JP2011139201A - Linear lighting device and image reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear lighting device that improves a utilization efficiency of irradiation light from a light source, and facilitates adjustment of the ratio between direct light and indirect light according to the reflectance, the shape or the like of a reflecting mirror, and also to provide an image reading device. <P>SOLUTION: The linear lighting device includes a first plane (A) facing substantially parallel to an irradiation surface of an LED 2<SB>k</SB>, on a light-incident surface 6, and at least two continuous reflecting surfaces of a reflecting surface C on the side of the light-incident surface and a reflecting surface D on the side of an emission surface 7 between the lower end of the first plane (A) and the lower end of the emission surface. The intersection line of the reflecting surface C on the side of the light-incident surface and the reflecting surface D on the side of the emission surface is set lower than the upper end of the first plane (A). Meanwhile, the intersection line of the reflecting surface D on the side of the emission surface and the emission surface 7 is set at substantially the same height as that of the intersection line of the reflecting surface C on the side of the light-incident surface and the reflecting surface D on the side of the emission surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a line illumination device used in an image reading apparatus such as a copying machine, an image scanner, or a facsimile, and more particularly to a line shape used in an image sensor unit that irradiates a reading surface of a document and reads reflected light. The present invention relates to an illumination device and an image reading device.

2. Description of the Related Art Conventionally, an image reading apparatus used in a reduction optical system used for a copying machine, a scanner, a facsimile, or the like includes a line illumination device using LEDs as an illumination device.
This is by arranging one end surface in the longitudinal direction of a rod-shaped light guide extending in the longitudinal direction as a light incident surface, and arranging a plurality of light sources composed of LEDs or the like along the light incident surface in the vicinity of the light incident surface. In this structure, irradiation light emitted from a light source is irradiated to an irradiation point of a document from an emission surface provided along the longitudinal direction of the light guide through the light guide.

In addition, in the image reading apparatus described in Patent Document 1, a plurality of LED light sources 401 arranged on the substrate 400 and a condensing lens (light guide) 402 configured integrally with the LED light source 401 are used. Proposals have been made to irradiate in a direction inclined with respect to the normal direction. (See Figure 14)
With this configuration, the irradiation light emitted from the LED 401 is irradiated obliquely upward toward an irradiation point of a document (not shown). Irradiation light is reflected by the document, and the reflected light (read image) is redirected by a plurality of reflection mirrors 402 and guided to the line sensor 404 via the imaging lens 403 for reading.

  By the way, since this line-shaped illumination device needs to irradiate the irradiation point of the document from two directions, there are two sets of illumination devices, and there is a problem that the number of parts increases and the cost increases. In addition, since the assembly work is complicated, there is a problem that man-hours increase.

In order to solve this problem, an image reading apparatus described in Patent Document 2 has been proposed.
That is, a plurality of LED light sources 501 arranged on the substrate 500, a light guide body 502 that irradiates an irradiation point of a document with irradiation light emitted from the LED light sources 501, and an exit surface 503 of the light guide body 502. The reflector 505 (reflecting mirror) having the reflecting surface 504 is provided. (See Figure 15)

JP 2004-170858 A Japanese Patent Laid-Open No. 2007-5860

However, in the configuration described in Patent Document 2, since the irradiation surface of the LED light source 501 is arranged in parallel with the mounting surface of the substrate 500, it is necessary to irradiate obliquely upward toward the irradiation point of the document. . For this reason, it is necessary to turn the irradiation surface of the LED light source 501 obliquely upward by fixing the substrate 500 diagonally, and there is a problem that the number of man-hours for adjustment and the like increases at the time of assembly and the cost increases.
In addition, since the irradiation light emitted from the exit surface 503 of the light guide body 502 at a shallow angle is removed as a flare component, the irradiation light irradiated to the irradiation point of the document is reduced, and the irradiation light from the LED light source 501 is reduced. There was a problem that utilization efficiency decreased.
Furthermore, in order to change the ratio of direct light and indirect light (reflected light by the reflector 505) according to the reflectance and shape of the reflective surface 504, the shape of the light guide 502 needs to be significantly changed. It was.

  The present invention has been made in view of such circumstances, and is a line that improves the utilization efficiency of irradiation light from a light source and allows easy adjustment of the ratio of direct light and indirect light according to the reflectivity, shape, etc. of the reflector. It is an object to provide a state illumination device and an image reading device.

  The line illumination device according to claim 1, wherein the line illumination device is arranged along the substrate, a plurality of light sources arranged linearly on the substrate, and the light from the light source in two directions from the side surface in the longitudinal direction. In a line-shaped illuminating device comprising a rod-shaped light guide that irradiates the light and a reflecting mirror that intersects one light in the two directions with the other light, the light guide is provided along the longitudinal direction. A light incident surface provided opposite to the light emission surface, and a plurality of reflection surfaces provided between the light emission surface and the light incident surface, wherein the light emission surface is convex. The light incident surface is provided with a flat surface facing substantially parallel to the irradiation surface of the light source, and at least the light incident surface side between the lower end of the flat surface and the lower end of the output surface. Two reflecting surfaces, which are a reflecting surface and an exit surface side reflecting surface, are provided, and the light incident surface side reflecting surface and the exit surface side opposite surface are provided. The line of intersection with the surface is lower than the upper end of the plane, and the line of intersection between the exit surface side reflecting surface and the exit surface is the intersection line between the light incident surface side reflecting surface and the exit surface side reflecting surface. It is characterized by having approximately the same height.

  The image reading apparatus according to claim 2, arranged along the substrate, a plurality of light sources arranged linearly on the substrate, and the light from the light source in two directions from the side surface in the longitudinal direction. In an image reading apparatus using a line-shaped illumination device including a rod-shaped light guide to be irradiated and a reflecting mirror that intersects one light in the two directions with the other light, the light guide is A light emitting surface provided along the light emitting surface, a light incident surface provided to face the light emitting surface, a plurality of reflective surfaces provided between the light emitting surface and the light incident surface, The exit surface is formed in a convex shape, and the light incident surface includes a plane that faces substantially parallel to the irradiation surface of the light source, and at least between the lower end of the plane and the lower end of the exit surface The light incident surface side reflective surface and the light exit surface side reflective surface are provided with two continuous reflective surfaces, and the light incident surface side reflective surface is provided. And the exit surface side reflecting surface is lower than the upper end of the plane, and the intersecting line between the exit surface side reflecting surface and the exit surface is the incident surface side reflecting surface and the exit surface side. The height is substantially the same as the line of intersection with the reflecting surface.

As described above, by providing a plane that faces the irradiation surface substantially in parallel, the separation of irradiation light irradiated in two directions can be improved, and the utilization efficiency of irradiation light can be improved.
In addition, the ratio of the direct light and indirect light can be easily adjusted by changing the position in the height direction of the line of intersection between the light incident surface side reflective surface and the light exit surface side reflective surface. It becomes easy to change the ratio of the amount of irradiation light according to the above, and the degree of freedom in designing the lighting device can be increased.

FIG. 1 is a diagram showing the structure of a copying machine to which the present invention can be applied. FIG. 2 is a diagram showing the structure of the reading unit of the copying machine. FIG. 3 is a perspective view showing the structure of the light source unit 35. FIG. 4 is a cross-sectional view showing the structure of the light source unit 35. FIG. 5 is a top view showing the structure of the substrate 1. FIG. 6 is a diagram showing a state of light emitted from the light source unit 35 to which the present invention can be applied. FIG. 7 is a diagram illustrating the relationship between “Δd” and the ratio of direct light / indirect light. FIG. 8 is a diagram illustrating a state of light irradiated from the LED 2 _k in the light guide 3 to which the present invention can be applied. FIG. 9 is a diagram illustrating a state of light irradiated from the LED 2 _k in the light guide 3 as an example of comparison. FIG. 10 is a diagram showing the light distribution characteristics of the light source unit 35 to which the present invention can be applied. FIG. 11 is a diagram illustrating light distribution characteristics of the light source unit 35 that emits light only in one direction as an example of comparison. FIG. 12 is a diagram showing the illuminance distribution in the sub-scanning direction at the position of the irradiation point of the original 34 of the light source unit 35 to which the present invention can be applied. FIG. 13 is a diagram showing a comparative example of the illuminance distribution with respect to the change “Δl” in the height direction at the position of the irradiation point of the document 34 depending on the presence or absence of the reflecting mirror 12. FIG. 14 is a diagram illustrating an example of a conventional image reading apparatus. FIG. 15 is a diagram illustrating an example of another conventional image reading apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings as examples of a copying machine in which an image reading apparatus is incorporated.

  FIG. 1 is a diagram showing a structure of a copying machine to which the present invention can be applied, and FIG. 2 is a diagram showing a structure of an image reading unit of the copying machine. In FIGS. 1 and 2, reference numeral 21 denotes a copying machine body, which includes an image reading unit 30 and an image forming unit 40. The image reading unit 30 has a so-called image scanner function, and is configured as follows.

That is, a platen glass 31, a platen cover 32, and a carriage 33 are provided.
The platen cover 32 is provided so as to cover the platen glass 31. The platen cover 32 blocks outside light and facilitates reading of the document 34 on the platen glass 31. The carriage 33 is a reduction optical system image reading device, and includes a light source unit 35, a plurality of reflection mirrors 36, an imaging lens 37, and a line sensor 38.

  With this configuration, the irradiation light emitted from the light source unit 35 is irradiated onto the surface of the document 34. Irradiation light is reflected by the document 34, and the reflected light (read image) is guided to the line sensor 38 via the imaging lens 37 by changing the direction of the optical path by a plurality of reflection mirrors 36.

  The carriage 33 moves in the sub-scanning direction during scanning, and scans the entire surface of the document 34 while irradiating the document 34. The imaging lens 37 is provided on an optical path connecting the plurality of reflection mirrors 36 and the line sensor 38, and forms an image of the reflected light from the document 34 on the line sensor 38. The line sensor 38 divides and receives reflected light into, for example, three colors of red (R), green (G), and blue (B), and photoelectrically converts each of the three colors CCD (Charge Coupled Device) image sensor or the like. The light receiving element converts the received reflected light into a signal and outputs it as an image signal.

The image forming unit 40 has a so-called printer (output device) function, and is configured as follows.
That is, it includes a paper feed tray 41, a transport roll 42, a transfer unit 43, an intermediate transfer belt 44, and a fixing unit 45.
Reference numeral 41 denotes a paper feed tray that stores sheets of a predetermined size and supplies the sheets in accordance with image formation.

  A transfer unit 43 forms an electrostatic latent image from the image signal output from the line sensor 38, and forms a toner image by attaching toner. This toner image is transferred to the intermediate transfer belt 44, then transferred onto the sheet, and is pressed and heated by the fixing unit 45 to be fixed on the sheet to perform image printing.

FIG. 3 is a diagram showing a configuration of the light source unit 35 to which the present invention can be applied, and FIG. 4 is a cross-sectional view in the sub-scanning direction at a substantially central portion in the longitudinal direction (main scanning direction) of the light source unit 35.
Reference numeral 1 denotes a substrate, and the mounting surface of the substrate 1 is painted by white silk printing using, for example, titanium oxide powder or aluminum powder as a reflective material, and efficiently reflects irradiation light from the LED 2 described later. is there.

Reference numeral 2 denotes an LED that emits white light, and a plurality of LEDs 2 _k (k is a natural number) are linearly mounted on the substrate 1.
Further, as shown in FIG. 5, the LED 2 _k is mounted with “b”> “a” in which the central portion “b” is coarsely arranged and the end portions “a” are closely arranged in the main scanning direction.
In the drawing, the number of LEDs is 35 in FIG. 3, but the number of LEDs is not particularly limited.

3 is a rod-shaped light guide made of a transparent material such as acrylic, and is installed so as to cover the LED 2 _k . Reference numeral 4 denotes a frame that supports the light guide 3, and 5 denotes a connector that connects the substrate 1 to an external device (not shown).
That is, the light source unit 35 has a configuration in which the substrate 1 and the light guide 3 on which a plurality of LEDs 2 _k are mounted are mounted and supported on the frame 4 in a predetermined positional relationship, and the LED 2 _k is mounted on the mounting surface of the substrate 1. Can be irradiated substantially vertically.

The light guide 3 can be roughly divided into a light incident surface 6, an output surface 7, a first reflective surface 8, and a second reflective surface 9 along the longitudinal direction (main scanning direction). Note that the end surfaces on both sides in the longitudinal direction (main scanning direction) are reflecting surfaces (not shown). In addition, since the plurality of LEDs 2 _k are arranged in the vicinity of the light incident surface 6 in the light source unit 35, the irradiation light emitted from the LEDs 2 _k passes through the light incident surface 6 and enters the light guide 3. It is the structure to do.

The emission surface 7 is a surface facing the light incident surface 6 and is formed in a convex shape for condensing effect. For example, the surface is knurled.
The light incident surface 6 includes at least a first plane A and a second plane B, and is formed to include a first plane A that faces the irradiation surface of the LED 2 _k substantially in parallel. The intersection line between the first plane A and the second plane B is “c”.
Further, the first reflecting surface 8 located between the lower end of the exit surface 7 of the first plane A has at least two continuous reflections of the light incident surface side reflecting surface C and the exit surface reflecting surface D. The intersection line between the light incident surface side reflective surface C and the light exit surface side reflective surface D is “d”.
Further, the intersection line “e” between the exit surface side reflection surface D and the exit surface 7 is substantially the same height as the intersection line “d”.

  Note that the exit surface-side reflecting surface D may be low (“e” is lower than “d”) so as to be reversely tapered toward the exit surface 7.

Reference numeral 12 denotes a reflecting mirror, and the reflecting mirror 12 is a planar mirror having substantially the same length as the longitudinal direction (main scanning direction) of the light guide 3, for example, an aluminum plate or a reflecting surface. By being constituted by the one formed with the aluminum film, the direction of the irradiation light irradiated from the side surface in the longitudinal direction (main scanning direction) of the light source unit 35 is changed, and one light (first light beam 13) described later is changed. Is guided so that the other light (second light beam 14) intersects the irradiation point of the document 34. (See Figure 6)
Although the reflecting mirror 12 shown in FIG. 6 has a planar shape, it may be formed in an elliptical section or a parabolic section. In this case, as compared with the planar shape, the convergence of the irradiation light to the irradiation point of the optical original 34 can be improved, and the irradiation range of the irradiation light can be arbitrarily controlled.

With this configuration, a part of the irradiation light transmitted through the first plane A out of the irradiation light emitted from the LED 2 _k is directly irradiated from the emission surface 7 as the first light flux 13 (indirect light). Irradiation is substantially parallel to the document 34. Most of the other irradiating light is totally reflected by the first reflecting surface 8, and is irradiated as a second light beam 14 (direct light) directly from the emitting surface 7 to the irradiation point of the document 34. The light is condensed on the irradiation point of the original 34 by the shape portion.

Further, most of the irradiation light transmitted through the second plane B is directly irradiated onto the irradiation point of the document 34 from the direct emission surface 7 (or after being totally reflected by the second reflection surface 9 and then directly from the emission surface 7. Are emitted, and then combined with the second light flux 14 and condensed on the irradiation point of the document 34 by the convex portion of the emission surface 7.
In this way, the irradiation light from the LED 2 _k is irradiated in two different directions independent from each other from the emission surface 7.
Further, the first light beam 13 is reflected by the reflecting mirror 12 so as to intersect the irradiation point of the second light beam 14 and the document 34.

FIG. 7 is a diagram illustrating a relationship between a difference “Δd” in the height direction between the lower end of the irradiation surface of the LED 2 _k and “d” and the ratio of direct light / indirect light in the light guide 3 of the present embodiment. , 100 is a line showing a change in the ratio of direct light / indirect light due to a change in “Δd”.
According to FIG. 7, by adjusting “Δd”, it is possible to adjust the ratio between the component (direct light) irradiated substantially parallel to the document 34 and the component (indirect light) irradiated directly on the document 34. Become. For this reason, it becomes easy to change the ratio of the amount of irradiation light according to the reflectance of the reflecting mirror and the like, and the degree of freedom in designing the lighting device can be increased.

In the present embodiment, the first reflecting surface 8 (light incident surface side reflecting surface C) is 17.6 °, the second plane B is 132 °, and the second reflecting surface 9 is 62 ° with respect to the mounting surface. Tilted.
Thus, a first reflecting surface 8, and the second reflecting surface 9, with respect to the irradiation light from LED2 _k, in which totally reflects the illumination light exceeding the critical angle.
Further, “Δc” = 0.36 mm, “Δd” = “Δe” = 0.1 mm, and direct light: indirect light = 55%: 45%.
In “c”, the difference in height between the upper end of the irradiation surface of LED 2 _k and “c” is “Δc”, and the upper end of the irradiation surface and “c” are at the same height. “Δc” = 0 mm.
In “d” and “e”, the difference in height between the lower end of the irradiation surface of LED 2 _k and “d” and “e” is “Δd” and “Δe”, and the lower end of the irradiation surface and “d” , “E” is at the same height, “Δd” = “Δe” = 0 mm.
Further, at least “c” is assumed to be higher by “Δc” than the upper end of the irradiation surface of the LED 2 _k , and both “Δd” and “Δe” are lower than the height of “c”.

Here, the above-described effect will be described with reference to a diagram showing the irradiation light propagating through the light guide 3 by simulation.
Figure 8 is an example having first plane A substantially parallel to face the LED2 _k irradiation surface of the light incident surface 6, and, the second plane B, fig. 9 is the light incident surface as an example of comparison 6 Is an example of an oblique linear plane (not provided with the first plane A).

In the light guide 3 of the present embodiment in FIG. 8, a part of the irradiation light transmitted through the first plane A among the irradiation light emitted from the LEDs 2 _k arranged in the vicinity of the light incident surface 6 is: By irradiating directly from the exit surface 7 as the first light flux 13, the original 34 is irradiated substantially in parallel. Also, most of the other irradiated light is totally reflected by the first reflecting surface 8 and is emitted from the emitting surface 7 as the second light flux 14, and is projected to the irradiation point of the document 34 by the convex portion of the emitting surface 7. Focused. In addition, most of the irradiation light transmitted through the second plane B is emitted from the direct emission surface 7 to the irradiation point of the document 34 (or after being totally reflected by the second reflection surface 9 and then directly from the emission surface 7. After being emitted), it is combined with the second light beam 14 and is condensed on the irradiation point of the document 34 by the convex portion of the emission surface 7.
At this time, the first light beam 13 is converged on the irradiation point of the document 34 by the convex portion of the emission surface 7. Further, the first light beam 13 is reflected by the reflecting mirror 12 so as to intersect the irradiation point of the second light beam 14 and the original 34, so that the irradiation point of the original 34 is irradiated, and the portion to be read of the original 34 is read. It is illuminated in a line.

Similarly, in the light guide 3 in FIG. 9, all of the irradiation light emitted from the LED 2 _k disposed in the vicinity of the light incident surface 6 is transmitted through the light incident surface 6, and a part thereof is the first light flux 13. By irradiating from the direct emission surface 7, the original 34 is irradiated substantially in parallel. On the other hand, most of the other irradiated light is totally reflected by the first reflecting surface 8 and the second reflecting surface 9 so as to be irradiated from the emitting surface 7 as the second light beam 14 and directly emitted. 7 is formed by combining with a part of the irradiation light emitted from 7.
The second light beam 14 is focused on the irradiation point of the document 34 by the convex portion of the exit surface 7.

  However, in the light guide 3 shown in FIG. 9, since the first plane A is not formed on the light incident surface 6 and only a linear plane, the irradiation light transmitted near the center of this plane is the exit surface. 7 is irradiated almost uniformly. As a result, irradiation light is emitted from the vicinity of the central portion of the emission surface 7 at an angle at which the irradiation point of the original 34 is not irradiated and at an angle that is not reflected by the reflecting mirror 12, so stray light (flare component) is generated. It is what happens.

On the other hand, in the light guide 3 of the present embodiment in FIG. 8, by forming the first plane A, the first light flux 13 and the first light beam 13 are irradiated without irradiating irradiation light from the vicinity of the central portion of the emission surface 7. 2 light beams 14 can be converged. As a result, the ability to reduce the illumination light emitted at an angle that is not reflected by the reflecting mirror 12, it is possible to condense the illumination light to the irradiation point of efficiently document 34 from LED2 _k, improving the illuminance of the irradiation point it can.

  Thus, by providing the light incident surface 6 with the first plane A and the second plane B, the separability when irradiating in two directions is improved, so that the illuminance at the irradiation point, that is, The utilization efficiency of irradiation light can be improved.

Note that the solid line in the figure is for tracking the state of the irradiation light emitted from the LED 2 _k , and is actually a light beam.

FIG. 10 is a diagram showing the light distribution characteristics of the light source unit 35 to which the present invention can be applied, and FIG. 11 is a diagram showing the light distribution characteristics of the light source unit 35 that emits light only in one direction as an example of comparison.
FIG. 14 is a comparative example of the light source unit 35 according to the present embodiment in the presence or absence of the reflecting mirror 12 in the illuminance distribution in the sub-scanning direction at the irradiation point position of the document 34.
Reference numeral 200 denotes a line indicating the state with the reflecting mirror 12, and reference numeral 201 denotes a line indicating the state without the reflecting mirror 12.
As shown in FIG. 12, by using the reflecting mirror 12 to which the present invention can be applied, it is possible to maintain a stable illuminance even when the irradiation point of the document 34 changes in position in the sub-scanning direction (± 1.0 mm).

  As a result, fluctuations in the amount of reading light in the sub-scanning direction can be suppressed and the output fluctuation range can be reduced, so that density fluctuations occurring in the output image of the image reading apparatus can be reduced, and reading performance can be stabilized.

FIG. 13 is a diagram showing a comparative example of the illuminance distribution with respect to a change in position in the height direction (“Δl”) at the position of the irradiation point of the document 34 depending on the presence or absence of the reflecting mirror 12 in the light source unit 35 of the present embodiment.
Reference numeral 300 denotes a line indicating the state with the reflecting mirror 12, and reference numeral 301 denotes a line indicating the state without the reflecting mirror 12.
As shown in FIG. 13, by using the light source unit 35 that irradiates light in two directions and the reflecting mirror 12 to which the present invention can be applied, stable illuminance is maintained at 0 mm <“Δl” <3.0 mm. be able to.
This is because the illumination peak position of the first light beam 13 from the reflecting mirror 12 is shifted to the reflecting mirror side, and the illumination peak position of the second light beam 14 from the light source unit 35 is shifted to the light source side, so that the upper position of the platen glass 31 is increased. This is because a position where the peak position matches is generated.

  As a result, the peak positions of the two coincide with each other as the position of the document 34 in the height direction is changed. Therefore, the amount of decrease in output due to the height variation caused by the wrinkles, steps, and lifting of the document 34 is reduced. And the reading performance can be stabilized. For this reason, the density fluctuation generated in the output image of the image reading apparatus can be reduced, and the reading performance can be stabilized.

Incidentally, FIG. 10 to, 13, the pitch of each LED2 _k (intervals) are those 6.4 mm, at 60 using 4.3 mm, the LED light source at the end in the central portion.

  The line illumination device of the present invention is an effective technique as an image reading device such as an image scanner, a facsimile machine, a copying machine or the like.

1 Substrate 2 LED
DESCRIPTION OF SYMBOLS 3 Light guide 6 Light entrance surface 7 Output surface 13 1st light beam 14 2nd light beam A 1st plane B 2nd plane C Light input surface side reflective surface D Output surface reflective surface

Claims (2)

A substrate,
A plurality of light sources arranged linearly on the substrate;
A rod-shaped light guide that is arranged along the light source and irradiates light from the light source in two directions from a side surface in the longitudinal direction;
A reflecting mirror that crosses one light in the two directions with the other light;
In the line-shaped lighting device provided with
The light guide is
An exit surface provided along the longitudinal direction;
A light incident surface provided to face the light exit surface;
A plurality of reflecting surfaces provided between the emitting surface and the light incident surface;
With
The exit surface is formed in a convex shape,
The light incident surface includes a plane that faces the irradiation surface of the light source substantially in parallel,
Between the lower end of the plane and the lower end of the exit surface, at least two reflective surfaces that are continuous with the incident surface side reflective surface and the exit surface side reflective surface are provided,
The line of intersection between the light incident surface side reflective surface and the light exit surface side reflective surface is lower than the upper end of the plane,
The line-shaped illuminating device according to claim 1, wherein an intersection line between the emission surface side reflection surface and the emission surface is substantially the same height as an intersection line between the light incident surface side reflection surface and the emission surface side reflection surface. A substrate,
A plurality of light sources arranged linearly on the substrate;
A rod-shaped light guide that is arranged along the light source and irradiates light from the light source in two directions from a side surface in the longitudinal direction;
A reflecting mirror that crosses one light in the two directions with the other light;
In an image reading apparatus using a line illumination device comprising:
The light guide is
An exit surface provided along the longitudinal direction;
A light incident surface provided to face the light exit surface;
A plurality of reflecting surfaces provided between the emitting surface and the light incident surface;
With
The exit surface is formed in a convex shape,
The light incident surface includes a plane that faces the irradiation surface of the light source substantially in parallel,
Between the lower end of the plane and the lower end of the exit surface, at least two reflective surfaces that are continuous with the incident surface side reflective surface and the exit surface side reflective surface are provided,
The line of intersection between the light incident surface side reflective surface and the light exit surface side reflective surface is lower than the upper end of the plane,
An image reading apparatus, wherein an intersection line between the exit surface side reflection surface and the exit surface is substantially the same height as an intersection line between the light incident surface side reflection surface and the exit surface side reflection surface.