JPH11331497A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of eliminating the irregularity of printing by improving the distribution of illuminance in the state of ripples at the reading line of a document at a low cost. SOLUTION: The image reader is provided with a case 10 forming a longitudinal space 11 by extending in a main scanning direction and forming an upper opening 12, which is to be connected with this space 11 and to which a transparent cover 2 is fitted, and plural light sources 21 arranged so as to be lined in the main scanning direction inside of the case 10 and at prescribed intervals and illuminates a reading line L in a document D to be carried in close contact with the cover 2 by light from the plural light sources 21 to focus reflected light from the document D at an image sensor chip 20 arranged inside of the case 10. The reader 1 is provided with irradiated light quantity reducing means 15 and 16 for reducing a radiating light quantity to an area where illuminance becomes large according to the distribution of illuminance at the reading line L.

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 configured to illuminate a reading line of a document and focus light reflected from the document on an image sensor chip.

[0002]

2. Description of the Related Art FIG. 18 shows a cross-sectional structure of an example of a conventional image reading apparatus. The image reading apparatus 1 is configured as a close contact type, and a long side in the main scanning direction is provided at the bottom of a case 10 made of resin or the like in which a long internal space 11 having a uniform cross section is formed. Rectangular substrate 2 having
Is attached. The substrate 2 has a light source 21 such as an image sensor chip 20 and an LED chip in a length range corresponding to the image reading width as shown in FIG.
Are mounted in a row in the main scanning direction. The case 10 has an upper opening 12 connected to the internal space 11, and the transparent cover 3 is fitted into the opening 12. A lens array 4 between the read line L set on the transparent cover 3 and the image sensor chip 20 for focusing a bright and dark image along the read line L on the image sensor chip 20 at the same magnification as the erect image. Is arranged.

[0003] The image reading apparatus 1 configured as described above.
Then, the transparent cover 3 is rotated by the rotation of the platen roller P.
The original D is conveyed in a state in which the original D is brought into close contact with the light source. The light is focused on the sensor chip 20. Then, in each image sensor chip 20, an image signal is output after being stored in a phototransistor (not shown) as an analog signal corresponding to the amount of received light. This output is performed continuously and serially, for example, from the image sensor chip 20 mounted on one end side in the main scanning direction to the image sensor chip 20 mounted on the other end side.

[0004]

However, in a configuration in which a plurality of point light sources 20 such as LED chips are arranged at regular intervals as in the image reading apparatus 1, the distance from each light source 20 is minimized. In the area of the read line L and its vicinity, the illuminance increases. That is, in a configuration having a plurality of point light sources 20, the illuminance on the reading line L is not uniform at each location, and
This results in a ripple-like illuminance distribution as shown in FIG.

When an image signal is output from the phototransistor, charges remain in the phototransistor. If the remaining charges are not sufficiently discharged before holding the next image signal, Are mixed with the next output image signal and output together. The amount of this residual charge is affected by the amount of light received by the phototransistor.
Not only the print state (print density of each pixel) but also the lighting condition of the read line L. Therefore, when a ripple-like illuminance distribution is generated in the read line L, the residual charge amount varies for each phototransistor due to the distribution, so that each pixel output from the phototransistor corresponds to each pixel. The degree of influence of illuminance differs for each of the image signals. For this reason, when printing is performed based on such image data, unevenness occurs in print density due to the illuminance distribution on the read line L, resulting in poor reproducibility.

In order to improve the ripple-like illuminance distribution on the read line L to solve such a problem, the point light sources 20 may be densely arranged. However, this requires a large number of light sources 20 and costs. It is not preferable because it causes up.

The present invention has been conceived in view of the above-mentioned circumstances, and is an image reading apparatus capable of improving a ripple-like illuminance distribution on a reading line of a document at low cost and eliminating printing unevenness. It is an object to provide a device.

[0008]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, the image reading apparatus provided by the present invention has a case in which a longitudinal space is formed so as to extend in the main scanning direction, and an upper opening which is connected to the space and into which a transparent cover is fitted is formed. When,
A plurality of light sources arranged in a row in the main scanning direction inside the case, and arranged at predetermined intervals, comprising: a reading line for a document conveyed in close contact with the transparent cover; An image reading device configured to illuminate with light from the plurality of light sources and focus reflected light from the document on an image sensor chip arranged inside the case, wherein It is characterized in that an irradiation light amount reducing means for reducing the irradiation light amount to the region is provided.

In the above-described image reading apparatus, the irradiation light amount to a predetermined region in the reading line, that is, the region where the illuminance is conventionally large in the reading line, is reduced by the irradiation light amount reducing means. For this reason, a situation in which the illuminance becomes extremely large in a certain area on the read line is avoided, and the illuminance distribution on the read line is improved. Therefore, the influence of the residual charge due to the illuminance distribution is substantially uniform for each image signal corresponding to each pixel, and eventually,
The print density unevenness due to the illuminance distribution is improved, and the print reproducibility of the read image is also improved.

In a preferred embodiment of the present invention, the irradiating light amount reducing means protrudes toward the internal space between each of the light sources and the reading line, and is provided at a position above the internal space. A light-shielding portion formed integrally with the member or the case,
Further, the light-shielding member or the light-shielding portion shields light illuminated in a region where the illuminance is at a peak in the reading line and in the vicinity thereof when neither of them is provided, and projects to the internal space side. It is also possible to have a configuration in which the projections have different shapes and the projections correspond to the arrangement of the light sources on the substrate.

That is, in the image reading apparatus, conventionally, a part of the light traveling toward the region where the illuminance of the reading line is large is changed to the irradiation light amount reducing means constituted by the light shielding member or the light shielding portion. , So that the light does not reach the reading line. Specifically, the light is shielded by the light-shielding member or the projection of the light-shielding portion. Since the projection is formed so as to protrude into the internal space through which the light from each of the light sources passes, it is possible to satisfactorily block light traveling toward the reading line.

In addition, since each projection is provided regularly at a position corresponding to the arrangement of the light sources, for example, just above a straight line where the distance between each light source and the reading line is minimized, each projection is provided. Otherwise, the light traveling toward the region where the illuminance would have been increased can be mainly blocked.

The light-shielding member or the light-shielding portion has a sufficient effect if part of the light to the region where the illuminance in the reading line is likely to be large is blocked by the convex portion. The overall shape of the light shielding portion may be appropriately designed. However, depending on the overall shape of the light-shielding member or the light-shielding portion, a difference appears in the effect of improving the illuminance distribution in the reading line. Therefore, the light-shielding is performed in accordance with the ripple shape of the illuminance distribution (see FIG. 20). It is preferable that the member or the light-shielding portion has a ripple-shaped uneven shape or a shape close to the shape. As described above, if the light-shielding member or the light-shielding portion is formed in a ripple shape in accordance with the illuminance distribution, the illuminance distribution in the read line can be more appropriately improved, and the uniformity of the illuminance in the read line can be further ensured. be able to.

Further, since the light-shielding member or the light-shielding portion is made of, for example, a resin, it can be easily formed into a desired shape and can be formed at a low cost.
In particular, since the light-shielding portion is integrally molded with the case and the resin by molding or the like, the light-shielding portion can be formed at a lower cost, and has an advantage that the labor for assembling into the case can be omitted. .

In the above case, in order to efficiently illuminate the reading line of the original with the light emitted from each of the light sources, the light source may be formed of a white resin having a high light reflectance. Preferably, the light-shielding member or the light-shielding portion is also formed of a white resin so that light other than light to be shielded efficiently reaches the reading line. Of course, the light-shielding surface of the light-shielding member or the light-shielding portion may be configured as black, and the other surface may be configured as white.

In a preferred embodiment of the present invention, the irradiating light amount reducing means is configured to reduce a part of light to be irradiated to a region where the illuminance on the reading line is large when the means is not provided. It is configured to escape from the upper opening to the outside of the case.

That is, in the image reading apparatus, part of the light traveling toward the region where the illuminance is increased is not blocked, but part of the light traveling toward the region where the illuminance is increased in the reading line of the document. Is intentionally released to the outside by the irradiation light amount reducing means. Even in the case where the irradiation light amount reducing means is configured in this manner, the irradiation amount to the area where the illuminance on the reading line is large can be reduced, and the illuminance on the reading line can be made uniform.

Further, in a preferred embodiment, the irradiation light amount reducing means is a plurality of recesses formed in a direction in which the upper opening communicates with the internal space in a direction to retreat from the reading line. . Such a concave portion may be formed in the case, or may be formed in a member separate from the case, and may be attached to the case. Further, it is preferable that the recess is formed corresponding to the arrangement of the light source on the substrate.

[0020] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is an exploded perspective view of an image reading apparatus according to a first embodiment of the present invention, FIG. 2 is a plan view showing a main part of the image reading apparatus, and FIG. II
FIG. 4 is a sectional view taken along the line IV-IV of FIG. 2, and FIG. 5 is a sectional view taken along the line VV of FIG. In addition,
The image reading apparatus shown in these figures is configured as a close contact type, and in these figures, the same members and elements as those shown in the drawings referred to for describing the conventional example are used. Are denoted by the same reference numerals.

As shown in FIG. 1, the image reading apparatus 1 includes a case 10 formed of a synthetic resin or the like,
A transparent cover 3 such as a glass plate, a long rectangular substrate 2,
It is roughly configured with an elongated lens array 4.

As best shown in FIGS. 1 to 5,
The case 10 has an internal space 11 formed so as to extend longitudinally in the main scanning direction.
Upper opening 12 and lower opening 13 are formed, respectively, and are formed in a relatively elongated box shape extending in a certain direction as a whole. The internal space 11 has a shape in which an upper side is bent toward the lens array 4 in a sectional view, and a reading line through which light from a plurality of light sources mounted on the substrate 2 is set on the transparent cover 3. L is favorably guided.

The inner surfaces 11a and 11b constituting the internal space 11 in the case 10 reflect light efficiently so that light from each light source 21 is guided to the reading line L. It is preferable to use a white resin or a white sheet having high reflection efficiency. Of course, the entire case 10 may be formed of a white resin or the like.

The case 10 further includes a plurality of protrusions 1 protruding toward the lens array 4 at an upper position of the internal space 11 as well shown in FIGS.
A first light-shielding portion 15 having 5a and a second light-shielding portion 16 having a plurality of convex portions 16a protruding toward the transparent cover 2 (upward) are formed integrally with the case 10, respectively. In addition, these light shielding units 15 and 16 constitute an irradiation light amount reducing unit.

As best seen in FIGS. 1 and 2,
Each of the projections 15a of the first light-shielding portion 15 has a constant thickness and is formed in a triangular shape in plan view.
5 has a wavy shape as a whole. A plurality of light sources 21 are arranged on the substrate 2 at regular intervals so as to be arranged in the main scanning direction as described later. It is formed corresponding to. That is, the top portion of each convex portion 15a are respectively provided immediately above distance is the straight lines L ₁ to the most shortened between the reading line L of each light source 21 and the document D.

As described in the conventional example, case 1
In the image reading apparatus 1 is formed such that the internal space 11 has a uniform cross section at 0, the intersection position between the straight line L ₁ and the read line L, the illuminance at the reading line L is most larger area. The illuminance decreases when the distance from this region increases, and the illuminance between the adjacent convex portions 15a becomes the lowest. Therefore, the read line L
If the first light-shielding portion 15 is formed in a wave shape corresponding to the illuminance distribution in the above, the amount of light to be shielded is increased in the region where the illuminance is large, and the illuminance in the read line L is made uniform. The illuminance distribution at L is improved.

As best shown in FIGS. 2 to 5,
Each of the convex portions 16a of the second light-shielding portion 16 is formed into a block shape having a uniform rectangular cross section, and these are formed regularly in accordance with the arrangement of the light sources 21. In other words, the second light-shielding section 16 is designed to mainly shield the area where the illuminance on the read line L is larger than a certain level, thereby improving the illuminance distribution on the read line L.

The transparent cover 2 is fitted into the upper opening 12, and a platen roller P rotatable by a driving force (not shown) is disposed at a position facing the surface of the transparent cover 2. That is, by rotating the platen roller P, the original D is sandwiched between the transparent cover 2 and the platen roller P, and the reading surface of the original D is brought into close contact with the transparent cover 2. Conveyed. The conveyance of the document D can be selected from intermittent transfer and continuous transfer by controlling the rotation of the platen roller P. In this embodiment, any transfer method may be used, and may be appropriately selected.

On the other hand, the lower opening 13 is provided with the substrate 2
The substrate 2 is held in the case 10 by two attachments 5 and 5.
That is, each of the attachments 5 and 5 is
0, and the locking holes 50, 50 of the attachments 5, 5 are locked to the engaging projections 51, 51 provided on the outer surface of the case 10, so that the substrate 2 is Installed.

As clearly shown in FIG. 1, the substrate 2
Has a plurality of image sensor chips 20 mounted on a portion from one side in the width direction so as to be arranged in a row in the longitudinal direction, while a plurality of light sources 2 are provided on a portion from the other side.
1 are implemented at regular intervals.

If the image reading apparatus 1 is an A4 width original D
Is configured to read at a reading density of 8 dots / mm, it is necessary to arrange 1,728 light receiving elements in the reading width direction. For example, 96 light receiving elements (phototransistors) are built. When the image sensor chip 20 is configured as described above, a total of 18 image sensor chips 20 are mounted on the substrate 2.

It should be noted that the above image reading device 1
When the image reading device 1 is configured to read the image D in black and white, an LED or the like is used as the light source 21, and when the image reading device 1 is configured to read the document D having the A4 width. For example, 14 light sources 21 are mounted. Of course, the image of the document may be read in color using the red, green, and blue light sources.

As best seen in FIGS. 2 to 4,
The lens array 4 includes a plurality of selfoc lenses 4 on a block-shaped lens holder 40 extending in the main scanning direction.
1 are held in a row in the main scanning direction. The lens array 4 is disposed between the reading line L and the image sensor chip 20, and receives light reflected from a document D conveyed in close contact with the transparent cover 2 by the image sensor chip 20. It plays a role of focusing on the element. In this case, an original image is formed on the light receiving element at an erect equal magnification.

In the image reading apparatus 1 having the above-described structure, the document D from which an image is to be read is conveyed by the rotation of the platen roller. In this process, the light emitted from each of the light sources 21 travels inside the internal space 11. The document D is illuminated. In this case, the image reading device 1 has a configuration in which the plurality of point light sources 21 are arranged in the longitudinal direction of the substrate 2, so that there is a concern that a large variation in illuminance may occur on the reading line L. . However, as described above, since the first light-shielding portion 15 and the second light-shielding portion 16 are formed in the case 10 so as to protrude toward the internal space 11, respectively, the reading is performed. Illumination variations on the line L are significantly reduced. As described above, in the image reading apparatus 1, there is no need to be so concerned about variations in the illuminance on the reading line L. Therefore, in order to improve the illuminance distribution on the reading line L, many light sources 21 are densely arranged. There is no need to deal with this, which is advantageous in terms of cost.
In addition, the first light shielding unit 15 and the second light shielding unit 16
Since it is formed integrally with the case 10 by die molding or the like, this point is also advantageous in cost.

The light reflected by illuminating the document D reaches the lens array 4 and is converged by the lens array 4 so that the light receiving element (phototransistor) of each of the image sensor chips 20 corrects the document image. An image is formed at 1: 1 magnification, and image information is held in each phototransistor as an analog image signal. Then, image signals are serially output from the respective phototransistors. In the image reading device 1, since the illuminance distribution in the read line L is improved, the influence of the residual charge due to the illuminance distribution is substantially uniformed for each pixel (phototransistor). That is, when printing is performed based on the image signals output from the respective phototransistors, unevenness in print density due to illuminance variation in the read line L is improved.

In the image reading apparatus 1, the case 10 has the first light-shielding portion 15 and the second light-shielding portion 1.
6 are formed, but these light shielding members 1
A configuration in which any one of 5 and 16 may be formed.

The projection line 15a of the first light-shielding portion 15 has a triangular shape in plan view, but the reading line L when the light-shielding portions 15 and 16 are not formed.
May be formed in a ripple shape as shown in FIG. 6 corresponding to the illuminance distribution in FIG.
a may be formed in a plurality.

Of course, the configuration of the second light-blocking section 16 can be changed as appropriate. For example, a plurality of blocks each having a triangular cross section may be formed, or a plurality of blocks may be formed in a ripple shape.

The present invention can be applied to the image reading apparatus 1 as shown in FIG. 8 in which the so-called light guide member 6 is accommodated in the internal space 11 of the case 10. The light guide member 6 is formed of, for example, a transparent resin such as an acrylic resin such as PMMA, and is used to efficiently guide the light from each of the light sources 21 to the reading line L.

Next, an image reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 9 is a cross-sectional view of the image reading apparatus according to the second embodiment of the present invention, FIG. 10 is another cross-sectional view of the image reading apparatus of FIG. 9, and FIG. FIG. 12 is a perspective view illustrating a first light shielding member used in the reading device, and FIG. 12 is a perspective view illustrating a second light shielding member used in the image reading devices of FIGS. 9 and 10.

The basic configuration of the image reading apparatus 1A is the same as that of the image reading apparatus 1 according to the first embodiment described above.
Is substantially the same as the image reading apparatus 1A of the present embodiment.
Is different from the image reading device 1 of the first embodiment in that
This is a configuration of an irradiation light amount reducing unit. In other words, in the first embodiment, the first
Although the light-shielding part 15 and the second light-shielding part 16 constitute the irradiation light amount reducing means, in the present embodiment, as shown in FIGS. 9 and 10, the first light-shielding member formed separately from the case 10. 6 and the second light-blocking member 7 constitute the irradiation light amount reducing means.

As shown in FIG. 11, the first light shielding member 6
Has a shape in which a plurality of protrusions 60 are regularly formed on one side of a long flat plate. These projections 60 have a triangular shape in plan view, and their top positions correspond to the arrangement of the light sources 21 mounted on the substrate 2. That is, in a state where the first light shielding member 6 is incorporated in the case 10, the distance between each of the light sources 21 and the reading line L is the same as that of the convex portion 15a of the first light shielding portion 15 of the first embodiment. It is located just above the minimum straight line. After all, when the first light shielding member 6 is incorporated in the case 10, the first light shielding member 6 has the same function as the first light shielding part 15, thereby improving the illuminance distribution on the reading line L. Can be. A plurality of projections 61 are formed on the lower surface of the first light shielding member 6. These projections 61 are fitted into engagement holes 62 formed in the case 10, and Is attached to the case 10.

As shown in FIG. 12, the second light shielding member 7
Is configured such that a plurality of block-shaped convex portions 70 having a rectangular cross section are regularly formed on a flat plate.
These projections 70 are also formed corresponding to the arrangement of the light sources 21, and when the second light shielding member 7 is incorporated in the case 10, the second light shielding member 7 is in the first position.
It has the same function as the second light shielding unit 16 of the embodiment. That is, the illuminance distribution on the read line L is also improved by the second light blocking member 7. In addition,
A plurality of projections 71 are also formed on the lower surface of the second light shielding member 7, and these projections 71 are fitted into engagement holes 72 formed in the case 10, whereby the second light shielding member 7 is It is attached to the case 10.

Of course, the projection 60 of the first light shielding member 6
May be formed in a rectangular shape in a plan view, or may be formed in a ripple shape corresponding to the illuminance distribution on the reading line L when the light shielding members 6 and 7 are not formed. Further, the cross-sectional shape of the second light-blocking member 7 can also be changed as appropriate, and the idea of the present embodiment is also applicable to an image reading apparatus having a configuration in which a light guide member is accommodated in the internal space 11. is there.

Next, an image reading apparatus according to a third embodiment of the present invention will be described with reference to FIGS. 13 is a plan view of a main part of an image reading apparatus according to a third embodiment of the present invention, FIG. 14 is a cross-sectional view taken along line XIV-XIV of FIG. 13, and FIG.
It is sectional drawing which follows the XV-XV line.

The basic structure of the image reading apparatus 1A is substantially the same as that of the image reading apparatus 1 according to the first and second embodiments described above. The difference from the image reading device 1 of the second embodiment is the configuration of the irradiation light amount reducing unit.
That is, in the first and second embodiments, a part of the light to be illuminated on the reading line L is shielded by the irradiation light amount reducing means. However, this is adopted in the present embodiment. The irradiating light amount reducing means is designed to intentionally allow a part of the light to be illuminated on the reading line L to escape to the outside of the case 10.

More specifically, as shown in FIGS. 13 to 15, the irradiation light amount reducing means includes a flange 1 of the case 10 formed so as to cover an upper portion of the internal space 11.
It is configured as a plurality of recesses 15B regularly arranged in 5A. Each of the recesses 15 </ b> B is formed in a triangular cut shape in a plan view, and the deepest portion is formed corresponding to the arrangement of the light source 21 mounted on the substrate 2. That is, of the light emitted from the read line L, more light to be emitted to the region where the illuminance on the read line L becomes large when the irradiation light amount reducing means is not provided is made to escape. I have. Therefore,
By providing the irradiation light amount reducing means, that is, providing the plurality of concave portions 15B, the illuminance on the read line L is made uniform, and the illuminance distribution is improved.

The shape of the recess 15B is not limited to a triangular shape in a plan view, but may be a ripple shape as shown in FIG. 16 or a rectangular shape as shown in FIG. .

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an image reading device according to a first embodiment of the present invention.

FIG. 2 is a plan view illustrating a main part of the image reading apparatus.

FIG. 3 is a sectional view taken along the line II-II of FIG. 2;

FIG. 4 is a sectional view taken along line III-III in FIG. 2;

FIG. 5 is a sectional view taken along line IV-IV in FIG. 2;

FIG. 6 is a plan view showing a main part of a modification of the image reading apparatus.

FIG. 7 is a plan view of a main part showing another modification of the image reading apparatus.

FIG. 8 is a plan view of a main part showing still another modified example of the image reading apparatus.

FIG. 9 is a sectional view of an image reading apparatus according to a second embodiment of the present invention.

FIG. 10 is another sectional view of the image reading apparatus of FIG. 9;

FIG. 11 is a perspective view illustrating a first light blocking member used in the image reading apparatuses of FIGS. 9 and 10;

FIG. 12 is a perspective view illustrating a second light shielding member used in the image reading apparatuses of FIGS. 9 and 10;

FIG. 13 is a plan view of a main part of an image reading apparatus according to a third embodiment of the present invention.

14 is a sectional view taken along the line XIV-XIV in FIG.

FIG. 15 is a sectional view taken along the line XV-XV in FIG.

FIG. 16 is a plan view showing a main part of a modification of the image reading apparatus of FIG. 13;

FIG. 17 is a main part plan view illustrating another modification of the image reading apparatus in FIG. 13;

FIG. 18 is a sectional view of a conventional image reading apparatus.

FIG. 19 is a plan view of a substrate of the image reading device of FIG. 18;

20 is a diagram illustrating an illuminance distribution on a reading line of the image reading device in FIG.

[Explanation of symbols]

 1, 1A, 1B Image reading device 2 Substrate 3 Transparent cover 4 Lens array 6 First light shielding member 7 Second light shielding member 10 Case 11 Internal space (of case) 12 Opening (of case) 15 First light shielding unit (of case) 16) Second light-shielding part (of the case) 20 Image sensor chip (mounted on the board) 21 Light source (mounted on the board) D Document L Reading line

Claims (6)

[Claims] 1. A case in which a longitudinal space is formed so as to extend in the main scanning direction, and an upper opening which is connected to the space and into which a transparent cover is fitted is formed. A plurality of light sources arranged in a row and arranged at predetermined intervals,
Illuminating a reading line of a document conveyed in close contact with the transparent cover with light from the plurality of light sources, and converging reflected light from the document on an image sensor chip disposed inside the case. An image reading device configured to perform the above operation, comprising: an irradiation light amount reducing unit configured to reduce an irradiation light amount to a predetermined area in the reading line. 2. The irradiation light amount reducing means protrudes toward the internal space between each of the light sources and the reading line, and is integrated with a light shielding member or the case attached to an upper position of the internal space. The image reading device according to claim 1, wherein the image reading device is a formed light shielding portion. 3. The light-shielding member or the light-shielding portion, when neither of them is provided, shields light illuminated in a region where the illuminance on the reading line is at a peak and in the vicinity thereof, and shields the internal space. The image reading device according to claim 2, further comprising convex portions protruding to the side, and wherein the convex portions correspond to an arrangement of a light source on the substrate. 4. The irradiation light amount reducing means, when this means is not provided, transmits a part of light to be irradiated to a region of the reading line where illuminance is large from the upper opening to the outside of the case. The image reading device according to claim 1, wherein the image reading device is configured to escape to the image reading device. 5. The illuminating light amount reducing unit according to claim 4, wherein a plurality of concave portions are formed in a region communicating with the upper opening and the internal space, the concave portions being recessed in a direction to retreat from the reading line. Image reading device. 6. The image reading device according to claim 5, wherein the recess is formed corresponding to an arrangement of the light source on the substrate.