in the direction is L ₁ (pixels), and is opposite to the first and second line images with respect to the second surface that includes the optical axis and is perpendicular to the first direction. A third line image parallel to the second direction of the object, Reflection of the serial first plane a distance in the first direction between the fourth line images are inclined 45 ° with respect to said third line images l _2, from the third line image A plurality of light receiving portions that receive reflected light from the midpoint position in the first direction and the fourth line image of the waveform obtained by adding up the luminance signals output from each of the plurality of light receiving elements that receive light. The distance from the midpoint position in the first direction of the waveform obtained by adding the luminance signals output from the respective elements is L ₂ (pixels), the imaging magnification of the imaging means is β, When the length of the light receiving element in the first direction is p,

The first position changing unit is configured to change the rotational position of the light receiving unit around the optical axis so that Δs ₁ −Δs ₂ calculated from the value falls within a predetermined range. The image reading apparatus according to claim 1, wherein the image reading apparatus is controlled.   The said control part controls the said 1st position change means so that the position of the rotation direction around the said 2nd direction of the said light-receiving means may be changed. The image reading apparatus according to item. A first line image parallel to the second direction of the object arranged at a position conjugate with the light receiving means, and a second surface including the optical axis and perpendicular to the first direction. On the other hand, the third line image disposed on the opposite side of the first line image, and the first line image and the third line image in the first direction are disposed between the first line image and the third line image. in the fifth line images are, the distance in the first direction between the first and fifth line image l _L, each of the plurality of light receiving elements for receiving reflected light from said first line image Luminance signals output from each of a plurality of light receiving elements that receive the midpoint position in the first direction and the reflected light from the fifth line image of the waveform obtained by summing the luminance signals output from The distance from the midpoint position in the first direction of the waveform obtained by the summation is expressed as L _L ( Pixel), a distance in the first direction between the third and fifth line images as l _R , and a luminance signal output from each of a plurality of light receiving elements that receive reflected light from the third line image Of the waveform obtained by adding together the luminance signal output from each of the plurality of light receiving elements that receive the reflected light from the fifth line image and the midpoint position in the first direction. The distance between the waveform and the midpoint position in the first direction is L _R (pixel), the imaging magnification of the imaging means is β, and the length of the light receiving element in the first direction is p. When

So that Δl _L −Δl _R calculated from the value falls within a predetermined range, the control unit changes the position of the light receiving means in the rotational direction around the second direction. The image reading apparatus according to claim 1, wherein the changing unit is controlled. Second position changing means for changing the position of the imaging means;
The control unit controls the first and second position changing units so as to change positions of the light receiving unit and the imaging unit in a direction parallel to the optical axis. The image reading apparatus according to claim 8. Second position changing means for changing the position of the imaging means;
A first line image parallel to the second direction of the object arranged at a position conjugate with the light receiving means, and a second surface including the optical axis and perpendicular to the first direction. On the other hand, in the third line image arranged on the opposite side of the first line image, the distance in the first direction between the first and third line images is set to l ₃ , The midpoint position in the first direction and the reflection from the third line image of the waveform obtained by summing the luminance signals output from each of the plurality of light receiving elements that receive the reflected light from the one line image The distance from the midpoint position in the first direction of the waveform obtained by adding the luminance signals output from each of the plurality of light receiving elements that receive light is L ₃ (pixel), When the imaging magnification is β and the length of the light receiving element in the first direction is p,

The first and second control units change the positions of the light receiving means and the imaging means in the direction parallel to the optical axis so that Δl ₃ calculated from the values falls within a predetermined range. The image reading apparatus according to claim 1, wherein the position changing unit is controlled.

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