Light emitting device and road surface marking device

Abstract

To make it possible to emit light more intensely when emitting light to a particular direction including a small elevation angle by using refraction.SOLUTION: A light emitting device 10 comprises a transparent material 12 and a light source 14. The transparent material 12 is a square column with a bottom surface considered as a parallelogram, and a lateral surface of the square column is a top surface 12a of the light emitting device 10 and a road surface 21. Light from the light source 14 is entered to an incident part 16, and is entered to the top surface 12a after reflecting at a reflection board 18 of a right lateral surface 12d. A part of incident light 22 is refracted to be refraction light 23 of a large refraction angle direction, and reflection light 24 being residual light is reflected at the transparent material 12 by the reflection board 18, is entered as incident light 22a to the top surface 12a again at same incident angle at the first time, and is emitted with same refraction angle of the refraction light 23. Similarly, reflection light at the top surface 12a is entered as incident light to the top surface 12a repeatedly.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a light-emitting device and a road marking device, and in particular to light-emitting device that utilizes refracted light. [Background technology]

[0002] Conventionally, light-emitting diodes have been embedded in the center lines of roads, at intersections, or near pedestrian crossings, and are illuminated at night to guide and alert drivers and pedestrians.

[0003] For example, Patent Document 1 proposes a light irradiation device that can irradiate at a small elevation angle by arranging a resin with a right-angled triangular cross section so that the hypotenuse is underground, the long side is the road surface, and the short side is perpendicular to the road surface, and by making light incident from the short side in a direction parallel to the road surface. More specifically, when light is incident from the short side in a direction parallel to the road surface, the incident light decreases in incidence angle as it is repeatedly reflected by the hypotenuse face and the road surface, and when the incidence angle on the road surface becomes equal to or smaller than the critical angle, part of the light is refracted in a direction closer to the road surface (with a large refraction angle). In other words, light can be emitted at a small elevation angle.

[0004] When light-emitting road studs are placed on the road surface, pedestrians may trip over the road studs and vehicles may rattle every time they run over a road stud. However, in Patent Documents 1 and 2, the light-emitting device can emit light without having to protrude from the road surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3982174 specification [Patent Document 2] Patent No. 2857974 specification Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, light that is incident on the road surface and is reflected without being refracted is reflected by a surface that corresponds to the hypotenuse of a right-angled triangle in a vertical cross section, thereby being made to re-enter the road surface.

[0007] However, the angle of incidence of the re-entered light is smaller than the initial angle of incidence, so the refraction angle is also smaller. In this case, the number of refractions is small at a large refraction angle. When the refraction angle is large, a large proportion of the light is reflected without being refracted, and as a result, the refracted light in the direction of the large refraction angle is weaker. If the angle of incidence is increased to accommodate small elevation angles, it may be possible to increase the refraction angle. However, as the refraction angle increases, more light is reflected without being refracted. In other words, in a structure that uses refraction to emit light, increasing the refraction angle will increase the amount of reflected light without being refracted, resulting in weaker emitted light.

[0008] An object of the present invention is to enable stronger light emission when light is emitted in a specific direction including a small elevation angle by utilizing refraction. [Means for solving the problem]

[0009] The light emitting device according to the present invention comprises a light source means and a three-dimensional light guide formed of a first medium made of a transparent solid or liquid, the light guide having a boundary surface with a second medium having a refractive index relatively smaller than that of the first medium and an incident portion into which light from the light source means is incident, the light guide having a surface on which the boundary surface and the incident portion are provided and portions other than the incident portion covered with a reflective material, the light guide being characterized in that the light from the light source means passing through the incident portion is incident on the boundary surface at a predetermined incident angle corresponding to the relative refractive index of the first medium with respect to the second medium, thereby radiating the refracted light at the boundary surface at a refraction angle at which it reaches a predetermined target position, and the light reflected at the boundary surface is reflected inside the light guide by the reflective material to become incident light that is incident on the boundary surface at the predetermined incident angle, thereby radiating the refracted light of the incident light at the boundary surface at a refraction angle at which it reaches the predetermined target position.

[0010] The boundary surface may also form part of a planar surface of an object when the light guide is embedded in the object.

[0011] The light guide is formed as a prism having a parallelogram-shaped bottom surface, and one of the side surfaces of the prism is the boundary surface.

[0012] The ratio of the base side corresponding to the boundary surface to the height of the parallelogram is set according to the relative refractive index of the first medium with respect to the second medium.

[0013] The light source means is disposed so as to suppress reflection of light irradiated toward the incident portion.

[0014] A road marking device according to the present invention includes the above-described light-emitting device, and is installed so that the boundary surface forms a part of the road surface. Effect of the Invention

[0015] According to the invention recited in claim 1, when light is emitted in a specific direction including a small elevation angle by utilizing refraction, it is possible to emit light more intensely.

[0016] According to the invention as set forth in claims 2 and 3, the second medium can be provided without protruding from the boundary surface with the second medium.

[0017] According to the invention as recited in claim 4, it is possible to increase the number of times that light is emitted from the boundary surface with the second medium.

[0018] According to the invention as set forth in claim 5, the light from the light source can be efficiently incident on the light guide.

[0019] According to the invention as set forth in claim 6, it is possible to emit strong light at a small elevation angle from the road surface. [Brief description of the drawings]

[0020] [Figure 1]1A is a schematic diagram showing an embodiment of a light emitting device according to the present invention, in which (a) is a top view of the light emitting device 10, (b) is a front view of the light emitting device 10, and (c) is a right side view of the light emitting device 10. FIG. [Diagram 2] 1 is a diagram for explaining refracted light and reflected light at a boundary surface between different media. [Diagram 3] FIG. 2 is a graph showing the relationship between the refraction angle and the transmittance of p-waves and s-waves. [Figure 4] 1 is a vertical cross-sectional view of a light emitting device according to an embodiment of the present invention. [Diagram 5] 5 is a vertical cross-sectional view of the light guide shown in FIG. [Figure 6] 11A and 11B are diagrams showing optical paths when a light guide having a sufficiently long base relative to its height is used in the present embodiment. [Figure 7] 10A and 10B are diagrams for explaining a method for setting the angle of an acute vertex of a parallelogram in the vertical cross section of a light guide in the present embodiment. [Figure 8] 13A and 13B are diagrams for explaining another method for setting the angle of the acute vertex of the parallelogram of the vertical cross section of the light guide in the present embodiment. [Figure 9] 10A and 10B are diagrams for explaining the conditions under which incidence onto the upper surface at the same incidence angle ends in the present embodiment. [Figure 10] 11A and 11B are diagrams for explaining the setting of the ratio between the base and the height of a parallelogram in the vertical cross section of a light guide in the present embodiment. [Figure 11] 11A and 11B are diagrams showing the results of a simulation when a light source a is used in the present embodiment. [Figure 12] 13A and 13B are diagrams illustrating the results of a simulation when a light source b is used in the present embodiment. [Figure 13] 13A to 13C are diagrams showing the results of a simulation when a light source c is used in the present embodiment. [Figure 14] FIG. 11 is a graph showing the relationship between the distance from the light guide to the driver and the light intensity received by the driver's eyes from a road marking, calculated according to a first calculation condition in the present embodiment. [Figure 15] In this embodiment, it is a diagram showing, in a graph format, the relationship between the distance from the light guide to the driver obtained according to the second calculation condition and the light intensity received by the driver's eyes from the road marking. [Figure 16] In this embodiment, it is a diagram showing, in a graph format, the relationship between the distance from the light guide to the driver obtained according to the third calculation condition and the light intensity received by the driver's eyes from the road marking. [Figure 17] It is a diagram showing an example of the structure of the road marking device in this embodiment. [Figure 18] It is a diagram showing another example of the structure of the road marking device in this embodiment. [Figure 19] It is a diagram showing another example of the structure of the road marking device in this embodiment. [Figure 20] It is a diagram showing an example of the road surface light-emitting unit in this embodiment, where (a) is a top view, (b) is a front view, and (c) is a bottom view. [Figure 21] It is a diagram showing another example of the road surface light-emitting unit in this embodiment, where (a) is a top view, (b) is a front view, and (c) is a bottom view. [Figure 22] It is a diagram for explaining a method of embedding the road marking device in this embodiment in a road. [Diagram 23] It is a diagram showing an example of the structure of the road slab in this embodiment, where (a) is a top view, (b) is a side cross-sectional view when cut along the line A-A' shown in (a) and (c), and (c) is a bottom view.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0022] <Structure of the Light-Emitting Device> Fig. 1 is a schematic diagram showing an embodiment of a light emitting device according to the present invention. In Fig. 1, (a) is a top view of a light emitting device 10 in this embodiment, (b) is a front view of the light emitting device 10, and (c) is a right side view of the light emitting device 10. The light emitting device 10 in this embodiment includes a light guide 12 and a light source 14.

[0023] The light guide 12 in this embodiment is formed into a three-dimensional shape by a first medium made of a transparent solid or liquid. More specifically, as shown in Fig. 1(b), the light guide 12 is formed as a quadrangular prism with a parallelogram-shaped bottom surface (front surface in Fig. 1(b)). In the following description, although not shown, the surface opposite to the top surface shown in Fig. 1(a) (the downward direction in Fig. 1(b)) will be referred to as the "bottom surface".

[0024] In this embodiment, the light guide 12 is in a prismatic shape with a parallelogram at its bottom surface, and is used in an inverted manner. Therefore, even though the shape of the top surface of the square prism is a parallelogram, one of the side surfaces of the square prism, which is rectangular, corresponds to the "top surface" when used as the light emitting device 10.

[0025] When the light emitting device 10 in this embodiment is used as a road marking device described later, the light guide 12 is embedded in the road. In this case, the upper surface of the light guide 12 forms part of the planar road surface. The upper surface of the light guide 12 also becomes the boundary surface with air as a second medium present on the road. Therefore, in the following description, the "upper surface", which is one of the side surfaces of the light guide 12, and the "boundary surface" with the second medium are used synonymously. Air is a medium with a relatively smaller refractive index than the first medium that forms the light guide 12.

[0026] In addition, when the light-emitting device 10 in the present embodiment is applied to a road marking device, the second medium is basically air. In the present embodiment, it is sufficient that the light from the light source 14 is refracted at the interface with the second medium and emitted from the light-emitting device 10. That is, the second medium does not necessarily have to be limited to air as long as it is a medium with a relatively small refractive index compared to the first medium. For example, a vacuum or the like may be used. However, in the present embodiment, since the case where the light-emitting device 10 is applied to a road marking device is assumed for explanation, unless otherwise specified, "air" is used synonymously with the second medium.

[0027] The light source 14 provided as the light source means in the present embodiment is installed near the acute angle of the bottom surface of the light guide 12 and emits light toward the light guide 12. Incidentally, although the light source means is illustrated as one light source 14 in FIG. 1, the light source 14 may be composed of a light source group including a plurality of light sources. In this case, the plurality of light sources are arranged side by side in the thickness direction of the light guide 12 (the vertical direction in the drawing in FIG. 1(a), the horizontal direction in the drawing in FIG. 1(c)). The incident portion 16 in the present embodiment is provided near the acute angle of the bottom surface of the light guide 12 facing the interface with the second medium as shown in FIG. 1 and at a position slightly away from the angle, but it is not necessarily provided away from the angle.

[0028] A slit-shaped incident portion 16 is provided in the portion of the light guide 12 facing the light source 14 so that the light from the light source 14 is incident into the light guide 12. The incident portion 16 may be formed and arranged in an appropriate shape according to the arrangement and size of the light source 14, the direction of the light emitted from the light source 14, and the number of light sources 14 constituting the light source means.

[0029] Then, on the interface of the light guide 12 with the second medium and the surface where the incident portion 16 is provided, the portion other than the incident portion 16 is covered with a reflecting plate 18 as a reflecting material. The reflecting plate 18 is illustrated by a thick line in FIG. 1. The reflecting plate 18 may be formed on the surface of the light guide 12 by metal vapor deposition or the like. All the light incident on the surface of the reflecting plate 18 within the light guide 12 is reflected.

[0030] In this embodiment, it is assumed that the reflector 18 is provided on the outer surface of the light guide 12, but this is not necessary. For example, if a member surrounding the light guide 12 provides the same function as a reflector when the light emitting device 10 is installed in a predetermined location, it is not necessary to provide a reflector directly on the light guide 12. For example, a reflector may be provided on the inner surface of a housing that houses the light emitting device 10, and the light guide 12 may be housed therein. Of course, no reflector is provided on the boundary surface and the portion corresponding to the incident portion 16.

[0031] <Refraction and reflection of light incident on a boundary surface> The basic principle of when light incident on the boundary surface of a medium is refracted and emitted and when it is reflected will be described with reference to Fig. 2. Here, a specific example will be given assuming that the light emitting device 10 of the present embodiment is applied to a road marking device.

[0032] As an example of a case where refraction is used to emit light in a specific direction including a small elevation angle, when light is emitted from the road surface toward the driver of a vehicle approaching a road marking point, in order for the driver to see the light, it is necessary to emit light toward the driver's eye height, which is the target position of the light, that is, at a very small elevation angle from the road marking point. In this embodiment, the height from the ground and the distance from the road marking point are used as information indicating the specified target position to which the light is to be delivered. Here, when the height of the driver's eyes is H [m] and the distance from the road marking point to the driver is L [m], the elevation angle θ E Between the two tan θ E =H / L (1) For example, when L=30m and H=1.5m, θ E teeth, tan θ E =1.5 / 30 (2) θ E =arctan(1.5 / 30) =2.86° Small elevation angle θ EAs a method of emitting light from the road surface, it is not realistic to dig a groove in the road surface to allow light to pass through, place a light source in the groove, and emit light from the light source at a small elevation angle. For example, if a light source with a size H = 1.5 cm is placed in the groove, the θ E If light is to be emitted at 1000 nm, the required groove length L is 30 cm, which is very long, according to an equation equivalent to equation (2). If part of the groove becomes filled with dirt and dust over time, the light will no longer be emitted to the ground.

[0033] Small elevation angle θ E Another method of emitting light at a low temperature is to use the refraction of light. As shown in Fig. 2, a transparent solid container filled with a transparent solid such as glass or a transparent liquid such as water is used as a light guide 12, and the light guide 12 is buried in a road so that one side of the light guide 12, specifically the upper side of the light guide 12, is the road surface 21. When light 22 is obliquely incident on the road surface 21 from the light guide 12 side, it is refracted by the road surface 21 and is emitted at a small elevation angle θ E 2, the dotted lines indicate the optical paths, and the dashed lines indicate auxiliary lines that indicate the direction perpendicular to the road surface 21. The same applies to the following figures. In this case, the incident angle θ I , refraction angle θ T (=90°-θ E ) and the refractive index n of the light guide, n=sinθ T / sinθ I (3) For example, when Pyrex glass is used for the light guide 12 having a refractive index n=1.47, the elevation angle θ calculated by the formula (2) is E = 2.86°, i.e., the refraction angle θ T To emit light at =87.14°, from equation (3), sinθ I =sinθ T / n ···(4) =sin(87.14°) / 1.47 =0.679 θ I =arcsin0.679 =42.80° That is, in this embodiment, the incident light 22 corresponding to the light from the light source 14 is incident at a predetermined angle of incidence θ corresponding to a refractive index (more specifically, the relative refractive index of the material of the light guide 12 with respect to air) n and a predetermined target position (here, the height of the driver's eyes) where the emitted light 23 is to reach. I By making the light incident on the road surface 21, the light can be irradiated to the driver.

[0034] The road marking uses refracted light and is directed at the driver of the vehicle heading towards the road marking point at a very small elevation angle θ E In other words, a large refraction angle θ T When the light 23 is irradiated from the road surface 21, the intensity of the light 23 received by the driver is weakened by two factors in addition to the long distance to the road marking. The two factors are that the light spreads due to refraction, and that the proportion of the light 22 that is refracted out of the light 22 that is incident on the road surface 21 from the light guide 12 side is small. The former can be exemplified as follows. From formula (3), θ T =arcsin(n sinθ I ) ···(5) For example, the incidence angle θ that satisfies equation (4) I Refraction angle θ at ±0.05° of 42.80° T From equation (5), it is 86.23°(θ I =42.80°-0.05°) and 88.64°(θ I = 42.80° + 0.05°). Therefore, when light with an illumination angle of ±0.05°, i.e., 0.1°, is incident at an angle of θ I When the light is incident on the road surface 21 at an angle of 42.75° to 42.85°, the refracted light 23 is T The irradiation angle is 2.41°, from 86.23° to 88.64°, and the light 23 is expanded by about 24 times or more due to refraction. In order to irradiate the refracted light 23 with a small irradiation angle to the driver of the vehicle heading towards the road marking point, a light source with a very small irradiation angle (for example, 0.1° or less) may be used.

[0035] The latter point where the ratio of the refracted light 22 incident on the road surface 21 from the light guide 12 is small can be determined as follows. When the light 22 is refracted at a boundary surface such as the above-mentioned road surface 21, a part of the light 24 is reflected at the boundary surface. The refraction angle θ T When the angle is close to 90°, the ratio of reflected light 24 is high and the ratio of refracted light 23 is low. The ratio of the two can be calculated by the Fresnel formula shown below.

[0036] Incidentally, light can be divided into p-waves and s-waves. In the case of FIG. 2, the component of light 22 parallel to the plane of the drawing is a p-wave, and the component perpendicular to the plane of the drawing is an s-wave. In this explanation, "refractive index" is written as "transmission." The amplitude transmittance t of p-waves is p and the amplitude reflectance r p , and the amplitude transmittance of s-waves t s and the amplitude reflectance r s are respectively: t p =2sinθ T cosθ I / {sin(θ I +θ T )cos(θ I -θ T )} (6) r p = tan(θ I -θ T ) / tan(θ I +θ T ) ···(7) t s =2sinθ T cosθ I / sin(θ I +θ T ) ···(8) r s =-sin(θ I -θ T ) / sin(θ I +θ T ) ···(9) and the transmittance of p-waves is T p and reflectance R p , s-wave transmittance T S and reflectance R S are respectively: T p =tp 2 tan θ I / tanθ T (10) R p =r p 2 (11) T S =t s 2 tan θ I / tanθ T (12) R S =r s 2 (13) In the above-mentioned Pyrex glass (refractive index n=1.47), the refraction angle θ calculated from the formulas (4) and (6) to (13) shown in FIG. T and the p-wave transmittance T p , and the refraction angle θ T and the s-wave transmittance T S From the relationship, θ T In the vicinity of =90°, the refraction angle θ T With the increase in transmittance (T p and T S ) both decrease rapidly and approach 0. The refraction angle θ in Pyrex glass T = 87.14°, the incidence angle θ I = 42.80°, and from equations (4) and (6) to (13), T p =0.328, R p =0.673, T S = 0.168 and R S = 0.832, and only 32.8% of the p-waves and 16.8% of the s-waves of the incident light 22 are refracted.

[0037] In this specific example, Pyrex glass (refractive index n=1.47) is used as the first medium, and the light is incident on the road surface 21 at a predetermined angle of incidence θ I is determined according to the relative refractive index of the first medium with respect to the second medium (air in the above example).

[0038] <Parallelogram Shape of Light Guide 12> FIG. 4 is a vertical cross-sectional view of the light-emitting device 10 in this embodiment, and shows the light-emitting device 10 shown in FIG. 1 in combination with the relationship of the light paths of light described with reference to FIG. 2. In FIG. 4, hatching showing a cross section is omitted for convenience so that the light paths and the like can be clearly shown. The same applies to the following figures. As shown in FIG. 4, the light guide 12 in this embodiment has a parallelogram shape in the vertical cross section, and a reflector 18 is provided on the left slope 12b, the lower surface 12c, the right slope 12d, and the side surfaces other than the upper surface 12a that forms the road surface 21. As described above, the reflector 18 provided on the side surface is omitted from the figure. In this embodiment, for convenience of explanation, the same symbol is given to "light" and "light path".

[0039] The characteristic feature of this embodiment is that, when light is emitted using refraction, the reflected light at the boundary surface 21 is effectively utilized. In particular, in order to be able to deal with the case where the predetermined target position to which the light is to be delivered is at a low position, the light reflected at the boundary surface 21 is repeatedly made incident on the boundary surface at the same incident angle as a method of emitting strong light at a small elevation angle from the road surface 21, in other words, a method of emitting strong light at a large refraction angle. If the incident angle of the light incident on the boundary surface is made larger in order to emit light at a larger refraction angle, the ratio of the refracted light to the incident light becomes smaller, and the light intensity of one emission becomes relatively weak. Therefore, in this embodiment, the structure of the light emitting device 10 is designed so that the reflected light at the boundary surface can be repeatedly made incident on the boundary surface at the same predetermined incident angle, so that the light emitting device 10 can emit strong light, i.e., high brightness.

[0040] The light guide 12 in this embodiment is a quadrangular prism with a parallelogram bottom surface (front surface shown in FIG. 1(b)), and is embedded in the road so that the bottom surface is perpendicular to the road surface 21 and one of the side surfaces (top surface 12a shown in FIG. 4) is in contact with the road surface 21. As shown in FIG. 4, refracted light 23 is emitted to the acute angle side of the road surface 21 (left side in FIG. 4). By forming the light guide 12 in a parallelogram prism shape, the incident angle θ of light with respect to the boundary surface 21 is I This allows you to efficiently achieve the same angle every time.

[0041] The optical path within the light guide 12 is as follows. First, as shown in Fig. 4, light from the light source 14 is incident on the incident portion 16. To suppress reflection at the incident portion 16 and to increase the transmitted light to the light guide 12, it is desirable for the light to be incident from vertically below the lower surface of the light guide 12. The light incident on the light guide 12 is reflected by the right inclined surface 12d and then incident on the upper surface 12a. A portion of the light 23 of the incident light 22 on the upper surface 12a is refracted at a large refraction angle θ T The remaining light 24 is reflected and travels inside the light guide 12. The reflected light 24 from the upper surface 12a is reflected in this order by the left slope 12b, the right slope 12d, and the lower surface 12c, and becomes incident light 22a at the same incident angle θ as the first incident light. I Then, a part of the incident light 22a is refracted at the same large refraction angle θ T The remaining part is reflected and travels through the light guide 12. The second incident angle θ I is the same as the first time, so the refracted light 23a with respect to the second incident light 22a has the same refraction angle θ as the first refracted light 23. T is emitted at

[0042] In this way, the refracted light 23 emitted from the upper surface 12a of the light source 14 is refracted at the same refraction angle θ T On the other hand, the light 24 reflected by the upper surface 12a from the light source 14 is reflected by the reflector 18 repeatedly inside the light guide 12 along the same optical path, and is emitted at the same predetermined incident angle θ I The light 22 is then incident on the upper surface 12a at the same refraction angle θ T The refracted light 23 is repeatedly emitted.

[0043] In this embodiment, the vertical cross section of the light guide 12 is a parallelogram. I is always the same, there is no need to limit it to parallelograms.

[0044] Next, in the case where the shape of the vertical cross section is a parallelogram like the light guide 12 in this embodiment, the incident angle θ of light to the upper surface 12a I The reason why is equal every time is as follows.

[0045] 5 shows the same light guide 12 as in FIG. 4. In the parallelogram ABCD of the vertical cross section of the light guide 12, the point where the light beam enters the side AB (upper surface 12a in FIG. 4) for the m-th time, and the points where the light beam enters the side BC (left slope 12b in FIG. 4), the side DA (right slope 12d in FIG. 4), and the side CD (lower surface 12c in FIG. 4) thereafter are respectively denoted by a m , b m , d m , c m The incidence angle at each point is α m , β m , δ m , γ m Point a m The light reflected by then passes through b m , d m , c m , a m+1 The angle of incidence is the angle with respect to the perpendicular line of the boundary surface, but since the angle of incidence and the angle of reflection are equal, the angle of incidence α m ~δ m and α m+1 As shown in Figure 5, if the angle of vertex B is written as "△Β (beta)" and simply "Β" in the formula, the angle of vertex D, which is the diagonal angle of vertex B of parallelogram ABCD, is also △Β. △a m Bb m and △c m Dd m Since the sum of the interior angles is 180°, (90°-α m )+Β+(90°-β m )=180° (14) (90°-γ m )+Β+(90°-δ m )=180° (15) Also, sides AB and DC, and sides AD and BC are parallel and their alternate angles are equal, so (90°-γ m )=(90°-α m+1) ···(16) (90°-δ m )=(90°-β m ) ···(17) Substituting equations (16) and (17) into equation (15), we get (90°-α m+1 )+Β+(90°-β m )=180° (18) From equations (14) and (18), α m+1 = α m In other words, the (m+1)th incident angle to the upper surface is equal to the mth incident angle, so it can be said that the incident angle to the upper surface is the same every time. In the following explanation, the incident angle to the upper surface is represented as "α". Also, from equation (16), the incident angle to the lower surface γ m also becomes α.

[0046] In Figure 5, point a on the top surface m After the light is incident and reflected at point b on the left slope m However, if the base is made long enough relative to the height of the parallelogram of the cross section, the light will enter at point a. m After being incident and reflected at point c on the bottom surface m The light is incident on the top surface and reflected at point a m+1 The light is incident on the upper and lower surfaces and reflected from them repeatedly. The light path in this case is shown in Figure 6.

[0047] In this case, sides AB and DC are parallel and their alternate angles are equal, so together with equation (16), (90°-γ m )=(90°-α m ) ···(19) holds, and from equations (16) and (19), α m+1 = α m Thus, the angle of incidence on the upper surface is equal every time, and the angle of incidence on the lower surface is equal to that on the upper surface.

[0048] Incidentally, the angle B of the acute vertex B in the vertical cross section of the parallelogram of the light guide 12 can be set in various ways using the incident angle α.

[0049] First, one method for setting the angle ΔB will be described with reference to FIG.

[0050] For example, light from the light source 14 is incident on the light guide 12 at a point c 0 Consider the case where the light is incident vertically on the lower surface. In this case, the incident light is incident on point d on the right slope. 0 At the incidence angle δ 0 and the incidence angle is δ 0 Then, it is reflected at the same angle as the 1 The advantage of making the light perpendicular to the incident portion 16 of the light guide 12 is that the incident light is not refracted but is reflected by the incident light at an angle of θ T = 0°, and as shown in FIG. 3, the proportion of light that passes through the surface and enters the light guide 12 is high. 0 The angles of incidence and reflection at are equal, ∠c 0 d 0 D=∠a 1 d 0 A(=90°-δ 0 ) ···(20) So, △c 0 d 0 D and △a 1 d 0 The sums of the other two angles of A are equal. ∠d 0 c 0 D+∠c 0 Dd 0 =∠d 0 a 1 A+∠a 1 Ad 0 ···(twenty one) In addition, the angle of vertex B of parallelogram ABCD is △Β, and the angle of vertex A is 180°-Β, so equation (21) is 90°+Β=(90°-α)+(180°-Β) ···(22) And then, Β=90°-α / 2 (23) For example, α is expressed as θ in Eq. (4). I = 42.80°, then angle B becomes 68.60° according to equation (23).

[0051] Next, another method for setting the angle ΔΒ of vertex B will be described with reference to FIG. 8.

[0052] The angle ΔΒ can also be set under the condition that the light reflected by the left inclined surface 12b of the light guide 12 (b in FIG. 8) 1 d 1 ) is parallel to the road surface 21. This condition has the advantage of being able to reduce the height (the vertical length in FIG. 8) of the parallelogram in the vertical cross-section. When b 1 d 1 is parallel to the road surface 21, side AB and side b 1 d 1 are parallel, and from the corresponding angles, ∠a 1 Bb 1 =∠d 1 b 1 C (= angle ΔΒ) ···(24) and since the incident angle and the reflection angle with respect to b 1 are equal, ∠a 1 b 1 B = ∠d 1 b 1 C (= angle ΔΒ) ···(25) Thus, △a 1 b 1 B is an isosceles triangle with a 1 B = a 1 b 1 and the sum of the interior angles 2Β+(90° - α)=180° ···(26) From Β = 45°+α / 2 ···(27) is obtained. For example, when α is θ in Equation (4) I= 42.80°, ΔΒ is 66.40° according to formula (27). Formula (27) is different from formula (23), so in most cases, the angle of incidence from the light source 14 to the light guide 12 is not 0°. In other words, it is not perpendicular to the incident part 16. However, when the angle of incidence is small, for example, as shown in FIG. 3, the proportion of transmitted light is very high, and the intensity of the light that is refracted and enters the light guide 12 is high. Therefore, in order to increase the intensity of the light that enters the light guide 12, it is preferable to arrange the light source 14 so as to suppress the reflected light of the light that is irradiated toward the incident part 16. In this way, when it is necessary to further increase the intensity of the light that enters the light guide 12, methods of doing so include directly attaching the light source 14 to the incident part 16 of the light guide 12, filling the area from the light source 14 to the light guide 12 with a medium that has the same refractive index as the light guide 12, and cutting the vicinity of the incident part 16 (for example, apex D) so as to be perpendicular to the incident direction.

[0053] As shown in FIG. 6, when the light from the light source 14 is repeatedly reflected on the upper surface (road surface) and the lower surface, the number of repetitions can be increased, so it is better for the ratio of the base to the height in the parallelogram ABCD of the cross section to be large. On the other hand, even if the light is reflected on the upper surface as described above, and then reflected on the side BC (left slope), side AD (right slope), and side CD (lower surface) in that order, and then enters the upper surface again, the ratio of the base to the height can be set so that the number of refractions and reflections on the upper surface increases. Prior to setting the ratio, the condition for ending the incidence on the upper surface at the same incidence angle α will be explained using FIG. 9. The reason for showing this condition first is that the ratio of the base to the height can be determined from the viewpoint of delaying the satisfaction of the condition for ending the incidence.

[0054] Here, the same as the condition in FIG. 8, b of the left slope 12b 1 Light reflected by b 1 d 1 In this case, the condition for the incidence on the upper surface at the incidence angle α to end is as follows. However, as shown in FIG. 9, the incidence point a on each of the surfaces 12a to 12d m ~d m When reflection is repeated, that is, when m becomes large, a m and c mto the left of the corresponding sides AB and CD, m and d m The points c are the intersection points of the line drawn from vertex B to side AB at an angle of 90°-α with side CD. NG Let us assume that m C NG If you go to the left of c m The light reflected by the left slope 12b (shown in FIG. 9) is reflected by the left slope 12b before reaching the top surface 12a. NG ), and is reflected, and then incident on the upper surface 12a at an angle of incidence smaller than α (a shown in FIG. 8). NG ) and the incidence at the incidence angle α ends. Therefore, as shown in FIG. 9, the condition for the incidence of the light on the upper surface 12a at the incidence angle α is that the light is incident at the incidence position c m C NG It can be said that it is to the left of

[0055] As described above, when light is repeatedly reflected inside the light guide 12, c m Move to the left and click NG To approach c, in order to increase the number of incidences on the top surface, m It is necessary to determine the shape of the vertical cross section of the light guide 12 so that the light guide 12 is as far to the right as possible. m If is further to the right, a m To the right of the m and d m When light from the light source is incident on the lower side of the light guide 12, as described above, d 0 After reflection at a 1 (e.g., Fig. 7 and Fig. 8), and then b 1 , d 1 , c 1 , a 2 In this case, b 1 Or d 1 The lower the position of, the more times the light is incident on the top surface at an angle of incidence α, but 1 Or d 1 When the positions of are close to the bottom ends of the left slope 12b and the right slope 12d, respectively, 1 The light reflected by the reflector 16 enters the incident portion 16 (c 1exists within the incident portion 16), and part of the light will exit from the incident portion 16 as refracted light to the lower side of the light guide 12.

[0056] Based on the above description, for the parallelogram ABCD which is the vertical cross-section of the light guide 12, the ratio of the base to the height such that the number of times of incidence on the upper surface increases is designed as follows.

[0057] As described with reference to FIGS. 8 and 9, the light incident from the light source 14 into the light guide 12 is 0 , a 1 , b 1 , d 1 , c 1 , a 2 reflected in this order. FIG. 10 is a view showing the vertical cross-section of the light guide 12, similar to FIG. 8. Here, consider the case where b 1 d 1 is incident on the light guide 12 parallel to the upper and lower surfaces, and at a position near the lower end, d 0 = d 1 is satisfied, and c 1 is on the reflector 18, that is, not at the position of the incident portion 16. Let the perpendiculars from a 1 to the side CD and the intersections with b 1 d 1 and the side CD be e and f, respectively. For △a 1 b 1 e and △a 1 d 1 e, the side a 1 e is common, and ∠b 1 a 1 e = ∠d 1 a 1 e (= α, the angle of incidence and the angle of reflection) ···(28) ∠a 1 eb 1 = ∠a 1 ed 1 (= 90°) ···(29) Therefore, they are congruent right triangles, and eb 1 = ed 1 = a 1 b 1 sinα, a 1 e = a 1 b 1cosα. Therefore, the base of the parallelogram ABCD is b 1 d 1 Equal to 2eb 1 =2a 1 b 1 sinα, height is a 1 e+ef=a 1 b 1 cosα+ef, base:height=2sinα:cosα+Δ(Δ=ef / a 1 b 1 ) In equation (4), θ I = α, the ratio of the base to the height of the parallelogram in the cross section of the light guide 12 can be roughly determined by determining the incident angle α from the refractive index n of the material of the light guide 12. In other words, the ratio of the base to the height of the parallelogram ABCD can be set according to the relative refractive index of the light guide 12 (first medium) to that of air (second medium).

[0058] For example, in the case of the aforementioned Pyrex glass, θ I = 42.80°, so base:height = 1.36:0.734 + Δ. The approximate value of Δ is determined from the size of the incident portion 16. Similarly, in the case of repeated reflection on the upper and lower surfaces shown in Fig. 6, in order to increase the number of reflections on the upper surface, the shape of the cross section can be designed so that the position at which the light enters the left slope after reflecting near the left end of the upper surface is closer to the lower end.

[0059] In this embodiment, the incident portion 16 is provided on the bottom surface (side CD) of the light guide 12, but from the above, it is preferable to consider the position and size of the incident portion 16 in consideration of the position of the light source 14, etc., as well as the fact that the number of reflections inside the light guide 12 is increased. As a result, the incident portion 16 is not limited to being provided on the bottom surface (side CD) of the light guide 12, and may be provided on, for example, the right side surface (side AD) or the left side surface (side BC).

[0060] <Optical Simulation> The behavior of light when the light guide 12 having the proposed shape is used was verified by optical simulation. The software used for the simulation was COMSOL Multiphysics (registered trademark), and the simulation was performed for the following three light sources a to c. Light source a: A monochromatic light source that does not spread, such as a laser beam Light source b: A monochromatic light source with an illumination angle, i.e., a spreading light source Light source C: A non-diverging white light source

[0061] First, an optical simulation using the light source a was carried out to verify that the light guide 12 having the proposed shape repeatedly incidents light on the upper surface (road surface) at the same incident angle and emits refracted light. The calculation conditions are as follows. Condition 1: Material of the light guide 12: BK7 (refractive index 1.523 @ wavelength 480 nm) Condition 2: Bottom size of the light guide 12; bottom side 100 mm, height 64 mm, acute angle = 65.51° Condition 3: Light source; wavelength 480nm Condition 4: Angle of incidence of light from the light source to the incident portion 16: 12.16°

[0062] The acute angle, that is, the angle ΔB of the vertex B described above, satisfies the formula (27), which is the condition for the reflected light from the left slope 12b to be parallel to the road surface 21, as shown in FIG.

[0063] The simulation results based on the above conditions 1 to 4 are shown in FIG.

[0064] The light emitted from the light source 14 enters the light guide 12 from the entrance 16 at a refraction angle of 7.95°, is reflected by the right slope 12d, and then enters the top surface 12a at an incident angle of 41.02°. A part of the light exits the light guide 12 at a refraction angle of 88.28°, and the rest is reflected. In this case, the refracted light intensities of the p-wave and s-wave are 21.5% and 9.9% of the incident light, respectively. In the present conditions 1 to 4, the reflected light is repeatedly incident on the top surface 12a at the same incident angle a total of seven times, and is reflected by the left slope 12b before being incident on the top surface 12a for the eighth time. The circled numbers in FIG. 11 indicate the light that is directed toward the top surface 12a for the mth time (m=1 to 8).

[0065] The cumulative intensity of the refracted light of p-waves and s-waves from the upper surface 12a for seven incidences was 81.7 and 51.9% of the incident light, respectively, and it was derived by optical simulation that light with intensities 3.8 and 5.2 times greater, respectively, can be emitted from the road surface 21 compared to the refracted light from only the first time (first incident light). Since the refraction angle is 88.28°, if the refracted light from the road surface 21 is used to notify approaching vehicles, and the driver's eye height is 1.5 m above the ground, then the light emitting device 10 using the light source a will emit light toward a vehicle 50 m ahead of the marking position from which the refracted light is emitted, according to formula (1).

[0066] In other words, according to this embodiment, it is possible to emit stronger light with a large refraction angle from the road surface (88.28° in the above simulation), in other words, a small elevation angle from the road surface, which in the above simulation is 1.72°, which is close to 0°, and with a single irradiation.

[0067] According to an optical simulation using light source a, the light emitting device 10 emits light only toward vehicles traveling 50 m before the target position of the light, i.e., the road marking position. However, it is desirable to be able to continuously notify the vehicle while it is approaching the road marking position. In other words, in order to expand the target position to which the light is to be emitted, in other words, the range (i.e., distance) in which the driver can detect the light emitted from the light emitting device 10, it is sufficient to use a light source that spreads, i.e., a light source with an illumination angle. Therefore, an optical simulation using the above light source b was carried out to verify this.

[0068] For the calculation conditions given to light source a, light source b having an illumination angle of half-value angle 2° was used instead, and the incident angle of light from light source 14 to incident portion 16 was changed to (11.34±1)°, and an optical simulation of light source b was performed. The simulation results are shown in FIG.

[0069] The range of incident angles in the calculation of light source b includes the values ​​in the calculation conditions of light source a. That is, the light reflected by boundary surface 12a and the left slope 12b becomes parallel to road surface 21. The refracted light from road surface 21 is emitted at a refraction angle in the range of 85.71 to 90°. When the refracted light is used to notify a driver whose eyes are 1.5 m above the ground, the notified point is within a range of 20 m or more from the road marking position according to formula (1). That is, when light source b is used, light emitting device 10 can irradiate light toward a vehicle traveling at a position 20 m or more away from the road marking position.

[0070] Since the shorter the wavelength of light is, the greater the refractive index, if white light is used, it is possible to irradiate the road surface 21 so that the color of the light changes from blue to yellow to red as the road surface marking location is approached. In order to verify this point, calculations were performed using light source c. The calculations were performed for light source 14, which emits light with wavelengths of 380 to 770 nm at intervals of approximately 5 nm, and the other calculation conditions were the same as those for light source a. The results of this simulation are shown in Figure 13.

[0071] In FIG. 13, (a) shows the spectrum of light received at 1.5 m above ground at a distance of 50 m, (b) shows the spectrum of light received at 16 m, and (c) shows the spectrum of light received at 13 m from the road marking point on the light guide 12, and the refracted light has refraction angles of 88.28°, 84.64°, and 83.41°, respectively. In the graph shown in FIG. 13, the horizontal axis is the wavelength of light (nm), and the vertical axis is the power (W). The refracted light at the points 50 m, 16 m, and 13 m away from the road marking point has wavelengths of blue (480 nm), yellow (568 nm), and red (646 nm), respectively. In other words, the light appears blue at a relatively low elevation angle, red at a relatively high elevation angle, and yellow at elevation angles between them. In other words, the optical simulation here utilizes the fact that the refractive index changes depending on the wavelength of light. Specifically, optical simulations verified that when white light is used, the color of the light emitted from the road surface changes from blue to yellow to red as the vehicle approaches the road marking point.

[0072] As shown in Fig. 13(c), at a point 13 m away from the road surface marking point, the power is calculated to be less than 0.002 W even at the peak wavelength ± 5 nm. However, since the wavelengths are close, it can be said to be red together with the peak wavelength.

[0073] <Relationship between light intensity and irradiation position> When the above-described light-emitting device 10 is used as a road surface marking device, in order to consider the arrangement of the road surface marking device, the relationship between the light intensity received by the driver's eyes and the irradiation position of the light is shown below. The irradiation position of the light is the same as the point where the road surface marking device is installed. The light distribution characteristic of the light source is assumed to be a normal distribution with respect to the angle θ with the optical axis. In this case, the irradiation angle (the angle between the direction in which the light intensity becomes half on the optical axis and the optical axis) θ h is used, and the light intensity distribution I(θ) is I(θ)=(1 / πθ h 2 ) / ln2)×exp{-θ 2 / (θ h 2 / ln2)} ···(30) is expressed as. The irradiation angle θ h refers to the angle between the direction in which the light intensity becomes half on the optical axis and the optical axis. The refraction due to the incidence of light from the incident portion 16 to the light guide 12 is ignored, and the case where light satisfying the formula (30) is incident on the upper surface of the light guide 12 is considered. When the optical axis (that is, θ = 0°) is incident on the upper surface at the incident angle θ C , with the intensity distribution of the formula (30), it is incident at the incident angle θ I =θ C +θ and exits in the direction of the refraction angle of θ T satisfying the formula (3).

[0074] On the other hand, in the driver's eyes that receive light, when the height of the pupil from the ground is H, the width is ΔH, and the range of the pupil height is from H - ΔH / 2 to H + ΔH / 2, the driver will see the refracted light within this range. The standard value of ΔH is 2 mm during the day and 8 mm at night. When the distance from the driver to the light source is L, the range of the elevation angle θ E of the light from the road surface marking (corresponding to the above-described light guide 12) recognized by the driver is (H - ΔH / 2) / L ≦ tanθE ≦(H+ΔH / 2) / L (31) twist, arctan{(H-ΔH / 2) / L}≦θ E ≦arctan{(H+ΔH / 2) / L} (32) and the refraction angle θ T The range is 90°-arctan{(H+ΔH / 2) / L}≦θ T ≦90°-arctan{(H-ΔH / 2) / L} ···(33) In this case, θ T The lower limit, center and upper limit of θ T.B , θ T.C and θ T.U Then, they are 90°-arctan{(H+ΔH / 2) / L}, 90°-arctan(H / L), and 90°-arctan{(H-ΔH / 2) / L}, respectively. The incidence angle θ that satisfies these is I is calculated by equation (3), and the lower limit, center and upper limit are θ I.B , θ I.C and θ I.U The reflected light intensity after the repeated incidence of the light on the upper surface of the light guide 12 can be ignored compared to the first incident light, and θ I.B From θ I.U Assume that the change in I(θ) between the light guide 12 and the driver's eye can be ignored. The horizontal light spread is not affected by refraction and is proportional to the distance √(L 2 +H 2 ) is proportional to the following parentheses (here, (L 2 +H 2 In this case, the light intensity received by the driver is the light intensity ratio I t (I for one light source t =1), θ I.C The light intensity distribution I(θ I.C -θ C ), θ I Width θ I.U -θ I.B and the reciprocal of the distance from the road marking, 1 / √(L 2 +H 2) and the product of these is E D Let E be the light emitted by one light source. D teeth, E D (L)=I t I(θ I.C -θ C )·(θ I.U -θ I.B ) / √(L 2 +H 2 ) ···(34) The light spreads in two directions, that is, perpendicular and parallel to the road surface 21, but the light intensity E D In the formula (34) which shows I.U -θ I.B ) and 1 / √(L 2 +H 2 ) reflects these.

[0075] FIG. 14 shows the E calculated according to the first calculation condition. D The horizontal axis is the distance L from the light guide to the driver, and the vertical axis is the light intensity E (reflecting the light intensity) received by the driver's eyes from the road marking. D The same applies to Figs. 15 and 16 used in the following description. The first calculation condition for obtaining the calculation result shown in Fig. 14 is the light intensity I t = 1, the incidence angle θ of the light source 14 C = 42.8°, refraction angle θ h = 0.05°, the height of the driver's pupil from the ground H = 1.5 m, and ΔH = 2 mm (daytime conditions). Under these calculation conditions, θ h Even if the value is as small as =0.05°, the driver receives light over a wide range of L≧18m. D is maximum at around L = 25m, and when L is doubled to 50m, E D is approximately 1 / 10 of the maximum value. The light intensity of the spreading light is inversely proportional to the square of the distance, but in this calculation, the attenuation rate of the light intensity when L is 25m to 50m is greater than 4 times, which is the square of the distance ratio (2 times). The large attenuation rate is due to the light spreading in the vertical direction of the road surface due to refraction, and the θ T.U -θ T.BThe angle of incidence of the incident light θ decreases by half from 0.0046° at 25 m to 0.0023° at 50 m. I.U -θ I.B The angle is reduced by about 1 / 5 from 0.00033° when L is 25 m to 0.000064° when L is 50 m. In the above calculation, the intensity of the incident light is maximized at θ=0°, i.e., θ I =θ C = 42.8°, as is clear from equations (1) to (4), the refracted light reaches a point at L = 30 m, while E D The maximum value of is around L = 25 m. In the L = 25 to 30 m section, the increase in L has a larger effect of spreading the light than the increase in the incident light intensity, so E D decreases.

[0076] In the first calculation condition for obtaining the calculation results shown in Figure 14, when L is smaller than 25 m, E D decreases rapidly, and E D is almost 0, and no light is emitted from the road marking. The illumination angle θ is larger than that of the first calculation condition. h When using a light source 14 with a smaller L range, the driver receives light. D A calculation example is shown in Figure 15.

[0077] The second calculation condition for obtaining the calculation result shown in FIG. 15 is to change the condition of the light source 14 from the first calculation condition by changing the incidence angle θ C =42.35°, illumination angle θ h =0.5°, θ C +θ h θ h is set to 10 times, 0.5°. The height conditions (H = 1.5 m, ΔH = 2 mm) are the same as those for the first light source. Under the second calculation conditions, the light intensity E D Not only are there still short L (≦5m) where E is nearly 0, but also E at L=50m D is 0.0019, which is extremely small, 1 / 280 of the peak value of 0.53 (L=9 m). Therefore, it is not realistic to use one light source 14 to irradiate a wide range of L, for example, the entire range of L≦50 m.

[0078] The light intensity E of the road marking using a plurality of light sources 14 as the light source means D An example of the calculation result is shown in FIG. 16. In order to obtain the calculation result shown in FIG. 16, the irradiation angle θ h Using three light sources 14 with different light intensities, the light intensity E D The light intensity I of the light source 14 is set so that T and the incidence angle θ C This is an example of the result of adjusting the first light source (illumination angle θ h = 7°), the light intensity E from the second light source (= 0.5°) and the third light source (= 0.05°) D The peaks are at L = 2, 8 and 25 m, respectively.

[0079] The first light source has a light intensity I t =24, angle of incidence θ C = 36°, and the second light source has a light intensity I t =3.4, angle of incidence θ C = 42.25°, and the third light source has a light intensity I t =1, angle of incidence θ C = 42.8°. The height conditions (H = 1.5 m, ΔH = 2 mm) are the same for the first to third light sources. The light intensity E D The minima of are at L=5 and 17 m, where the primary light source for the pavement marking switches from the first light source to the second light source and from the second light source to the third light source, respectively.

[0080] In this way, by combining a plurality of light sources to form a light source means, the driver can see the road markings from positions far from the road markings, close to the road markings, and from positions in between.

[0081] In addition, the light intensity E D is a value when the driver's eyes are on a plane that includes the optical axis of the light source 14 and is perpendicular to the road surface. When the driver's eyes are not on this plane, for example, when the driver's eyes are shifted from the plane shown in FIG. 2 in a direction perpendicular to the road surface 21, the light intensity ED The value of becomes even smaller. In particular, the illumination angle θ h In the case of a third light source with a small value, at L=30m where the eye height coincides with the optical axis, the distance from the point where the light intensity is half that of the optical axis to the optical axis is: √(L 2 +H 2 )·tanθ h (35) =√(30 2 +1.5 2 )·tan 0.05° =0.026[m] If the light axis is shifted by just 2.6 cm, the light intensity E D In order to emit strong light on areas other than the vertical plane of the road surface including the optical axis, the illumination angle θ h Methods include using a light source where the value of the vertical direction is greater than the value in the vertical direction, and placing road markings at close intervals in the normal direction of the vertical plane.

[0082] <Structure of road marking device> The road marking device of this embodiment can be used as it is, for example, with the light emitting device 10 shown in FIG. 1 as its basic structure.

[0083] 17 is a diagram showing an example of the structure of a road marking device in this embodiment. The road marking devices 30 are disposed on both sides of the crosswalk 20. Note that when subscripts are attached to the road marking devices 30a, 30b and there is no need to distinguish between them, they will be collectively referred to as "road marking device 30." The same applies to the following explanation.

[0084] 1 are arranged along the crosswalk 20 and installed on the road surface 21. The road surface marking device 30a installed to the left of the crosswalk 20 in the drawing emits light in the direction of arrow A, which indicates an approaching vehicle. Meanwhile, the road surface marking device 30b installed to the right of the crosswalk 20 in the drawing emits light in the direction of arrow B, which indicates an approaching vehicle. In this embodiment, the road surface marking devices 30 are installed on the road surface 21 so as to sandwich the crosswalk 20, but if the only purpose is to inform drivers that the crosswalk 20 is ahead, it is sufficient to install the road surface marking devices 30 only at positions corresponding to the approaching direction of vehicles.

[0085] The light from the light sources 14 corresponding to each light-emitting device 10 that is refracted at the upper surface of the light guide 12 is irradiated toward the vehicle, which is expected to have the effect of alerting the driver to the presence of pedestrians crossing the crosswalk 20 and the crosswalk 20 itself.

[0086] Fig. 18 is a diagram showing another example of the structure of the road marking device in this embodiment. As illustrated in Fig. 17, when one light guide 12 is provided for each light source 14, the light emitting device 10 including one light source 14 and one light guide 12 as a pair is embedded on both sides of the crosswalk 20. In contrast, the road marking device 32 shown in Fig. 18 is embedded on both sides of the crosswalk 20 like the road marking device 30 shown in Fig. 17, but all of the multiple light sources 14 with the same irradiation direction are provided on one light guide 121. In this case, only one light emitting device including a light guide 121 needs to be installed on one side of the crosswalk 20.

[0087] Fig. 19 is a diagram showing another example of the structure of a road marking device in this embodiment. In a road marking device 32 shown in Fig. 18, all of the light sources 14 provided on one entire side of a crosswalk 20 are associated with one light guide 121. In a road marking device 34 shown in Fig. 19, instead of all of the light sources 14, a plurality of light sources 14 (three in Fig. 19) are associated with one light guide 122, and a plurality of light-emitting devices equipped with the light guide 122 are installed side by side on one side of the crosswalk 20. The light-emitting devices shown in Fig. 19 require fewer installations than those shown in Fig. 18, and are easier to carry than those shown in Fig. 19.

[0088] 17 to 19, one light source 14 is shown by a dotted line as light source means. As mentioned above, a plurality of light sources 14 may be used as light source means, and in this case, the plurality of light sources are collectively shown as one light source 14 in Fig. 17 to 19. The plurality of light sources included in the light source 14 are arranged along the crosswalk 20.

[0089] In the present embodiment, the description has been given with a focus on irradiation in the longitudinal direction of light guide 12 (the direction in which a vehicle is approaching) as shown in Fig. 11 and Fig. 12. However, light guide 12 has a thickness. Also, although it may depend on the positional relationship between light source 14 and incident portion 16 and the shape of incident portion 16, there is a possibility that light from light source 14 is reflected by reflectors 18 on the top and bottom surfaces of the parallelogram in the vertical cross section of light guide 12, and is irradiated in a direction other than the direction in which a vehicle is approaching. In other words, there is a possibility that it is possible to notify pedestrians and the like near crosswalk 20 of the presence of crosswalk 20.

[0090] In order to allow pedestrians near the crosswalk 20 to recognize the road marking device, it may be necessary to expand the light emission in directions (collectively referred to as "horizontal directions") other than the direction in which the vehicle approaches (herein referred to as "vertical direction"). Even if the vertical illumination angle is ±0.05°, it would be problematic if the light cannot be seen in the horizontal direction, so in order to expand the visible range, the horizontal illumination angle may be expanded to, for example, ±10.00°. In this way, the vertical and horizontal illumination angles may be set to different values. If the horizontal illumination angle is narrowed to ±0.05°, the same as the vertical direction, this may be addressed by narrowing the installation interval of the light sources 14.

[0091] <Road surface lighting unit> In order to mount the road marking device on a road, in this embodiment, a road light emitting unit that houses the road marking device is produced. The road marking device may be formed by a plurality of light emitting devices as shown in Fig. 18 and Fig. 19, but the road light emitting unit may be formed for each light guide, that is, for each light emitting device. Alternatively, it may be formed so as to be able to house a plurality of light emitting devices together.

[0092] Although the road marking device 30 is formed by one light-emitting device 10 or by combining a plurality of light-emitting devices 10, the road marking device 30 will be described here by taking as an example the light-emitting device 10 shown in Fig. 1 or 17, that is, a road light-emitting unit for accommodating the light-emitting device 10 in which one light guide 12 is associated with one light source 14. Therefore, for convenience of explanation, the road marking device and the light-emitting device are used synonymously.

[0093] FIG. 20 is a diagram showing an example of a road surface light emitting unit in this embodiment, where (a) is a top view, (b) is a front view, and (c) is a bottom view. The upper part of the road surface light emitting unit 40 shown in FIG. 20 has a space 42 for storing the light guide 12, and the light guide 12 can be fixed to the road surface light emitting unit 40 by making the shape of the space 42 the same as that of the light guide 12. The lower part of the road surface light emitting unit 40 has a space 44 for installing the light source 14, and is provided with a jig (not shown) such as a socket for fixing the light source 14. This jig may be detachable from the road surface light emitting unit 40, and the jig to which the light source 14 is fixed may be attached to the road surface light emitting unit 40. Alternatively, the light source 14 may be attached to the jig fixed to the road surface light emitting unit 40. In order for the light from the light source 14 to pass through the incident part 16 of the light guide 12, the space 44 in which the light source 14 is installed is connected to the space 42 that houses the light guide 12 at a position where the incident part 16 of the light guide 12 fits, and it is designed so that when the light guide 12 and the light source 14 are attached to the road surface light-emitting unit 40, the light from the light source 14 enters the incident part 16 at a predetermined angle (see Figures 7 and 8). A plug 46 for supplying electricity from outside the road surface light-emitting unit 40 is provided at the bottom of the socket, and electricity is supplied to the light source 14 by inserting the plug 46 into an external plug receptacle, whereby the light source 14 becomes ready to be turned on.

[0094] 20 is a housing means corresponding to the light emitting device 10 having one light source 14 for the light guide 12 shown in FIG. 17 as described above. The light guide 121 shown in FIG. 18 and the light guide 122 shown in FIG. 19 are both parallelogram-shaped rectangular prisms similar to the light guide 12. The spaces 42, 44 in the road surface light emitting unit for housing the light emitting device having one light guide 121, 122 may be basically prepared to correspond to the shape of the light guides 121, 122 and the position of the light source 14, similar to the road surface light emitting unit 40.

[0095] Fig. 21 shows another example of the road surface light emitting unit in this embodiment, where (a) is a top view, (b) is a front view, and (c) is a bottom view. The road surface light emitting unit 40 shown in Fig. 20 is a parallelogram-shaped quadrangular prism similar to the shape of the light guide 12, but may be a rectangular parallelepiped like the road surface light emitting unit 50 shown in Fig. 21. The road surface light emitting unit 50 differs from the road surface light emitting unit 40 shown in Fig. 20 only in shape, and is provided with a space 52 for accommodating the light guide 12, a space 54 for installing the light source 14, and a plug 56 for supplying electricity from outside the road surface light emitting unit 50, just like the road surface light emitting unit 40.

[0096] The above-mentioned road surface lighting units 40, 50 may be configured so that the light guide 12 and the light source 14 are fixed separately rather than being integral with each other, as long as the light can be incident from the light source 14 to the incident portion 16 of the light guide 12 at a predetermined angle.

[0097] <Method of installing road marking devices on roads> Here, a method for embedding a road marking device in a road using the road light emitting unit 50 shown in FIG. 21 will be described with reference to FIG.

[0098] 22, (a) and (b) show the state of the road after the mold described later is pulled out, and (c) and (d) show the state of the road after the road surface light emitting unit 50 containing the road surface marking device is buried. Also, (a) and (c) are plan views of the position where the road surface light emitting unit 50 is buried, as seen from above the road, and (b) and (d) are side cross-sectional views taken along the line AA' shown in (a) and (c).

[0099] First, when paving a road, an electric wire (not shown) with a plug receptacle 62 is buried in advance below the buried position of the road surface light emitting unit 50. Then, a mold (not shown) that is slightly larger than the road surface light emitting unit 50 is placed at the position of the plug receptacle 62, and after the road is paved, the mold is pulled out from the road. When burying a rectangular parallelepiped-shaped road surface light emitting unit 50, the mold used to form the hole 60 is also rectangular. Then, the mold is pulled out vertically upward. As a result, a hole 60 as shown in Figures 22(a) and (b) is formed in the road.

[0100] After the form is removed from the paved road, the plug 56 of the road surface light emitting unit 50, which contains the light emitting device, is inserted into the buried plug receptacle 62. This allows electricity to flow to the light source 14, enabling it to emit light. Then, once the road surface light emitting unit 50 is housed in the hole 60, the gap 64 between the road surface light emitting unit 50 and the hole 60 is filled with mortar or the like. In this way, the road surface light emitting unit 50 is fixed to the road, and a road marking device as shown in Figures 17 to 19 is completed.

[0101] 20, the mold used to form the holes is a rectangular prism with a parallelogram cross section, similar to the shape of the road surface light-emitting unit 40. As a result, the mold is pulled out in an upward diagonal direction, and the road surface light-emitting unit 40 is inserted in a downward diagonal direction, but the procedure for installing the road surface light-emitting unit 40 on the road and other methods can be the same as for the road surface light-emitting unit 50 shown in FIG.

[0102] In the above explanation, the road marking device is formed by embedding the road light emitting unit directly into the road. However, it is also possible to install the road light emitting unit in a flat plate-like unit such as an interlocking block or a precast concrete slab (collectively referred to as "road slab" below) and lay it on the road surface.

[0103] 23 is a diagram showing an example of the structure of a road plate in this embodiment, where (a) is a top view, (b) is a side cross-sectional view taken along line AA' shown in (a) and (c), and (c) is a bottom view. Here again, the case where the road surface light emitting unit 50 shown in FIG. 21 is used will be described as an example.

[0104] When the road slab 70 is made by solidifying concrete or the like, the road surface light emitting unit 50 may be placed in the formwork of the road slab 70, and then concrete or the like may be poured into the remaining part of the formwork and solidified. Alternatively, a mold of the same size may be placed in a flat formwork instead of the road surface light emitting unit 50, and concrete or the like may be poured into the remaining part of the formwork and solidified, and the mold may be pulled out and the road surface light emitting unit 50 may be incorporated in that position. In order to lay the road slab 70 incorporating the road surface light emitting unit 50 on the road, as in the case of directly burying the road surface light emitting unit 50 in the road, electric wires may be wired in advance near the surface of the roadbed, a plug receptacle may be provided at the position of the plug 56 of the road surface light emitting unit 50, and the plug 56 of the road surface light emitting unit 50 may be connected to the plug receptacle. Similarly, the road surface light emitting unit 40 shown in FIG. 21 may be incorporated into the road slab 70.

[0105] In the above description, one road surface light emitting unit 50 is incorporated, but a plurality of road surface light emitting units 50 may be incorporated into the road slab 70.

[0106] In addition, in the present embodiment, the case where electricity is supplied to the light source 14 using an electric wire has been described as an example, but if the road slab 70 is equipped with not only the road surface light-emitting unit 50 but also a power supply means such as a solar power generation panel or a battery, and electricity generated or stored on the road is used for the light source 14 of the road surface light-emitting unit 50 and further for the light source 14 of another road surface light-emitting unit 50, wiring on the roadbed side becomes unnecessary. In addition, for example, the wireless power supply described in Japanese Patent Application No. 2023-174082 (title of the invention: "Road Power Transmission Structure") by the same applicant as the present application may be used to supply power to the light source 14.

[0107] <Other> In the above embodiment, the light emitting device 10 has been described as being applied to a road marking device. However, the light emitting device may be installed in other locations. For example, the light emitting device may be embedded in the side wall of a building. In this case, there is no risk of pedestrians or vehicles tripping over the light emitting device 10, but it is preferable that the upper surface of the light emitting device 10 be formed as part of the planar wall surface of the building.

[0108] [Configuration of the present invention] Configuration 1: A light source means; a three-dimensional light guide formed of a first medium made of a transparent solid or liquid, the light guide being covered with a reflecting material at a boundary surface with a second medium having a refractive index relatively smaller than that of the first medium and at a surface on which an incident portion through which light from the light source means is incident is provided, except for the incident portion; Equipped with The light guide is The light from the light source means passing through the entrance portion is incident on the boundary surface at a predetermined incident angle according to a relative refractive index of the first medium with respect to the second medium, so that the refracted light at the boundary surface is emitted at a refraction angle at which the light reaches a predetermined target position, The reflected light at the boundary surface is reflected inside the light guide by the reflecting material to become incident light that is incident on the boundary surface at the predetermined incident angle, and the refracted light of the incident light at the boundary surface is radiated at a refraction angle that reaches the predetermined target position. A light emitting device characterized by: Configuration 2: 2. The light emitting device of configuration 1, wherein the interface forms part of a planar surface of an object when the light guide is embedded in the object. Configuration 3: 3. The light emitting device according to claim 1, wherein the light guide is formed of a prism having a parallelogram-shaped base, and one of the side surfaces of the prism is the boundary surface. Configuration 4: 4. The light emitting device according to any one of configurations 1 to 3, wherein the ratio of the base corresponding to the boundary surface in the parallelogram to the height is set according to the relative refractive index of the first medium with respect to the second medium. Configuration 5: 5. The light emitting device according to any one of configurations 1 to 4, wherein the light source means is disposed so as to suppress reflection of light irradiated toward the incident portion. Configuration 6: A light-emitting device according to any one of configurations 1 to 5, A road marking device characterized in that the boundary surface is installed so as to form a part of the road surface. [Explanation of symbols]

[0109] 10 Light emitting device, 12, 12a to 12d, 121, 121a, 121b, 122, 122a to 122h Light guide, 14 Light source, 16 Incident part, 18 Reflector, 20 Crosswalk, 21 Road surface (boundary surface), 22, 22a Incident light, 23, 23a Refracted light, 24 Reflected light, 30, 30a, 30b, 32, 32a, 32b, 34, 34a, 34b Road marking device, 40, 50 Road surface light emitting unit, 42, 44, 52, 54 Space, 46, 56 Plug, 60 Hole, 62 Plug receptacle, 64 Gap, 70 Road plate.

Claims

1. A light source means; a three-dimensional light guide formed of a first medium made of a transparent solid or liquid, the light guide being covered with a reflecting material at a boundary surface with a second medium having a refractive index relatively smaller than that of the first medium and at a surface on which an incident portion through which light from the light source means is incident is provided, except for the incident portion; Equipped with The light guide is The light from the light source means passing through the entrance portion is incident on the boundary surface at a predetermined incident angle according to a relative refractive index of the first medium with respect to the second medium, so that the refracted light at the boundary surface is emitted at a refraction angle at which the light reaches a predetermined target position, The reflected light at the boundary surface is reflected inside the light guide by the reflecting material to become incident light that is incident on the boundary surface at the predetermined incident angle, and the refracted light of the incident light at the boundary surface is radiated at a refraction angle that reaches the predetermined target position. A light emitting device characterized by:

2. 2. The light emitting device of claim 1, wherein the interface forms part of a planar surface of an object when the light guide is embedded in the object.

3. 2. The light emitting device according to claim 1, wherein the light guide is formed as a prism having a parallelogram-shaped base, and one of the side surfaces of the prism is the boundary surface.

4. 4. The light emitting device according to claim 3, wherein a ratio of a base side corresponding to the boundary surface to a height of the parallelogram is set according to a relative refractive index of the first medium with respect to the second medium.

5. 2. The light emitting device according to claim 1, wherein the light source means is disposed so as to suppress reflection of light irradiated toward the incident portion.

6. A light emitting device according to claim 1, A road marking device characterized in that the boundary surface is installed so as to form a part of the road surface.

Images