JP2002185700A - Color image reader and color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a color image reader and a color image forming device capable of preventing the drop of signal outputs of lower sensitivity colors than other colors, and improving the S/N of the signal output, and preventing the deterioration of an input image. SOLUTION: This color image reader is provided with an image pickup means 17 constituted of a plurality of linear solid-state image pickup elements extended in a main scanning direction whose spectral sensitivities are different, an illuminating means 12a for illuminating an original to be read, and a driving means for allowing the image pickup means to read reflected lights from the original by moving at least either the image pickup means or the original to a sub-scanning direction. The illuminating means is provided with the difference of the light quantity of illumination in the sub-scanning direction within a range where simultaneous reading is operated by the plurality of linear solid-state image pickup elements of the image pickup means, and a linear solid-state image pickup element B whose sensitivity is the lowest of the image pickup means is arranged at a position where the light quantity with which the original is illuminated by the illuminating means is larger than that of the other linear solid-state image pickup elements RG.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading apparatus and a color image forming apparatus for handling color images, and more particularly, to a color image reading apparatus and a color image forming apparatus suitable for reading faithfully and with little deterioration.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view showing the arrangement of main components of a conventional color image reading apparatus as a sectional configuration. In FIG. 5, reference numeral 1 denotes a document to be read;
Reference numeral 11 denotes a document glass (platen glass) on which the document 1 is placed downward, 12a and 12b denote linear illumination means (lamp) having a sufficient length in a direction perpendicular to the paper surface (main scanning direction), 13 to 15 Is a mirror for guiding the reflected light from the document 1 to a sensor described later, 16 is a lens for condensing the reflected light from the document to a sensor described later, and 17 is a plurality of lines extending in the main scanning direction having different spectral sensitivities. An image sensor (imaging means) including a solid-state image sensor. In addition, in terms of the sensitivity of the image sensor 17 and the amount of light emitted from the lighting unit,
Two lamps of the illumination means 12a and 12b are used.

In this case, the image sensor 17 is
It has a (red) pixel column, a G (green) pixel column, and a B (blue) pixel column, and reads reflected light from an original in three colors of RGB as a color image. The illuminating means 12a and 12b and the mirrors 13 to 15 are driven in the left and right direction (sub-scanning direction) on the paper surface via motors and various belts (not shown), and the image sensor 17 reads reflected light from the original 1. It has a configuration. It is also possible to cause the image sensor 17 to read the original 1 by moving it.

In such a color image reading apparatus, the illuminating means 12a and 12b illuminate from both sides so as to sandwich the reading position of each color of RGB.
The light quantity distribution of each color of RGB is almost uniform.

[0005]

Conventionally, the amount of light of the original illuminating lamp as the illuminating means 12 was low and the light receiving sensitivity of the solid-state image sensor used for the image sensor 17 was low, so that two original illuminating lamps were used. I was using. As a result, the light amount distribution in the sub-scanning direction was flat, but the performance (sensitivity and S / N ratio) of the lamp and the solid-state imaging device was improved due to the recent improvement in technology, and as shown in FIG. Has become possible.

However, the integration of the illumination lamp results in different distances from the illumination lamp to the irradiation position of RGB. In this case, since the light amount decreases in inverse proportion to the square of the distance, a gradient (light amount difference) occurs in the light amount distribution in the sub-scanning direction. In the case of FIG. 6, the output of the blue (B) signal, which has lower sensitivity than the other colors, becomes lower, causing a problem such as a decrease in the SN ratio and deterioration of the input image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to prevent a decrease in signal output of a color having lower sensitivity than other colors and to improve an SN ratio of a signal output. It is an object of the present invention to realize a color image reading apparatus and a color image forming apparatus which can prevent deterioration of an input image.

The present invention has been made to solve the above-described problem, and it is intended to prevent a decrease in blue signal output having lower sensitivity than other colors and to improve the SN ratio of the blue signal output. It is an object of the present invention to realize a color image reading device and a color image forming device capable of preventing deterioration of an input image.

[0009]

That is, the present invention for solving the above problems is as described below. (1) The invention according to claim 1 is an image pickup means comprising a plurality of linear solid-state image pickup devices extending in the main scanning direction and having different spectral sensitivities, an illuminating means for illuminating a document to be read, and the image pickup means And a driving unit that causes at least one of the original and the original to move in the sub-scanning direction to cause the imaging unit to read the reflected light from the original. The plurality of linear solid-state imaging devices of the means have a difference in the amount of illumination in the sub-scanning direction within the range to be read simultaneously, and the least sensitive linear solid-state imaging device of the imaging device is connected to another line. A color image reading device, wherein the illumination unit is arranged at a position where the amount of light for illuminating the document is larger than that of the solid-state imaging device.

According to the present invention, when the illuminating means has a light amount difference of illumination in the sub-scanning direction within a range in which a plurality of linear solid-state imaging elements of the imaging means simultaneously read, the most sensitive of the imaging means. The linear solid-state imaging device having a lower brightness is arranged at a position where the amount of light to be illuminated is larger than that of the other linear solid-state imaging devices.

As a result, it is possible to prevent a decrease in signal output of a color having lower sensitivity than other colors, to improve an S / N ratio of a signal output, and to prevent a deterioration of an input image. A reading device can be realized.

(2) According to a second aspect of the present invention, there is provided an image pickup means comprising a plurality of linear solid-state image pickup devices having different spectral sensitivities including at least blue and extending in the main scanning direction and illuminating a document to be read. A color image reading apparatus comprising: an illuminating unit; and a driving unit configured to move at least one of the imaging unit and the document in a sub-scanning direction to cause the imaging unit to read the reflected light from the document. The illuminating means has a light amount difference of illumination in a sub-scanning direction within a range where a plurality of linear solid-state imaging elements of the imaging means simultaneously read, and the linear solid-state detecting means of the imaging means detects blue. A color image reading device, wherein an image sensor is arranged at a position where the amount of light for illuminating a document by the illumination unit is larger than that of another linear solid-state image sensor.

According to the present invention, when the illuminating means has a light amount difference of illumination in the sub-scanning direction within a range in which a plurality of linear solid-state imaging elements of the imaging means simultaneously read, a blue light source of the imaging means is used. Is arranged at a position where the amount of light to be illuminated is larger than that of the linear solid-state imaging devices of other colors.

As a result, it is possible to prevent a decrease in the output of the blue signal, which is lower in sensitivity than the other colors, to improve the SN ratio of the blue signal output, and to prevent the input image from deteriorating. An image reading device can be realized.

(3) According to a third aspect of the present invention, there is provided the color image reading device according to any one of the first and second aspects, wherein an image is formed based on the color image read by the color image reading device. And a color image forming apparatus.

According to the present invention, when the illuminating means has a light quantity difference of illumination in the sub-scanning direction within a range in which the plurality of linear solid-state imaging elements of the imaging means simultaneously read, the most sensitive of the imaging means. A color image reading device in which a linear solid-state imaging device having a low image density is arranged at a position where the amount of light to be illuminated is larger than other linear solid-state imaging devices is used for a color image forming apparatus.

As a result, it is possible to prevent a decrease in signal output of a color having lower sensitivity than other colors, to improve an SN ratio of a signal output, and to prevent deterioration of an input image, thereby forming a faithful image. Can be realized.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing an arrangement of main components of a color image reading apparatus according to an embodiment of the present invention as a sectional configuration. In this FIG.
Reference numeral 1 denotes a document to be read, 11 denotes a document glass (platen glass) on which the document 1 is placed downward, and 12a denotes a line-shaped illumination means (lamp) having a sufficient length in a direction perpendicular to the paper surface (main scanning direction). ), 13 to 15 are mirrors for guiding the reflected light from the document 1 to a sensor described later, 16 is a lens for condensing the reflected light from the document to a sensor described later, 1
Reference numeral 7 denotes an image sensor (imaging unit) including a plurality of linear solid-state imaging devices extending in the main scanning direction and having different spectral sensitivities.
It is.

The illuminating means 12a and the mirrors 13 to 15 are driven in the horizontal direction (sub-scanning direction) of the paper surface via motors and various belts (not shown), and the reflected light from the original 1 is read by the image sensor 17. It is configured to make it. It is also possible to cause the image sensor 17 to read the original 1 by moving it.

In this embodiment, the image sensor 1
7 in terms of the sensitivity of the illumination unit 7 and the amount of light emitted by the illumination unit.
Only one lamp a is used. Here, by integrating the lighting lamp, the RG
Since the distance to the irradiation position B becomes different, and the light amount decreases in inverse proportion to the square of the distance, the light amount distribution in the sub-scanning direction has a slope (light amount difference). In this case, the light amount difference is inclined, but a light amount difference that is not inclined may occur depending on the light distribution pattern of the illumination lamp.

In this case, the image sensor 17 is
As shown in FIG. 2, the linear solid-state imaging devices (R
(Red) pixel row, G (green) pixel row, and B (blue) pixel row) at intervals of ΔL in the sub-scanning direction.
The reflected light from the original is read as a color image in three colors.

For this reason, the positions where red, green and blue images are taken on the document surface are separated by nΔL as shown in FIG. 3 where the reflection of the mirror is omitted, and as a whole (2n
ΔL) exists. Here, n means the reciprocal of the reduction magnification of the lens 16 used in the imaging system. That is, in the image sensor 17, even if the distance between the line-shaped solid-state imaging devices is minute, ΔL is multiplied by the reciprocal of the reduction magnification at the reading position.

In such a case, when two conventional document illumination lamps shown in FIG. 5 are present, the light amount distribution on the document surface is large even if it is separated from the red to blue imaging position difference (2n △ L). There was no change in light intensity.

However, in the case of an apparatus in which the number of original illumination lamps is reduced to one, the light amount distribution on the original surface has an inclination in the sub-scanning direction as shown in FIG. 1 or FIG. This is because the light amount of the document illumination lamp becomes darker in proportion to the square of the distance, so that the light amount on the document surface decreases as the distance from the lamp increases (as the lamp does not exist). The amount of light received by each color pixel at this time is as shown in FIG.
It can be seen that there is a great difference between the three colors (green) and B (blue).

Now, the three-line color image sensor 17
Are generally in the order of [blue <red <green]. In this case, if the arrangement in which the amount of received light of B (blue) is smaller than that of the other colors as shown in FIG. It is evident that the output signal level decreases and the SN ratio becomes lower than that of the other colors, resulting in deterioration of the input image.

Therefore, in this embodiment, in order to improve this, as shown in FIG.
(Blue) The pixels are arranged so that the amount of light received by the pixel column is larger than that of other colors. In FIG. 1, since the arrangement of the image sensor 17 is the same as that of the conventional FIG. 6, the illuminating means is arranged on the opposite side to FIG.

If the illuminating means is located on the same side as that of FIG. 6, as shown in FIG.
A similar effect can be obtained by reversing the arrangement of the GB solid-state imaging devices.

Here, B (blue) is replaced with another color (R
(Red) and G (green)), the description is based on the premise that the light receiving sensitivity is lower than that of the color of the three-line color image sensor used in the original surface. Obviously, it is sufficient to increase the amount of light. The same applies to a case where two or four or more colors of imaging means are used, or a case where complementary color system imaging means other than RGB is used.

As described above, in this embodiment, when the illuminating means has a light quantity difference of illumination in the sub-scanning direction within a range where a plurality of linear solid-state image sensors of the imaging means simultaneously read. In addition, as a result of arranging the least sensitive linear solid-state imaging device of the imaging means at a position where the amount of light to be illuminated is larger than other linear solid-state imaging devices, the sensitivity is higher than that of other colors. It is possible to realize a color image reading apparatus that can prevent a decrease in signal output of a low color, improve an SN ratio of a signal output, and prevent deterioration of an input image.

By using the color image reading apparatus (color scanner) configured as described above in various color image forming apparatuses such as a color copying machine and a color facsimile apparatus, the sensitivity is lower than other colors. A color image forming apparatus capable of preventing a decrease in color signal output and improving an S / N ratio of a signal output, and capable of forming a faithful image by preventing deterioration of an input image is realized. be able to.

[0031]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, when the illuminating device has a light amount difference of illumination in the sub-scanning direction within a range where a plurality of linear imaging devices of the imaging device read simultaneously, Is arranged at a position where the amount of light to be illuminated is larger than that of other linear imaging means, so that the signal output of a color having lower sensitivity than other colors is reduced. In addition, it is possible to improve the signal-to-noise ratio of the signal output and to realize a color image reading apparatus capable of preventing deterioration of the input image.

(2) According to the second aspect of the present invention, when the illuminating means has a light amount difference of illumination in the sub-scanning direction within a range where a plurality of linear imaging means of the imaging means read simultaneously, Among the means, the linear solid-state imaging device for blue is arranged at a position where the amount of light to be illuminated is larger than that of the linear imaging means of other colors, so that the blue color solid-state imaging device having lower sensitivity than the other colors is used. It is possible to realize a color image reading apparatus capable of preventing a decrease in signal output and improving an SN ratio of a blue signal output, and capable of preventing deterioration of an input image.

(3) According to the third aspect of the present invention, when the illuminating means has a light amount difference of illumination in the sub-scanning direction within a range where a plurality of linear imaging means of the imaging means simultaneously read, the imaging is performed. A color image reading device in which the least-sensitive linear solid-state imaging device of the means is arranged at a position where the amount of light to be illuminated is larger than other linear imaging devices is used for a color image forming apparatus. As a result, it is possible to prevent a decrease in signal output of a color having lower sensitivity than other colors, and to improve the SN ratio of the signal output.
A color image forming apparatus capable of faithfully forming an image by preventing deterioration of an input image can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a color image reading device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a configuration of a main part of the color image reading device according to the embodiment of the present invention;

FIG. 3 is a configuration diagram illustrating a state of a main part of the color image reading device according to the embodiment of the present invention;

FIG. 4 is an explanatory diagram illustrating another example of the configuration of the color image reading device according to the embodiment of the present invention;

FIG. 5 is an explanatory diagram showing a configuration of a conventional color image reading device.

FIG. 6 is an explanatory diagram showing another example of the configuration of the conventional color image reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original 10 Scanner (color image reading apparatus) 11 Original glass 12a, 12b Illumination means 13-15 Mirror 16 Lens 17 Image sensor

Continued on the front page F term (reference) 5B047 AA01 AB04 BB03 BC01 BC05 BC09 BC12 BC23 5C051 AA01 BA03 DA03 DB01 DB22 DB24 DB28 DC02 DC05 DC07 EA01 FA01 5C072 AA01 BA11 CA03 CA04 DA02 DA04 EA05 FA08 QA10 XA01

Claims (3)

[Claims] An imaging unit comprising a plurality of linear solid-state imaging devices extending in a main scanning direction and having different spectral sensitivities; an illumination unit for illuminating a document to be read; and at least one of the imaging unit and the document. A driving unit for causing the imaging unit to read the reflected light from the original by moving one of the imaging units in the sub-scanning direction, wherein the illumination unit includes a plurality of lines of the imaging unit. The solid-state image sensor has a light amount difference of illumination in the sub-scanning direction within a range where the solid-state image sensor simultaneously reads, and the line-shaped solid-state image sensor having the lowest sensitivity among the image-capturing means is compared with other line-shaped solid-state image sensors. A color image reading device, wherein the illuminating means is arranged at a position where the amount of light for illuminating the document is large. 2. An image pickup means comprising a plurality of linear solid-state image pickup elements having different spectral sensitivities including at least blue and extending in a main scanning direction, illuminating means for illuminating a document to be read, A driving unit for causing the imaging unit to read the reflected light from the original by moving at least one of the original and the original in the sub-scanning direction. The linear solid-state imaging device has a light amount difference of illumination in the sub-scanning direction within a range where a plurality of linear solid-state imaging devices read at the same time. A color image reading apparatus, wherein the light source is arranged at a position where the amount of light for illuminating a document is larger than that of an image sensor. 3. A color image, comprising: the color image reading device according to claim 1; and forming an image based on the color image read by the color image reading device. Forming equipment.