Optical Components

Abstract

To provide an optical member with which it is possible to prevent the outside scene shown to users via a transparent material from being seen displaced from the actual position.SOLUTION: A second plane 25 is provided on the opposite side to a first plane 16 in a transparent material 12. A plurality of prism parts 162 of the first plane 16 include a prism emission plane 162a, and this prism emission plane 162a emits outside scene light reflected by the second plane 25 to the outside of the transparent material 12. The second plane 25 is tilted with respect to a flat plane 161 so as to progressively depart from the first plane 16, with one side of the same in a first direction D1 most apart. Thus, the optical path of outside scene light from the prism emission plane 162a to an eyepoint EP of a user 90 can be inclined with respect to the optical path of outside scene light from an outside scene point G to an incidence plane 15. As a result, it is made possible to bring the line of sight of the user 90 closer to the actual position of the outside scene point G and prevent the outside scene point G from being seen displaced from the actual position, as compared with the case where the second plane 25 and the flat plane 161 are parallel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical member that guides light incident on a light-transmitting body by reflecting the light inside the light-transmitting body. [Background technology]

[0002] An example of this type of optical member is described in Patent Document 1. The optical member described in Patent Document 1 includes a light guide made of a light-transmitting resin material, a semi-transmitting flat mirror, a flat mirror, and a prism sheet on which a plurality of prisms are formed.

[0003] The light guide has an entrance surface on which external scene light is incident, a first surface on which the external scene light incident from the entrance surface first reaches, and a second surface provided on the opposite side of the first surface. A semi-transmitting flat mirror is closely attached to the first surface of the light guide, and a flat mirror is closely attached to the second surface. Therefore, the semi-transmitting flat mirror and the flat mirror face each other with the light guide in between. The semi-transmitting flat mirror and the flat mirror are arranged parallel to each other.

[0004] The prism sheet is disposed on the side opposite to the light guide with respect to the semi-transmitting flat mirror, and is fixed in intimate contact with the semi-transmitting flat mirror.

[0005] With this configuration, in the optical member of Patent Document 1, a portion of the outside light incident from the incident surface is reflected by the semi-transmitting flat mirror to the second surface, and the light reflected by the semi-transmitting flat mirror is reflected by the flat mirror to the first surface. The remaining portion of the light not reflected by the semi-transmitting flat mirror is absorbed by or passes through the semi-transmitting flat mirror. The light that passes through the semi-transmitting flat mirror is emitted to the outside from the exit surfaces of the multiple prisms. The exit surfaces of the prisms are parallel to the incident surface of the light guide.

[0006] As a result, the outside scene light incident on the light guide from the incident surface is emitted over a wide range through the multiple prisms provided on the first surface different from the incident surface. A user who sees the light emitted from the multiple prisms can see the outside scene located on the opposite side of the optical member from the user through the optical member of Patent Document 1. For example, this optical member is used as a blind spot auxiliary device that is placed on a specific obstacle and allows the user to see the outside scene in a blind spot area that is blocked by the obstacle and cannot be directly seen by the user. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6372305 Summary of the Invention [Problem to be solved by the invention]

[0008] Here, in the optical member of Patent Document 1, the incident surface of the light guide and the exit surfaces of the multiple prisms are parallel, and the semi-transmissive flat mirror and the flat mirror are also parallel. Therefore, the optical path of the outside light (i.e., the exiting light) exiting from the exit surface of the prism is parallel to the optical path of the outside light immediately before it enters the incident surface of the light guide. In other words, the exiting light is a light obtained by translating the outside light immediately before it enters the incident surface. As a result, to a user who sees the outside scene in the blind spot area through the optical member of Patent Document 1, the outside scene in the blind spot area appears to be in a position displaced from the actual position. The inventors have found the above as a result of detailed studies.

[0009] In view of the above, an object of the present invention is to provide an optical member capable of suppressing the appearance of an external scene shown to a user through a light guide being shifted from its actual position. [Means for solving the problem]

[0010] In order to achieve the above object, the optical member according to claim 1 comprises: An optical member that is composed of a light guide (12) that transmits light, and that guides outside scene light that represents an outside scene by reflecting it inside the light guide, an incident surface (15) included in the outer surface of the light guide, on which external light enters from the outside of the light guide and intersects with one direction (D1); a first surface (16) that is included in the outer surface of the light guide, that is disposed on one side of the incident surface in the one direction, and that has a plurality of flat surfaces (161) and a plurality of prism portions (162) that are arranged side by side in the one direction; a second surface (25) that is included in the outer surface of the light guide, that is disposed on one side of the incident surface in the one direction, and that is provided on the light guide on the opposite side to the first surface; Each of the flat surfaces is formed as a surface parallel to the one direction, and reflects the external light incident inside the light guide toward the second surface; The second surface reflects the external light reflected by the multiple flat surfaces toward the first surface, Each of the plurality of prism portions has an exit surface (162a) parallel to the entrance surface, the exit surface emits the external light reflected by the second surface to the outside of the light guide; The second surface is inclined with respect to the flat surface so as to move away from the first surface toward one side in the one direction.

[0011] In this way, when the outside scene light reaches the user through the light guide, the optical path of the outside scene light from the exit surface of the prism section to the user's eye point can be inclined with respect to the optical path of the outside scene light from a certain outside scene point located on the second surface side of the light guide to the entrance surface. If a straight line extending the optical path of the outside scene light from the exit surface to the user's eye point toward the second surface side of the light guide is assumed, the assumed straight line can be brought closer to the outside scene point than, for example, when the second surface and the flat surface are parallel. Therefore, it is possible to suppress the positional deviation of a part of the outside scene including the outside scene point, and to show the part of the outside scene to the user.

[0012] Note that 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]

[0013] [Figure 1] FIG. 2 is a diagram showing a cross section of an optical member illustrating a state in which the optical member guides outside scene light, an outside scene point that is a certain point in the outside scene around the light guide body, and a user's eye point in the first embodiment. [Diagram 2] 2 is an enlarged cross-sectional view of the same optical member as in FIG. 1 in the first embodiment. [Diagram 3] 3 is a partial cross-sectional view showing an enlarged view of part III in FIG. 2 in the first embodiment. [Figure 4] 3 is a partial cross-sectional view showing an enlarged view of a portion IV in FIG. 2 in the first embodiment. [Diagram 5] 2 is a diagram showing a cross section of an optical member, an external scene point, and a user's eye point in a first comparative example to be compared with the first embodiment, and corresponds to FIG. 1. FIG. [Figure 6] 6 is an enlarged cross-sectional view of the same optical member as in FIG. 5 in a first comparative example, and corresponds to FIG. 2. FIG. [Figure 7] FIG. 11 is a perspective view showing a schematic configuration of an optical member in the second embodiment. [Figure 8] FIG. 11 is a cross-sectional view showing a cross section of an optical member in a second embodiment, and corresponds to FIG. [Figure 9] FIG. 11 is a cross-sectional view showing a cross section of an optical member in a third embodiment, and corresponds to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, the same reference numerals are given to parts that are the same or equivalent to each other.

[0015] (First embodiment) 1, the optical member 10 of the present embodiment is attached to, for example, an obstacle 92 that blocks the field of view of a user 90 and causes a blind spot. The optical member 10 functions as a blind spot auxiliary device that allows the user 90 to visually recognize the scene in the blind spot area that has become the blind spot of the user 90 due to the obstacle 92.

[0016] The optical member 10 is composed of a light guide 12 that transmits light, and guides outside scene light that represents an outside scene by reflecting it inside the light guide 12. For example, the optical member 10 is mounted on a vehicle, and in the case of such an in-vehicle application, the optical member 10 is attached to a pillar or the like of the vehicle on which the optical member 10 is mounted. The optical member 10 guides outside scene light from an area that is a blind spot due to the pillar, which is an obstacle 92, to the user 90 side, and allows the user 90, who is the driver of the vehicle, to view the scene in the blind spot area.

[0017] In addition, Fig. 1 shows a cross-sectional view of a vehicle pillar, which is an obstacle 92. In Fig. 1 and the figures described below, cross-sectional hatching of the optical member 10 is omitted in order to make the illustration easier to understand. In addition, the unit of angle described in this embodiment is [rad] unless otherwise specified.

[0018] 1 and 2, the light guide 12 constituting the optical member 10 of this embodiment is formed to extend in a first direction D1 and have a thickness direction in a second direction D2. The first direction D1 and the second direction D2 are directions that intersect with each other, or strictly speaking, are directions that are perpendicular to each other.

[0019] 1 and 2 are referred to as light guide cross sections. The cross-sectional shape of the light guide 12 shown in the light guide cross section is the same at any position in a third direction D3 (e.g., the direction into the depth of the paper in FIG. 2) perpendicular to each of the first direction D1 and the second direction D2, and the light guide 12 is formed so as to extend in the third direction D3 as well. Note that the first direction D1 corresponds to one direction in the present disclosure, and the second direction D2 corresponds to the flat surface normal direction in the present disclosure.

[0020] The light guide 12 is disposed on one side of the obstacle 92 in the second direction D2, and is disposed on the other side of the second direction D2 with respect to the user 90. The user 90 indirectly views a blind spot area located on the other side of the second direction D2 with respect to the light guide 12 and the obstacle 92 via the light guide 12. For example, the light guide 12 is installed inside a vehicle cabin, and is therefore disposed in the air.

[0021] The light guide 12 includes a light guide member 14 and an adjustment section 24. Both the light guide member 14 and the adjustment section 24 are, for example, colorless and transparent, and have translucency that transmits light. Therefore, the light guide 12 is also, for example, colorless and transparent, and has translucency.

[0022] The light guide member 14 and the adjustment section 24 are made of a resin material such as polyethylene terephthalate, polycarbonate, polyethylene, acrylic, or a transparent material such as glass. The light guide member 14 and the adjustment section 24 are made of the same material. Therefore, the refractive index of the light guide member 14 and the refractive index of the adjustment section 24 are the same, and therefore the refractive index n of the light guide 12 is the same as both the refractive index of the light guide member 14 and the refractive index of the adjustment section 24. In the description of this embodiment, the refractive index means the absolute refractive index.

[0023] The light-guiding member 14 has an incident surface 15, a first surface 16, a smooth surface 17, and an inclined surface 18, and the adjustment portion 24 has a second surface 25 and an opposing surface 26. The incident surface 15, the first surface 16, the inclined surface 18, and the second surface 25 are included in the outer surface of the light guide 12.

[0024] The incident surface 15 of the light guide 12 is a surface that intersects with the first direction D1 and is formed, for example, in a planar shape. The incident surface 15 is inclined with respect to the second direction D2 so that the incident surface 15 is located closer to one side of the first direction D1 than the other side of the second direction D2. External light is incident on the incident surface 15 from outside the light guide 12.

[0025] Further, the incident surface 15 has one edge 151 and the other edge 152. The one edge 151 is located at an end of the incident surface 15 on one side in the second direction D2, and the other edge 152 is located at an end of the incident surface 15 on the other side in the second direction D2.

[0026] The first surface 16 of the light guide 12 is a surface extending in the first direction D1 and the third direction D3, and is provided on one side of the light guide 12 in the second direction D2. The first surface 16 is also disposed on one side of the incident surface 15 in the first direction D1. In detail, the first surface 16 is connected to one edge 151 of the incident surface 15 at an edge on the other side of the first surface 16 opposite to the one side in the first direction D1.

[0027] Moreover, the first surface 16 has a plurality of flat surfaces 161 and a plurality of prism portions 162 arranged side by side in the first direction D1. In detail, the flat surfaces 161 and the prism portions 162 are arranged alternately in the first direction D1. The flat surfaces 161 are provided to reflect the light guided inside the light guide body 12, and the prism portions 162 are provided to emit the light guided inside the light guide body 12. That is, the flat surfaces 161 and the prism portions 162 separate the light guided inside the light guide body 12 into reflected light reflected by the first surface 16 and transmitted light transmitted through the first surface 16 by area division of the first surface 16.

[0028] In addition, the flat surface 161 and the prism portion 162 shown in the light guide cross section of Figures 1 and 2 are actually very small, but in the light guide cross section of Figures 1 and 2, they are intentionally shown larger than they actually are in order to make the illustration easier to see.

[0029] Each of the flat surfaces 161 is formed as a surface parallel to the first direction D1 and the third direction D3. For example, when a plane perpendicular to the second direction D2 is assumed, all the flat surfaces 161 are included in the assumed plane. That is, the second direction D2 is the normal direction of the flat surfaces 161.

[0030] Each of the multiple prism portions 162 protrudes toward one side in the second direction D2 from the flat surface 161. Each of the multiple prism portions 162 has a triangular cross-sectional shape in which the width in the first direction D1 narrows toward one side in the second direction D2 in the light guiding cross section in Figures 1 and 2. As can be seen from Figures 1 and 2, the light guiding cross section is a cross section obtained by cutting the light guiding cross section by a plane perpendicular to each of the incident surface 15 and the flat surface 161.

[0031] As described above, each of the prism portions 162 has a triangular cross-sectional shape, and thus has a prism exit surface 162a and a prism other surface 162b that are connected to each other at the apex of the triangular cross-sectional shape. Both the prism exit surface 162a and the prism other surface 162b are inclined surfaces that are inclined with respect to the second direction D2.

[0032] In detail, prism exit surface 162a corresponds to the exit surface of the present disclosure, and is a plane parallel to incident surface 15. Therefore, as shown in Fig. 3 and Fig. 4, prism exit surface 162a, like incident surface 15, is inclined with respect to second direction D2 so as to be located on one side of first direction D1 toward the other side of second direction D2. Conversely, prism other surface 162b is inclined with respect to second direction D2 so as to be located on the other side of first direction D1 toward the other side of second direction D2. In addition, prism exit surface 162a faces the opposite side to incident surface 15.

[0033] 1 and 2, the inclined surface 18 of the light guide 12 is provided on the other side in the second direction D2 with respect to the first surface 16. That is, the inclined surface 18 is provided on the side of the light guide 12 opposite to the first surface 16.

[0034] Moreover, inclined surface 18 is inclined with respect to second direction D2 so that the more it is positioned on the other side of first direction D1 in the second direction D2, the more it is positioned on the other side of first direction D1. In particular, inclined surface 18 is connected to the other edge 152 of incident surface 15 at an edge of inclined surface 18 on the other side in first direction D1.

[0035] The smooth surface 17 of the light guide member 14 is formed as a plane parallel to the first direction D1 and the third direction D3. Therefore, the smooth surface 17 is parallel to the flat surface 161.

[0036] The smooth surface 17 is provided on the other side of the first surface 16 in the second direction D2. That is, the smooth surface 17 is provided on the side of the light guide member 14 opposite to the first surface 16.

[0037] Moreover, the smooth surface 17 is disposed on one side in the first direction D1 with respect to the inclined surface 18. In detail, an edge of the inclined surface 18 on one side in the first direction D1 and an edge of the smooth surface 17 on the other side in the first direction D1 are connected to each other.

[0038] The adjustment unit 24 is provided on the other side in the second direction D2 with respect to the smooth surface 17 of the light guiding member 14. The opposing surface 26 of the adjustment unit 24 is provided on one side in the second direction D2 of the adjustment unit 24 and is formed as a flat surface parallel to the first direction D1 and the third direction D3.

[0039] The opposing surface 26 faces the smooth surface 17 in the second direction D2 and is joined to the smooth surface 17. As a result, the light-guiding member 14 and the adjustment unit 24 are integrated to form the light guide 12. In detail, the adjustment unit 24 is connected to the smooth surface 17 of the light-guiding member 14 by being index-matched. Therefore, the light beam traveling inside the light guide 12 can pass through the smooth surface 17 and the opposing surface 26 without being refracted or reflected.

[0040] The second surface 25 of the light guide 12 is formed as a plane that is slightly inclined with respect to the first direction D1. In detail, the second surface 25 is inclined with respect to the first direction D1 so as to be located on the other side of the second direction D2 toward one side of the first direction D1. In other words, the second surface 25 is inclined with respect to the flat surface 161 so as to be away from the first surface 16 toward one side of the first direction D1.

[0041] The second surface 25 is provided on the other side in the second direction D2 with respect to the opposing surface 26 and the first surface 16. That is, the second surface 25 is provided on the side of the light guide 12 opposite to the first surface 16.

[0042] In addition, the second surface 25 is disposed on one side of the inclined surface 18 in the first direction D1, and is therefore disposed on one side of the incident surface 15 in the first direction D1. The second surface 25 has an incident side edge 251. This incident side edge 251 is located at the end of the second surface 25 on the other side of the first direction D1. That is, the incident side edge 251 is located at the end of the second surface 25 on the incident surface 15 side. In this embodiment, the adjustment unit 24 has a triangular cross-sectional shape in the light guide cross section of FIG. 1 and FIG. 2, so that the incident side edge 251 of the second surface 25 coincides with the edge of the opposing surface 26 on the other side of the first direction D1. Therefore, the incident side edge 251 of the second surface 25 also coincides with the edge of the smooth surface 17 on the other side of the first direction D1. The second surface 25 is connected at an incident side edge 251 of the second surface 25 to an edge that the inclined surface 18 has on one side in the first direction D1.

[0043] In addition, in the second direction D2, the incident side edge 251 of the second surface 25 is located between one edge 151 and the other edge 152 of the incident surface 15. That is, the incident surface 15 is formed so as to expand from one side to the other side in the second direction D2 with respect to the incident side edge 251. In other words, the relationship between the distance Td along the second direction D2 between the other edge 152 of the incident surface 15 and the flat surface 161 and the distance T along the second direction D2 between the incident side edge 251 of the second surface 25 and the flat surface 161 is "Td>T".

[0044] In the description of this embodiment, the distance Td between the other edge 152 of the incident surface 15 and the flat surface 161 in the second direction D2 is referred to as the incident surface height Td. Also, the distance T between the incident-side edge 251 of the second surface 25 and the flat surface 161 in the second direction D2 is the same as the distance between the smooth surface 17 and the flat surface 161 in the second direction D2, and in the description of this embodiment, is referred to as the light-guiding member thickness T.

[0045] 1 and 2, the external scene light that enters the entrance surface 15 from outside the light guide 12 and reaches the eye point EP of the user 90 includes a predetermined light ray Ls that enters the entrance surface 15 from an external scene point G, which is a point located outside the light guide 12. The predetermined light ray Ls enters the entrance surface 15 from the external scene point G, passes through the inside of the light guide 12, and reaches the eye point EP of the user 90. The eye point EP of the user 90 is the position of the eyes of the user 90. In addition, the predetermined light ray Ls is included in the external scene light, and is therefore a visible light ray.

[0046] The external scene point G is included in a blind spot area for the user 90. In detail, the external scene point G is located on the other side of the second direction D2 with respect to the light guide 12, and is located on a virtual straight line LN1 that intersects with a specific exit surface 162c (see FIG. 4), which is one of the multiple prism exit surfaces 162a. On the other hand, the eye point EP of the user 90 is located on one side of the second direction D2 with respect to the light guide 12, and is located on the virtual straight line LN1.

[0047] Furthermore, since the optical element 10 of this embodiment functions as a blind spot auxiliary device mounted on a vehicle, the distance from the light guide 12 to the external scene point G is actually much longer than the distance from the light guide 12 to the eye point EP, unlike the schematic diagram shown in FIG. 1.

[0048] Furthermore, the predetermined light ray Ls is reflected by any one of the flat surfaces 161 and the second surface 25 inside the light guide 12, and after being reflected in this manner, is emitted from the specific emission surface 162c of the prism portion 162 to the outside of the light guide 12 in a direction along the virtual straight line LN1. In other words, the predetermined light ray Ls is emitted from the specific emission surface 162c of the prism portion 162 to the eyepoint EP of the user 90 along the virtual straight line LN1.

[0049] In addition, the predetermined light ray Ls is refracted or reflected by the light guide 12 and travels, and therefore has a number of light rays Li, L1, L2, L3, and Lo that travel in a straight line. For example, in this embodiment, the predetermined light ray Ls has a pre-entry light ray Li, a first light ray L1, a second light ray L2, a third light ray L3, and an exit light ray Lo. The multiple light rays Li, L1, L2, L3, and Lo are connected in series in the order of the pre-entry light ray Li, the first light ray L1, the second light ray L2, the third light ray L3, and the exit light ray Lo from the upstream side of the optical path of the predetermined light ray Ls. In Figs. 1 and 2, the multiple light rays Li, L1, L2, L3, and Lo are respectively represented by arrows. In addition, Figs. 1 and 2 show how the predetermined light ray Ls enters the inside of the light guide 12 from the entrance surface 15 and is guided inside the light guide 12.

[0050] As shown in Figs. 1 to 4, the pre-incident ray Li of the predetermined light ray Ls is a light ray from an external scene point G until it is incident on the incident surface 15, and the first light ray L1 is a light ray from the incident surface 15 until it is first reflected by the flat surface 161. The second light ray L2 is a light ray from the flat surface 161 that reflected the first light ray L1 until it is first reflected by the second surface 25, and the third light ray L3 is a light ray from the second surface 25 that reflected the second light ray L2 to the specific exit surface 162c of the prism section 162. The exit light ray Lo is a light ray from the specific exit surface 162c of the prism section 162 to the eyepoint EP of the user 90, that is, a light ray that is exited from the specific exit surface 162c to the outside of the light guide 12 and heads toward the eyepoint EP of the user 90.

[0051] For example, as shown by the pre-incident light ray Li, the incident direction Di when the predetermined light ray Ls is incident on the incident surface 15 is inclined with respect to the second direction D2 such that a straight line parallel to the incident direction Di is located on one side of the first direction D1 toward one side of the second direction D2. In other words, the incident direction Di of the predetermined light ray Ls is a direction parallel to the pre-incident light ray Li.

[0052] As shown by the pre-entry light Li and the first light L1, the predetermined light Ls is refracted at the incident surface 15 and enters the light guide 12. Then, as shown by the first light L1, the outside scene light representing the outside scene on the other side of the light guide 12 in the second direction D2 and entering the light guide 12 from the incident surface 15 first reaches the first surface 16 of the first surface 16 and the second surface 25 from the incident surface 15. Specifically, the predetermined light Ls (specifically, the first light L1) reaches a specific flat surface 161a, which is one flat surface 161 of the multiple flat surfaces 161 of the first surface 16, without being reflected from the incident surface 15. Then, the specific flat surface 161a reflects the first light L1 at a reflection point PA of the specific flat surface 161a. As exemplified by the first light ray L1 and the second light ray L2, each of the flat surfaces 161 reflects the external light that has entered the inside of the light guide 12 toward the second surface 25.

[0053] Furthermore, the second surface 25 reflects the outside light reflected by the multiple flat surfaces 161 toward the first surface 16, as exemplified by the second light ray L2 and the third light ray L3.

[0054] As shown by the third light ray L3 and the exit light ray Lo, the predetermined light ray Ls is refracted at the specific exit surface 162c of the prism section 162 and is exited to the outside of the light guide 12. In detail, the predetermined light ray Ls is reflected at the specific flat surface 161a and further reflected at the second surface 25, and then reaches the specific exit surface 162c of the prism section 162. The specific exit surface 162c has an exit point PB which is an intersection point where the predetermined light ray Ls and the specific exit surface 162c intersect, and the predetermined light ray Ls is refracted at the exit point PB and is exited to the eye point EP of the user 90 outside the light guide 12. Then, as shown by the third light ray L3 and the exit light ray Lo, the multiple prism exit surfaces 162a including the specific exit surface 162c exit the outside scene light reflected at the second surface 25 to the outside of the light guide 12.

[0055] Of the external light that reaches the first surface 16 inside the light guide 12, the light that reaches the prism exit surface 162a is emitted from the prism exit surface 162a to the outside of the light guide 12, and the light that reaches the flat surface 161 is reflected toward the second surface 25.

[0056] In order to obtain good performance as a blind spot auxiliary device, the optical member 10 of this embodiment is designed under various conditions as shown below. For example, when the incident angle of the predetermined light ray Ls to the specific flat surface 161a is φ and the refractive index of the light guide 12 is n, the light guide 12 satisfies the following formula F1. In other words, the incident angle φ is the angle that the first light ray L1 of the predetermined light ray Ls forms with respect to the normal line LV1 of the specific flat surface 161a. When the following formula F1 is satisfied, the specific flat surface 161a totally reflects the predetermined light ray Ls. Note that in FIG. 2, angles φ, θi, ψ, ξ, and ζ with positive values ​​are each displayed. Also, the angles φ, θi, ψ, ξ, and ζ included in the following formula F1 or the relational expressions described below are all angles less than π / 2 [rad]. sinφ>1 / n (F1)

[0057] In addition, when the incident inclination angle, which is the angle between the incident direction Di of the predetermined light ray Ls and the second direction D2, is θi, and the angle between the incident surface 15 and the second direction D2 is ψ, the light guide 12 satisfies the following formula F2 and also satisfies the following formula F3. In the following formulas F2 and F3, the angle φ is the incident angle of the predetermined light ray Ls with respect to the specific flat surface 161a, as described above. The definition of this angle φ is the same in the relational expressions described later. θi<φ (F2) ψ<φ (F3)

[0058] In addition, in the light guide cross section of Figure 2, if the angle that a virtual line segment LN2 connecting the incident side edge 251 of the second surface 25 and the other edge 152 of the incident surface 15 makes with the second direction D2 is ξ, the light guide 12 satisfies the following formula F4. ξ<φ (F4)

[0059] Furthermore, in the light guide cross section of Figures 1 and 2, if the distance along the first direction D1 between the reflection point PA and the emission point PB is H, the distance between the eye point EP of the user 90 and the external scene point G is D, and the angle at which the second surface 25 is inclined with respect to the first direction D1 is ζ, the relationship of the following formula F5 holds. ζ=1 / 2×[arccos{cos(θi+ψ+arcsin(H×cosθi / D)) / n}+arcsin{cos(ψ+θi) / n}-π / 2] ···(F5)

[0060] In the above formula F5, the angles θi, ψ, and the refractive index n are defined as described above. That is, the angle θi is the angle between the incident direction Di of the predetermined light ray Ls and the second direction D2, the angle ψ is the angle between the incident surface 15 and the second direction D2, and the refractive index n is the refractive index of the light guide 12. The angles ζ, θi, and ψ included in the above formula F5 are all in units of [rad]. In addition, "arccos" described in this embodiment is a function that gives an angle within the range of 0 to π [rad], and "arcsin" is a function that gives an angle within the range of -π / 2 to π / 2 [rad].

[0061] In the description of this embodiment, the distance D between the eye point EP of the user 90 and the external scene point G is referred to as the display distance D, and the angle ζ at which the second surface 25 is inclined with respect to the first direction D1 is referred to as the second surface inclination angle ζ. Also, the distance H along the first direction D1 between the reflection point PA and the emission point PB in FIG. 1 is referred to as the light guiding distance H.

[0062] 2, the light guide 12 satisfies the following formula F6, where m is the number of times that the predetermined light ray Ls is reflected by the second surface 25 inside the light guide 12, T is the distance along the second direction D2 between the incident side edge 251 of the second surface 25 and the flat surface 161, and Wx is the width that the second surface 25 occupies in the first direction D1. Note that in this embodiment, the number m of times that the predetermined light ray Ls is reflected by the second surface 25 inside the light guide 12 is one time. Wx≧m×2×T×tanφ (F6)

[0063] Next, the effects of the optical member 10 of this embodiment will be described. According to this embodiment, the second surface 25 is provided on the side of the light guide 12 opposite to the first surface 16. The multiple prism portions 162 of the first surface 16 have a prism exit surface 162a, which emits the outside light reflected by the second surface 25 to the outside of the light guide 12. The second surface 25 is inclined with respect to the flat surface 161 so as to be away from the first surface 16 toward one side in the first direction D1.

[0064] As a result, when the outside scene light reaches the user 90 through the light guide 12, the optical path of the outside scene light from the prism exit surface 162a to the eye point EP of the user 90 can be inclined with respect to the optical path of the outside scene light from a certain point (for example, an outside scene point G in FIG. 1) located on the other side of the outside scene in the second direction D2 with respect to the light guide 12 to the entrance surface 15. If a straight line (for example, a virtual straight line LN1 in FIG. 1) extending the optical path of the outside scene light from the prism exit surface 162a to the eye point EP to the other side of the second direction D2 is assumed, the assumed straight line can be brought closer to the certain point in the outside scene than, for example, when the second surface 25 and the flat surface 161 are parallel. Therefore, it is possible to suppress the positional deviation of a part of the outside scene including the certain point, and to show the part of the outside scene to the user 90.

[0065] Here, in order to describe in detail the above-mentioned operational effects of the optical member 10 of this embodiment, a first comparative example shown in Figs. 5 and 6 will be described. As shown in Figs. 5 and 6, the light guide 72 constituting the optical member 70 of the first comparative example has the light guide member 14 but does not have the adjustment section 24. Therefore, the light guided inside the light guide 72 is reflected by the smooth surface 17. In other words, the first comparative example is the same as the case where the angle ζ (see Fig. 1) in this embodiment is set to "ζ=0". Except for these points, the optical member 70 of the first comparative example is the same as the optical member 10 of this embodiment.

[0066] 5 and 6, in the first comparative example, it is assumed that the same pre-incident light ray Li as in FIG. 1 is incident on the incident surface 15 of the light guide 72 from the same external scene point G as in FIG. 1. In this case, the smooth surface 17 and the flat surface 161 are parallel, and the incident surface 15 and the prism exit surface 162a are also parallel, so that the pre-incident light ray Li from the external scene point G until it enters the incident surface 15 is parallel to the exit light ray Loa exiting from the specific exit surface 162c of the prism section 162. Then, the predetermined light ray Ls is guided in the first direction D1 while being reflected one or more times inside the light guide 72, so that the exit light ray Loa is a parallel translation of the pre-incident light ray Li.

[0067] Therefore, a user 90 who sees an external scene point G through the light guide 72 of the first comparative example recognizes that the external scene point G is at an external scene recognition position Ga that is away from the actual external scene point G by a positional shift distance ΔGm. As for the direction, the user 90 recognizes that the external scene point G is at an external scene recognition position Ga that is shifted in direction from the actual external scene point G by a positional shift angle θm.

[0068] The positional deviation distance ΔGm is obtained from the following formula F7 based on the light guide distance H of the light guide 12 and the inclination angle θi at the time of incidence of the specific light ray Ls. At this time, the distance A0 between the intersection point of the extension line of the pre-incident light ray Li and the flat surface 161 and the reflection point PA of the specific flat surface 161a is very small, so it is considered that "A0 = 0", and the following formula F7 is derived. ΔGm = H × cosθi (F7)

[0069] In the first comparative example, the predetermined light ray Ls is reflected once by the smooth surface 17 inside the light guide 12, so the light guide distance H in the above formula F7 is obtained from the following formula F8 based on the incident angle φ of the predetermined light ray Ls with respect to the specific flat surface 161a and the light guide member thickness T. In this case, since the prism portion 162 is very small, the prism portion 162 having the exit point PB is considered not to protrude from the flat surface 161, and the following formula F8 is derived. H ≒ 2 × T × tanφ (F8)

[0070] The positional misalignment angle θm is obtained from the following formula F9 based on the light guide distance H of the light guide 12, the inclination angle θi at the time of incidence of the predetermined light ray Ls, and the display distance D. This formula F9 is derived based on the above formula F7, as shown in FIG. θm=arcsin(H×cosθi / D) ···(F9)

[0071] In contrast to the first comparative example described above, in this embodiment, as shown in Figures 1 and 2, the line of sight of a user 90 looking at, for example, an external scene point G is aligned along the virtual straight line LN1 in Figure 1. Therefore, as described above, it is possible to suppress positional deviation of a partial area of ​​the external scene that includes, for example, the external scene point G, and to show the partial area of ​​the external scene to the user 90.

[0072] (1) Furthermore, according to this embodiment, the light guide 12 has a light guide member 14 having an entrance surface 15 and a first surface 16, and an adjustment section 24 having a second surface 25. The refractive index of the light guide member 14 and the adjustment section 24 are the same, and the adjustment section 24 is index-matched and connected to the smooth surface 17 of the light guide member 14. Therefore, it is possible to prevent the outside light guided inside the light guide 12 from being refracted or reflected at the boundary between the light guide member 14 and the adjustment section 24, and it is possible to arbitrarily determine the second surface inclination angle ζ by replacing the adjustment section 24.

[0073] (2) According to this embodiment, the external scene light guided by the light guide 12 includes a predetermined light ray Ls that is incident on the entrance surface 15 from an external scene point G located on the virtual straight line LN1. The predetermined light ray Ls is guided while being reflected inside the light guide 12, and is emitted from the specific emission surface 162c of the first surface 16 in a direction along the virtual straight line LN1 to the eye point EP of the user 90 located outside the light guide 12. Therefore, the line of sight of the user 90 is directed toward the external scene point G along the virtual straight line LN1, and the user 90 can view the external scene point G without any positional deviation.

[0074] (3) According to the present embodiment, the light guide 12 satisfies the above formula F1. Therefore, all reflections of the predetermined light ray Ls by the flat surface 161 are total reflections. Furthermore, since the second surface 25 is inclined with respect to the first direction D1 so as to be located on the other side of the second direction D2 toward one side of the first direction D1, the second surface 25 also totally reflects the predetermined light ray Ls inside the light guide 12. Therefore, compared with the case where the reflection by the flat surface 161 is not total reflection, for example, the amount of light reaching the user 90 is increased, so that the outside scene displayed by the optical member 10 can be made to look brighter to the user 90 without positional deviation.

[0075] (4) According to the present embodiment, the light guide 12 satisfies the above formula F4. Here, for example, a second comparative example is assumed in which the relationship "ξ>φ" holds, which is the opposite of the above formula F4. In this case, in the second comparative example, the first light ray L1 having the incident angle φ moves away from the imaginary line segment LN2 connecting the incident side edge 251 of the second surface 25 and the other edge 152 of the incident surface 15 toward the downstream side of the optical path of the first light ray L1.

[0076] Therefore, in the second comparative example, a gap is always created between the light beam that is incident parallel to the first light beam L1 from the vicinity of the other end edge 152 of the incident surface 15 and the incident side end edge 251 of the second surface 25. That is, a gap (in other words, a gap between the light beams) is always created between the bundle of light beams that is incident parallel to the first light beam L1 from the incident surface 15 and the light beam reflected by the second surface 25 near the incident side end edge 251 of the second surface 25. Therefore, among the multiple prism portions 162, between the prism portions 162 to which the predetermined light beam Ls or a light beam parallel to the predetermined light beam Ls has reached, a prism portion 162 to which neither the predetermined light beam Ls nor a light beam parallel to the predetermined light beam Ls has reached may be created. As a result, when a partial area including the external scene point G in FIG. 1 is visually recognized by the user 90, the continuity of the display of the light guide 12 is impaired.

[0077] In contrast, in this embodiment, the above formula F4 is satisfied, and therefore no gaps in the light rays occur. Therefore, when the user 90 is made to view a partial area including the external scene point G in FIG. 1, it is possible to ensure the continuity of the display of the light guide 12.

[0078] (5) Furthermore, according to this embodiment, the relationship of the above formula F5 is established. Therefore, it is possible to easily determine the shape of the adjustment portion 24 using the above formula F5.

[0079] Here, the derivation of the above formula F5 will be explained with reference to Fig. 1 to Fig. 4. First, assume a hypothetical configuration in which the second surface inclination angle ζ is 0 and the second surface 25 is parallel to the flat surface 161, specifically, the configuration of the above-mentioned first comparative example. In that case, since the prism exit surface 162a and the entrance surface 15 are also parallel, as shown in Fig. 3 and Fig. 4, if the angle of incidence of the pre-entry ray Li with respect to the entrance surface 15 is angle θ0, the exit angle that the exit ray Loa exiting from the specific exit surface 162c makes with respect to the normal to the specific exit surface 162c is also angle θ0.

[0080] At this time, the positional deviation angle θm in Fig. 4 occurring between the emergent light beam Loa of the first comparative example and the emergent light beam Lo of this embodiment can be obtained from the above formula F9 used in the explanation of the first comparative example. In addition, since the positional deviation angle θm is very small, it can be considered that the light guide distance H of the light guide body 12 of this embodiment is the same as that of the first comparative example. In other words, it can be considered that the emergence point PB of the specific emergent surface 162c is the same between the first comparative example and this embodiment.

[0081] Therefore, if the emergence angle θ2a that the emergent light ray Lo of this embodiment makes with respect to the normal line of the specific emergent surface 162c satisfies the following formula F10, the external scene point G can be visually recognized by the user 90 without positional deviation. In short, by tilting the second surface 25 and rotating the emergent light ray Loa of the first comparative example counterclockwise by the positional deviation angle θm in FIG. 4, the external scene point G can be visually recognized by the user 90 without positional deviation. θ2a = θ0 - θm (F10)

[0082] Moreover, from Snell's law, the following formula F11 holds: In the following formula F11, n is the refractive index of the light guide 12, and θ2 is the angle of incidence of the third light ray L3 with respect to the specific emission surface 162c. n × sinθ2 = sinθ2a (F11)

[0083] Moreover, the reflection angle θ2b of the third light ray L3 with respect to the second surface 25 can be obtained from the following formula F12. Moreover, since the entrance surface 15 and each prism exit surface 162a are parallel to each other, the normal to the specific exit surface 162c is inclined at an angle ψ with respect to the flat surface 161. Taking this into consideration, the following formula F13 can be obtained from the following formula F12. θ2b=φ+ζ (F12) θ2=π / 2-ψ-φ-2×ζ (F13)

[0084] Moreover, the following formula F14 is obtained from the above formulas F10, F11, and F13. Then, when the angle θ0 in the following formula F14 is obtained as the angle of incidence of the pre-incident light ray Li, the following formula F15 is established, and the following formula F16 is obtained from the following formulas F14 and F15. n×sin(π / 2-ψ-φ-2×ζ)=sin(θ0-θm) ···(F14) θ0=π / 2−ψ−θi (F15) n×sin(π / 2-ψ-φ-2×ζ)=sin(π / 2-ψ-θi-θm) ...(F16)

[0085] Furthermore, by transforming the above formula F16, the above formula F16 becomes the following formula F17, the following formula F18 is obtained from the following formula F17, and further the following formula F19 is obtained from the following formula F18. n×cos(ψ+φ+2×ζ)=cos(ψ+θi+θm) ···(F17) ψ+φ+2×ζ=arccos{cos(ψ+θi+θm) / n} ···(F18) 2×ζ=arccos{cos(ψ+θi+θm) / n}-ψ-φ ···(F19)

[0086] According to Snell's law, the following formula F20 is satisfied between the incident angle θ0 of the pre-incident light ray Li with respect to the incident surface 15 and the refraction angle θ0a of the first light ray L1 with respect to the incident surface 15. The incident angle φ of the first light ray L1 with respect to the specific flat surface 161a is obtained from the following formula F21. sinθ0 = n × sinθ0a (F20) φ=π / 2−ψ−θ0a (F21)

[0087] Furthermore, the following formula F22 is obtained from the above formula F19 and the above formula F21, and the following formula F23 is obtained from the below formula F22 and the above formula F20. 2×ζ=arccos{cos(ψ+θi+θm) / n} -ψ-π / 2+ψ+θ0a ········(F22) 2×ζ=arccos{cos(ψ+θi+θm) / n} -π / 2+arcsin(sinθ0 / n) ···(F23)

[0088] Furthermore, the following formula F24 is obtained from the above formula F23 and the above formula F15, and by transforming the below formula F24, the following formula F25 is obtained, and the above formula F5 is obtained from the below formula F25 and the above formula F9. ζ=1 / 2×[arccos{cos(ψ+θi+θm) / n} +arcsin{sin(π / 2-ψ-θi) / n}-π / 2] ···(F24) ζ=1 / 2×[arccos{cos(ψ+θi+θm) / n} +arcsin{cos(ψ+θi) / n}-π / 2] ···(F25) This concludes the explanation of the derivation of the above formula F5.

[0089] (6) Furthermore, according to this embodiment, the light guide 12 satisfies the above formula F6. Therefore, the size of the second surface 25 can be made large enough to reflect the predetermined light ray Ls incident on the inside of the light guide 12 at the second surface 25. That is, as can be seen from the above formula F8, it is possible to make the reflection of the predetermined light ray Ls on the other side of the second direction D2 be reflected at the second surface 25 until the predetermined light ray Ls incident on the inside of the light guide 12 is emitted from the first surface 16. As a result, the direction of the predetermined light ray Ls emitted from the light guide 12 to the user 90 can be adjusted at the second surface 25.

[0090] Second embodiment Next, a second embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described. Also, parts that are the same as or equivalent to the above-mentioned embodiment will be omitted or simplified. This also applies to the following embodiments.

[0091] 7 and 8, in this embodiment, the adjustment portion 24 included in the light guide 12 is different from that in the first embodiment. Also, unlike the first embodiment, the second surface inclination angle ζ of the light guide 12 is adjustable. Note that in FIG. 7, the flat surfaces 161 and the prism portions 162 of the first surface 16 of the light guide 12 are not shown.

[0092] Specifically, the adjustment unit 24 of this embodiment has a structure in which the inside of the adjustment unit 24 is filled with a liquid having the same refractive index as the light-guiding member 14. In addition, the side surfaces of the adjustment unit 24, except for the second surface 25 and the opposing surface 26, have a bellows structure and are expandable and contractible. In addition, the incident side edge 251 of the second surface 25 is connected to a rotation shaft 31 extending along a third direction D3. The third direction D3 is perpendicular to each of the first direction D1 and the second direction D2.

[0093] As a result, second surface 25 is able to swing about rotation axis CL parallel to third direction D3 as indicated by arrows A1 and A2. That is, adjustment unit 24 changes second surface inclination angle ζ, which is the same as the angle between second surface 25 and smooth surface 17, as adjustment unit 24 expands and contracts.

[0094] The direction of the emitted light ray Lo also oscillates as indicated by an arrow A3 in accordance with the oscillation of the second surface 25. For example, as the second surface inclination angle ζ of the light guide 12 increases due to the oscillation of the second surface 25, the emitted light ray angle θ3 that the emitted light ray Lo makes with respect to the first direction D1 decreases.

[0095] Also provided are a tank 32 that stores the liquid that fills the adjustment unit 24, and a pipe 33. The pipe 33 connects the tank 32 and the adjustment unit 24 so that the liquid filling the adjustment unit 24 can flow between the tank 32 and the adjustment unit 24. Also, the liquid in the tank 32 is pressurized so as to flow to the adjustment unit 24 by the action of a pump (not shown) or gravity.

[0096] Therefore, even when the adjustment section 24 expands or contracts, the inside of the adjustment section 24 is always filled with liquid having the same refractive index as the light-guiding member 14, so that the adjustment section 24 is configured to be expandable while maintaining the refractive index of the adjustment section 24 the same as that of the light-guiding member 14.

[0097] For example, an adjustment screw 34 is attached to the second surface 25 of the adjustment part 24, and the position of an end portion of the second surface 25 on one side in the first direction D1 is moved in the second direction D2 as shown by the arrow A4 by the adjustment screw 34. This causes the second surface 25 to swing about the rotation axis CL, and the second surface inclination angle ζ changes.

[0098] (1) As described above, according to this embodiment, the adjustment unit 24 is filled with a liquid having the same refractive index as the light guiding member 14, and is configured to be expandable and contractible while maintaining the refractive index of the adjustment unit 24 the same as that of the light guiding member 14. The adjustment unit 24 changes the second surface inclination angle ζ as the adjustment unit 24 expands and contracts. Therefore, even if the display distance D (see FIG. 1) between the eye point EP of the user 90 and the external scene point G changes, the orientation of the second surface 25 can be adjusted according to the display distance D, and the user 90 can view the external scene point G (see FIG. 1) without positional deviation.

[0099] Except for the points described above, this embodiment is similar to the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0100] Third embodiment Next, a third embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0101] As shown in Figure 9, in this embodiment, a specific light ray Ls from an external scene point G enters the inside of the light guide 12, is reflected twice by the second surface 25, and then is emitted from the light guide 12 toward the eye point EP of the user 90.

[0102] 9, the number m of times that the predetermined light ray Ls is reflected by the second surface 25 inside the light guide 12, i.e., the number m included in the above formula F6, is 2. Therefore, in this embodiment, with respect to the width Wx that the second surface 25 occupies in the first direction D1, the following formula F6-1 is established from the above formula F6. Wx≧4×T×tanφ (F6-1)

[0103] The predetermined light ray Ls includes the pre-incident light ray Li, the first to third light rays L1, L2, L3, and the emerging light ray Lo, as well as a fourth light ray L4 and a fifth light ray L5 between the third light ray L3 and the emerging light ray Lo.

[0104] Except for the above description, this embodiment is similar to the first embodiment. In this embodiment, the effects achieved by the configuration common to the first embodiment can be obtained in the same manner as the first embodiment. Note that this embodiment is a modification based on the first embodiment, but it is also possible to combine this embodiment with the second embodiment described above.

[0105] (Other embodiments) (1) In each of the above-described embodiments, for example as shown in FIG. 1, the external scene light incident on the incident surface 15 from outside the light guide 12 includes a specific light ray Ls from an external scene point G. However, in addition to the specific light ray Ls, the external scene light may also include light rays other than the specific light ray Ls.

[0106] (2) In each of the above-described embodiments, as shown in Fig. 1 and Fig. 2, the light-guiding member 14 has the inclined surface 18 inclined with respect to the first direction D1, and the incident surface height Td is greater than the light-guiding member thickness T, but this is just one example. For example, it is also conceivable that the inclined surface 18 is not inclined with respect to the first direction D1 but is parallel to the first direction D1, and the incident surface height Td is the same as the light-guiding member thickness T.

[0107] (3) In each of the above-described embodiments, the prism portions 162 of the light guide 12 each have a triangular cross-sectional shape in the light guide cross section of Fig. 2, but this is merely an example. For example, the prism portion 162 may have a trapezoidal cross-sectional shape in the light guide cross section. In addition, all of the prism portions 162 of the light guide 12 do not need to have the same shape.

[0108] (4) The present invention is not limited to the above-described embodiment, and can be practiced in various modified forms. Furthermore, the above-described embodiments are not unrelated to each other, and can be appropriately combined, except in cases where the combination is clearly impossible.

[0109] In each of the above embodiments, the elements constituting the embodiment are not necessarily essential, unless otherwise specified as essential or considered to be obviously essential in principle. 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 specified as essential or when they are obviously limited to a specific number in principle. In each of the above embodiments, when the materials, shapes, positional relationships, etc. of the components are mentioned, they are not limited to the materials, shapes, positional relationships, etc., except when specified as essential or when they are obviously limited to a specific material, shape, positional relationship, etc. in principle. [Explanation of symbols]

[0110] 10 Optical components 12 Light guide 15 Entrance plane 16 Front page 25 Side 2 161 Flat surface 162 Prism section 162a Prism exit surface (injection surface) D1 1st direction (one direction)

Claims

1. An optical element that is composed of a light-transmitting light guide (12) and that guides outside scene light representing an outside scene by reflecting it inside the light guide, An incident surface (15) included in the outer surface of the light guide, into which the external scene light is incident from the outside of the light guide and intersects with one direction (D1); A first surface (16) is included in the outer surface of the light guide, is disposed on one side of the incident surface in the one direction, and has a plurality of flat surfaces (161) and a plurality of prism portions (162) arranged side by side in the one direction; a second surface (25) that is included in the outer surface of the light guide, that is disposed on the one side of the incident surface in the one direction, and that is provided on the opposite side of the light guide to the first surface; The plurality of flat surfaces are each formed as a surface parallel to the one direction, and reflect the external scene light incident inside the light guide toward the second surface, the second surface reflects the outside scene light reflected by the plurality of flat surfaces toward the first surface, Each of the plurality of prism portions has an exit surface (162a) parallel to the entrance surface, the exit surface exits the outside light reflected by the second surface to an outside of the light guide body, The second surface is inclined with respect to the flat surface so as to move away from the first surface toward the one side in the one direction.

2. The light guide body includes a light guide member (14) having the incident surface and the first surface, and an adjustment section (24) having the same refractive index as the light guide member and having the second surface, The light guide member has a smooth surface (17) parallel to the flat surface, The optical member according to claim 1 , wherein the adjustment portion is connected to the smooth surface by being index-matched.

3. 3. The optical element of claim 2, wherein the adjustment portion is filled with a liquid having the same refractive index as the light-guiding member, and is configured to be expandable while maintaining the refractive index of the adjustment portion the same as that of the light-guiding member, and the angle (ζ) between the second surface and the smooth surface changes as the adjustment portion expands.

4. The first surface is provided on one side of the second surface in a flat surface normal direction (D2) that is a normal direction of the flat surface, The external scene light includes a predetermined light ray (Ls) incident on the incident surface from a certain external scene point (G) disposed outside the light guide, The external scene point is located on the other side opposite to the one side in the direction of the normal to the flat surface of the light guide, and on a virtual straight line (LN1) that intersects with a specific emission surface (162c) that is one of the plurality of emission surfaces; 4. The optical element according to claim 1, wherein the specified light ray is reflected by one of the plurality of flat surfaces and the second surface inside the light guide, and then emitted from the specific emission surface to the outside of the light guide in a direction along the virtual straight line.

5. The light guide is disposed in air, The plurality of flat surfaces includes a specific flat surface (161a) on which the predetermined light ray reaches without being reflected from the incident surface, 5. The optical member according to claim 4, wherein the light guide satisfies "sin φ>1 / n", where φ is an incident angle of the predetermined light ray with respect to the specific flat surface, and n is a refractive index of the light guide.

6. the incidence surface is inclined with respect to a normal direction to the flat surface so as to be positioned toward the one side in the one direction toward the other side in the normal direction to the flat surface, an incident direction (Di) when the predetermined light ray is incident on the incident surface is inclined with respect to the normal direction of the flat surface such that a straight line parallel to the incident direction is located on the one side of the one direction toward the one side of the normal direction of the flat surface, The plurality of flat surfaces includes a specific flat surface (161a) on which the predetermined light ray reaches without being reflected from the incident surface, 5. The optical element of claim 4, wherein the light guide satisfies "θi<φ" and "ψ<φ", where φ is an incident angle of the specified light ray with respect to the specific flat surface, θi is an angle between the incident direction and a direction normal to the flat surface, and ψ is an angle between the incident surface and a direction normal to the flat surface.

7. The second surface has an incident side edge (251) located at an end on the other side of the second surface, the end being opposite to the one side in the one direction, The incident surface has a second end edge (152) located at the end of the incident surface on the other side in the normal direction of the flat surface, and is formed so as to expand from the one side to the other side in the normal direction of the flat surface with respect to the incident side edge, The plurality of flat surfaces includes a specific flat surface (161a) on which the predetermined light ray reaches without being reflected from the incident surface, 5. The optical element of claim 4, wherein in a light-guiding cross section perpendicular to each of the incident surface and the flat surface, an angle that a virtual line segment (LN2) connecting the incident side edge of the second surface and the other edge of the incident surface makes with respect to a normal direction of the flat surface is ξ, and an incident angle of the specified light ray with respect to the specific flat surface is φ.

8. The light guide is disposed in air, the predetermined light ray is reflected by the second surface inside the light guide once, the incidence surface is inclined with respect to a normal direction to the flat surface so as to be positioned toward the one side in the one direction toward the other side in the normal direction to the flat surface, an incident direction (Di) when the predetermined light ray is incident on the incident surface is inclined with respect to the normal direction of the flat surface such that a straight line parallel to the incident direction is located on the one side of the one direction toward the one side of the normal direction of the flat surface, In a light guide cross section perpendicular to each of the incident surface and the flat surface, a specific flat surface (161a) among the plurality of flat surfaces where the specific light ray reaches without being reflected from the incident surface reflects the specific light ray, and an intersection point (PB) where the specific light ray that has been reflected on the specific flat surface and then reaches the specific exit surface intersects with the specific exit surface is defined as H, and an eye point located on the one side of the normal direction of the flat surface with respect to the light guide and on the virtual straight line is defined as H.

5. The optical element according to claim 4, wherein the relationship "ζ=1 / 2×[arccos{cos(θi+ψ+arcsin(H×cosθi / D)) / n}+arcsin{cos(ψ+θi) / n}-π / 2]" is established, where D is a distance between an incident surface (EP) and the external scene point, ζ is an angle at which the second surface is inclined with respect to the one direction, θi is an angle between the incident surface and the normal direction to the flat surface, ψ is an angle between the incident surface and the normal direction to the flat surface, and n is a refractive index of the light guide.

9. The second surface has an incident side edge (251) located at an end on the other side of the second surface, the end being opposite to the one side in the one direction, The plurality of flat surfaces includes a specific flat surface (161a) on which the predetermined light ray reaches without being reflected from the incident surface, 5. The optical element of claim 4, wherein in a light guiding cross section perpendicular to each of the incident surface and the flat surface, an incident angle of the specified light ray with respect to the specified flat surface is φ, the number of times the specified light ray is reflected to the second surface inside the light guiding body is m, a distance along a normal direction of the flat surface between the incident side edge and the flat surface is T, and a width occupied by the second surface in the one direction is Wx, the light guiding body satisfies "Wx≧m×2×T×tanφ".

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