Optical member

Abstract

To provide an optical member which can guide incident light from an entrance surface by total reflection, and reduce the occurrence of moire due to a relation between reflectance of a prescribed pattern at an exit section and a pattern structure of the exit section.SOLUTION: A light guide 2 comprises: an entrance surface 2a where external light is incident; an exit section 2b emitting a part of the incident light from the entrance surface 2a to the outside; and a smooth surface 2c facing the exit section 2b. The light guide is composed of a light-transmissive material. The exit section 2b includes: a first region 2ba adjacent to the entrance surface 2a; and a second region 2bb adjacent to the first region 2ba. In the first region 2ba, a plurality of step-shaped reflective surfaces 4 in which a plurality of flat surfaces 41-43 facing a surface formed by the smooth surface 2c are arranged at different heights and separated from one another by a step portion 5, and a plurality of protruding prism parts 3 are alternately arrayed repeatedly. The flat surfaces 41-43 and the smooth surface 2c reflect a part of the incident light having entered into the light guide 2 from the entrance surface 2a, by total reflection.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, this type of optical member is, for example, attached to a light blocking body, and serves as a blind spot assistance device that allows external light from a blind spot area generated by the light blocking body to enter the inside, reflects the external light inside, and emits the external light from a surface different from the incident surface of the external light, thereby allowing the blind spot area to be viewed. For example, an optical member such as that described in Patent Document 1 can be cited.

[0003] The optical member described in Patent Document 1 is composed of a translucent light guide, and a part of the external light incident on the entrance surface of the light guide is guided by total reflection inside and is emitted to the outside from an exit part different from the entrance surface, allowing a user standing on the exit surface side to see the outside 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 part side, and reduces loss of external light due to absorption by the light guide inside the light guide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-028532 A Summary of the Invention [Problem to be solved by the invention]

[0005] The optical member described in Patent Document 1 has an exit portion having a plurality of protruding prism portions and a plurality of flat portions that emit light to the outside, and the prism portions and the flat portions are arranged alternately and repeatedly along the direction connecting the entrance surface and the terminal surface. In this optical member, the exit portion has a pattern structure of prism portions and flat portions, and incident light that reaches the exit portion generates reflected light according to the pattern of the flat portions.

[0006] As a result of extensive research by the inventors into this optical component, they have newly discovered that light reflected in a predetermined pattern by the emission section is guided by total reflection inside the light guide, and the spacing of the pattern changes when it reaches the emission section again, which can result in moire patterns due to the relationship with the structural pattern of the emission section.

[0007] In view of the above, an object of the present disclosure is to provide an optical element which is composed of a light guide capable of guiding incident light from an entrance surface by total reflection, and which is capable of suppressing the occurrence of moire due to the relationship between reflected light of a predetermined pattern at the exit portion and the pattern structure of the exit portion. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, the optical member is an optical member that internally reflects and guides external scene light (L1), and includes an incident surface (2a) on which the external scene light is incident, an emission portion (2b) that emits a portion of the light incident from the incident surface to the outside, a smooth surface (2c) facing the emission portion, and an end surface (2e) located on the opposite side to the incident surface and connecting the emission portion and the smooth surface, and includes a light guide (2) made of a light-transmitting material, and the emission portion has a first region (2ba) adjacent to the incident surface and a second region (2bb) adjacent to the first region, and the first region has different regions separated by a step portion (5, 51, 52). the first region has a plurality of stepped reflective surfaces (4) located at a height above the incident surface and having a plurality of flat surfaces (41-43) facing the smooth surface, and a plurality of protruding prism portions (3), with the stepped reflective surfaces and the prism portions arranged in an alternating manner; the second region has a plurality of prism portions and a plurality of flat portions (6) which are one flat surface, with the prism portions and the flat portions arranged in an alternating manner; the flat surface, the flat portions and the smooth surface reflect by total reflection a portion of the incident light (L2) that has entered the inside of the light guide from the incident surface, and the prism portion has an exit surface (3a) which emits a portion of the incident light to the outside.

[0009] In this optical member, light incident from the entrance surface is incident on a stepped reflective surface arranged in a first region of the exit section, is divided by the multiple flat surfaces that make up the stepped reflective surface, is reflected by total reflection, and is guided to a second region of the exit section. As a result, in this optical member, the pitch interval of the reflected light that reaches the second region is significantly different from the pattern interval between the prism portions and the flat portions in the second region, making it possible to reduce the occurrence of moire in the second region.

[0010] According to another aspect of the present disclosure, the optical member is an optical member that internally reflects and guides external scene light (L1), and includes an incident surface (2a) on which the external scene light is incident, an emission portion (2b) that has a plurality of protruding prism portions (3) and a plurality of flat portions (6) that are flat surfaces, and that emits a portion of the light incident from the incident surface to the outside, a smooth surface (2c) facing the emission portion, and a terminal surface (2e) located on the opposite side to the incident surface and connecting the emission portion and the smooth surface, and includes a light guide (2) made of a light-transmitting material, and a terminal surface (2e) located in the vicinity of the emission portion inside the light guide, the terminal surface (2e) being at least The light guide is provided with a plurality of refractive index difference layers (7) having a lower refractive index than the light guide, the plurality of flat surfaces (71-73) facing the plane formed by the smooth surface and arranged in an area where the incident light (L2) entering from the incident surface is directly incident, the plurality of flat surfaces (71-73) facing the plane formed by the smooth surface, the flat surfaces, the flat portions and the smooth surfaces reflect a portion of the incident light by total reflection, the prism portion has an exit surface (3a) which emits a portion of the incident light to the outside, and the plurality of refractive index difference layers are arranged at a distance from each other so as not to block the light of the incident light that enters the exit surface.

[0011] In this optical member, the light incident from the incident surface is incident on the refractive index difference layer arranged in a predetermined region near the exit portion where the light is directly incident, and is divided and reflected by the multiple flat surfaces constituting the refractive index difference layer by total reflection, and is guided to a region of the exit portion where the refractive index difference layer is not arranged. As a result, in this optical member, the pitch interval of the reflected light that reaches the region of the exit portion where there is no refractive index difference layer is significantly different from the pattern interval between the prism portion and the flat portion in that region, and the occurrence of moire in that region can be reduced.

[0012] According to another aspect of the present disclosure, the optical member is an optical member that internally reflects and guides external scene light (L1), and includes an entrance surface (2a) on which the external scene light is incident, a plurality of protruding prism portions (3) and a plurality of flat portions (6) that are flat surfaces, an exit portion (2b) that emits a portion of the light incident from the entrance surface to the outside, a divided reflection portion (2f) and a smooth surface (2c) that face the exit portion, and a terminal surface (2e) that is located on the opposite side to the entrance surface and connects the exit portion and the smooth surface, and is made of a light-transmitting material. The light guide (2) includes a light guide plate (3) having a plurality of stepped portions (3a) arranged in a row, the divided reflection portion being adjacent to the smooth surface and located closer to the incident surface than the smooth surface, and the divided reflection portion being formed by a plurality of flat portions and a plurality of reflective surfaces (11-13) facing the surface formed by the flat portions and located at different heights separated by step portions (14). The reflective surfaces, the flat portions and the smooth surfaces reflect a portion of the incident light (L2) that has entered the light guide from the incident surface by total reflection, and the prism portion has an exit surface (3a) that emits a portion of the incident light to the outside.

[0013] In this optical member, the light reflected from the region of the exit section where the light from the incident surface is directly incident is incident on the split reflector formed in the region where the light reaches, split by the multiple reflecting surfaces that make up the split reflector and reflected by total reflection, and is guided to the next region of the exit section. As a result, in this optical member, the pitch interval of the reflected light that reaches the next region of the exit section is significantly different from the pattern interval between the prism portion and the flat portion in the next region, making it possible to reduce the occurrence of moire in the next region.

[0014] 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]

[0015] [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]2 is an enlarged view of region III in FIG. 1, illustrating light guiding in a first region of the emission section. [Figure 4] FIG. 4 corresponds to FIG. 3 and is an explanatory diagram of the pitch interval of the prism portions in the first region of the emission portion, the pitch interval of the reflected light, and the step of the step portion. [Diagram 5] 11A and 11B are explanatory diagrams of light guiding in an optical member of a comparative example that does not have a stepped flat portion. [Figure 6] 6 is an explanatory diagram of the occurrence of moire in the optical member of the comparative example of FIG. 5. [Figure 7] FIG. 6 is a cross-sectional view showing an optical member according to a second embodiment. [Figure 8] 8 is an explanatory diagram of light guide in the optical member of FIG. 7. [Figure 9] 8 is an enlarged view of region IX in FIG. 7, illustrating light guiding in a first region of the emission section. [Figure 10] FIG. 10 corresponds to FIG. 9 and is an explanatory diagram of the pitch of the refractive index difference layer in the first region of the emission section, the pitch of the reflected light, and the step of the step section. [Figure 11] FIG. 11 is a cross-sectional view showing a modified example of the optical member of the second embodiment. [Figure 12] FIG. 11 is a cross-sectional view showing an optical member according to a third embodiment. [Figure 13] 13 is an explanatory diagram of light guide in the optical member of FIG. 12. [Figure 14] 13 is an enlarged view of region XIV in FIG. 12, illustrating light guiding in a first region of the emission section. [Figure 15] FIG. 15 corresponds to FIG. 14 and is an explanatory diagram of the pitch of the refractive index difference layer in the first region of the emission section, the pitch of the reflected light, and the step of the step section. [Figure 16] FIG. 13 is a cross-sectional view showing an optical member according to a fourth embodiment. [Figure 17] 17 is an explanatory diagram of light guide in the optical member of FIG. 16. [Figure 18] FIG. 17 is an enlarged view of region XVIII in FIG. 16, illustrating light guiding on a stepped reflecting surface. [Figure 19]FIG. 19 corresponds to FIG. 18 and is an explanatory diagram of the width of the stepped reflecting surface, the step height of the step portion, and the inclination angle. [Figure 20] FIG. 11 is a cross-sectional view showing an optical member according to another embodiment. [Figure 21] FIG. 21 is an enlarged cross-sectional view of region XXI in FIG. 20. [Figure 22] FIG. 11 is a cross-sectional view showing an optical member according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 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.

[0017] (First embodiment) An optical member 1 according to a first embodiment will be described with reference to the drawings.

[0018] [Basic configuration] The optical member 1 of the present embodiment can be used as a blind spot assistance device that is attached to, for example, a member or obstacle that blocks 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 predetermined light blocking body such as 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.

[0019] As shown in FIG. 1, an optical member 1 of this embodiment is made up of a light guide 2 having an entrance surface 2a, an exit portion 2b, a smooth surface 2c, an inclined surface 2d, and a terminal surface 2e.

[0020] For convenience of explanation, as shown in FIG. 1, the direction along the normal direction to the flat portion 6 or the smooth surface 2c of the optical member 1, which will be described later, and connecting the opposing exit portion 2b and smooth surface 2c, will be referred to as the "thickness direction D1". Also, the direction perpendicular to the thickness direction D1, which is the direction from the incident surface 2a toward the terminal surface 2e, that is, the direction in which the light incident from the incident surface 2a is guided, will be referred to as the "light guide direction D2". The light guide direction D2 is the direction along which the multiple prism portions 3 and flat portions 6, which will be described later, are repeatedly arranged, and is perpendicular to the extension direction of the prism portions 3 and flat portions 6, and may also be referred to as the arrangement direction.

[0021] 2, the optical member 1 is configured such that a part of the light incident from the incident surface 2a of the light guide 2 into the inside is reflected by the 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. For example, the optical member 1 guides external light from the incident surface 2a inside the light guide 2 and emits it to the outside from the exit portion 2b, thereby allowing a user on the exit portion 2b side to view the outside view in the blind spot area caused by the light blocking body.

[0022] 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, of the emitted light L3, the light emitted from a first region 2ba (described later) of the emission section 2b is referred to as a "first emitted light L31," the light emitted from the second region 2bb is referred to as a "second emitted light L32," and the light emitted from the third region 2bc is referred to as a "third emitted light L33."

[0023] 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 by a known resin molding method using a mold or the like (not shown). The light guide 2 is configured such that a part of the incident light L2 from the incident surface 2a is incident on the prism portion 3 of the exit portion 2b, and the remaining part of the incident light L2 is reflected by the flat surfaces 41 to 43 or the flat portion 6 described later, and this reflected light is directed toward the smooth surface 2c. The light guide 2 is designed such that the incident light L2 reflected by the flat surfaces 41 to 43 or the flat portion 6 is totally reflected by the smooth surface 2c or the flat portion 6, and is guided inside. Specifically, the light guide 2 is designed to satisfy the following formula (1) when the refractive index of its constituent material is n0, the incident angle of incident light L2 with respect to the smooth surface 2c, the flat surfaces 41-43, and the flat portion 6 is φ, and the external medium of the light guide 2 is an air layer with a refractive index of 1. The incident angle φ is the angle between the direction in which incident light L2 incident on the flat surfaces 41-43, the flat portion 6, or the smooth surface 2c travels and the thickness direction D1, and may also be referred to as the light guide angle φ.

[0024] sinφ>1 / n0 (1) As a result, even though the light guide 2 does not have a half mirror or mirror made of a reflective material different from the light guide 2, a portion of the incident light L2 is repeatedly reflected between the flat portion 6 and the smooth surface 2c, and the incident light L2 is emitted to the outside from the exit surface 3a of the prism portion 3, which will be described later.

[0025] The incident surface 2a is a surface that allows the external light L1 to enter the inside. The incident surface 2a is adjacent to the exit portion 2b and extends in a direction intersecting the exit portion 2b and the smooth surface 2c. For example, the incident surface 2a is inclined so as to approach the terminal surface 2e as it approaches the smooth surface 2c side, and is a flat surface inclined at an inclination angle ψ, which is an angle with the thickness direction D1. The inclination angle ψ of the incident surface 2a is smaller than the light guide angle φ. At this time, if the angle of the external light L1 with respect to the thickness direction D1 is θ, and ψ<π / 2-φ according to the refraction condition, the incident light L2 is refracted in a direction in which the light guide angle φ is larger than the angle θ of the external light L1, and is guided to a wider range of the exit portion 2b. The angle θ can also be said to be the incident angle of the external light L1 with respect to the light guide body 2. In the light guide 2, for example, φ is the total reflection angle, and since the refractive index of a typical light-transmitting resin material is 1.4 or more, n0·sinφ>1 gives φ>45.3, so that the light guide 2 has a structure that satisfies φ>ψ.

[0026] The exit portion 2b is formed adjacent to and intersecting with the incident surface 2a, and includes, for example, a first region 2ba, a second region 2bb, and a third region 2bc, which have different configurations. The exit portion 2b reflects a part of the incident light L2 toward the smooth surface 2c, and emits a part of the incident light L2 to the outside, so to speak, as a reflective exit surface.

[0027] The first region 2ba has, for example, a plurality of prism portions 3 which are triangular protrusions in a cross-sectional view, and a plurality of stepped reflecting surfaces 4 arranged between the prism portions 3, which are alternately arranged from the incident surface 2a toward the terminal surface 2e. The first region 2ba is a region into which the incident light L2 from the incident surface 2a is directly incident, that is, a region into which the incident light L2 from the incident surface 2a is incident without being reflected even once.

[0028] The prism parts 3 are protrusions that protrude from the step-like reflecting surface 4, and are arranged in parallel, for example, and in this embodiment, the height in the thickness direction D1 and the width in the light guide direction D2 are approximately the same. In this specification, "approximately the same" includes the case where they are completely the same, as well as the case where they are almost the same with a slight difference due to unavoidable factors such as processing errors. As shown in FIG. 3, 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 another 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 incident light L2 that reaches the exit surface 3a is emitted to the outside as the exit light L3 at the same angle θ as the outside scene light L1. Therefore, continuity is ensured between the outside view not passing through the optical member 1 and the outside view in the blind spot area that is made visible by the optical member 1, as viewed from a user positioned on the emission section 2b side. For example, the pitch interval between adjacent prism sections 3 in the light guiding direction D2 differs in the first region 2ba, the second region 2bb, and the third region 2bc. Hereinafter, the pitch interval between adjacent prism sections 3 in the light guiding direction D2 is referred to as the "prism pitch." For example, the prism pitch is constant in each of the regions 2ba to 2bc.

[0029] The stepped reflecting surface 4 includes, for example, a first flat surface 41, a second flat surface 42, and a third flat surface 43 that are flat surfaces substantially parallel to the smooth surface 2c, and a step portion 5 disposed between them. In this specification, "substantially parallel" includes not only a case where the surfaces are completely parallel, but also a case where the surfaces are almost parallel with a slight difference that is unavoidable due to processing errors and the like.

[0030] Hereinafter, for convenience, the step portion 5 connecting the first flat surface 41 and the second flat surface 42 will be referred to as the "first step portion 51," and the step portion 5 connecting the second flat surface 42 and the third flat surface 43 will be referred to as the "second step portion 52."

[0031] The stepped reflecting surface 4 is, for example, arranged in the order of a first flat surface 41, a first step portion 51, a second flat surface 42, a second step portion 52, and a third flat surface 43 from the incident surface 2a side. The flat surfaces 41 to 43 of the stepped reflecting surface 4 function as reflecting surfaces that reflect the incident light L2. For example, the flat surfaces 41 to 43 of the stepped reflecting surface 4 are located at different positions in the thickness direction D1, and the flat surface closer to the prism portion 3 on the terminal surface 2e side is located farther from the light guide body 2. The prism portion 3 on the terminal surface 2e side refers to the one of the two prism portions 3 adjacent to the stepped reflecting surface 4 that is located on the terminal surface 2e side.

[0032] For ease of explanation, the position in the thickness direction D1 will be referred to as the "height position", the direction along the thickness direction D1 from the emission portion 2b to the smooth surface 2c will be referred to as the "upper", and the direction from the smooth surface 2c to the emission portion 2b will be referred to as the "lower".

[0033] The stepped reflecting surface 4 has a stepped configuration in which, for example, the height position of the first flat surface 41 is substantially the same as that of the flat portion 6, and the height positions of the first flat surface 41, the second flat surface 42, and the third flat surface 43 are gradually lower in this order. The stepped reflecting surface 4 is provided in order to suppress the occurrence of moire caused by the difference between the pitch interval of the reflected light that reflects the incident light L2 and the structural pitch of the prism portion 3 and the flat portion 6 of the second region 2bb when the reflected light reaches the second region 2bb. The details of this will be described later.

[0034] The second region 2bb has, for example, a plurality of prism parts 3 and a plurality of flat parts 6, which are alternately arranged from the incident surface 2a toward the terminal surface 2e. The plurality of flat parts 6 are, for example, flat surfaces facing the smooth surface 2c and arranged substantially parallel to the smooth surface 2c. The plurality of flat parts 6 are, for example, arranged on the same plane. Since the incident light L2 from the incident surface 2a is incident at an angle equal to or greater than the critical angle, the plurality of flat parts 6 function as a reflecting surface that reflects the incident light L2 toward the smooth surface 2c by total reflection. For example, the prism pitch in the first region 2ba is PP1, and the prism pitch in the second region 2bb is PP2, which is smaller than PP1. In other words, the width in the light guide direction D2 of the portion reflecting the incident light L2 between the adjacent prism parts 3 in the second region 2bb is smaller than that in the first region 2ba.

[0035] The third region 2bc is composed only of a plurality of prism portions 3, which are repeatedly arranged along the light guide direction D2. The third region 2bc does not have a portion that reflects the incident light L2 toward the smooth surface 2c, and serves as an emission region that emits the incident light L2 that reaches the third region 2bc to the outside.

[0036] The emission section 2b is composed of the regions 2ba to 2bc having different ratios between the reflection width in the light guide direction D2 of the incident light L2 and the width of the portion emitting to the outside in the same direction, as described above, so that the light quantities of the emitted lights L31 to L33 can be made substantially uniform. Here, "substantially uniform" includes cases where the light quantities are almost the same, with slight differences due to unavoidable factors such as processing errors, in addition to cases where the light quantities are completely the same. Note that in this specification, a case where the number of regions constituting the emission section 2b is three will be described as a representative example, but this is not limiting, and the number of regions can be changed as appropriate.

[0037] The inclined surface 2d is a surface connecting the incident surface 2a and the smooth surface 2c, and is inclined at an inclination angle ξ with respect to the thickness direction D1 so that the closer it is to the smooth surface 2c, the closer it is to the terminal surface 2e, and is a surface that protrudes from the smooth surface 2c. In other words, the incident surface 2a and the inclined surface 2d form one large protruding prism portion in a cross-sectional view. That is, the light guide 2 is configured such that the height 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 flat portion 6 of the exit portion 2b to the smooth surface 2c. This allows the light guide 2 to widen the area of ​​the exit portion 2b where the incident light L2 from the incident surface 2a first arrives.

[0038] 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.

[0039] In addition, the side surfaces of the light guide 2, which are located at both ends in a direction perpendicular to the plane formed by the thickness direction D1 and the light guide direction D2 and connect the entrance surface 2a, the exit surface 2b, the smooth surface 2c, the inclined surface 2d and the terminal surface 2e, are surfaces that do not contribute optically, and their shapes, configurations, etc. are arbitrary.

[0040] The basic configuration of the optical member 1 has been described above.

[0041] [Step-like reflective surface] Next, the details and effects of the stepped reflecting surface 4 will be described with reference to the drawings.

[0042] In Figures 3 to 5, in order to make it easier to understand the light guide in the optical member 1 and the optical member of the comparative example described later, cross sections are not shown, but the light that has entered the optical member is hatched and the traveling directions of the incident light L2 and its reflected light are indicated by white arrows.

[0043] 3, the stepped reflecting surface 4 reflects the incident light L2 incident on three flat surfaces 41-43 arranged with a step portion 5 between them. In other words, the stepped reflecting surface 4 divides and reflects the incident light L2 on the multiple flat surfaces, making the pitch of the reflected light equal to or less than half the prism pitch PP1.

[0044] For ease of explanation, the incident light L2 reflected by the first flat surface 41 will be referred to as the "first reflected light L21," the light reflected by the second flat surface 42 as the "second reflected light L22," and the light reflected by the third flat surface 43 as the "third reflected light L23."

[0045] In the stepped reflecting surface 4, for example, the first step portion 51 and the second step portion 52 are flat inclined surfaces, and the inclination angles of the inclined surfaces with respect to the thickness direction D1 are substantially the same. The step portions 51 and 52 preferably have an inclination angle η with respect to the thickness direction D1 that is equal to or less than the light guide angle φ of the incident light L2, i.e., η≦φ. This allows the incident light L2 with the light guide angle φ to reach the second flat surface 42 and the third flat surface 43 without being blocked by the step portions 51 and 52, and prevents the loss of light while suppressing unintended reflection at the step portions 51 and 52.

[0046] In addition, the step portions 51, 52 are not limited to a planar shape as long as they do not obstruct the light L2 traveling toward the second flat surface 42 and the third flat surface 43, and can be any shape, such as a curved shape or a shape having both a planar portion and a curved portion.

[0047] The stepped reflecting surface 4 divides and reflects the incident light L2 by the flat surfaces 41-43, so that the pitch intervals P11-P13 of the reflected light L21-L23 are each equal to or less than half the prism pitch PP1. Here, the pitch interval P11 is the pitch of the first reflected light L21 and the second reflected light L22 in the light guide direction D2, as shown in FIG. 4, for example. The pitch interval P12 is the pitch of the second reflected light L22 and the third reflected light L23 in the light guide direction D2. The pitch interval P13 is the pitch of the third reflected light L23 and the first reflected light L21 in the other stepped reflecting surface 4 adjacent to the third flat surface 43 that produces the third reflected light L23 in the light guide direction D2. The stepped reflecting surface 4 splits the incident light L2 into reflected lights L21 to L23 having pitch intervals P11 to P13 that are significantly different from the prism pitch PP1, thereby suppressing the occurrence of moire in the second region 2bb.

[0048] Here, the occurrence of moire in an optical member of a comparative example that does not have a stepped reflecting surface 4, as shown in FIG. 5, will be described.

[0049] The optical member of the comparative example differs from the optical member 1 in that the exit portion is configured by alternately and repeatedly arranging a plurality of prism portions 100, which are triangular protrusions in a cross-sectional view, and a plurality of flat portions 101, which are flat surfaces, and the prism pitch of the prism portions 100 is constant over the entire area of ​​the exit portion. In other words, the optical member of the comparative example has the same structural pitch of the prism portions and flat portions in the exit portion over the entire area. The optical member of the comparative example totally reflects a portion of the incident light L2 by the flat portions 101 toward the smooth surface on the opposite side (not shown), and emits a portion of the incident light L2 to the outside from the exit surface 100a of the prism portions 100. The portion of the incident light L2 reflected by the flat portions 101 is referred to as reflected light Lr1, and the reflected light Lr1 is reflected at a pitch interval P Lr1 corresponds to the prism pitch PP0 of the prism portion 100.

[0050] This reflected light Lr1 is guided inside the optical member of the comparative example and reaches the exit portion again. However, since there is a distance to travel before it reaches the exit portion again, the pitch interval P Lr1In the emission section of the optical member of the comparative example, the region where the incident light L2 first arrives is defined as a first region, and the region where the incident light L2 reflected by the first region of the emission section arrives for the second time is defined as a second region. Lr1 is smaller in the second region than in the first region.

[0051] On the other hand, in the optical member of the comparative example, the prism pitch PP0 is constant throughout the entire area of ​​the exit portion, so that in the second region, the prism pitch PP0 and the pitch interval P Lr1 Therefore, in the optical member of the comparative example, as shown in Fig. 6, for example, a slight misalignment occurs between the light ray pattern of the reflected light in the second region and the structural pattern of the prism portion 100 and the flat portion 101, and moire may occur. When moire occurs, the visibility of the scene viewed at the exit portion decreases, so the optical member of the comparative example may decrease the visibility of the scene in the blind spot region.

[0052] In Fig. 6, the light and dark of the light beam pattern and the light and dark of the structure pattern are shown in black and white. In Fig. 6, the "light" of the light beam pattern and the structure pattern corresponds to the portion from which the emitted light L3 is emitted, and the "light" pattern is shown in white. In Fig. 6, the "dark" of the light beam pattern and the structure pattern corresponds to the portion from which the emitted light L3 is not emitted, and the "dark" pattern is shown in black. Fig. 6 is a diagram showing the light and dark pattern when viewed from the normal direction to the flat portion 101 of the emission portion.

[0053] Moire is a pattern with a pitch interval P of reflected light Lr1. Lr1 and the prism pitch PP0 is less than a certain value, and when this difference becomes large, the moire pattern becomes finer and less noticeable. Lr1 and the prism pitch PP0 are the same or are an integer multiple, moire will not occur. Therefore, in order to reduce moire, it is conceivable to make the prism pitch PP0 of the first region sufficiently smaller than that of the second region in the optical member of the comparative example.

[0054] In this case, however, the size of the prism portion 100 and therefore the area of ​​the exit surface 100a are reduced, and the emitted light L3 in the first region is more affected by diffraction due to the reduced area of ​​the exit surface 100a. Therefore, if the prism pitch PP0 in the first region is simply reduced, the moire can be reduced, but the scene viewed in the first region becomes more blurred, and the visibility of the scene in the blind spot region decreases.

[0055] In contrast, the optical member 1 of this embodiment is configured such that a plurality of stepped reflecting surfaces 4 are arranged in the first region 2ba of the exit portion 2b, and the incident light L2 is split into a plurality of reflected light beams L21-L23. As a result, the pitch intervals P11-P13 of the reflected light beams L21-L23 are significantly different from the prism pitch PP1, and as a result, the difference between the pitch intervals P11-P13 and the prism pitch PP2 when the reflected light beams reach the second region 2bb becomes large. As a result, the optical member 1 can suppress the occurrence of moire in the second region 2bb.

[0056] In addition, the optical member 1 has a stepped reflecting surface 4, and is configured such that the flatter surface closer to the terminal surface 2e is positioned lower in height, thereby ensuring a large area for the exit surface 3a of the prism portion 3. Therefore, the optical member 1 is less susceptible to the diffraction of the exit light L3 caused by the area of ​​the exit surface 3a, and can suppress a decrease in visibility of the scene viewed at the exit portion 2b.

[0057] 4, the widths of the reflected lights L21 to L23 in the light guide direction D2 are denoted by S11, S12, and S13, respectively, and the widths of the step portions 51 and 52 in the thickness direction D1 are denoted by D31 and D32. In this case, the pitch intervals P11 and P12 in the first region 2ba are expressed by the following equations (2) and (3).

[0058] P11=S11+2×D31×tanφ...(2) P12=S12+2×D32×tanφ...(3) In this specification, a case where the stepped reflecting surface 4 has three flat surfaces will be described as a representative example, but the present invention is not limited thereto. The number of steps is m (m: an integer of 2 or more), the number of flat surfaces is m+1, and m can be changed as appropriate. For example, the reflected light at the m-th flat surface 4m, which is the m-th surface counted from the incident surface 2a side of the stepped reflecting surface 4, is the m-th reflected light L2m, and the reflected light at the (m+1)th flat surface 4(m+1) is the (m+1)th reflected light L2(m+1). The widths of the m-th reflected light L2m and the (m+1)th reflected light L2(m+1) in the light guide direction D2 are S1m and S1(m+1), respectively, and the width of the m-th step portion 5m, which is the m-th surface counted from the incident surface 2a side, in the thickness direction D1 is D3m. At this time, the pitch interval P1m between the m-th reflected light L2m and the (m+1)-th reflected light L2(m+1) in the first region 2ba is expressed by the following formula (4).

[0059] P1m=S1m+2×D3m×tanφ...(4) From the viewpoint of reducing moire, the pitch intervals P11 to P1m need only be half or less of the prism pitch PP1, and do not need to be approximately the same, but when they are approximately the same, the effect of making the amount of light of the emitted light L3 approximately uniform is obtained. This is because, when the pitch intervals P11 to P1m are approximately the same, the first reflected light L21 to the m-th reflected light L2m toward the second region 2bb are approximately equidistant, i.e., the amount of light is approximately the same, and the variation in the amount of light emitted from the second region 2bb and the third region 2bc is reduced. When the pitch intervals P11 to P1m are approximately the same, the stepped reflecting surface 4 has, for example, approximately the same widths D31 to D3m of the first step portion 51 to the m-th step portion 5m, and approximately the same widths S11 to S1(m+1) of the first flat surface 41 to the (m+1)th flat surface 4(m+1).

[0060] In addition, since the step portion 5 of the stepped reflecting surface 4 and the other surface 3b of the prism portion 3 are surfaces that do not contribute optically, they may be covered with a light-shielding film (not shown) to prevent external light from the exit portion 2b side from entering the inside of the light guide 2.

[0061] According to this embodiment, the first region 2ba of the emission part 2b, into which the incident light L2 from the incident surface 2a is directly incident, is an optical member 1 in which the prism portions 3 and the stepped reflecting surfaces 4 are alternately arranged, and a part of the incident light L2 is divided and reflected by a plurality of flat surfaces 41-43. In this optical member 1, a part of the incident light L2 is divided into a plurality of reflected lights L21-L23, and the pitch intervals P11-P13 of the reflected lights L21-L23 are significantly different from the prism pitch PP1 of the prism portion 3. Therefore, in the optical member 1, the pitch intervals P11-P13 of the reflected lights L21-L23 are significantly different from the prism pitch PP2 of the second region 2bb, making it possible to reduce moire.

[0062] (1) In this embodiment, the optical member 1 is configured such that, among the flat surfaces 41 to 43, the stepped reflective surface 4 is located lower in the thickness direction D1 as the flat surface is closer to the prism portion 3 on the terminal surface 2e side. This allows the optical member 1 to ensure that the area of ​​the exit surface 3a of the prism portion 3 is greater than or equal to a predetermined value, and reduces the diffraction effect of the exit light L3 in the first region 2ba. In other words, this optical member 1 can ensure visibility of the scene in the blind spot while reducing moiré caused by the periodic structure between the prism portion 3 and the reflective surface due to total reflection.

[0063] Second embodiment The optical member 1 of the second embodiment will be described with reference to FIGS.

[0064] In Figures 9 and 10, for the same purpose as in Figure 3, although they do not show cross sections, the incident light L2 and its reflected lights L21 to L23 in the optical element 1 are hatched, and the directions in which these lights travel are indicated by white arrows.

[0065] 7, the optical member 1 of this embodiment differs from the above-described first embodiment in that the configuration of the emission section 2b is changed and that a refractive index difference layer 7 is provided inside the light guide 2. In this embodiment, this difference will be mainly described.

[0066] In the present embodiment, the first region 2ba of the emission section 2b is formed by alternately and repeatedly arranging the prism portions 3 and the flat portions 6 in the same manner as the second region 2bb. In the first region 2ba, the prism pitch PP1 of the prism portions 3 is larger than the prism pitch PP2 of the second region 2bb. In the present embodiment, the first region 2ba is inside the light guide 2, and a refractive index difference layer 7 having a lower refractive index than the light guide 2 is formed near the flat portion 6 on the emission section 2b side. Among the multiple flat portions 6, those located in the first region 2ba do not need to function as a reflection surface inside, and therefore may be covered with a light shielding film (not shown) to prevent external light from the emission section 2b side from entering the inside.

[0067] 8, in the optical member 1, a part of the incident light L2 is reflected toward the smooth surface 2c by total reflection at the interface between the light guide 2 in the first region 2ba and the refractive index difference layer 7, and the remaining part passes through gaps in the refractive index difference layer 7 and is emitted to the outside from the emission surface 3a of the prism portion 3. The incident light L2 incident on the refractive index difference layer 7 is divided and reflected by flat surfaces 71 to 73 of the refractive index difference layer 7, which will be described later. The incident light L2 reflected by the refractive index difference layer 7 is totally reflected by the smooth surface 2c, as in the first embodiment, and is then guided to the second region 2bb or the third region 2bc and emitted to the outside from the prism portion 3.

[0068] The refractive index difference layer 7 is composed of, for example, a low refractive index material with a refractive index n1 (<n0) that is relatively lower than that of the light guide 2, or an air layer. Thereby, the refractive index difference layer 7 satisfies the total reflection condition of sinφ > n1 / n0 or sinφ > 1 / n0, and the incident light L2 incident on the flat surfaces 71 to 73 is reflected. As shown in, for example, FIG. 9, the refractive index difference layer 7 has a plurality of flat surfaces 71 to 73 substantially parallel to the smooth surface 2c and a stepped portion 8 connecting between the flat surfaces. For the refractive index difference layer 7, for example, the surface on the side opposite to the injection portion 2b is, in order from the incident surface 2a side, the first flat surface 71, the first stepped portion 81, the second flat surface 72, the second stepped portion 82, and the third flat surface 73. The refractive index difference layer 7 has, for example, a plurality of flat surfaces 71 to 73 with different height positions. From the viewpoint of ensuring the area of the emission surface 3a in the first region 2ba, it is preferable that the flat surface closer to the end surface 2e has a lower height position, that is, it is configured to approach the injection portion 2b.

[0069] In this embodiment, the light guide 2 can be manufactured by a resin molding method such as molding the portion from the smooth surface 2c side to the surfaces that will become the flat surfaces 71 to 73 and the stepped portions 81 and 82 of the refractive index difference layer 7 using a mold (not shown), and then molding the remaining portion using a different mold.

[0070] The first flat surface 71 is, for example, the flat surface with the highest height position among the plurality of flat surfaces of the refractive index difference layer 7, and is a reflection surface that reflects a part of the incident light L2 as the first reflected light L21 by total reflection. The second flat surface 72 is, for example, at a height position between the first flat surface 71 and the third flat surface 73, and is a reflection surface that reflects a part of the incident light L2 as the second reflected light L22 by total reflection. The third flat surface 73 is, for example, the flat surface with the lowest height position among the plurality of flat surfaces of the refractive index difference layer 7, and is a reflection surface that reflects a part of the incident light L2 as the third reflected light L23 by total reflection. The flat surfaces 71 to 73 are arranged with the stepped portion 8 therebetween in the light guiding direction D2, and serve to divide the incident light L2 into a plurality of parts and reflect them to the smooth surface 2c side.

[0071] The first step portion 81 and the second step portion 82 are, for example, planar in shape and have an inclined surface inclined at an inclination angle η with respect to the thickness direction D1. It is preferable that the inclination angle η is equal to or smaller than the light guide angle φ of the incident light L2, i.e., η≦φ, so as not to impede the incident light L2 from being incident on the second flat surface 72 and the third flat surface 73.

[0072] In addition, the shape and size of the portions of the refractive index difference layer 7 other than the flat surfaces 71 to 73 and the step portions 81 and 82 are arbitrary as long as they do not obstruct the light of the incident light L2 toward the exit surface 3a of the prism portion 3. The refractive index difference layer 7 is arranged so that, for example, the light guide angle of the incident light L2 is φ and the layer 7 does not pass through the exit surface 3a of the prism portion 3 and is not positioned on a virtual straight line having an angle of φ with respect to the thickness direction D1. The refractive index difference layer 7 is arranged at a position where the distance in the thickness direction D1 from the flat portion 6 is a predetermined value or less so as not to cause unintended reflection in the light guide 2 or to obstruct the reflected light L21 to L23 generated by other refractive index difference layers 7. In addition, the refractive index difference layer 7 is arranged so that, for example, the number of step portions is k (k is an integer of 1 or more) and the number of flat surfaces is k+1, and k is arbitrary.

[0073] 10, the pitch interval between the reflected lights L21 and L22 is P21, and the pitch interval between the reflected lights L22 and L23 is P22. The pitch interval between the third reflected light L23 and the first reflected light L21 of the refractive index difference layer 7 adjacent to the refractive index difference layer 7 that generates the third reflected light L23 is P23. In this case, the pitch intervals P21 to P23 are each set to half or less of P2, where P2 is the pitch interval between the adjacent refractive index difference layers 7 in the light guide direction D2. As a result, the optical member 1 is in a state where the pitch intervals P21 to P23 and the prism pitch PP2 when the reflected lights L21 to L23 reach the second region 2bb are significantly different from each other, and an effect of reducing moire is obtained.

[0074] Moreover, the widths of the reflected lights L21 to L23 in the light guide direction D2 are denoted by S21, S22, and S23, respectively, as shown in Fig. 9, and the widths of the step portions 81 and 82 in the thickness direction D1 are denoted by D41 and D42, respectively, as shown in Fig. 10. In this case, the pitch intervals P21 and P22 in the first region 2ba are expressed by the following equations (5) and (6).

[0075] P21=S21+2×D41×tanφ...(5) P22=S22+2×D42×tanφ...(6) It is not necessary for the pitch intervals P21 to P23 to be substantially the same, but if they are substantially the same, the effect of making the amount of emitted light L3 substantially uniform can be obtained.

[0076] The optical member 1 of this embodiment also provides the same effect as that of the first embodiment. The optical member 1 of this embodiment has a refractive index difference layer 7 inside the light guide 2, and the flat surfaces 71-73 of the refractive index difference layer 7 function as reflective surfaces in the first region 2ba, so that the flat portion 6 in the first region 2ba can be covered with a light-shielding film (not shown). Therefore, the optical member 1 of this embodiment also provides the effect of reducing the influence of the intrusion of external light from the emission portion 2b in the first region 2ba.

[0077] (Modification of the second embodiment) The optical member 1 may have a configuration in which the light guide 2 is composed of a base 21 and a prism sheet 22, which are bonded together with a transparent adhesive layer 23, as shown in FIG.

[0078] The base 21 has, for example, a part of the incident surface 2a, a smooth surface 2c, an inclined surface 2d, and a part of the end surface 2e, and a cavity 211 constituting the refractive index difference layer 7. The prism sheet 22 has, for example, the remaining part of the incident surface 2a, the exit part 2b, and the remaining part of the end surface 2e, and a flat surface part 221 facing the base 21, and the flat surface part 221 is bonded to the base 21 via a transparent adhesive layer 23. The base 21 and the prism sheet 22 are formed separately, for example, by any resin molding method using a mold not shown. The transparent adhesive layer 23 is made of an optical adhesive such as OCA or OCR, and has the same refractive index as the constituent materials of the base 21 and the prism sheet 22. Note that OCA and OCR are abbreviations of Optical Clear Adhesive and Optical Clear Resin, respectively. In this case, the refractive index difference layer 7 is formed, for example, of an air layer present in the hollow portion 211, but may be formed by filling the hollow portion 211 with a material having a lower refractive index than the base portion .

[0079] This modification also provides the optical member 1 with the same effects as those of the second embodiment. In addition, by forming the light guide 2 from a plurality of members, there is also an effect that the manufacture is easier.

[0080] Third embodiment The optical member 1 of the third embodiment will be described with reference to FIGS.

[0081] In Figures 14 and 15, for the same purpose as in Figure 3, although they do not show cross sections, the incident light L2 and its reflected lights L21 to L23 in the optical element 1 are hatched, and the directions in which these lights travel are indicated by white arrows.

[0082] 12, the optical member 1 of this embodiment differs from the above-described first embodiment in that a first region 2ba of an emission section 2b is formed by repeatedly arranging a plurality of protrusions 9 each having an emission surface 9a, and a refractive index difference layer 7 is formed in the protrusions 9 inside the light guide 2. This embodiment will mainly describe this difference. Also, since the configuration of the refractive index difference layer 7 is basically the same as in the above-described second embodiment, this embodiment will mainly describe the difference.

[0083] In this embodiment, the refractive index difference layer 7 is formed, for example, partially or entirely within the protrusion 9. The refractive index difference layer 7 has, for example, flat surfaces 71 to 73 and step portions 81 and 82, and is formed so that the first flat surface 71 is at the same height position as the flat portion 6 of the second region 2bb. The refractive index difference layer 7 is configured such that, for example, the flat surfaces among the flat surfaces 71 to 73 closer to the terminal surface 2e have lower height positions, that is, closer to the exit portion 2b. The refractive index difference layer 7 is disposed, for example, so as not to be located on a virtual straight line that passes through the exit surface 9a of the protrusion 9 and is inclined at an angle φ with respect to the thickness direction D1, with the light guide angle of the incident light L2 being φ.

[0084] 12, the protrusion 9 has a trapezoidal shape in a cross-sectional view, and an inclined surface located on the terminal surface 2e side serves as an exit surface 9a parallel to the entrance surface 2a. The multiple protrusions 9 are repeatedly arranged in the first region 2ba along the light guiding direction D2 and are arranged parallel to one another.

[0085] The multiple protrusions 9 have an emission surface 9a and may have any shape other than the emission surface 9a as long as they do not block the emission light L3 from the emission surface 9a of adjacent protrusions 9. The shape is not limited to a trapezoidal shape, and the shape of the portion other than the emission surface 9a may be arbitrary. In order to prevent external light from the emission portion 2b side from entering the light guide 2, the multiple protrusions 9 may have a portion other than the emission surface 9a covered with a light-shielding film (not shown).

[0086] In the present embodiment, as shown in, for example, Fig. 13 and Fig. 14, in the first region 2ba, a part of the incident light L2 from the incident surface 2a is split and reflected by the flat surfaces 71-73 of the refractive index difference layer 7, while the remaining part is emitted to the outside from the emission surface 9a of the protrusion 9. In the first region 2ba, a part of the incident light L2 is split by the flat surfaces 71-73 into a first reflected light L21, a second reflected light L22, and a third reflected light L23, and is reflected to the smooth surface 2c. In the second region 2bb and the third region 2bc, the optical member 1 reflects a part of the incident light L2 from the smooth surface 2c and the flat portion 6, and emits the remaining part from the prism portion 3 to the outside, as in the first embodiment.

[0087] In this embodiment, as shown in Fig. 15, the pitch intervals P21 to P23 in the light guide direction D2 of the reflected lights L21 to L23 do not have to be substantially the same as in the second embodiment. It is preferable that they are substantially the same from the viewpoint of substantially uniforming the amount of light of the emitted light L3 at the emission section 2b. In this case, the widths S21 to S23 in the light guide direction D2 of the reflected lights L21 to L23, the inclination angles η of the step portions 81 and 82, the widths D41 and D42 in the thickness direction D1, and the pitch interval P2 in the light guide direction D2 of the refractive index difference layer 7 are designed in the same manner as in the second embodiment.

[0088] The optical member 1 of this embodiment can achieve the same effects as those of the second embodiment. In addition, by providing a plurality of protrusions 9 that have a high degree of freedom in terms of shape and configuration in portions other than the exit surface 9a, it is expected to achieve an effect of reducing manufacturing costs compared to the second embodiment.

[0089] (Fourth embodiment) The optical member 1 of the fourth embodiment will be described with reference to FIGS.

[0090] In Figures 18 and 19, for the same purpose as in Figure 3, although they do not show cross sections, the incident light L2 and its reflected lights L21 to L23 in the optical element 1 are hatched, and the directions in which these lights travel are indicated by white arrows.

[0091] 16, the optical member 1 of this embodiment differs from the above-described first embodiment in that the first region 2ba of the emission portion 2b has a configuration similar to that of the second region 2bb, and has a divided reflecting portion 2f formed by a stepped reflecting surface 10 between the smooth surface 2c and the inclined surface 2d. In this embodiment, this difference will be mainly described.

[0092] In the present embodiment, the emission section 2b is configured in such a manner that the prism portions 3 and the flat portions 6 are alternately arranged in a repeated manner as in the second embodiment, and the prism pitch PP1 is larger than that of the second region 2bb. In the present embodiment, the first region 2ba is configured in such a manner that the flat portions 6 reflect a part of the incident light L2 to the splitting and reflecting portion 2f, and the prism portions 3 emit the remaining part of the incident light L2 to the outside, as shown in FIG.

[0093] The dividing reflector 2f is formed by repeatedly arranging a plurality of stepped reflecting surfaces 10 along the light guiding direction D2. As shown in Fig. 18, for example, the dividing reflector 2f divides the incident light L2 with a plurality of reflecting surfaces 11-13 of the stepped reflecting surface 10, and reflects the reflected light L21-L23 toward the second region 2bb of the emission section 2b. The width of the dividing reflector 2f in the light guiding direction D2 is equal to or smaller than the width of the first region 2ba in the same direction.

[0094] The stepped reflecting surface 10 includes, for example, a first reflecting surface 11, a second reflecting surface 12, and a third reflecting surface 13 that are substantially parallel to the flat portion 6, and a step portion 14 that connects the adjacent reflecting surfaces. The stepped reflecting surface 10 has the first reflecting surface 11, the second reflecting surface 12, and the third reflecting surface 13 that are at different height positions. The reflecting surfaces 11 to 13 are configured such that, for example, the closer to the terminal surface 2e, the higher the height position is, that is, the farther from the light guide 2. For example, the reflecting surfaces 11 to 13 are configured such that the first reflecting surface 11 is at the same height position as the smooth surface 2c, the second reflecting surface 12 protrudes from the first reflecting surface 11 and the smooth surface 2c, and the third reflecting surface 13 protrudes from the smooth surface 2c further than the second reflecting surface 12. 19, the inclination angle η of the planar step portions 14 of the stepped reflective surface 10 with respect to the thickness direction D1 is equal to or smaller than the light guide angle φ of the incident light L2. As a result, in the stepped reflective surface 10, a portion of the incident light L2 reflected from the first region 2ba is not blocked by the step portions 14, and is reflected efficiently by the first reflecting surface 11, the second reflecting surface 12, and the third reflecting surface 13, thereby suppressing loss of light.

[0095] In addition, the step portion 14 is not limited to a planar shape as long as it does not obstruct the light L2 traveling toward the second reflecting surface 12 and the third reflecting surface 13, and can be other shapes such as a curved shape or a composite shape having a planar portion and a curved portion.

[0096] 18, the reflected light from the reflecting surfaces 11 to 13 is respectively referred to as the first reflected light L21, the second reflected light L22, and the third reflected light L23, and the pitch intervals of the reflected light L21 to L23 in the light guide direction D2 are respectively referred to as P31, P32, and P33. Note that the pitch intervals P31 and P32 are respectively the pitch interval between the first reflected light L21 and the second reflected light L22, and the pitch interval between the second reflected light L22 and the third reflected light L23. Also, the pitch interval P33 is the pitch interval between the third reflected light L23 and the first reflected light L21 by the stepped reflecting surface 10 adjacent to the stepped reflecting surface 10 that produces the third reflected light L23.

[0097] At this time, the step-like reflecting surfaces 10 are configured so that the pitch interval P3 between the adjacent step-like reflecting surfaces 10 in the light guide direction D2 is P3, and the pitch intervals P31 to P33 are each equal to or less than half the pitch interval P3. The step-like reflecting surfaces 10 are provided with a pitch interval P3 that is equal to or less than the prism pitch PP1 in the first region 2ba and the same number as the number of flat portions 6 in the first region 2ba. As a result, in the optical member 1 of this embodiment, all of the incident light L2 reflected in the first region 2ba is incident on the divided reflecting portion 2f, and is divided into reflected light L21 to L23 with pitch intervals P31 to P33 that are significantly different from the prism pitch PP2 in the second region 2bb. For this reason, the optical member 1 is configured to reduce moire in the second region 2bb.

[0098] The pitch intervals P31 to P33 of the reflected lights L21 to L23 do not need to be approximately the same, but are preferably approximately the same from the viewpoint of uniforming the amount of the emitted light L3 at the emission section 2b. In this case, the widths S31 to S33 of the reflected lights L21 to L23 in the light guide direction D2, the inclination angle η of the step section 14, and the widths D51 and D52 in the thickness direction D1 are designed similarly to the second embodiment.

[0099] The optical member 1 of this embodiment also has the same effect as that of the first embodiment. In addition, since the optical member 1 does not have a step portion with an inclination angle η in the first region 2ba of the emission portion 2b, it is possible to suppress external light on the emission portion 2b side from entering the inside of the light guide 2, thereby obtaining the effect of reducing the occurrence of ghost images.

[0100] (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.

[0101] (1) The optical member 1 may have a modified arrangement and configuration of the incident surface 2a, for example, as shown in FIG. 20. Specifically, the incident surface 2a may be disposed adjacent to the smooth surface 2c and facing the exit portion 2b together with the smooth surface 2c. The optical member 1 has the incident surface 2a and the smooth surface 2c facing the exit portion 2b substantially parallel to each other, and further has an incident side surface 2g located on the opposite side of the terminal surface 2e and connecting the incident surface 2a and the exit portion 2b. In this case, the incident surface 2a protrudes from the smooth surface 2c, for example, and has a plurality of triangular protruding incident prism portions 15 in a cross-sectional view. The incident surface 2a is composed of only a plurality of incident prism portions 15, which are repeatedly arranged along the light guide direction D2. In addition, the incident side surface 2g may have any surface shape and inclination as long as it does not prevent the incident light L2 from the incident surface 2a from entering the exit portion 2b, and may be covered with a light-shielding film (not shown) to prevent unintended incidence of external light.

[0102] As shown in FIG. 21, the surface of the incident prism portion 15 opposite to the terminal end surface 2e is the incident portion 15a parallel to the exit surface 3a of the prism portion 3. The surface of the incident prism portion 15 adjacent to the incident portion 15a on the terminal end surface 2e side is the adjacent surface 15b having an inclination angle α with respect to the thickness direction D1. The incident prism portion 15 is designed such that, for example, the inclination angle of the outside scene light L1 incident on the incident portion 15a is θ, the inclination angle of the incident portion 15a with respect to the thickness direction D1 is ψ, and the inclination angle α of the adjacent surface 15b satisfies θ<α<ψ. This allows the outside scene light L1 to enter the incident portion 15a without being blocked by the adjacent surface 15b, and prevents the incident light L2 from being generated in gaps between the incident prism portions 15, resulting in an incident surface 2a that can reduce the loss of light rays.

[0103] The above-mentioned modified examples of the optical member 1 have been shown as examples applied to the first embodiment, but the present invention is not limited to this and can also be applied to embodiments other than the first embodiment and their modified examples.

[0104] (2) As shown in FIG. 22, the optical member 1 may have the same configuration as that of the second embodiment, and the arrangement of the plurality of refractive index difference layers 7 in the light guide 2 may be changed to the vicinity of the smooth surface 2c. In this case, the refractive index difference layer 7 is arranged in a predetermined region near the surface of the smooth surface 2c on the inclined surface 2d side, where the incident light L2 reflected by the first region 2ba is incident. The refractive index difference layer 7 is arranged, for example, in the order of the first flat surface 71, the second flat surface 72, and the third flat surface 73 from the incident surface 2a side toward the terminal surface 2e, so that the flat surface on the terminal surface 2e side is higher in height, that is, closer to the smooth surface 2c. In addition, the refractive index difference layer 7 may be arranged in a plurality of layers, or may be configured as one layer in which the first flat surface 71, the second flat surface 72, and the third flat surface 73 are repeatedly arranged in this order.

[0105] This modified example also provides the optical member 1 with a moire reduction effect, similar to the first embodiment. That is, the optical member 1 only needs to be configured to be able to split the incident light L2 into a plurality of reflected lights at a pitch interval significantly different from the prism pitch PP2 of the second region 2bb at any point between the first region 2ba and the second region 2bb of the emission part 2b.

[0106] (3) It goes without saying that in each of the above embodiments, the elements constituting the embodiment are not necessarily essential, except when expressly stated as essential or when it is clearly considered essential in principle. In addition, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when expressly stated as essential or when it is clearly limited to a specific number in principle. In addition, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., except when expressly stated as essential or when it is clearly limited to a specific shape, positional relationship, etc. in principle.

[0107] (In view of the present disclosure) The present disclosure described above can be understood from the following viewpoints, for example.

[0108] [First viewpoint] An optical member that internally reflects and guides external light (L1), The light guide (2) includes an incident surface (2a) into which the external scene light is incident, an exit portion (2b) that emits a portion of the light incident from the incident surface to the outside, a smooth surface (2c) that faces the exit portion, and a terminal surface (2e) that is located on the opposite side to the incident surface and connects the exit portion and the smooth surface, and is made of a light-transmitting material; the emission section has a first region (2ba) adjacent to the incident surface and a second region (2bb) adjacent to the first region, the first region has a plurality of stepped reflective surfaces (4) each having a plurality of flat surfaces (41-43) facing the smooth surface and located at different heights with step portions (5, 51, 52) in between, and a plurality of protruding prism portions (3), the stepped reflective surfaces and the prism portions being alternately and repeatedly arranged; The second region has a plurality of the prism portions and a plurality of flat portions (6) which are one flat surface, and the prism portions and the flat portions are arranged alternately and repeatedly, The flat surface, the flat portion, and the smooth surface reflect a part of the incident light (L2) that has entered the inside of the light guide from the incident surface by total reflection, The prism portion is an optical member having an exit surface (3a) that emits a part of the incident light to the outside.

[0109] [Second viewpoint] A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the smooth surface toward the flat portion in the thickness direction is defined as down, and positions of the flat surfaces in the thickness direction are defined as height positions, The optical member according to a first aspect, wherein the stepped reflective surface has a lower height position than the flat surfaces closer to the end surface among the plurality of flat surfaces.

[0110] [Third Perspective] On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), The optical member according to the first or second aspect, wherein the first region has a width (S11 to S13) of each of the plurality of flat surfaces in the light guiding direction that is equal to or less than half the pitch interval (PP1) between adjacent prism portions.

[0111] [Fourth viewpoint] An optical member that internally reflects and guides external light (L1), a light guide (2) made of a light-transmitting material, the light guide (2) having 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 a plurality of flat portions (6) that are flat surfaces and which emits a portion of the light incident from the incident surface to the outside, a smooth surface (2c) facing the exit portion, and a terminal surface (2e) located on the opposite side to the incident surface and connecting the exit portion and the smooth surface; a plurality of refractive index difference layers (7) that are disposed in the vicinity of the emission portion inside the light guide, in a region where at least the incident light (L2) entering from the incident surface is directly incident, that are disposed at different heights via step portions (8, 81, 82), that have a plurality of flat surfaces (71-73) opposed to a plane formed by the smooth surface, and that have a refractive index lower than that of the light guide; the flat surface, the flat portion, and the smooth surface reflect a portion of the incident light by total reflection; The prism portion has an exit surface (3a) that emits a part of the incident light to the outside, The plurality of refractive index difference layers are arranged at a distance from each other so as not to block light that is incident on the exit surface out of the incident light.

[0112] [Fifth viewpoint] A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the smooth surface toward the flat portion in the thickness direction is defined as down, and positions of the flat surfaces in the thickness direction are defined as height positions, The optical member according to a fourth aspect, wherein the refractive index difference layer has a lower height position for a flat surface among the plurality of flat surfaces that is closer to the terminal surface.

[0113] [Sixth viewpoint] On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), The optical member according to the fourth or fifth aspect, wherein the width (S21 to S23) of each of the flat surfaces in the light guide direction of the refractive index difference layer is equal to or less than half the pitch interval (P2) between adjacent refractive index difference layers.

[0114] [Seventh viewpoint] The optical member according to any one of the fourth to sixth aspects, wherein the refractive index difference layer is an air layer.

[0115] [Eighth viewpoint] An optical member that internally reflects and guides external light (L1), The light guide (2) is made of a light-transmitting material and includes an incident surface (2a) on which the external scene light is incident, an emission section (2b) having a plurality of protruding prism sections (3) and a plurality of flat sections (6) that are flat surfaces and emits a portion of the light incident from the incident surface to the outside, a dividing reflection section (2f) and a smooth surface (2c) that face the emission section, and a terminal surface (2e) that is located on the opposite side to the incident surface and connects the emission section and the smooth surface, The splitting reflection section is adjacent to the smooth surface, is located closer to the incident surface than the smooth surface, and is formed by repeatedly arranging a plurality of stepped reflection surfaces (10) in which a plurality of reflection surfaces (11 to 13) facing the surface formed by the plurality of flat portions are located at different heights with step portions (14) between them, The reflecting surface, the flat portion, and the smooth surface reflect, by total reflection, a portion of the incident light (L2) that has entered the inside of the light guide from the incident surface, The prism portion is an optical member having an exit surface (3a) that emits a part of the incident light to the outside.

[0116] [Ninth viewpoint] A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the flat portion toward the smooth portion in the thickness direction is defined as an up direction, and positions of the plurality of reflecting surfaces in the thickness direction are defined as height positions, The optical member according to an eighth aspect, wherein the stepped reflecting surface is such that the reflecting surfaces closer to the end surface among the plurality of reflecting surfaces have higher height positions.

[0117] [10th viewpoint] On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), The optical element according to the eighth or ninth aspect, wherein the width (S31 to S33) of each of the plurality of step-like reflecting surfaces in the light guiding direction is equal to or less than half the pitch (P3) between adjacent step-like reflecting surfaces.

[0118] [Eleventh viewpoint] On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), An optical element according to any one of the eighth to tenth aspects, wherein the width of the split reflection portion in the light guide direction is equal to or smaller than the width of a region (2ba) of the exit portion onto which incident light (L2) from the incident surface is directly incident in the light guide direction. [Explanation of symbols]

[0119] 2...Light guide, 2a...Incidence surface, 2b...Emission part, 2ba...First area, 2bb...Second area 2c...Smooth surface, 2e...Terminal surface, 2f...divided reflection section, 3...prism section, 3a...output surface 4...Stepped reflecting surface, 41~43...(Stepped reflecting surface) flat surface 5, 51, 52...stepped portion (of stepped reflecting surface), 6...flat portion, 7...refractive index difference layer 71 to 73...flat surfaces (of the refractive index difference layer), 8, 81, 82...step portions (of the refractive index difference layer) 10: Stepped reflective surface; 11 to 13: Reflective surfaces; 14: Step portion; D1: Thickness direction D2...Light guiding direction, L1...Outside light, L2...Incoming light, S11~S13...Width of flat surface S21 to S23: Width of flat surface, S31 to S33: Width of reflecting surface, P2: Pitch of the refractive index difference layer, P3: Pitch of the stepped reflecting surface PP1, PP2...Pitch interval of prism part

Claims

1. An optical member that internally reflects and guides external light (L1), The light guide (2) includes an incident surface (2a) into which the external light is incident, an exit portion (2b) that emits a portion of the light incident from the incident surface to the outside, a smooth surface (2c) that faces the exit portion, and a terminal surface (2e) that is located on the opposite side to the incident surface and connects the exit portion and the smooth surface, and is made of a light-transmitting material; The emission portion has a first region (2ba) adjacent to the incident surface and a second region (2bb) adjacent to the first region, the first region has a plurality of stepped reflective surfaces (4) each having a plurality of flat surfaces (41-43) facing the smooth surface and located at different heights with step portions (5, 51, 52) in between, and a plurality of protruding prism portions (3), the stepped reflective surfaces and the prism portions being alternately and repeatedly arranged; The second region has a plurality of the prism portions and a plurality of flat portions (6) which are one flat surface, and the prism portions and the flat portions are arranged alternately and repeatedly, The flat surface, the flat portion, and the smooth surface reflect a part of the incident light (L2) that has entered the inside of the light guide from the incident surface by total reflection, The prism portion is an optical member having an exit surface (3a) that emits a part of the incident light to the outside.

2. A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the smooth surface toward the flat portion in the thickness direction is defined as down, and the positions of the plurality of flat surfaces in the thickness direction are defined as height positions, The optical member according to claim 1 , wherein the stepped reflecting surface has a lower height position than the flat surfaces closer to the end surface.

3. On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), 3. The optical element according to claim 1, wherein the first region has a width (S11 to S13) of each of the flat surfaces in the light guide direction that is equal to or less than half the pitch interval (PP1) between adjacent prism portions.

4. An optical member that internally reflects and guides external light (L1), a light guide (2) made of a light-transmitting material, the light guide (2) having an incident surface (2a) on which the external light is incident, an exit portion (2b) having a plurality of protruding prism portions (3) and a plurality of flat portions (6) that are flat surfaces and which emits a portion of the light incident from the entrance portion to the outside, a smooth surface (2c) facing the exit portion, and a terminal surface (2e) located on the opposite side of the incident surface and connecting the exit portion and the smooth surface; a plurality of refractive index difference layers (7) that are disposed in the vicinity of the emission portion inside the light guide, in a region where at least the incident light (L2) entering from the incident surface is directly incident, that are disposed at different heights via step portions (8, 81, 82), that have a plurality of flat surfaces (71-73) opposed to a plane formed by the smooth surface, and that have a refractive index lower than that of the light guide; the flat surface, the flat portion, and the smooth surface reflect a portion of the incident light by total reflection; The prism portion has an exit surface (3 a) that emits a part of the incident light to the outside, The plurality of refractive index difference layers are arranged at a distance from each other so as not to block light that is incident on the exit surface out of the incident light.

5. A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the smooth surface toward the flat portion in the thickness direction is defined as down, and the positions of the plurality of flat surfaces in the thickness direction are defined as height positions, The optical member according to claim 4 , wherein the refractive index difference layer has a lower height position for each of the flat surfaces that are closer to the terminal surface.

6. On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), 5. The optical member according to claim 4, wherein the width (S21 to S23) of each of the flat surfaces in the light guide direction of the refractive index difference layer is equal to or less than half the pitch interval (P2) between adjacent refractive index difference layers.

7. The optical member according to claim 4 , wherein the refractive index difference layer is an air layer.

8. An optical member that internally reflects and guides external light (L1), The light guide (2) is made of a light-transmitting material and includes an incident surface (2a) on which the external light is incident, an emission section (2b) having a plurality of protruding prism sections (3) and a plurality of flat sections (6) that are flat surfaces and emits a portion of the light incident from the incident surface to the outside, a dividing reflection section (2f) and a smooth surface (2c) that face the emission section, and a terminal surface (2e) that is located on the opposite side to the incident surface and connects the emission section and the smooth surface, The split reflection section is adjacent to the smooth surface, is located closer to the incident surface than the smooth surface, and is formed by repeatedly arranging a plurality of stepped reflection surfaces (10) in which a plurality of reflection surfaces (11 to 13) facing the surface formed by the plurality of flat portions are located at different heights with a step portion (14) between them, The reflecting surface, the flat portion, and the smooth surface reflect, by total reflection, a portion of the incident light (L2) that has entered the inside of the light guide from the incident surface, The prism portion is an optical member having an exit surface (3a) that emits a part of the incident light to the outside.

9. A direction connecting the flat portion and the smooth surface along a normal direction to the flat portion is defined as a thickness direction (D1), a direction from the flat portion toward the smooth surface in the thickness direction is defined as an up direction, and positions of the plurality of reflecting surfaces in the thickness direction are defined as height positions, The optical member according to claim 8 , wherein the step-like reflecting surface has a higher height position as the reflecting surface is closer to the end surface among the plurality of reflecting surfaces.

10. On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), 9. The optical element according to claim 8, wherein the width (S31 to S33) of each of the plurality of reflective surfaces in the light guiding direction is equal to or less than half the pitch (P3) between adjacent reflective surfaces.

11. On the plane formed by the flat portion, a direction from the incident surface toward the terminal surface along the arrangement direction of the flat portion and the prism portion is defined as a light guide direction (D2), An optical element according to any one of claims 8 to 10, wherein the width of the split reflection portion in the light guide direction is less than or equal to the width of a region (2ba) of the exit portion into which incident light (L2) from the incident surface is directly incident in the light guide direction.

Images