JP3203020B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus using a CCD line sensor and capable of high-speed, high-definition reading.

[0002]

2. Description of the Related Art In recent years, scanners capable of high-speed, high-definition reading have been desired. In addition, CCD line sensors that can operate at high speed,
D line sensor has appeared. As an image reading apparatus using a CCD line sensor, for example,
As disclosed in Japanese Patent Publication No. 538, a method has been developed in which a document is divided into a plurality of areas, and a plurality of line sensors corresponding to the respective areas are arranged in the main scanning direction to read a document image. To increase the reading speed and reading density.

[0003]

However, the conventional image reading apparatus using one CCD line sensor is not sufficient in terms of high speed and high definition, and it is difficult to read at high speed and high definition. In order to achieve the above, it is required that the CCD drive circuit and the output signal processing circuit can operate at high speed, which is disadvantageous not only in cost but also in the accuracy of pixel information to be read. Further, in the conventional example, when reading a document smaller than the maximum document size that can be read, all pixel information including unnecessary pixel information among the pixel information of the CCD line sensor is read,
The reading efficiency is poor due to processing.

[0004]

According to the first aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and a photoelectric conversion of the formed reflected light. An image reading apparatus comprising: two photoelectric conversion elements, a driving unit that drives these photoelectric conversion elements, and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element.
A light-shielding plate disposed in front of the photoelectric conversion element so as to block reflected light from other than the original; and an original position corresponding to a pixel to be read first of the photoelectric conversion element is mainly located in the original area. The directions of the document positions substantially at the center of the scanning direction and corresponding to the pixels to be subsequently read are opposite to each other, and are shielded by the light shielding plate.
Driving means for driving the photoelectric conversion element so as to read only the non- existing portion, and a first means for holding the output portion of the pixel only in the transfer portion without the photosensitive portion in the dark output signal over one line
Holding means, and second holding means for holding an output portion of a pixel whose light-sensitive portion is light-shielded,
Normalization means for normalizing the dark output signal over one line based on the output values of the first and second hold means, and a first storage for storing the normalized dark output signal over one line. Means, a second storage means for storing an output of a pixel having a light-shielded light-sensitive portion, and a dark time generated in each pixel by multiplying an output of the first storage means by an output of the second storage means. A first dark output signal generating means for generating an output signal; and a second dark output signal for actually generating a dark output signal output from the photoelectric conversion element based on an output of the first dark output signal generating means. Time output signal generation means, subtraction means for subtracting the output of the second dark time output signal generation means from the output when the image is read, and two data output in parallel in opposite directions from the center of the original image Columns in order from the data at the end of the original image And rearranging means for outputting as a single serial data string arrayed provided in said signal processing means.

According to a second aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising: driving means for driving these photoelectric conversion elements; and signal processing means for performing signal processing on output signals of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. A light-shielding plate disposed in front of the element, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is substantially at the center of the document area in the main scanning direction, and is subsequently read. storage means for direction of the original position corresponding to the read pixel is opposite to each other, and stores the output signal when the dark over only a portion which is not shielded by the light shielding plate to read one line, the light in the photosensitive unit Holding means for holding the output of the pixel which has been subjected to the hold, and multiplying the output of the holding means by the output of reading the contents of the storage means over one line to generate a dark output signal generated in each pixel. A first dark output generation means, a second dark output generation means for generating a dark output signal actually output from the photoelectric conversion element based on an output of the first dark output generation means, Second
Subtraction means for subtracting the output of the dark-time output generation means from the output when the image is read; and two data strings output in parallel in opposite directions from the center of the document image in order from the end data of the document image. And a rearranging means for outputting as a serial data string arranged in the signal processing means.

According to a third aspect of the present invention, there is provided an illumination light source for illuminating a document, image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. A light-shielding plate disposed in front of the element, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is substantially at the center of the document area in the main scanning direction, and is subsequently read. Driving means for driving the photoelectric conversion element so that the directions of the document positions corresponding to the read pixels are opposite to each other, and only the portion not shielded by the light shielding plate is read.
Holding means for holding the output of the pixel only in the transfer part without the photosensitive part, peak holding means for holding the peak value of the output signal when reading the white reference plate over one line, the holding means and the peak hold First normalizing means for normalizing a white reference plate reading signal and an image reading signal over one line on the basis of the output value of the means, and a normalized white reference plate reading signal output from the first normalizing means. Storage means for storing over one line, and second normalizing means for normalizing the normalized image reading signal output from the first normalizing means by the output of reading the content of the storage means over one line And output two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image. And Runamikawa means provided in said signal processing means.

According to a fourth aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit; Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels to be subsequently read are opposite to each other.
Only the portion that is not shaded by the light-shielding plate is read, the intensity of the illumination light source and the sub-scanning speed are controlled, and the output portion of the pixel only in the transfer portion without the photosensitive portion in the dark output signal over one line is held. First holding means, a second holding means for holding an output portion of a pixel having a light-shielded photosensitive portion, and a dark output over one line based on the output values of the first and second holding means. Normalization means for normalizing the signal, first storage means for storing a dark output signal over one line normalized by the normalization means, and storing the output of a pixel having a light-shielded photosensitive portion. A first dark output signal for generating a dark output signal generated in each pixel by multiplying an output of the second storage means and an output read over one line of the first storage means. Generation means A second dark output signal generating means for generating a dark output signal actually output from the photoelectric conversion element based on an output of the first dark output signal generating means; and a second dark output signal. Subtracting means for subtracting the output of the generating means from the output at the time of reading; and one serial line in which two data strings output in parallel in opposite directions from the center of the original image are arranged in order from the data at the end of the original image. And a rearranging means for outputting the data as a data string are provided in the signal processing means.

According to the fifth aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising: driving means for driving these photoelectric conversion elements; and signal processing means for performing signal processing on output signals of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising: a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit. Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels to be subsequently read are opposite to each other.
A storage means for reading out only the portion not shielded by the light shielding plate, controlling the intensity of the illumination light source and the sub-scanning speed, and storing a dark output signal over one line, and a light shield for the photosensitive portion. Holding means for holding the output of a pixel; and a first dark output for generating a dark output signal generated at each pixel by multiplying the output of the holding means and the output of reading the contents of the storage means over one line. Signal generating means, second dark output signal generating means for generating a dark output signal actually output from the photoelectric conversion element based on the output of the first dark output signal generating means, and the second dark output signal generating means. Subtraction means for subtracting the output of the dark output signal generation means from the output when the image is read, and two data strings output in parallel in opposite directions from the center of the original image from the data at the end of the original image In order And rearranging means for outputting as a single serial data stream but provided within the signal processing means.

According to a sixth aspect of the present invention, there is provided an illumination light source for illuminating a document, image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit; Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels to be subsequently read are opposite to each other.
A holding unit for reading out only the portion not shaded by the light shielding plate, controlling the intensity of the illumination light source and the sub-scanning speed, and holding the output of the pixel only in the transfer portion without the photosensitive portion, and a white reference for one line Peak holding means for holding a peak value of an output signal when reading a plate, and a white reference plate reading signal and an image reading signal over one line are normalized with reference to the output values of the holding means and the peak holding means. A first normalizing means, and a normalized white reference plate reading signal output from the first normalizing means
Storage means for storing the data over the line, and second normalization means for normalizing the normalized image reading signal output from the first normalization means by the output of reading the content of the storage means over one line. Reordering means for outputting two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image; Provided.

[0010] In the invention according to claim 7, claims 1, 3
In the inventions described in the fourth and sixth aspects, the accumulation time when the dark output signal over one line is read from the two photoelectric conversion elements is
It is set to be longer than the accumulation time per line when reading an image.

[0011]

According to the first aspect of the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light-shielding plate shields the reflected light from the source other than the original and outputs the two photoelectric conversion elements. almost outputted Moreover the output direction from the center is a backward light shielding plate One signal is the original image
And only those portions that are not shaded are output, and those two output signals are the output signals of the pixel without the light receiving portion of the photoelectric conversion element and the pixel that is optically shielded and stored in advance for dark output correction. A dark output generated for each pixel is generated by multiplying the dark output pattern for one line normalized by the above with the representative output value of the pixel in the light shield portion, and the photoelectric output is actually calculated from the dark output of each pixel. The dark output output from the conversion element is generated and the value is subtracted from the output value of the photoelectric conversion element, and the output data is rearranged as one serial data sequence arranged in order from the data at the end of the document image. Accordingly, when the driving frequency of the photoelectric conversion element is the same and the reading density is the same as compared with the case where only one photoelectric conversion element is used, one line can be read at twice the speed. In addition, when the driving frequency of the photoelectric conversion element is the same and the reading speed of one line is the same, reading can be performed at twice the reading density, and there was a dark output remaining on the previous main scanning line. In this case, the dark output can be accurately corrected. Further, since the output data is output as one serial data arranged in order from the data at the end of the original image, it is possible to obtain the output data in the same output format as when one photoelectric conversion element is used.

According to the second aspect of the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light-shielding plate shields the reflected light from other than the original and outputs the two photoelectric conversion elements. One of the signals output from the approximate center addition output direction thereof of the document image is reverse the
Only the part that is not shaded by the shade plate is output, and
The output signal is multiplied by the output value output from the storage means and the representative output value of the light shield part to generate a dark output generated in each pixel, and the photoelectric conversion element is actually obtained from the dark output of each pixel. , And subtracts the value from the output value of the photoelectric conversion element, and the output data is rearranged as one serial data sequence arranged in order from the data at the end of the document image. This makes it possible to read one line at twice the speed when the driving frequency of the photoelectric conversion element is the same and the reading density is the same as compared with the case where one photoelectric conversion element is used. Further, when the driving frequency of the photoelectric conversion element is the same and the reading speed of one line is the same, reading can be performed at twice the reading density, and when there is a dark output remaining in the previous main scanning line. However, the dark output can be accurately corrected. Further, since the output data is output as one serial data arranged in order from the data at the end of the document image, the output data can be obtained in the same output format as when one photoelectric conversion element is used.

According to the third aspect of the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light shielding plate shields the reflected light from other than the original and outputs the two light output from the photoelectric conversion element. One of the signals output from the approximate center addition output direction thereof of the document image is reverse the
Only the portion that is not shaded by the shading plate is output, the output signal is subjected to dark output correction, and then the image reading signal is normalized by the output from the storage unit that stores the white reference plate reading signal. The output data is rearranged as one serial data string arranged in order from the data at the end of the document image. This makes it possible to read one line at twice the speed when the driving frequency of the photoelectric conversion element is the same and the reading density is the same as compared with the case where one photoelectric conversion element is used. Further, when the driving frequency of the photoelectric conversion element is the same and the reading speed of one line is the same, reading can be performed at twice the reading density, and when there is a dark output remaining in the previous main scanning line. However, it is possible to accurately perform dark output correction. Further, even when there is a variation in sensitivity between the pixels of the photoelectric conversion element or when there is a variation in the intensity of the illumination light source, the image can be read with high accuracy, and the output data is the original image. Are output as one serial data arranged in order from the end data, so that it is possible to obtain output data in the same output format as when one photoelectric conversion element is used.

According to the fourth aspect of the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light shielding plate is provided with a light shielding plate for shielding reflected light from sources other than the original depending on the size of the original. Moving, illumination light source control means,
The sub-scanning speed control means controls the illumination light source and the sub-scanning speed in accordance with the size of the original, and two signals output from the two photoelectric conversion elements are output from substantially the center of the original image, and the output directions thereof are in opposite directions. And is shielded by the light shielding plate.
Is only have no portion is outputted, also, the output signal is normalized by the output signal of the pixel that is a pixel and the light shield is not receiving portion of the photoelectric conversion element which is stored in advance for dark signal correction The dark output pattern for one line is multiplied by the representative output value of the pixel in the light shield part to generate the dark output generated in each pixel, and the dark output of each pixel is actually output from the photoelectric conversion element. To generate a dark output to be subtracted from the output value of the photoelectric conversion element,
Further, the output data is rearranged as one serial data sequence arranged in order from the data at the end of the document image. This makes it possible to read one line at twice the speed when the driving frequency of the photoelectric conversion element is the same and the reading density is the same as compared with the case where one photoelectric conversion element is used. In the case where the driving frequency is the same and the reading density of one line is the same, reading can be performed at twice the reading density. Further, when reading a small document, high-speed reading can be performed, and even when there is a dark output remaining on the immediately preceding main scanning line, the dark output can be accurately corrected. Further, since the output data is output as one serial data string arranged in order from the data at the end of the document image, the output data can be obtained in the same output format as when one photoelectric conversion element is used.

According to the fifth aspect of the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light shielding plate is provided with a light shielding plate for shielding reflected light from sources other than the original depending on the size of the original. Moving, illumination light source control means,
The sub-scanning speed control means controls the illumination light source and the sub-scanning speed in accordance with the size of the original, and two signals output from the two photoelectric conversion elements are output from substantially the center of the original image, and the output directions thereof are in opposite directions. And is shielded by the light shielding plate.
Only the unexposed portion is output, and the output signal is multiplied by the dark output value output from the storage means and the representative output value of the pixel in the light shield portion to generate a dark output generated in each pixel. Then, the dark output actually output from the photoelectric conversion element is generated from the dark output of each pixel, and the output value is subtracted from the output value of the photoelectric conversion element. Further, the output data is rearranged as one serial data sequence arranged in order from the data at the end of the document image. This makes it possible to read one line at twice the speed when the driving frequency of the photoelectric conversion element is the same and the reading density is the same, as compared with the case where one photoelectric conversion element is used. When the reading speed is the same and the reading speed of one line is the same, reading can be performed at twice the reading density, and when a small document is read, higher-speed reading can be performed. In addition, even when there is a dark output remaining on the immediately preceding main scanning line, the dark output can be corrected with high accuracy. Further, since the output data is output as one serial data sequence arranged in order from the data at the end of the document image, the output data can be obtained in the same output format as when one photoelectric conversion element is used.

In the present invention, the two photoelectric conversion elements are independently and simultaneously driven by the driving means, and the light shielding plate is provided with a light shielding plate for shielding reflected light from other than the original depending on the size of the original. Moving, illumination light source control means,
The sub-scanning speed control means controls the illumination light source and the sub-scanning speed in accordance with the size of the original, and two signals output from the two photoelectric conversion elements are output from substantially the center of the original image, and the output directions thereof are in opposite directions. And is shielded by the light shielding plate.
Only the portion which is not output is output, and the output signal is subjected to the dark output correction, and then the image reading signal is normalized by the output from the storage means for storing the white reference plate reading signal. The output data is rearranged as one serial data string arranged in order from the data at the end of the document image. This makes it possible to read one line at twice the speed when the driving frequency of the photoelectric conversion element is the same and the reading density is the same as compared with the case where one photoelectric conversion element is used. When the reading speed is the same and the reading speed of one line is the same, reading can be performed at twice the reading density, and when a small document is read, higher-speed reading can be performed. In addition, even when there is a dark output remaining in the immediately preceding main scanning line, the dark output can be accurately corrected. It is possible to accurately read an image even when there is a variation in the intensity of the light source. Further, since the output data is output as one serial data string arranged from the data at the end of the document image, the output data can be obtained in the same output format as when one photoelectric conversion element is used.

According to the seventh aspect of the present invention, the storage time for reading out the dark output signal over one line from the photoelectric conversion element is made longer than the storage time per line for image reading, so that each pixel can be read. Since the dark output is integrated, the white noise at the time of capturing the dark output can be reduced, and the dark output can be captured at a high level, thereby reducing deterioration during signal processing. This makes it possible to perform highly accurate dark output correction.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. In this embodiment,
By using two photoelectric conversion elements, high-speed and high-definition reading is possible, and the output format is the same as that of one photoelectric conversion element. It is intended to provide an image reading apparatus capable of accurately correcting the dark output even when the image reading is performed.

First, the overall configuration of the image reading apparatus will be described with reference to FIG. An original 2 is placed on the contact glass 1, and the original 2 is linearly illuminated by an illumination light source 3. The reflected light on the left side from the center of the document 2 is imaged on the CCD line sensor 5a as the photoelectric conversion element via the imaging lens 4a as the image forming means on the left side, and the reflected light on the right side from the center of the document 2 is An image is formed on a CCD line sensor 5b as a photoelectric conversion element via an imaging lens 4b as an image forming means on the right side. In this case, the output units of the two CCD line sensors 5a and 5b are arranged outward so that the image signal of the central part of the linearly illuminated image is output first. Further, the light shielding plates 6a and 6b shield light reflected from areas other than the reading area. Note that FIG.
In addition to the optical system described above, any optical system that can divide a document image into two in the main scanning direction may be used, for example, a method using a mirror, a half mirror, or a roof mirror. .

Next, the state of the photoelectric conversion system, drive system and signal processing system inside the circuit of FIG. 2 will be described with reference to FIG. The CCD line sensors 5a and 5b include photodiode arrays 7a and 7b, CCD shift registers 8a and 8
b, output units 9a and 9b. The CCD line sensors 5a and 5b are connected to a CCD driving unit 10 as driving means. The CCD driving unit 10 includes a document size detecting unit 11 serving as a document size detecting unit.
Is connected. A sub-scanning speed control unit 12 as sub-scanning speed control unit, an illumination light source control unit 13 as illumination light source control unit, and a signal processing unit 14 as signal processing unit are connected to the document size detection unit 11. I have. The light shielding plates 6a and 6b are controlled by the light shielding plate control unit 15. In the present embodiment, the internal configuration of the signal processing unit 14 is characterized by a feature, but a detailed description of this internal configuration will be described later.

In such a configuration, the CCD line sensors 5a and 5b photoelectrically convert the incident light by the photodiode arrays 7a and 7b, and receive the accumulated signal charges by receiving the shift pulse from the CCD driving section 10 in parallel with the CCD shift registers. 8a and 8b. Next, the CCD shift registers 8a and 8b receive the transfer pulses of the CCD drive unit 10 and sequentially send the pixel signals to the output units 9a and 9b to send out signals for one pixel. Is repeated by the number of pixels of one line of the sensor, whereby the pixel signal of one line (sensor) can be read. The CCD line sensors 5a and 5b are independently and simultaneously driven by a CCD drive unit 10, and output signals are output to a signal processing unit 14.
, Sipele hold, A / D conversion, dark output correction,
Processing such as rearrangement, shading correction, and the like, in which two data strings output in parallel in opposite directions from the center of the document image are output as one serial data string sequentially arranged from the data at the end of the document image, are performed. . A detailed description of the operation processing of the signal processing unit 14 will be described later. Then, the illumination light source 3, the CCD line sensors 5a, 5
b, the imaging lenses 4a and 4b are integrally mounted on a carriage (not shown), and move to the next reading position when reading of one line is completed. FIG. 4 shows the shift pulse SH and the clock pulse φ output from the CCD driving unit 10.
1, φ2, and the timing of the reset pulse RS.

Here, when reading an original 2 smaller than the maximum readable original size, portions where reflected light having image information from the original 2 does not enter are shielded by light shielding plates 6a and 6b.
The pixels from the first to the m-th read pixels having the document image information are read, and the pixels of the document 2 having no image information are not read. For this purpose, the document size detector 11 automatically detects the document size (main scanning direction X) or detects the document size (main scanning direction) designated by a person, and uses the size to detect the CCD line sensor 5.
The required number m of pixels a and 5b is set. The information on the set number of pixels is sent to the CCD drive unit 10, the signal processing unit 14, the illumination light source control unit 13, the sub-scanning speed control unit 12, and the light shielding plate control unit 15. The light shielding plate control unit 15 outputs m and outputs φ1 and φ2 so as to read m pixels of the CCD line sensors 5a and 5b in accordance with the transmitted information on the number of pixels, and then outputs a shift pulse SH. The signal processing unit 14 performs signal processing on the assumption that the number of pixels in one line is 2 m. The sub-scanning speed control unit 12 determines the sub-scanning speed according to the transmitted information on the number of pixels and performs sub-scanning. In this case, since the reading time of one line is m / n times, the sub-scanning speed is made n / m times as compared with the case where all the pixels n are read. The illumination light source control unit 13 determines the intensity of the illumination light source 3 according to the transmitted information on the number of pixels, and drives the illumination light source 3. In this case, since the reading time of one line is m / n times, the exposure amount of the CCD line sensor is also reduced to m / n times as it is. Therefore, the illumination light source 3 is controlled so that the illuminance becomes n / m times as compared with the case where all the pixels n are read.

As described above, the CCD line sensor 5
a and 5b are driven independently and simultaneously, so that the CCD line sensors 5a and 5b are different from the conventional case where one CCD line sensor 5a and 5b is used.
And the same reading density, it is possible to read one line at twice the speed. When the driving frequencies of the CCD run sensors 5a and 5b are the same and the reading speed of one line is the same, the reading can be performed at twice the reading density. , The output data can be obtained in the same output format as when one CCD line sensor is used as in the related art. Further, since the pixels that do not contribute to the reading are not read using the light shielding plates 6a and 6b, the reading speed can be increased when reading a small document. The power consumption of driving the elements can be reduced by increasing the clock speed of the CCD line sensors 5a and 5b by m / n times without changing the brightness of the illumination and the sub-scanning speed at all. Also, the brightness of the illumination, the sub-scanning speed, the CCD line sensor 5
The total data amount can be reduced by reading out only the pixels related to image reading without changing the clock speeds of a and 5b at all, and not reading out the pixels not related without sending the clock.

Next, in this embodiment, the signal processing unit 1
Although the operation of the internal processing of No. 4 has a feature, the reason why the signal processing unit 14 has the feature will be described before starting the description. In the image reading apparatus as described above,
The outputs of the CD line sensors 5a and 5b appear as a sum of an output corresponding to the exposure amount and a dark output generated regardless of the exposure amount. Further, by reading out only the pixels related to the image reading out of the pixels of the CCD line sensors 5a and 5b, the photoelectric conversion output corresponding to the exposure amount includes the dark output generated at the pixel and the output before the previous line. Appears in the form of a sum with the dark output generated in the non-read pixel at the time of reading. FIG. 5 shows how the dark outputs overlap when 25% of the pixels of the CCD line sensors 5a and 5b are read. CCD line sensors 5a and 5b having CCD shift registers 8a and 8b for n pixels when there is no change in the dark output during one reading of the original image.
When only m pixels are read out of the i-th line, the j-th pixel output dout (i, j) of the i-th line is represented by the following equation.

Dout (i, j) = dmo (i, j) + {{dbk (j + m (h−1))} (1) where dmo (i, j) is the i-th line and the j-th image Signal dbk (k): When darkness is generated at the k-th pixel of the sensor and k> n, dbk (k) = 0. Therefore, in order to convert the information of the document 2 into an electric signal with high accuracy. Any correction for reducing the dark output with respect to the output signals of the CCD line sensors 5a and 5b, and C
Sensitivity variation between pixels of the CD line sensors 5a and 5b,
Shading correction for correcting unevenness of the intensity distribution of the illumination light source 3 is required. Further, in the present embodiment, it is necessary to perform output data rearrangement processing together with dark output correction and shading correction. For this reason, the signal processing unit 14 has a configuration described below.

Therefore, the internal configuration of the signal processing unit 14 will now be described with reference to FIG. The above-described image reading apparatus shown in FIGS. 2 and 3 has a circuit configuration described below. That is, in this device,
S / H (sample and hold) circuit 15a, and 15b, shielding
Only the portion not shielded by the light plates 6a and 6b is read out.
S / H circuits 16a and 16b as first holding means for holding an output portion of a pixel having only a transfer portion without a photosensitive portion among dark output signals over a line, and a pixel having a light shield in the photosensitive portion S / H circuits 17a and 17b as second holding means for holding the output portion of
Peak hold circuits 18a and 18b and amplifying circuit 19
A, 19b, switch circuits 20a, 20b, and A / D as normalizing means for normalizing a dark output signal over one line based on the output values of the S / H circuits 16a, 16b, 17a, 17b. Conversion circuits 21a and 21b, switch circuits 22a and 22b, dark output memories 23a and 23b as first storage means for storing the normalized dark output signals over one line, and a light shield on the photosensitive portion. Averaging circuits 24a and 24b as second storage means for storing the outputs of the pixels subjected to the averaging, and the outputs of the dark output memories 23a and 23b and the averaging circuit 24
multiplication circuits 25a and 25b as first dark output signal generation means for multiplying the outputs of the pixels a and 24b to generate dark output signals generated in the respective pixels, and based on the outputs of the multiplication circuits 25a and 25b. Addition circuits 26a and 26b as second dark output signal generation means for generating dark output signals actually output from the CCD line sensors 5a and 5b, and a memory 27
a, 27b; subtraction circuits 28a, 28b as subtraction means for subtracting the outputs of the adders 26a, 26b and the memories 27a, 27b from the output when the image is read; switch circuits 29a, 29b; ,
White reference memories 30a and 30b connected to the subsequent stage of 29b
And dividers 31a and 31b, and a reordering means for outputting two data strings output in parallel in opposite directions from the center of the document image as one serial data string arranged in order from the data at the end of the document image. And a rearrangement circuit 32 serving as a rearrangement circuit.

In such a configuration, the operation processing of the signal processing unit 14 in FIG. 1 will be described. One line of the output of the CCD line sensors 5a and 5b is, for example, as shown in FIG.
The waveform is as shown in FIG. DS in FIG. 6 (a)
(E) is the output of the pixel only in the transfer section without the photosensitive section, DS
(S) shows the output of the pixel having the light-shielded photosensitive portion, and the read output of the original 2 following this. These one-line waveforms are guided to S / Hs 15a and 15b, and the transfer clock waveforms of the CCD line sensors 5a and 5b are removed.
The waveform shown in FIG. In this embodiment, the write address and read address of each memory are reset before all signal processing. Next, generation and storage of dark output over one line are performed. For this reason, the switch circuits 20a, 20
b is switched to the side opposite to the side shown in FIG.
The outputs of a and 15b are S / H circuits 16a and 16b and S / H
Circuits 17a and 17b and A / D conversion circuits 21a and 21b
It is led to. CCD line sensor 5 over one line
When the exposure amounts of a and 5b are set to zero, the output of one line passes through the S / H circuits 15a and 15b to have a waveform as shown in FIG. That is, the DS (S) and the reading area all have the dark output level, and the values vary from pixel to pixel. This is led to S / H circuits 16a and 16b, and DS
A / D conversion circuit 21 samples and holds the value of (E).
The upper limit reference VrefH of a and 21b is set. Also, S
/ H circuits 17a and 17b, sample and hold at the average value or representative value of DS (S), and amplify circuits 19a and 19b.
The signal is amplified by b and set to the lower limit reference value VrefL of the A / D conversion circuits 21a and 21b. That is, the A / D conversion 21
FIG. 7A shows the relationship between the reference VrefH and VrefL and the signal input (S / H circuits 17a and 17b). As a result, A / D conversion is performed, and the output is stored in dark output memories 23a and 23b (having a memory area of one line or more of CCD line sensors 5a and 5b) with switching circuits 22a and 22b as lower switching positions. One line (n pixels of the CCD line sensor) is stored. This completes the capture of the dark output pattern for one line based on the average value or the representative value of the pixels DS (S) of the light-shielded photosensitive section. The dark output pattern is: dbk (j) / dbk (2) where dbk (j): dark output signal of the j-th pixel in dark output reading dbk: DS (S) in dark output reading ) Is a representative value or average value, and is a value indicating how many times the output level of each pixel of each read line in darkness is higher than the output of a pixel having a light-shielded photosensitive portion. Thereafter, the dark output memories 23a and 23b
Are reset.

Next, the white reference of one line is taken. At the time of taking in the white reference, all the pixel signals of the CCD line sensors 5a and 5b are output at the time of taking in the dark output pattern, so that there is no remaining dark output. The switch circuits 20a and 20b for taking in the white reference are set to the switching positions shown in FIG. 1, and the outputs of the S / H circuits 15a and 15b are input to the peak hold circuits 18a and 18b to read the white reference first. Is held, and this is set as the lower limit value VrefL of the A / D conversion circuits 21a and 21b. S / H circuit 15 when reading the white reference next time
a and 15b are output to S / H circuits 16a and 16b.
A / D conversion circuit 2 samples and holds the value of S (E).
The upper limit reference values VrefH of 1a and 21b are set. Thereby, the reference V of the A / D conversion circuits 21a and 21b is
The relationship between refH, VrefL and the signal input (= output of S / H 15a, 15b) is as shown in FIG. 7 (b). A / D conversion is performed in such a setting, and the output is dwo (j) / (VrefH-VrefL) + dbk (j) / (VrefH-VrefL) = {dwo (j) + dbk (j)} / (VrefH- VrefL) (3) where dwo is a photoelectric conversion output when the white reference is read. This is the position where the switching circuits 22a and 22b are at the positions shown in FIG. 1, and the averaging circuits 24a and 24b and the subtraction circuits 28a and
28b. The averaging circuits 24a and 24b have a function of sequentially adding input pixel outputs to obtain an average value when an input control signal is ON, and hold the value as it is after obtaining the average value. I do. In this case DS (S)
The control signal which is turned on when the value of is supplied. Since the photoelectric conversion output dwo (j) during this time is zero, the outputs of the averaging circuits 24a and 24b become dbk, which is the average or representative value of DS (S), and this value is obtained by the following white reference reading. The signals are input to the multiplication circuits 25a and 25b. The other inputs of the multiplying circuits 25a and 25b are the outputs (Equation (2)) from the dark output memories 23a and 23b. As a result, the outputs of the multiplying circuits 25a and 25b are: ｛dbk / (VrefH−VrefL) )}. {Dbk (j) / dbk} = dbk (j) / (VrefH-VrefL) (4) This output is input to addition circuits 26a and 26b (having a memory area for one line or more of CCD line sensors 5a and 5b), and the sum of the output and the outputs of memories 27a and 27b is output from addition circuits 26a and 26b. However, in this case, the memories 27a and 27b are initially reset, and the recorded data is all zero. Therefore, the multiplication circuit 2 is output from the addition circuits 26a and 26b.
The outputs (expression (4)) of 5a and 25b are output as they are. This output is guided to the negative input (-) of the subtraction circuits 28a and 28b. On the other hand, equation (3) is input to the positive input (+) of the subtraction circuits 28a and 28b. As a result, the outputs of the subtraction circuits 28a and 28b are dwo (j) / (VrefH-VrefL) (5) from the equations (3)-(4). Each calculation of the white reference reading is performed by the number of readout pixels (m pixels in each sensor). This output (Equation (5))
Is stored in the white reference memories 30a and 30b as the switching positions opposite to those shown in the switching circuits 29a and 29b. Thus, the capturing of the white reference of one line (m pixels in each sensor) is completed. Thereafter, the write addresses and read addresses of the dark output memories 23a and 23b, the memories 27a and 27b, and the white reference memories 30a and 30b are reset.

Next, after the white reference of one line has been read, the CCD line sensors 5a and 5
All the pixels of b are output. As a result, immediately before image input is performed, the residual dark output of all the pixels of the CCD line sensors 5a and 5b disappears. Image input is A
The processing up to the output of the / D conversion circuits 21a and 21b is performed in the same manner as the above-described white reference. That is, the relationship between the two references VrefH and VrefL of the A / D conversion circuits 21a and 21b and the input is shown in FIG.

Hereinafter, the difference between the white reference input and the image input will be described. The control signal input to the averaging circuits 24a and 24b is turned ON only when the value of the input DS (S) of the first line is ON. Therefore, the averaging circuits 24a, 24
The value b is held and output when reading an image is the average value of DS (S) dbk / (VrefH-VrefL) when reading the first line. Next, the dark output memories 23a and 23b output signals in the dark output pattern (formula (2)) in order from the first to the nth, and the number of pixels (n pixels) of one CCD line sensor 5a, 5b ) And then output zero. Therefore, the outputs of the multiplication circuits 25a and 25b are n
Expression (2) is performed until a signal for a pixel is output, and n + 1
It is zero after the pixel. On the other hand, the memories 27a, 27
In the 7b read operation, the read address is reset after outputting the first to m-th signals which are the number of read pixels of one CCD line sensor. In the write operation, the outputs of the adders 26a and 26b are written in order from the first to the mth, and after the mth is written, the write address is reset. Therefore, {dbk (j + m (h-1))} (6) is led to the negative inputs of the subtraction circuits 28a and 28b. This is the dark output of the j-th pixel when reading the i-th line. On the other hand, the positive side inputs of the subtraction circuits 28a and 28b include dmo (i, j) / (VrefH−VrefL) + {{dbk (j + m (h−1))} / (VrefH−VrefL) = [dmo (i, j) + {{dbk (j + m (h-1))}] / (VrefH-VrefL) (7) Therefore, the outputs of the subtraction circuits 28a and 28b are as follows: dmo (i, j) / (VrefH-VrefL) (8), and it is possible to extract only the image signal from which the dark output has been removed. Next, the output is connected to the switch circuit 29a,
29b is the switching position shown in FIG.
31b, and the white reference memories 30a, 30
The division is performed by the output from reading b. As a result, the outputs of the division circuits 31a and 31b are given by (Equation (8)) / ((5)
According to the equation, dmo (j) / dwo (j) is obtained, and data subjected to dark output correction and shading correction is output. The two data output in parallel in the opposite direction from the center of the original image are input to the rearrangement circuit 32 and output as one serial data sequence arranged in order from the data at the end of the original 2. That is, the data sequence before the rearrangement is performed as shown in FIGS.
The two parallel data strings are arranged as shown in FIG. 8, but are converted and output in the rearrangement circuit 32 as shown in FIG. 8C.

As described above, in this embodiment, 1
In the case where the dark output and the light source intensity do not fluctuate during the reading period, the quantization is performed without being affected by the dark output even if the dark output before the previous line reading remains.
Shading correction can be performed, and by rearranging, output data can be obtained in the same output format as when one CCD line sensor is used.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, high-speed and high-definition reading is possible by using two photoelectric conversion elements, and the output format is the same as that of one photoelectric conversion element. It is an object of the present invention to provide an image reading apparatus capable of accurately correcting dark output even when reading is performed with a small number of pixels.

That is, in this embodiment, the signal processing unit 14
Is changed, and only the signal processing unit 14 will be described here. The description of the same parts as in the first embodiment is omitted, and the same reference numerals are used for the same parts.

First, the main components of the signal processing section 14 in this embodiment will be described with reference to FIG. In the signal processing unit 14, light is not shielded by the light shielding plates 6a and 6b.
Dark output memories 23a and 23b as storage means for reading out only the dark portions and storing dark output signals over one line.
And an averaging circuit 24 as a holding means for holding an output of a pixel having a light-shielded photosensitive portion.
a, 24b, and the outputs of the averaging circuits 24a, 24b and the output of reading the contents of the dark output memories 23a, 23b over one line to generate dark output signals generated in the respective pixels. Multiplying circuits 25a and 25b as first dark output generating means, and the multiplying circuits 25a and 25b
Adder circuits 26a and 26b as second dark output generation means for generating dark output signals actually output from the photoelectric conversion elements 5a and 5b based on the outputs of
b, the adders 26a, 26b and the memories 27a,
Subtraction circuits 28a and 28b as subtraction means for subtracting the output of the original image 27b from the output when the image is read; and two data strings output in parallel in opposite directions from the center of the original image to the ends of the original image. A rearrangement circuit 32 as a rearrangement circuit for outputting a serial data sequence arranged in order from the data is provided in a circuit configuration as shown in FIG.
The description of the other circuit configurations is omitted.

In the above-described signal processing unit 14 of FIG. 9, the circuit configuration up to the subtracters 28a and 28b is the same as that of the above-described signal processing unit 14 of FIG. 1, but the configuration of the subsequent circuit parts is different. That is, the outputs of the subtraction circuits 28a and 28b are input to the rearrangement circuit 32, and the two parallel data strings are rearranged as one serial data line arranged from the data at the end of the document image. Therefore, the switching circuit 29,
One white reference memory 30 and one division circuit 31 are provided. Further, in the signal processing unit 14 of FIG. 9, shading correction is performed after the rearrangement circuit 32, and the other parts have the same configuration as that of FIG. Therefore, also in this embodiment, the same effects as those of the above-described first embodiment can be obtained, and the circuit configuration for performing the shading correction can be simplified.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, by using two photoelectric conversion elements, high-speed and high-definition reading is possible, and the output format is the same as that of the image reading apparatus using one photoelectric conversion element. It is an object of the present invention to provide an image reading apparatus capable of accurately correcting variations in sensitivity between pixels and variations in intensity distribution of illumination light sources.

That is, in this embodiment, the signal processing unit 14
Is changed, and only the signal processing unit 14 will be described here. The description of the same parts as in the first embodiment is omitted, and the same reference numerals are used for the same parts.

First, the main components of the signal processing section 14 in this embodiment will be described with reference to FIG. In the signal processing unit 14, the light is shielded by the light shielding plates 6a and 6b.
S / H circuit 1 as a holding means for reading out only the non- existent portion and holding the output of the pixel only in the transfer portion without the photosensitive portion
6a, 16b, peak hold circuits 18a, 18b as peak hold means for holding a peak value of an output signal when a white reference plate is read over one line, and output values of the hold means and the peak hold means. A / D as first normalizing means for normalizing a white reference plate reading signal and an image reading signal over one line as a reference
Conversion circuits 21a and 21b and the A / D conversion circuit 21
a and 21b, a white reference memory 30 as storage means for storing the normalized white reference plate reading signal over one line, and a normalized white reference plate output signal from the A / D conversion circuits 21a and 21b. A division circuit 31 as a second normalizing means for normalizing an image reading signal by an output obtained by reading the contents of the white reference memory 30 over one line, and a parallel output in the opposite direction from the center of the original image. Two data strings are arranged in order from the data at the end of the original image.
A rearrangement circuit 32 as a rearrangement means for outputting two serial data strings is provided by a circuit configuration as shown in FIG. The description of the other circuit configurations is omitted.

In the signal processing unit 14 shown in FIG.
The circuit configuration up to the / D conversion circuits 21a and 21b is the same as that of the signal processing unit 14 in FIG. 1, but the subsequent circuit configuration is different. That is, the A / D conversion circuits 21a and 21b
Is output from the rearranging circuit 3 via the switching circuits 22a and 22b.
2. The two parallel data strings input to the memories 33a and 33b are rearranged as one serial data string arranged from the data string at the end of the document image. in this case,
When data is directly input to the rearrangement circuit 32, FIG.
As shown in (c), the information of DS (S) is destroyed. Therefore, each of the CCD line sensors 5 is stored in the memories 33a and 33b so as not to destroy the DS (S) information.
The DS (S) information output from a and 5b is stored, and after the data is rearranged, two DS (S) are inserted in the select circuit 34 and converted into data as shown in FIG. And output. Further, in this circuit, the dark output correction and the shading correction are performed after the rearrangement circuit 32. Other processes are performed in the same manner as the signal processing unit 14 in FIG. Therefore, in the case of the present embodiment, the same effect as that of the first embodiment of FIG. 1 can be obtained, and by adopting such a configuration, a circuit configuration for performing the dark output correction and the shading correction can be obtained. It can be simplified.

Next, a first embodiment of the present invention will be described with reference to FIG. In this embodiment, by using two photoelectric conversion elements, high-speed and high-definition reading is possible, and the number of pixels read out from the photoelectric conversion elements is changed in accordance with the reading area. To enable even faster reading,
Further, the image reading apparatus has the same output format as one photoelectric conversion element, and can accurately perform dark output correction even when reading is performed for a smaller number of pixels than the number of pixels of the photoelectric conversion element. Is provided.

That is, in this embodiment, the signal processing unit 14
Is changed, and only the signal processing unit 14 will be described here. In addition, Claims 1, 3,
The description of the same parts as those of the first embodiment of the invention described in 4, 6 is omitted, and the same reference numerals are used for the same parts.

First, the main components of the signal processing section 14 in this embodiment will be described with reference to FIG. In the signal processing unit 14, S / H circuits 16a and 16 as first holding means for holding the output portion of the pixel only in the transfer unit without the photosensitive unit in the dark output signal over one line
b, peak hold circuits 18a and 18b as second holding means for holding an output portion of a pixel having a light-shielded photosensitive portion, and S / H circuits 16a and 18b.
A / D conversion circuits 21a and 21b as normalizing means for normalizing a dark output signal over one line with reference to output values of the 16b and the peak hold circuits 18a and 18b,
Dark output memories 23a and 23b as first storage means for storing one line of dark output signals normalized by the A / D conversion circuits 21a and 21b, and a pixel having a light-shielded photosensitive portion. Averaging circuits 24a and 24b as second storage means for storing the outputs of the averaging circuits 24a and 24b, and multiplying the outputs of the averaging circuits 24a and 24b by the outputs read over one line of the dark output memories 23a and 23b. Multiplying circuits 25a and 25b as first dark output signal generating means for generating dark output signals generated in the respective pixels, and a CCD actually based on the outputs of the multiplying circuits 25a and 25b
Addition circuit 2 as second dark output signal generating means for generating dark output signals output from line sensors 5a and 5b
6a, 26b and memories 27a, 27b, and a subtraction circuit 2 as subtraction means for subtracting the output of the addition circuits 26a, 26b and the memories 27a, 27b from the output when the output is read.
8a and 28b, and a reordering means as a reordering means for outputting two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image. The replacement circuit 32 is provided with a circuit configuration as shown in FIG. The description of the other circuit parts is omitted.

In the signal processing unit 14 of FIG. 11 described above, instead of the dark output memories 23a and 23b in FIG.
A read-only (ROM) dark output memory 35a,
35b is used. Therefore, there is no operation for capturing the dark output, and the elements necessary for this operation are omitted. The storage in the dark output memories 35a and 35b can be processed in the same way as in the configuration of FIG. The signal processing unit 14 can be applied to a case where the dark output pattern is stored to some extent in the CCD run-y sensors 5a and 5b with little change over time. Therefore, in the case of the present embodiment, the same effects as those of the signal processing unit 14 of FIG. 1 are obtained, and the circuit configuration can be simplified since the dark output storage operation and the switching circuit are not required.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, by using two photoelectric conversion elements, high-speed and high-definition reading is possible, and the number of pixels read out from the photoelectric conversion elements is changed in accordance with the reading area. To enable even faster reading,
Further, the image reading apparatus has the same output format as one photoelectric conversion element, and can accurately perform dark output correction even when reading is performed for a smaller number of pixels than the number of pixels of the photoelectric conversion element. Is provided.

That is, in this embodiment, the signal processing unit 14
Is changed, and only the signal processing unit 14 will be described here. In addition, Claims 1, 3,
The description of the same parts as those of the first embodiment of the invention described in 4, 6 is omitted, and the same reference numerals are used for the same parts.

First, the main components of the signal processing section 14 in this embodiment will be described with reference to FIG. In the signal processing unit 14, dark output memories 35a and 35b as storage means for storing dark output signals over one line.
And an averaging circuit 24 as a holding means for holding an output of a pixel having a light-shielded photosensitive portion.
a and 24b are multiplied by the outputs of the averaging circuits 24a and 24b and the output of reading the contents of the dark output memories 35a and 35b over one line to generate a dark output signal generated in each pixel. (1) Multiplying circuits 25a and 25b as dark output signal generating means, and the multiplying circuits 25a and 25b
Adder circuits 26a, 26b, 27a, 2 as second dark output signal generating means for generating dark output signals actually output from the CCD line sensors 5a, 5b based on the outputs of
7b and the adders 26a, 26b, 27a, 27b
Subtracting circuits 28a and 28b as subtracting means for subtracting the output of the original image from the output when the image is read, and two data strings output in parallel in opposite directions from the central portion of the original image to the data at the end of the original image. And a rearrangement circuit 32 as a rearrangement means for outputting as one serial data sequence arranged in order from the above. The description of the other circuit parts is omitted.

In the signal processing section 14 of FIG. 12, the dark output memories 23a, 23a in the signal processing section 14 of FIG.
3b, a dark output memory 35a,
35b is used. Thus, in the case of the present embodiment, the storage operation of the dark output can be eliminated as in the case of FIG. In addition, dark output memory 3
The storage and adaptation conditions for 5a and 35b are the same as in the embodiment of FIG. Accordingly, the signal processing unit 14 in FIG.
The same effect as the signal processing unit 14 of FIG. 9 can be obtained,
In addition, since the dark output storage operation and the switching circuit are not required, the circuit configuration can be simplified.

Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, by using two photoelectric conversion elements, high-speed and high-definition reading is possible, and the number of pixels read out from the photoelectric conversion elements is changed in accordance with the reading area. To enable even faster reading,
It is another object of the present invention to provide an image reading device capable of accurately correcting variations in sensitivity between photoelectric conversion element pixels and intensity distribution of an illumination light source.

That is, in this embodiment, the signal processing unit 14
Is changed, and only the signal processing unit 14 will be described here. In addition, Claims 1, 3,
The description of the same parts as those of the first embodiment of the invention described in 4, 6 is omitted, and the same reference numerals are used for the same parts.

First, the main components of the signal processing section 14 in this embodiment will be described with reference to FIG. The S / H circuit 1 as a holding means for holding the output of the pixel only in the transfer unit without the photosensitive unit in the signal processing unit 14
6a and 16b, peak hold circuits 18a and 18b as peak hold means for holding a peak value of an output signal when a white reference plate is read over one line, the S / H circuits 16a and 16b, and the peak hold A first method for normalizing a white reference plate reading signal and an image reading signal over one line based on the output values of the circuits 18a and 18b.
A / D conversion circuits 21a and 21b as normalizing means;
A white reference memory 30 as storage means for storing the normalized white reference plate read signal output from the A / D conversion circuits 21a and 21b over one line, and the outputs of the A / D conversion circuits 21a and 21b And a dividing circuit 31 as a second normalizing means for normalizing the normalized image reading signal by the output of reading the contents of the white reference memory 30 over one line, and in the opposite directions from the center of the original image. And a sorting circuit 31 as sorting means for outputting two data strings output in parallel as one serial data string arranged in order from the data at the end of the original image by a circuit configuration as shown in FIG. It is provided. The description of the other circuit parts is omitted.

In the signal processing unit 14 of FIG. 13, the dark output memory 35 of ROM is used instead of the dark output memory 23 of the signal processing unit 14 of FIG. As a result, even in the case of this embodiment, FIG.
As in the case of 1, the operation of storing the dark output can be eliminated. Further, storage in the dark output memories 35a and 35b,
The adaptation conditions are the same as in the embodiment of FIG. Therefore, the signal processing unit 14 of FIG.
4 can be obtained, and the circuit configuration can be simplified because the dark output storage operation and the switching circuit are not required.

Next, an embodiment of the present invention will be described. In the present embodiment, the dark output is set even more accurately by setting the accumulation time when reading out the dark output signal over one line from the photoelectric conversion element longer than the accumulation time per line when reading an image. An object of the present invention is to provide an image reading device capable of performing correction.

That is, in each of the embodiments described so far, in each of the signal processing units 14 shown in FIGS. 1, 9 and 10,
By setting the accumulation time when reading out the dark output signal from the CCD line sensors 5a and 5b longer than the accumulation time per line when reading out an image, it is possible to take in advance 1
It is possible to increase the output level of the dark output signal of the line, thereby reducing deterioration during signal processing, and by storing the level as a dark output pattern, a more accurate dark output signal can be obtained. Output correction can be performed.

[0054]

According to the first aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversions for photoelectrically converting the formed reflected light. Element, a driving unit that drives these photoelectric conversion elements, and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, wherein the image reading apparatus is configured to block reflected light from sources other than the document. A light-shielding plate disposed in front of the photoelectric conversion element, and a document position corresponding to a pixel to be read first of the photoelectric conversion element is substantially at the center of the document area in the main scanning direction, and is read subsequently. and direction of the original position corresponding to the pixel opposite to each other to the output of the pixels of only the transfer portion without the exposed portion of the dark output signal over only a portion which is not shielded by the light shielding plate to read one line First holding means for holding the minute portion, second holding means for holding an output portion of a pixel having a light-shielded photosensitive portion, and one line based on the output values of the first and second holding means. Normalizing means for normalizing the dark output signal that passes therethrough, first memory means for storing the normalized dark output signal over one line, and storing the output of the pixel whose light-sensitive portion is light-shielded. A first dark output signal generating means for multiplying an output of the first storage means and an output of the second storage means to generate a dark output signal generated in each pixel; (1) a second dark output signal generator for generating a dark output signal actually output from the photoelectric conversion element based on an output of the dark output signal generator; The output when reading the image And a reordering unit that outputs two data strings output in parallel in opposite directions from the center of the document image as one serial data string arranged in order from the data at the end of the document image. Since it is provided in the signal processing means, high-speed and high-definition image reading becomes possible by using two photoelectric conversion elements and driving them independently and simultaneously. By reading out only the pixels involved in image reading while blocking light, it is possible to reduce the power consumption and the total data amount for driving the photoelectric conversion element depending on the size of the original. Further, the one-line dark output pattern obtained in advance is multiplied by the DS (S) value during image reading, and the dark output signal actually output from the photoelectric conversion element is generated using the result, and the photoelectric conversion signal is generated. Since the subtraction is performed from the image signal output from the conversion element, accurate dark-time output correction can be performed even when reading is performed for a smaller number of pixels than the number of pixels of the photoelectric conversion element. Further, since two data strings output in parallel in opposite directions from the center of the document image are output as one serial data string arranged in order from the edge of the document, the output format is one photoelectric conversion element. It can be the same as when used.

According to a second aspect of the present invention, there is provided an illumination light source for illuminating a document, image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. A light-shielding plate disposed in front of the element, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is substantially at the center of the document area in the main scanning direction, and is subsequently read. storage means for direction of the original position corresponding to the read pixel is opposite to each other, and stores the output signal when the dark over only a portion which is not shielded by the light shielding plate to read one line, Hikarishi the photosensitive unit Holding means for holding the output of the pixel which is being hidden, and multiplying the output of the holding means by the output of reading the contents of the storage means over one line to generate a dark output signal generated in each pixel. A first dark output generating means, a second dark output generating means for generating a dark output signal actually output from the photoelectric conversion element based on an output of the first dark output generating means, Second
Subtraction means for subtracting the output of the dark-time output generation means from the output when the image is read; and two data strings output in parallel in opposite directions from the center of the document image in order from the end data of the document image. Since the signal processing means and the rearrangement means for outputting as a serial data string are provided in the signal processing means, high-speed, high-definition image reading becomes possible by driving two photoelectric conversion elements independently and simultaneously. By using a light-shielding plate to shield reflected light from other than the original and reading only the pixels involved in image reading, it is possible to reduce the power consumption of the photoelectric conversion element drive and the total data amount depending on the original size. A memory for storing a dark output pattern is provided. The read output is multiplied by the DS (S) value during image reading, and the result is used to output the dark output actually output from the photoelectric conversion element. Since the signal is generated and subtracted from the image signal output from the photoelectric conversion element, accurate dark-time output correction can be performed even when reading is performed on a smaller number of pixels than the number of pixels of the photoelectric conversion element. Can be. Further, since two data strings output in parallel in the opposite direction from the center of the document image are output as one serial data string arranged in order from the edge of the document, the output format is one photoelectric conversion element. It can be the same as the case described above.

According to a third aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. A light-shielding plate disposed in front of the element, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is substantially at the center of the document area in the main scanning direction, and is subsequently read. hold means for direction of the original position corresponding to the read pixel is opposite to each other and holds the output of the pixel of the light shielding plate at not shading portions only transfer portion only without reading the photosensitive unit A peak hold means for holding a peak value of an output signal when reading a white reference plate over one line; a white reference plate read signal and an image over one line based on the output value of the hold means and the peak hold means; First normalizing means for normalizing the read signal; storage means for storing the normalized white reference plate read signal output from the first normalizing means over one line; A second normalizing means for normalizing the normalized image reading signal as an output by reading the contents of the storage means over one line and outputting the normalized image reading signal in parallel in opposite directions from the central portion of the original image; Two data strings are arranged in order from the data at the end of the original image.
And a rearrangement means for outputting as two serial data strings is provided in the signal processing means, so that a reference for quantization using the output of the dark output correction obtained by the image reading apparatus according to claim 1 or 2,
By creating a reference for shading correction and performing quantization and shading correction on the image reading signal subjected to the dark output correction, highly accurate quantization and shading correction can be performed.

According to a fourth aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising: driving means for driving these photoelectric conversion elements; and signal processing means for performing signal processing on output signals of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising: a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit. Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels that are subsequently read out are opposite to each other.
Only the portion that is not shaded by the light-shielding plate is read, the intensity of the illumination light source and the sub-scanning speed are controlled, and the output portion of the pixel only in the transfer portion without the photosensitive portion in the dark output signal over one line is held. First holding means, a second holding means for holding an output portion of a pixel having a light-shielded photosensitive portion, and a dark output over one line based on the output values of the first and second holding means. Normalization means for normalizing the signal, first storage means for storing a dark output signal over one line normalized by the normalization means, and storing the output of a pixel having a light-shielded photosensitive portion. A first dark output signal for generating a dark output signal generated in each pixel by multiplying an output of the second storage means and an output read over one line of the first storage means. Generation means A second dark output signal generating means for generating a dark output signal actually output from the photoelectric conversion element based on an output of the first dark output signal generating means; and a second dark output signal. Subtracting means for subtracting the output of the generating means from the output at the time of reading; and one serial line in which two data strings output in parallel in opposite directions from the center of the original image are arranged in order from the data at the end of the original image. Since the rearrangement means for outputting as a data string is provided in the signal processing means, the two photoelectric conversion elements are used and driven independently and simultaneously, and the pixels of the photoelectric conversion elements which do not contribute to reading due to the size of the original image are used. Since the light is shielded, the illumination light source is controlled, and the sub-scanning speed is controlled, high-speed and high-definition reading is possible, and high speed can be exhibited especially when reading a small-sized document. In addition, a one-line dark output pattern that has been fetched in advance is multiplied by the DS (S) value during image reading, and a dark output signal actually output from the photoelectric conversion element is generated using the result, and the photoelectric conversion signal is generated. Since the subtraction is performed from the image signal output from the conversion element, accurate dark-time output correction can be performed even when reading is performed on a smaller number of pixels than the number of pixels of the photoelectric conversion element. Further, since two data strings output in parallel in the opposite direction from the center of the document image are output as one serial data string arranged in order from the edge of the document, the output format is one photoelectric conversion element. It can be the same as the case described above.

According to a fifth aspect of the present invention, there is provided an illumination light source for illuminating a document, image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for performing photoelectric conversion of the formed reflected light. An image reading apparatus comprising a driving unit for driving these photoelectric conversion elements and a signal processing unit for performing signal processing on an output signal of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit; Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels to be subsequently read are opposite to each other.
A storage means for reading out only the portion not shielded by the light shielding plate, controlling the intensity of the illumination light source and the sub-scanning speed, and storing a dark output signal over one line, and a light shield for the photosensitive portion. Holding means for holding the output of a pixel; and a first dark output for generating a dark output signal generated at each pixel by multiplying the output of the holding means and the output of reading the contents of the storage means over one line. Signal generating means, second dark output signal generating means for generating a dark output signal actually output from the photoelectric conversion element based on the output of the first dark output signal generating means, and the second dark output signal generating means. Subtraction means for subtracting the output of the dark output signal generation means from the output when the image is read, and two data strings output in parallel in opposite directions from the center of the original image from the data at the end of the original image In order Since the rearranging means for outputting as one serial data string is provided in the signal processing means, two photoelectric conversion elements are used, which are driven independently and simultaneously, and which do not contribute to reading due to the size of the original image. By blocking the pixels of the element, controlling the illumination light source, and controlling the sub-scanning speed, high-speed and high-definition reading is possible, and high speed can be exhibited especially when reading a small-sized document. . Further, a memory for storing a dark output pattern is provided.
(S) is multiplied, the dark output signal actually output from the photoelectric conversion element is generated using the result, and subtraction is performed from the image signal output from the photoelectric conversion element. Even when reading is performed for only a small number of pixels, it is possible to perform accurate dark output correction.
Further, two data strings output in parallel in opposite directions from the center of the document image are arranged in order from the edge of the document.
Since the data is output as two serial data strings, the output format can be the same as that of one photoelectric conversion element.

According to a sixth aspect of the present invention, there is provided an illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, and two photoelectric conversion elements for photoelectrically converting the formed reflected light. An image reading apparatus comprising: driving means for driving these photoelectric conversion elements; and signal processing means for performing signal processing on output signals of the photoelectric conversion elements, wherein the photoelectric conversion is performed so as to block reflected light from sources other than the original. An original position corresponding to a read pixel read first of the photoelectric conversion element, comprising: a light-shielding plate disposed on the front surface of the element, an original size detection unit, an illumination light source control unit, and a sub-scanning speed control unit. Is substantially at the center of the document area in the main scanning direction, and the directions of the document positions corresponding to the read pixels to be subsequently read are opposite to each other.
A holding unit for reading out only the portion not shaded by the light shielding plate, controlling the intensity of the illumination light source and the sub-scanning speed, and holding the output of the pixel only in the transfer portion without the photosensitive portion, and a white reference for one line Peak holding means for holding a peak value of an output signal when reading a plate, and a white reference plate reading signal and an image reading signal over one line are normalized with reference to the output values of the holding means and the peak holding means. A first normalizing means, and a normalized white reference plate reading signal output from the first normalizing means
Storage means for storing the data over the lines, and second normalization means for normalizing the normalized image reading signal output from the first normalization means by the output of reading the contents of the storage means over one line. Reordering means for outputting two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image; Therefore, a reference for quantization and a reference for shading correction are created using the dark output correction output obtained by the image reading device according to claim 4 or 5, and the dark read output corrected image reading signal is generated. By performing quantization and shading correction on the other hand, highly accurate quantization and shading correction can be performed.

The invention according to claim 7 is the invention according to claims 1, 3, and 4.
Or, in the invention described in 6, the accumulation time when the dark output signal over one line is read out from the two photoelectric conversion elements,
Since the setting is made longer than the accumulation time per line at the time of image reading, it is possible to increase the output level of the dark output of one line to be taken in advance, thereby reducing deterioration during signal processing. In addition, by storing the level as a dark output pattern, it is possible to perform even more accurate dark output correction.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a state of a signal processing unit according to a first embodiment of the present invention.

FIG. 2 is a side view illustrating the overall configuration of the image reading apparatus.

FIG. 3 is a block diagram illustrating a configuration of a control unit of the image reading apparatus.

FIG. 4 is a timing chart showing various pulse waveforms output from a CCD driving unit.

FIG. 5 is an explanatory diagram showing a state in which dark outputs overlap when 60% of the pixels of the CCD line sensor are read out.

6A is a waveform diagram showing an output state of one line of a CCD line sensor, and FIG. 6B is a waveform diagram showing an output state of one line after removing a transfer clock waveform.

7A is a waveform diagram showing an output waveform for one line when the exposure amount of the CCD line sensor is set to zero, and FIG.
FIG. 4 is a waveform diagram showing a relationship between a reference of the A / D conversion circuit and a signal input, and FIG. 4C is a waveform diagram showing a relationship between two references of the A / D conversion circuit and a signal input.

8A and 8B are state diagrams showing a state of a data string before rearrangement, and FIG. 8C is a state diagram showing a state of a data line after rearrangement in a rearrangement circuit. , (D)
FIG. 3 is a state diagram showing a state of a data string converted and output by a select circuit after rearranging data.

FIG. 9 is a circuit diagram showing a signal processing unit according to a second embodiment of the present invention.

FIG. 10 is a circuit diagram showing a signal processing unit according to a third embodiment of the present invention.

FIG. 11 is a circuit diagram showing a state of a signal processing unit according to a first embodiment of the present invention.

FIG. 12 is a circuit diagram showing a signal processing unit according to a second embodiment of the present invention.

FIG. 13 is a circuit diagram showing a signal processing unit according to a third embodiment of the present invention.

[Explanation of symbols]

2 Document 3 Illumination light source 4a, 4b Imaging means 5a, 5b Photoelectric conversion element 6a, 6b Light shielding plate 10 Driving means 11 Document size detection means 12 Sub-scanning speed control means 13 Illumination light source control means 14 Signal processing means 16a, 16b First Hold means 17a, 17b Second hold means 21a, 21b Normalization means 23a, 23b First storage means 24a, 24b Second storage means 25a, 25b First dark output signal generation means 26a, 26b, 27a, 27b Second dark Time output signal generating means 28a, 28b subtracting means 32 rearranging means

Continuation of the front page (56) References JP-A-62-47274 (JP, A) JP-A-62-49782 (JP, A) JP-A-2-211771 (JP, A) JP-A-2-285772 (JP) , A) Japanese Patent Publication No. 1-53538 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1 / 04,1 / 401 G06T 1/00

Claims (7)

(57) [Claims] An illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from sources other than the document. comprising <br/> the placed light shielding plate Te, at approximately the center of the main scanning direction of the document position corresponding to the pixel to be read at the beginning of the photoelectric conversion element is the document area, and corresponds to the pixels read subsequently direction of the original position is opposite to each other, shielded with the light shielding plate
Driving means for driving the photoelectric conversion elements to read only have no portion being a first holding means for holding the output of the pixel of only the transfer portion without the exposed portion of the dark output signal over a single line, Second holding means for holding an output portion of a pixel having a light shield on the photosensitive portion; and a normalizing means for normalizing a dark output signal over one line based on the output values of the first and second holding means. First storage means for storing the normalized dark output signal over one line; second storage means for storing the output of a pixel having a light-shielded light-sensitive section; A first dark output signal generating means for multiplying an output of the storage means by an output of the second storage means to generate a dark output signal generated in each pixel; and an output of the first dark output signal generating means. Actually Second dark output signal generating means for generating a dark output signal output from the photoelectric conversion element; subtracting means for subtracting the output of the second dark output signal generating means from the output when the image is read; Reordering means for outputting two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image; An image reading device, comprising: 2. An illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements. In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from other than the original. comprising <br/> the placed light shielding plate Te, at approximately the center of the main scanning direction of the document position corresponding to the read pixel to be read at the beginning of the photoelectric conversion element is the document area, and reading are read followed by the pixel and opposite directions direction of the original position corresponding to the shielding
A storage means for reading out only a portion which is not shaded by the plate and storing a dark output signal over one line; a holding means for holding an output of a pixel having a light-shielded light-sensitive portion; an output of the holding means; First dark output generation means for multiplying the output of the storage means over one line by an output and generating a dark output signal generated at each pixel;
A second dark output signal which is actually output from the photoelectric conversion element based on the output of the first dark output generation means;
Dark output generating means, subtracting means for subtracting the output of the second dark output generating means from the output at the time of reading the image, and two parallel outputs in the opposite directions from the center of the original image.
An image reading device, wherein a rearrangement means for outputting two data strings as a serial data string arranged in order from the end data of the original image is provided in the signal processing means. 3. An illumination light source for illuminating a document, imaging means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements. In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from other than the original. comprising <br/> the placed light shielding plate Te, at approximately the center of the main scanning direction of the document position corresponding to the read pixel to be read at the beginning of the photoelectric conversion element is the document area, and reading are read followed by the pixel and opposite directions direction of the original position corresponding to the shielding
Driving means for driving the photoelectric conversion element so as to read only the portion not shielded by the plate, holding means for holding the output of the pixel only in the transfer portion without the photosensitive portion, and reading the white reference plate over one line Peak holding means for holding the peak value of the output signal at the time, and first normalizing means for normalizing the white reference plate reading signal and the image reading signal over one line with reference to the holding means and the output value of the peak holding means. Storage means for storing the normalized white reference plate reading signal output from the first normalizing means over one line; and a normalized image reading signal output from the first normalizing means. A second normalizing means for normalizing the contents of the storage means by an output read over one line, and two normalizing means which are output in parallel in opposite directions from the center of the original image Image reading apparatus characterized by a rearranging section provided in said signal processing means for outputting a data string as a single serial data ordered sequence from the data of the end of the document image. 4. An illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from sources other than the document. A light source plate, a document size detection means, an illumination light source control means, and a sub-scanning speed control means, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is mainly located in the document area. The directions of the document positions substantially at the center of the scanning direction and corresponding to the read pixels to be subsequently read are set to be opposite to each other, and are shielded by the light shielding plate depending on the size of the document.
A first holding means for reading out only the portion which has not been exposed, controlling the intensity of the illumination light source and the sub-scanning speed, and holding the output portion of the pixel only in the transfer portion without the photosensitive portion in the dark output signal over one line; Second holding means for holding an output portion of a pixel having a light-shielded light-sensitive portion, and a normalizing means for normalizing a dark output signal over one line based on the output values of the first and second holding means. Means for storing dark output signals over one line normalized by the normalizing means, and second memory means for storing outputs of pixels whose light-shielding is performed on the photosensitive section. A first dark output signal generating means for multiplying an output of the second storage means and an output read over one line of the first storage means to generate a dark output signal generated in each pixel; 1 Dark output A second dark output signal generating means for generating a dark output signal actually output from the photoelectric conversion element based on an output of the signal generating means, and an output of the second dark output signal generating means. Subtraction means for subtracting from the output of time, and rearrangement for outputting two data strings output in parallel in opposite directions from the center of the document image as one serial data string arranged in order from the data at the end of the document image. And an image reading device provided in the signal processing device. 5. An illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from other than the original. A light source plate, a document size detection means, an illumination light source control means, and a sub-scanning speed control means, and a document position corresponding to a read pixel to be read first of the photoelectric conversion element is mainly located in the document area. The directions of the document positions substantially at the center of the scanning direction and corresponding to the read pixels to be subsequently read are set to be opposite to each other, and are shielded by the light shielding plate depending on the size of the document.
Only the non- exposed portion is read, the intensity of the illumination light source and the sub-scanning speed are controlled, and the storage means for storing a dark output signal over one line and the output of the pixel which is light-shielded in the photosensitive portion are held. Holding means; first dark output signal generating means for multiplying the output of the holding means and the output of reading the contents of the storage means over one line to generate a dark output signal generated in each pixel; A second dark output signal generator for generating a dark output signal actually output from the photoelectric conversion element based on an output of the first dark output signal generator; and a second dark output signal generator. Subtraction means for subtracting the output of the original image from the output when the image is read, and one serial line in which two data strings output in parallel in opposite directions from the center of the original image are arranged in order from the data at the end of the original image. data Image reading apparatus characterized by a rearranging section that outputs provided in said signal processing means as. 6. An illumination light source for illuminating a document, an image forming means for forming an image of reflected light from the document, two photoelectric conversion elements for photoelectrically converting the formed reflected light, and these photoelectric conversion elements. In an image reading apparatus including a driving unit that drives and a signal processing unit that performs signal processing on an output signal of the photoelectric conversion element, the image reading apparatus is positioned on a front surface of the photoelectric conversion element so as to block reflected light from sources other than the document. A light source plate, a document size detection means, an illumination light source control means, and a sub-scanning speed control means, and a document position corresponding to a first read pixel of the photoelectric conversion element is located in a main area of the document area. The directions of the document positions substantially at the center of the scanning direction and corresponding to the read pixels to be subsequently read are set to be opposite to each other, and are shielded by the light shielding plate depending on the size of the document.
The read means only reads out the non-exposed portions, controls the intensity of the illumination light source and the sub-scanning speed, holds the output of the pixels only in the transfer portion without the photosensitive portion, and when reading the white reference plate over one line. A peak holding means for holding a peak value of an output signal; and a first means for normalizing a white reference plate reading signal and an image reading signal over one line with reference to the output values of the holding means and the peak holding means.
Normalization means, storage means for storing a normalized white reference plate read signal output from the first normalization means over one line, and a normalized image output from the first normalization means Second normalizing means for normalizing a read signal by an output of reading the contents of the storage means over one line;
Reordering means for outputting two data strings output in parallel in opposite directions from the center of the original image as one serial data string arranged in order from the data at the end of the original image; An image reading device, comprising: 7. The storage time when reading a dark output signal over one line from two photoelectric conversion elements is set longer than the storage time per line when reading an image. The image reading device according to claim 1, 3, 4, or 6.