Optical member

Abstract

To provide an optical member capable of improving the visibility of sight of a dead angle area.SOLUTION: An optical member 10 comprises a transparent material 20. The transparent material comprises: a first prism 70 including an incidence surface 72 which ambient light Lo enters from a dead angle area and a light-blocking surface 75 connected to the incidence surface 72 and which the ambient light Lo enters; a first reflection surface 31 reflecting light from the incidence surface 72; a second reflection surface 32 reflecting light reflected by the first reflection surface 31; and a second prism 40 including an emission surface 42 emitting light from the incidence surface 72 and light reflected by the second reflection surface 32 to the outside and a surface 45 intersecting with and connected to the emission surface 42 and receiving light from the light-blocking surface 75. The light-blocking surface 75 has a rough surface, and surface roughness of the rough surface is greater than surface roughness of the incidence surface 72.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present disclosure relates to an optical member.

Background Art

[0002] Conventionally, as described in Patent Document 1, a blind spot assisting device including a semi-transmissive mirror, a mirror, a light-transmissive member, and a plurality of prisms is known. The semi-transmissive mirror is provided on the viewer side. The mirror reflects light to the semi-transmissive mirror. The light-transmissive member is provided between the semi-transmissive mirror and the mirror. The plurality of prisms are provided between the semi-transmissive mirror and the viewer. Each prism has a light-shielding layer on a surface that does not face the light incident surface of the light-transmissive member. The light incident from the viewer side is blocked by this light-shielding layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the study by the inventors, in the configuration of the blind spot assisting device described in Patent Document 1, in addition to the light incident from the viewer side becoming stray light, the light that passes through the incident surface of the light-transmissive member and is reflected at the interface between the prism and the light-shielding layer passes through the exit surface of the light-transmissive member and becomes stray light. This stray light reduces the visibility of the scene in the blind spot area.

[0005] An object of the present disclosure is to provide an optical member that improves the visibility of the scene in the blind spot area.

Means for Solving the Problems

[0006] The invention according to claim 1 includes a first prism (70) having an incident surface (72) on which external scene light (Lo) enters from a blind spot region and a light shielding surface (75) that is connected to the incident surface and on which the external scene light enters, a first reflection surface (31) that reflects light from the incident surface, a second reflection surface (32) that reflects the light reflected by the first reflection surface, a second prism (40) having an emission surface (42) that emits the light from the incident surface and the light reflected by the second reflection surface to the outside and a surface (45) that intersects and is connected to the emission surface and on which the light from the light shielding surface enters, and a light guide body (20) having the same. The light shielding surface includes a rough surface (753), and the surface roughness of the rough surface is larger than the surface roughness of the incident surface.

[0007] Accordingly, when the external scene light enters the light shielding surface, the incident light is scattered by the rough surface. For this reason, the amount of light traveling from the light shielding surface to the surface connected to the emission surface decreases. Therefore, it becomes difficult for the light from the light shielding surface to reach the surface connected to the emission surface. Thus, since it becomes difficult for the light from the light shielding surface to be reflected by the surface connected to the emission surface, the light reflected by the surface connected to the emission surface becomes difficult to reach the emission surface. For this reason, since it becomes difficult for stray light to reach the viewer, the visibility of the scene in the blind spot region is improved.

[0008] Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0009]

Figure 1

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Figure 16

Figure 17

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals, and the description thereof will be omitted.

[0011] (First Embodiment) The optical member 10 of the present embodiment is used, for example, in the vehicle 1. As shown in FIG. 1, this vehicle 1 includes a steering wheel 2, a front window 3, a side window 4, a pillar 5, an optical member 10, and the like. The optical member 10 is attached to the pillar 5, for example, and guides the external light Lo from the area that becomes a blind spot due to the pillar 5 to the occupant of the vehicle 1, so that the occupant of the vehicle 1 can visually recognize the scenery in the blind spot area. Note that the occupant of the vehicle 1 corresponds to the viewer.

[0012] Specifically, as shown in FIGS. 2 to 4, the optical member 10 includes a light guide 20 and a light shielding layer 60. In FIGS. 3, 4 and the cross-sectional views described later, the cross-sectional hatching of the optical member 10 is omitted for easy understanding.

[0013] The light guide 20 is formed of a light-transmissive material such as a resin material like polyethylene terephthalate, polycarbonate, polyethylene, and acrylic, or glass. Further, the light guide 20 has an incident surface 25, a first reflection surface 31, a second reflection surface 32, and a plurality of prisms 40.

[0014] The incident surface 25 is the surface on which the outside scene light Lo is incident. The first reflection surface 31 is disposed on the passenger side of the vehicle 1 and intersects the incident surface 25. Further, on the first reflection surface 31, the light from the incident surface 25 is reflected. The second reflection surface 32 is connected to the opposite side of the incident surface 25 from the first reflection surface 31 and is parallel to the first reflection surface 31. Furthermore, on the second reflection surface 32, the light reflected by the first reflection surface 31 is reflected.

[0015] Here, the direction of the normal line passing through the first reflection surface 31 is defined as the normal direction Dn. And the incident surface 25 is inclined with respect to the normal direction Dn. Further, the incident surface angle Asi, which is the inclination angle of the incident surface 25 with respect to the normal direction Dn, is an acute angle. Also, let the refractive index of the light guide 20 be n1. Also, let the refractive index of the external medium of the light guide 20 be n2. Furthermore, let the incident angle when the light from the incident surface 25 is reflected by the first reflection surface 31 and the incident angle when the light reflected by the first reflection surface 31 is reflected by the second reflection surface 32 be θi. At this time, the light guide 20 is formed so as to satisfy the following relational expression (1). Thereby, even if the light guide 20 does not have a semi-transmissive mirror, the light from the incident surface 25 is totally reflected by the first reflection surface 31 and the second reflection surface 32.

[0016] sinθi≧n2 / n1 ···(1)

[0017] Next, the prism 40 is formed by molding, cutting, blasting, etc. and combinations thereof during the formation of the light guide 20. Further, the prism 40 protrudes from the first reflection surface 31 and is formed in a triangular prism shape. Furthermore, the prisms 40 are arranged at predetermined intervals. As a result, the first reflection surfaces 31 are arranged at predetermined intervals in the arrangement direction of the prisms 40. The prism 40 includes a prism emission surface 42 and a prism light shielding surface 45.

[0018] The prism emission surface 42 is connected to the first reflection surface 31. Also, the prism emission surface 42 is parallel to the incident surface 25. For this reason, the prism emission surface 42 is inclined at an incident surface angle Asi with respect to the normal direction Dn. Furthermore, the root mean square height of the prism emission surface 42 is, for example, 0.005 μm. Light from the incident surface 25 and light reflected by the second reflection surface 32 are emitted from the prism emission surface 42. The root mean square height is measured by a measurement method compliant with, for example, ISO25178 and JISB0601.

[0019] As will be described later, the prism light shielding surface 45 is a surface on which light from the incident surface 25 and light reflected by the second reflection surface 32 are incident, and blocks this incident light. Thereby, the prism light shielding surface 45 suppresses the light from becoming stray light GL. Specifically, the prism light shielding surface 45 intersects and is connected to the prism emission surface 42. Also, as shown in FIG. 4, the prism light shielding surface 45 includes a flat surface 451 and a rough surface 453.

[0020] The flat surface 451 is connected to the first reflection surface 31. Furthermore, the root mean square height of the flat surface 451 is, for example, 0.005 μm.

[0021] The rough surface 453 is connected to the prism emission surface 42 and the flat surface 451. Also, the root mean square height of the rough surface 453 is higher than the root mean square height of the prism emission surface 42 and the flat surface 451. Therefore, the surface roughness of the rough surface 453 is greater than the surface roughness of the prism emission surface 42 and the flat surface 451. Furthermore, the root mean square height of the rough surface 453 is 0.1 μm or more. Also, the ratio of the area of the rough surface 453 to the area of the prism light-shielding surface 45 is 50% or more. In FIG. 4, the ratio of the area of the rough surface 453 to the area of the prism light-shielding surface 45 is set to 50%. Also, where the ratio of the area of the rough surface 453 to the area of the prism light-shielding surface 45 is 50% or more, the ratio of the width of the rough surface 453 to the width of the prism light-shielding surface 45 may be 50% or more.

[0022] The light-shielding layer 60 is a light-absorbing film that absorbs 99% or more of light. Also, the light-shielding layer 60 is formed, for example, by coating, printing, vapor deposition, etc. with a black resin. Furthermore, the light-shielding layer 60 covers the entire surface of each prism light-shielding surface 45. Thereby, as will be described later, the light-shielding layer 60 blocks the light SL incident from the passenger side of the vehicle 1 toward the prism light-shielding surface 45. Note that the light-shielding layer 60 covers the entire surface of the prism light-shielding surface 45, but is not limited thereto, and may cover at least a part of the rough surface 453. Also, the light-shielding layer 60 is formed of a black resin, but is not limited to the black resin, and may be formed of, for example, a metal.

[0023] As described above, the optical member 10 of the first embodiment is configured. In the optical member 10 of the present embodiment, the scene in the blind spot area due to the pillar 5 is visible to the passenger of the vehicle 1, and the visibility thereof is improved. Next, with reference to FIG. 5, the visibility of the scene in the blind spot area will be described.

[0024] For example, when the external scene light Lo is incident on the incident surface 25 at the incident angle θo, it is refracted in the light guide 20 to become the incident light Li. Note that the incident angle θo is the angle formed by the traveling direction of the external scene light Lo and the normal direction Dn.

[0025] Furthermore, a part of the incident light Li travels toward the first reflection surface 31 at the incident angle θi and reaches the first reflection surface 31. The incident light Li that has reached the first reflection surface 31 is totally reflected by the first reflection surface 31 and becomes the first reflected light Lr1. Also, the first reflected light Lr1 travels toward the second reflection surface 32 at the incident angle θi and reaches the second reflection surface 32. The first reflected light Lr1 that has reached the second reflection surface 32 is totally reflected by the second reflection surface 32 and becomes the second reflected light Lr2. Furthermore, the second reflected light Lr2 travels toward the prism emission surface 42 and reaches the prism emission surface 42. The second reflected light Lr2 that has reached the prism emission surface 42 is emitted from the prism emission surface 42 at the emission angle θu that is the same as the incident angle θo and becomes the emitted light Lu. Then, when the emitted light Lu travels toward and reaches the occupant of the vehicle 1, the scene in the blind spot area due to the pillar 5 is visually recognized. Note that the incident angle θi is the angle formed between the traveling direction of the incident light Li and the normal direction Dn. The emission angle θu is the angle formed between the traveling direction of the emitted light Lu and the normal direction Dn. Also, since Asi < π / 2 - θi is satisfied, the incident angle θi is larger than the incident angle θo. Thereby, the incident light Li travels toward a wide range of the first reflection surface 31. Furthermore, the inclination angle of the prism light shielding surface 45 with respect to the normal direction Dn is equal to or greater than the incident angle θo. For this reason, since the emitted light Lu is emitted to the outside without being blocked by the prism light shielding surface 45, the loss of the light amount in emission is reduced.

[0026] Also, a part of the incident light Li travels toward the prism emission surface 42 and reaches the prism emission surface 42. The incident light Li that has reached the prism emission surface 42 is emitted from the prism emission surface 42 at the emission angle θu that is the same as the incident angle θo and becomes the emitted light Lu. Then, when the emitted light Lu travels toward and reaches the occupant of the vehicle 1, the scene in the blind spot area due to the pillar 5 is visually recognized.

[0027] As described above, the scene in the blind spot area due to the pillar 5 is visually recognized by the occupant of the vehicle 1. Next, an improvement in the visibility of the scene in the blind spot area will be described.

[0028] Here, in order to explain the improvement in visibility by the optical member 10, a comparative optical member 900 as a comparative example will be described. As shown in FIGS. 6 and 7, the comparative optical member 900 includes a comparative light guide 920 and a comparative light shielding layer 960. The comparative light guide 920 corresponds to the light guide 20 and has a comparative incident surface 925, a comparative first reflection surface 931, a comparative second reflection surface 932, and a plurality of comparative prisms 940. The comparative incident surface 925 corresponds to the incident surface 25. The comparative first reflection surface 931 corresponds to the first reflection surface 31. The comparative second reflection surface 932 corresponds to the second reflection surface 32. The comparative prism 940 has a comparative emission surface 942. The comparative emission surface 942 corresponds to the prism emission surface 42. The comparative light shielding layer 960 corresponds to the light shielding layer 60. Therefore, these detailed descriptions will be omitted.

[0029] In addition, the comparative prism 940 has a comparative flat surface 945 in addition to the comparative emission surface 942. The comparative flat surface 945 is connected to the first reflection surface 31 and the comparative emission surface 942 and is covered with the comparative light shielding layer 960. Further, the root mean square height of the comparative flat surface 945 is equal to or less than the root mean square height of the comparative emission surface 942.

[0030] Also, here, the refractive index of the comparative light guide 920 is set to 1.49. The refractive index of the comparative light shielding layer 960 is set to 1.59. At this time, the refractive index difference between the comparative light guide 920 and the comparative light shielding layer 960 is 0.1. And in this case, when the external scene light Lo is incident on the incident surface 25, the light from the comparative incident surface 925 and the light reflected by the comparative second reflection surface 932 may be reflected by the comparative flat surface 945. At this time, when the reflectance R reflected by the comparative flat surface 945 is calculated using Fresnel's reflection formula, as shown in FIGS. 7 and 8, as the incident angle θs of the light reaching the comparative flat surface 945 increases, the reflectance R increases. Further, for example, when the incident angle θs is 86°, the reflectance R also becomes 40%. Here, the reflectance R is the sum of the amplitude reflectance of the p-wave of the light and the amplitude reflectance of the s-wave of the light.

[0031] Furthermore, the light reflected by the comparison flat surface 945 travels to and reaches the comparison emission surface 942. When this reached light is emitted from the comparison emission surface 942 and travels toward the occupant of the vehicle 1, it becomes stray light GL. Due to this stray light GL, the visibility of the scenery in the blind spot area is reduced.

[0032] On the other hand, in the optical member 10 of the present embodiment, the surface roughness of the rough surface 453 is larger than the surface roughness of the prism emission surface 42. As a result, as shown in FIG. 9, when the light from the incident surface 25 and the light reflected by the second reflection surface 32 enter the prism light shielding surface 45, the incident light is scattered by the rough surface 453 of the prism light shielding surface 45. For this reason, the amount of light traveling from the prism light shielding surface 45 toward the prism emission surface 42 decreases. Therefore, the light reflected by the prism light shielding surface 45 is less likely to reach the prism emission surface 42. Thus, since the stray light GL is less likely to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0033] Also, the optical member 10 of the first embodiment exhibits the following effects.

[0034] [1-1] The prism light shielding surface 45 includes a flat surface 451 and a rough surface 453. Also, the ratio of the area of the rough surface 453 to the area of the prism light shielding surface 45 is 50% or more. As a result, since the area of the rough surface 453 included in the prism light shielding surface 45 is equal to or greater than the area of the flat surface 451, the probability that the light from the incident surface 25 and the light reflected by the second reflection surface 32 are reflected by the rough surface 453 increases. For this reason, the light incident on the prism light shielding surface 45 is likely to be scattered, so the amount of light traveling from the prism light shielding surface 45 toward the prism emission surface 42 is likely to decrease. Therefore, the light reflected by the prism light shielding surface 45 is less likely to reach the prism emission surface 42. Thus, since the stray light GL is less likely to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0035] [1-2]Here, the refractive index of the light guide 20 is set to 1.49, and the refractive index of the light shielding layer 60 is set to 1.59. At this time, the refractive index difference between the light guide 20 and the light shielding layer 60 is 0.1. Also, assume that either the light from the incident surface 25 or the light reflected by the second reflection surface 32 is incident on the rough surface 453 at an incident angle θs = 86°. In this case, as shown in FIG. 10, as the root mean square height of the rough surface 453 increases, the reflectance R at the prism light shielding surface 45 rapidly decreases. Also, when the root mean square height of the rough surface 453 is 0.005 μm, the reflectance R is 40%. Furthermore, when the root mean square height of the rough surface 453 is 0.1 μm or more, the reflectance R at the prism light shielding surface 45 is 20% or less, which is less than half of that when the root mean square height of the rough surface 453 is 0.005 μm.

[0036] Therefore, in the optical member 10, the root mean square height of the rough surface 453 is 0.1 μm or more. As a result, the reflectance R becomes less than half compared to the case where the rough surface 453 is a smooth surface. For this reason, it becomes difficult for the light reflected by the prism light shielding surface 45 to reach the prism light emitting surface 42. Therefore, since the stray light GL becomes difficult to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0037] [1-3]The optical member 10 further includes a light shielding layer 60 corresponding to the light shielding portion. The light shielding layer 60 covers the rough surface 453 and blocks the light from the outside of the light guide 20. As a result, since the light from the outside of the light guide 20 on the prism 40 side is blocked, as shown in FIG. 11, it is possible to suppress the light SL from the outside of the light guide 20 on the prism 40 side from becoming stray light.

[0038] In addition, due to the rough surface 453 whose root mean square height is higher than the prism emission surface 42, the incident angle of the light reaching the rough surface 453 becomes microscopically smaller. Therefore, the light reaching the rough surface 453 is refracted and tends to travel toward the light shielding layer 60. Since the light that has traveled to the light shielding layer 60 is blocked by the light shielding layer 60, the amount of light traveling from the prism light shielding surface 45 toward the prism emission surface 42 tends to decrease. Therefore, it becomes difficult for the light reflected by the prism light shielding surface 45 to reach the prism emission surface 42. Thus, since the stray light GL is less likely to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0039] [1-4] The light shielding layer 60 is a light absorption film that absorbs light. Thereby, the light from the outside of the light guide 20 on the prism 40 side is absorbed. For this reason, the light from the outside of the light guide 20 on the prism 40 side is more likely to be blocked. Therefore, it is possible to suppress the light SL from the outside of the light guide 20 from becoming stray light.

[0040] (Second Embodiment) In the second embodiment, as shown in FIG. 12, the optical member 10 does not include the light shielding layer 60. Otherwise, it is the same as the first embodiment.

[0041] In this second embodiment, as shown in FIG. 13, when the light SL incident from the occupant side of the vehicle 1 travels to and reaches the rough surface 453, a part of the light SL that has reached is reflected by the rough surface 453, and the remaining part is scattered. As a result, since the amount of light SL decreases, the light SL is blocked. Therefore, since the rough surface 453 blocks the light SL instead of the light shielding layer 60, the second embodiment also has the same effect as the first embodiment. Further, in the second embodiment, the following effects are also obtained.

[0042] [2] Since the optical member 10 does not include the light shielding layer 60, the manufacturing of the optical member 10 is shortened by the formation process of the light shielding layer 60. As a result, the manufacturing time of the optical member 10 is shortened and the cost of the optical member 10 is reduced.

[0043] (Third Embodiment) In the third embodiment, the light guide 20 does not have an incident surface 25. Further, as shown in FIGS. 14 and 15, the light guide 20 further has a plurality of incident prisms 70 in addition to the first reflection surface 31, the second reflection surface 32, and the plurality of prisms 40. Further, the optical member 10 further includes an incident light shielding layer 80 in addition to the light guide 20 and the light shielding layer 60. Otherwise, it is the same as the first embodiment. Note that the incident prism 70 corresponds to the first prism, and the prism 40 corresponds to the second prism.

[0044] The incident prism 70 is formed by molding, cutting, blasting, etc. and combinations thereof during the formation of the light guide 20. Further, the incident prism 70 protrudes from the inside of the light guide 20 toward the outside and is formed in a triangular prism shape. Further, the incident prisms 70 are arranged at a predetermined interval. Further, the incident prism 70 includes a prism incident surface 72 and an incident light shielding surface 75.

[0045] The prism incident surface 72 is the surface on which the external scene light Lo is incident. Further, the prism incident surface 72 is parallel to the prism emission surface 42 and intersects the first reflection surface 31 and the second reflection surface 32. Further, the root mean square height of the prism incident surface 72 is, for example, 0.005 μm. Further, the inclination angle of the prism incident surface 72 with respect to the normal direction Dn is the same as the incident surface angle Asi.

[0046] As will be described later, the incident light shielding surface 75 is the surface on which the external scene light Lo is incident, and shields this incident light. Thereby, the incident light shielding surface 75 suppresses the light from being reflected by the incident light shielding surface 75 and being emitted from the prism emission surface 42 to become stray light GLo. Specifically, the incident light shielding surface 75 intersects and is connected to the prism incident surface 72. Further, the incident light shielding surface 75 includes an incident flat surface 751 and an incident rough surface 753.

[0047] Of the plurality of flat surfaces 751 for incidence, one on the second reflection surface 32 side is connected to the second reflection surface 32. The other flat surfaces 751 for incidence are connected to the part inside the light guide 20 of the prism incident surface 72. Further, the root mean square height of the flat surfaces 751 for incidence is, for example, 0.005 μm.

[0048] The rough surface 753 for incidence is connected to the part outside the light guide 20 of the prism incident surface 72 and the flat surfaces 751 for incidence. Also, the root mean square height of the rough surface 753 for incidence is higher than the root mean square heights of the prism incident surface 72 and the flat surfaces 751 for incidence. Therefore, the surface roughness of the rough surface 753 for incidence is greater than the surface roughnesses of the prism incident surface 72 and the flat surfaces 751 for incidence. Further, the root mean square height of the rough surface 753 for incidence is 0.1 μm or more. Also, the ratio of the area of the rough surface 753 for incidence to the area of the light-shielding surface 75 for incidence is 50% or more. In FIG. 15, the ratio of the area of the rough surface 753 for incidence to the area of the light-shielding surface 75 for incidence is set to 50%. Also, where the ratio of the area of the rough surface 753 for incidence to the area of the light-shielding surface 75 for incidence is 50% or more, the ratio of the width of the rough surface 753 for incidence to the width of the light-shielding surface 75 for incidence may be 50% or more.

[0049] The light-shielding layer 80 for incidence is a light absorption film that absorbs 99% or more of light. Also, the light-shielding layer 80 for incidence is formed, for example, by coating, printing, vapor deposition, etc. with a black resin. Further, the light-shielding layer 80 for incidence covers the entire surface of each light-shielding surface 75 for incidence. Also, as will be described later, the light-shielding layer 80 for incidence blocks the light traveling from the dead angle region side toward the prism 70 for incidence. Note that the light-shielding layer 80 for incidence covers the entire surface of the light-shielding surface 75 for incidence, but is not limited thereto, and may cover at least a part of the rough surface 753 for incidence. Also, the light-shielding layer 80 for incidence is formed of a black resin, but is not limited to the black resin, and may be formed of, for example, a metal.

[0050] As described above, the optical member 10 of the third embodiment is configured. Also for this third embodiment, the same effects as those of the first embodiment are achieved. Further, in the third embodiment, the following effects are also achieved.

[0051] [3-1] Here, as shown in FIG. 16, the outside scene light Lo may enter the light-shielding surface 75 for incidence instead of the prism incident surface 72, and the incident light may be reflected by the prism light-shielding surface 45. When the reflected light is emitted from the prism emission surface 42 and travels toward the occupant of the vehicle 1, it becomes stray light GLo.

[0052] Therefore, in the optical member 10 of the third embodiment, the surface roughness of the rough surface 753 for incidence is larger than the surface roughness of the prism incident surface 72. As a result, as shown in FIG. 17, when the outside scene light Lo enters the light-shielding surface 75 for incidence, the incident light is reflected and scattered by the rough surface 753 for incidence. For this reason, the amount of light traveling from the light-shielding surface 75 for incidence toward the prism light-shielding surface 45 decreases. Therefore, it becomes difficult for the light from the light-shielding surface 75 for incidence to reach the prism light-shielding surface 45. Thus, since it becomes difficult for the light from the light-shielding surface 75 for incidence to be reflected by the prism light-shielding surface 45, the light reflected by the prism light-shielding surface 45 becomes difficult to reach the prism emission surface 42. For this reason, since it becomes difficult for the stray light GLo to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot region is improved.

[0053] [3-2] The light-shielding surface 75 for incidence includes a flat surface 751 for incidence and a rough surface 753 for incidence. Further, the ratio of the area of the rough surface 753 for incidence to the area of the light-shielding surface 75 for incidence is 50% or more. Thus, since the area of the rough surface 753 for incidence included in the light-shielding surface 75 for incidence is equal to or greater than the area of the flat surface 751 for incidence, the probability that the external light Lo is reflected by the rough surface 753 for incidence increases. For this reason, the external light Lo incident on the light-shielding surface 75 for incidence is likely to be reflected and scattered. For this reason, the amount of light traveling from the light-shielding surface 75 for incidence toward the prism light-shielding surface 45 is likely to decrease. Therefore, it becomes difficult for the light from the light-shielding surface 75 for incidence to reach the prism light-shielding surface 45. Thus, since it becomes difficult for the light from the light-shielding surface 75 for incidence to be reflected by the prism light-shielding surface 45, the light reflected by the prism light-shielding surface 45 is less likely to reach the prism light-emitting surface 42. For this reason, since the stray light GLo is less likely to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0054] [3-3] The root mean square height of the rough surface 753 for incidence is 0.1 μm or more. Thus, the external light Lo incident on the light-shielding surface 75 for incidence is likely to be reflected and scattered. For this reason, the amount of light traveling from the light-shielding surface 75 for incidence toward the prism light-shielding surface 45 is likely to decrease. Therefore, it becomes difficult for the light from the light-shielding surface 75 for incidence to reach the prism light-shielding surface 45. Thus, since it becomes difficult for the light from the light-shielding surface 75 for incidence to be reflected by the prism light-shielding surface 45, the light reflected by the prism light-shielding surface 45 is less likely to reach the prism light-emitting surface 42. For this reason, since the stray light GLo is less likely to reach the occupant of the vehicle 1, the visibility of the scenery in the blind spot area is improved.

[0055] [3-4] The optical member 10 further includes an incidence light-shielding layer 80 corresponding to the light-shielding portion. The incidence light-shielding layer 80 covers the rough surface 753 for incidence and blocks the light from outside the light guide 20. Thus, since the light from outside the light guide 20 on the blind spot area side is blocked, it is suppressed that the external light Lo becomes the stray light GLo.

[0056] [3-5] The light-shielding layer 80 for incidence is a light-absorbing film that absorbs light. As a result, the external scene light Lo traveling toward the light-shielding surface 75 for incidence is absorbed. Therefore, the external scene light Lo traveling toward the light-shielding surface 75 for incidence is more likely to be blocked. Accordingly, it is possible to suppress the external scene light Lo from becoming stray light GLo.

[0057] (Other Embodiments) The present disclosure is not limited to the above-described embodiments, and appropriate modifications can be made to the above-described embodiments. Also, in each of the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is explicitly stated that they are essential or where they are considered to be clearly essential in principle.

[0058] In each of the above-described embodiments, the root mean square height is cited as the surface roughness. In contrast, the surface roughness is not limited to the root mean square height, and may be the maximum peak height, the maximum valley depth, the maximum height, the arithmetic mean height, or the like. Note that the maximum peak height, the maximum valley depth, the maximum height, the arithmetic mean height, or the like is measured by a measurement method conforming to, for example, ISO25178 and JIS B0601.

[0059] In the third embodiment above, the prism light-shielding surface 45 in the prism 40 of the light guide 20 includes the rough surface 453, and the light-shielding surface 75 for incidence in the incidence prism 70 of the light guide 20 includes the rough surface 753 for incidence. In contrast, since the light-shielding surface 75 for incidence includes the rough surface 753 for incidence, the prism light-shielding surface 45 may not include the rough surface 453.

[0060] In the third embodiment above, the optical member 10 includes the light-shielding layer 80 for incidence. In contrast, the optical member 10 may not include the light-shielding layer 80 for incidence. In this case, similar to the second embodiment, the rough surface 753 for incidence blocks the external scene light Lo instead of the light-shielding layer 80 for incidence. Also, since the optical member 10 does not include the light-shielding layer 80 for incidence, the manufacturing of the optical member 10 is shortened by the formation process of the light-shielding layer 80 for incidence. As a result, the manufacturing time of the optical member 10 is shortened and the cost of the optical member 10 is reduced.

[0061] In each of the above embodiments, the prism 40 and the incident prism 70 are triangular prism-shaped, but are not limited to being triangular prism-shaped. For example, they may be trapezoidal prism-shaped.

[0062] In each of the above embodiments, the light-shielding layer 60 and the incident light-shielding layer 80 are formed of a light absorption film, but are not limited to being formed of a light absorption film, and may be formed of a light diffusing material, a retroreflective material, or the like.

[0063] In each of the above embodiments, the second reflecting surface 32 is parallel to the first reflecting surface 31. In contrast, the second reflecting surface 32 is not limited to being parallel to the first reflecting surface 31, and may be in a form that is not parallel to the first reflecting surface 31 according to the distance from the optical member 10 to the viewer.

Explanation of Reference Numerals

[0064] 10 Optical member 20 Light guide 25, 75 Incident surface 31 First reflecting surface 32 Second reflecting surface 40, 70 Prism 42 Emitting surface 45, 75 Light-shielding surface 453, 753 Rough surface 60, 80 Light-shielding layer

Claims

1. a first prism (70) including an entrance surface (72) on which external light (Lo) from a blind spot area is incident and a light-shielding surface (75) connected to the entrance surface and on which the external light is incident; a first reflecting surface (31) that reflects light from the entrance surface; a second reflecting surface (32) that reflects light reflected by the first reflecting surface; an exit surface (42) that emits light from the entrance surface and light reflected by the second reflecting surface to the outside; and a second prism (40) that is connected to the exit surface and includes a surface (45) on which light from the light-shielding surface is incident; The light blocking surface includes a rough surface (753); The rough surface has a larger surface roughness than the incident surface.

2. The light-shielding surface has a flat surface (451) connected to the rough surface and having a surface roughness smaller than that of the rough surface, 2. The optical member according to claim 1, wherein a ratio of an area of ​​the rough surface to an area of ​​the light-shielding surface is 50% or more.

3. 3. The optical member according to claim 1, wherein the root mean square height of the roughened surface is 0.1 [mu]m or more.

4. 4. The optical member according to claim 1, further comprising a light shielding portion (60, 80) that covers the rough surface and blocks light from outside the light guide body.

5. The optical member according to claim 4 , wherein the light blocking portion is a light absorbing film that absorbs light.

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