LIGHT-GUIDING DEVICE APPLICABLE TO VEHICLES

Abstract

 A light-guiding device includes a light-guiding body (10, 10a), a light-entrance portion (20), a front reflection portion (30), a middle reflection portion (40), and a rear reflection portion (60, 60', 60"). The light-entrance portion (20) is formed on the bottom surface (12) of the light-guiding body (10, 10a). The front reflection portion (30) is formed on the top surface (11) of the light-guiding body (10, 10a) and has a first reflection surface (R1) and a second reflection surface (R2). The middle reflection portion (40) has a third reflection surface (R3). The rear reflection portion (60, 60', 60") is formed on a lateral side of the light-guiding body (10, 10a) and has a fourth reflection surface (R4) and a fifth reflection surface (R5, R5', R5").

Description

1. Field of the Invention

[0001] The present disclosure relates to a light-guiding device; more particularly, to a light-guiding device applied to vehicle lighting, which diverges light emitted from a point source by using a plate-shaped light-guiding body and turns the diverged light rays into a bar-shaped light beam through multiple reflections.

2. Description of Related Art

[0002] As lighting technology advances, LEDs have been widely used in vehicle lighting, e.g. car headlights. Light guides are required to change the shapes of light beams, which are originally emitted from a point source and then guided to form various shapes. Therefore, there exist various types of light guides depending on what shape of light is required.

[0003] It is an issue in the art of light guide designing to generate bar-shaped light with fewer LED point sources. In addition, other challenges include utilizing the limited space of a vehicle for headlamp and tail light and to downsize headlamps and tail lights.

SUMMARY OF THE INVENTION

[0004] Accordingly, one of the objectives of the present disclosure is to provide a light-guiding device applicable to vehicles, which does not take up much space and can diverge LED point sources such that light emitted therefrom spreads at a broad angle and forms a desired shape.

[0005] To achieve the above described purpose, one embodiment of the present disclosure provides a light-guiding device applicable to vehicles. The light-guiding device includes: a light-guiding body, a light-entrance portion, a front reflection portion, a middle reflection portion and a rear reflection portion. The light-guiding body is plate-shaped and has a top surface, a bottom surface, and a light-emission surface located between the top surface and the bottom surface. The light-entrance portion is cup-shaped and formed on the bottom surface of the light guiding body. The front reflection portion is formed on the top surface of the light-guiding body corresponding to the light-entrance portion. The front reflection portion is a recess and has a first reflection surface and a second reflection surface, in which the first reflection surface is located between the second reflection surface and the light-emission surface. The middle reflection portion has a third reflection surface. The rear reflection portion is formed on a lateral side of the light-guiding body and away from the light-emission surface. The rear reflection portion has a fourth reflection surface and at least one fifth reflection surface, in which the front reflection portion is located between the rear reflection portion and the light-emission surface. The middle reflection portion is located between the front reflection portion and the rear reflection portion, and the third reflection surface is located between the second reflection surface and the fifth reflection surface and faces the fourth reflection surface. Light emitted from a light source enters the light-entrance portion and diverges, in which the first reflection surface reflects a portion of the light towards the light-emission surface so that the light is emitted out of the light-guiding body therefrom along a light-emission direction. The second reflection surface reflects another portion of the light away from the light-emission surface and towards the third reflection surface and the fourth reflection surface, in which a portion of the light reflected by the second reflection surface is reflected by the third reflection surface towards the fourth reflection surface and then reflected by the fourth reflection surface towards the light-emission surface, and then emitted out of the light-guiding body therefrom. Another portion of the light reflected by the second reflection surface is reflected by the fourth reflection surface towards the fifth reflection surface, and then reflected by the fifth reflection surface towards the light-emission surface, and emitted out of the light-guiding body therefrom.

[0006] The present disclosure has the following advantages: the light-guiding device of the present disclosure enables light emitted therein to spread at a broad angle in the following manner: one half of the light entering the light-entrance portion travels along a first path, in which light is reflected once and then is emitted out of the light-guiding device from the light-emission surface, and the other half of the light entering the light-entrance portion is reflected three times and then emitted out of the light-guiding body along a second path and a third path. The second half portion of the light, i.e. light traveling along the second path and the third path, is spread apart on both sides of the first half portion of the light, i.e. light traveling along the first path, so that light entering the light-guiding body spreads at a wide angle and is emitted from the light-emission surface as a bar-shaped light beam.

[0007] For the further understanding of the present disclosure, the following embodiments are provided along with illustrations to facilitate the disclosure of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 

Fig. 1 is a perspective view illustrating a light-guiding device applicable to vehicles according to a first embodiment of the present disclosure.

Fig. 2 is another perspective view illustrating the light-guiding device according to the first embodiment of the present disclosure.

Fig. 3 is a top view illustrating the light-guiding device according to the first embodiment of the present disclosure.

Fig. 3A is a partially enlarged view illustrating the area A in Fig. 3.

Fig. 4 is a sectional view of Fig. 3 along the line IV-IV in Fig. 3.

Fig. 5 is a bottom view illustrating the light-guiding device according to the first embodiment of the present disclosure.

Fig. 6 is a perspective view illustrating a light-guiding device applicable to vehicles according to a second embodiment of the present disclosure.

Fig. 7 is another perspective view illustrating the light-guiding device according to the second embodiment of the present disclosure.

Fig. 8 is a perspective view illustrating a light-guiding device applicable to vehicles according to a third embodiment of the present disclosure.

Fig. 9 is another perspective view illustrating the light-guiding device according to the third embodiment of the present disclosure.

Fig. 10 is a top view illustrating the light-guiding device according to the third embodiment of the present disclosure.

Fig. 10A a partially enlarged view illustrating the area A in Fig. 10 with some of the components being removed.

Fig. 10B is a partially enlarged view illustrating the area B in Fig. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The aforementioned illustrations and following detailed description are for the purpose of further explaining the scope of the present disclosure. Other objectives and advantages related to the present disclosure will be illustrated in the following description and appended drawings.

The First Embodiment

[0010] Referring to Figs. 1 and 2, the perspective views of the light-guiding device of the present disclosure from rear-bottom and rear top perspectives are shown. The present disclosure discloses a light-guiding device 1 applicable to vehicles (hereinafter referred to as light-guiding device 1). The light-guiding device 1 includes a light-guiding body 10, a plurality of light-entrance portions 20, a plurality of front reflection portions 30, a plurality of middle reflection portions 40, and a plurality of rear reflection portions 60. The numbers of the light-entrance portion 20, the front reflection portion 30, the middle reflection portion 40, and the rear reflection portion 60 correspond to each other. In other embodiments, the numbers of the light-entrance portion 20, the front reflection portion 30, the middle reflection portion 40, and the rear reflection portion 60 are one, and the light-entrance portion 20, the front reflection portion 30, the middle reflection portion 40, and the rear reflection portion 60 form a light-guiding structure. In the present embodiment, the light-guiding body 10 is formed of three light-guiding structures and made integrally of a transparent acrylic material; however, the present disclosure is not limited thereto. The light-guiding structure will be described below.

[0011] The light-guiding body 10 is plate-shaped and has a top surface 11, a bottom surface 12, and a light-emission surface 13 located between the top surface 11 and the bottom surface 12. The top surface 11 is approximately parallel to the bottom surface 12. The light-emission surface 13 has a plurality of serrated structures. With reference to Fig. 3, which shows a top view of the light-guiding device of the present disclosure, each of the serrated structures includes a front-facing surface perpendicular to a light-emission direction L and a side-facing surface parallel to the light-emission direction L. The front-facing surface is slightly convex in this embodiment. The light-emission direction L is the optical axis of a light source.

[0012] With reference to Fig. 1, the light-entrance portion 20 is formed on the bottom surface of the bottom surface 12 and is cup-shaped, or to say a cup-shaped optical structure. The light source S is disposed at the bottom of the light-entrance portion 20. Referring to Fig. 4, in the present embodiment, light emitted from the light source S enters the light-entrance portion 20 and diverges.

[0013] Referring to Fig. 3, the front reflection portion 30 opposite the light-entrance portion 20 is formed on the top surface 11 of the light-guiding body 10. The front reflection portion 30 is a recess having a first reflection surface R1 and a second reflection surface R2. The first reflection surface R1 is located between the second reflection surface R2 and the light-emission surface 13. The first reflection surface R1 and the second reflection surface R2 are slightly convex. More specifically, the first reflection surface R1 and the second reflection surface R2 protrude towards the top surface 11 and reflect light through reflections, in which the first reflection surface R1 faces the light-emission surface 13, and the second reflection surface R2 faces the opposite side from the first reflection surface R1.

[0014] With reference to Fig. 3, the first reflection surface R1 and the second reflection surface R2 are symmetric and convex, in which the first reflection surface R1 is connected to the second reflection surface R2, and the position where the first reflection surface R1 and the second reflection surface R2 connect together forms a turning line 31, which passes through the center of the light-entrance portion 20 and is roughly perpendicular to the light-emission direction L. The width of the light-entrance portion 20 is approximately equal to that of the front reflection portion 30. Furthermore, the position of the center of the light-entrance portion 20 corresponds to the turning line 31 of the front reflection portion 30. Light emitted from the light source S is distributed evenly to the first reflection surface R1 and the second reflection surface R2, in which the first reflection surface R1 reflects a portion of the light forwards and the second reflection surface R2 reflects the other portion of the light backwards.

[0015] The middle reflection portion 40 includes a third reflection surface R3. The third reflection surface R3 can be a flat surface or a curved surface. The middle reflection portion 40 is located between the second reflection surface R2 and the rear reflection portion 60 and reflects light to the rear reflection portion 60. The middle reflection portion 40 of the present embodiment is hollow and passes through the light-guiding body 10. The third reflection surface R3 is an inner surface of the middle reflection portion 40 and faces the front reflection portion 30. The middle reflection portion 40 of the present embodiment is trapezoid-shaped; however, the present disclosure is not limited thereto. For example, the middle reflection portion 40 can be rectangular or semi-circular in other embodiments.

[0016] With reference to Fig. 5, a projected length Wx3 of the third reflection surface R3 parallel to the light-emission direction L is equal to one half of a projected length D30 of the front reflection portion 30 parallel to the light-emission direction. In other words, a half of the light reflected backwards by the front reflection portion 30, that is to say, a half of the light reflected by the second reflection surface R2, is reflected by the third reflection surface R3 to be perpendicular to the light-emission direction L. In other words, the included angle between the third reflection surface R3 and the light-emission direction L is approximately 45 degrees.

[0017] The rear reflection portion 60 is formed on a lateral side of the light-guiding body 10 and away from the light-emission surface 13. The front reflection portion 30 is located between the rear reflection portion 60 and the light-emission surface 13. The rear reflection portion 60 is formed on the rear edge of the light-guiding body 10 and has a fourth reflection surface R4 and a fifth reflection surface R5, that is to say, the fourth reflection surface R4 and the fifth reflection surface R5 form the rear end surface 14 of the light-guiding body 10 and connect the top surface 11 with the bottom surface 12. In this way, the surface area of the light-guiding body 10 is saved. However, the present disclosure is not limited thereto. The rear reflection portion 60 can provide the fourth reflection surface R4 and the fifth reflection surface R5 by passing through the light-guiding body 10, similar to the way the middle reflection portion 40 provides the third reflection surface R3. Preferably, the fourth reflection surface R4 and the fifth reflection surface R5 are located on both sides of the third reflection surface R3 about the light-emission direction L, which is to say the third reflection surface R3, the fourth reflection surface R4 and the fifth reflection surface R5 do not overlap in the light-emission direction L.

[0018] In the present embodiment, the middle reflection portion 40 is located between the front reflection portion 30 and the rear reflection portion 60. The third reflection surface R3 is located between the second reflection surface R2 and the fifth reflection surface R5 and opposite the fourth reflection surface R4. More specifically, the fifth reflection surface R5 is approximately parallel to the third reflection surface R3, which is approximately perpendicular to the fourth reflection surface R4. The included angle between fourth reflection surface R4 and the light-emission direction L is approximately 45 degrees. In this manner, light reflected by the third reflection surface R3 towards the fourth reflection surface R4 will be reflected by the fourth reflection surface R4 towards the light-emission surface 13, where the light is emitted out of the light-guiding body 10 along the light-emission direction L.

[0019] Another half of the light reflected backwards by the front reflection portion 30, that is, light reflected by the second reflection surface R2, is reflected by the fourth reflection surface R4 towards the fifth reflection surface R5 in a direction perpendicular to the light-emission direction L, and then reflected by the fifth reflection surface R5 towards the light-emission surface 13 along the light-emission direction L and then emitted out of the light-guiding body 10 therefrom.

[0020] In summary, the light-guiding device provided by the present disclosure spreads light emitted from the light source S into three portions, which are projected to the light-emission surface 13 along three different paths. Light emitted from the light source S enters the light-entrance portion 20 and diverges to the first reflection surface R1 and the second reflection surface R2. The portion of light traveling along the first path is reflected by the first reflection surface R1 towards the light-emission surface 13 along the light-emission direction L. The portion of light traveling along the second path is reflected by the second reflection surface R2 away from the light-emission surface 13 and towards the third reflection surface R3, where it is reflected again towards the fourth reflection surface R4 and then reflected by the fourth reflection surface R4 towards the light-emission surface 13, and then is emitted out of the light-guiding body 10 therefrom. More specifically, the third reflection surface R3 reflects approximately one half of the light coming from the second reflection surface R2 towards the fourth reflection surface R4, which is then reflected by the fourth reflection surface R4 towards the light-emission surface 13 and then emitted out of the light-guiding body 10. The portion of light traveling along the third path is reflected by the second reflection surface R2 away from the light-emission surface 13 and towards the fourth reflection surface R4, and then reflected by the fourth reflection surface R4 and the fifth reflection surface R5 respectively, and finally travels out of the light-guiding body 10 from the light-emission surface 13.

[0021] Approximately one half of light emitted from the light source S is emitted out of the light-guiding device 1 from the light-emission surface 13 along the first path, and the other half of light emitted from the light source S travels along the second path and the third path respectively, in which light is reflected three times and emitted out of the light-guiding device 1 from the light-emission surface 13. The second path and the third path are respectively located on both sides of the first path so that light is emitted out of the light-guiding device 1 from the light-emission surface 13 at a wide angle.

[0022] Referring to Fig. 5, the light-entrance portion 20 of the present embodiment defines a longitudinal center line Y parallel to the light-emission direction L and a latitudinal center line X. The third reflection surface R3 and the fifth reflection surface R5 are located on both sides of the longitudinal center line Y respectively. Moreover, the length of the fourth reflection surface R4 is larger than that of the third reflection surface R3 and that of the fifth reflection surface R5.

[0023] The projection of the fifth reflection surface R5 that is perpendicular to the light-emission direction L does not overlap that of the front reflection portion 30 and the middle reflection portion 40. By this structural manner, light reflected by the fifth reflection surface R5 to travel along the light-emission direction L will not be blocked by the front reflection portion 30 and the middle reflection portion 40.

[0024] The projection of the third reflection surface R3 that is parallel to the light-emission direction L does not overlap that of the fifth reflection surface R5. In this structural manner, light reflected by the fourth reflection surface R4 towards the fifth reflection surface R5 will not be blocked by the third reflection surface R3. Furthermore, a projected length Wy4 of the fourth reflection surface R4 that is parallel to the light-emission direction L is equal to or larger than the sum of the projected length of the third reflection surface R3 and that of the fifth reflection surface R5 (Wy3 + Wy5).

[0025] With reference to Figs. 3 and 3A, the light-guiding device 1 of the present embodiment has three light-guiding structures that are adjacent to each other. The rear reflection portion 60 of the light-guiding structure on the right side is connected to that in the middle. A fixing portion is disposed between the light-guiding structure in the middle and the one on the left hand side such that a part of the rear reflection portion 60 is hidden. More specifically, the fourth reflection surface R4 of the rear reflection portion 60 of the light-guiding structure in the middle is connected to the fifth reflection surface R5 of the rear reflection portion 60 on the left hand side, as shown in Fig. 5. As shown in Fig. 3, the fifth reflection surface R5 is connected to the fourth reflection surface R4 of the adjacent light-guiding structure through a connecting surface 16. The included angle between the connecting surface 16 and the light-emission direction L is approximately 12 degrees.

The Second Embodiment

[0026] Figs. 6 and 7 illustrate the light-guiding device 1a applicable to vehicles according to the second embodiment of the present disclosure. With reference to Figs. 6 and 7, the difference between the present embodiment and the previous embodiment is that the number of the light-guiding structures in this embodiment is one, and the light-guiding structure is formed on a light-guiding body 10a that has an elongated shape. The light-guiding structure includes a light-entrance portion 20, a front reflection portion 30, a middle reflection portion 40, and a rear reflection portion 60. The light-guiding body 10a has a top surface 11, a bottom surface 12, and a light-emission surface 13. The front reflection portion 30 includes a first reflection surface R1 and a second reflection surface R2, the middle reflection portion 40 includes a third reflection surface R3, and the rear reflection portion 60 includes a fourth reflection surface R4 and a fifth reflection surface R5.

The Third Embodiment

[0027] With reference to Figs. 8 to 10, the present embodiment is similar to the first embodiment in a way that the light-guiding body also includes three light-guiding structures, and the difference therebetween is that the rear reflection portions (60', 60") include at least one serrated fifth reflection surface (R5', R5"). Apart from the fifth reflection surface, the present embodiment and the first embodiment share the same structural features. Each of the fifth reflection surfaces (R5', R5") includes a plurality of serrated protrusions, each of which has an L-shaped edge and includes a micro reflection surface and a micro extension surface connected to the micro reflection surface. The included angle between the micro reflection surface and the micro extension surface is larger than 90 degrees. The present embodiment provides the advantage that the size of the light-guiding device, especially the dimension perpendicular to the light-emission direction, is enlarged. In this way, the width of each of the light-guiding structures is increased. That is to say, the width of the light-guiding device 1b of the present embodiment is larger than that of the light-guiding device 1 of the first embodiment.

[0028] Referring to Fig. 10A, which shows the light-guiding structure on the left side in the Fig. 10, the fifth reflection surface R5' of the light-guiding structure has a plurality of serrated protrusions, each of which has a micro reflection surface R51 and a micro extension surface R52 connected to the micro reflection surface R51 at an angle. More specifically, each micro reflection surface R51 is roughly parallel to the third reflection surface R3 and reflects light coming from the fourth reflection surface R4 towards the light-emission surface 13 along the light-emission direction L. The micro extension surface R52 is parallel to light reflected by the fourth reflection surface R4 towards the fifth reflection surface R5' and perpendicular to the light-emission direction L. Moreover, the micro extension surface R52 is connected between two adjacent micro reflection surfaces R51 and acts as a spacer therebetween. Furthermore, the length of the micro extension surface R52 is smaller than that of the micro reflection surface R51. In this way, the fifth reflection surface R5' provides a function that is similar to the function of the fifth reflection surface R5 in the first embodiment, in which the plurality of micro reflection surfaces R51 reflect light towards the light-emission surface 13 along the light-emission direction L, and the plurality of micro extension surfaces R52 enlarge the overall width of the fifth reflection surface R5'.

[0029] Referring to Fig. 10B, which illustrates the fifth reflection surface R5" on the right side of Fig. 10, the fifth reflection surface R5" has a plurality of serrated protrusions, each of which has a micro reflection surface R53 and a micro extension surface R54 connected to the micro reflection surface R53 at an angle. As is the case with the fifth reflection surface R5' on the left side, each of the micro reflection surfaces R53 is approximately parallel to the third reflection surface R3 and reflects light towards the light-emission surface 13 along the light-emission direction L. The included angle between the micro reflection surface R53 and the light-emission direction L is 45 degrees. The micro extension surface R54 is parallel to light reflected towards the fifth reflection surface R5" and perpendicular to the light-emission direction L. Each micro extension surface R54 is connected between two adjacent micro reflection surfaces R53 and acts as a spacer therebetween. The length of the micro extension surface R54 is approximately equal to that of the micro reflection surface R51.

[0030] Furthermore, as in the first embodiment, the fourth reflection surface R4 and the fifth reflection surface R5 of each light-guiding structure are respectively situated on both sides of the third reflection surface R3 with respect to the light-emission direction L, that is to say, the third reflection surface R3, the fourth reflection surface R4 and the fifth reflection surface R5 do not overlap in the light-emission direction L. Moreover, the projected length of the fourth reflection surface R4 that is parallel to the light-emission direction L is equal to or larger than the sum of the projected length of the third reflection surface R3 parallel to the light-emission direction L and that of the fifth reflection surface (R5' or R5").

[0031] In summary, the present disclosure is advantageous in that the light-guiding device provided by the present disclosure diverges light emitted from a point source so that the light spreads at a wide angle. One half of the light entering the light guiding device travels along the first path, in which the light is reflected once and emitted out of the light-guiding device 1 from the light-emission surface 13. Another half of the light entering the light-entrance portion 20 is distributed into two portions, each of which travels along the second path and the third path on both sides of the light-entrance portion 20 respectively and then is emitted out of the light-guiding device 1. By the above technical manner, light is spread at a wide angle and emitted from the light-emission surface 13 as a bar-shaped light beam.

[0032] It should be noted that terms such as "roughly" or "approximately" used in this specification are for the purpose of describing minor deviations caused by tolerances, processing errors, etc. These minor deviations do not change the spirit of the present disclosure.

[0033] The description illustrated supra set forth simply the preferred embodiments of the present disclosure; however, the characteristics of the present disclosure are by no means restricted thereto. All changes, alterations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the present disclosure delineated by the following claims.

Claims

1. A light guiding device (1, 1a, 1b) applicable to vehicles, comprising:

a light-guiding body (10, 10a) being plate-shaped and having a top surface (11), a bottom surface (12), and a light-emission surface (13) located between the top surface (11) and the bottom surface (12);

a light-entrance portion (20) being cup-shaped and formed on the bottom surface (12) of the light guiding body (10, 10a);

a front reflection portion (30) formed on the top surface (11) of the light-guiding body (10, 10a) corresponding to the light-entrance portion (20), the front reflection portion (30) being a recess and having a first reflection surface (R1 and a second reflection surface (R2), in which the first reflection surface (R1 is located between the second reflection surface (R2) and the light-emission surface (13);

a middle reflection portion (40) having a third reflection surface (R3);

a rear reflection portion (30) formed on a lateral side of the light-guiding body (10, 10a) and away from the light-emission surface (13), in which the rear reflection portion (60, 60', 60") has a fourth reflection surface (R4) and at least one fifth reflection surface (R5), wherein the front reflection portion (30) is located between the rear reflection portion (60, 60', 60") and the light-emission surface (13),

wherein the middle reflection portion (40) is located between the front reflection portion (30) and the rear reflection portion (60, 60', 60"), and the third reflection surface (R3) is located between the second reflection surface (R2) and the fifth reflection surface (R5, R5', R5") and faces the fourth reflection surface (R4),

and wherein light emitted from a light source (S) enters the light-entrance portion (20) and diverges, in which the first reflection surface (R1 reflects a portion of the light towards the light-emission surface (13) so that the light is emitted out of the light-guiding body (10, 10a) from the light-emission surface (13) along a light-emission direction, and the second reflection surface (R2) reflects another portion of the light away from the light-emission surface (13) and towards the third reflection surface (R3) and the fourth reflection surface (R4), wherein a portion of the light reflected by the second reflection surface (R2) is reflected by the third reflection surface (R3) towards the fourth reflection surface (R4) and then reflected by the fourth reflection surface (R4) towards the light-emission surface (13), and then emitted out of the light-guiding body (10, 10a) therefrom, and wherein another portion of the light reflected by the second reflection surface (R2) is reflected by the fourth reflection surface (R4) towards the fifth reflection surface (R5, R5', R5"), and then reflected by the fifth reflection surface (R5, R5', R5") towards the light-emission surface (13), and emitted out of the light-guiding body (10, 10a) therefrom.

2. The light-guiding device according to claim 1, wherein the first reflection surface (R1 and the second reflection surface (R2) are arc-shaped and symmetric to each other, and wherein the first reflection surface (R1 and the second reflection surface (R2) are connected to each other at a turning line (31), which passes through the center of the light-entrance portion (20) and is roughly perpendicular to the light-emission direction (L).

3. The light-guiding device according to claim 1, wherein the middle reflection portion (40) is hollow and passes through the light-guiding body (10, 10a), the third reflection surface (R3) being an inner surface of the middle reflection portion (40) and facing the front reflection portion (30).

4. The light-guiding device according to claim 1, wherein a projection length Wx3 of the third reflection surface (R3) is equal to one half of a projected length D30 of the front reflection portion (30), in which the projected length Wx3 of the third reflection surface (R3) and that of the front reflection portion (30) are perpendicular to the light-emission direction (L).

5. The light-guiding device according to claim 1, wherein the fourth reflection surface (R4) and the fifth reflection surface (R5, R5', R5") are located on both sides of the third reflection surface (R3) about the light-emission direction (L), in which the third reflection surface (R3), the fourth reflection surface (R4) and the fifth reflection surface (R5, R5', R5") do not overlap in the light-emission direction (L).

6. The light-guiding device according to claim 1, wherein the light-entrance portion (20) defines a center line (Y) parallel to the light-guiding body (10, 10a) and the light-emission direction (L), the third reflection surface (R3) and the fifth reflection surface (R5, R5', R5") being located on both sides of the center line (Y).

7. The light-guiding device according to claim 1, wherein the length of the fourth reflection surface (R4) is larger than that of the third reflection surface (R3) and that of the fifth reflection surface (R5, R5', R5").

8. The light-guiding device according to claim 1, wherein a projection of the fifth reflection surface (R5, R5', R5") that is perpendicular to the light-emission direction (L) does not overlap the front reflection portion (30) and the middle reflection portion (40) in the light-emission direction (L).

9. The light-guiding device according to claim 1, wherein a projection of the third reflection surface (R3) that is parallel to the light-emission direction (L) does not overlap the fifth reflection surface (R5, R5', R5").

10. The light-guiding device according to claim 1, wherein a projected length Wy4 of the fourth reflection surface (R4) that is parallel to the light-emission direction (L) is equal to or larger than the sum of a projected length Wy3 of the third reflection surface (R3) and a projected length Wy5 of the fifth reflection surface (R5, R5', R5") that are parallel to the light-emission direction (L).

11. The light-guiding device according to claim 1, wherein at least one of the at least one fifth reflection surface (R5, R5', R5") is a serrated surface having a plurality of serrated protrusions, each of which has a micro reflection surface (R51, R53) and a micro extension surface (R52, R54) connected to the micro reflection surface (R51, R53) at an angle, and wherein the micro reflection surface (R51, R53) is parallel to the third reflection surface (R3) such that the micro reflection surface (R51, R53) reflects a portion of light coming from the fourth reflection surface (R4) towards the light-emission surface (13) along the light-emission direction (L), where the portion of light is emitted out of the light-guiding body (10, 10a).

Drawing