Optical member

Abstract

To reduce, in an optical member in which an emission part of incidence light is provided with a pattern structure having a plurality of prism parts and flat parts, uncomfortable feeling, caused by the pattern structure, of a scene which is made to be visually recognized through the emission part.SOLUTION: A light guiding body formed of a light transmissive material is formed such that an emission part has a plurality of projection-like prism parts 3 and a plurality of flat parts 4 being flat surfaces. In the emission part, at least one luminance difference reducing part 5 is formed between adjacent two prism parts 3. A portion of incidence light having been incident on an inside of the light guiding body is emitted from the prism parts 3 to an outside, an other portion thereof is reflected by the flat parts 4 by total reflection in the inside of the light guiding body, and an other portion thereof is emitted from the luminance difference reducing part 5 to the outside.SELECTED DRAWING: Figure 3

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 above-mentioned optical member has an emission portion in which prism portions, which are triangular protrusions when viewed in cross section, and flat portions, which are flat surfaces, are arranged alternately, and a portion of the light incident on the light guide is totally reflected by the flat surface, and another portion of the light is emitted to the outside from the emission surface of the prism portion.

[0005] As a result of intensive research by the inventors into this optical member, they have newly discovered that when the emission section has a configuration including a plurality of prism sections and a flat section, the emission section is divided into sections that emit light to the outside and sections that do not, resulting in a brightness difference and possibly causing the viewer to feel uncomfortable.

[0006] In view of the above, the present disclosure aims to provide an optical member that has a configuration in which the emission section has a portion that emits light to the outside and a portion that is used for guiding light internally, yet is capable of reducing the sense of incongruity in the scene that the viewer sees through the emission section. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, the optical element is an optical element that guides external scene light (L1) by internally reflecting it, and includes an entrance surface (2a) on which the external scene light is incident, an exit portion (2b) having a plurality of protruding prism portions (3) and a plurality of flat portions (4) that are flat surfaces, and a smooth surface (2c) opposite the exit portion, and is equipped with a light guide (2) made of a light-transmitting material, the exit portion being provided at a position where the external scene light incident from the entrance surface is incident light (L2), the prism portion has an exit surface (3a) that emits a portion of the incident light to the outside, the flat portion reflects a portion of the incident light toward the smooth surface by total reflection, and the light guide has one or more luminance difference reduction portions (5) between two adjacent prism portions sandwiching the flat portion that emit a portion of the incident light to the outside.

[0008] This optical member has an emission section having a plurality of prism sections and a flat section, and has one or more luminance difference reduction sections that emit a part of light incident to the outside between two adjacent prism sections via the flat sections. When incident light incident from the incident surface into the light guide reaches the emission section, a part of the incident light is emitted to the outside from the prism section, another part of the incident light is guided by total reflection at the flat section, and another part of the incident light is emitted to the outside from the luminance difference reduction section. As a result, the light emitted to the outside from the luminance difference reduction section is added to the gap between the emitted light emitted to the outside from the two adjacent prism sections via the flat sections, reducing the luminance difference in the gap between the adjacent emitted light, and reducing the sense of incongruity of the scene viewed by the viewer.

[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] 3A to 3C are explanatory diagrams of light guide in the optical member according to the first embodiment. [Diagram 3] 2 is an enlarged view of region III in FIG. 1, illustrating the details of light guiding in an exit section. FIG. [Figure 4] FIG. 4 corresponds to FIG. 3 and is an explanatory diagram of the width of a luminance difference reducing portion and a flat portion. [Diagram 5] 5 is a view taken along the arrow V in FIG. 4. [Figure 6] 10A and 10B are explanatory diagrams of light and dark patterns of light rays when the optical member of the comparative example is viewed from the exit portion side. [Figure 7] 4A to 4C are explanatory diagrams of a light and dark pattern of light rays when the optical member of the first embodiment is viewed from the exit portion side. [Figure 8] FIG. 4 is a view corresponding to FIG. 3 and is an enlarged cross-sectional view showing a first modified example of an emission portion of the optical member of the first embodiment. [Figure 9]FIG. 4 is a view corresponding to FIG. 3 and is an enlarged cross-sectional view showing a second modified example of the emission portion of the optical member of the first embodiment. [Figure 10] FIG. 4 is a view corresponding to FIG. 3 and is an enlarged cross-sectional view showing a part of an optical member according to a second embodiment. [Figure 11] FIG. 4 is a view corresponding to FIG. 3 and is an enlarged cross-sectional view showing a first modified example of an emission portion of the optical member of the second embodiment. [Figure 12] FIG. 4 is a view corresponding to FIG. 3 and is an enlarged cross-sectional view showing a second modified example of the emission portion of the optical member of the second embodiment. [Figure 13] FIG. 11 is a cross-sectional view showing an optical member according to a third embodiment. [Figure 14] 14 is an enlarged view of region XIV in FIG. 13, illustrating the details of light guiding in the exit portion. FIG. [Figure 15] FIG. 15 is an enlarged cross-sectional view corresponding to FIG. 14 and showing a modified example of the emission portion of the optical member of the third embodiment. [Figure 16] 13 is an explanatory diagram of an arrangement of a luminance difference reducing portion in an optical member according to a fourth embodiment. FIG. [Figure 17] FIG. 10 corresponds to FIG. 3 and is an enlarged cross-sectional view showing a part of an optical member according to a fifth embodiment. [Figure 18] 10A and 10B are cross-sectional views showing other examples of the incidence surface of the optical member. [Figure 19] 10A and 10B are cross-sectional views showing other examples of the incidence surface of the optical member. [Figure 20] 10A and 10B are cross-sectional views showing other examples of the emission portion of the optical member. 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 this embodiment can be used, for example, as a blind spot auxiliary device that is attached to a member or obstacle that blocks the view of a viewer (i.e., a user) not shown in the figure and creates a blind spot, allowing the viewer to see 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 surface 2b, a smooth surface 2c, and a terminal surface 2d.

[0015] For convenience of explanation, as shown in FIG. 1, the direction along the normal direction to the flat portion 4 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, is 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 2d, that is, the direction in which the light incident from the incident surface 2a is guided, is 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 4, which will be described later, are repeatedly arranged, and is, for example, the direction perpendicular to the extension direction of the prism portions 3 and flat portions 4, 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 viewer on the emission portion 2b side to view the outside view of the blind spot area caused by the light shielding body 100. Note that, for example, in the case of an in-vehicle application, the light shielding body 100 is intended to cause a blind spot area such as an A-pillar of a car, but is not limited thereto and may be appropriately changed.

[0017] Hereinafter, for convenience of explanation, as shown in FIG. 2, the external light incident on the incident surface 2a is referred to as "external scene light L1", the light incident from the incident surface 2a into the light guide 2 is referred to as "incident light L2", and the light emitted from the inside of the light guide 2 to the outside is referred to as "first emitted light L3". In addition, in FIG. 2, the outer contour of the light shielding body 100 to which the optical member 1 is attached is shown by a broken line. As shown in FIG. 3, the light of the incident light L2 that is emitted to the outside from the luminance difference reduction section 5 described later is referred to as "second emitted light L4". In addition, in FIG. 3, for convenience of distinction from other light, the second emitted light L4 and the light of the incident light L2 that reaches the luminance difference reduction section 5 are shown by a broken line. This is the same for FIGS. 8 to 12, 14, 15, and 17 described later.

[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 another part of the incident light L2 is reflected by the flat portion 4, 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 4 is totally reflected by the smooth surface 2c and the flat portion 4, 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 4, 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 4 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 4 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 2d 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 section 2b is formed, for example, at a position adjacent to and intersecting with the incident surface 2a. The emission section 2b has, for example, a plurality of prism sections 3 which are triangular protrusions in a cross-sectional view, a plurality of flat sections 4 which are flat surfaces, and at least one luminance difference reducing section 5 disposed between two adjacent prism sections 3. The emission section 2b is formed, for example, by alternately and repeatedly arranging the protruding prism sections 3 and the flat sections 4 which are flat surfaces from the incident surface 2a toward the terminal surface 2d, and at least one luminance difference reducing section 5 is formed within the flat sections 4.

[0022] The multiple prism portions 3 are protrusions protruding from the flat portion 4, and are arranged, for example, in parallel. In this embodiment, the prism portions 3 have a height in the thickness direction D1 and a width W in the light guide direction D2. P In this specification, "substantially the same" includes not only the case where they are completely the same, but also the case where there is a slight difference due to unavoidable factors such as processing errors, but is almost the same. For example, the widths of both ends of the flat portion 4 sandwiched between two adjacent prism portions 3 in the light guiding direction D2 are W S The width W of the prism part 3 P and the width W of the flat part 4S is constant in the emission portion 2b. In other words, the pitch interval between the adjacent prism portions 3 in the light guiding direction D2 is constant, for example.

[0023] The multiple prism parts 3 have, for example, an exit surface 3a that is parallel to the incident surface 2a in a cross-sectional view and that 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 part of the incident light L2 that reaches the exit surface 3a is emitted to the outside as the first exit light L3 at the same angle θ as the outside scene light L1. Therefore, as seen by a viewer (not shown) positioned on the exit part 2b side, continuity is ensured between the outside scene not passing through the optical member 1 and the outside scene of the blind spot area that is made visible by the optical member 1. For example, the other surface 3b of the multiple prism parts 3 is a flat surface with an inclination angle δ with respect to the thickness direction D1, and the angle δ is appropriately designed so as not to prevent the incident light L2 with the light guide angle φ from heading toward the exit surface 3a. The multiple prism portions 3 may have a light-shielding film (not shown) made of any material that absorbs visible light formed on the other surface 3b to prevent, for example, external light from the emission portion 2b side from penetrating into the light guide 2 from the other surface 3b.

[0024] The flat portions 4 are, for example, flat surfaces facing the smooth surface 2c and arranged substantially parallel to it. In this specification, "substantially parallel" includes not only completely parallel cases, but also cases where there is a slight difference due to processing errors or the like, but are substantially parallel. The flat portions 4 are, for example, arranged on the same plane and form one plane. Since the incident light L2 from the incident surface 2a is incident on the flat portions 4 at an angle equal to or greater than the critical angle, the flat portions 4 function as a reflecting surface that reflects the incident light L2 toward the smooth surface 2c by total reflection. Since the flat portions 4 are portions that do not emit the incident light L2 to the outside, they are portions that have a lower brightness than the exit surface 3a of the prism portion 3 when viewed from a viewer (not shown) located on the exit portion 2b side.

[0025] The plurality of luminance difference reducing sections 5 are provided to reduce the luminance difference between the emergent surface 3a of the prism section 3 and the flat section 4 as viewed from the emergent section 2b, and in turn to reduce the contrast ratio therebetween, thereby reducing the sense of incongruity in the scene viewed by a viewer (not shown). This will be described in detail later.

[0026] At least one luminance difference reduction unit 5 is formed between two adjacent prism parts 3 in the light guide direction D2, as shown in FIG. 3, and emits a part of the incident light L2 to the outside as a second emitted light L4. In other words, the luminance difference reduction unit 5 emits the second emitted light L4 between the two first emitted lights L3 emitted from the two adjacent prism parts 3, that is, into the gap generated by the flat part 4. In this way, the luminance difference reduction unit 5 reduces the luminance change between the area where the first emitted light L3 is emitted and the area where the first emitted light L3 is not generated, and makes the boundary between these areas less noticeable, thereby reducing the discomfort of the visually perceived scene. The luminance difference reduction unit 5 is configured to have, for example, a second emission surface 5a, which is a triangular protrusion smaller than the prism part 3 in a cross-sectional view and parallel to the first emission surface 3a, with the emission surface 3a as the first emission surface. In this case, the luminance difference reduction unit 5 has, for example, an adjacent surface 5b adjacent to the second exit surface 5a, which is a flat surface parallel to the other surface 3b, but is not limited thereto. In this embodiment, the luminance difference reduction unit 5 has a surface on the terminal surface 2d side as the second exit surface 5a, and a surface on the entrance surface 2a side as the adjacent surface 5b.

[0027] 4, the luminance difference reduction section 5 has a distance W0 between two adjacent prism sections 3 in the light guiding direction D2 and a width W1 in the same direction, and it is preferable that W1 is within a range of 7.7% to 39.4% of W0 being 100%. By setting W1 to at least 7.7%, the luminance difference reduction section 5 can obtain the effect of reducing the luminance difference by the second emitted light L4, and by setting W1 to at least 39.4% or less, the amount of the first emitted light L3 on the terminal surface 2d side of the emission section 2b can be secured.

[0028] 5, the luminance difference reduction section 5 extends linearly along the extension direction D3, which is the direction in which the multiple prism sections 3 extend on the plane formed by the flat section 4 when viewed from the emission section 2b side. In other words, the luminance difference reduction section 5 is arranged, for example, with the multiple prism sections 3 arranged in parallel aligned with their extension direction D3, and is formed in a row between two adjacent prism sections 3. Note that the extension direction D3 is perpendicular to the light guide direction D2, as shown in FIG. 5, for example.

[0029] For example, when one luminance difference reduction section 5 is formed between two adjacent prism sections 3, it is preferable to arrange the luminance difference reduction section 5 at approximately the center between the two prism sections 3. For example, as shown in Fig. 3, the portion of the flat section 4 located to the left of the luminance difference reduction section 5 in the light guiding direction D2 is the first flat section 41, and the portion located to the right of the luminance difference reduction section 5 in the same direction is the second flat section 42. In this case, when the luminance difference reduction section 5 is formed so that the widths of the first flat section 41 and the second flat section 42 in the light guiding direction D2 are approximately the same, the second emitted light L4 is emitted approximately at the center of the gap between the adjacent first emitted lights L3, which is preferable, but not limited to this.

[0030] The end surface 2d is a surface that connects the emission portion 2b and the smooth surface 2c. The end surface 2d is, for example, a single flat surface. The inclination of the end surface 2d is arbitrary, but for example, the end surface 2d 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 2d in the emission portion 2b, and function as the last emission surface in the light guiding direction D2.

[0031] In addition, the side surfaces (not shown) of the light guide 2 that 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, and the terminal surface 2d are surfaces that do not contribute optically, and their shapes, configurations, etc. are arbitrary.

[0032] The basic configuration of the optical member 1 has been described above.

[0033] [Effect of the luminance difference reduction section] Next, the effect of the luminance difference reducing section 5 will be described in comparison with an optical member of a comparative example shown in FIG.

[0034] In Fig. 6 and Fig. 7, the incident light L2 and the first exiting light L3 in the optical members 1 and 10 are hatched for the sake of convenience in order to make them easier to see. Also, in Fig. 6 and Fig. 7, bright areas in the scene are shown in white and dark areas are hatched for the sake of making it easier to understand the light and dark pattern of the scene recognized by a viewer (not shown) located on the exit portion 2b side. In Fig. 7, the second exiting light L4 is hatched for the same reason as in Fig. 6.

[0035] 6, the optical member 10 of the comparative example has an emission section having a plurality of prism portions 3 and flat portions 4, which are arranged alternately and repeatedly, and is configured with a light guide 20 made of a light-transmitting material without a luminance difference reducing portion 5. In the optical member 10 of the comparative example, a portion of the incident light L2 is emitted from the prism portions 3 as a first emitted light L3, and the remaining portion of the incident light L2 is totally reflected by the flat portions 4 and guided inside the light guide 20. In the optical member 10 of the comparative example, the first emitted light L3 is emitted from each of the prism portions 3 arranged across the flat portions 4, and the first emitted light L3 reaches the viewpoint of a viewer (not shown), thereby allowing the viewer to view a scene in a blind spot area.

[0036] According to the inventors' intensive study, it was found that in the optical member 10 of the comparative example, the scene viewed through the emission part is "bright" in the area where the first emitted light L3 is generated, and "dark" in the area corresponding to the flat part 4 where the first emitted light L3 is not generated, which may cause a sense of incongruity. Specifically, in the optical member 10 of the comparative example, the luminance difference between the bright area and the dark area is large in the scene viewed through the emission part, and for example, the dark area is recognized by the viewer as a black stripe, and the boundary between light and dark becomes conspicuous, which may cause a sense of incongruity.

[0037] In order to reduce this discomfort, it is conceivable to reduce the gaps in the exit section so that the width of the "dark" area caused by the gaps between adjacent prism parts 3 is less than the human resolution, i.e., cannot be recognized. However, in this case, in order to ensure the amount of light of the first exit light L3 on the terminal face side of the exit section, each prism part 3 must be made small, and the width of each first exit light L3 becomes small. Then, the effect of diffraction in each first exit light L3 becomes large, and the scene viewed by the exit section becomes blurred and unclear, and visibility is reduced.

[0038] In contrast, the optical member 1 of the present embodiment is configured such that a luminance difference reduction section 5 is formed between two adjacent prism sections 3, and the second emitted light L4 is generated from the luminance difference reduction section 5. As a result, the second emitted light L4 is emitted into the gap between the first emitted light L3, and the luminance of the gap between the two adjacent prism sections 3 increases by the amount of the second emitted light L4. Therefore, the scene viewed by the emission section 2b has a reduced luminance difference between the "bright" and "dark" regions compared to the optical member 10 of the comparative example, and thus the contrast ratio of these regions is reduced. As a result, the scene viewed by the emission section 2b has a less noticeable boundary between the "bright" and "dark" regions, reducing the sense of incongruity.

[0039] The second emitted light L4 only needs to have an amount of light that is recognized as light by a viewer (not shown) or more, and does not need to have an amount of light that is recognized as a clear scene.

[0040] According to this embodiment, the optical member 1 has a luminance difference reduction section 5 in which the emission section 2b has a plurality of prism sections 3 and a flat section 4, and emits a part of the light incident to the outside between two adjacent prism sections 3 via the flat section 4. In the optical member 1, a part of the incident light L2 that reaches the emission section 2b is emitted to the outside from the prism section 3 as the first emitted light L3, another part is guided by total reflection at the flat section 4, and another part is emitted to the outside from the luminance difference reduction section 5 as the second emitted light L4. As a result, the second emitted light L4 is added to the gap between the first emitted light L3 from the two adjacent prism sections, and the luminance difference in the gap between the first emitted light L3 is reduced, resulting in an optical member 1 in which the sense of incongruity of the scene viewed by the viewer is reduced. In addition, the optical member 1 has the following effects.

[0041] (1) The optical member 1 is configured such that the second exit light L4 is emitted in the same direction as the first exit light L3, by the luminance difference reduction section 5 having the second exit surface 5a parallel to the first exit surface 3a of the prism section 3. As a result, in the optical member 1, the second exit light L4 emitted from the luminance difference reduction section 5 reaches the viewer's viewpoint together with the first exit light L3, and the luminance difference in the light and dark pattern caused by the pattern structure of the prism section 3 and the flat section 4 is further reduced, and the sense of incongruity in the viewed scene is further reduced.

[0042] (2) The optical member 1 may be configured such that the width W1 in the light guiding direction D2 of the luminance difference reduction portion 5 is within a range of 7.7% to 39.4% of the distance W0 between two adjacent prism portions 3. In this case, the optical member 1 can ensure the amount of the first emitted light L3 on the terminal surface 2d side of the emission portion 2b while reducing the sense of incongruity caused by the pattern structure of the emission portion 2b.

[0043] (Modification of the first embodiment) The optical member 1 may have a configuration in which two luminance difference reducing sections 5 are formed between two adjacent prism sections 3 in the light guiding direction D2, as shown in FIG. 8, for example. In this case, as shown in FIG. 8, for example, among the multiple regions of the flat section 4 partitioned by the luminance difference reducing sections 5, the first flat section 41, the second flat section 42, and the third flat section 43 are arranged in order from the left side to the right side in the light guiding direction D2. In this case, the luminance difference reducing sections 5 are formed in the optical member 1 so that the widths of the first flat section 41, the second flat section 42, and the third flat section 43 in the light guiding direction D2 are approximately the same, but this is not limited to this. In this way, the number of luminance difference reducing sections 5 formed between two adjacent prism sections 3 in the optical member 1 may be one or more, and may be changed as appropriate. The multiple luminance difference reducing sections 5 are, for example, linearly extended along the extension direction D3 of the prism section 3, and arranged in parallel along the light guiding direction D2.

[0044] In addition, it is preferable that the optical member 1 has, for example, the width of the two luminance difference reduction sections 5 in the light guide direction D2 be 7.7% or more of the distance W0 between two adjacent prism sections 3, and that the total width be within the range of 39.4% or less of W0.

[0045] 9, the optical member 1 may have a luminance difference reduction portion 5 that is a recess recessed from the flat portion 4 and has a groove shape extending linearly along the extension direction D3 of the prism portion 3. In this case, the luminance difference reduction portion 5 has a second exit surface 5a on the incident surface 2a side that is parallel to the first exit surface 3a, and emits a part of the incident light L2 from the second exit surface 5a as a second exit light L4.

[0046] The above modification also provides an optical member 1 that can obtain the same effects as those of the first embodiment. Note that the optical member 1 of this modification may have a configuration having a plurality of groove-shaped luminance difference reducing portions 5 between two adjacent prism portions 3, or may have a configuration in which protruding luminance difference reducing portions 5 and groove-shaped luminance difference reducing portions 5 are mixed.

[0047] Second embodiment The optical member 1 of the second embodiment will be described with reference to the drawings.

[0048] The optical member 1 of this embodiment differs from that of the first embodiment in that the shape of the luminance difference reducing portion 5 is changed, as shown in Fig. 10 for example. In this embodiment, this difference will be mainly described.

[0049] In this embodiment, the luminance difference reduction unit 5 is, for example, a protrusion with a curved surface and a substantially hemispherical shape in a cross-sectional view, and extends along the extension direction D3 of the prism unit 3. The luminance difference reduction unit 5, for example, emits a part of the incident light L2 to the outside in a plurality of directions as the second emitted light L4 by the curved surface. In other words, in this embodiment, the luminance difference reduction unit 5 has a shape of a convex lens whose curved surface functions as a lens for emitting the second emitted light L4. In this embodiment, a part of the second emitted light L4 emitted in a plurality of directions reaches the viewpoint of a viewer (not shown) together with the first emitted light L3, thereby reducing the sense of incongruity of the scene caused by the pattern structure of the emission unit 2b.

[0050] The optical member 1 of this embodiment also provides the same effects as those of the first embodiment.

[0051] (Modification of the second embodiment) 11, the optical member 1 may have two or more luminance difference reducing portions 5 formed between two adjacent prism portions 3. Alternatively, the optical member 1 may have a recess recessed from the flat portion 4 and a groove extending linearly along the extension direction D3 of the prism portions 3, as shown in FIG.

[0052] The above modification also provides an optical member 1 that can obtain the same effect as in the above embodiment 2. Note that the optical member 1 of this modification may have a configuration having a plurality of groove-shaped luminance difference reducing portions 5 between two adjacent prism portions 3, or may have a configuration in which protruding luminance difference reducing portions 5 and groove-shaped luminance difference reducing portions 5 are mixed.

[0053] Third embodiment The optical member 1 of the third embodiment will be described with reference to the drawings.

[0054] The optical member 1 of this embodiment differs from that of the first embodiment in that the configuration of the emission section 2b is changed, for example, as shown in Fig. 13. In this embodiment, this difference will be mainly described.

[0055] In the present embodiment, as shown in FIG. 14, the emission section 2b has one luminance difference reducing section 5 between two adjacent prism sections 3, and the flat section 4 has a substantially stepped configuration having a first flat section 41 and a second flat section 42 that are different in position in the thickness direction D1. As a result, the incident light L2 incident on the flat section 4 is divided and reflected by the first flat section 41 and the second flat section 42, and the pitch interval between the reflected light at the first flat section 41 and the reflected light at the second flat section 42 is significantly different from the interval between the two adjacent prism sections 3. Then, the reflected light at the first flat section 41 and the reflected light at the second flat section 42 are reflected by the smooth surface 2c, and when they reach the region of the emission section 2b closer to the terminal surface 2d, the pitch interval between these reflected lights is not slightly shifted from the interval between the two adjacent prism sections 3. As a result, the optical element 1 suppresses the occurrence of moire caused by a slight misalignment between the reflected light pitch of the incident light L2 at the flat portion 4 and the pitch interval of the prism portion 3, making the scene viewed through the exit portion 2b easier to see.

[0056] In this embodiment, the flat portion 4 has a stepped shape in which the second flat portion 42 on the terminal surface 2d side is located closer to the tip of the prism portion 3 than the first flat portion 41. In other words, the smooth surface 2c side in the thickness direction D1 is considered to be the top and the opposite side is considered to be the bottom, and the flat portion 4 is configured such that the position in the thickness direction D1 of the area closer to the terminal surface 2d among the multiple areas partitioned by the luminance difference reducing portion 5 becomes lower. As a result, the optical member 1 is configured to be able to enlarge the prism portion 3, thereby ensuring a wide first exit surface 3a, while suppressing the occurrence of the above-mentioned moire.

[0057] In this embodiment, the luminance difference reduction unit 5 is formed at an end of the second flat portion 42 located at a step portion with the first flat portion 41. The luminance difference reduction unit 5 is, for example, a triangular protrusion protruding from the second flat portion 42 in a cross-sectional view, and the surface on the second flat portion 42 side is the second exit surface 5a, and the second exit light L4 from the second exit surface 5a is emitted in the same direction as the first exit light L3. The luminance difference reduction unit 5 is, for example, shaped such that the surface opposite to the second exit surface 5a is continuous with the step surface between the first flat portion 41 and the second flat portion 42 and forms one surface together with the step surface. The luminance difference reduction unit 5 is, for example, formed so that the widths of the first flat portion 41 and the second flat portion 42 in the light guide direction D2 are approximately the same, but is not limited thereto.

[0058] The optical member 1 of this embodiment also provides the same effect as that of the first embodiment. In addition, in the optical member 1, the flat portion 4 is composed of the first flat portion 41 and the second flat portion 42 that are located at different positions in the thickness direction D1, so that the occurrence of moire can be suppressed on the side of the terminal end surface 2d of the emission portion 2b, and the effect of improving the visibility of the scene can be obtained.

[0059] (Modification of the third embodiment) 15, the optical member 1 may have a first flat portion 41, a second flat portion 42, and a third flat portion 43 that are located at different positions in the thickness direction D1 from the incident surface 2a side toward the terminal surface 2d side in the light guiding direction D2. In this case, the luminance difference reducing portions 5 are formed in the same number as the number of steps in the flat portion 4, for example, and are formed linearly along the extension direction D3, one at each step portion.

[0060] The flat portion 4 has a stepped shape in which the first flat portion 41, the second flat portion 42, and the third flat portion 43 are arranged in this order, that is, the area closer to the terminal end surface 2d is located lower in the thickness direction D1. The first flat portion 41, the second flat portion 42, and the third flat portion 43 have, for example, approximately the same width in the light guide direction D2, but are not limited to this.

[0061] The luminance difference reduction section 5 is formed, for example, at the end of the second flat section 42 on the incident surface 2a side and the end of the third flat section 43 on the incident surface 2a side, and emits the second exit light L4 from the second exit surface 5a on the terminal surface 2d side.

[0062] This modified example also provides the optical member 1 that can obtain the same effects as those of the third embodiment. The number of steps in the flat portion 4 and the number of luminance difference reducing portions 5 may be three or more.

[0063] (Fourth embodiment) The optical member 1 of the fourth embodiment will be described with reference to the drawings.

[0064] The optical member 1 of this embodiment differs from the above-described first embodiment in that a plurality of luminance difference reducing portions 5 are formed between two adjacent prism portions 3, and their arrangement is changed, as shown in, for example, Fig. 16. In this embodiment, this difference will be mainly described.

[0065] In this embodiment, the plurality of luminance difference reducing parts 5 are each smaller in width in the light guiding direction D2 and height in the thickness direction D1 than the prism part 3, as shown in FIG. 16, and are distributed and arranged in the flat part 4. For example, one of the plurality of luminance difference reducing parts is arranged at the approximate center of the flat part 4 in the light guiding direction D2, and two of the other parts are arranged so as to divide the flat part 4 into approximately equal widths in the light guiding direction D2, and these parts are arranged alternately along the extension direction D3 to form a pattern. As a result, the second emitted light L4 is distributed and emitted from one flat part 4, and luminance unevenness in the dark area of ​​the scene viewed by the emission part 2b is reduced. As a result, the optical member 1 has an effect of further reducing the luminance difference between the light and dark areas in the scene viewed by the emission part 2b, making the boundaries between them less noticeable, and further reducing the sense of incongruity in the scene.

[0066] In addition, the multiple brightness difference reduction sections 5 only need to be able to overall disperse the second emitted light L4 in one flat section 4, and are not limited to the pattern arrangement described above, but may be arranged randomly or in other pattern arrangements, and the arrangement may be changed as appropriate.

[0067] The present embodiment also provides the optical member 1 that can obtain the same effects as the above-described first embodiment. Moreover, the plurality of luminance difference reducing parts 5 are formed on each of the plurality of flat parts 4, and the plurality of luminance difference reducing parts 5 are arranged in the above-described pattern or in another arrangement, and the second emitted light L4 is dispersed, thereby providing the optical member 1 that can further reduce the sense of incongruity in the scene visually recognized by the emission part 2b.

[0068] Fifth embodiment The optical member 1 of the fifth embodiment will be described with reference to the drawings.

[0069] The optical member 1 of this embodiment differs from that of the first embodiment in that the shape of the luminance difference reducing portion 5 is changed, as shown in Fig. 17 for example. In this embodiment, this difference will be mainly described.

[0070] In this embodiment, the luminance difference reduction section 5 is, for example, a rough surface section that scatters a part of the incident light L2 and emits the second emitted light L4 in multiple directions. As a result, a part of the second emitted light L4 emitted in multiple directions reaches the viewpoint of a viewer (not shown) together with the first emitted light L3, thereby reducing the luminance difference of the light and dark pattern of the scene viewed by the emission section 2b, and reducing the sense of incongruity caused by this. The luminance difference reduction section 5 can be formed, for example, by molding a light guide without the luminance difference reduction section 5 using a mold and resin material (not shown), and then performing any roughening process such as plasma processing or laser processing.

[0071] The optical member 1 of this embodiment also provides the same effects as those of the first embodiment.

[0072] (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.

[0073] For example, the optical member 1 may have a configuration in which a part or all of the luminance difference reducing portion 5 in the fourth embodiment is a curved protrusion or recess similar to the second embodiment or its modified example, or a rough surface portion similar to the fifth embodiment. In this way, the optical member 1 may have a form that combines the components of each of the above embodiments and their modified examples, as well as other embodiments described below, except when it is clearly difficult to achieve both. In other words, the optical member 1 may have one or more discontinuous surfaces that do not satisfy the total reflection condition between two adjacent prism portions 3 with a flat portion 4 in between, and emit the second emitted light L4 from the discontinuous surfaces.

[0074] (2) In each of the above-described embodiments and the modified examples, the optical member 1 may be configured such that a part of the incident surface 2a protrudes upward in the thickness direction D1 beyond the smooth surface 2c, as shown in FIG. 18, for example. In this case, the optical member 1 has an inclined surface 2e at a portion of the incident surface 2a that connects the end of the incident surface 2a opposite to the emission portion 2b with the smooth surface 2c. The inclined surface 2e may be, for example, a single flat surface, but may have any shape. By configuring the optical member 1 such that a part of the incident surface 2a protrudes beyond the smooth surface 2c, the area of ​​the incident surface 2a is increased, and the area of ​​the emission portion 2b where the incident light L2 from the incident surface 2a first reaches can be widened.

[0075] (3) In each of the above embodiments and the modified examples, the optical member 1 may be configured with a plurality of prism portions 6, as shown in Fig. 19, in which the incident surface 2a faces the exit portion 2b together with the smooth surface 2c in a substantially parallel manner and protrudes upward in the thickness direction D1 beyond the smooth surface 2c. In this case, the optical member 1 further has an incident side surface 2f connecting the incident surface 2a and the exit portion 2b, and is configured to allow external scene light L1 to enter the inside from one surface 6a of the plurality of prism portions 6 opposite to the smooth surface 2c.

[0076] (4) In each of the above embodiments and their modified examples, the optical member 1 may have a plurality of regions in which the width ratio of the prism portion 3 and the flat portion 4 in the light guide direction D2 is different, as shown in FIG. 20, for example. For example, the emission portion 2b may be composed of three regions: a first region 2ba in which the width ratio of the flat portion 4 is about 66%, a second region 2bb in which the width ratio of the flat portion 4 is about 50%, and a third region 2bc composed only of the prism portion 3. In this case, the ratio of the flat portion 4 is the reflectance of the incident light L2 in each region of the emission portion 2b, and the remainder is the emission rate. Then, the emission rates of the first region 2ba, the second region 2bb, and the third region 2b3 are approximately the same at about 33%, and the brightness unevenness of the scene viewed by the emission portion 2b is suppressed. The number of regions constituting the emission portion 2b is arbitrary, and the width ratio of the flat portion 4 in each region is appropriately designed so that the emission rates are approximately the same depending on the number of regions. In this case, at least one luminance difference reducing portion 5 is formed between two adjacent prism portions 3 with the flat portion 4 in between, and is not formed in an area constituted by the prism portion 3 alone.

[0077] (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]

[0078] 2...Light guide, 2a...Incidence surface, 2b...Emission part, 2c...Smooth surface, 3...Prism part 3a...first exit surface, 4...flat portion, 4...luminance difference reducing portion, 5a...second exit surface, D1...thickness direction D2...Light guiding direction, L1...Outside light, L2...Incoming light W0: Distance between adjacent prism parts in the light guide direction W1: Width of the luminance difference reduction section in the light guide direction

Claims

1. An optical member that internally reflects and guides external light (L1), The light guide (2) includes an incident surface (2a) on which the external light is incident, an exit portion (2b) having a plurality of protruding prism portions (3) and a plurality of flat portions (4) that are flat surfaces, and a smooth surface (2c) facing the exit portion, and is made of a light-transmitting material; The emission portion is provided at a position where the external scene light incident from the incident surface is incident light (L2), and the incident light is incident, The prism portion has an exit surface (3 a) that emits a part of the incident light to the outside, the flat portion reflects a part of the incident light toward the smooth surface by total reflection, The light guide is an optical member having one or more luminance difference reducing sections (5) between two adjacent prism sections with the flat section interposed therebetween, the luminance difference reducing sections (5) outputting a portion of the incident light to the outside.

2. The optical member according to claim 1 , wherein the luminance difference reducing portion has a second exit surface (5a) parallel to the exit surface, the first exit surface being the exit surface.

3. The optical member according to claim 1 , wherein the luminance difference reducing portion has a curved surface, and emits a part of the incident light to the outside from the curved surface.

4. The optical member according to claim 1 , wherein the luminance difference reducing portion is a rough surface portion that scatters a portion of the incident light and emits the scattered light to the outside.

5. The optical member according to claim 1 , wherein the luminance difference reducing portion is provided between two of the prism portions adjacent to each other with the flat portion interposed therebetween, and extends along a direction in which the adjacent prism portions extend.

6. A direction perpendicular to the extension direction of the prism portion and in which the plurality of prism portions are arranged is defined as an arrangement direction (D2), the luminance difference reducing portion is provided between two adjacent prism portions with the flat portion interposed therebetween, and is arranged along an extension direction of the adjacent prism portions, The optical member according to claim 1 , wherein at least a portion of the luminance difference reducing portions is located at a different position in the arrangement direction from other luminance difference reducing portions.

7. The optical member according to claim 1 , wherein the luminance difference reducing portion is smaller in size than the prism portion, and is a protrusion protruding from the flat portion or a recess recessed from the flat portion.

8. A direction along a normal direction to the smooth surface and connecting the smooth surface and the flat portion is defined as a thickness direction (D1), the flat portion is located at a position in the thickness direction different from another flat portion located on an opposite side of the luminance difference reducing portion, The luminance difference reducing portion is the optical member according to claim 1 .

9. a direction perpendicular to the extension direction of the prism portion, in which the plurality of prism portions are arranged, is defined as an arrangement direction (D2); a distance (W0) in the arrangement direction between two of the prism portions adjacent to each other via the luminance difference reduction portion is defined as 100%, The optical member according to claim 1 , wherein a width (W1) of the luminance difference reducing portion in the arrangement direction is within a range of 7.7% to 39.4%.

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