Light emitting device and road surface display device

Abstract

To provide a light-emitting device which efficiently emits light in a first direction and a second direction of a low elevation angle to a vehicle and does not make a driver feel an impact when the vehicle passes.SOLUTION: In the light emitting device, a light guide body 100 generates first refracted light and first reflection light at a ratio corresponding to a first incident angle by causing light from a light source X passing through an incident surface to be incident on a first boundary surface between a first medium and a second medium, the first boundary surface including an inclined surface formed by protruding from a road surface to a height equal to or lower than a 2mm. The first refracted light is radiated at a first refraction angle to reach a predetermined first target position, and after the first reflected light is reflected inside the light guide body 100, second refracted light is generated by making the first reflected light incident on a second boundary surface between the first medium and the second medium, and radiated at a second refraction angle to reach a predetermined second target position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a light emitting device and a road surface marking device used for illuminating roads and the like. [Background technology]

[0002] Light-emitting devices are installed on road centerlines, in the center of intersections, or at crosswalks, etc., and emit light to warn and guide the gaze of vehicle drivers and pedestrians. When emitting light from the road surface at a warning point such as a crosswalk toward drivers of vehicles approaching the point, the distance from the light-emitting point to the vehicle is several tens of times greater than the height from the road surface to the driver's eyes, so the light must be emitted at a low elevation angle. Road studs are an example of a product that emits light at a low elevation angle from the road surface. If multiple light sources are installed on both sides of a road stud, it is possible to emit light to both drivers of vehicles approaching the road stud and pedestrians on the crosswalk on the opposite side of the vehicle.

[0003] Prior art has disclosed various configurations using transparent light guide plates with a right-angled triangular cross section (Patent Document 1). When applying embodiment 4 of this document to a road, the right-angled triangle is positioned so that its hypotenuse is underground, its long side is on the road surface, and its short side is perpendicular to the road surface, and light is incident from the short side in a direction parallel to the road surface. In this case, the angle of incidence decreases as the light is repeatedly reflected by the hypotenuse and the road surface. When the angle of incidence on the road surface falls below the critical angle, some of the light is refracted onto the road at a low elevation angle. The light reflected within the light guide plate without refracting is reflected by the hypotenuse, then incident on the road surface at an even smaller angle of incidence, where some of it is refracted. Furthermore, embodiment 17 is configured to irradiate light in two different directions. When this configuration is applied to a road, the short sides of two light guide plates are joined to form a vertical cross section of an isosceles triangle with a small height-to-base ratio, and a light source is buried below the joint between the light guide plates and installed on the road. Furthermore, by cutting the top of the joint directly above the light source to create a low slope in the center and making the slope a mirror surface, the light that enters the slope from the light source is reflected into the light guide plate, ultimately enabling refraction at a low elevation angle. Note that although this configuration uses two light sources, refraction at a low elevation angle in two different directions is also possible with a single light source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-229703 Summary of the Invention [Problem to be solved by the invention]

[0005] In the prior art, road studs are used as products that emit light at a low elevation angle from the road surface, but road studs protrude from the road surface, and drivers feel the impact of bumps when passing over them. Also, light-emitting devices that use transparent light guide plates have the problem that the angle of incidence changes due to reflection within the light guide plate, making them susceptible to the effects of shape errors in the light path. [Means for solving the problem]

[0006] One aspect of the present invention is a light-emitting device comprising a light source and a light guide formed of a first medium and having an incident surface for light from the light source, wherein the light guide causes light from the light source that has passed through the incident surface to be incident on a first boundary surface between the first medium and the second medium at a first incident angle that is 6° or less different from the critical angle determined by the relative refractive index of the first medium with respect to a second medium having a refractive index different from that of the first medium, thereby generating first refracted light and first reflected light in a ratio that corresponds to the first incident angle, and radiating the first refracted light at a first refraction angle that reaches a predetermined first target position.

[0007] Here, it is preferable that the first boundary surface is provided on a protruding portion that protrudes from a road surface on which the light guide is arranged.

[0008] It is also preferable that the height of the protrusion from the road surface is 2 mm or less.

[0009] It is also preferable that the first reflected light is reflected inside the light guide so as to be incident on a second boundary surface between the first medium and the second medium at a second incident angle, and that second refracted light at the second boundary surface is emitted at a second refraction angle that reaches a predetermined second target position.

[0010] It is also preferable that the ratio between the amount of light from the light source and the amount of light directed to the first target position is set in accordance with an inclination angle, which is an angle formed between the first boundary surface and the road surface.

[0011] It is also preferable that the ratio of the amount of light that does not reach either the first target position or the second target position is set by the second refraction angle, which is the angle between the normal to the second boundary surface and the direction of the second target position.

[0012] Another aspect of the present invention is a road surface display device comprising the above-mentioned light-emitting device, wherein the light guide is embedded in the road surface so that the first boundary surface forms part of the road surface, and the light source is embedded below the light guide. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a light emitting device that emits a large amount of light at a low elevation angle and does not cause a shock when a vehicle passes by. Furthermore, by emitting light that is not emitted in the direction of a low elevation angle in a different direction, more efficient light emission is possible compared to conventional technology. [Brief explanation of the drawings]

[0014] [Figure 1] 1A to 1C are diagrams illustrating the principle of a light emitting device according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram showing the relationship between the refraction angle θT and the transmittance Tp of p-waves and the transmittance Ts of s-waves. [Figure 3] FIG. 10 is a diagram showing the difference in the optical path when light is emitted from a road surface and an inclined surface. [Figure 4] 2 is a cross-sectional view showing a configuration of a light guide included in the light emitting device according to the embodiment of the present invention. [Figure 5]1A and 1B are diagrams illustrating examples of arrangement of light emitting devices according to an embodiment of the present invention. [Figure 6] 2 is a cross-sectional view showing a configuration of a light guide included in the light emitting device according to the embodiment of the present invention. [Figure 7] 2 is a cross-sectional view showing a configuration of a light guide included in the light emitting device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Principle of the present embodiment] FIG. 1 is a diagram for explaining the principle of a light-emitting device according to an embodiment of the present invention. When light is used for road markings and is emitted from the road surface toward a driver of a vehicle heading toward a display point, the light must be emitted at a very small angle of elevation from the display point. When the height of the driver's eyes from the road surface is H [m] and the distance from the display point to the driver is L [m], the angle of elevation θ E The relationship between the two is expressed by equation (1). (Number 1) tanθ E =H / L (1)

[0016] For example, the elevation angle θ when L=40m and H=1.2m E can be expressed by equation (2). (Number 2) tanθ E =1.2 / 40 Elevation angle θ E =arctan 0.03=1.72° (2)

[0017] Small elevation angle θ E As a method of emitting light from the road surface, a groove is dug on the road surface to allow light to pass through, a light source is installed in the groove, and the light source is positioned at a small elevation angle θ E For example, if a light source with a size of 1.2 cm is placed in the groove, the elevation angle θ that satisfies the above condition is E To emit light from a solar panel, the required groove length is 40 cm. Therefore, if the groove becomes partially filled with dust and dirt over time, problems will arise, such as the light no longer radiating to the ground.

[0018] Also, as shown in Figure 1, a small elevation angle θ E One method of emitting light at high speed is to use the refraction of light. 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, and is buried in the road so that one side faces the road surface. When light is incident obliquely on the road surface from the light guide side, it is refracted by the road surface and emitted at a small elevation angle θ E It emits light.

[0019] In this case, the incident angle θ I , refraction angle θ T (=90°-θ E ) and the refractive index n of the light guide body, Snell's law of Equation (3) holds. (Number 3) n=sinθ T / sinθ I ···(3)

[0020] For example, when using polycarbonate with n=1.584, the elevation angle θ E =1.72°, i.e., the refraction angle θ T = 88.28°, light should be incident on the road surface under the condition of formula (4) based on Snell's law of formula (3). (Number 4) sinθ I =sinθ T / n=(sin88.28°) / 1.584=0.631 Incident angle θ I =arcsin0.631=39.13° (4)

[0021] The road surface display uses refracted light, and is aimed at the driver of a vehicle heading towards the display point at a very small elevation angle θ E , i.e., a large refraction angle θ T When light is emitted from the road surface, the intensity of the light received by the driver is weakened by two factors in addition to the long distance to the road marking: the light is spread by refraction, and the proportion of light that is refracted from the light guide side to the road surface is small.

[0022] Refraction angle θT is expressed by equation (5). (Number 5) θ T =arcsin(n sinθ I )····(5)

[0023] For example, the incident angle θ I Refraction angle θ at =39.13°±0.01° T are 87.91° (incident angle θ I =39.13°-0.01°) and 88.76° (when the incident angle θ I = 39.13° + 0.01°) Therefore, when light with an illumination angle of 0.02° is incident at an angle of θ I When the incident angle of the light is between 39.12° and 39.14°, the refracted light is T The illumination angle is 0.85°, from 87.91° to 88.76°, and the light is expanded by approximately 42 times due to refraction.

[0024] The latter point, where the proportion of light refracted by the light incident on the road surface from the light guide side is small, can be determined as follows. When light refracts at a boundary surface such as the road surface mentioned above, a portion of the light is reflected at the boundary surface. The refraction angle θ T When the angle is close to 90°, the ratio of reflected light is high and the ratio of refracted light is low. The ratio of the two can be calculated using the Fresnel formula shown below. Light is divided into p-waves and s-waves. In the case of Figure 1, the component perpendicular to the direction of light propagation within the plane is p-waves, and the component perpendicular to the plane is s-waves. In the following, refraction is referred to as transmission. The amplitude transmittance of p-waves, t p and amplitude reflectance r p , and the amplitude transmittance of s-waves t s and amplitude reflectance r s are expressed by the formulas (6) to (9), respectively. (Number 6) t p =2sinθ T cosθ I / {sin(θ I +θ T )cos(θ I -θ T )}···(6) (Number 7) r p=tan(θ I -θ T ) / tan(θ I +θ T )···(7) (Number 8) t s =2sinθ T cosθ I / sin(θ I +θ T )···(8) (Number 9) r s =-sin(θ I -θ T ) / sin(θ I +θ T )···(9)

[0025] Also, the transmittance of p-waves, T p and reflectance R p , s-wave transmittance T s and reflectance R s are expressed by formulas (10) to (13), respectively. (Number 10) T p =t p 2 tanθ I / tanθ T ···(10) (Number 11) R p =r p 2 ···(11) (Number 12) T s =t s 2 tanθ I / tanθ T ···(12) (Number 13) R s =r s 2 ···(13)

[0026] Figure 2 shows the refraction angle θ T and the p-wave transmittance T p and s-wave transmittance T sFIG. 2 shows the case where polycarbonate (refractive index n=1.584) is used as the light guide.

[0027] Refraction angle θ T and the p-wave transmittance T p , and the refraction angle θ T and s-wave transmittance T s According to the relationship, the refraction angle θ T In the vicinity of =90°, the refraction angle θ T With the increase of p and s-wave transmittance T s Both decrease rapidly and approach zero.

[0028] Refraction angle θ in polycarbonate T = 88.28°, the incident angle θ I = 39.13°, and the transmittance of p-waves T p =0.218, reflectance R p =0.782, s-wave transmittance T s = 0.093 and reflectance R s =0.907, which means that only 21.8% of the incident light is transmitted (refracted) as p-waves and only 9.3% as s-waves.

[0029] Increase the amount of light emitted toward the driver, in other words, increase the p-wave transmittance T p and s-wave transmittance T s In order to increase the angle of refraction, a part of the upper surface of the light guide is slightly protruded from the road surface, and an inclined surface is provided on the upper surface of the light guide, and the light from the light guide is refracted at the inclined surface and transmitted onto the road, thereby increasing the angle of refraction θ T It is preferable to make the value of .lambda. small.

[0030] However, it is preferable to make the amount by which a portion of the upper surface of the light guide protrudes from the road surface as small as possible. For example, it is preferable to make the amount by which a portion of the upper surface of the light guide protrudes from the road surface 2 mm or less. This makes it possible to reduce the impact on the vehicle when the vehicle passes over the protruding portion from the road surface, and to prevent a deterioration in the driver's driving feel.

[0031] Refraction angle θT In the vicinity of =90°, the refraction angle θ T With the increase of p and s-wave transmittance T s In other words, the refraction angle θ T With the decrease of p and s-wave transmittance T s Both will increase sharply.

[0032] For example, as shown in FIG. 3(b), the upper surface of the light guide is protruded from the road surface by a width of 10 mm, and the light guide is tilted at an inclination angle θ of 11° with respect to the road surface. slope When the projection is placed on the slope, the maximum height from the road surface is 10tan11° = 1.9 [mm]. When emitting light from the slope toward the driver, the elevation angle θ E is expressed by Equation (14). (Number 14) Elevation angle θ E =90°-refractive angle θ T -Inclination angle θ slope ···(14)

[0033] Therefore, the refraction angle θ T is the tilt angle θ slope Specifically, the angle of elevation θ E = 1.72°, the refraction angle θ T The angle of inclination θ is 88.28° when refracted from the road surface. slope It is 11 minutes lower at 77.28°.

[0034] From equation (4), the angle of incidence θ I = 38.01°, and the transmittance of p-waves T p =0.851 and s-wave transmittance T s =0.510. In other words, the transmittance is four times higher than when refracted from the road surface, and the amount of light at low elevation angles can be increased.

[0035] In the case of Figure 3(b), the reflectivity R of the p-wave is calculated based on Equations (11) and (13). p = 0.149 and s-wave reflectivity R s=0.490, and part of the light incident on the inclined surface is reflected into the light guide. This reflected light can be used to irradiate light in a different direction.

[0036] For example, if a road surface light-emitting device installed next to a crosswalk emits light at a low angle in the direction of vehicles approaching the crosswalk, it is difficult for drivers to intuitively sense the target of the warning with just the light, but if the light is also emitted in the direction of pedestrians crossing the street, it becomes easier for drivers to notice the pedestrians.

[0037] [Example] Fig. 4 is a diagram showing an example of the configuration of a light guide 100 included in the light emitting device of this embodiment. Fig. 4 shows a cross-sectional view of the light guide 100, and the light guide 100 has a thickness in the depth direction of the paper.

[0038] The light guide 100 reflects light inside and emits the light at a desired angle from the road surface. The light guide 100 is installed above the light source X of the light emitting device and is embedded in the road surface when in use. FIG. 5 shows an example of the arrangement of the light emitting device 300 on a road. The light emitting device 300 is, for example, embedded in the road surface near a crosswalk.

[0039] The light guide 100 is made of, for example, polycarbonate (refractive index n=1.584). The outer shape of the light guide 100 is designed with a specific angle and shape for the purpose of efficient incidence and emission of light.

[0040] The upper surface of the light guide 100 forms part of the road surface. Therefore, it is preferable that the thickness of the light guide 100 in the embedding direction is set to a level that will not be damaged by vehicles 200 passing over the road surface. For example, if the light guide 100 is made of polycarbonate, it is preferable that the thickness of the light guide 100 in the vertical direction be 20 mm or more. This allows the light guide 100 to have sufficient mechanical strength to prevent damage to the light guide 100 or the light source X arranged below it when a vehicle passes over it.

[0041] The upper surface of the light guide 100 plays an important role in efficiently transmitting light toward the vehicle 200 and toward pedestrians walking on the crosswalk. Nearly half of the upper surface of the light guide 100 on the vehicle side (the right side in Figure 4) forms the road surface, and a protrusion 10 with an inclined surface continues from this surface. The protrusion 10 is a part of the upper surface of the light guide 100 that protrudes from the road surface. It is preferable that the height of the protrusion 10 from the road surface be 2 mm or less.

[0042] In this embodiment, the inclination angle θ of the protrusion 10 with respect to the road surface is slope is 11°. The inclination angle θ slope are designed to refract light efficiently and are set to emit a large amount of light at a low elevation angle toward the driver of the vehicle 200.

[0043] The bottom surface of the light guide 100 is provided with a cut surface 12 for allowing light from the light source X to enter the light guide 100. Light from the light source X is perpendicularly incident on the cut surface 12. This ensures high light transmittance at the cut surface 12. This design allows light to efficiently enter the light guide 100, undergo necessary reflection, and then exit from the inclined surface of the protrusion.

[0044] The vehicle-side (right side of Figure 4) of both sides and the bottom of the light guide 100 are mirrored, and by reflecting the light inside, the light travels efficiently within the light guide 100 and is emitted in a predetermined direction.

[0045] Inclination angle θ from the road surface slope On the inclined surface inclined by (marked × in FIG. 4)=11°, an incident angle θ I1 (The circle in Figure 4 indicates the first incidence on the top surface.) = 38.01°. Here, the incident angle θ I1 is the elevation angle θ of the refracted light relative to the road surface E , the inclination angle θ of the inclined surface slope and a value determined by the relative refractive index n of the medium constituting the light guide 100 relative to the refractive index of the medium on the road surface, i.e., air, and typically the difference from the critical angle determined by the relative refractive index n is 6° or less.

[0046] The optical path of light until it enters the inclined surface is as follows: Light from the light source X enters the cut surface 12 on the bottom surface and passes through the light guide 100. The angle θ of the cut surface 12 cut 49.01° (marked + in Figure 4). Angle θ cut = angle of incidence θ I1 +tilt angle θ slope ), the incident angle θ I0 = refraction angle θ T0 =0°, and light from the light source X can be incident perpendicularly on the cutting surface 12. Therefore, light can be transmitted through the light guide 100 with a very high transmittance.

[0047] Light transmitted from the light source into the light guide 100 is incident on the left side of the light guide 100 at an angle θ cut = 40.99° (marked △ in FIG. 4 ) and reflected, the light is incident on the inclined surface of the protrusion 10 at an angle θ cut -Inclination angle θ slope =38.01° (marked with a circle in Figure 4).

[0048] The light path after being incident on the inclined surface of the protrusion 10 is as follows: A part of the incident light is refracted at a refraction angle θ T1 =77.28° (marked ● in Figure 4), elevation angle θ relative to the road surface E1 =1.72°(=90°-tilt angle θ slope -refractive angle θ T1 , Equation (14)). The transmittance T of the p-wave of refracted light is p1 =0.851, s-wave transmittance T s1 =0.510. In addition, the reflectivity R of the remaining p-waves on the inclined surface of the protrusion 10 is p1 =0.149, s-wave reflectivity R s1 =0.490, the light corresponding to the incident angle θ I1 It is reflected at an angle of reflection equal to 38.01° (marked with a circle in Figure 4).

[0049] The light reflected from the inclined surface of the protrusion 10 is incident on the mirror surface on the bottom at an angle of θ I1 -Inclination angle θ slope = 27.01° (marked ◇ in Figure 4), and after being incident and reflected on the right side, it also reaches the upper surface that constitutes the road surface at an incident angle of θ I2(2 indicates the second incidence on the top surface) = Incident angle θ I1 -Inclination angle θ slope = 27.01°. Then, according to Snell's law (Equation (3)), the refraction angle θ T2 = 46.00°, i.e., elevation angle θ E2 =90°-refractive angle θ T2 = 44.00°, the refracted light is transmitted to the crosswalk side of the road. The refracted light is directed in a direction where the distance L from the light guide 100 of the light emitting device and the height H from the road surface are approximately equal (refraction angle θ T2 Therefore, if the distance from the light guide 100 of the light emitting device to a pedestrian on a crosswalk is approximately equal to the height of the pedestrian, the light will be emitted toward the pedestrian.

[0050] The shape of the light guide 100 is such that the elevation angle θ E1 is designed to be the target value. From equation (14), the elevation angle θ E1 is the tilt angle θ slope and the refraction angle θ T1 Also, from equation (3), the refraction angle θ T1 is the refractive index n of the light guide material and the incident angle θ I1 Therefore, when light from the light source X is transmitted through the light guide 100 perpendicular to the cutting surface 12, the incident angle θ I1 = angle θ cut -Inclination angle θ slope and the elevation angle θ E1 and the angle θ from the refractive index n of the material of the light guide 100 cut and the inclination angle θ slope is determined.

[0051] Next, the elevation angle θ of the second target relative to the road surface E2 The shape of the light guide 100 is designed so that the incident angle θ is a target value. When the lower surface is parallel to the road surface and light is emitted from the upper surface that constitutes the road surface and is not the protrusion 10 toward the second target, as described above, I2 = angle of incidence θ I1 -Inclination angle θ slope Then, from equation (3), the refraction angle θ T2 (=90°-elevation angle θ E2) is the refractive index n of the material of the light guide 100 and the incident angle θ I2 Since it is a function of angle θ cut and the inclination angle θ slope Once the incident angle θ I1 is determined, and the incident angle θ I2 and refraction angle θ T2 , elevation angle θ E2 is also decided.

[0052] FIG. 6 shows an example of a configuration in which an inclined surface 14 is provided on the lower surface of the light guide 100. In FIG.

[0053] Inclination angle θ of the lower inclined surface slopel For the incident angle θ I2 = angle of incidence θ I1 -Inclination angle θ slope -2 inclination angle θ slopel and the inclination angle θ of the additional inclined surface 14 slopel By appropriately setting the incident angle θ I2 , refraction angle θ T2 , and the elevation angle θ E2 can be set as the target value.

[0054] The light refracted the first time from the upper surface of the light guide 100 is emitted to a first target (the driver of the vehicle 200), the light refracted the second time is emitted to a second target (a pedestrian on the crosswalk), and the light reflected the second time is the light lost that does not reach these targets. The ratio of the amount of light between the first target and the second target and the loss is expressed by Equation (15) using the transmittance T and reflectance R described above. (Number 15) T w1 :R w1 T w2 :R w1 R w2 ···(15) Here, the subscript w indicates p-wave or s-wave, and the subscripts 1 and 2 indicate the first and second incidences on the top surface, respectively.

[0055] In the case of the light guide 100 shown in FIG. 4, the transmittance T p1 =0.851 and s-wave transmittance T s1 =0.510, and the p-wave reflectivity R p1= 0.149 and s-wave reflectivity R s1 =0.490. For the second incidence, the angle of incidence θ I2 = 27.01° and refraction angle θ T2 = 46.00°, and from equations (6) to (13), the transmittance of p-waves T p2 = 0.989 and s-wave transmittance T s2 =0.884, and the p-wave reflectivity R p2 =0.011 and s-wave reflectivity R s2 =0.116 is obtained.

[0056] Therefore, based on equation (15), the light intensity ratio for p-waves is 0.851:0.149×0.989:0.149×0.011 = 0.851:0.147:0.002, and for s-waves it is 0.510:0.490×0.884:0.490×0.116 = 0.510:0.433:0.057. The actual light intensity ratio is the average of p-waves and s-waves, and is light intensity to first target:light intensity to second target:light intensity lost = 0.680:0.290:0.030.

[0057] As mentioned above, the larger the refraction angle, the wider the refracted light becomes, so it is desirable that the light amount of the first target with a larger refraction angle is greater than that of the second target. T2 If the second goal is set to reduce the transmittance of p-waves, T p2 and s-wave transmittance T s2 becomes larger, and the reflectivity R of the p-wave increases. p2 and s-wave reflectivity R s2 Therefore, the loss of light can be reduced.

[0058] To change the light intensity ratio to the first target, change the tilt angle θ slope (The mark "x" in Figure 4) can be changed. The direction of light transmission to the first target, i.e., the elevation angle θ of the first target relative to the road surface E1 Without changing the tilt angle θ slope When changing the tilt angle θ slope If you increase the elevation angle θ E =90°-refractive angle θ T -Inclination angle θ slopeFrom the relationship of (Equation (14)), the refraction angle θ T1 This reduces the transmittance of p-waves, T p1 and s-wave transmittance T s1 becomes larger, and the light intensity ratio to the first target can be increased. In this case, the light intensity ratio to the second target decreases. Conversely, if the light intensity ratio to the first target is decreased and the light intensity ratio to the second target is increased, the inclination angle θ slope can be made smaller.

[0059] 4 and 6, light from light source X enters in a direction away from the vehicle 200, is reflected by the side surface, changes direction toward the vehicle 200, and then enters the inclined portion of the protrusion 10 on the upper surface. In contrast, if the ratio of width to height of the light guide 100 can be increased, as shown in FIG. 7, the light guide 100 may be configured so that light from light source X directly enters the inclined portion of the protrusion 10 on the upper surface. The light guide 100 having such a configuration has the advantage that even if the side surface of the light guide 100 is misaligned with respect to the vertical direction, the angle of incidence on the inclined portion of the protrusion 10 on the upper surface is not affected by the misalignment.

[0060] As described above, the light emitting device of this embodiment is configured to emit light from the light guide 100 in two predetermined directions. This allows for highly efficient light emission toward the driver of the vehicle 200 and pedestrians on the crosswalk. Furthermore, the amount of protrusion from the road surface is small, thereby minimizing the impact on the running of the vehicle 200. That is, since the height of the protrusion 10 from the road surface is very low (2 mm or less), it is possible to emit a large amount of light at a low elevation angle and reduce the impact felt by the driver when the vehicle 200 passes over the protrusion 10.

[0061] [Configuration of the present invention] [Configuration 1] A light source and a light guide formed of a first medium and having an incident surface for light from the light source; A light emitting device comprising: The light guide is light from the light source that has passed through the incident surface is incident on a first interface between the first medium and the second medium at a first incident angle that is 6° or less from a critical angle determined by a relative refractive index of the first medium with respect to a second medium having a refractive index different from that of the first medium, thereby generating first refracted light and first reflected light in a ratio according to the first incident angle; A light emitting device that emits the first refracted light at a first refraction angle that reaches a predetermined first target position. [Configuration 2] The light-emitting device according to configuration 1, The light emitting device is characterized in that the first boundary surface is provided on a protruding portion that protrudes from a road surface on which the light guide is arranged. [Configuration 3] The light-emitting device according to configuration 2, A light emitting device characterized in that the height of the protrusion from the road surface is 2 mm or less. [Configuration 4] The light emitting device according to any one of configurations 1 to 3, a light emitting device characterized in that the first reflected light is reflected inside the light guide body so as to be incident on a second boundary surface between the first medium and the second medium at a second incident angle, and a second refracted light at the second boundary surface is emitted at a second refraction angle at which the second refracted light reaches a predetermined second target position. [Configuration 5] The light-emitting device according to configuration 4, A light emitting device characterized in that the ratio of the light intensity of the light source to the light intensity at the first target position is set according to an inclination angle, which is the angle between the first boundary surface and the road surface. [Configuration 6] The light-emitting device according to configuration 4 or 5, A light emitting device characterized in that the ratio of the amount of light that does not reach either the first target position or the second target position is set by the second refraction angle, which is the angle between the normal to the second boundary surface and the direction of the second target position. [Configuration 7] A light-emitting device according to any one of configurations 1 to 6 is provided, A road surface display device characterized in that the light guide is embedded in the road surface so that the first boundary surface and the second boundary surface form part of the road surface, and the light source is embedded below the light guide. [Explanation of symbols]

[0062] 10 protrusion, 12 cutting surface, 14 inclined surface, 100 light guide, 200 vehicle, 300 light emitting device, X light source.

Claims

1. A light source and a light guide formed of a first medium and having an incident surface for light from the light source; A light emitting device comprising: The light guide is light from the light source that has passed through the incident surface is incident on a first interface between the first medium and the second medium at a first incident angle that is 6° or less from a critical angle determined by a relative refractive index of the first medium with respect to a second medium having a refractive index different from that of the first medium, thereby generating first refracted light and first reflected light at a ratio according to the first incident angle; A light emitting device that emits the first refracted light at a first refraction angle that reaches a predetermined first target position.

2. 2. The light emitting device according to claim 1, The light emitting device, characterized in that the first boundary surface is provided on a protruding portion that protrudes from a road surface on which the light guide is arranged.

3. 3. The light emitting device according to claim 2, A light emitting device characterized in that the height of the protrusion from the road surface is 2 mm or less.

4. The light emitting device according to any one of claims 1 to 3, a light emitting device characterized in that the first reflected light is reflected inside the light guide so as to be incident on a second boundary surface between the first medium and the second medium at a second incident angle, and a second refracted light at the second boundary surface is emitted at a second refraction angle at which it reaches a predetermined second target position.

5. 5. The light emitting device according to claim 4, A light emitting device, characterized in that the ratio of the light intensity of the light source to the light intensity at the first target position is set according to an inclination angle, which is the angle between the first boundary surface and the road surface.

6. 5. The light emitting device according to claim 4, A light emitting device characterized in that the ratio of the amount of light that does not reach either the first target position or the second target position is set by the second refraction angle, which is the angle between the normal to the second boundary surface and the direction of the second target position.

7. A light emitting device according to claim 1, A road surface display device, characterized in that the light guide is embedded in the road surface so that the first boundary surface forms a part of the road surface, and the light source is embedded below the light guide.

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