Optical member

Abstract

To provide an optical member that comprises an emission part having a plurality of projection-shaped prism parts and can suppress a decrease in visibility of an outward scene due to incidence of light on a different surface from an emission surface of a prism part.SOLUTION: An optical member 1 consists of a light guide body 2 comprising an incidence surface 2a, an emission part 2b adjoining the incidence surface 2a, and a smooth surface 2c opposed to the emission part 2b. The emission part 2b consists of a plurality of projection-shaped prism parts 3 and a plurality of flat parts 5 as flat surfaces. A prism part 3 has an emission surface 3a emitting incident light from the incidence surface 2a as one surface, and the other surface 3b adjoining the one surface, and also has a cut part 4 formed on the other surface 3b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an optical member that internally reflects a portion of light incident from an incident surface and emits the incident light and its reflected light to the outside from a surface different from the incident surface. [Background technology]

[0002] Conventionally, this type of optical member is, for example, attached to a light shielding body, and is a blind spot auxiliary device that allows the outside light from the blind spot area generated by the light shielding body to enter the inside, reflects it inside, and emits the outside light from a surface different from the incident surface of the outside light, thereby making the blind spot area visible. An example of such an optical member is described in Patent Document 1. The optical member described in Patent Document 1 is composed of a translucent light guide, and a part of the outside light incident from the incident surface of the light guide is guided inside by total reflection and is emitted to the outside from an emission part different from the incident surface, allowing a user on the emission part side to view the outside view in the blind spot. This results in a half-mirrorless structure that does not require a half mirror made of a reflective material different from the light guide on the emission part side, and reduces loss due to absorption of outside light in the light guide inside the light guide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-028532 A Summary of the Invention [Problem to be solved by the invention]

[0004] The optical member described in Patent Document 1 has an exit portion composed of a plurality of protruding prism portions and a flat portion, one surface of the prism portion is an exit surface parallel to the entrance surface, and the other surface adjacent to the exit surface is covered with a light-shielding film. This optical member is configured such that the light of the outside scene incident from the entrance surface that reaches the exit surface becomes exit light that is emitted to the outside, and the user is able to visually recognize the scene in the blind spot area by the exit light.

[0005] However, as a result of thorough investigation by the inventors into the above-mentioned optical components, it was newly discovered that, of the external light incident from the entrance surface, light that enters the other surface of the prism portion may undergo interfacial reflection and be superimposed on the exiting light, thereby reducing the visibility of the blind spot area.

[0006] In view of the above, the present disclosure aims to provide an optical element that has an emission portion composed of a plurality of protruding prism portions and a flat portion, and that is capable of suppressing a decrease in visibility of the outside scene caused by light being incident on a surface of the prism portion other than the emission surface. [Means for solving the problem]

[0007] An optical element according to one aspect of the present disclosure is an optical element that guides external scene light (L1) by internally reflecting it, and has an incident surface (2a) into which the external scene light is incident, a plurality of protruding prism portions (3) and a plurality of flat portions (4) that are flat surfaces, and has an exit portion (2b) extending in a direction intersecting the incident surface, a smooth surface (2c) facing the exit portion, and an end surface (2e) located on the opposite side of the incident surface and connecting the exit portion and the smooth surface, and is provided with a plurality of light guides (2) made of a light-transmitting material, and the exit portion is formed by repeatedly arranging a plurality of prism portions and flat portions along a direction from the incident surface side toward the end surface side, and the external scene light incident from the incident surface is incident light (L2), and the plurality of prism portions have an exit surface (3a) that emits a portion of the incident light to the outside and another surface (3b) adjacent to the exit surface, and at least a portion of the plurality of prism portions has a cutout portion (4) formed on the other surface.

[0008] This optical member includes an incident surface, an exit portion made up of a plurality of prism portions and a flat portion, and a light guide having a smooth surface facing the exit portion, and the prism portion has an exit surface from which a portion of the light incident from the incident surface is exited, and another surface adjacent to the exit surface. At least some of the plurality of prism portions have a notch portion formed on the other surface. As a result, even if a portion of the outside light incident from the incident surface is incident on the other surface and is reflected at an interface, the light reflected at the interface is blocked by the notch portion, so that the light reflected at the interface is prevented from reaching the incident surface and being superimposed on the exit light. Therefore, even if the incident light is reflected at the other surface of the prism portion, the optical member can suppress the decrease in visibility of the outside view.

[0009] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an optical member according to a first embodiment. [Diagram 2] 2 is an explanatory diagram of light guide in the optical member of FIG. 1. [Diagram 3] 6A and 6B are explanatory diagrams of interface reflection at a prism portion of an optical member of a comparative example. [Figure 4] 11 is a graph showing the relationship between the angle of incidence of light to an interface and the interface reflectance in an optical member of a comparative example. [Diagram 5] 2 is an enlarged view of region V in FIG. 1 and is an explanatory diagram of suppression of interfacial reflection in a prism portion of the optical member according to the first embodiment. FIG. [Figure 6] 5A and 5B are explanatory diagrams of a notch portion in a prism portion. [Figure 7] 5 is a cross-sectional view showing a modified example of the optical member of the first embodiment. FIG. [Figure 8] 5A and 5B are explanatory diagrams of a prism portion in which a notch is formed. [Figure 9] 11A and 11B are explanatory diagrams for explaining the design of a prism portion in which a notch is formed. [Figure 10] FIG. 6 is a cross-sectional view showing an optical member according to a second embodiment. [Figure 11] 11 corresponds to an enlarged cross-sectional view of region XI in FIG. 10, and is an explanatory diagram of the effects of the cutout portion of the prism portion and the light-shielding film. FIG. [Figure 12] FIG. 12 is a view corresponding to FIG. 11 and is an enlarged cross-sectional view showing an optical member according to a third embodiment. [Figure 13] FIG. 12 is a view corresponding to FIG. 11 and shows an enlarged cross-sectional view of an optical member according to another embodiment. [Figure 14] FIG. 11 is a cross-sectional view showing an optical member according to another embodiment. [Figure 15] FIG. 11 is a cross-sectional view showing an optical member according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0012] (First embodiment) An optical member 1 according to a first embodiment will be described with reference to the drawings.

[0013] [Basic configuration] The optical member 1 of the present embodiment can be used as a blind spot assistance device that is attached to, for example, a member or obstacle that blocks a user's field of vision and creates a blind spot, allowing the user to visually recognize the view in the blind spot area.

[0014] As shown in FIG. 1, an optical member 1 of this embodiment is made up of a light guide 2 having an entrance surface 2a, an exit portion 2b, a smooth surface 2c, an inclined surface 2d, and a terminal surface 2e.

[0015] For convenience of explanation, as shown in FIG. 1, the direction along the normal direction to the flat portion 5 or the smooth surface 2c of the optical member 1, which will be described later, and connecting the opposing exit portion 2b and smooth surface 2c, will be referred to as the "thickness direction D1". Also, the direction perpendicular to the thickness direction D1, which is the direction from the incident surface 2a toward the terminal surface 2e, that is, the direction in which the light incident from the incident surface 2a is guided, will be referred to as the "light guide direction D2". The light guide direction D2 is the direction along which the multiple prism portions 3 and flat portions 5, which will be described later, are repeatedly arranged, and is perpendicular to the extension direction of the prism portions 3 and flat portions 5, and may also be referred to as the arrangement direction.

[0016] 2, the optical member 1 is configured such that a part of the light incident from the incident surface 2a of the light guide 2 into the inside is reflected by the emission portion 2b, and the light reflected by the emission portion 2b is reflected by the smooth surface 2c and directed again toward the emission portion 2b side. For example, the optical member 1 guides external light from the incident surface 2a inside the light guide 2 and emits it to the outside from the emission portion 2b, thereby allowing a user on the emission portion 2b side to view the outside view in the blind spot area created by the light shielding body 100. Note that, for example, in the case of in-vehicle use, the light shielding body 100 is configured to generate a blind spot area such as an A-pillar of a car, but is not limited thereto and can be appropriately changed.

[0017] For ease of explanation, as shown in Figure 2, external light incident on the incident surface 2a will be referred to as "external light L1," light entering the inside of the light guide 2 from the incident surface 2a will be referred to as "incident light L2," and light emitted from the inside of the light guide 2 to the outside will be referred to as "emitted light L3."

[0018] The light guide 2 is a single, substantially plate-shaped member made of a light-transmitting material such as a resin material, for example, polyethylene terephthalate, polycarbonate, polyethylene, or acrylic, or glass. The light guide 2 is formed, for example, by a known resin molding method using a mold or the like (not shown). The light guide 2 is configured such that a part of the incident light L2 from the incident surface 2a enters the prism portion 3 of the exit portion 2b, and the remaining part of the incident light L2 is reflected by the flat portion 5, and this reflected light is directed toward the smooth surface 2c. The light guide 2 is designed such that the incident light L2 reflected by the flat portion 5 is totally reflected by the smooth surface 2c and the flat portion 5, and guided inside. Specifically, the light guide 2 is designed to satisfy the following formula (1) when the refractive index of the constituent material is n, the incident angle of the incident light L2 with respect to the smooth surface 2c and the flat portion 5, i.e., the light guide angle, is φ, and the external medium of the light guide 2 is an air layer with a refractive index of 1. The light guide angle φ is the angle between the direction in which the incident light L2 incident on the flat portion 5 or the smooth surface 2c travels and the thickness direction D1.

[0019] sinφ>1 / n (1) As a result, even though the light guide 2 does not have a half mirror or mirror made of a reflective material different from the light guide 2, a portion of the incident light L2 is repeatedly reflected between the flat portion 5 and the smooth surface 2c, and the incident light L2 is emitted to the outside from the exit surface 3a of the prism portion 3, which will be described later.

[0020] The incident surface 2a is a surface that allows the external light L1 to enter the inside. The incident surface 2a is adjacent to the exit portion 2b and extends in a direction intersecting the exit portion 2b and the smooth surface 2c. For example, the incident surface 2a is inclined so as to approach the terminal surface 2e as it approaches the smooth surface 2c side, and is a flat surface inclined at an inclination angle ψ, which is an angle with the thickness direction D1. The inclination angle ψ of the incident surface 2a is smaller than the light guide angle φ. At this time, if the angle of the external light L1 with respect to the thickness direction D1 is θ, and ψ<π / 2-φ according to the refraction condition, the incident light L2 is refracted in a direction in which the light guide angle φ is larger than the angle θ of the external light L1, and is guided to a wider range of the exit portion 2b. The angle θ can also be said to be the incident angle of the external light L1 with respect to the light guide body 2. In the light guide 2, for example, φ is the total reflection angle, and since the refractive index of a typical light-transmitting resin material is 1.4 or more, n·sinφ>1 gives φ>45.3, so that the light guide 2 has a structure that satisfies φ>ψ.

[0021] The emission portion 2b is formed at a position adjacent to and intersecting with the incident surface 2a, and includes, for example, a plurality of prism portions 3, which are triangular protrusions in a cross-sectional view, and a plurality of flat portions 5. The emission portion 2b includes, for example, the prism portions 3 and the flat portions 5 arranged alternately and repeatedly from the incident surface 2a toward the terminal surface 2e.

[0022] The multiple prism parts 3 are protrusions protruding from the flat part 5, and are arranged, for example, in parallel, and in this embodiment, the height in the thickness direction D1 and the width in the light guide direction D2 are approximately the same. In this specification, "approximately the same" includes the case where they are completely the same, as well as the case where they are almost the same with a slight difference due to unavoidable factors such as processing errors. For example, the multiple prism parts 3 have an exit surface 3a that is parallel to the incident surface 2a in a cross-sectional view and emits a part of the incident light L2 to the outside, and another surface 3b adjacent to the exit surface 3a. For example, the exit surface 3a of the multiple prism parts 3 is parallel to the incident surface 2a, that is, the inclination angle with respect to the thickness direction D1 is ψ. As a result, the incident light L2 that reaches the exit surface 3a is emitted to the outside as the exit light L3 at the same angle θ as the outside scene light L1. This ensures continuity between an outside view not passing through the optical member 1 and an outside view in a blind spot area that is made visible by the optical member 1, as viewed from a user positioned on the emission portion 2b side. The multiple prism portions 3 have, for example, a constant pitch interval between adjacent prism portions 3 in the light guiding direction D2.

[0023] The plurality of prism portions 3 have cutout portions 4 formed on the other surface 3b. The cutout portions 4 are, for example, triangular grooves in a cross-sectional view. The cutout portions 4 are provided to prevent the light L2 that is incident on the other surface 3b and is interfacially reflected by the other surface 3b from entering the exit surface 3a. This will be described in detail later.

[0024] The flat portions 5 are, for example, flat surfaces that face the smooth surface 2c and are arranged parallel to it. The flat portions 5 are, for example, arranged on the same plane and form one plane. The flat portions 5 function as a reflecting surface that reflects the incident light L2 toward the smooth surface 2c by total reflection because the incident light L2 from the incident surface 2a is incident at an angle equal to or greater than the critical angle. The flat portions 5 are, for example, approximately parallel to the smooth surface 2c. In this specification, "approximately parallel" includes not only the case of being completely parallel, but also the case of being almost parallel with a slight unavoidable difference due to processing errors and the like.

[0025] The inclined surface 2d is a surface connecting the incident surface 2a and the smooth surface 2c, and is inclined so that, for example, the closer it is to the smooth surface 2c, the closer it is to the terminal surface 2e, and is a surface that protrudes from the smooth surface 2c. In other words, the incident surface 2a and the inclined surface 2d form one large protruding prism portion in a cross-sectional view. That is, the light guide 2 is configured such that the height in the thickness direction D1 of one prism portion formed by the incident surface 2a and the inclined surface 2d is greater than the height T from the flat portion 5 of the exit portion 2b to the smooth surface 2c. This allows the light guide 2 to widen the area of ​​the exit portion 2b where the incident light L2 from the incident surface 2a first arrives.

[0026] The end surface 2e is a surface that connects the emission portion 2b and the smooth surface 2c. The end surface 2e is, for example, a single flat surface. The inclination of the end surface 2e is arbitrary, but for example, the end surface 2e may be configured to form a single flat surface together with the emission surface 3a of the prism portion 3 that is the closest to the end surface 2e in the emission portion 2b, and function as the last emission surface in the light guiding direction D2.

[0027] In addition, the side surfaces of the light guide 2, which are located at both ends in a direction perpendicular to the plane formed by the thickness direction D1 and the light guide direction D2 and connect the entrance surface 2a, the exit surface 2b, the smooth surface 2c, the inclined surface 2d and the terminal surface 2e, are surfaces that do not contribute optically, and their shapes, configurations, etc. are arbitrary.

[0028] The basic configuration of the optical member 1 has been described above.

[0029] [Cutout part] Next, the effect of the notch 4 formed in the prism portion 3 will be described in comparison with an optical member of a comparative example shown in FIG.

[0030] 3 and 5, for convenience of explanation, of the incident light L2, the light that directly enters the exit surface 3a of the prism section 3 is referred to as the "first incident light L2a," and the light that enters the other surface 3b is referred to as the "second incident light L2b." In addition, the first incident light L2a that is emitted to the outside from the exit surface 3a or the exit surface 10a is referred to as the "normally emitted light L3a," and the light of the second incident light L2b that is reflected by the other surface 3b or the adjacent surface 10b is referred to as the "stray light L3b."

[0031] 3, the optical member of the comparative example is formed by repeatedly and alternately arranging prism portions 10, each having a protruding shape with no notch portion 4, and flat portions 5. Prism portion 10 has exit surface 10a that emits incident light L2 to the outside, and adjacent surface 10b, which is a flat surface adjacent to exit surface 10a. In addition, adjacent surface 10b of prism portion 10 is covered with light-shielding film 11 that absorbs visible light.

[0032] In the optical member of the comparative example, the second incident light L2b undergoes interfacial reflection depending on the incident angle with respect to the adjacent surface 10b, and the reflected light reaches the exit surface 10a. Specifically, for example, when the refractive index of the light guide is 1.49, the refractive index of the light blocking film 11 is 1.59, and the refractive index difference at the interface with the adjacent surface 10b is 0.1, it was found that the interfacial reflectance at the adjacent surface 10b increases according to the incident angle ξ with respect to the adjacent surface 10b, as shown in FIG.

[0033] The incidence angle ξ here is the angle between the direction in which the second incident light L2b travels and the normal direction to the adjacent surface 10b, as shown in Fig. 3. The interface reflectance is the rate at which the second incident light L2b causes interface reflection, i.e., Fresnel reflection, on the adjacent surface 10b.

[0034] In the case of the optical member of the comparative example, according to an optical simulation, the interface reflectance increases gradually when the incident angle ξ exceeds 60°, and then increases sharply when ξ exceeds 80°, reaching approximately 40% when ξ = 86°. When the interface reflectance increases in this way, the proportion of stray light L3b that is reflected by the adjacent surface 10b and reaches the exit surface 10a, i.e., the proportion of stray light L3b that is superimposed on the regular exit light L3a, increases, and the visibility of the blind spot area decreases.

[0035] In contrast, in the optical member 1 of this embodiment, as shown in FIG. 5, a cutout portion 4 is formed on the other surface 3b of the prism portion 3, and the parallel surface 4a of the cutout portion 4 prevents the stray light L3b from traveling. The parallel surface 4a is, for example, approximately parallel to the flat portion 5. The cutout portion 4 has, for example, an orthogonal surface 4b perpendicular to the parallel surface 4a, and is a wedge-shaped groove in cross section. The cutout portion 4 is formed in the prism portion 3, so that even if the second incident light L2b is reflected at the other surface 3b, the stray light L3b enters the parallel surface 4a, and further undergoes interfacial reflection at the parallel surface 4a, so that the stray light L3b travels in a direction different from the exit surface 3a. Even if the stray light L3b reaches the exit surface 3a, it is emitted at an angle completely different from the regular emission light L3a, so that the overlapping of the regular emission light L3a and the stray light L3b is suppressed, and visibility of the blind spot area can be ensured.

[0036] For example, as shown in Fig. 6, when the width L4 of the other surface 3b of the prism portion 3 along the light guide direction D2 is 0.6 mm, the notch portion 4 is formed at a position where the distance L5 from the tip of the other surface 3b is 0.16 mm. In this case, the width of the parallel surface 4a along the light guide direction D2 of the notch portion 4 is 0.1 mm, and the width of the perpendicular surface 4b in the thickness direction D1 is 0.05 mm. The position and dimensions of the notch portion 4 are, for example, as described above, but are not limited thereto, and it is sufficient that the parallel surface 4a has a dimension that does not impede the travel of the first incident light L2a, and the formation position and dimensions on the other surface 3b can be appropriately changed.

[0037] For example, the end of the other surface 3b on the light guide 2 side is defined as the root portion 3ba, and the position of the emission surface 3a where the first incident light L2a with a light guide angle φ passing through the root portion 3ba reaches is defined as the arrival point 3aa. In this case, the cutout portion 4 may have a dimension such that the parallel surface 4a does not overlap with a virtual line connecting the arrival point 3aa and the root portion 3ba. Also, as shown in FIG. 6, the cutout portion 4 is designed to satisfy, for example, 5°≦α<180°, where α is the angle between the other surface 3b and the parallel surface 4a. In other words, the parallel surface 4a may have a shape or inclination that can prevent the stray light L3b from reaching the emission surface 3a, and may not be substantially parallel to the flat portion 5, or may not be parallel to the other surface 3b.

[0038] According to this embodiment, even if the second incident light L2b undergoes interfacial reflection on the other surface 3b of the prism portion 3, the cutout portion 4 reflects the stray light L3b in a direction different from the exit surface 3a of the optical member 1. Therefore, the optical member 1 is one in which a decrease in visibility of the blind spot caused by interfacial reflection on the other surface 3b of the prism portion 3 is suppressed.

[0039] (Modification of the first embodiment) 7, the optical member 1 may have a configuration in which the emission portion 2b has a prism portion 3 having a notch portion 4, and a prism portion 6 that does not have a notch portion 4. Specifically, the optical member 1 may have a configuration in which the emission portion 2b has a first region 2ba composed of a plurality of flat portions 5 and a prism portion 6, and a second region 2bb composed of the plurality of flat portions 5 and a prism portion 3.

[0040] Prism portion 6 is a protrusion similar to prism portion 3, and includes exit surface 6a that is substantially parallel to entrance surface 2a, and adjacent surface 6b that is a flat surface adjacent to exit surface 6a. Prism portion 6 is formed at a position where stray light L3b of exit portion 2b does not reach the viewpoint of a user located on the side of exit portion 2b, even if it is emitted.

[0041] Specifically, as shown in FIG. 8, for example, the position of the user's eye on the side of the emission unit 2b is taken as the viewpoint Pe, and the midpoint between the tip and the base of the emission surface of the prism unit is taken as the midpoint, and virtual straight lines VL1 to VLn connecting the viewpoint Pe and the midpoint of the prism unit are considered. The number of prism units is n (n: an integer of 1 or more), and the kth prism unit (k: an integer of 1 or more and n or less) is taken as the number of the n prism units counted from the entrance surface 2a side. The virtual straight line VLk connects the midpoint of the kth prism unit and the viewpoint Pe. Also, the angle between the virtual straight line VLk and the thickness direction D1 is taken as Xk. Also, as shown in FIG. 9, for example, the light guide angle of the first incident light L2a that reaches the emission surface of the kth prism unit is taken as φk, and the emission angle of the light L3 of the first incident light L2a with the light guide angle φk emitted to the outside from the emission surface is taken as θk. The inclination angle of the exit surface with respect to the thickness direction D1 is ω, and the inclination angle of the other surface or adjacent surface with respect to the thickness direction D1 is δ. In this case, the notch portion 4 is formed in the prism portion that satisfies the following formula (2).

[0042] δ<φk=sin -1 {1 / n×sin(90-Xk-ω)}···(2) In a prism portion that satisfies formula (2), the stray light L3b is superimposed on the regular emission light L3a, and the stray light L3b reaches the viewpoint Pe. In other words, in a prism portion that does not satisfy formula (2), even if the stray light L3b is emitted from the exit surface, the stray light L3b does not reach the viewpoint Pe, and the stray light L3b is not recognized as a ghost image by the user.

[0043] This modification also provides the optical member 1 that can obtain the same effects as those of the first embodiment. The optical member 1 of this modification is suitable for use in an application in which the positional relationship between the optical member 1 and the user's viewpoint Pe falls within a predetermined range, for example, when the light blocking body 100 is an A-pillar of a vehicle and the user is the driver of the vehicle.

[0044] Second embodiment The optical member 1 of the second embodiment will be described with reference to FIGS.

[0045] 10, the optical member 1 of this embodiment differs from the first embodiment in that it further includes a light-shielding film 7 that covers part of the other surface 3b of the prism portion 3. In this embodiment, this difference will be mainly described.

[0046] The light-shielding film 7 covers the notch 4 and the area from the notch 4 to the tip of the other surface 3b, as shown in FIG. 11, for example. Hereinafter, for convenience of explanation, the notch 4 and the area from the notch 4 to the tip of the other surface 3b are referred to as the "tip side area". The light-shielding film 7 is made of any light-absorbing material that absorbs visible light, such as black paint, and is formed by any film-forming method, such as spray coating. The light-shielding film 7 is provided to prevent external light GL from the exit portion 2b side from entering the tip side area and being emitted from the exit surface 3a, which may cause a ghost image. The light-shielding film 7 is, for example, 0.6 times or more the length of the other surface 3b, and is formed to cover at least the notch 4, but is not limited thereto. For example, the light-shielding film 7 may cover at least the notch 4 in the tip side area, and may not cover the entire tip side area.

[0047] The optical member 1 of this embodiment also provides the same effects as those of the first embodiment. In addition, by providing the light-shielding film 7 covering the cutout portion 4 of the prism portion 3, the occurrence of ghost images caused by external light GL is suppressed, and the effect of further improving the visibility of blind spots is also obtained. In addition, the optical member 1 can be manufactured more easily than when the light-shielding film 7 is formed over the entire other surface 3b.

[0048] Third embodiment The optical member 1 of the third embodiment will be described with reference to FIG.

[0049] 12, the optical member 1 of this embodiment differs from the above-described first embodiment in that a plurality of cutout portions 4 are formed on the other surface 3b of the prism portion 3, and a light-shielding film 7 is provided to cover the cutout portions 4. In this embodiment, this difference will be mainly described.

[0050] In this embodiment, a plurality of cutouts 4 are formed on the other surface 3b in a state separated from each other. For example, the size of the cutouts 4 is made smaller as the number of the cutouts 4 increases, so that the first incident light L2a is less likely to be blocked, and the amount of the first incident light L2a can be secured. The number of the cutouts 4 can be changed as appropriate.

[0051] In this embodiment, the light-shielding film 7 is formed so as to fill the grooves formed by the individual cutouts 4, and covers only the cutouts 4. The light-shielding film 7 is formed so as to cover only the cutouts 4, for example, by dropping paint made of a light-absorbing material onto the end of the cutouts 4 and spreading it to form a film, or by forming a film over the entire area of ​​the other surface 3b and then removing the parts other than the cutouts 4. The light-shielding film 7 covers only the multiple cutouts 4 that are smaller in size than in the first embodiment, so the proportion of the light-shielding film 7 on the other surface 3b is reduced. Therefore, when viewed from the emission portion 2b side, the light-shielding film 7 is less noticeable, improving the design of the emission surface 3a, and suppressing a decrease in visibility of the outside view caused by the light-shielding film 7, which is caused by the user's eyes being less likely to focus on the light-shielding film 7.

[0052] The present embodiment also provides the optical member 1 with the same effects as those of the first and second embodiments. In addition, by providing a plurality of cutout portions 4 smaller than those of the first embodiment and forming the light-shielding film 7 to cover only the cutout portions 4, the area of ​​the light-shielding film 7 is reduced, which prevents the user's eyes from focusing on the light-shielding film 7, and provides the effect of further improving visibility of the outside scene.

[0053] (Other embodiments) (1) Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element thereof, more than one, or less than one, are also within the scope and concept of the present disclosure.

[0054] For example, the optical member 1 of the third embodiment may not have the light-shielding film 7. In this way, the optical member 1 may have a configuration in which the above-mentioned embodiments and their modified examples, as well as other embodiments described below, are freely combined or nonessential components are excluded, except in cases where they are clearly incompatible.

[0055] (2) In the optical member 1, the cutout portion 4 may be a curved groove having only one curved surface 4c, as shown in Fig. 13. In this case, the machining precision required for the cutout portion 4 to have a shape having parallel surfaces 4a and orthogonal surfaces 4b, i.e., a so-called pin-angle shape, is not required, and the machining precision of the cutout portion 4 is relaxed, making the optical member 1 easier to manufacture.

[0056] (3) As shown in FIG. 14, for example, the optical member 1 may have an emission section 2b that is composed of a plurality of regions in which the ratio of the width of the prism section 3 to the width of the flat section 5 in the light guide direction D2 is different. For example, the emission section 2b may be composed of three regions: a first region 2b1 in which the ratio of the width of the flat section 5 is about 66%, a second region 2b2 in which the ratio of the width of the flat section 5 is about 50%, and a third region 2bc composed only of the prism section 3. In this case, the ratio of the flat section 5 is the reflectance of the incident light L2 in each region of the emission section 2b, and the remainder is the emission rate. Then, the emission rates of the first region 2b1, the second region 2b2, and the third region 2b3 are approximately the same at about 33%, and the brightness unevenness of the scene viewed through the emission section 2b is suppressed. The number of regions constituting the emission section 2b is arbitrary, and the ratio of the width of the flat section 5 in each region is appropriately designed so that the emission rates are approximately the same depending on the number of regions.

[0057] (4) For example, as shown in FIG. 15, the optical member 1 may have no inclined surface 2d, and the entrance surface 2a and the smooth surface 2c may be adjacent to each other.

[0058] (5) It goes without saying that in each of the above embodiments, the elements constituting the embodiment are not necessarily essential, except when expressly stated as essential or when it is clearly considered essential in principle. In addition, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when expressly stated as essential or when it is clearly limited to a specific number in principle. In addition, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., except when expressly stated as essential or when it is clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0059] 2...Light guide, 2a...Incidence surface, 2b...Emission part, 2c...Smooth surface, 2e...Terminal surface 3: prism portion, 3a: exit surface, 3b: other surface, 4: notch portion, 4a: parallel surface 4c...curved surface, 7...light-shielding film, L1...external light, L2...incident light, Pe...user's viewpoint

Claims

1. An optical member that internally reflects and guides external light (L1), The light guide includes a plurality of light guide bodies (2) made of a light-transmitting material, the light guide body (2) having an entrance surface (2a) on which the external light is incident, a plurality of protruding prism portions (3) and a plurality of flat portions (4) which are flat surfaces, an exit portion (2b) extending in a direction intersecting the entrance surface, a smooth surface (2c) facing the exit portion, and a terminal surface (2e) located on the opposite side of the entrance surface and connecting the exit portion and the smooth surface, the emission portion is configured such that a plurality of the prism portions and the flat portion are repeatedly arranged along a direction from the entrance surface side toward the terminal surface side, The outside scene light incident from the entrance surface is regarded as incident light (L2), and the plurality of prism portions have an exit surface (3a) that emits a part of the incident light to the outside and another surface (3b) adjacent to the exit surface, At least some of the prism portions have a notch (4) formed on the other surface.

2. 2. The optical member according to claim 1, wherein the prism portion having the cutout portion among the plurality of prism portions has the cutout portion and a part of the area of ​​the other surface from the cutout portion to the tip covered by a light-shielding film (7).

3. The optical member according to claim 1 , wherein the prism portion having the cutout portion among the plurality of prism portions has a plurality of the cutout portions formed therein.

4. 4. The optical member according to claim 3, wherein at least the cutouts on the other surface of the prism portion in which the plurality of cutouts are formed are covered with a light-shielding film (7).

5. The position of the user's eyes on the side of the emission unit is defined as a viewpoint (Pe), A point located halfway between the root and the tip of the exit surface is defined as a midpoint, and an angle formed between a virtual line (VL1 to VLk) connecting the midpoint of a k-th prism portion (k: an integer of 1 or more) from the entrance surface side among the plurality of prism portions and the viewpoint and a normal direction (D1) to the flat portion is defined as Xk, The angle between the other surface and the normal direction is δ, The angle between the emission surface and the normal direction is ω, The angle between the incident light (L2a) reaching the exit surface of the kth prism portion and the normal direction is φk, The refractive index of the light guide is n, The cutout portion is a portion of the plurality of prism portions, in which δ<φk=sin －1 2. The optical member according to claim 1, wherein the prism portion is formed to satisfy the formula {1 / n×sin(90−Xk−ω)}.

6. 6. The optical member according to claim 1, wherein the cutout portion has a parallel surface (4a) parallel to the flat portion.

7. 6. The optical member according to claim 1, wherein the cutout portion is curved and has only one curved surface.

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