Optical member

Abstract

To provide an optical member of half-mirrorless structure, in which the moire attributable to the cyclic structure between the emission and reflection parts of incident light is reduced.SOLUTION: The optical member comprises a light-guide body 2 having an incidence plane 2a, an emission part 2b having a plurality of prism parts 3, and a smooth surface 2c facing the emission part. The smooth surface 2c reflects some of incident light from the incidence plane 2a to the emission part 2b side by total reflection. The emission part 2b has a plurality of regions 2ba to 2bc in which prism parts 3 are repeatedly arranged. The pitch interval of the prism parts 3 differs for each region 2ba to 2bc. It is assumed that the pitch interval of the prism parts 3 in one region of the emission part 2b is P1, the pitch interval of the prism parts 3 in an adjacent region to the one region is P2, and a change amount of the pitch interval of light when specific reflected light having been reflected in a region of the pitch interval P1 has reached the adjacent region is ΔP. The light-guide body 2 satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N represents a positive integer.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, an example of this type of optical member is that described in Patent Document 1. The optical member described in Patent Document 1 is composed of a translucent light guide, and a part of external light incident from the incident surface of the light guide is guided by total reflection inside and is emitted to the outside from an exit surface different from the incident surface, allowing a user on the exit surface side to view an external scene in a 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 exit surface side, and reduces loss of external light due to absorption by 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] However, as a result of careful investigation by the present inventors, it was found that the optical element described in Patent Document 1 may generate moire due to a periodic structure in which prism portions that emit a portion of the incident light and flat portions that reflect a portion of the incident light by total internal reflection are arranged alternately and repeatedly.

[0005] In view of the above, an object of the present disclosure is to provide an optical member that has a half-mirrorless structure while being capable of reducing moire caused by a periodic structure between the emission portions and the reflection portions on the surface from which incident light is emitted. [Means for solving the problem]

[0006] An optical member according to a first aspect of the present disclosure is an optical member that internally reflects and guides external scene light, the optical member comprising: an incident surface (2a) on which external scene light is incident; an exit portion (2b) having a plurality of protruding prism portions (3) and extending in a direction intersecting the incident surface; a smooth surface (2c) facing the exit portion; reflecting surfaces (4, 5) facing the smooth surface; and an end surface (2e) located on the opposite side to the incident surface and connecting the exit portion and the smooth surface, the optical member comprising a light guide (2) made of a light-transmitting material, the smooth surface reflecting a portion of incident light (L2) from the incident surface towards the exit portion by total reflection, the exit portion having a plurality of regions (2ba, 2bb, 2bc) in which the prism portions are repeatedly arranged, the plurality of regions being formed of prism portions (3a, 3b, 3bc) each having a plurality of protruding prism portions (3a, 3b, 3bc) each having a plurality of protruding prism portions (3b ... The pitch intervals of the prism portions are different, the direction along one plane of the smooth surface from the incident surface toward the terminal surface is defined as the light guiding direction (D2), the pitch interval between two adjacent prism portions in one of the multiple regions is defined as P1, another region adjacent to the one region along the light guiding direction is defined as an adjacent region, the pitch interval between two adjacent prism portions in the adjacent region is defined as P2, light of the incident light reflected at the region with pitch interval P1 is defined as specific reflected light, and the amount of change in the pitch interval of the specific reflected light in the light guiding direction when the specific reflected light reaches the adjacent region is defined as ΔP, and the light guide satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer.

[0007] This optical member includes a light guide having an incident surface, an exit portion, a smooth surface and a reflective surface facing each other, and a terminal surface connecting the exit portion and the smooth surface, and the smooth surface reflects a part of the incident light from the incident surface by total reflection, so that the optical member has a half-mirrorless structure. This optical member includes a plurality of prism portions in which the exit portions are repeatedly arranged, and has a plurality of regions with different pitch intervals of the prism portions. In addition, the direction along one plane of the smooth surface, from the incident surface toward the terminal surface, is taken as the light guide direction, and among the plurality of regions, an adjacent region adjacent in the light guide direction to a region with a pitch interval of the prism portions having a pitch interval of P1 has a pitch interval of P2 of the prism portions. Then, the light reflected in the region with a pitch interval of P1 out of the incident light is taken as specific reflected light, and the amount of change in the pitch interval of the specific reflected light in the light guide direction when the specific reflected light reaches the adjacent region is taken as ΔP. ​​In this case, the light guide satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer, to reduce moire. Therefore, this optical member has a half-mirrorless structure, while reducing moire caused by the periodic structure between the exit portions and the reflecting portions of incident light on the exit surface.

[0008] Moreover, an optical member according to a second aspect of the present disclosure is an optical member that internally reflects and guides external scene light, and includes an entrance surface (2a) into which external scene light is incident, a reflective exit surface (2f) that is arranged opposite to the entrance surface but not adjacent to the entrance surface, and emits a portion of the incident light (L2) from the entrance surface to the outside, and a reflecting surface (2g) that is arranged adjacent to the entrance surface and reflects light from the reflective exit surface, and a reflecting surface (2g) that is adjacent to the reflective exit surface and arranged opposite the reflecting surface, and emits a portion of the incident light (L2) from the entrance surface to the outside. The light guide (2) is made of a light-transmitting material and includes a smooth exit surface (2h) that reflects a portion of the light reflected by the reflecting surface and emits the remainder to the outside, an incident side surface (2i) that connects the incident surface and the reflecting exit surface, and a terminal surface (2e) that is located on the opposite side to the incident side and connects the reflecting surface and the smooth exit surface. The reflecting exit surface includes a plurality of first prism portions (6) that reflect incident light toward the reflecting surface and have first reflecting portions (6a) that are inclined with respect to the incident surface, and a flat the light guide body is configured such that a plurality of first flat portions (7) which are flat surfaces are alternately arranged, and the reflective surface has a plurality of second prism portions (8) having second reflective portions (8a) which reflect a portion of the light reflected at the reflective exit surface towards the smooth exit surface, and a plurality of second flat portions (9) which are flat surfaces which reflect the remainder of the reflected light by total reflection; the direction along the incident surface from the incident side surface towards the terminal surface is defined as the light guide direction (D2); the pitch interval of two adjacent first prism portions in the light guide direction is defined as P1; the pitch interval of two second prism portions in the light guide direction into which reflected light from two first prism portions of the reflective surface having pitch interval P1 is incident is defined as P2; the light of the incident light which is reflected at the reflective exit surface is defined as specific reflected light; the amount of change in the pitch interval of the light in the light guide direction when the specific reflected light reaches the reflective surface is defined as ΔP; and the light guide body satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer.

[0009] The optical member includes a light guide having an incident surface and a reflecting surface arranged adjacent to each other, a reflecting exit surface and a smooth exit surface arranged opposite the incident surface and the reflecting exit surface, an incident side surface connecting the incident surface and the reflecting exit surface, and a terminal surface connecting the reflecting surface and the smooth exit surface. The light guide has a reflecting exit surface formed by alternatingly arranging a plurality of first prism portions and a first flat portion, and a reflecting surface formed by a plurality of second prism portions and a plurality of second flat portions, and the second flat portion reflects the reflected light from the first reflecting portion toward the smooth exit surface by total reflection. In addition, the pitch interval of the first prism portions in the light guide direction is P1, and the pitch interval of the second prism portions in the light guide direction is P2, with the light guide direction being a direction along one plane formed by the incident surface from the incident side surface toward the terminal surface. Then, the amount of change in the light pitch when the specific reflected light reflected from the reflection exit surface reaches the reflection surface is denoted as ΔP, and the light guide satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer, thereby reducing moire. Therefore, this optical member has a half-mirrorless structure, while reducing moire caused by the periodic structure between the exit portion and the reflection portion of the incident light on the exit surface.

[0010] 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]

[0011] [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] 10A to 10C are explanatory diagrams of changes in a light pattern inside an optical member of a comparative example and occurrence of moire due to a structural pattern. [Figure 4] 10 is an explanatory diagram of emitted light incident on the eye of a viewer located on the emission side of the optical member and the distance from the emission part to the viewer's eye. FIG. [Diagram 5]5 is an explanatory diagram for explaining the design of the angle difference between the two emitted light beams shown in FIG. 4 and the pitch interval of the prism portions in the optical member according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing an optical member according to a second embodiment. [Figure 7] 7 is an explanatory diagram of light guide in the optical member of FIG. 6. [Figure 8] FIG. 11 is a cross-sectional view showing a first modified example of the optical member of the second embodiment. [Figure 9] FIG. 13 is a diagram illustrating a second modified example of the optical member of the second embodiment, and is an enlarged cross-sectional view illustrating the vicinity of the reflective layer and the prism portion. [Figure 10] FIG. 11 is a cross-sectional view showing an optical member according to a third embodiment. [Figure 11] 11 is an explanatory diagram of light guide in the optical member of FIG. 10. [Figure 12] 4 is an explanatory diagram of external emission and internal reflection of incident light on a reflective exit surface. FIG. [Figure 13] 4A to 4C are diagrams illustrating reflection of incident light at a reflecting surface and a smooth exit surface, and emission of incident light to the outside at the smooth exit surface. [Figure 14] FIG. 11 is a cross-sectional view showing a modified example of the optical member of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] (First embodiment) The optical member 1 of the first embodiment will be described with reference to the drawings. 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 the user's field of vision and creates a blind spot, and allows the user to visually recognize the scene in the blind spot. For example, in the case of an in-vehicle application, the optical member 1 is attached to a pillar of the vehicle on which it is mounted, and guides external light from the blind spot area caused by the pillar to the user's side, allowing the user to visually recognize the scene in the blind spot area.

[0014] The optical member 1 of this embodiment is composed of a light guide 2 made of a light-transmitting material, as shown in FIG. 1, and includes an incident surface 2a, an exit portion 2b, a smooth surface 2c, an inclined surface 2d, and an end surface 2e. As shown in FIG. 2, the optical member 1 is attached so that the smooth surface 2c faces another member 100, and external light is incident from the incident surface 2a. The optical member 1 is configured such that a part of the light incident from the incident surface 2a to the inside is reflected by the exit portion 2b, and the light reflected by the exit portion 2b is reflected by the smooth surface 2c and directed again toward the exit portion 2b side. The optical member 1, for example, guides external light from the incident surface 2a inside the light guide 2 and emits it to the outside from the exit portion 2b, allowing a user on the exit portion 2b side to view the outside view of the blind spot area caused by the other member 100. In addition, the other member 100 is, for example, in the case of in-vehicle use, a blind spot area is generated in the A-pillar of a car, but is not limited to this and can be changed as appropriate.

[0015] 2, for convenience of explanation, external light incident on the incident surface 2a is referred to as "external scene light L1," light incident from the incident surface 2a into the light guide 2 is referred to as "incident light L2," and light emitted from the inside of the light guide 2 to the outside is referred to as "emitted light L3." In addition, a direction along a normal direction to the smooth surface 2c of the optical member 1 and connecting the emission portion 2b and the smooth surface 2c is referred to as a "thickness direction D1," and a direction perpendicular to the thickness direction D1 and extending from the incident surface 2a toward the terminal surface 2e is referred to as a "light guiding direction D2."

[0016] The light guide 2 is a substantially plate-shaped single member made of a light-transmitting material such as a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, or acrylic, or a glass. The light guide 2 is formed, for example, by a known resin molding method using a mold or the like (not shown). As shown in FIG. 2, the light guide 2 is configured such that a part of the incident light L2 from the incident surface 2a is incident on a prism portion 3 of the exit portion 2b, which will be described later, and the remaining part of the incident light L2 is reflected by a flat portion 4, which will be described later, and this reflected light is directed toward the smooth surface 2c. The light guide 2 is designed so 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.

[0017] sinφ>1 / n (1) As a result, even without a half mirror, part of the incident light L2 in the light guide 2 is repeatedly reflected between the flat portion 4 and the smooth surface 2c, and the incident light L2 is emitted to the outside from an emission surface 3a (described later) of the prism portion 3. The light guide angle φ corresponds to the angle between the traveling direction of the incident light L2 and the thickness direction D1.

[0018] As shown in FIG. 2, the incident surface 2a is a surface that allows the external scene light L1 to enter the inside. The incident surface 2a is adjacent to the exit portion 2b and is a surface along 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, assuming that the angle of the external scene light L1 with respect to the thickness direction D1 is θ, if 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 scene 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 scene 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.

[0019] The light emitting portion 2b is formed at a position adjacent to and intersecting the incident surface 2a, and includes a plurality of prism portions 3, which are triangular protrusions in a cross-sectional view, for example, and a plurality of flat portions 4. The light emitting portion 2b is composed of, for example, a plurality of regions having different pitch intervals (hereinafter simply referred to as "pitch intervals") in the light guiding direction D2 between the prism portions 3. Specifically, the light emitting portion 2b includes, for example, a first region 2ba and a second region 2bb in which the prism portions 3 and the flat portions 4 are alternately and repeatedly arranged, and a third region 2bc in which only the prism portions 3 are continuously and repeatedly arranged. The light emitting portion 2b is, for example, the first region 2ba, the second region 2bb, and the third region 2bc from the incident surface 2a toward the end surface 2e. The regions 2ba to 2bc satisfy, for example, W = 2T·tanφ, where W is the width in the light guiding direction D2 and T is the height in the thickness direction D1 between the flat portion 4 and the smooth surface 2c of the light emitting portion 2b. That is, the regions 2ba to 2bc have, for example, the same width as the distance traveled in the light guiding direction D2 when the incident light L2 makes a round trip between the light emitting portion 2b and the smooth surface 2c. In the first region 2ba and the first region 2ba, the pitch intervals between the prism portions 3 are P1 and P2 (<P1), respectively. The first region 2ba and the first region 2ba are designed so that P1 and P2 satisfy a predetermined relationship for moire reduction. Details of this will be described later.

[0020] In this embodiment, the prism parts 3 are protrusions protruding from the flat part 4, and have, for example, approximately the same height in the thickness direction D1. In this specification, "approximately the same" includes a case where they are completely the same, as well as a case where there is a slight difference due to unavoidable factors such as processing errors, but are almost the same. For example, the 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 an adjacent surface 3b adjacent to the exit surface 3a. For example, the exit surface 3a of the 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 exit light L3 at the same angle θ as the outside scene light L1. Therefore, as seen from the user 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 in the blind spot area that is made visible by the optical member 1. The multiple prism portions 3 are arranged at different pitch intervals in the first region 2ba, the second region 2bb, and the third region 2bc.

[0021] The flat portions 4 are, for example, flat surfaces arranged parallel to and facing the smooth surface 2c. The flat portions 4 are, for example, arranged on the same plane to form one plane. Since the incident light L2 from the incident surface 2a is incident at an angle equal to or larger 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.

[0022] The smooth surface 2c is a single flat surface disposed opposite the emission portion 2b. The smooth surface 2c reflects the light reflected by the flat portion 4 of the incident light L2 toward the emission portion 2b by total reflection. The smooth surface 2c is a surface paired with the flat portion 4, and repeatedly reflects a portion of the incident light L2 between the smooth surface 2c and the flat portion 4, causing the incident light L2 to enter the entire area of ​​the emission portion 2b. In other words, the smooth surface 2c is a portion that serves as a second reflecting surface with the flat portion 4 serving as a first reflecting surface, and serves to guide a portion of the incident light L2 along the light guide direction D2.

[0023] The inclined surface 2d is a surface connecting the incident surface 2a and the smooth surface 2c, and is inclined so that it approaches the terminal surface 2e as it approaches the smooth surface 2c, and is a surface that protrudes more than 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 of one prism portion formed by the incident surface 2a and the inclined surface 2d in the thickness direction D1 is greater than the height T from the exit portion 2b to the smooth surface 2c. This allows the light guide 2 to widen the area in the exit portion 2b where the incident light L2 from the incident surface 2a first arrives. The inclined surface 2d is, for example, one flat surface inclined at an angle ξ with respect to the thickness direction D1. In order to prevent a gap from occurring between the light L2 incident from the entrance surface 2a that passes through the vicinity of the boundary between the smooth surface 2c and the inclined surface 2d and the light reflected on the smooth surface 2c in the vicinity of the boundary, the light guide 2 is designed to satisfy ξ<φ. This prevents a gap from occurring in the outside view that the user views at the exit portion 2b, and ensures the continuity of the display.

[0024] The inclined surface 2d does not have to be a single flat surface as long as the angle ξ of a virtual line connecting the end of the incident surface 2a on the opposite side to the emission section 2b and the end of the smooth surface 2c on the incident surface 2a side with respect to the thickness direction D1 satisfies ξ<φ. For example, the inclined surface 2d may be a polygonal surface having two or more flat surfaces, or may be a single curved surface, and the shape thereof is arbitrary.

[0025] 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.

[0026] In addition, the outer surfaces of the light guide 2 located at both ends in the direction perpendicular to the plane of the paper in Fig. 1, i.e., the side surfaces connecting the entrance surface 2a, the exit surface 2b, the smooth surface 2c, the inclined surface 2d, and the end surface 2e, are surfaces that do not contribute optically, and therefore the configuration thereof is arbitrary. For example, the side surfaces of the light guide 2 may be exposed to the outside without being covered with other materials, or may be configured to prevent light from entering the light guide 2 from the outside by any method, such as covering them with a light absorbing film (not shown).

[0027] The basic configuration of the optical member 1 has been described above.

[0028] [Prism pitch and moire reduction] Next, the occurrence of moire caused by the pitch interval of the prism portions 3 in the exit portion 2b and a design for reducing this will be described.

[0029] As a comparative example, a structure in which the pitch spacing of the prism portions 3 in the emission portion 2b is all constant was used. As a result of careful investigation by the inventors, it was found that moire occurs in the comparative example structure due to the periodic structure of the prism portions 3.

[0030] Specifically, in the structure of the comparative example, the region of the emission section where the incident light L2 from the incident surface 2a is directly incident is defined as the first region, and the region where the light reflected in the first region is reflected by a smooth surface and incident a second time is defined as the second region, and the pitch intervals of the prism portions 3 in the first region and the second region are the same. The pattern of the incident light L2 incident on the first region being emitted to the outside and reflected inside is defined as the light beam pattern, and the light beam pattern in the first region is such that light and dark are alternately repeated at regular intervals, as shown in Fig. 3 for example. The light beam pattern in the first region is the same as the structural pattern of the prism portions 3 and flat portion 4 in the first region, since the portion emitted to the outside is bright and the portion reflected inside is dark.

[0031] 3, the parts that look bright when viewed from the emission portion 2b are referred to as bright, and the parts that look dark are referred to as dark, with bright being shown as white and dark being shown as black. In the light and dark pattern of the light beam, the bright parts correspond to the parts that become the emitted light L3 emitted to the outside of the light guide 2, and the dark parts correspond to the parts that become the incident light L2 reflected inside the light guide 2. In the structural pattern, the bright parts correspond to the emission surface 3a of the prism portion 3, and the dark parts correspond to the flat portion 4.

[0032] Here, since the light reflected at the exit portion is reflected on the smooth surface and reaches the exit portion again and travels a certain distance, the light pattern of the light beam when it reaches the second region changes from the light pattern of the light beam in the first region. The light pattern of the light beam in the second region is bright in the portion of the second region where the light reflected at the first region reaches, and dark in the other portion. On the other hand, in the structure of the comparative example, the pitch intervals of the prism parts 3 in the exit portion are all the same, that is, the structural patterns of the prism parts 3 and the flat part 4 are the same in the first region and the second region. However, since the light pattern of the light beam in the second region changes from the light pattern of the light beam in the first region, it is slightly shifted from the structural pattern of the prism parts 3 and the flat part 4 in the second region. For this reason, in the structure of the comparative example, as shown in FIG. 3, moire occurs due to a slight shift between the light pattern of the light beam in the second region and the structural patterns of the prism parts 3 and the flat part 4. That is, in the structure of the comparative example, the periodic structure of the prism portions 3 and flat portions 4 is constant, whereas the light and dark pattern of the incident light changes as the light is guided inside the light guide, causing moire.

[0033] In contrast, the optical member 1 of this embodiment is designed such that the pitch interval P1 of the prism portions 3 in the first region 2ba is different from the pitch interval P2 of the prism portions 3 in the second region 2bb, and the change in the light and dark pattern of the incident light L2 is taken into consideration, thereby making it possible to reduce moire. Specifically, the optical member 1 is designed such that the pitch interval P2 of the prism portions 3 in the second region 2bb matches the light and dark pattern of the light beams in the second region 2bb after the change from the light and dark pattern of the light beams in the first region 2ba. In other words, the optical member 1 is configured such that the light and dark pattern of the light beams matches the structural patterns of the prism portions 3 and the flat portion 4 in the second region 2bb, thereby suppressing the occurrence of moire.

[0034] Specifically, the light reflected by the first region 2ba of the incident light L2 is referred to as the "specific reflected light" for the sake of convenience, and the amount of change in the pitch interval between the lights in the light guiding direction D2 when the specific reflected light reaches the second region 2bb is referred to as ΔP. ​​In other words, ΔP is the difference between the pitch interval between the lights when the specific reflected light is reflected by the first region 2ba and the pitch interval between the lights when the specific reflected light reaches the second region 2bb, that is, the amount of change in the pitch due to one round trip of the specific reflected light. In this case, the optical member 1 reduces moire by satisfying the following formula (2) or (3) between the region reflecting the specific reflected light in the emission section 2b and the adjacent region adjacent to the region where the specific reflected light reaches.

[0035] N × (P2 + ΔP) = P1 (2) (P2 + ΔP) = N × P1 (3) In equations (2) and (3), N is a positive integer.

[0036] Here, for example, as shown in FIG. 4 and FIG. 5, a viewer's viewpoint P1 is located on the side of the emission portion 2b and on which emitted light beams L3A and L3B from two prism portions 3 adjacent to each other at a pitch interval P2 in the second region bb are incident. Eand the distance between the prism portion 3 that emits the emitted light L3A is L. L is the distance along the emission direction of the emitted light L3A. The emitted light L3A is the emitted light L3 emitted from the prism portion 3 located at the center of the second region 2bb among the two prism portions 3 adjacent to each other in the second region 2bb. The emitted light L3B is the emitted light L3 emitted from the adjacent prism portion 3 that is adjacent to the prism portion 3 that emits the emitted light L3A in the second region 2bb in the opposite direction to the light guide direction D2. In addition, in FIG. 4 and FIG. 5, for ease of viewing, the emitted light L3A and the incident light L2A emitted as the emitted light L3A are shown by solid lines, and the incident light L2B emitted as the emitted light L3B and the incident light L2B are shown by dashed lines. In addition, in FIG. 5, the incident light L2C described later is shown by a dashed line.

[0037] For example, as shown in FIG. 5, if the exit angle of the exit light L3A is θ, then from the same viewpoint P E The emergent light L3B incident on the lens has an emergence angle different from that of the emergent light L3A. If the difference between the emergence angle of the emergent light L3B and that of the emergent light L3A is Δθ, then the emergence angle is θ+Δθ. This angle difference Δθ is expressed by the following formula (4). Furthermore, formula (4) can be approximated by formula (5).

[0038] Δθ=tan -1 (P2·cosθ / (L+P2·sinθ))···(4) Δθ≒P2·cosθ / (L+P2·sinθ)···(5) If the emitted light beams L3A and L3B are adjacent emitted light beams and the difference in the light guide angle of the adjacent emitted light beams in the light guide body 2, that is, the angle difference between the incident light beams L2A and L2B, is Δφ, then Δφ is expressed by equation (6).

[0039] Δφ=sin -1 (sin(π / 2-θ-ψ) / n)-sin -1 (sin(π / 2-θ-ψ-Δθ) / n)...(6) At this time, ΔP is the change in the pitch of the incident lights L2A, L2B at the position where they are reflected in the first region 2ba from the pitch interval P2 in the emission region of the second region 2bb, as shown in FIG. 5, and is expressed by the following equation (7).

[0040] ΔP=2T(1 / tan(sin -1 (sin(π / 2-θ-ψ-Δθ) / n)+ψ)-1 / tan(sin -1 (sin(π / 2-θ-ψ) / n)+ψ))···(7) Here, the incident light that is incident on the same prism portion 3 as the exit light L3B and has the same light guide angle φ as the incident light L2A is defined as the incident light L2C. At this time, since the incident lights L2A and L2C are parallel, the pitch of the incident lights L2A and L2C at the position where the incident lights L2A and L2C are reflected in the first region 2ba is P2. Also, as shown in FIG. 5, in the reflection region of the exit portion 2b where the pitch interval of the incident lights L2A and L2C is P2, the interval between the incident lights L2A and L2B in the light guide direction D2 is X. At this time, the interval X in the reflection region of the incident lights L2A and L2B is the pitch interval P2 of the incident lights L2A and L2C in the same region plus the pitch change amount ΔP. Then, when X satisfies the formula (8), the distance from the viewpoint P E When viewed from the front, the light and dark pattern of the light in the second region 2bb matches the structural pattern of the prism portion 3 and the flat portion 4, and these two patterns completely overlap, thereby minimizing the intensity of the moire.

[0041] X = P2 + ΔP = P1 (8) Furthermore, the overlap between the light and dark pattern of the light beam and the structural pattern of the prism portion 3 and the flat portion 4 is valid even if it is N times larger, where N is a positive integer. Therefore, when formula (2) or (3) is satisfied, no moire occurs.

[0042] In this way, the optical member 1 is designed such that the pitch interval P2 of the prism portions 3 in the second region 2bb is smaller than the pitch interval P1 of the prism portions 3 in the first region 2ba in accordance with the change in the light and dark pattern of the incident light L2. EThe light and dark pattern of the light rays when viewed from the outside coincides with the structural pattern of the emission section 2b, and the occurrence of moire that occurs when periodic patterns with slightly different periods overlap each other is suppressed.

[0043] According to this embodiment, the light guide 2 is designed to reflect the incident light L2 by total reflection at the flat portion 4 and the smooth surface 2c of the exit portion 2b, resulting in an optical member 1 with a half-mirrorless structure. The light guide 2 also has a configuration in which the exit portion 2b has a plurality of regions 2ba-2bc with different pitch intervals at a predetermined width, and the pitch intervals P1, P2 satisfy a predetermined relationship in accordance with the change in the light and dark pattern of the incident light L2 in one round trip due to reflection between the exit portion 2b and the smooth surface 2c. As a result, the viewpoint P E Since there is no misalignment between the light and dark pattern of the light rays when viewed from the outside and the structural pattern of the emission part 2b, it is possible to suppress the occurrence of moire, resulting in an optical member 1 with reduced moire while having a half-mirrorless structure.

[0044] Although an example in which emission section 2b is configured with three regions has been described above, this is not limiting, and emission section 2b may be configured with four or more regions with different pitch intervals of prism portions 3. In this case, except for the region configured only with a plurality of prism portions 3, the difference in pitch interval between two adjacent regions in light guiding direction D2 is designed to satisfy formula (2) or formula (3), thereby making it possible to suppress the occurrence of moire in the second and subsequent regions.

[0045] Second embodiment The optical member 1 of the second embodiment will be described with reference to the drawings.

[0046] 6, the optical member 1 of this embodiment differs from that of the first embodiment in that a plurality of reflective layers 5 are formed inside the light guide 2. This embodiment will mainly describe this difference.

[0047] In this embodiment, the light guide 2 has multiple reflective layers 5 formed along the light guide direction D2, and is configured so that the incident light L2 is reflected by the multiple reflective layers 5 instead of the flat portion 4, as shown in Figure 7, for example.

[0048] The multiple reflective layers 5 are formed in the light guide 2 at a predetermined interval from each other along the light guide direction D2. The multiple reflective layers 5 are arranged, for example, between the incident surface 2a and the smooth surface 2c and the exit portion 2b, at positions corresponding to the first region 2ba and the second region 2bb. For example, the surface of the multiple reflective layers 5 on the smooth surface 2c side is a reflective surface 5a that reflects a part of the incident light L2, and the reflective surface 5a is approximately parallel to the smooth surface 2c. The term "approximately parallel" includes not only a case where the layers are completely parallel, but also a case where the layers are almost parallel, although there is an unavoidable slight difference due to processing errors, etc. As shown in FIG. 6, for example, the multiple reflective layers 5 are not arranged in the third region 2bc or in the vicinity thereof so as not to interfere with the incident light L2 entering the third region 2bc while the respective reflective surfaces 5a are located on the same plane. The multiple reflective layers 5 are arranged, for example, in the first region 2ba and the second region 2bb, so as to avoid being on a virtual straight line that passes through the exit surface 3a and has an angle of φ with respect to the thickness direction D1, so as not to prevent the incident light L2 with a light guide angle φ from entering the exit surface 3a of the prism section 3.

[0049] The multiple reflective layers 5 are arranged in the first region 2ba at a pitch P31 that is substantially the same as the pitch interval P1 of the prism portions 3 in the first region 2ba, and in the second region 2bb at a pitch P32 that is substantially the same as the pitch interval P2 of the prism portions 3 in the second region 2bb. In other words, the light guide 2 is configured to have multiple reflective regions with different pitch intervals in the light guide direction D2 of the reflective layers 5. The multiple reflective layers 5 are arranged in the vicinity of the exit portion 2b. Specifically, the distance between the reflective surface 5a and the smooth surface 2c in the thickness direction D1 is Tr, and the multiple reflective layers 5 are formed at positions where the difference between the distance between the smooth surface 2c and the flat portion 4 in the thickness direction D1, that is, T corresponding to the thickness of the light guide, and Tr is sufficiently smaller than T. In other words, the multiple reflective layers 5 are formed at positions where T≫(T-Tr) is established.

[0050] The reflective layers 5 are, for example, hollow layers filled with air, or made of a reflective material different from the material constituting the light guide 2, or made of a dielectric multilayer film. 1 is greater than 1, the reflective layer 5 may be a hollow layer filled with air having a refractive index of 1. In this case, the incident light L2 having a light guide angle φ incident on the reflective layer 5 is expressed as sinφ>1 / n 1 Since the condition is satisfied, the light is reflected toward the smooth surface 2c by total reflection. Examples of the reflective material include, but are not limited to, metal materials having a visible light reflectance of a predetermined value or more, such as silver, aluminum, and chromium. The reflective layer 5 may be made of any material that reflects visible light, such as TiO 2 and SiO 2 Alternatively, the dielectric layer 12 may be formed of a known dielectric multilayer film in which relatively high refractive index materials and low refractive index materials such as those mentioned above are repeatedly laminated alternately.

[0051] In the optical member 1 of this embodiment, the pitch interval of the reflective layers 5 in the first region 2ba is P31, and the pitch interval of the reflective layers 5 in the second region 2bb is P32, satisfying the following formula (9) or (10).

[0052] N × (P32 + ΔPr) = P31 (9) (P32 + ΔPr) = N × P31 (10) In formulas (9) and (10), N is a positive integer. ΔPr is the amount of change in the pitch interval between light beams in the light guiding direction D2 when the light reflected by the reflective layer 5 in the first region 2ba is treated as specific reflected light, and the specific reflected light makes one round trip due to internal reflection in the light guide 2 and reaches the second region 2bb. When P31=P1 and P32=P2, ΔPr corresponds to ΔP in the first embodiment. In addition, at this time, formulas (9) and (10) correspond to formulas (2) and (3) in the first embodiment, respectively, and the optical member 1 of this embodiment is designed to satisfy the above formulas (4) and (7). As a result, the user's viewpoint P located at the emission section 2b EWhen viewed from the outside, the light and dark pattern of the light beams in the second region 2bb matches the structural pattern, thereby reducing the occurrence of moire.

[0053] The light guide 2 can be obtained, for example, by forming the upper half of the light guide 2 on the smooth surface 2c side of the plurality of reflective layers 5 in the thickness direction D1 by a known resin molding method using a mold (not shown), and then changing the mold (not shown) to form the remaining lower half by a known resin molding method. When the reflective layer 5 is a hollow layer, the light guide 2 can be obtained by forming a recess in one of the above-mentioned two-stage resin molding process, and forming a cavity filled with air while leaving the recess in the other process. When the reflective layer 5 is a metal reflective film made of a reflective material such as a metal material, or a known dielectric multilayer film, the light guide 2 can be obtained by sandwiching a film formation process of the reflective layer 5, such as sputtering or CVD, between the above-mentioned two-stage resin molding process.

[0054] The optical member 1 of this embodiment also provides the same effects as those of the first embodiment.

[0055] (Modification of the second embodiment) In the optical member 1, the light guide 2 may be composed of a plurality of members, not a single member, as shown in FIG. 8. For example, the light guide 2 may be composed of a light guide section 21 having a plurality of reflective layers 5 and constituting a smooth surface 2c and an inclined surface 2d, a prism sheet 23 constituting the exit section 2b and having a plurality of prism sections 3, and a transparent layer 22 connecting the light guide section 21 and the prism sheet 23. In this case, the light guide section 21, the transparent layer 22, and the prism sheet 23 are all made of light-transmitting materials, and the refractive indexes are adjusted so that total reflection does not occur at the interfaces between them. This makes it easier to manufacture the light guide 2 than when it is composed of a single member.

[0056] According to the above-described first modification, the optical member 1 has the same effect as the above-described second embodiment, and further has the effect of being easier to manufacture.

[0057] In addition, as shown in FIG. 9, the optical member 1 may have a configuration in which the emission portion 2b does not have a flat portion 4 and is composed of only the prism portion 3. In this case, the width of the adjacent surface 3b of the prism portion 3 in the light guide direction D2 is larger than that of the emission surface 3a, and the pitch interval is Pp and the pitch interval of the reflective layer 5 is Pr, where Pp is approximately the same as Pr. The pitch interval Pp is P1 in the first region 2ba and P2 in the second region 2bb. In addition, when the emission portion 2b is composed of only the prism portion 3, a light-shielding film (not shown) may be formed on the adjacent surface 3b. This can prevent external light from the emission portion 2b side from entering the light guide body 2, and external light from the emission portion 2b side that is not intended is not superimposed on the emitted light L3, and an effect of suppressing noise is also obtained. The light-shielding film may be, for example, a light-absorbing film that absorbs visible light or a light-scattering film that scatters visible light, and may be formed by coating or surface roughening.

[0058] The second modified example described above also provides the optical member 1 with the same effects as those of the second embodiment. In addition, when a light-shielding film (not shown) is formed on the adjacent surface 3b of the prism portion 3, a noise suppression effect can also be obtained.

[0059] Third embodiment The optical member 1 of the third embodiment will be described with reference to the drawings.

[0060] 10, the optical member 1 of this embodiment differs from that of the first embodiment in that the configuration of the light guide 2 is changed. In this embodiment, this difference will be mainly described.

[0061] 10, the "thickness direction D1" in this embodiment is a direction along a normal direction to a plurality of second flat portions 9, which correspond to the smooth surface 2c in each of the above embodiments, as described below. The "light guiding direction D2" in this embodiment is a direction perpendicular to the thickness direction D1, and is a direction from an incident side surface 2i, which will be described later, toward a terminal surface 2e.

[0062] In this embodiment, the light guide 2 includes an incident surface 2a and a reflecting surface 2g adjacent to each other, a reflecting-exiting surface 2f disposed opposite the incident surface 2a, and a smooth exiting surface 2h disposed opposite the reflecting surface 2g and adjacent to the reflecting-exiting surface 2f. In this embodiment, the light guide 2 includes an incident side surface 2i connecting the incident surface 2a and the reflecting-exiting surface 2f, and a terminal surface 2e on the opposite side of the incident side surface 2i connecting the reflecting surface 2g and the smooth exiting surface 2h. As shown in FIG. 11, for example, the light guide 2 emits a part of the incident light L2 from the incident surface 2a to the outside from the reflecting-exiting surface 2f, and reflects the remaining part internally toward the reflecting surface 2g, and reflects this reflected light in two different directions by the reflecting surface 2g. The light guide 2 is configured so that light reflected by a second prism portion 8 of the reflecting surface 2g, which will be described later, is emitted to the outside from the smooth exit surface 2h, and light reflected by the second flat portion 9 is internally reflected by the smooth exit surface 2h to be guided. This will be described in detail later.

[0063] In this embodiment, the incident surface 2a is not adjacent to the reflection-emitting surface 2f corresponding to the emission portion 2b in the first embodiment, but is arranged to face the first flat portion 7 of the reflection-emitting surface 2f so as to be approximately parallel. The term "approximately parallel" includes the case where the incident surface 2a is almost parallel with a slight deviation due to unavoidable factors such as processing errors, in addition to the case where the incident surface 2a is completely parallel. The incident surface 2a is adjacent to the reflection surface 2g corresponding to the smooth surface 2c in the first embodiment, and is located on the same plane as the multiple second flat portions 9 of the reflection surface 2g. The incident surface 2a is adjacent to the incident side surface 2i on the side opposite to the reflection surface 2g. As in each of the above embodiments, the incident surface 2a is in a state where it protrudes from the other member 100 to which the optical member 1 is attached, and allows the outside scene light L1 to enter the inside of the light guide 2. In this embodiment, the incident surface 2a is located at a position where a portion of the incident light L2 reflected by the reflective exit surface 2f is incident at an angle greater than or equal to the critical angle, and therefore the incident surface 2a also functions as a light guiding surface that reflects this portion of the incident light L2 toward the smooth exit surface 2h by total reflection.

[0064] The incident side surface 2i is, for example, a single flat surface that intersects with the incident surface 2a and the reflection / exit surface 2f and connects these surfaces.

[0065] The reflective emission surface 2f is the surface where the incident light L2 from the incident surface 2a first reaches, and has a plurality of first prism portions 6 and a plurality of first flat portions 7. The reflective emission surface 2f is configured, for example, such that the first prism portions 6 and the first flat portions 7 are alternately and repeatedly arranged along the light guiding direction D2. The reflective emission surface 2f is adjacent to the smooth emission surface 2h on the side opposite to the incident side surface 2i, and the plurality of first flat portions 7 are located on the same plane as the smooth emission surface 2h.

[0066] The reflection exit surface 2f has, for example, a first reflection area 2fa and a second reflection area 2fb, with the smooth exit surface 2h side being the first reflection area 2fa and the incident side surface 2i side being the second reflection area 2fb. The first reflection area 2fa and the second reflection area 2fb are both prism arrays in which the first prism portions 6 and the first flat portions 7 are alternately arranged. The first reflection area 2fa is an area that reflects the incident light L2 from the incident surface 2a to the reflection surface 2g. The second reflection area 2fb is an area that reflects the incident light L2 to the incident surface 2a, as shown in FIG. 11, for example. That is, the light guide 2 is configured such that the incident light L2 reflected by the first reflection area 2fa reaches the reflection surface 2g directly, and the incident light L2 reflected by the second reflection area 2fb reaches the reflection surface 2g via the incident surface 2a. The width of the reflective emission surface 2f in the light guide direction D2 is W, and the distance between the second flat portion 9 and the smooth emission surface 2h in the thickness direction D1 is T, where W is expressed by equation (11).

[0067] W = 2T tan(sin -1 (sin(θ) / n)+π-2ψ) (11) In addition, when it is desired to reduce the height T corresponding to the thickness of the light guide body 2 and to make it thinner, the light guide angle φ 1 is 70° or more, i.e., φ 1 It is preferable to design so that +2ψ≧70 is satisfied.

[0068] The first prism portions 6 are recesses extending from the plane of the first flat portions 7 toward the inside of the light guide 2. As shown in Fig. 10, the first prism portions 6 are groove-shaped in cross section, each having two intersecting wall surfaces that face each other, one of which is a first reflecting portion 6a and the other is a connecting surface 6b. The first prism portions 6 have a pitch interval of P1 in both the first reflecting region 2fa and the second reflecting region 2fb.

[0069] The first reflecting portion 6a is, for example, a single flat surface, and is one of the two wall surfaces of the first prism portion 6 whose normal direction faces the reflecting surface 2g. In other words, the first reflecting portion 6a is an inclined surface inclined at an inclination angle ψ with respect to the thickness direction D1 so as to face the reflecting surface 2g with respect to the incident surface 2a. The first reflecting portion 6a is a portion that functions as a first reflecting surface that reflects the incident light L2 from the incident surface 2a toward the reflecting surface 2g by total reflection, as shown in FIG. 11, for example. In other words, the first reflecting portion 6a is a portion that corresponds to the flat portion 4 in the first embodiment. The connecting surface 6b is a surface that connects the first reflecting portion 6a and the first flat portion 7 among the two wall surfaces of the first prism portion 6, and is, for example, a single flat surface.

[0070] The first flat portions 7 are smooth surfaces arranged opposite and substantially parallel to the incident surface 2a, as shown in Fig. 11, and the incident light L2 from the incident surface 2a is incident at an angle less than the critical angle. The incident light L2 incident on the first flat portions 7 is emitted to the outside. In other words, the first flat portions 7 are portions corresponding to the emission surface 3a in the first embodiment.

[0071] The reflecting surface 2g is a surface adjacent to the incident surface 2a, and is a portion that reflects the reflected light from the reflecting and emitting surface 2f. The reflecting surface 2g has a plurality of second prism portions 8 and a second flat portion 9, and for example, a part of the reflecting surface 2g is a prism array in which the second prism portions 8 and the second flat portions 9 are alternately arranged along the light guide direction D2. The reflecting surface 2g has a plurality of first reflecting portions 6a as a first reflecting surface, a second reflecting surface that forms a pair with the first reflecting surface, and a second prism portion 8 and a second flat portion 9 that correspond to a third reflecting surface. When the optical member 1 is attached to another member 100 by a mounting jig or the like (not shown), as shown in FIG. 11, for example, the reflecting surface 2g faces the other member 100 with a predetermined gap therebetween.

[0072] The reflecting surface 2g has, for example, a first region 2ga and a second region 2gb in which the pitch intervals of the second prism portions 8 are different. The first region 2ga is a region in which the second prism portions 8 and the second flat portions 9 are alternately and repeatedly arranged, and reflects the incident light L2 in two directions. The second region 2gb is a region composed only of a plurality of second prism portions 8, and reflects the incident light L2 in one direction.

[0073] The first region 2ga has a first entrance region 2ga1 and a second entrance region 2ga2, with the first entrance region 2ga1 on the entrance surface 2a side and the second entrance region 2ga2 on the second region 2gb side. Both the first entrance region 2ga1 and the second entrance region 2ga2 are prism arrays in which the second prism portions 8 and the second flat portions 9 are alternately arranged, but the pitch interval P2 of the second prism portions 8 is different. The first entrance region 2ga1 is an area where the reflected light from the first reflection region 2fa is directly incident, as shown in FIG. 11, for example, and the incident light L2 reflected once by the first reflection region 2fa reaches the first entrance region 2ga1. The second entrance region 2ga2 is an area where the reflected light from the second reflection region 2fb is incident and is reflected at least once by the entrance surface 2a, and the incident light L2 reflected three times by the second reflection region 2fb, the entrance surface 2a, and the smooth exit surface 2h reaches the second entrance region 2ga2.

[0074] The second prism portions 8 are projections that protrude outward from the plane formed by the second flat portions 9, and are, for example, triangular in cross section. The second prism portions 8 face each other and have two intersecting surfaces, one of which is a second reflecting portion 8a that reflects light reflected by the first reflecting portion 6a, and the other is an adjacent surface 8b.

[0075] The second reflecting portions 8a are, for example, flat surfaces parallel to the first reflecting portion 6a and inclined at an inclination angle ψ with respect to the thickness direction D1. As shown in FIG. 11, the second reflecting portions 8a reflect a part of the reflected light at the first reflecting portion 6a to the smooth emission surface 2h by total reflection. The second reflecting portions 8a reflect the reflected light at the first reflecting portion 6a in a direction toward the smooth emission surface 2h, different from the direction of the reflected light at the second flat portion 9. The light reflected at the second reflecting portions 8a is incident on the smooth emission surface 2h at a light guide angle less than the critical angle, and is emitted from the smooth emission surface 2h to the outside. In other words, the second reflecting portion 8a is a reflecting surface used to emit the light reflected at the first reflecting portion 6a from the smooth emission surface 2h, and functions as a so-called "emission reflection surface." For this reason, the incident light incident on second region 2gb formed only of a plurality of second prism portions 8 is reflected by second reflecting portion 8a, and almost all of the incident light is emitted to the outside from smooth emission surface 2h.

[0076] The second flat portions 9 are, for example, located on the same plane as the incident surface 2a, and are portions that reflect the light reflected by the first reflecting portion 6a by total reflection toward the smooth emission surface 2h side, in a direction different from the direction of the light reflected by the first reflecting portion 6a. The second flat portions 9 are, for example, parallel to the smooth emission surface 2h. As a result, the light reflected by the second flat portions 9 is incident on the smooth emission surface 2h at a light guide angle equal to or greater than the critical angle, and is totally reflected by the smooth emission surface 2h. In other words, the second flat portions 9 are a reflection surface for guiding the light reflected by the first reflecting portion 6a inside the light guide 2, and function as a so-called "light guide reflection surface."

[0077] The smooth emission surface 2h is disposed continuously with the reflective emission surface 2f and is a smooth surface parallel to the incident surface 2a and the second flat portion 9. The smooth emission surface 2h is disposed opposite the reflecting surface 2g, and receives, for example, incident light L2 from the incident surface 2a, light internally reflected by the incident surface 2a, and light internally reflected by the reflecting surface 2g. The smooth emission surface 2h reflects the reflected light from the second flat portion 9 toward the reflecting surface 2g, and emits the reflected light from the second reflecting portion 8a to the outside.

[0078] The terminal surface 2e is located at the end in the light guiding direction D2, and in this embodiment, it is a side surface that connects the reflecting surface 2g and the smooth exit surface 2h. The light that reaches the terminal surface 2e of the incident light L2 is, for example, emitted to the outside, but it does not have to be emitted to the outside by covering the terminal surface 2e with a light absorbing film (not shown).

[0079] The above is the basic configuration of the light guide 2 in this embodiment. [Light Guidance and Moire Reduction in Optical Components] Next, light guidance at the reflective exit surface 2f, the reflective surface 2g, and the smooth exit surface 2h will be described.

[0080] In this embodiment, the light guide 2 has a half-mirrorless structure designed so that the incident light L2 is totally reflected by the first reflecting portion 6a, the second reflecting portion 8a of the reflecting surface 2g, and the second flat portion 9, and the light reflected by the second flat portion 9 is totally reflected by the smooth exit surface 2h, and guided inside. For example, as shown in FIG. 12, the incident angle of the light that is incident on the first flat portion 7 out of the incident light L2 is set to φ 0 A part of the incident light L2 is reflected by the first reflecting portion 6a inclined at an inclination angle ψ with a reflectance of φ 0 The incident angle is +ψ. The incident angle is φ 0 is less than the critical angle for the first flat portion 7. Therefore, the incident light L2 that is incident on the first flat portion 7 is emitted to the outside at an angle θ. 0The incident angle of +ψ is the angle between the direction of the incident light L2 incident on the first reflecting portion 6a and the normal direction N1, where N1 is the normal direction to the surface of the first reflecting portion 6a. In this case, when the refractive index of the light guide 2 is n and the external medium is air with a refractive index of 1, the first reflecting portion 6a satisfies the condition for total reflection of the following formula (12).

[0081] sin(φ 0 +ψ)>1 / n (12) The incident light L2 reflected by the first reflecting portion 6a is reflected at the same angle as the incident angle, so the angle with respect to the thickness direction D1, i.e., the light guide angle, is set to φ 1 As a result, φ 1 =φ 0 Of the incident light L2 reflected by the first reflecting portion 6a, the light incident on the incident surface 2a is incident at an angle φ as shown in FIG. 1 Since the light guide 2 satisfies the formula (12), the angle is greater than the critical angle, and the light is reflected by the smooth exit surface 2h due to total reflection. Furthermore, the light L2 reflected by the first reflecting portion 6a that is incident on the second flat portion 9 has a light guide angle φ greater than the critical angle, as shown in FIG. 1 Since the light is incident on the incident surface 2a, it is reflected by the smooth exit surface 2h due to total reflection, similar to the incident surface 2a. Furthermore, the light reflected on the incident surface 2a and the light reflected on the second flat portion 9 are both reflected by the light guide angle φ 1 Since the light is incident on the smooth exit surface 2h at 200° C., it is reflected by total reflection towards the reflecting surface 2g.

[0082] On the other hand, the light L2 reflected by the first reflecting portion 6a that enters the second reflecting portion 8a is incident at an angle δ with respect to the normal direction N1 to the second reflecting portion 8a. In this case, when the refractive index of the light guide 2 is n and the external medium is air with a refractive index of 1, the second reflecting portion 8a satisfies the condition for total reflection of the following formula (13).

[0083] sinδ>1 / n (13) The second reflecting portion 8a is parallel to the first reflecting portion 6a, i.e., has an inclination of ψ with respect to the thickness direction D1, and reflects the incident light L2 incident at an angle δ at an incident angle φ 0The light reflected by the second reflecting portion 8a is reflected at an incident angle φ that is less than the critical angle. 0 Since the light reaches the smooth exit surface 2h at an angle θ, it is emitted to the outside. Note that the angle δ is φ 1 +ψ-π / 2.

[0084] In this embodiment, the light and dark pattern of the light reflected by the reflective exit surface 2f changes when it reaches the first region 2ga of the reflective surface 2g. Therefore, if the pitch interval P2 of the second prism portions 8 in the first region 2ga is the same as the pitch interval P1 of the first prism portions 6 on the reflective exit surface 2f, moire will occur due to the misalignment of the patterns. Therefore, in order to suppress moire, the light guide 2 is designed to satisfy the following formula (14).

[0085] P2 + ΔP = P1 (14) In this embodiment, the light of the incident light L2 reflected by the reflective exit surface 2f is defined as specific reflected light, and ΔP is the amount of change in the pitch spacing between the lights in the light guide direction D2 when the specific reflected light reaches the reflective surface, and is expressed by equation (15).

[0086] ΔP=mT(tan(sin -1 (sin(θ+Δθ) / n)+π-2ψ)-tan(sin -1 (sin(θ) / n)+π-2ψ)) (15) In formula (15), m is the number of reflections of the incident light L2 that reaches the reflecting surface 2g inside the light guide 2, and is either 1 or 3. When m=1 in formula (15), ΔP corresponds to the region where the incident light L2 is reflected once inside, that is, the first incident region 2ga1. When m=3 in formula (15), ΔP corresponds to the region where the incident light L2 is reflected three times inside, that is, the second incident region 2ga2. That is, in the first region 2ga, the pitch interval P2 between the first incident region 2ga1 and the second incident region 2ga2 differs depending on the number of reflections of the incident light L2 that reaches it inside the light guide 2.

[0087] Δθ in formula (15) is the angular difference between two outgoing lights L3 that are reflected by the second reflecting parts 8a of two adjacent second prism parts 8 in the first region 2ga and are emitted from the smooth emission surface 2h, and reach the eye of the viewer on the smooth emission surface 2h side. Of the two outgoing lights L3 emitted from the smooth emission surface 2h described above, the one on the terminal surface 2e side corresponds to the reference light ray described in the first embodiment. In addition, the second prism part 8 that is adjacent to the second prism part 8 that reflects the incident light L2 that is the reference light ray in the opposite direction to the light guide direction D2 is the adjacent second prism part. In other words, Δθ corresponds to the angular difference between the light that reaches the viewer's eye among the outgoing lights L3 that are reflected by the adjacent second prism part and are emitted from the smooth emission surface 2h, and the reference light ray. For this reason, Δθ is expressed by formula (4) as in the first embodiment, and is approximated to formula (5). By satisfying formula (15), the light guide 2 ensures that the pattern spacing of the incident light L2 that is reflected by the reflective exit surface 2f and reaches the first region 2ga directly or via the entrance surface 2a and the smooth exit surface 2h matches the pattern spacing of the second prism portion 8. For this reason, the light guide 2 has a half-mirrorless structure and is configured to reduce moire.

[0088] The optical member 1 of this embodiment also provides the same effects as those of the first embodiment.

[0089] (Modification of the third embodiment) In the third embodiment, an example in which the first prism portion 6 is a V-shaped groove and the second prism portion 8 is a protrusion has been described, but the present invention is not limited to this. For example, as shown in Fig. 14, the optical member 1 may have the first prism portion 6 as a protrusion protruding from the first flat portion 7 and the second prism portion 8 as a V-shaped groove recessed inward from the second flat portion 9.

[0090] In the above third embodiment, the pitch interval of the first prism portion 6 is the first prism pitch, the pitch interval of the second prism portion 8 is the second prism pitch, and the first prism pitch P1 is the same in the first reflection area 2fa and the second reflection area 2fb. Then, an example has been described in which the second prism pitch P2 on the reflection surface 2g is made small so as to satisfy formula (15).

[0091] However, without being limited thereto, the second prism pitch P2 may be the same in the first entrance region 2ga1 and the second entrance region 2ga2, and the first prism pitch P1 may be different in the first reflection region 2fa and the second reflection region 2fb. Even when the pitch interval P2 is fixed and the pitch interval P1 side is different for the regions 2ga1 and 2ga2, the occurrence of moire can be suppressed by satisfying formula (15).

[0092] These modified examples also provide the optical member 1 that can achieve the same effects as the third embodiment.

[0093] (Other embodiments) 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, more than one, or less than one, are also within the scope and concept of the present disclosure.

[0094] In each of the above embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential, except when it is specifically stated that they are 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 it is specifically stated that they are 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 it is specifically stated that they are essential or when it is clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0095] 2...Light guide, 2a...Incidence surface, 2b...Emission part, 2c...Smooth surface, 2d...Slanted surface, 2e...Terminal surface 2ba~2bc...1st~3rd area (of the injection part), 2f...reflective emission surface 2fa...first incident area (of the reflective exit surface), 2fb...second incident area (of the reflective exit surface) 2g...reflection surface, 2ga...first area (of the reflection surface), 2ga1...first reflection area 2ga2...second reflective area, 2gb...second area (of reflective surface), 2h...smooth exit surface 2i...Connection surface, 3...Prism part, 3a...Emission surface, 4...Flat part, 5...Reflection layer 6... (reflection and emission surface) first prism portion, 6a... (reflection portion) (of the first prism portion) 7...first flat portion (of the reflection exit surface), 8...second prism portion (of the reflection surface) 8a...reflection portion (of the second prism portion), 9...second flat portion (of the reflection surface), D1...thickness direction D2...Light guiding direction, L1...Outside light, L2...Incoming light, L3...Outgoing light

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 scene light is incident, an exit portion (2b) having a plurality of protruding prism portions (3) and extending in a direction intersecting the incident surface, a smooth surface (2c) facing the exit portion, reflection surfaces (4, 5) facing the smooth surface, and a terminal surface (2e) located on the opposite side to the incident surface and connecting the exit portion and the smooth surface, and is made of a light-transmitting material; The smooth surface reflects a part of the incident light (L2) from the incident surface toward the exit portion by total reflection, The emission section has a plurality of regions (2ba, 2bb, 2bc) in which the prism portions are repeatedly arranged, The plurality of regions have different pitch intervals of the prism portions, an optical component in which a direction along one plane of the smooth surface, from the incident surface toward the terminal surface, is a light guiding direction (D2), a pitch interval between two adjacent prism portions in one of the plurality of regions is P1, another region adjacent to the one region along the light guiding direction is an adjacent region, a pitch interval between two adjacent prism portions in the adjacent region is P2, light of the incident light reflected at the region having a pitch interval of P1 is a specific reflected light, and an amount of change in the pitch interval of the specific reflected light in the light guiding direction when the specific reflected light reaches the adjacent region is ΔP, and the light guiding body satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer.

2. The direction along the normal direction to the smooth surface is defined as a thickness direction (D1), The distance between the emission portion and the smooth surface in the thickness direction is T, An incident angle between the direction in which the external light incident on the incident surface travels and the thickness direction is defined as θ; The inclination angle of the incident surface with respect to the thickness direction is defined as ψ, The light (L3) emitted to the outside from one of the prism portions in the adjacent region and incident on the eye of a viewer positioned on the side of the emission portion is defined as a reference light ray, Among the plurality of prism portions constituting the adjacent region, a prism portion adjacent to one of the prism portions that emits the reference light beam in a direction opposite to the light guiding direction is defined as an adjacent prism portion, An angular difference between the light that is emitted to the outside from the adjacent prism portion and that is incident on the viewer's eye and the reference light ray is defined as Δθ; The refractive index of the light-transmitting material is n, 2. The optical element according to claim 1, wherein the light guide satisfies the following formulas (1) and (2), where L is a distance between the prism portion that emits the reference light ray and the viewer's eye in the emission direction of the reference light ray. ΔP=2T(1 / ttan(sin －１ (sin(π / 2-θ-ψ-Δθ) / .)+ψ)-1 / tan(sin －１ (sin(π / 2-θ-ψ) / .)+ψ))・・・(1) Δθ=tan －１ (P2・cosθ / (L+P2・sinθ))・・・(2)

3. 2. The optical element according to claim 1, wherein the reflecting surface is a plurality of flat portions arranged alternately with parts of the plurality of prism portions, and reflects a part of the incident light toward the smooth surface by total reflection.

4. 2. The optical element according to claim 1, wherein the reflective surface is a surface facing the smooth surface among a plurality of reflective layers (5) arranged repeatedly and spaced apart from one another along the light guiding direction, the reflective surface being disposed inside the light guiding body between the emission portion and the smooth surface.

5. The optical member according to claim 1 , wherein an exit surface (3a) of the plurality of prism portions that emits a portion of the incident light to the outside is parallel to the entrance surface.

6. 2. The optical member according to claim 1, wherein the light guide satisfies sinφ>1 / n, where n is a refractive index of the light-transmitting material and φ is an incident angle of the light incident on the reflective surface and the smooth surface.

7. 2. The optical element of claim 1, wherein the direction along the normal direction to the smooth surface is a thickness direction (D1), the inclination angle of the incident surface with respect to the thickness direction is ψ, and the incident angle of the incident light with respect to the reflecting surface and the smooth surface is φ, and the light guide satisfies ψ<φ.

8. The light guide has an inclined surface (2d) connecting the incident surface and the smooth surface, A direction normal to the smooth surface is defined as a thickness direction (D1), a height of the incident surface in the thickness direction is defined as Td, and a distance between the emission portion and the smooth surface in the thickness direction is defined as Ts, and the light guide satisfies Td>Ts, The optical member according to claim 1 , wherein an incident angle of the incident light with respect to the reflecting surface and the smooth surface is φ, and an inclination angle of the inclined surface with respect to the thickness direction is ξ, and the inclined surface satisfies ξ<φ.

9. The optical member according to claim 3 , wherein the pitch interval of the prism portions in the plurality of regions decreases toward the end face.

10. the plurality of reflective layers each have a plurality of reflective regions having different pitch intervals of the reflective layers in the light guiding direction; The optical member according to claim 4 , wherein the pitch of the reflective layers in the plurality of reflective regions decreases toward the end face.

11. The optical member according to claim 4 , wherein the plurality of reflective layers are any one of an air layer, a metal reflective film, and a dielectric multilayer film.

12. An optical member that internally reflects and guides external light, a reflection surface (2g) disposed adjacent to the entrance surface and reflecting light from the reflection surface; a smooth emission surface (2h) disposed adjacent to the reflection surface and disposed opposite the reflection surface, reflecting a portion of the light reflected by the reflection surface of the incident light and emitting the remainder to the outside; an entrance side surface (2i) connecting the entrance surface and the reflection surface; and a terminal surface (2e) located on the opposite side of the entrance side surface and connecting the reflection surface and the smooth emission surface; the reflection exit surface is formed by alternately and repeatedly arranging a plurality of first prism portions (6) each having a first reflecting portion (6 a) that reflects the incident light toward the reflection surface and is inclined with respect to the incident surface, and a plurality of first flat portions (7) that are flat surfaces; the reflecting surface includes a plurality of second prism portions (8) having second reflecting portions (8a) that reflect a portion of the light reflected by the reflecting and emitting surface toward the smooth emitting surface, and a plurality of second flat portions (9) that are flat surfaces that reflect the remaining portion of the reflected light by total reflection; an optical component in which a direction along the incident surface from the incident side surface toward the terminal surface is a light guide direction (D2), a pitch interval in the light guide direction of two adjacent first prism portions is P1, a pitch interval in the light guide direction of two second prism portions into which reflected light from two first prism portions of the reflective surface having a pitch interval of P1 is incident is P2, light of the incident light that is reflected at the reflective exit surface is a specific reflected light, and an amount of change in the pitch interval of light in the light guide direction when the specific reflected light reaches the reflective surface is ΔP, and the light guide satisfies N×(P2+ΔP)=P1 or (P2+ΔP)=N×P1, where N is a positive integer.

13. The direction along the normal direction to the incident surface is defined as a thickness direction (D1), a distance between the incident surface and the first flat portion in the thickness direction is T; An incident angle between the direction in which the external light incident on the incident surface travels and the thickness direction is defined as θ; a tilt angle of the first reflecting portion with respect to the thickness direction is defined as ψ, The light (L3) emitted from the smooth exit surface to the outside is incident on the eye of a viewer positioned on the side of the smooth exit surface, and the reference light ray is a light beam; a second prism portion adjacent to one of the second prism portions that reflects the light that becomes the reference light ray in a direction opposite to the light guiding direction among the plurality of second prism portions that configure the reflecting surface is defined as an adjacent second prism portion, an angular difference between the reference light ray and a light incident on the viewer's eye among the emitted light that is reflected by the adjacent second prism portion and then emitted to the outside from the smooth emission surface, and the reference light ray is defined as Δθ; The refractive index of the light-transmitting material is n, 13. The optical element according to claim 12, wherein the light guide satisfies the following formulas (3) and (4), where L is a distance between a portion of the smooth emission surface from which the reference light ray is emitted and an eye of the viewer in the emission direction of the reference light ray. ΔP=mT(tan(sin －１ (sin(θ+Δθ) / n)+π-2ψ)-tan(sin －１ (sin(θ) / n)+π-2ψ))、(mは1または3)・・・(3) Δθ=tan －１ (P2・cosθ / (L+P2・sinθ))・・・(4)

14. The optical member according to claim 12 , wherein the first flat portion and the smooth exit surface are parallel to the entrance surface.

15. The optical member according to claim 12 , wherein the first reflecting portion is parallel to the second reflecting portion.

16. The optical member according to claim 12 , wherein the light guide satisfies sin φ>1 / n, where n is a refractive index of the light-transmitting material and φ is an incident angle of the incident light with respect to the first flat portion and the second flat portion.

17. The optical member according to claim 12 , wherein the light guiding body satisfies sin δ>1 / n, where n is a refractive index of the light-transmitting material and δ is an incident angle of the incident light with respect to the first reflecting portion and the second reflecting portion.

18. a pitch interval of the first prism portions in the light guiding direction is constant, the reflecting surface has a plurality of regions (2ga, 2gb) having different second prism pitches, which are pitch intervals of the second prism portions in the light guiding direction, The second prism pitch in each of the plurality of regions is fixed, and the second prism pitch in the region closer to the terminal end face is smaller, The plurality of regions include a first entrance region (2ga1) into which the incident light reflected X times (X is an integer equal to or greater than 1) by the first reflecting portion is incident, and a second entrance region (2ga2) into which the incident light reflected (X+1) times by the first reflecting portion is incident, The optical member according to claim 12 , wherein the first entrance region has a second prism pitch different from that of the second entrance region.

19. a pitch interval of the second prism portions in the light guiding direction is constant, the reflection exit surface has a plurality of regions (2fa, 2fb) having different first prism pitches, which are pitch intervals of the first prism portions in the light guiding direction, The first prism pitch in each of the plurality of regions is fixed, and the first prism pitch in the region closer to the terminal end face is smaller, The plurality of regions include a first reflective region (2fa) that reflects the incident light to the incident surface, and a second reflective region (2fb) that reflects the incident light to the reflective surface, The optical member according to claim 12 , wherein the first prism pitch of the first reflecting region is different from that of the second reflecting region.

Images