JP2018046386A - Line lighting device and image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line lighting device capable of suppressing intensity unevenness of illumination light emitted via a light guide body from a light source, and an image reading device comprising the line lighting device.SOLUTION: A line lighting device 2 includes a rod-shaped light guide body 3 extending in a first direction X and a plurality of light sources 4 disposed on an end surface 35 of one side in the first direction X of the light guide body 3, and is provided with an emission surface 30 between a first side surface 31 and a second side surface 32. The plurality of light sources 4 is provided at positions having distances from the first side surface 31 in a second direction Y different from one another. On the first side surface 31, an area between the end surface 35 and the emission surface 30 is a prism formation area 38 where a plurality of prism-shaped protrusion portions 380 is formed in the first direction X. A light shading member 6 comprising a light-scattering reflective surface 61 is provided at a position facing the prism formation area 38.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a line illumination device and an image reading device.

  In image reading devices such as scanners and copiers, the irradiation area of the illumination light on the medium is moved in the sub-scanning direction while irradiating the line-shaped illumination light extending in the main scanning direction from the line illumination device to the medium such as a document. In addition, the reflected light from the medium is detected by a sensor.

  As shown in FIG. 10, the line illumination device is arranged on a rod-shaped light guide 3 extending in the first direction X (main scanning direction) and an end face 35 on one side of the light guide 3 in the first direction X. Among the plurality of side surfaces extending in the first direction X in the light guide 3, the light guide 3 is guided between the adjacent first side surface 31 and second side surface 32. An emission surface 30 that emits light from the light source 4 incident on the light body 3 is provided (see Patent Document 1). Here, the plurality of light sources 4 are provided at positions where the distances from the first side surface 31 in the second direction Y orthogonal to the first direction X are different from each other. For example, the blue light source 4 (B), the green light source 4 (G), and the red light source 4 (R) are linearly arranged in order on the end surface 35 along the second direction Y from the first side surface 31 side. ing. Therefore, the blue light L (B), the green light L (G), and the red light L (R) emitted from the blue light source 4 (B), the green light source 4 (G), and the red light source 4 (R) The light is emitted from the emission surface 30 while traveling in the first direction X while repeating reflection between the first side surface 31 and the third side surface 33 facing the first side surface 31 in the second direction Y. In Patent Document 1, it is proposed to provide a light scattering pattern on the third side surface 33 and the fourth side surface 34 facing the second side surface 32 by printing a white paint or the like.

JP 2003-348299 A

  However, in the line illumination device described in Patent Document 1, blue light L (B), green light L (G), and red light L (R) travel inside the light guide 3 as shown in FIG. In this case, the blue light L (B) emitted from the blue light source 4 (B) closest to the first side surface 31 has a problem that intensity unevenness is likely to occur in the emitted light. Specifically, the blue light L (B), the green light L (G), and the red light L (R) are first reflected by the first side surface 31 inside the light guide 3, and then the third side surface 33. The distances D (B), D (G), and D (R) between the light beam reflected from the light guide 3 and the light beam first reflected from the third side surface 33 and emitted from the light guide 3. ), The distance D (B) of the blue light L (B) is considerably narrower than the distance D (G) of the green light L (G) and the distance D (R) of the red light L (R). For this reason, as shown in FIG. 12, intensity unevenness is likely to occur in the blue light L (B). FIG. 12 shows the intensity distribution in the first direction X of the blue light L (B) emitted from the light guide 3 when the center of the light guide 3 in the first direction X is 0 mm. The problem described with reference to FIG. 11 and the like occurs when the distance between the light source 4 and the first side surface 31 is short even when one light source 4 is arranged on the end surface 35.

  In view of the above problems, an object of the present invention is to provide a line illumination device capable of suppressing unevenness in intensity of illumination light emitted from a light source via a light guide, and an image reading device including the line illumination device. Is to provide.

  In order to solve the above-described problem, an aspect of the line illumination device according to the present invention intersects the light guide having a plurality of side surfaces extending in the first direction and the first direction of the light guide. A first light source disposed on one end face of the end faces; and a light shielding member, wherein the light guide is between a first side face and a second side face adjacent to each other among the plurality of side faces. An exit surface that emits light that has entered the light guide from the light source is disposed at a position that is spaced apart in the direction along the first direction with respect to the one end surface. Each of the plurality of prism-shaped convex portions includes a prism forming region in which a plurality of prism-shaped convex portions are arranged along the first direction in a region sandwiched between the end surface and the emission surface. A first slope and a second slope that are inclined in a direction intersecting the first side surface; Serial shielding member is at a position facing the prism forming region, characterized in that it is arranged so that the reflecting surface of the light-scattering in the prism formation region faces.

  In the present invention, the light emitted from the first light source is emitted from the emission surface while traveling in the first direction while repeating reflection on the side surface of the light guide inside the light guide. At that time, even when the first light source is disposed at a position close to the first side surface, the light emitted from the first light source partially passes through the prism-shaped convex portion inside the light guide, The light is scattered by the reflection surface of the light shielding member and enters the light guide again. For this reason, even if it is the light emitted from the first light source close to the first side surface, the intensity unevenness hardly occurs in the illumination light emitted from the emission surface.

  In another aspect of the present invention, an angle formed by the first inclined surface located on the one end surface side of the first inclined surface and the second inclined surface with the first side surface is such that the second inclined surface is different from the first side surface. A mode smaller than the formed angle can be adopted. For example, the first angle formed by the first inclined surface with the first side surface is 20 ° to 50 °, and the second angle formed by the second inclined surface with the first side surface is 90 ° to 45 °. Can be adopted.

  In another aspect of the present invention, a second light source is disposed on the one end surface at a position opposite to the first side surface along a second direction intersecting the first direction with respect to the first light source. The aspect currently performed can be employ | adopted.

  In another aspect of the present invention, a configuration is adopted in which a third light source is disposed on the one end surface at a position opposite to the first side surface along the second direction with respect to the second light source. can do.

  In another aspect of the present invention, any one of the first light source, the second light source, and the third light source is a blue light source that emits blue light, and the other is a green light source that emits green light. It is possible to adopt a mode in which the remaining one is a red light source that emits red light.

  In another aspect of the present invention, the light guide may employ a mode in which a third side surface having a light scattering pattern is disposed at a position facing the first side surface. According to this aspect, unevenness in intensity of illumination light emitted from the exit surface can be suppressed by the density of the light scattering pattern and the like.

  In another aspect of the present invention, the light guide includes a case that accommodates the light guide, and the case is provided with an opening at a position that overlaps the emission surface, and the light shielding member is included in the case. The aspect which is can be employ | adopted. According to this aspect, it is not necessary to separately provide another member in order to provide the light shielding member.

  The line illumination device according to the present invention is used in an image reading device or the like. In this case, the image reading device includes a sensor that detects reflected light of the illumination light emitted from the line illumination device.

  In an aspect of the image reading apparatus according to the present invention, an aspect having a reduction optical system that guides the reflected light to the sensor can be employed.

It is explanatory drawing of the image reading apparatus provided with the line illumination apparatus to which this invention is applied. It is explanatory drawing of the carriage used for the image reading apparatus shown in FIG. It is a perspective view which shows the principal part of the line illuminating device shown in FIG. It is explanatory drawing which shows the structure inside the case in the line illuminating device shown in FIG. It is sectional drawing when the light guide shown in FIG. 4 is cut | disconnected in the position which passes an output surface. It is explanatory drawing which shows the structure of the periphery of the prism formation area provided in the light guide of the line illuminating device shown in FIG. It is a light ray figure of the light radiate | emitted from the light source of the line illuminating device shown in FIG. It is explanatory drawing which shows the relationship between the structure of a prism-shaped convex part in the line illuminating device shown in FIG. 3, and light intensity distribution. It is explanatory drawing which shows another relationship between the structure of a prism-shaped convex part in the line illuminating device shown in FIG. 3, and light intensity distribution. It is explanatory drawing of the conventional line illuminating device. It is a light ray figure of the light radiate | emitted from the light source of the line illuminating device shown in FIG. It is explanatory drawing which shows the light intensity distribution in the line illuminating device shown in FIG.

  Embodiments of the present invention will be described below. In the drawings to be referred to in the following description, the scales are different for each member so that each layer and each member have a size that can be recognized on the drawing. Moreover, in the following description, the same code | symbol is attached | subjected and demonstrated to the part which is common in FIG.10, FIG11 and FIG.12.

(Image reading device)
FIG. 1 is an explanatory diagram of an image reading apparatus 100 including a line illumination device 2 to which the present invention is applied. FIG. 2 is an explanatory diagram of the carriage 120 used in the image reading apparatus 100 shown in FIG.

  An image reading apparatus 100 illustrated in FIGS. 1 and 2 is an optical device used as a scanner, a copying machine, or the like, and includes a frame 150 and a cover 160 that opens and closes the upper surface of the frame 150. A part of the upper surface of the frame 150 is constituted by a translucent cover 110 on which a medium M such as a document is arranged. Inside the frame 150, a carriage 120 that is movable in the sub-scanning direction Z is provided. The carriage 120 includes a line illumination device 2 that irradiates the medium M with line-shaped illumination light extending in the first direction X via the translucent cover 110, an optical system 130, and a sensor 140. Is provided. Accordingly, when the carriage 120 is moved in the sub-scanning direction Z while irradiating the medium M with the illumination light from the line illumination device 2, the illumination light irradiation area for the medium M is moved in the sub-scanning direction Z. Meanwhile, if the reflected light from the medium M (reflected light of illumination light) is detected by the sensor 140, a two-dimensional image of the medium M can be detected. Here, the optical system 130 includes three mirrors 131, 132, and 133 that guide the reflected light from the medium M to the sensor 140, and the reflected light that is guided through the mirrors 131, 132, and 133 to the sensor 140. And a lens 134 for condensing light. Therefore, the optical system 130 is configured as a reduction optical system, and the sensor 140 is configured by a charge coupled device (CCD).

(Configuration of line lighting device 2)
FIG. 3 is a perspective view showing a main part of the line illumination device 2 shown in FIG. FIG. 4 is an explanatory diagram showing an internal configuration of the case 5 in the line illumination device 2 shown in FIG. FIG. 5 is a cross-sectional view when the light guide 3 shown in FIG. 4 is cut at a position passing through the emission surface 30.

  As shown in FIGS. 3, 4, and 5, the line illumination device 2 of the present embodiment includes a rod-shaped light guide 3 extending in the first direction X (main scanning direction), and the first direction of the light guide 3. It has the some light source 4 arrange | positioned at the end surface 35 of the one side of X, and the case 5 which accommodated the light guide 3 and the light source 4 inside. Among the plurality of side surfaces extending in the first direction X in the light guide 3, light from the light source 4 incident on the light guide 3 is interposed between the adjacent first side surface 31 and second side surface 32. An exit surface 30 for exiting is provided. In the present embodiment, the emission surface 30 is provided at a position separated from the end surface 35 in the first direction X.

  In this embodiment, the light guide 3 is composed of a translucent resin molded product or the like. The light guide 3 includes a first side surface 31, a second side surface 32 adjacent to the first side surface 31, a third side surface 33 adjacent to the second side surface 32, and a fourth side surface 34 adjacent to the third side surface 33. In the rod-shaped member having a quadrangular cross section, an emission surface 30 that is inclined with respect to the first side surface 31 and the second side surface 32 is formed between the first side surface 31 and the second side surface 32. . Here, the first side surface 31 and the second side surface 32 are orthogonal to each other. The first side surface 31 and the third side surface 33 face in parallel in the second direction Y, and the second side surface 32 and the fourth side surface 34 face in parallel in the sub-scanning direction Z.

  The light guide 3 has an end face 35 (first end face) and an end face 36 (second end face) on both sides in the first direction X. Among the two end faces 35, 36, a plurality of end faces 35 are provided on one end face 35. The light source 4 is arranged. In this embodiment, since the dimension in the second direction Y of the light guide 3 is larger than the dimension in the sub-scanning direction Z, the end surface 35 is a rectangle whose long side extends along the second direction Y.

  The plurality of light sources 4 are provided on the end surface 35 at positions where the distances from the first side surface 31 in the second direction Y are different from each other. In this embodiment, the plurality of light sources 4 are linearly arranged along the second direction Y from the first side surface 31 side. In this embodiment, each of the plurality of light sources 4 includes a red light source 4 (R) that emits red light L (R), a green light source 4 (G) that emits green light L (G), and a blue light L (B). The blue light source 4 (B) that emits light, and the blue light source 4 (B), the green light source 4 (G), and the red light source 4 (R) are linearly arranged in this order along the second direction Y from the first side surface 31 side. Arranged in a shape. Therefore, when the blue light source 4 (B) is the first light source, the green light source 4 (G) is the second light source, and the red light source 4 (R) is the third light source, the end surface 35 has a second direction Y. A second light source (green light source 4 (G)) is disposed on the opposite side of the first side surface 31 with respect to the first light source (blue light source 4 (B)), and the second light source (green light source 4 in the second direction Y). A third light source (red light source 4 (R)) is disposed on the side opposite to the first side surface 31 with respect to (G)). Further, each of the plurality of light sources 4 includes a light emitting diode. In this embodiment, the red light source 4 (R), the green light source 4 (G), and the blue light source 4 (B) are sequentially turned on, and the illumination light of each color is emitted sequentially from the line illumination device 2. The emitted illumination light is acquired as an image signal by a monochrome sensor, for example. If a plurality of color sensors with red, green and blue filters are used instead of the monochrome sensor, the red light source 4 (R), the green light source 4 (G) and the blue light source 4 (B) are turned on simultaneously. Image signals can be acquired at once. However, in general, a color sensor is often expensive, and a monochrome sensor is often used.

  As shown in FIG. 3, the case 5 includes a first side plate portion 51 that overlaps the first side surface 31, a second side plate portion 52 that overlaps the second side surface 32, a third side plate portion 53 that overlaps the third side surface 33, It has a fourth side plate portion 54 that overlaps the fourth side surface 34, a first end plate portion 55 that overlaps the end surface 35, and a second end plate portion 56 that overlaps the end surface 36. Between the side plate portions 52, an opening 50 is formed in a region overlapping with the emission surface 30. In this embodiment, since the emission surface 30 is provided at a position separated from the end surface 36 in the first direction X, the opening 50 is formed in the first direction from the first end plate portion 55 and the end surface 36 of the light guide 3. It is provided at a position separated by X.

(Detailed configuration of the light guide 3 and the like)
FIG. 6 is an explanatory diagram illustrating a configuration around the prism formation region 38 provided in the light guide 3 of the line illumination device 2 illustrated in FIG. 3.

  As shown in FIGS. 3 and 6, in the light guide 3, the region sandwiched between the end surface 35 and the emission surface 30 in the first direction X on the first side surface 31 is a prism formation region 38. In the prism forming region 38, the prism-shaped convex portion 380 in which the first inclined surface 381 and the second inclined surface 382 that are inclined in the direction intersecting the first side surface 31 are adjacent in the first direction X via the top portion 383. A plurality of lines are formed along the first direction X.

  Here, of the first inclined surface 381 and the second inclined surface 382, the first angle θa formed by the first inclined surface 381 positioned on the end surface 35 side with the first side surface 31 is the first angle θa formed by the second inclined surface 382 and the first side surface 31. It is smaller than the two angles θb. In the present embodiment, from the results described later with reference to FIGS. 8 and 10, the first angle θa is set from 20 ° to 50 °, and the second angle θb is set from 90 ° to 45 °.

  In the light guide 3, a light scattering pattern 37 is provided on the third side surface 33 that faces the first side surface 31 in the second direction Y by printing white paint or the like. Note that, similarly to the third side surface 33, the light scattering pattern 37 may also be provided on the fourth side surface 34 facing the second side surface 32 in the sub-scanning direction Z by printing white paint or the like.

  Further, in the line illumination device 2 of the present embodiment, a light shielding member 6 is provided at a position facing the prism forming region 38 with the light scattering reflective surface 61 facing the prism forming region 38. In this embodiment, the light shielding member 6 is included in the case 5. More specifically, the light shielding member 6 includes a portion of the first side plate portion 51 of the case 5 that overlaps a region sandwiched between the end surface 35 and the emission surface 30 in the first direction X of the light guide 3. Here, in the case 5, either an aspect in which only the portion corresponding to the light shielding member 6 is a light scattering reflective surface or an aspect in which the entire inner surface of the case 5 is a light scattering reflective surface may be adopted. In any case, the light scattering reflective surface 61 can be provided at a position facing the prism forming region 38. In this embodiment, the entire inner surface of the case 5 is a light scattering reflective surface. For example, the case 5 can be configured by attaching a light scattering reflective sheet to a metal plate.

(Ray trace result)
FIG. 7 is a ray diagram of light emitted from the light source 4 of the line illumination device 2 shown in FIG. FIG. 8 is an explanatory diagram showing the relationship between the configuration of the prism-shaped convex portions and the light intensity distribution in the line illumination device 2 shown in FIG. FIG. 9 is an explanatory diagram showing another relationship between the configuration of the prism-like convex portions and the light intensity distribution in the line illumination device 2 shown in FIG. 8 and 9 show the intensity distribution in the first direction X of the blue light L (B) emitted from the light guide 3 when the center of the light guide 3 in the first direction X is 0 mm. It is shown.

  In the line illumination device 2 configured as described above, the light emitted from the light source 4 travels in the first direction X while being repeatedly reflected by the third side surface 33 and the like of the light guide 3 inside the light guide 3. In the meantime, the light is emitted from the emission surface 30. At that time, when the blue light L (B) is emitted from the blue light source 4 (B) which is the first light source closest to the first side surface 31 among the three light sources 4 in the vicinity of the end surface 35 of the light guide 3. As shown in FIG. 7, part of the blue light L (B) is transmitted through the second inclined surface 382 inside the light guide 3 and then scattered by the reflection surface 61 of the light shielding member 6 to guide the light again. The light enters the body 3 as light having no directivity. The other part of the blue light L (B) is reflected by the first inclined surface 381 inside the light guide 3, then passes through the second inclined surface 382, and then scattered by the reflecting surface 61 of the light shielding member 6. Then, it again enters the light guide 3 as light having no directivity. Therefore, even the blue light L (B) emitted from the blue light source 4 (B) closest to the first side surface 31 has been described with reference to FIG. 11 and the like as shown in FIGS. Such unevenness in strength is unlikely to occur.

  FIG. 8 shows the light intensity distribution when the second angle θb is 85 ° and the first angle θa is changed to 15 °, 20 °, 25 °, 30 °, 40 °, and 50 °. As a result of the results shown in FIG. 8 and further examination of changing the angle, when the first angle θa is 15 ° or less, the reflection on the first inclined surface 381 is too small and unevenness in intensity tends to occur. In addition, when the first angle θa exceeds 50 °, there is too much reflection on the second inclined surface 382 and unevenness in strength tends to occur. Therefore, the first angle θa is preferably set to 20 ° to 50 °. However, when the first angle θa is 50 °, the strength is reduced in the vicinity of −100 mm. Therefore, the first angle θa is more preferably set to 20 ° to 40 °.

  FIG. 9 shows the light intensity distribution when the first angle θa is 30 ° and the second angle θb is changed to 45 ° and 35 °. When the second angle θb is less than 45 ° as a result of the results shown in FIG. 9 and further examination of changing the angle, there is too much reflection at the second inclined surface 382 and uneven intensity tends to occur. In addition, when the second angle θb exceeds 90 °, it is difficult to form the second slope 382. Therefore, the second angle θb is preferably set to 90 ° to 45 °. However, in consideration of molding restrictions and the like, the second angle θb is more preferably set to 85 ° to 45 °, and more preferably 85 ° to 70 °.

(Main effects of this form)
As described above, in the line illumination device 2 of this embodiment, the light emitted from the light source 4 is reflected in the first direction while being repeatedly reflected on the third side surface 33 and the like of the light guide 3 inside the light guide 3. The light exits from the exit surface 30 while traveling to X. At that time, light emitted from the first light source (blue light source 4 (R)) closest to the first side surface 31 among the plurality of light sources 4 is partially convex in the light guide 3. After passing through 380, the light is scattered by the reflection surface 61 of the light shielding member 6 and enters the light guide 3 again. For this reason, even if the light is emitted from the light source 4 closest to the first side surface 31, the intensity unevenness hardly occurs in the illumination light emitted from the emission surface 30.

Further, in this embodiment, since the light scattering pattern 37 is provided on the third side surface 33 or the like facing the first side surface 31 in the light guide 3, the light is emitted from the emission surface 30 depending on the density of the light scattering pattern 37 or the like. It is possible to suppress unevenness in intensity of the illumination light.
Further, in this embodiment, since the light shielding member 6 is configured by the portion of the case 5 that overlaps the prism forming region 38, it is not necessary to separately provide another member for providing the light shielding member 6.

(Other embodiments)
In the above embodiment, the blue light source 4 (B), the green light source 4 (G), and the red light source 4 (R) are arranged in this order from the first side surface 31 side. The present invention may be applied to. In either case, the light source closest to the first side surface 31 is the first light source, the light source next to the first side surface 31 is the second light source, and the light source next to the first side surface 31 is the third light source. Become.

  In the above embodiment, the blue light source 4 (B), the green light source 4 (G), and the red light source 4 (R) are turned on simultaneously, but the blue light source 4 (B), the green light source 4 (G), and the red light source 4 are turned on. The present invention may be applied to sequentially lighting (R).

  Moreover, in the said embodiment, although the some light source 4 was the red light source 4 (R), the green light source 4 (G), and the blue light source 4 (B), all of the some light sources 4 are white light sources. In some cases, the present invention may be applied.

  Moreover, in the said embodiment, although the three light sources 4 which consist of a 1st light source, a 2nd light source, and a 3rd light source were arrange | positioned at the end surface 35, the two light sources 4 which consist of a 1st light source and a 2nd light source are end surfaces. The present invention may be applied to the case where the first light source is disposed on the end surface 35. In addition, as long as the light source 4 is disposed within the end face 35, an optimal position may be selected and disposed as appropriate.

2 ... line illumination device, 3 ... light guide, 4 ... light source, 4 (B) ... blue light source (first light source), 4 (G) ... green light source (second light source), 4 (R) ... red light source ( (Third light source), 5 ... case, 6 ... light-shielding member, 30 ... emitting surface, 31 ... first side surface, 32 ... second side surface, 33 ... third side surface, 34 ... fourth side surface, 35, 36 ... end surface, 37 ... light scattering pattern, 38 ... prism formation region, 50 ... opening, 51 ... first side plate, 52 ... second side plate, 53 ... third side plate, 54 ... fourth side plate, 55 ... first end plate , 56 ... second end plate part, 61 ... reflecting surface, 100 ... image reading device, 110 ... translucent cover, 120 ... carriage, 130 ... optical system, 131, 132, 133 ... mirror, 134 ... lens, 140 ... Sensor, 150 ... Frame, 160 ... Cover, 380 ... Projection, 381 ... First slope, 382 ... Second Surface, 383 ... top, L (B) ... blue light, L (G) ... green light, L (R) ... red light, M ... medium, X ... first direction, Y ... second direction, Z ... sub scanning Direction, θa: first angle, θb: second angle.

Claims (10)

A light guide having a plurality of side surfaces extending in a first direction;
A first light source disposed on one of the end surfaces intersecting the first direction of the light guide;
A light shielding member;
Have
The light guide is located at a position spaced apart in the direction along the first direction with respect to the one end surface between the first side surface and the second side surface adjacent to each other among the plurality of side surfaces. An exit surface for emitting the light incident on the light guide from is disposed,
The light guide includes a prism formation region in which a plurality of prism-shaped convex portions are arranged along the first direction in a region sandwiched between the one end surface and the emission surface,
Each of the plurality of prismatic convex portions includes a first slope and a second slope that are inclined in a direction intersecting the first side surface, respectively.
The line illumination device according to claim 1, wherein the light shielding member is disposed at a position facing the prism forming region such that a light scattering reflective surface faces the prism forming region. The line lighting device according to claim 1,
Of the first slope and the second slope, an angle formed by the first slope located on the one end surface side with the first side surface is smaller than an angle formed by the second slope with the first side surface. Line lighting device. The line illumination device according to claim 2,
A first angle formed by the first slope with the first side surface is 20 ° to 50 °;
The line illumination device according to claim 2, wherein a second angle formed by the second slope with the first side surface is 90 ° to 45 °. In the line illuminating device as described in any one of Claim 1 to 3,
A second light source is disposed on the one end surface at a position opposite to the first side surface along a second direction intersecting the first direction with respect to the first light source. Line lighting device. The line illumination device according to claim 4,
The line illumination device according to claim 1, wherein a third light source is disposed on the one end surface at a position opposite to the first side surface along the second direction with respect to the second light source. The line lighting device according to claim 5,
Any one of the first light source, the second light source, and the third light source is a blue light source that emits blue light, the other one is a green light source that emits green light, and the remaining one Is a red light source that emits red light. In the line illuminating device as described in any one of Claim 1-6,
The line lighting device according to claim 1, wherein a third side surface having a light scattering pattern is disposed at a position facing the first side surface. In the line illuminating device as described in any one of Claim 1-7,
A case for accommodating the light guide inside;
The case is provided with an opening at a position overlapping the emission surface,
The line illumination device, wherein the light shielding member is included in the case.   An image reading apparatus comprising: the line illumination device according to claim 1; and a sensor that detects reflected light of illumination light emitted from the line illumination device. The image reading apparatus according to claim 9.
An image reading apparatus comprising a reduction optical system that guides the reflected light to the sensor.