JP2000125075A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower cost and save space without deterioration of an image pickup element and read picture quality due to infrared light, etc., even when a light source emitting light including the infrared light is used. SOLUTION: An original 12 is arranged on contact glass 11 and a lighting optical system having a light source arranged below the contact glass 11 irradiates the original 12. The illumination light reflected by the original 12 after being reflected and deflected by a 1st mirror 13-a of a 1st travel body 13 is reflected and deflected by a 1st mirror 14-a and a 2nd mirror 14-b of a 2nd travel body 14 in order, led to an image forming lens 15, and imaged on the incidence surface of a line sensor 16 by the image forming lens 15. In front of the package of the line sensor 16, cover glass 17 composed of a color glass filter having a prescribed spectral characteristics transmitting only green light, etc., is arranged instead of cover glass which is usually provided in front of the package of the line sensor 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus used in a document reading apparatus used in a copying machine, a facsimile, and the like.

[0002]

2. Description of the Related Art In copiers and facsimile machines,
2. Description of the Related Art As a document reading optical system for reading a document image, an image reading apparatus using a reduced reading optical system that reduces and forms reflected light of a document illuminated by an illumination system on a line sensor by an imaging lens is known. An image reading apparatus using a conventional reduced reading optical system is configured as shown in FIG. In FIG. 4, an original 2 is placed on a contact glass 1, and the original 2 is provided by an illumination optical system (not shown) having a light source arranged below the contact glass 1.
Is illuminated.

The illuminating light reflected by the original 2 is reflected and deflected by the first mirror 3-a of the first traveling body 3 and then reflected by the second mirror 3a.
First mirror 4-a and second mirror 4-b of the traveling body 4
Are sequentially reflected and deflected, and are guided to the imaging lens 5, where the image is reduced and formed on the incident surface of the line sensor 6 by the imaging lens 5. A cover glass 7 is arranged on the front surface of the package of the line sensor 6. At the time of reading, in the longitudinal direction of the document 2, the first traveling body 3 moves at the speed V to the position 3 '.
And at the same time, in conjunction with it, the second traveling body 4
At half speed of the first traveling body 3, that is, 1/2 V, it moves to the position 4 ′, and reads the entire length of the original 2.

As a light source of an illumination optical system used in the above-described reduction reading optical system, a fluorescent lamp or a halogen lamp is used. Among them, fluorescent lamps have the advantages of lower power consumption and less temperature rise than halogen lamps, but the absolute light quantity is one of that of halogen lamps.
It is as small as about / 10. Therefore, in order to read a document at high speed, it is necessary to use a halogen lamp having a large absolute light amount. On the other hand, as a line sensor used in an image reading apparatus for reading a document, a CCD (Charge C
oupled Device: A line sensor is used. CCDs have high sensitivity in the infrared region. If a halogen lamp is used as the light source,
And its light receiving characteristics are degraded. For this reason, generally, when a halogen lamp is used, a filter for cutting infrared light is arranged in the optical system.

[0005]

The above-described filter for cutting infrared light can be arranged at any position between the original surface and the light receiving surface of the CCD line sensor. The closer it is, the greater the effect of the filter surface accuracy on the imaging performance. Here, the arrangement of a conventional filter will be described for some examples together with its problems. The filter 8-a shown in FIG. 4 is an arrangement example when the filter 8-a is arranged and mounted on the object side of the imaging lens 5.
In this case, a filter 8-b described later is not provided. When the filter 8-a is arranged on the object side of the imaging lens 5,
Generally, the shape of the filter 8-a is rectangular. Also,
Although not shown, in this case, a member for fixing the filter 8-a is separately required.

As described above, when the shape of the filter 8-a is not circular, it becomes difficult to machine the surface with high precision, and further, mounting parts for fixing the filter 8-a are required. Costs rise significantly. In order to reduce the influence of the surface accuracy of the filter 8-a, it is effective to move the filter 8-a away from the imaging lens 5. However, if the filter 8-a is moved as far as possible from the imaging lens 5, the area of the filter 8-a itself becomes large, and the cost of the filter 8-a itself becomes high. Moreover, the object side of the imaging lens 5 is
Move to the position 4 ', it is necessary to secure a space so that the filter 8-a does not collide with the second traveling body 4.
Cannot be placed away from the object side.

The filter 8-b shown in FIG. 4 is an example in which the filter 8-b is arranged on the image side of the imaging lens 5, and in this case, the above-described filter 8-a is not provided. That is, in FIG. 4, one of the filters 8-a and 8-b is selectively disposed. Thus, even when the filter 8-b is arranged on the image side of the imaging lens 5, the filter 8-b has a rectangular shape and is not circular as in the case where the filter 8-b is arranged on the object side. Cannot be obtained, and furthermore, a part for mounting the filter 8-b is required, resulting in a significant increase in cost.

FIG. 5 shows an example in which a circular filter 8-c is attached to a mirror frame 5-a of the imaging lens 5, and FIG. 6 shows an example in which a filter 8-d is disposed in the imaging lens 5. It is. 5 and FIG. 6, the filter 8-c
And 8-d are located inside or very close to the imaging lens 5. Therefore, the filters 8-c and 8-d require the same surface accuracy as the imaging lens 5, and the costs of the filters 8-c and 8-d themselves increase. Further, as described above, the filter 8-is disposed on the image side of the imaging lens 5 and inside the imaging lens 5.
When c and 8-d are arranged, large astigmatism occurs due to the filters 8-c and 8-d and the like.
The lens of the imaging lens 5 must be designed so as to cancel astigmatism due to the filters 8-c and 8-d and the like by the lens design.

In this case, even if the filters 8-c and 8-d are not required, the filters 8-c
And 8-d etc. as well as filter 8-
Instead of c and 8-d, glass having the same refractive index and the same thickness as those must be inserted and arranged. Also,
Filter 8 to achieve low cost and space saving
Instead of -a to 8-d or the like, there is also a technique of forming a vapor deposition film having an infrared cut characteristic on the lens surface of the imaging lens 5 by vapor deposition and coating the film. Therefore, it is not suitable for a high-precision image reading optical system in an image reading apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and even if a light source including infrared light or the like is used, there is no deterioration of an image pickup device or reading image quality due to infrared light or the like, and low cost and space saving. It is an object of the present invention to provide an image reading apparatus that realizes the above-described method and does not require the use of a special imaging lens. In particular, it is an object of the present invention to provide an image reading apparatus capable of effectively preventing a failure when a light source that generates light including unnecessary light is used. In particular, an object of claim 2 of the present invention is to provide an image pickup device and an image reading apparatus that can effectively prevent deterioration of read image quality when a light source that generates light including infrared light is used. In particular, it is an object of the present invention to provide an image reading apparatus which is effective for reading a color original. In particular, it is an object of the present invention to provide an image reading apparatus that is effective for reading a color original and that can effectively use the light of a light source.

[0011]

According to a first aspect of the present invention, there is provided an image reading apparatus, comprising: an illumination system for illuminating an original; and an illumination system for illuminating the original illuminated by the illumination system. An image reading optical system having an image forming lens for reducing and forming an image of the reflected light and a line sensor for photoelectrically converting a document image formed by the image forming lens, wherein the line sensor transmits a predetermined wavelength region. And a cover glass having the following characteristics. An image reading apparatus according to the present invention is characterized in that the cover glass of the line sensor has a characteristic of blocking a wavelength in an infrared region.

According to a third aspect of the present invention, in the image reading apparatus, the line sensor is a three-line sensor. In the image reading apparatus according to the present invention described in claim 4, the cover glass of the line sensor includes:
The color glass filter is characterized in that it is a color glass filter having a characteristic of blocking a light beam in an infrared region only in a portion through which a light beam incident on a line sensor for reading red information passes.

[0013]

That is, in the image reading apparatus according to the first aspect of the present invention, the reflected light of the document illuminated by the illumination system is reduced and formed by the image forming lens, and the formed document image is photoelectrically converted by the line sensor. An image reading optical system, wherein the line sensor includes:
It has a cover glass having a property of transmitting a predetermined wavelength range. In this way, the cover glass of a line sensor such as a CCD is configured as a filter having a characteristic of transmitting an arbitrary wavelength, so that infrared light is included to increase the amount of light without adding a new filter and a mounting member. Even if the light source is changed, the common use of an imaging lens
The line sensor such as D does not deteriorate due to infrared light, realizes low cost, space saving, and at high speed, monochrome (monochrome: so-called monochrome. Hereinafter, “monochrome”)
). In addition, since the cover glass itself provided in a line sensor such as a CCD is changed to a filter in a normal case, the performance does not fluctuate even when a normally designed imaging lens is used. Can be obtained.

In the image reading apparatus according to a second aspect of the present invention, the cover glass of the line sensor is a filter having a characteristic of blocking a wavelength in an infrared region. In this manner, the configuration in which the cover glass of a line sensor such as a CCD is used as an infrared cut filter can effectively use the light amount of a light source including infrared light without adding a new filter and a mounting member. In addition, a line sensor such as a CCD is not deteriorated by infrared light, low cost, space saving is realized, and an original can be read in monochrome at a very high speed.

According to a third aspect of the present invention, there is provided an image reading apparatus.
The line sensor is a three-line sensor. As described above, the configuration in which the cover glass of the three-line sensor such as a three-line CCD is used as an infrared cut filter prevents deterioration of the line sensor such as a CCD due to infrared light without adding a new filter and a mounting member. And at low cost,
It saves space and can read documents in full color at high speed. The image reading device according to claim 4, wherein the cover glass of the line sensor has a characteristic of blocking light in an infrared region only in a portion where a light beam incident on the line sensor for reading red information passes. Filter. As described above, the portion through which the red light beam passes in the cover glass of the three-line sensor such as the three-line CCD is partially used as the infrared cut filter, so that the CCD and the like can be mounted without adding a new filter and a mounting member. This prevents the line sensor from deteriorating due to infrared light, realizes low cost and space saving, and can read a document in full color at very high speed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image reading apparatus according to the present invention will be described in detail based on embodiments with reference to the drawings. FIG. 1 shows a configuration of a main part of an image reading apparatus according to a first embodiment of the present invention. FIG. 1 schematically shows an arrangement configuration of a document reading optical system in an image reading apparatus as viewed from the front. FIG. 1 shows a contact glass 11, a document 12, a first traveling body 13, a second traveling body 14, an imaging lens 15, a line sensor 16, and a cover glass 17, and further includes a first traveling body. 13 first mirror 13
-A, a first mirror 14-a of the second traveling body 14 and a second mirror 14-b of the second traveling body 14 are also shown.

The contact glass 1 shown in FIG.
1, a document 12, a first traveling body 13, a second traveling body 14,
Imaging lens 15, line sensor 16, first traveling body 13
, The first mirror 14-a of the second traveling body 14 and the second mirror 14-of the second traveling body 14.
b is the contact glass 1, the original 2, the first glass shown in FIG.
, The second traveling body 4, the imaging lens 5, the line sensor 6, the first mirror 3-a of the first traveling body 3, the first mirror 4-a of the second traveling body 4, and the like. This is almost the same as the second mirror 4-b of the second traveling body 4. In an image reading apparatus that reads the document 12 in monochrome (monochrome: single color), a green fluorescent lamp is generally used as a light source when the reading speed is relatively slow. However,
In recent years, in this type of image reading apparatus, high-speed reading has been demanded. When the reading speed increases, it becomes necessary to use a halogen lamp having a large amount of light as a light source.
At this time, if the lens constituting the reading optical system at high speed is to be used in common with the case at low speed, unless the wavelength range of the illumination light is substantially the same as that of the green fluorescent lamp even when the halogen lamp is used, the lens will not be used. The imaging performance is greatly deteriorated.

Therefore, in the image reading apparatus shown in FIG. 1 having substantially the same configuration as that of a conventionally used image reading apparatus, the cover glass 17 disposed in front of the package of the line sensor 16 is provided with a predetermined spectral characteristic, For example, it is constituted by a color glass filter having a spectral characteristic of removing unnecessary light and transmitting only green light. By doing so, a large amount of light can be obtained as compared with the case where a green fluorescent lamp is used, and harmful infrared light to the CCD constituting the line sensor 16 can be cut. In addition, it is possible to configure an image reading apparatus for high-speed reading by using the imaging lens 15 and the like in common without adding a separate filter (corresponding to claim 1).

That is, in FIG. 1, a document 12 is placed on a contact glass 11 and the contact glass 1
The original 12 is illuminated by an illumination optical system (not shown) having a light source that moves in the main scanning direction together with the first traveling body 13 and is disposed below the first traveling body 13. The illumination light reflected by the document 12 is transmitted to the first mirror 13-of the first traveling body 13.
After being reflected and deflected by a, the light is sequentially reflected and deflected by the first mirror 14-a and the second mirror 14-b of the second traveling body 14, and is guided to the image forming lens 15, and the line is formed by the image forming lens 15. An image is formed on the incident surface of the sensor 16. As described above, on the front surface of the package of the line sensor 16, for example, the cover glass 1 made of a color glass filter having a predetermined spectral characteristic such as a spectral characteristic that transmits only green light.
7 is arranged. The cover glass 17 made of a color glass filter having a predetermined spectral characteristic is provided instead of the cover glass normally provided on the front surface of the package of the conventional line sensor.

When reading the original 12, in the longitudinal direction of the original 12, the first traveling body 13
3 'and at the same time in conjunction therewith the second traveling body 1
4 is half the speed of the first traveling body 13, that is, 1/2
At V, the document 12 is moved to a position 14 ', and the entire length of the document 12 (main scanning direction) is read. As described above, since the cover glass 17 of the line sensor 16 such as a CCD is a filter having a characteristic of transmitting a predetermined wavelength, it is necessary to add a new filter and a mounting member, etc. Even if the light source is changed to a light source including external light, a reading optical system such as the imaging lens 15 can be used in common,
There is no deterioration of the line sensor 16 such as a CCD due to infrared light, low cost and space saving are realized, and high-speed monochrome reading can be performed.

In the configuration shown in FIG. 1, it is assumed that a lens whose color has been corrected in a wide wavelength range is used as the imaging lens 15 and the like of the reading optical system. As described above, when the color correction region of the lens is wide, even if the light emission intensity distribution of the light source slightly changes, the fluctuation of the imaging performance is small. In such a case, if only the infrared region of the light of the light source is cut, the light amount of the light source can be used most effectively. Therefore, the cover glass 17 disposed in front of the package of the line sensor 16 in FIG. 1 is used as an infrared cut filter. With this configuration, it is possible to configure an image reading apparatus capable of reading a document in monochrome at a very high speed (corresponding to claim 2).

As described above, the line sensor 16 such as a CCD
Since the cover glass 17 is an infrared cut filter,
Without adding new filters and mounting components
The light amount of the light source including the infrared light can be effectively used, the line sensor 16 such as the CCD is not deteriorated by the infrared light, the cost and space can be reduced, and the monochrome sensor can be very fast. Reading can be performed.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a configuration of a main part of an image reading apparatus according to a second embodiment of the present invention. FIG. 2 schematically shows an arrangement configuration of the document reading optical system in the image reading apparatus as viewed from the front. FIG. 2 shows a contact glass 21, a document 22, a first traveling body 23, and a second traveling body 2.
4, an imaging lens 25, a line sensor 26, and a cover glass 27 are shown, and a first mirror 23-a of a first traveling body 23 and a first mirror 24 of a second traveling body 24 are shown.
-A and a second mirror 24-b of the second traveling body 24 are also shown.

The contact glass 2 shown in FIG.
1, a document 22, a first traveling body 23, a second traveling body 24,
Imaging lens 25, cover glass 27, first traveling body 23
, The first mirror 24-a of the second traveling body 24 and the second mirror 24-of the second traveling body 24.
b denotes the contact glass 11, the original 12, and the original 12 shown in FIG.
First traveling body 13, second traveling body 14, imaging lens 1
5, the cover glass 17, the first mirror 13-a of the first traveling body 13, the first mirror 14-a of the second traveling body 14, and the second mirror 14-b of the second traveling body 14. Equivalent to. In this case, only the line sensor 26 is greatly different from the case of FIG. 1, and is a three-line sensor including a three-line CCD corresponding to the three primary colors.

In recent years, in an image reading apparatus capable of reading a document in full color, many optical systems using a line sensor 26 composed of three line sensors are used as shown in FIG. The line sensor 26, which is a three-line sensor, includes three unit line sensors 26 per chip.
-A, 26-b and 26-c are arranged in the sub-scanning direction, and for color separation, for example, R (red), G (green)
And B (blue) filters are provided on-chip. This type of three-line sensor is a three-line CCD
Are often used. An optical system using a three-line CCD can perform color separation in a CCD line sensor, so that a mechanism such as a rotary filter for color separation is not required, and full-color information can be read by one scan. Therefore, full-color reading can be performed at a low cost, in a compact size, and at a high speed.

When a line sensor 26 comprising a three-line sensor such as the three-line CCD described above is used, the cover glass 27 on the front surface of the package of the three-line line sensor 26 shown in FIG. , Infrared rays harmful to a line sensor such as a CCD can be cut off, and high-speed full-color reading can be performed without separately adding a new mounting member and a filter. Corresponding). That is,
In FIG. 2, a document 22 is placed on a contact glass 21, and the document 22 is illuminated by an illumination optical system (not shown) having a light source placed below the contact glass 21.

The illumination light reflected by the original 22 is reflected and deflected by the first mirror 23-a of the first traveling body 23, and then is reflected by the first mirror 24-a of the second traveling body 24 and the second mirror 23-a.
The light is sequentially reflected and deflected by the mirror 24-b, and is formed into an imaging lens 25.
To the line sensor 26 by the imaging lens 25.
Is imaged on the incident surface of. As described above, the line sensor 26 includes three unit line sensors 26-a and 26-a.
A cover glass 27 made of a color glass filter having predetermined spectral characteristics such as a spectral characteristic for cutting infrared light is disposed on the front surface of the package of the line sensor 26.

When reading the original 22, in the longitudinal direction of the original 22, the first traveling body 23 and the illumination optical system move to the position 23 'at a speed V, and at the same time, the second traveling body 24 moves in conjunction therewith. , Half the speed of the first traveling body 23,
That is, at 1 / 2V, the document 2 is moved to the position 24 'and the original 2
2 is read in the entire longitudinal direction. Thus, three lines C
Since the cover glass 27 of the three-line sensor 26 made of a CD or the like is used as an infrared cut filter, infrared light from a CCD line sensor or the like constituting the line sensor 26 can be used without adding a new filter and a mounting member. Without deterioration, low cost and space saving,
In addition, full-color reading can be performed at high speed.

Incidentally, the halogen lamp is, for example, 40
Since the amount of light gradually increases from the short wavelength side near 0 nm to the long wavelength side, the blue side generally has a shortage of light amount as compared with the red side. Therefore, in the third embodiment of the present invention, the configuration is as shown in FIG. FIGS. 3A and 3B show the configuration of the cover glass 37 and the line sensor 36, which are main parts. FIG. 3A is a front view of the cover glass 37, and FIG. It is a side view of a part. For example, unit C
Only the portion of the cover glass 37 of the three-line CCD 36 composed of the CD line sensors 36-a, 36-b and 36-c, through which the light beam imaged on the red unit CCD line sensor 36-a passes, is subjected to infrared cut characteristics. Is formed as an infrared cut filter unit 37-a, and the light amount of green and blue light with a small light amount of the light source is passed through the normal glass unit 37-b, so that the entire surface of the cover glass 37 is an infrared cut filter. It is possible to increase the amounts of green and blue light more than at the time, and to correspond to faster full-color reading (corresponding to claim 4).

As described above, the portion through which the red light beam of the cover glass 37 of the three-line CCD 36 passes is the infrared cut filter portion 37-a, so that the CCD line sensor can be provided without adding a new filter and a mounting member. This realizes low cost and space saving without deterioration due to infrared light, and can perform full-color reading at a very high speed. Further, in each of the above-described embodiments, since the cover glass normally provided in the line sensor such as the CCD is changed to the filter, there is no change in the performance even when a normally designed lens is used. And sufficiently good performance can be obtained.

[0031]

As described above, according to the present invention, the reflected light of the document illuminated by the illumination system is reduced and formed by the image forming lens, and the formed document image is photoelectrically converted by the line sensor. An image reading optical system, wherein the line sensor has a cover glass having a property of transmitting a predetermined wavelength range;
By changing the cover glass of a line sensor such as a CD to a filter having the property of transmitting an arbitrary wavelength, it can be changed to a light source containing infrared light to increase the amount of light without adding a new filter and mounting member. Even if the imaging lens is used in common, there is no deterioration of the image sensor and reading image quality due to infrared light, etc., realizing low cost and space saving, and it is not necessary to use a special imaging lens. In particular, it is possible to provide an image reading apparatus that can effectively prevent a failure when a light source that generates light including unnecessary light is used.

Further, according to the image reading apparatus of the second aspect of the present invention, the cover glass of the line sensor such as the CCD is configured as an infrared cut filter, so that a red filter can be provided without adding a new filter and a mounting member. The light amount of the light source including the external light can be used effectively, the line sensor such as CCD is not deteriorated by the infrared light, the cost is reduced, the space is saved, and the document is read in monochrome at a very high speed. be able to. Furthermore, according to the image reading apparatus of the third aspect of the present invention, the cover glass of the three-line sensor such as the three-line CCD is configured as an infrared cut filter, so that a new filter and a mounting member are not added. A line sensor such as a CCD can be prevented from deteriorating due to infrared light, low cost, space saving can be realized, and an original can be read in full color at high speed.

According to the image reading apparatus of the fourth aspect of the present invention, the cover glass of the line sensor is used to emit light in the infrared region only at the portion where the light beam incident on the line sensor for reading red information passes. As a cutoff characteristic, a portion through which a red light beam passes in a cover glass of a three-line sensor such as a three-line CCD is partially set as an infrared cut filter, so that a new filter and a mounting member are not added. Thus, it is possible to prevent the line sensor from deteriorating due to infrared light, realize low cost, save space, and read a document in full color at very high speed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of a main part of an image reading apparatus according to a first embodiment of the present invention.

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

FIG. 3 is a diagram schematically illustrating front and side configurations of a line sensor and a cover glass, which are main components of an image reading apparatus according to a third embodiment of the present invention.

FIG. 4 is a diagram schematically showing a configuration of a main part and an arrangement of filters of an example of a conventional image reading apparatus.

FIG. 5 is a diagram schematically showing an arrangement configuration of a filter of an imaging lens unit which is a main part of another example of the conventional image reading apparatus.

FIG. 6 is a diagram schematically illustrating an arrangement configuration of a filter of an imaging lens unit which is a main part of another example of the conventional image reading apparatus.

[Explanation of symbols]

 11, 21 Contact glass 12, 22 Document 13, 23 First traveling body 14, 24 Second traveling body 15, 25 Imaging lens 16, 26, 36 Line sensor 17, 27, 37 Cover glass 13-a, 23 -A First mirror 14-a, 24-a of first traveling body First mirror 14-b, 24-b of second traveling body Second mirror 26-a, 26-b of second traveling body , 26-c unit line sensor 36-a, 36-b, 36-c unit line sensor 37-a infrared cut filter unit 37-b normal glass unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H048 CA06 CA12 CA17 CA22 CA24 4G062 AA04 BB01 MM02 MM21 NN05 NN12 4M118 AA10 AB10 BA10 FA06 FA08 GA03 GC08 GC11 HA02 5C051 AA01 BA03 DA06 DB22 DB23 DB28 DC04 EA01

Claims (4)

[Claims] An illumination system for illuminating the original; an imaging lens for reducing and forming an image of the reflected light of the original illuminated by the illumination system; and a line for photoelectrically converting the original image formed by the imaging lens. An image reading apparatus, comprising: an image reading optical system having a sensor; and the line sensor includes a cover glass having a characteristic of transmitting a predetermined wavelength range. 2. The image reading apparatus according to claim 1, wherein the cover glass of the line sensor has a characteristic of blocking a wavelength in an infrared region. 3. The image reading device according to claim 1, wherein the line sensor is a three-line sensor. 4. The cover glass of the line sensor is a color glass filter having a characteristic of blocking a light beam in an infrared region only at a portion through which a light beam entering a line sensor for reading red information passes. The image reading device according to claim 3.