JPH0591253A - Image reader - Google Patents

Abstract

(57) [Summary] [Object] To provide a colorized image reading device capable of reading high-density information. A light reflected by scanning the surface of the original 2 is condensed by an imaging lens 3 and is incident on a photoelectric conversion element 5, whereby an electric signal corresponding to the reflectance of the original 2 is used as an image signal. In an image reading apparatus that obtains image information by detecting, a first sensor pixel array 5a having a spectral distribution characteristic that is substantially equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution, A photoelectric conversion element 5 including a second sensor pixel row 5b in which read pixels having two types of spectral distribution characteristics different from the distribution are alternately arranged is provided, and the first sensor pixel row 5a and the second sensor pixel row are provided. The position relative to 5b is arranged in the direction of the reflected light from the original 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image reading,
In particular, the present invention relates to an image reading device capable of reading image information at high density.

[0002]

2. Description of the Related Art Conventionally, a photoelectric conversion element such as a CCD sensor has been used to read an original image input by a copying machine, a facsimile, an image filing device or the like. These photoelectric conversion elements have a one-line configuration and are composed of minute cells capable of reading 1 mm with a resolution of several lines to several tens of lines. A conventional image reading device is, for example, Japanese Patent Laid-Open No. 62-23.
There is one disclosed in Japanese Patent No. 5872, etc.,
As a general reading method, the sensor (photoelectric conversion element) itself electrically scans in the line direction (main scanning direction).
Then, the entire sensor is moved in a direction (sub-scanning direction) perpendicular to this. In these devices, colorization has progressed in recent years, and as one method of color-separating and capturing image information, a color sensor having a color filter on a chip is used. An example of such a sensor is "CCD of Toshiba Semiconductor Business Headquarters".
Image sensor "1989, pp. T from 298 to 307
It is described as CD140C.

[0003]

Generally, the image information obtained by colorizing the monochrome image information is far smaller than three times as large as the monochrome image information. One of the reasons is that the color-separated components are highly correlated, that is,
This is because when one component, for example, the R component is large, the other components, the B and G components also become large, and when the R component is small, the B and G components also tend to be small. In addition, as a property of visual characteristics, more detailed information can be recognized for "change in brightness", but rough information can be recognized for "change in hue". The "color information" may not be required as densely as the "brightness information". As described above, for colorization, the total number of pixels of the sensor is three times as large as that in monochrome (three lines of pixel rows), which significantly increases the cost itself.

[0004]

According to a first aspect of the present invention, light reflected by scanning the surface of a document is condensed by an imaging lens and is incident on a photoelectric conversion element, whereby the reflection of the document is performed. In an image reading apparatus that obtains image information by detecting an electric signal according to the ratio as an image signal, it has a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution. A photoelectric conversion element is provided that includes a first sensor pixel row and a second sensor pixel row in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately, and the photoelectric conversion element is provided. The relative arrangement position with respect to the second sensor pixel row is arranged so as to be different in the direction of reflected light from the original.

According to the second aspect of the present invention, the light reflected by scanning the surface of the original is condensed by the imaging lens and is incident on the photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is obtained. In an image reading apparatus that obtains image information by detecting the image signal as an image signal, a first sensor pixel array having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution. A photoelectric conversion element having a second sensor pixel row in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately, and the first sensor pixel row and the second sensor pixel row are provided.
The sensor pixel row and the sensor pixel row are arranged so that their relative positions are different in the direction of the reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row and the second sensor pixel row. ..

According to the third aspect of the present invention, the light reflected by scanning the surface of the original is condensed by the imaging lens and is incident on the photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is obtained. In an image reading apparatus that obtains image information by detecting the image signal as an image signal, a first sensor pixel array having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution. A photoelectric conversion element having a second sensor pixel row in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately, and the first sensor pixel row and the second sensor pixel row are provided.
The sensor pixel row and the sensor pixel row are arranged at different relative positions in the direction of reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the high frequency components included in the image reading output of the first sensor pixel column are the high frequencies of the R signal, the G signal and the B signal. Arithmetic means is provided to perform arithmetic operation so as to have it as a frequency component.

According to the invention of claim 5, claims 1, 2,
In the invention described in 3 or 4, the shape of each read pixel of the second sensor pixel row is formed to be inclined with respect to the main scanning direction.

According to the invention described in claim 6, claims 1, 2,
In the invention described in 3 or 4, the shape of each read pixel of the first sensor pixel row and the second sensor pixel row is formed to be inclined with respect to the main scanning direction.

[0010]

According to the first aspect of the present invention, the second sensor pixel in which two kinds of read pixels having different spectral distribution characteristics are alternately read by the first sensor pixel column for reading a change in luminance with high visual sensitivity The change in hue is read by the row, and by arranging the two sensor pixel rows so that the arrangement is different, defocusing the generation of new noise (folding distortion) due to the sampling pitch of the hue original being halved Since it is suppressed by doing so, it is possible to perform high-density and high-quality color image reading at a relatively low cost by using two sensor pixel rows.

According to the invention of claim 2, claim 1
In addition to the functions described above, an optical low-pass filter is provided in front of the first sensor pixel row for reading the luminance and the second sensor pixel row for reading the hue, so that the quality is higher, the density is higher, and the cost is relatively low. It is possible to read various color images.

According to the invention of claim 3, claim 1
In addition to the above-mentioned function, an optical low-pass filter is arranged in front of the first sensor pixel row for reading the brightness.
Similar to the described invention, it is possible to perform color image reading with high quality and high density at a relatively low cost.

According to the fourth aspect of the present invention, since the arithmetic means is provided, the color image read output is set to the high-density R signal,
It becomes possible to output as a G signal and a B signal.

According to the fifth aspect of the present invention, the shape of each read pixel of the second sensor pixel row is tilted with respect to the main scanning direction, so that the sampling openings are prevented from being scattered, and the aliasing distortion is caused. Therefore, it is possible to perform color image reading with higher quality and higher density at a relatively low cost.

According to the sixth aspect of the invention, in addition to the read pixels of the second sensor pixel row for reading the change in hue, the read pixels of the first sensor pixel row for reading the change in luminance are also in the main scanning direction. By tilting it, it is possible to soften the sampling aperture and to suppress the aliasing distortion even further, which makes it possible to read color images at a higher quality, higher density, and at a relatively lower cost. It becomes possible to do it.

[0016]

EXAMPLE A first example of the present invention will be described. Here, the light reflected by scanning the surface of the original is condensed by the imaging lens and is incident on the photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is detected as an image signal. In an image reading device for obtaining image information,
The first sensor pixel row having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution, and the spectral distribution different from the first sensor pixel array 2
Second array of alternating read pixels with different spectral distribution characteristics
A photoelectric conversion element provided with a sensor pixel column,
The relative arrangement positions of the sensor pixel row and the second sensor pixel row are different in the direction X of the reflected light from the document. The roles of the first sensor pixel row and the second sensor pixel row and the reason why these two sensors are arranged differently in the direction of reflected light will be described below.

First, the first sensor pixel row is for reading the brightness (luminance) of an image. For this purpose, the spectral transmittance characteristic of the color filter is made to match the spectral luminous efficiency characteristic of the naked eye, for example. As a result, it is possible to obtain monochrome image information without deterioration in density. The second sensor pixel row is for reading the hue information, and two kinds of color filters having different spectral transmittance characteristics, for example, R component reading color filters and B component reading color filters are alternately arranged. To be placed in. As a result, the density is 1 compared to the monochrome information.
It is possible to obtain two hue components of / 2.
However, the color image information composed of these three components is sufficiently comparable in density to monochrome density. The reason is that, as described above, the visual characteristics have a higher resolving power with respect to the change in luminance.

The information read by the pixel row for reading the hue information equivalently has the spatial aperture ratio of the read pixels deteriorated to 1/2, so that a side effect of sampling the read pixels, that is, aliasing. Distortion easily occurs.
This also occurs in lower frequency components of the original image because the sampling frequency for each component is halved. In order to avoid this, the distance from the imaging lens of the second sensor pixel row for hue reading is set to the first for luminance reading.
The position is set to be defocused with respect to the sensor pixel column. As a result, the high frequency components of the image are removed by defocusing before sampling, and it is possible to effectively suppress the occurrence of aliasing distortion.

Therefore, as described above, two sensor pixel rows are prepared, one of the first sensor pixel rows is used to read image brightness information at a high density, and the other second sensor pixel row is read.
It is used for reading the hue information of the image by the sensor pixel row, and is arranged so as to be alternately covered with the color filters having two spectral equivalent ratio characteristics, and the distance of the pixel row for reading the hue information from the imaging lens is By setting the position where the brightness information is defocused with respect to the pixel row from which the brightness information is read, it is possible to suppress the occurrence of aliasing distortion due to sampling.
High-density, high-quality color image information can be read.

Next, a concrete example of this embodiment will be described with reference to FIGS.
It will be explained based on. First, as shown in FIG.
A document 2 is arranged on the light source 1, and light emitted from the light source 1 is applied to the document 2, and an imaging lens 3 is provided on the optical path of the light reflected by the document 2. A sensor substrate 4 is arranged on the optical path of the light passing through the imaging lens 3, and a first sensor pixel row 5a (pixel row for reading luminance information) and a second sensor pixel row are provided on the sensor substrate 4. 5
b (pixel array for reading hue information) is provided. In this case, the first sensor pixel row 5a
And the relative position of the second sensor pixel row 5b is different in the direction Y of the reflected light from the original 2.
FIG. 1B shows a positional relationship between the first sensor pixel row 5a and the second sensor pixel row 5b. Note that FIG.
In (a), the X direction in the longitudinal direction of the pixel row is the main scanning direction, and the direction perpendicular to the paper surface is the sub scanning direction.

In such a structure, the light emitted from the light source 1 scans the surface of the original 2, and the light reflected by the light is condensed by the imaging lens 3 and the first sensor pixel array 5 is formed.
a and an image is formed on the surface of the second sensor pixel row 5b. At this time, the distance from the image forming lens 3 to the first sensor pixel row 5a for reading the luminance information is set so as to be in focus, so that the distance from the image forming lens 3 of the second sensor pixel row 5b for reading the hue information is set. The distance is in a defocused state slightly deviated from the distance in the focused state. Therefore, the high frequency components of the hue included in the original 2 are smoothed (that is, removed in advance), and the original image is input to the second sensor pixel row 5b.

The pixel structure of the first sensor pixel row 5a and the second sensor pixel row 5b is as shown in FIG. A pixel structure 6 as a reading pixel in FIG. 2A shows an example of the structure of the first sensor pixel row 5a, and Y represents a pixel for reading luminance information. A pixel structure 7 as a read pixel in FIG. 2B shows a structure example of the second sensor pixel row 5b, R is a pixel for reading a red component, B is a pixel for reading a blue component, and these are alternately arranged. It is located in. The spectral transmittance characteristics of these pixels R, B and Y are as shown in FIG.

As shown by the pixel structures 6 and 7, the sampling of the hue information R and B is half the sampling pitch of the luminance information Y. Therefore, the aliasing component due to the sampling of the read pixels, which is caused by the high frequency component of the original 2, is generated in the lower region in the R and B components. The input of high frequency components above a certain level is eliminated, and aliasing distortion is suppressed.

As described above, by using the two pixel rows of the sensor, that is, the first sensor pixel row 5a and the second sensor pixel row 5b, it is possible to obtain a color information substantially equal to the color information read by the three pixel rows. It is possible to read the information of the document 2 with high density and without introducing new noise.

The first sensor pixel row 5a, the second sensor pixel row 5b, and the sensor substrate 4 are, as shown in FIG. 1, the second sensor for reading the hue with respect to the first sensor pixel row 5a for reading the luminance. Although the pixel row 5b is set to be away from the imaging lens 3, conversely, the second sensor pixel row 5b for reading the hue may be set to be closer. In this case, if the first sensor pixel row 5a for reading the luminance is set to be in focus, the second sensor pixel row 5b for reading the hue is in the defocused state.

Next, a second embodiment of the present invention will be described with reference to FIGS. Here, in addition to the constituent requirements of the first embodiment described above, an optical low-pass filter 8 is arranged in front of the first sensor pixel row 5a and the second sensor pixel row 5b. FIG. 5 shows the spatial frequency characteristic of the optical low pass filter 8. In this case, f
sy indicates the sampling spatial frequency of the luminance information Y, fs
r and fsb represent sampling spatial frequencies of the hue information R and B, respectively. As a result, the aliasing component of sampling that may occur when the brightness information is read by the optical low-pass filter 8 can be suppressed by previously removing the component near fsy. It is possible to read high-density color original information without further increasing noise (folding distortion) as compared with the embodiment (see FIG. 1). Also in the case of the present embodiment, the first and second sensor pixel rows 5a and 5b, the sensor substrate 4 are also provided.
The arrangement method may be set so that the second sensor pixel row 5b is closer to the imaging lens 3 side.

Next, a third embodiment of the present invention will be described with reference to FIGS. 6 and 7. Here, the first sensor pixel row 5
The optical low-pass filter 9 is provided only on the front surface of a. In the above-described second embodiment (see FIG. 4), the optical low-pass filter 8 is arranged on the entire surface of both sensor pixel rows, but the same effect can be obtained even if the optical low-pass filter 8 is arranged on only one side as in this embodiment. You can Optical low-pass filter 9
The spatial frequency characteristic of is as shown in FIG. In this case, no filter is arranged on the front surface of the second sensor pixel row 5b for reading the hue information, but there is almost no problem because there is no frequency input above fsr and fsb due to defocusing. Also in the case of the present embodiment, the arrangement method of the first and second sensor pixel rows 5a and 5b and the sensor substrate 4 is set so that the second sensor pixel row 5b is closer to the imaging lens 3 side. However, the arrangement is as shown in FIG.

Next, a fourth embodiment of the present invention will be described with reference to FIG. Here, the above-described first embodiment (FIG.
(See reference), the relative arrangement positions of the first sensor pixel row 5a and the second sensor pixel row 5b are changed. Specifically, as shown in FIG. 8, the first sensor pixel row 5a is arranged at a position farther from the focus point of the imaging lens 3, so that the second sensor pixel row 5b becomes farther from the focus point. It is arranged as follows. By arranging the sensor pixel array farther from the focus point in this way, it is possible to limit the upper limit of the input frequency of the hue information and suppress the occurrence of aliasing distortion due to sampling.

Next, a fifth embodiment of the present invention will be described with reference to FIG. Here, the above-described fourth embodiment (see FIG. 8) is used.
(See) is the reverse configuration. That is,
The first sensor pixel row 5a is arranged so as to be closer to the focus point of the imaging lens 3, and accordingly, the second sensor pixel row 5b is further arranged to be closer to the focus point. is there. Even when the sensor pixel array is arranged closer to the focus point as described above, it is possible to obtain the same effect as in the case of the fourth embodiment described above.

Next, a modification of the pixel structure of the first sensor pixel row 5a and the second sensor pixel row 5b will be described. The pixel structure is not limited to the square shape as shown in FIGS. 2A and 2B described above, and may be the pixel structure as shown in FIGS. That is, first, the pixel structures 10 and 11 of FIGS. 10A and 10B correspond to the pixel structures 6 and 7 of FIGS. 2A and 2B, respectively. In this case,
The shape of the pixel structure 11 of 0 (b) is a trapezoid that is inclined with respect to the main scanning direction X from the square described above. As described above, by obliquely forming the shape of the pixel row for reading the hue information, it is possible to reduce the sampling aperture of each component in the main scanning direction X from being scattered and to reduce the aliasing distortion. .. In addition, FIG.
The pixel structures 12 and 13 of (a) and (b) are shown in FIG.
It shows a modified example of the pixel structures 10 and 11 of (b), and in this case, the pixel structure 12 for reading the luminance information also has a trapezoidal shape, and thereby the same effect as in the case of FIG. 10 can be obtained. it can. By forming the pixel structure in a trapezoidal shape in this manner, even if the pixel structure is square, the substantial aperture is often not 100%, and in such a case, it is significant to use a trapezoidal shape.

Next, an example of the signal processing circuit used in the present invention will be described with reference to FIGS. 12
In the CCD line sensor 14 (corresponding to the photoelectric conversion element 5 of FIG. 1 described above), sample hold circuits 15 and 16 (S / H circuit), A / D conversion circuit 17,
18 are sequentially connected, and a signal is sent to each of them from a clock generator 19a. The A
Shading correction circuits 19 and 20 are connected to the subsequent stages of the / D conversion circuits 17 and 18, and correction memories 21 and 22 are provided in the shading correction circuits 19 and 20, respectively. In the subsequent stage of the shading correction circuit 19, a FIFO memory 23, Yl / Yh
The separation circuit 24 and the G "arithmetic circuit 25 are sequentially connected, and further connected to the output terminal 25a of the G" signal. Further, a demultiplexer 26 and two interpolation circuits 27 and 28 are connected to the subsequent stage of the shading correction circuit 20, an R ″ arithmetic circuit 29 is connected to the interpolation circuit 27, and a B ″ is connected to the interpolation circuit 28. The arithmetic circuit 30 is connected. The R "arithmetic circuit 29 outputs the R" signal to the output terminal 2
9a, and the B "arithmetic circuit 30 is connected to the output terminal 30a of the B" signal. The G "arithmetic circuit 25
And the R ″ arithmetic circuit 29 and the B ″ arithmetic circuit 30
It constitutes a calculation means. In the signal processing circuit as described above, the high frequency components included in the image reading outputs of the first sensor pixel rows 5a and 5b are R ″ signal, G ″ signal,
The calculation is performed so as to have it as a high frequency component of the B "signal, and its function will be described below.

In such a configuration, the CCD line sensor 14 has two pixel columns, and photoelectric conversion charges are transferred by the clock generator 19a to generate an output for each line. Among them, the output of the pixel column for reading the hue information is output. To the sample hold circuit 15, and the output of the pixel column for reading the luminance information is guided to the sample hold circuit 16. Transfer clock components are removed by these sample and hold circuits 15 and 16, respective outputs are led to A / D conversion circuits 17 and 18, converted into digital signals, and led to shading correction circuits 19 and 20. The shading correction circuits 19 and 20 have a function of correcting variations in brightness due to the illumination system and the imaging system, variations in sensitivity of the CCD line sensor 14, and the like. It can be obtained by calculating each called pixel from 21 and 22. The output of the shading correction circuit 19 is led to the FIFO memory 23, where it is delayed by the number of lines in the sub-scanning direction of the two pixel columns in order to match the data timing with the reading position of the hue information. The output of the FIFO memory 23 is as shown in FIG. The output of the shading correction circuit 20 is a sequential signal in which the R signal and the B signal alternately appear, as shown in FIG. This sequential signal can be guided to the demultiplexer 26 and divided into an R signal and a B signal, and these respective signals are as shown in FIGS. 13 (c) and (d).
The Y signal shown in FIG. 13B is separated by the Yl / Yh separation circuit 24 into a low frequency component Yl signal and a high frequency component Yh signal of the Y signal.
Therefore, inside the Yl / Yh separation circuit 24,

[0033]

[Equation 1]

And the sequence of the two low-pass components:

[0035]

[Equation 2]

Create and. These are shown in FIG.
It corresponds to (g) and (h).

Then, these average values Yl = (Y '+
Y) / 2 is output as the low frequency component of the Y signal (see FIG. 13).
(I)), Yh = Y-Yl is output as the high frequency component of the Y signal (FIG. 13 (j)), and Yl + Yh = Y.
The Yl signal is led to the G "arithmetic circuit 25, and the Yh signal is led to the R" arithmetic circuit 29 and the B "arithmetic circuit 30, respectively.

The R signal output from the demultiplexer 26 is guided to the interpolating circuit 27, and the B signal is guided to the interpolating circuit 28. The average value of adjacent pixel data is calculated and the original data string is used as the inter-pixel data. Interpolate, ie

[0039]

[Equation 3]

The value of is the interpolation data. The data strings to which the interpolation data is added are shown in FIGS. 13 (e) and 13 (f), respectively. Of these outputs, the R signal is converted into the G "arithmetic circuit 25,
The R signal is led to the R ”arithmetic circuit 29, and the B signal is transmitted to the G” arithmetic circuit 25,
The B ″ calculation circuit 30 is led.

In the G "arithmetic circuit 25, G" = Yh + (Y
l-rR-bB) / g is calculated. In this case, r + g
+ B = 1, and when the spectral transmittance characteristic is as shown in FIG. 3, for example, r = 0.3, g = 0.6, and b = 0.1. Further, the R ″ calculation circuit 29 performs the calculation of R ″ = Yh + R, and the B ″ calculation circuit 30 performs the calculation of B ″ = Yh + B. The output of the G "arithmetic circuit 25 (Fig. 13 (k)) is output to the G" output terminal and the output of the R "arithmetic circuit (Fig. 13K).
(L)) is led to the output terminal of R ″ and the output of the B ″ arithmetic circuit 30 (FIG. 13 (m)) is led to the output terminal of B ″, whereby three components of the color image signal can be obtained. Become.

Next, the signal processing as described above will be described with reference to the frequency band of each signal as shown in FIG. FIF
The output Y of the O memory 23 has a band as shown in FIG. In addition, R of the output of the demultiplexer 26
The signal is as shown in FIG. 14B, and the B signal is as shown in FIG.
As shown in (c), the band is half that of the Y signal. This is due to the original read pixel density. The output Yl of the Yl / Yh separation circuit 24 is shown in FIG.
(D) and Yh are as shown in FIG. 14 (e). The reason is that Yl is R, G, B as shown in FIG.
This is because each component is a linear combination, and G ″ is as shown in FIG. Further, R ″ is as shown in FIG. 11 (h), and B ″ is as shown in FIG.
It becomes like (i). As described above, the final color image signals G ″, R ″, and B ″ have the components of each color as their low-frequency components, and the high-frequency components have the components of brightness (luminance) with high visual sensitivity. Signal, which results in a high-density color image signal.

[0043]

According to the first aspect of the invention, the light reflected by scanning the surface of the original is condensed by the image forming lens and is incident on the photoelectric conversion element, whereby the reflectance of the original is adjusted. In an image reading apparatus that obtains image information by detecting an electric signal as an image signal, a first sensor pixel having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual spectrum has a spectral distribution. A photoelectric conversion element including a column and a second sensor pixel column in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately is provided, and the first sensor pixel column and the second sensor pixel column are provided.
Since the relative arrangement position with respect to the sensor pixel row is made different in the direction of the reflected light from the original, the first sensor pixel row reads a change in luminance with high visual sensitivity and has different spectral distribution characteristics. The change in hue is read by the second sensor pixel row in which two types of read pixels are alternately arranged, and the two sensor pixel rows are arranged so that the sampling pitch for the original of the hue is halved. By defocusing and suppressing the generation of new noise (folding distortion) due to the above, it is possible to perform high-density and high-quality color image reading using two sensor pixel rows at a relatively low cost. Is.

According to a second aspect of the present invention, the light reflected by scanning the surface of the original is condensed by an imaging lens and made incident on a photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is obtained. In an image reading apparatus that obtains image information by detecting the image signal as an image signal, a first sensor pixel array having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution. A photoelectric conversion element having a second sensor pixel row in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately, and the first sensor pixel row and the second sensor pixel row are provided.
The sensor pixel row and the sensor pixel row are arranged so that their relative positions are different in the direction of the reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row and the second sensor pixel row. Therefore, it has higher quality, higher density, and
It is possible to read a color image at a relatively low cost.

According to a third aspect of the present invention, the light reflected by scanning the surface of the original is condensed by the imaging lens and is incident on the photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is obtained. In an image reading apparatus that obtains image information by detecting the image signal as an image signal, a first sensor pixel array having a spectral distribution characteristic that is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic that covers a wavelength region where the visual has a spectral distribution. A photoelectric conversion element having a second sensor pixel row in which read pixels having two types of spectral distribution characteristics different from the spectral distribution are arranged alternately, and the first sensor pixel row and the second sensor pixel row are provided.
3. The sensor pixel row is arranged so that the relative arrangement position is different in the direction of reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row. Similar to the invention, it is possible to read a color image with high quality and high density and at a relatively low cost.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the high frequency components included in the image reading output of the first sensor pixel column are the high frequencies of the R signal, the G signal and the B signal. Since the arithmetic means for performing the arithmetic operation so as to have it as the frequency component is provided, the color image read output can be outputted as the high density R signal, G signal and B signal.

The invention according to claim 5 is the invention as claimed in claims 1, 2, and 3.
Alternatively, in the invention described in item 4, since the shape of each read pixel of the second sensor pixel row is formed to be inclined with respect to the main scanning direction, it is possible to prevent the sampling openings from being scattered, and further to prevent aliasing distortion. Since the color image can be suppressed, the color image can be read with higher quality and higher density and at a relatively low cost.

The invention according to claim 6 is the invention as defined in claims 1, 2, and 3.
Alternatively, in the invention described in 4, the first sensor pixel column and the second sensor pixel column
Since the shape of each reading pixel of the sensor pixel row is formed to be inclined with respect to the main scanning direction, the sampling aperture can be prevented from becoming scattered, and further, the aliasing distortion can be further suppressed. The color image can be read at a relatively low cost with a higher quality and a higher density.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention,
(A) is a front view of the image reading apparatus, and (b) is a side view thereof.

FIG. 2 is a state diagram showing states of read pixels.

FIG. 3 is a characteristic diagram showing a state of R, B, and Y spectral transmittance characteristics.

FIG. 4 shows a second embodiment of the present invention,
(A) is a front view of the image reading apparatus, and (b) is a side view thereof.

FIG. 5 is a characteristic diagram showing a spatial frequency characteristic of an optical low pass filter.

FIG. 6 shows a third embodiment of the present invention,
(A) is a front view of the image reading apparatus, and (b) is a side view thereof.

FIG. 7 is a side view showing a state in which the arrangement state of sensor pixel columns is changed.

FIG. 8 shows a fourth embodiment of the present invention,
(A) is a front view of the image reading apparatus, and (b) is a side view thereof.

FIG. 9 shows a fifth embodiment of the present invention,
(A) is a front view of the image reading apparatus, and (b) is a side view thereof.

FIG. 10 is a state diagram showing a state in which the shape of a reading pixel for reading hue information is formed so as to be inclined with respect to the main scanning direction.

FIG. 11 is a state diagram showing a state in which the shape of a reading pixel for reading hue information and luminance information is formed so as to be inclined with respect to the main scanning direction.

FIG. 12 is a circuit diagram showing a state of a signal processing circuit.

FIG. 13 is a state diagram showing an output state in each circuit of the signal processing circuit.

FIG. 14 is a characteristic diagram showing a state of a frequency band of each signal in each circuit of the signal processing circuit.

[Explanation of symbols]

 2 Original 5 Photoelectric conversion element 5a First sensor pixel row 5b Second sensor pixel row 8, 9 Optical low pass filter

Claims (6)

[Claims] 1. The light reflected by scanning the surface of the original is condensed by an imaging lens and is incident on a photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is detected as an image signal. In the image reading apparatus for obtaining image information by the above, the first sensor pixel array having a spectral distribution characteristic which is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic which covers a wavelength region where the visual has a spectral distribution, and the spectral distribution A photoelectric conversion element including a second sensor pixel row in which read pixels having two different types of spectral distribution characteristics are alternately arranged is provided, and the relative arrangement of the first sensor pixel row and the second sensor pixel row is provided. An image reading apparatus characterized in that the positions are arranged differently in the direction of reflected light from the original. 2. The light reflected by scanning the surface of the original is condensed by an imaging lens and is incident on a photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is detected as an image signal. In the image reading apparatus for obtaining image information by the above, the first sensor pixel array having a spectral distribution characteristic which is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic which covers a wavelength region where the visual has a spectral distribution, and the spectral distribution A photoelectric conversion element having a second sensor pixel row in which read pixels having two different types of spectral distribution characteristics are alternately arranged is provided, and the first sensor pixel row and the second sensor pixel row are relatively arranged. An image reading apparatus characterized in that positions thereof are arranged differently in a direction of reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row and the second sensor pixel row. .. 3. The light reflected by scanning the surface of the original is condensed by an imaging lens and made incident on a photoelectric conversion element, whereby an electric signal corresponding to the reflectance of the original is detected as an image signal. In the image reading apparatus for obtaining image information by the above, the first sensor pixel array having a spectral distribution characteristic which is almost equal to the visual characteristic of the naked eye or a spectral distribution characteristic which covers a wavelength region where the visual has a spectral distribution, and the spectral distribution A photoelectric conversion element having a second sensor pixel row in which read pixels having two different types of spectral distribution characteristics are alternately arranged is provided, and the first sensor pixel row and the second sensor pixel row are relatively arranged. An image reading apparatus characterized in that positions thereof are arranged differently in a direction of reflected light from the original, and an optical low-pass filter is arranged in front of the first sensor pixel row. 4. A calculation means is provided for calculating a high frequency component included in an image read output of the first sensor pixel column as a high frequency component of an R signal, a G signal and a B signal. The image reading device according to claim 1, 2, or 3. 5. The image reading apparatus according to claim 1, wherein the shape of each reading pixel of the second sensor pixel row is formed to be inclined with respect to the main scanning direction. 6. The reading pixel of each of the first sensor pixel row and the second sensor pixel row is formed so as to be inclined with respect to the main scanning direction, as claimed in claim 1, 2, 3, or 4. Image reading device.